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Zheng M, Erhardt S, Cao Y, Wang J. Emerging Signaling Regulation of Sinoatrial Node Dysfunction. Curr Cardiol Rep 2023; 25:621-630. [PMID: 37227579 DOI: 10.1007/s11886-023-01885-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/14/2023] [Indexed: 05/26/2023]
Abstract
PURPOSE OF REVIEW The sinoatrial node (SAN), the natural pacemaker of the heart, is responsible for generating electrical impulses and initiating each heartbeat. Sinoatrial node dysfunction (SND) causes various arrhythmias such as sinus arrest, SAN block, and tachycardia/bradycardia syndrome. Unraveling the underlying mechanisms of SND is of paramount importance in the pursuit of developing effective therapeutic strategies for patients with SND. This review provides a concise summary of the most recent progress in the signaling regulation of SND. RECENT FINDINGS Recent studies indicate that SND can be caused by abnormal intercellular and intracellular signaling, various forms of heart failure (HF), and diabetes. These discoveries provide novel insights into the underlying mechanisms SND, advancing our understanding of its pathogenesis. SND can cause severe cardiac arrhythmias associated with syncope and an increased risk of sudden death. In addition to ion channels, the SAN is susceptible to the influence of various signalings including Hippo, AMP-activated protein kinase (AMPK), mechanical force, and natriuretic peptide receptors. New cellular and molecular mechanisms related to SND are also deciphered in systemic diseases such as HF and diabetes. Progress in these studies contributes to the development of potential therapeutics for SND.
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Affiliation(s)
- Mingjie Zheng
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Shannon Erhardt
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, The University of Texas, Houston, TX, 77030, USA
| | - Yuhan Cao
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Jun Wang
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, The University of Texas, Houston, TX, 77030, USA.
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Hatthakone T, Oundavong S, Soejima Y, Sawabe M. Development of a new histological identification method of human sinoatrial node suitable for immunohistochemical study. Anat Sci Int 2023; 98:293-305. [PMID: 36422826 DOI: 10.1007/s12565-022-00697-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 11/07/2022] [Indexed: 11/27/2022]
Abstract
Histological identification of the human sinoatrial node (SAN) remains a challenge. Conventional identification methods, such as Lev's method, have certain limitations. The aim of our study was to develop a new histological identification method that could properly identify the sinoatrial node, applicable to the immunohistochemical study of intra-nodal structures. Thirty-nine human autopsied hearts were included in this study. The cases included 23 men and 16 women ranging in age from 20 to 99 years. The sinoatrial area from eight control samples was cut in the vertical section using the conventional Lev's method. In our new method, called the "En face one-block method," the sinoatrial node was cut in "En face" at the junction of the right border of the right appendage and superior vena cava, placed in one long cassette, and serially cut using a microtome. Immunostaining was performed using primary antibodies against CD31, podoplanin (D2-40), S-100, and other proteins. The average area of the SAN on the slide glass in our new method was 32.2 mm2, which was significantly larger than that (3.59 mm2) of the control samples by Lev's method. The SAN area was positively correlated with age (r = 0.357; p = 0.026), especially in women (r = 0.626; p = 0.0095). The SAN group had significantly lower percentage of CD31-positive blood capillaries, higher percentage of podoplanin-positive lymphatic channels, and S-100-positive peripheral nerves. We successfully developed a novel cutting method applicable to immunohistochemical studies, with which we could provide a bird's-eye view of the sinoatrial nodes.
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Affiliation(s)
- Thavisouk Hatthakone
- Department of Molecular Pathology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo, 113-8510, Japan
| | - Sunti Oundavong
- Department of Molecular Pathology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo, 113-8510, Japan
| | - Yurie Soejima
- Department of Molecular Pathology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo, 113-8510, Japan
| | - Motoji Sawabe
- Department of Molecular Pathology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo, 113-8510, Japan.
- Department of Molecular Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo, 113-8519, Japan.
- Department of Diagnostic Pathology, Hitachi General Hospital, 2-1-1 Jonancho, Hitachi, Ibaraki, 317-0077, Japan.
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Chang X, Yao S, Wu Q, Wang Y, Liu J, Liu R. Tongyang Huoxue Decoction (TYHX) Ameliorating Hypoxia/Reoxygenation-Induced Disequilibrium of Calcium Homeostasis and Redox Imbalance via Regulating Mitochondrial Quality Control in Sinoatrial Node Cells. Oxid Med Cell Longev 2021; 2021:3154501. [PMID: 34422207 PMCID: PMC8373484 DOI: 10.1155/2021/3154501] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 07/13/2021] [Accepted: 07/23/2021] [Indexed: 12/14/2022]
Abstract
Sick sinus syndrome (SSS) is a disease with bradycardia or arrhythmia. The pathological mechanism of SSS is mainly due to the abnormal conduction function of the sinoatrial node (SAN) caused by interstitial lesions or fibrosis of the SAN or surrounding tissues, SAN pacing dysfunction, and SAN impulse conduction accompanied by SAN fibrosis. Tongyang Huoxue Decoction (TYHX) is widely used in SSS treatment and amelioration of SAN fibrosis. It has a variety of active ingredients to regulate the redox balance and mitochondrial quality control. This study mainly discusses the mechanism of TYHX in ameliorating calcium homeostasis disorder and redox imbalance of sinoatrial node cells (SANCs) and clarifies the protective mechanism of TYHX on the activity of SANCs. The activity of SANCs was determined by CCK-8 and the TUNEL method. The levels of apoptosis, ROS, and calcium release were analyzed by flow cytometry and immunofluorescence. The mRNA and protein levels of calcium channel regulatory molecules and mitochondrial quality control-related molecules were detected by real-time quantitative PCR and Western Blot. The level of calcium release was detected by laser confocal. It was found that after H/R treatment, the viability of SANCs decreased significantly, the levels of apoptosis and ROS increased, and the cells showed calcium overload, redox imbalance, and mitochondrial dysfunction. After treatment with TYHX, the cell survival level was improved, calcium overload and oxidative stress were inhibited, and mitochondrial energy metabolism and mitochondrial function were restored. However, after the SANCs were treated with siRNA (si-β-tubulin), the regulation of TYHX on calcium homeostasis and redox balance was counteracted. These results suggest that β-tubulin interacts with the regulation of mitochondrial function and calcium release. TYHX may regulate mitochondrial quality control, maintain calcium homeostasis and redox balance, and protect SANCs through β-tubulin. The regulation mechanism of TYHX on mitochondrial quality control may also become a new target for SSS treatment.
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Affiliation(s)
- Xing Chang
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Shunyu Yao
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Qiaomin Wu
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Yanli Wang
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Jinfeng Liu
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Ruxiu Liu
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
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Bois MC, Wu CW, Martinez CM, Castonguay MC, Jenkins SM, Maleszewski JJ. Age-related histologic features of the sinoatrial node from normal human hearts during the first 10 decades of life: a study of 200 cases. Cardiovasc Pathol 2021; 52:107327. [PMID: 33636251 DOI: 10.1016/j.carpath.2021.107327] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/12/2021] [Accepted: 02/12/2021] [Indexed: 01/06/2023] Open
Abstract
Knowledge of the histologic constituency of the sinoatrial (SA) node is based on small studies with unevenly distributed ages and subjective assessments of nodal composition, leading to difficulties in interpreting what constitutes true pathology of the SA node. SA nodes from two-hundred normal hearts (10 male and 10 female from each of the first 10 decades of life) were digitally analyzed to assess their histologic composition. Both nodal area and nodal fat content (≥5%) showed a quadratic relationship with age, peaking in the fifth to eighth decades of life. Increased fat content was also more prevalent with increased BMI (≥25 kg/m2). No differences between sexes were observed. Mean nodal collagen ranged from 7.1% to 50.3%, without a statistically significant differences by age or body mass index (BMI). The data suggests that the designation of pathologic fibrosis should be reserved for SA nodes with >50% collagen content. These findings expand and refine our understanding of the anatomy of the SA node.
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Affiliation(s)
- Melanie C Bois
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Cecilia W Wu
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | | | | | - Sarah M Jenkins
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN, USA
| | - Joseph J Maleszewski
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA.
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Petkova M, Atkinson AJ, Yanni J, Stuart L, Aminu AJ, Ivanova AD, Pustovit KB, Geragthy C, Feather A, Li N, Zhang Y, Oceandy D, Perde F, Molenaar P, D’Souza A, Fedorov VV, Dobrzynski H. Identification of Key Small Non-Coding MicroRNAs Controlling Pacemaker Mechanisms in the Human Sinus Node. J Am Heart Assoc 2020; 9:e016590. [PMID: 33059532 PMCID: PMC7763385 DOI: 10.1161/jaha.120.016590] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 08/27/2020] [Indexed: 01/01/2023]
Abstract
Background The sinus node (SN) is the primary pacemaker of the heart. SN myocytes possess distinctive action potential morphology with spontaneous diastolic depolarization because of a unique expression of ion channels and Ca2+-handling proteins. MicroRNAs (miRs) inhibit gene expression. The role of miRs in controlling the expression of genes responsible for human SN pacemaking and conduction has not been explored. The aim of this study was to determine miR expression profile of the human SN as compared with that of non-pacemaker atrial muscle. Methods and Results SN and atrial muscle biopsies were obtained from donor or post-mortem hearts (n=10), histology/immunolabeling were used to characterize the tissues, TaqMan Human MicroRNA Arrays were used to measure 754 miRs, Ingenuity Pathway Analysis was used to identify miRs controlling SN pacemaker gene expression. Eighteen miRs were significantly more and 48 significantly less abundant in the SN than atrial muscle. The most interesting miR was miR-486-3p predicted to inhibit expression of pacemaking channels: HCN1 (hyperpolarization-activated cyclic nucleotide-gated 1), HCN4, voltage-gated calcium channel (Cav)1.3, and Cav3.1. A luciferase reporter gene assay confirmed that miR-486-3p can control HCN4 expression via its 3' untranslated region. In ex vivo SN preparations, transfection with miR-486-3p reduced the beating rate by ≈35±5% (P<0.05) and HCN4 expression (P<0.05). Conclusions The human SN possesses a unique pattern of expression of miRs predicted to target functionally important genes. miR-486-3p has an important role in SN pacemaker activity by targeting HCN4, making it a potential target for therapeutic treatment of SN disease such as sinus tachycardia.
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Affiliation(s)
- Maria Petkova
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Andrew J. Atkinson
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Joseph Yanni
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Luke Stuart
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Abimbola J. Aminu
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Alexandra D. Ivanova
- Department of Human and Animal PhysiologyLomonosov Moscow State UniversityMoscowRussia
| | - Ksenia B. Pustovit
- Department of Human and Animal PhysiologyLomonosov Moscow State UniversityMoscowRussia
| | - Connor Geragthy
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Amy Feather
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Ning Li
- Physiology and Cell Biology DepartmentThe Bob and Corrine Frick Center for Heart Failure and ArrhythmiaThe Ohio State University Wexner Medical CenterColumbusOH
| | - Yu Zhang
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Delvac Oceandy
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Filip Perde
- National Institute of Legal MedicineBucharestRomania
| | - Peter Molenaar
- School of Biomedical SciencesQueensland University of TechnologyBrisbaneAustralia
- Cardiovascular Molecular & Therapeutics Translational Research GroupThe Prince Charles HospitalBrisbaneAustralia
| | - Alicia D’Souza
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
| | - Vadim V. Fedorov
- Physiology and Cell Biology DepartmentThe Bob and Corrine Frick Center for Heart Failure and ArrhythmiaThe Ohio State University Wexner Medical CenterColumbusOH
| | - Halina Dobrzynski
- Division of Cardiovascular SciencesUniversity of ManchesterUnited Kingdom
- Department of AnatomyJagiellonian University Medical CollegeKrakowPoland
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Abstract
A biological pacemaker is one or more types of cellular components that, when implanted into certain regions of the heart, produce electrical stimuli that mimic that of the body's natural pacemaker cells. Somatic gene transfer, cell fusion, or cell transplantation provide a way to realize it as somatic reprogramming strategies, which involve transfer of genes encoding transcription factors to transform working myocardium into a surrogate sinoatrial node, are furthest along in the possibilities. The idea, no doubt, is bright and appealing. The objective herein intends to dig into the subject trying to find out how realizable it really is.
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Mao Z, Wang Y, Peng H, He F, Zhu L, Huang H, Huang X, Lu X, Tan X. A newly identified missense mutation in CLCA2 is associated with autosomal dominant cardiac conduction block. Gene 2019; 714:143990. [PMID: 31326550 DOI: 10.1016/j.gene.2019.143990] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 07/15/2019] [Accepted: 07/17/2019] [Indexed: 01/12/2023]
Abstract
BACKGROUND Progressive cardiac conduction defect (PCCD), also known as Lenegre-Lev disease, is one of the most common heart conduction abnormalities. Previous studies have screened for known mutation sites that cause heart block in a 68-person family with a history of PCCD, revealed no mutations. OBJECTIVE To screen pathogenic genes of the PCCD family and to study the function of the gene mutations related to heart block diseases. METHODS Whole exome sequencing (WES) was performed on two PCCD patients and one non-PCCD family member to find the related pathogenic gene. After family co-segregation and preliminary functional analysis, we identified the mutant gene CLCA2. To study the function of this gene, we constructed mutant-gene mice using CRISPR-Cas9 technology, and electrocardiogram monitoring was performed after genotype verification. RESULTS The CLCA2 c.G1725T mutation was identified and co-segregated with the phenotype. The analysis showed that the CLCA2 c.G1725T mutation is harmful and mainly affects protein glycosylation. Immunofluorescence staining revealed that CLCA2 was highly expressed in the sinoatrial node (SAN) tissues. Electrocardiogram monitoring of the mice revealed that CLCA2 point mutations induced mild conduction block and ectopic pacemakers. CONCLUSION Our findings indicate that a novel heterozygous missense mutation c.G1725T of the CLCA2 gene may be associated with heart block disease and the mutation in this gene may lead to sinus node lesions and conduction blocking.
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Affiliation(s)
- Zhuo Mao
- Reproductive and Genetic Center of Central Hospital of Xiangtan, 120 Heping Road, Yuhu District, Xiangtan City 411100, Hunan Province, China
| | - Yi Wang
- Reproductive and Genetic Center of Central Hospital of Xiangtan, 120 Heping Road, Yuhu District, Xiangtan City 411100, Hunan Province, China
| | - Hao Peng
- Reproductive and Genetic Center of Central Hospital of Xiangtan, 120 Heping Road, Yuhu District, Xiangtan City 411100, Hunan Province, China
| | - Fang He
- Reproductive and Genetic Center of Central Hospital of Xiangtan, 120 Heping Road, Yuhu District, Xiangtan City 411100, Hunan Province, China
| | - Li Zhu
- Reproductive and Genetic Center of Central Hospital of Xiangtan, 120 Heping Road, Yuhu District, Xiangtan City 411100, Hunan Province, China
| | - He Huang
- Cardiovascular Medicine of Central Hospital of Xiangtan, 120 Heping Road, Yuhu District, Xiangtan City 411100, Hunan Province, China
| | - Xianghong Huang
- Reproductive and Genetic Center of Central Hospital of Xiangtan, 120 Heping Road, Yuhu District, Xiangtan City 411100, Hunan Province, China
| | - Xiaowei Lu
- Reproductive and Genetic Center of Central Hospital of Xiangtan, 120 Heping Road, Yuhu District, Xiangtan City 411100, Hunan Province, China
| | - Xiaojun Tan
- Reproductive and Genetic Center of Central Hospital of Xiangtan, 120 Heping Road, Yuhu District, Xiangtan City 411100, Hunan Province, China.
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Tohno Y, Tohno S, Quiggins R, Minami T, Mahakkanukrauh P. Scarce Occurrence of Calcification in Human Sinoatrial Nodal Arteries in Old Age. Biol Trace Elem Res 2018; 184:24-32. [PMID: 28986768 DOI: 10.1007/s12011-017-1173-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 09/27/2017] [Indexed: 10/18/2022]
Abstract
To elucidate age-related changes of the sinoatrial (sinuatrial) nodal (SAN) artery, the authors investigated age-related changes of elements in the SAN artery by direct chemical analysis. In addition, the effects of different arterial origins, arterial sizes, and genders on element accumulation were investigated in the SAN artery. Fifty-nine formalin-fixed adult Thai hearts were dissected, and the following three types of the SAN artery were found: The first type was a single SAN artery arising from the right coronary artery (RCA). The second type was a single SAN artery arising from the proximal segment of the left circumflex artery (LCX). The third type was dual SAN artery arising from both the RCA and the LCX. For element analysis, both 41 single SAN arteries arising from the RCA and the LCX and 18 larger branches of dual SAN artery were used. After the arteries were incinerated with nitric acid and perchloric acid, element contents were determined by inductively coupled plasma-atomic emission spectrometry. It was found that seven element contents such as Ca, P, S, Mg, Zn, Fe, and Na did not change significantly in the SAN arteries with aging. Regarding the relationships among seven elements in the SAN arteries, extremely significant direct correlations were found among P, S, Mg, and Fe contents with one exception. However, no significant correlations were found between Ca and either P or Mg contents in the SAN arteries. To examine an effect of the different arterial origins on element accumulation, the SAN arteries were separated into the RCA and the LCX groups by the arterial origin and age-related changes of element contents were compared between two groups. It was found that there were no significant differences between the RCA and the LCX groups in age-related changes of Ca and P contents. No gender differences were found in age-related changes of Ca and P contents in the SAN arteries. To elucidate whether calcification occurred in the SAN arteries in old age, both the mass ratios of Ca/P and Mg/Ca were estimated in the SAN arteries. The mass ratio of Ca/P increased progressively in the SAN arteries with Ca increase, being not constant. The mass ratio of Mg/Ca decreased gradually in the SAN arteries with Ca increase, but the average mass ratio of Mg/Ca was very high, being 49.4 ± 16.5%. These results indicated that calcification scarcely occurred in the SAN arteries in old age, independently of the arterial origin and gender.
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Affiliation(s)
- Yoshiyuki Tohno
- Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
| | - Setsuko Tohno
- Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Ranida Quiggins
- Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Takeshi Minami
- Laboratory of Environmental Biology, Department of Life Science, Faculty of Science and Technology, Kinki University, Higashi-Osaka, Osaka, 577-8502, Japan
| | - Pasuk Mahakkanukrauh
- Department of Anatomy, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand
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Yavari A, Bellahcene M, Bucchi A, Sirenko S, Pinter K, Herring N, Jung JJ, Tarasov KV, Sharpe EJ, Wolfien M, Czibik G, Steeples V, Ghaffari S, Nguyen C, Stockenhuber A, Clair JRS, Rimmbach C, Okamoto Y, Yang D, Wang M, Ziman BD, Moen JM, Riordon DR, Ramirez C, Paina M, Lee J, Zhang J, Ahmet I, Matt MG, Tarasova YS, Baban D, Sahgal N, Lockstone H, Puliyadi R, de Bono J, Siggs OM, Gomes J, Muskett H, Maguire ML, Beglov Y, Kelly M, Dos Santos PPN, Bright NJ, Woods A, Gehmlich K, Isackson H, Douglas G, Ferguson DJP, Schneider JE, Tinker A, Wolkenhauer O, Channon KM, Cornall RJ, Sternick EB, Paterson DJ, Redwood CS, Carling D, Proenza C, David R, Baruscotti M, DiFrancesco D, Lakatta EG, Watkins H, Ashrafian H. Mammalian γ2 AMPK regulates intrinsic heart rate. Nat Commun 2017; 8:1258. [PMID: 29097735 PMCID: PMC5668267 DOI: 10.1038/s41467-017-01342-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/08/2017] [Indexed: 11/22/2022] Open
Abstract
AMPK is a conserved serine/threonine kinase whose activity maintains cellular energy homeostasis. Eukaryotic AMPK exists as αβγ complexes, whose regulatory γ subunit confers energy sensor function by binding adenine nucleotides. Humans bearing activating mutations in the γ2 subunit exhibit a phenotype including unexplained slowing of heart rate (bradycardia). Here, we show that γ2 AMPK activation downregulates fundamental sinoatrial cell pacemaker mechanisms to lower heart rate, including sarcolemmal hyperpolarization-activated current (I f) and ryanodine receptor-derived diastolic local subsarcolemmal Ca2+ release. In contrast, loss of γ2 AMPK induces a reciprocal phenotype of increased heart rate, and prevents the adaptive intrinsic bradycardia of endurance training. Our results reveal that in mammals, for which heart rate is a key determinant of cardiac energy demand, AMPK functions in an organ-specific manner to maintain cardiac energy homeostasis and determines cardiac physiological adaptation to exercise by modulating intrinsic sinoatrial cell behavior.
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Affiliation(s)
- Arash Yavari
- Experimental Therapeutics, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK.
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK.
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK.
| | - Mohamed Bellahcene
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Annalisa Bucchi
- Department of Biosciences, Università degli Studi di Milano, Milan, 20133, Italy
- Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, Milan, 20133, Italy
| | - Syevda Sirenko
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Katalin Pinter
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Neil Herring
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Julia J Jung
- Department of Cardiac Surgery, Rostock University Medical Centre, 18057, Rostock, Germany
- Department Life, Light and Matter, Interdisciplinary Faculty, Rostock University, 18059, Rostock, Germany
| | - Kirill V Tarasov
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Emily J Sharpe
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Markus Wolfien
- Department of Systems Biology and Bioinformatics, University of Rostock, Rostock, 18051, Germany
| | - Gabor Czibik
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Violetta Steeples
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Sahar Ghaffari
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Chinh Nguyen
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Alexander Stockenhuber
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Joshua R St Clair
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Christian Rimmbach
- Department of Cardiac Surgery, Rostock University Medical Centre, 18057, Rostock, Germany
- Department Life, Light and Matter, Interdisciplinary Faculty, Rostock University, 18059, Rostock, Germany
| | - Yosuke Okamoto
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Mingyi Wang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Bruce D Ziman
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Jack M Moen
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Daniel R Riordon
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Christopher Ramirez
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Manuel Paina
- Department of Biosciences, Università degli Studi di Milano, Milan, 20133, Italy
- Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, Milan, 20133, Italy
| | - Joonho Lee
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Jing Zhang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Ismayil Ahmet
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Michael G Matt
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Yelena S Tarasova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Dilair Baban
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Natasha Sahgal
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Helen Lockstone
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Rathi Puliyadi
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Joseph de Bono
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Owen M Siggs
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
- MRC Human Immunology Unit, Weatherall Institute for Molecular Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - John Gomes
- Department of Medicine, BHF Laboratories, The Rayne Institute, University College London, London, WC1E 6JJ, UK
| | - Hannah Muskett
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Mahon L Maguire
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Youlia Beglov
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Matthew Kelly
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Pedro P N Dos Santos
- Instituto de Pós-Graduação, Faculdade de Ciências Médicas de Minas Gerais, Belo Horizonte, 30.130-110, Brazil
| | - Nicola J Bright
- Cellular Stress Group, MRC London Institute of Medical Sciences, Imperial College London, London, W12 0NN, UK
| | - Angela Woods
- Cellular Stress Group, MRC London Institute of Medical Sciences, Imperial College London, London, W12 0NN, UK
| | - Katja Gehmlich
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Henrik Isackson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
| | - Gillian Douglas
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - David J P Ferguson
- Nuffield Department of Clinical Laboratory Science, University of Oxford, Oxford, OX3 9DU, UK
| | - Jürgen E Schneider
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Andrew Tinker
- Department of Medicine, BHF Laboratories, The Rayne Institute, University College London, London, WC1E 6JJ, UK
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, UK
| | - Olaf Wolkenhauer
- Department of Systems Biology and Bioinformatics, University of Rostock, Rostock, 18051, Germany
- Stellenbosch Institute of Advanced Study (STIAS), Wallenberg Research Centre at Stellenbosch University, Stellenbosch, 7602, South Africa
| | - Keith M Channon
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Richard J Cornall
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
- MRC Human Immunology Unit, Weatherall Institute for Molecular Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Eduardo B Sternick
- Instituto de Pós-Graduação, Faculdade de Ciências Médicas de Minas Gerais, Belo Horizonte, 30.130-110, Brazil
| | - David J Paterson
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Charles S Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
| | - David Carling
- Cellular Stress Group, MRC London Institute of Medical Sciences, Imperial College London, London, W12 0NN, UK
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Robert David
- Department of Cardiac Surgery, Rostock University Medical Centre, 18057, Rostock, Germany
- Department Life, Light and Matter, Interdisciplinary Faculty, Rostock University, 18059, Rostock, Germany
| | - Mirko Baruscotti
- Department of Biosciences, Università degli Studi di Milano, Milan, 20133, Italy
- Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, Milan, 20133, Italy
| | - Dario DiFrancesco
- Department of Biosciences, Università degli Studi di Milano, Milan, 20133, Italy
- Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, Milan, 20133, Italy
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Houman Ashrafian
- Experimental Therapeutics, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK.
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK.
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK.
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10
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Vagos MR, Arevalo H, de Oliveira BL, Sundnes J, Maleckar MM. A computational framework for testing arrhythmia marker sensitivities to model parameters in functionally calibrated populations of atrial cells. Chaos 2017; 27:093941. [PMID: 28964122 DOI: 10.1063/1.4999476] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Models of cardiac cell electrophysiology are complex non-linear systems which can be used to gain insight into mechanisms of cardiac dynamics in both healthy and pathological conditions. However, the complexity of cardiac models can make mechanistic insight difficult. Moreover, these are typically fitted to averaged experimental data which do not incorporate the variability in observations. Recently, building populations of models to incorporate inter- and intra-subject variability in simulations has been combined with sensitivity analysis (SA) to uncover novel ionic mechanisms and potentially clarify arrhythmogenic behaviors. We used the Koivumäki human atrial cell model to create two populations, representing normal Sinus Rhythm (nSR) and chronic Atrial Fibrillation (cAF), by varying 22 key model parameters. In each population, 14 biomarkers related to the action potential and dynamic restitution were extracted. Populations were calibrated based on distributions of biomarkers to obtain reasonable physiological behavior, and subjected to SA to quantify correlations between model parameters and pro-arrhythmia markers. The two populations showed distinct behaviors under steady state and dynamic pacing. The nSR population revealed greater variability, and more unstable dynamic restitution, as compared to the cAF population, suggesting that simulated cAF remodeling rendered cells more stable to parameter variation and rate adaptation. SA revealed that the biomarkers depended mainly on five ionic currents, with noted differences in sensitivities to these between nSR and cAF. Also, parameters could be selected to produce a model variant with no alternans and unaltered action potential morphology, highlighting that unstable dynamical behavior may be driven by specific cell parameter settings. These results ultimately suggest that arrhythmia maintenance in cAF may not be due to instability in cell membrane excitability, but rather due to tissue-level effects which promote initiation and maintenance of reentrant arrhythmia.
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Affiliation(s)
- Márcia R Vagos
- Scientific Computing Department, Simula Research Laboratory, 1325 Lysaker, Norway
| | - Hermenegild Arevalo
- Scientific Computing Department, Simula Research Laboratory, 1325 Lysaker, Norway
| | | | - Joakim Sundnes
- Scientific Computing Department, Simula Research Laboratory, 1325 Lysaker, Norway
| | - Mary M Maleckar
- Scientific Computing Department, Simula Research Laboratory, 1325 Lysaker, Norway
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Liu YQ, Gao YB, Dong J, Yao BW, Zhao L, Peng RY. Pathological changes in the sinoatrial node tissues of rats caused by pulsed microwave exposure. Biomed Environ Sci 2015; 28:72-75. [PMID: 25566864 DOI: 10.3967/bes2015.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 07/02/2014] [Indexed: 06/04/2023]
Abstract
To observe microwave induced dynamic pathological changes in the sinus nodes, wistar rats were exposed to 0, 5, 10, 50 mW/cm2 microwave. In 10 and 50 mW/cm2 groups, disorganized sinoatrial node cells, cell swelling, cytoplasmic condensation, nuclear pyknosis, and anachromasis, swollen, and empty mitochondria, and blurred and focally dissolved myofibrils could be detected from 1 to 28 d, while reduced parenchymal cells, increased collagen fibers, and extracellular matrix remodeling of interstitial cells were observed from 6 to 12 months. In conclusion, 10 and 50 mW/cm2 microwave could cause structural damages in the sinoatrial node and extracellular matrix remodeling in rats.
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Affiliation(s)
- Yan Qing Liu
- Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing 100850, China; The Affiliated Hospital of Logistic College of Chinese People's Armed Police Forces, Tianjin 300162, China
| | - Ya Bing Gao
- Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Ji Dong
- Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Bin Wei Yao
- Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Li Zhao
- Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Rui Yun Peng
- Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing 100850, China
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12
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Li J, Inada S, Schneider JE, Zhang H, Dobrzynski H, Boyett MR. Three-dimensional computer model of the right atrium including the sinoatrial and atrioventricular nodes predicts classical nodal behaviours. PLoS One 2014; 9:e112547. [PMID: 25380074 PMCID: PMC4224508 DOI: 10.1371/journal.pone.0112547] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 10/07/2014] [Indexed: 11/18/2022] Open
Abstract
The aim of the study was to develop a three-dimensional (3D) anatomically-detailed model of the rabbit right atrium containing the sinoatrial and atrioventricular nodes to study the electrophysiology of the nodes. A model was generated based on 3D images of a rabbit heart (atria and part of ventricles), obtained using high-resolution magnetic resonance imaging. Segmentation was carried out semi-manually. A 3D right atrium array model (∼3.16 million elements), including eighteen objects, was constructed. For description of cellular electrophysiology, the Rogers-modified FitzHugh-Nagumo model was further modified to allow control of the major characteristics of the action potential with relatively low computational resource requirements. Model parameters were chosen to simulate the action potentials in the sinoatrial node, atrial muscle, inferior nodal extension and penetrating bundle. The block zone was simulated as passive tissue. The sinoatrial node, crista terminalis, main branch and roof bundle were considered as anisotropic. We have simulated normal and abnormal electrophysiology of the two nodes. In accordance with experimental findings: (i) during sinus rhythm, conduction occurs down the interatrial septum and into the atrioventricular node via the fast pathway (conduction down the crista terminalis and into the atrioventricular node via the slow pathway is slower); (ii) during atrial fibrillation, the sinoatrial node is protected from overdrive by its long refractory period; and (iii) during atrial fibrillation, the atrioventricular node reduces the frequency of action potentials reaching the ventricles. The model is able to simulate ventricular echo beats. In summary, a 3D anatomical model of the right atrium containing the cardiac conduction system is able to simulate a wide range of classical nodal behaviours.
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Affiliation(s)
- Jue Li
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility, Manchester, United Kingdom
| | - Shin Inada
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility, Manchester, United Kingdom
| | - Jurgen E. Schneider
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility, Manchester, United Kingdom
| | - Henggui Zhang
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility, Manchester, United Kingdom
| | - Halina Dobrzynski
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility, Manchester, United Kingdom
| | - Mark R. Boyett
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility, Manchester, United Kingdom
- * E-mail:
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13
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Wang J, Bai Y, Li N, Ye W, Zhang M, Greene SB, Tao Y, Chen Y, Wehrens XHT, Martin JF. Pitx2-microRNA pathway that delimits sinoatrial node development and inhibits predisposition to atrial fibrillation. Proc Natl Acad Sci U S A 2014; 111:9181-6. [PMID: 24927531 PMCID: PMC4078868 DOI: 10.1073/pnas.1405411111] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The molecular mechanisms underlying atrial fibrillation, the most common sustained cardiac arrhythmia, remain poorly understood. Genome-wide association studies uncovered a major atrial fibrillation susceptibility locus on human chromosome 4q25 in close proximity to the paired-like homeodomain transcription factor 2 (Pitx2) homeobox gene. Pitx2, a target of the left-sided Nodal signaling pathway that initiates early in development, represses the sinoatrial node program and pacemaker activity on the left side. To address the mechanisms underlying this repressive activity, we hypothesized that Pitx2 regulates microRNAs (miRs) to repress the sinoatrial node genetic program. MiRs are small noncoding RNAs that regulate gene expression posttranscriptionally. Using an integrated genomic approach, we discovered that Pitx2 positively regulates miR-17-92 and miR-106b-25. Intracardiac electrical stimulation revealed that both miR-17-92 and miR-106b-25 deficient mice exhibit pacing-induced atrial fibrillation. Furthermore electrocardiogram telemetry revealed that mice with miR-17-92 cardiac-specific inactivation develop prolonged PR intervals whereas mice with miR-17-92 cardiac-specific inactivation and miR-106b-25 heterozygosity develop sinoatrial node dysfunction. Both arrhythmias are risk factors for atrial fibrillation in humans. Importantly, miR-17-92 and miR-106b-25 directly repress genes, such as Shox2 and Tbx3, that are required for sinoatrial node development. Together, to our knowledge, these findings provide the first genetic evidence for an miR loss-of-function that increases atrial fibrillation susceptibility.
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Affiliation(s)
- Jun Wang
- Department of Molecular Physiology and Biophysics
| | - Yan Bai
- Department of Molecular Physiology and Biophysics,Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030; and
| | - Na Li
- Department of Molecular Physiology and Biophysics
| | - Wenduo Ye
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118
| | - Min Zhang
- Department of Molecular Physiology and Biophysics,Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030; and
| | | | - Ye Tao
- Department of Molecular Physiology and Biophysics
| | - Yiping Chen
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118
| | - Xander H T Wehrens
- Department of Molecular Physiology and Biophysics,Department of Medicine, Division of Cardiology, Baylor College of Medicine, Houston, TX 77030
| | - James F Martin
- Department of Molecular Physiology and Biophysics,Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030; andTexas Heart Institute, Houston, TX 77030;Program in Developmental Biology, and
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Tsuneki R, Doi S, Inoue J. Generation of slow phase-locked oscillation and variability of the interspike intervals in globally coupled neuronal oscillators. Math Biosci Eng 2014; 11:125-138. [PMID: 24245673 DOI: 10.3934/mbe.2014.11.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
To elucidate how a biological rhythm is regulated, the extended (three-dimensional) Bonhoeffer-van der Pol or FitzHugh-Nagumo equations are employed to investigate the dynamics of a population of neuronal oscillators globally coupled through a common buffer (mean field). Interesting phenomena, such as extraordinarily slow phase-locked oscillations (compared to the natural period of each neuronal oscillator) and the death of all oscillations, are observed. We demonstrate that the slow synchronization is due mainly to the existence of "fast" oscillators. Additionally, we examine the effect of noise on the synchronization and variability of the interspike intervals. Peculiar phenomena, such as noise-induced acceleration and deceleration, are observed. The results herein suggest that very small noise may significantly influence a biological rhythm.
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Affiliation(s)
- Ryotaro Tsuneki
- Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
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Ion DA. Doctoral and post-doctoral research – a priority of the Romanian postgraduate education system (Doc-Postdoc). Rom J Morphol Embryol 2014; 55:1531–1532. [PMID: 25751894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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16
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Ruisu K, Kask K, Meier R, Saare M, Raid R, Veraksitš A, Karis A, Tõnissoo T, Pooga M. Ablation of RIC8A function in mouse neurons leads to a severe neuromuscular phenotype and postnatal death. PLoS One 2013; 8:e74031. [PMID: 23977396 PMCID: PMC3745415 DOI: 10.1371/journal.pone.0074031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 07/30/2013] [Indexed: 12/29/2022] Open
Abstract
Resistance to inhibitors of cholinesterase 8 (RIC8) is a guanine nucleotide exchange factor required for the intracellular regulation of G protein signalling. RIC8 activates different Gα subunits via non-canonical pathway, thereby amplifying and prolonging the G protein mediated signal. In order to circumvent the embryonic lethality associated with the absence of RIC8A and to study its role in the nervous system, we constructed Ric8a conditional knockout mice using Cre/loxP technology. Introduction of a synapsin I promoter driven Cre transgenic mouse strain (SynCre) into the floxed Ric8a (Ric8a (F/F) ) background ablated RIC8A function in most differentiated neuron populations. Mutant SynCre (+/-) Ric8 (lacZ/F) mice were born at expected Mendelian ratio, but they died in early postnatal age (P4-P6). The mutants exhibited major developmental defects, like growth retardation and muscular weakness, impaired coordination and balance, muscular spasms and abnormal heart beat. Histological analysis revealed that the deficiency of RIC8A in neurons caused skeletal muscle atrophy and heart muscle hypoplasia, in addition, the sinoatrial node was misplaced and its size reduced. However, we did not observe gross morphological changes in brains of SynCre (+/-) Ric8a (lacZ/F) mutants. Our results demonstrate that in mice the activity of RIC8A in neurons is essential for survival and its deficiency causes a severe neuromuscular phenotype.
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Affiliation(s)
- Katrin Ruisu
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- * E-mail: (KR); (TT)
| | - Keiu Kask
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Riho Meier
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Merly Saare
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Raivo Raid
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Alar Veraksitš
- Institute of Biomedicine and Translational Medicine, Department of Physiology, University of Tartu, Tartu, Estonia
| | - Alar Karis
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Tambet Tõnissoo
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- * E-mail: (KR); (TT)
| | - Margus Pooga
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
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Li X, Zhang J, Cheng R, Jiang Y, Gao F. [A simulation study for the effect of acid concentration and temperture on sick sinus syndrome]. Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 2013; 30:697-703. [PMID: 24059039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The effective therapeutics for the sinoatrial node (SAN) pacemaker dysfunction induced by SCN5A gene mutation this is still being explored recently. In this study, a two-dimensional experimental model of rabbit SAN-atrial cell system which proposed by Zhang et al., was used as a prototype, the gene mutation was considered, and effects of both the acid concentration and temperature were also introduced. The effects of acid concentration and temperature on sick sinus syndrome (SSS) at the tissue level were investigated by simulation. The results showed that the SAN abnormal pacemaker could be caused by the reduction of I(Na), which is induced by the two mutations of T220I and delF1617. The results also showed that if we properly adjusted the acid concentration and temperature of the system, not only could we increase the relevant currents, but also could we increase I(Na) which reduced by gene mutations, so that the pacemaking behavior of SAN tissue could return to normal state from abnormalities. The above simulation results imply that the abnormal pacemaking of SAN system may closely relate to the gene mutation of ion channel mutations, and the acid concentration and temperature may play a modulatory role. Our study could be useful for clinical medical diagnosis and therapy of cardiac disease.
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Affiliation(s)
- Xiang Li
- College of Physics and Electronic Informnation, Anhui Normal University, Wuhu 241000, China
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18
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Comunoglu C, Comunoglu N, Eren B, Tanrlöver O, Türkmen N, Gündogmuş UN, Eren F. Age-related histopathological changes in the cardiac conducting system in the Turkish population: an evaluation of 202 autopsy cases. Folia Morphol (Warsz) 2012; 71:178-182. [PMID: 22936554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
BACKGROUND Histopathological features of the cardiac conducting system (CCS) in the Turkish population have not been investigated previously. MATERIAL AND METHODS We examined CCS of 202 autopsy heart specimens dissected between the years 2004 and 2005 in Bursa Forensic Medicine Institution. Of the 202 cases from all age groups, 154 were males and 48 were females. RESULTS In our cases, an increase in fibrous and adipose tissue concordant with age, indicating an age-related nature, were detected. Fibrous and fatty tissue infiltration appeared at the age of 35. Fatty infiltration started between the ages 20 and 34 years at the sinoatrial node (SAN). There was no relationship between obesity and fatty tissue infiltration in SAN and atrioventricular node (AVN). In 4 cases calcification and in 19 cases inflammation was observed. Amyloid accumulation was not present. In 7 cases myocardial infarction not involving CCS was seen. In 1 case fibroelastoma was detected. CONCLUSIONS In the Turkish population age-related fibrosis and fatty infiltration in CCS appeared at the age of 35 years and increased with age. Fatty infiltration in the SAN started at a younger age than that reported in the literature. In cases where the cause of death could not be determined, we could not detect lethal pathological features. However, we think that examination of the CCS will improve the quality of autopsy diagnosis.
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Affiliation(s)
- C Comunoglu
- Department of Pathology, Near East University Faculty of Medicine, Nicosia, North Cyprus.
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Sizarov A, Devalla HD, Anderson RH, Passier R, Christoffels VM, Moorman AFM. Molecular analysis of patterning of conduction tissues in the developing human heart. Circ Arrhythm Electrophysiol 2011; 4:532-42. [PMID: 21576278 DOI: 10.1161/circep.111.963421] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Recent studies in experimental animals have revealed some molecular mechanisms underlying the differentiation of the myocardium making up the conduction system. To date, lack of gene expression data for the developing human conduction system has precluded valid extrapolations from experimental studies to the human situation. METHODS AND RESULTS We performed immunohistochemical analyses of the expression of key transcription factors, such as ISL1, TBX3, TBX18, and NKX2-5, ion channel HCN4, and connexins in the human embryonic heart. We supplemented our molecular analyses with 3-dimensional reconstructions of myocardial TBX3 expression. TBX3 is expressed in the developing conduction system and in the right venous valve, atrioventricular ring bundles, and retro-aortic nodal region. TBX3-positive myocardium, with exception of the top of the ventricular septum, is devoid of fast-conducting connexin40 and connexin43 and hence identifies slowly conducting pathways. In the early embryonic heart, we found wide expression of the pacemaker channel HCN4 at the venous pole, including the atrial chambers. HCN4 expression becomes confined during later developmental stages to the components of the conduction system. Patterns of expression of transcription factors, known from experimental studies to regulate the development of the sinus node and atrioventricular conduction system, are similar in the human and mouse developing hearts. CONCLUSIONS Our findings point to the comparability of mechanisms governing the development of the cardiac conduction patterning in human and mouse, which provide a molecular basis for understanding the functioning of the human developing heart before formation of a discrete conduction system.
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Affiliation(s)
- Aleksander Sizarov
- Heart Failure Research Center, Academic Medical Center, Amsterdam, The Netherlands
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21
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Yi W, Yu YN, Zhang CY, Wen AZ, Long YG, Zhang H, Guan ZZ. [Pathologic changes of sinoatrial node P cells and cardiac myocytes in experimental fluorosis]. Zhonghua Bing Li Xue Za Zhi 2010; 39:264-265. [PMID: 20654127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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Abstract
Sinus node dysfunction after surgical repair of an atrial septal defect is a rather uncommon complication. We report a case of protracted post-operative sinus node dysfunction which was managed successfully by oral theophyllines and 'watchful' waiting. This strategy could avoid placement of a permanent pacemaker in this patient group of younger age.
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Affiliation(s)
- Kevin Onsea
- Department of Cardiology, Virga Jesse Ziekenhuis, Hasselt, Belgium
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Long DY, Ma CS, Jiang H, Dong JZ, Liu XP, Huang H, Tang YH, Wu G, Huang CX. Sinus node, phrenic nerve and electrical connections between superior vena cava and right atrium: lessons learned from a prospective study. Chin Med J (Engl) 2009; 122:675-680. [PMID: 19323933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
BACKGROUND When performing superior vena cava isolation, the major concerns are inadvertent ablation on sinus node and right phrenic nerve. However, little is known about the spatial relationship of electrical connections between superior vena cava and right atrium with the sinus node and phrenic nerve locations among individual patients. METHODS We studied 87 patients (male/female 60/27, mean age of (51 +/- 9) years) with atrial fibrillation. Before superior vena cava isolation, the sinus node site was defined by right atrium activation mapping during sinus rhythm and the right phrenic nerve site was localized via pacing manoeuvre. Superior vena cava was isolated by ablation at the electrical connection under the guidance of circular mapping catheter. The sites of sinus node, phrenic nerve and electrical connections were noted. Continuous variables were compared using Student's t test. A P value < 0.05 was considered statistically significant. RESULTS Right atrium activation mapping revealed that the sinus node located at the anterior lateral segment of superior vena cava-right atrium junction in all patients. In 82 patients with detectable diaphragmatic stimulations, the phrenic nerve sites were predominantly at the lateral segment (70/82) with anterior lateral and anterior segments for a few patients. A total of 165 electrical connections were located among all 87 patients, and this averaged 1.8 +/- 0.6 (1-3) per patient. The anterior septum (72 patients (43.6%)), the anterior wall (40 (24.2%)), and the posterior septum (35 (35.4%)) of superior vena cava-right atrium junction were the electrical connection regular sites. Superior vena cava was isolated in all patients. Two patients developed sinus bradycardia, with 3 mild superior vena cava stenosis and 2 phrenic nerve palsy. CONCLUSIONS The sinus node, phrenic nerve and electrical connection sites were distributed along the superior vena cava-right atrium junctions at expected locations for most patients. The electrical connections were separated from the sinus node and phrenic nerve sites. With the activation mapping of right atrium and pacing along superior vena cava-right atrium junctions, the sinus node and phrenic nerve were localized and superior vena cava isolated in most patients.
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Affiliation(s)
- De-Yong Long
- Department of Cardiology, Renmin Hospital, Wuhan University, Wuhan, Hubei 430060, China
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Lemaire SA, Ochoa LN, Conklin LD, Schmittling ZC, Undar A, Clubb FJ, Li Wang X, Coselli JS, Fraser CD. Nerve and Conduction Tissue Injury Caused by Contact with BioGlue. J Surg Res 2007; 143:286-93. [PMID: 17765925 DOI: 10.1016/j.jss.2006.10.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2006] [Revised: 10/04/2006] [Accepted: 10/09/2006] [Indexed: 10/22/2022]
Abstract
BACKGROUND BioGlue-a surgical adhesive composed of bovine albumin and glutaraldehyde-is commonly used in cardiovascular operations. The objectives of this study were to determine whether BioGlue injures nerves and cardiac conduction tissues, and whether a water-soluble gel barrier protects against such injury. MATERIALS AND METHODS In 18 pigs, diaphragmatic excursion during direct phrenic nerve stimulation was measured at baseline and at 3 and 30 min after nerve exposure to albumin (n = 3), glutaraldehyde (n = 3), BioGlue (n = 6), or water-soluble gel followed by BioGlue (n = 6). Additionally, BioGlue was applied to the cavoatrial junction overlying the sinoatrial node (SAN), either alone (n = 12) or after application of gel (n = 6). RESULTS Mean diaphragmatic excursions in the BioGlue and glutaraldehyde groups were lower at 3 min and 30 min than in the albumin group (P < 0.05). Mean excursions in the gel group were similar to those of the albumin group (P = 0.9). Five BioGlue pigs (83%) and one gel pig (17%) had diaphragmatic paralysis by 30 min (P < 0.05 and P = 0.3 versus albumin, respectively). Coagulation necrosis extended into the myocardium at the cavoatrial junction in all 12 BioGlue pigs but only two gel pigs (33%, P < 0.01). Two BioGlue pigs (17%), but no gel pigs, had focal SAN degeneration and persistent bradycardia (P < 0.01). CONCLUSIONS BioGlue causes acute nerve injury and myocardial necrosis that can lead to SAN damage. A water-soluble gel barrier is protective.
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Affiliation(s)
- Scott A Lemaire
- Cardiovascular Surgery Service, the Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas 77030, USA.
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Herrmann S, Stieber J, Stöckl G, Hofmann F, Ludwig A. HCN4 provides a 'depolarization reserve' and is not required for heart rate acceleration in mice. EMBO J 2007; 26:4423-32. [PMID: 17914461 PMCID: PMC2063478 DOI: 10.1038/sj.emboj.7601868] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Accepted: 09/05/2007] [Indexed: 01/01/2023] Open
Abstract
Cardiac pacemaking involves a variety of ion channels, but their relative importance is controversial and remains to be determined. Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, which underlie the I(f) current of sinoatrial cells, are thought to be key players in cardiac automaticity. In addition, the increase in heart rate following beta-adrenergic stimulation has been attributed to the cAMP-mediated enhancement of HCN channel activity. We have now studied mice in which the predominant sinoatrial HCN channel isoform HCN4 was deleted in a temporally controlled manner. Here, we show that deletion of HCN4 in adult mice eliminates most of sinoatrial I(f) and results in a cardiac arrhythmia characterized by recurrent sinus pauses. However, the mutants show no impairment in heart rate acceleration during sympathetic stimulation. Our results reveal that unexpectedly the channel does not play a role for the increase of the heart rate; however, HCN4 is necessary for maintaining a stable cardiac rhythm, especially during the transition from stimulated to basal cardiac states.
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Affiliation(s)
- Stefan Herrmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- These authors contributed equally to this work
| | - Juliane Stieber
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- These authors contributed equally to this work
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany. Tel.: +49 9131 85 26936; Fax: +49 9131 85 22774; E-mail:
| | - Georg Stöckl
- Institut für Pharmakologie und Toxikologie, Technische Universität München, München, Germany
| | - Franz Hofmann
- Institut für Pharmakologie und Toxikologie, Technische Universität München, München, Germany
| | - Andreas Ludwig
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany. Tel.: +49 9131 85 22220; Fax: +49 9131 85 22774; E-mail:
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Swenne CA, Schalij MJ. Pacemaking in the AV node. Heart Rhythm 2007; 4:1336-7. [PMID: 17905340 DOI: 10.1016/j.hrthm.2007.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Indexed: 10/23/2022]
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Roberts-Thomson KC, Sanders P, Kalman JM. Sinus Node Disease: An Idiopathic Right Atrial Myopathy. Trends Cardiovasc Med 2007; 17:211-4. [PMID: 17662917 DOI: 10.1016/j.tcm.2007.06.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 06/05/2007] [Accepted: 06/12/2007] [Indexed: 11/30/2022]
Abstract
Sinus node disease was previously thought to be a disease limited to the sinus node and its atrial connections. However, recent reports have demonstrated sinus node disease as a disease of the entire right atrial myocardium. These patients have widespread electrophysiological abnormalities of their atria, including prolonged refractory periods and slowed conduction. In addition to these electrical changes, there are significant structural changes, such as fibrosis and fatty infiltration, which can be detected endocardially as regions of fractionated signals, low-voltage electrograms, and electrically silent areas. In most cases, the etiology of these changes is unknown. These changes may contribute to the high prevalence of atrial fibrillation seen in patients with sinus node disease.
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Abstract
Despite the findings that impaired vagal control of the heart rate occurs in human hypertension, leading to greater cardiovascular risk, the mechanism of this impairment is as yet unknown. Observations in humans and experiments in the spontaneously hypertensive rat (SHR) suggested that such impairment may be related to an anomaly in central vagal neurones. We therefore set out to determine whether the numbers and distribution of cardiac-projecting vagal preganglionic neurones in the medulla of adult (12 week) hypertensive SHR are different from those in young (4 week) prehypertensive SHR and in age-matched Wistar-Kyoto (WKY) rats of two age groups. The number of vagal neurones, identified by labelling with the fluorescent tracer DiI applied to the heart, was essentially similar in the three areas of the medulla analysed (dorsal vagal nucleus, nucleus ambiguus and intermediate reticular zone) in young SHR and young or adult WKY rats. In contrast, fewer vagal neurones were labelled in adult SHR compared with young SHR or WKY rats. This difference was due to highly significant reductions in vagal neurones in the dorsal vagal nucleus and nucleus ambiguus on the right side of the medulla. These observations suggest that a loss of parasympathetic preganglionic neurones supplying the heart with axons in the right vagus nerve, or a remodelling of their cardiac projections, may explain the known impairment of the baroreceptor reflex gain controlling heart rate in hypertension.
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Affiliation(s)
- Eric K A Corbett
- Institute for Cardiovascular Research (CRISTAL), Worsley Building, Clarendon Way, University of Leeds, Leeds LS2 9JT, UK
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Abstract
AIMS Children with congenital complete atrioventricular block (CCAVB) often need pacemaker therapy. In these children, it may be preferable to use single-lead VDD pacing, but for VDD pacing a normal sinus node function is required. Our aim was to study sinus node function in children with CCAVB. METHODS AND RESULTS We longitudinally evaluated sinus rate in 36 children with CCAVB and normal anatomy of the heart. The rate of sinus rhythm on a 12-lead ECG, in Holter recordings, and exercise tests were evaluated at regular intervals. Age at the first visit of the children was 2.5+/-3.3 years (mean+/-SD). Follow-up was 10.6+/-7.3 years. The rate of sinus rhythm on a 12-lead ECG was at every age within the normal values for age (e.g. 0-1 year: 153+/-24 bpm, and 17-18 years: 76+/-4 bpm). Lowest and highest sinus rates in the Holter recordings were normal. During exercise, mean sinus rate in the total group of children increased from 92+/-8 at rest to 171+/-9 bpm at maximal exercise. CONCLUSION We conclude that sinus node function is normal in children with CCAVB. Because of the normal increase in sinus rate during exercise, a single-lead VDD pacemaker can be safely implanted in these children.
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Affiliation(s)
- Gertie C M Beaufort-Krol
- Beatrix Children's Hospital, Division of Pediatric Cardiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9700 RB, Groningen, The Netherlands
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Ogawa M, Zhou S, Tan AY, Song J, Gholmieh G, Fishbein MC, Luo H, Siegel RJ, Karagueuzian HS, Chen LS, Lin SF, Chen PS. Left Stellate Ganglion and Vagal Nerve Activity and Cardiac Arrhythmias in Ambulatory Dogs With Pacing-Induced Congestive Heart Failure. J Am Coll Cardiol 2007; 50:335-43. [PMID: 17659201 DOI: 10.1016/j.jacc.2007.03.045] [Citation(s) in RCA: 173] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 02/20/2007] [Accepted: 03/06/2007] [Indexed: 11/27/2022]
Abstract
OBJECTIVES The purpose of this study was to determine the patterns of autonomic nerve activity in congestive heart failure (CHF). BACKGROUND The relationship between autonomic nerve activity and cardiac arrhythmias in CHF is unclear. METHODS We implanted radiotransmitters in 6 dogs for continuous (24/7) simultaneous monitoring of left stellate ganglion nerve activity (SGNA), vagal nerve activity (VNA), and electrocardiography before and after pacing-induced CHF. RESULTS Congestive heart failure increased both SGNA and VNA. The SGNA but not VNA manifested a circadian variation pattern. There was extensive sinus node fibrosis. We analyzed 2,263 episodes of prolonged (>3 s) sinus pauses (PSP) and 1,420 long (>10 s) episodes of paroxysmal atrial tachycardia (PAT). Most (95.3%) PSP episodes occurred at night, and 56% were preceded by a short burst of SGNA that induced transient sinus tachycardia. Long PAT episodes were typically (83%) induced by simultaneous SGNA and VNA discharge, followed by VNA withdrawal. Premature ventricular contractions and ventricular tachycardia were preceded by elevated SGNA. CONCLUSIONS The reduction of sympathovagal balance at night in ambulatory dogs was due to reduced sympathetic discharge rather than a net increase of vagal discharge. The tachybrady syndrome in CHF might be triggered by an intermittent short burst of SGNA that resulted in tachycardia and sinus node suppression. Simultaneous sympathovagal discharge is a cause of long PAT episodes. These data indicate that there is an association between the specific patterns of autonomic nerve discharges and cardiac arrhythmia during CHF.
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Affiliation(s)
- Masahiro Ogawa
- Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
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Abstract
BACKGROUND The main physiologic function of the AV junction is control of timing between atrial and ventricular excitation. However, under pathologic conditions, the AV junction may become the pacemaker of the heart. Unlike the well-characterized sinoatrial node (SAN), autonomic control of the AV junctional pacemaker has not been studied. OBJECTIVE The purpose of this study was to characterize the autonomic control and innervation of the AV junctional pacemaker. METHODS The response of rabbit AV junctional pacemaker to autonomic stimulation was investigated using optical mapping, autonomic modulation via subthreshold stimulation (n = 12), and quantitative immunohistochemistry (n = 5), and the density of parasympathetic and sympathetic innervation in optically mapped preparations was quantified. RESULTS Subthreshold stimulation applied adjacent to the conduction system in the triangle of Koch autonomically modulates the junctional rate, and parasympathetic and sympathetic components can be separated with atropine and the beta-blocker nadolol. Subthreshold stimulation increased the rate maximally to 2.1 +/- 0.4 times when applied with atropine. Unlike the SAN pacemaker, which shifts significantly in response to autonomic stimulation, the AV junctional pacemaker remains stationary (most often in the inferior nodal extension), moving in only 5% of subthreshold stimulation trials. Staining with tyrosine hydroxylase and choline acetyltransferase revealed heterogeneous innervation within the AV junction. CONCLUSION AV junctional rhythm can be autonomically modulated with subthreshold stimulation to produce junctional rates of 145 +/- 16 bpm (cycle length 412 +/- 29 ms), similar to sinus rates in rabbit. Unlike the SAN, the anatomic location of the AV junctional pacemaker is stable during autonomic modulation.
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Affiliation(s)
- William J Hucker
- Department of Biomedical Engineering, Washington University, One Brookings Drive, St. Louis, MO 63130, USA
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Kimura K, Yoon SH, Fukuda K, Kimura T, Takahashi K, Suzuki N, Imai A, Noma S. Cardiac "Bradykinesia" in advanced Parkinson's disease. Mov Disord 2007; 22:750-2. [PMID: 17299776 DOI: 10.1002/mds.21388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Abstract
BACKGROUND Interatrial conduction occurs via discrete pathways along the coronary sinus musculature, fossa ovalis region, and Bachman's bundle. We assessed the feasibility of altering interatrial conduction by selectively ablating two of these conduction pathways using a novel mesh electrode ablation catheter. METHODS Circular radiofrequency energy catheter ablation lesions were created in the proximal coronary sinus in four dogs and in both the fossa ovalis and the proximal coronary sinus regions in seven pigs. Interatrial conduction was assessed by analyzing intracardiac electrogram and noncontact isopotential mapping data. Inducibility of atrial fibrillation was assessed before and after ablation (in six pigs). RESULTS Ablation lesions in the proximal coronary sinus eliminated interatrial conduction along the coronary sinus musculature in four dogs and five of seven pigs. Ablation lesions in the fossa ovalis region eliminated interatrial conduction via midseptal pathways in six of seven pigs. Atrial fibrillation, inducible in five of seven pigs at baseline, was rendered noninducible in all five. There was no adverse effect on AV nodal conduction. CONCLUSIONS (1) Using a novel mesh electrode ablation catheter, we were able to ablate interatrial conduction pathways along the proximal coronary sinus and fossa ovalis regions. (2) This altered interatrial conduction and altered atrial fibrillation inducibility and maintenance. (3) Catheter ablation of interatrial conduction pathways may be useful in the therapy of atrial fibrillation.
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Affiliation(s)
- Peter Ott
- Sarver Heart Center, University of Arizona, Tucson, Arizona 85724, USA.
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Du Y, Huang X, Wang T, Han K, Zhang J, Xi Y, Wu G, Ma A. Downregulation of neuronal sodium channel subunits Nav1.1 and Nav1.6 in the sinoatrial node from volume-overloaded heart failure rat. Pflugers Arch 2007; 454:451-9. [PMID: 17273863 DOI: 10.1007/s00424-007-0216-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 01/14/2007] [Indexed: 10/23/2022]
Abstract
Sodium current I(Na) plays an important role in the pacemaker activity of the sinoatrial node (SAN). However, expression profiles of corresponding sodium channel subunits in normal SAN remain unclear. And little is known about expression alteration of sodium channel in SAN under heart failure (HF) condition. We assessed SAN function and expression of Nav1.1, Nav1.2, Nav1.3, Nav1.5, Nav1.6, and Nav1.7 in sham-operated rats and rats subjected to abdominal arteriovenous shunt (volume overload)-induced HF. Immunohistochemistry, Western blot, and quantitative real-time reverse transcriptase PCR analysis were used to quantify sodium channel subunit protein and mRNA expression in the SAN. Intrinsic heart rate declined and sinus node recovery time was prolonged in HF rats, indicating suppressed SAN pacemaker function. In rat SAN, Nav1.1 and Nav1.6 were the primary subunits, Nav1.5 and Nav1.7 were weakly expressed, and Nav1.2 and Nav1.3 were not found to be present. HF significantly decreased SAN sodium channel expression at both the protein and mRNA levels (Nav1.1 by 61 and 71%, Nav1.6 by 49 and 46%, respectively). In conclusion, Nav1.1 and Nav1.6 are the dominant subunits in rat SAN, and downregulation of Nav1.1 and Nav1.6 expression contributes to HF-induced SAN dysfunction. These findings provide additional information about molecular basis of disease-related impairment of SAN function.
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Affiliation(s)
- Yuan Du
- Department of Cardiovascular Medicine, First Hospital of Xi'an Jiaotong University, No. 277 West Yanta Road, Xi'an, Shaanxi, 710061, China
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Matsuyama TA, Inoue S, Tanno K, Makino M, Ogawa G, Sakai T, Kobayashi Y, Katagiri T, Ota H. Ectopic nodal structures in a patient with atrial tachycardia originating from the mitral valve annulus. Europace 2006; 8:977-9. [PMID: 17005590 DOI: 10.1093/europace/eul101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report a case, which we believe to be rare, of adenosine-sensitive atrial tachycardia (AT) originating from the mitral valve annulus. The patient, a 73-year-old woman, died of unrelated cause 4 years after radiofrequency (RF) ablation therapy. Histologically, fibrous replacement of atrial musculature by mature collagenous tissue produced by the RF current was observed at the left inferior atrioventricular junction. In serial sections that included the coronary sinus, two distinct nodal structures containing small, pale myocytes within the fibrous tissue matrix were identified around the region of the ablation lesion. Our case appears to be a unique representation of tissue that was associated with the occurrence and maintenance of AT.
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Affiliation(s)
- Taka-Aki Matsuyama
- Second Department of Pathology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
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Onciu M, Tuţă LA, Baz R, Leonte T. [Specifics of the blood supply of the sinoatrial node]. Rev Med Chir Soc Med Nat Iasi 2006; 110:667-73. [PMID: 17571564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The present study aims to identify the heart nodal system blood supply sources and especially those of the sinoatrial node. It included 50 unpreserved and preserved human hearts from subjects of both sexes (40 males and 10 females) aged 12 to 68, of Romanian (42) and non-Romanian origin (8). The used denominations are those recommended by DiDio & Wakefield, based on splitting of the atrial walls into four quadrants (right and left, both anterior and posterior) which are further divided into three parts (medial, middle and lateral). We used special dissection techniques and plastic mass injections followed by corrosion. Our results confirm the opinion shared by most authors, in favour of the predominance of the origin of sinoatrial node artery from the right coronary artery. The sinoatrial node was supplied by a unique source represented by the right coronary artery in 37 cases (74%) and by the circumflex artery in 8 cases (16%), and by a double source represented by two branches of the right coronary artery in 2 cases (4%) and of both coronary arteries in 3 cases (6%). The direct arterial branches to the sinoatrial node were represented mainly by the right anteromedial atrial artery with origin from the right coronary artery level with the medial third of the right anterior quadrant of the atrial wall. From the left coronary system, the left anteromedial artery is the one responsible with the sinoatrial node supply; the source is the circumflex artery and its origin is the medial third of the left anterior quadrant. Contrary to DiDio et al., we found in addition to the mainly unilateral blood supply, the bilateral one. We didn't find any case with a sinoatrial node artery originating from the trunk of the left coronary artery, or with an extracardiac origin. We may state there are no significant differences of the origin and distribution of the sinoatrial node artery related to sex or country of origin. Thus, we cannot fully confirm the theories about the influence of the general variation factors on the arterial origin. The atherosclerotic or thrombotic obstruction of the sinoatrial node artery may induce severe heart rhythm disturbances or even sudden death.
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Affiliation(s)
- M Onciu
- Universitatea Ovidius Constanţa, Facultatea de Mediciná
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Hurlé A, Climent V, Sánchez-Quintana D. Sinus node structural changes in patients with long-standing chronic atrial fibrillation. J Thorac Cardiovasc Surg 2006; 131:1394-5. [PMID: 16733176 DOI: 10.1016/j.jtcvs.2006.01.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Accepted: 01/30/2006] [Indexed: 10/24/2022]
Affiliation(s)
- Aquilino Hurlé
- Department of Cardiac Surgery, Hospital General Universitario de Alicante, Alicante, Spain.
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Ong MGY, Lee PC, Tai CT, Lin YJ, Lee KT, Tsao HM, Kuo JY, Chang SL, Hwang B, Chen SA. Coronary sinus morphology in different types of supraventricular tachycardias. J Interv Card Electrophysiol 2006; 15:21-6. [PMID: 16680546 DOI: 10.1007/s10840-006-7619-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Accepted: 02/05/2006] [Indexed: 11/28/2022]
Abstract
BACKGROUND Atrioventricular nodal reentry tachycardia (AVNRT) is based on the concept of dual AV node pathways that are functionally and anatomically distinct. The bigger coronary sinus ostium (CSO) in patients with AVNRT compared to other supraventricular tachycardias (SVTs) may produce separation of atrial inputs into the AV node or create anisotropic conduction, thus giving rise to a different AV nodal physiology. Previous studies measuring the size of the CSO using CS angiography between patients with AVNRT and other SVTs showed conflicting results. Besides, no previous studies have compared the CS morphology of the different forms of AVNRT. OBJECTIVES This study compares the size and morphology of the CS among patients with typical AVNRT, atypical AVNRT and accessory pathways mediated reentrant tachycardia (AVRT). METHODS Ninety-six patients with clinically documented SVTs were divided into three groups. The diameter of the CS was measured in LAO projection during end ventricular systole (by choosing the last ventricular inward motion). The CSO as well as 5, 10 and 15 mm inside the CS were measured. CS morphology is defined as either wind-sock shape or tubular shape. RESULTS The size of the CS ostium was 13.58 +/- 3.98, 15.93 +/- 4.86 and 12.50 +/- 2.83 mm for the atypical AVNRT, typical AVNRT and AVRT, respectively (p = 0.03). There was significant difference in the size of the CS from the ostium until 15 mm into the CS between 1) typical AVNRT and AVRT, 2) typical AVNRT and atypical AVNRT. Typical and atypical AVNRT patients had more windsock morphology CS (13/32, 40.6% and 10/32, 31.2%) compared to AVRT which had only one (1/32, 3.1%) windsock morphology (p = 0.002). CONCLUSION The easier CS cannulation in patients with typical AVNRT could be due to a bigger CS size and to a more windsock morphology. The CS size and morphology may be a very important substrate of tachycardia in patients with AVNRT.
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Tjandrawidjaja MC, Fu Y, Kim DH, Burton JR, Lindholm L, Armstrong PW. Compromised atrial coronary anatomy is associated with atrial arrhythmias and atrioventricular block complicating acute myocardial infarction. J Electrocardiol 2005; 38:271-8. [PMID: 16003715 DOI: 10.1016/j.jelectrocard.2005.01.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND The relevance of the atrial coronary anatomy in the pathogenesis of atrial arrhythmias and atrioventricular (AV) block complicating acute myocardial infarction (AMI) remains unclear. OBJECTIVES We evaluated the location of the infarct-related coronary lesion relative to the principal atrial branches (ie, sinoatrial nodal, AV nodal, left atrial circumflex) in 454 patients with ST-elevation AMI in the CAPTORS II trial. METHODS Patients underwent systematic 60-minute postfibrinolytic angiograms, and coronary anatomy was correlated with evidence of atrial arrhythmias and AV block on sequential electrocardiograms. RESULTS Patients with either sinoatrial nodal or left atrial circumflex compromise (n = 34) had a higher incidence of "early" (ie, up to 90 minutes postfibrinolysis) atrial arrhythmias vs those without (23.5% vs 7.1%; P = .004). Patients with AV nodal compromise (n = 207) had a higher incidence of "early" AV block vs those without (12.1% vs 3.6%; P = .001). CONCLUSION These findings support the etiological role of acute atrial ischemia in the development of early atrial arrhythmias and AV block complicating AMI.
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Sakabe M, Fujiki A, Nishida K, Sugao M, Nagasawa H, Tsuneda T, Mizumaki K, Inoue H. Enalapril Preserves Sinus Node Function in a Canine Atrial Fibrillation Model Induced by Rapid Atrial Pacing. J Cardiovasc Electrophysiol 2005; 16:1209-14. [PMID: 16302906 DOI: 10.1111/j.1540-8167.2005.50100.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
METHODS AND RESULTS Seventeen beagles were pretreated with either placebo (group I, n = 9) or enalapril 1 mg/kg/day (group II, n = 8) and paced at 500/min from the right atrial appendage for 4 weeks. Every week, corrected sinus node recovery time (CSNRT) and sinus cycle length (SCL) were measured. Quantitative analysis of interstitial fibrosis (IF) and adipose tissue (AT) in the SN was performed with Masson's trichrome stain, and apoptosis of the sinus nodal cells were detected with terminal deoxynucleotidyl transferase nick end-labeling. In group I, rapid atrial pacing prolonged both CSNRT and SCL. After 4 weeks of pacing, CSNRT and SCL were significantly shorter in group II (CSNRT, 410 +/- 37 msec; SCL, 426 +/- 34 msec) than in group I (CSNRT, 717 +/- 52 msec, P < 0.005; SCL, 568 +/- 73 msec, P < 0.05). Both IF and AT of the SN were greater in group I (IF, 9.7 +/- 1.9%; AT, 32.6 +/- 5.9%) than in seven sham dogs (IF, 2.4 +/- 0.9%, P < 0.05; AT, 4.0 +/- 1.7%, P < 0.05) and in group II dogs (IF, 4.0 +/- 2.0%, P < 0.05; AT, 4.0 +/- 1.7%, P < 0.05). End-labeling assay was positive in three of nine dogs in group I, but negative in group II and sham dogs. CONCLUSIONS Rapid atrial pacing impaired SN function through IF and AT of the SN. Enalapril prevented these pacing-induced degenerative changes and improved SN function.
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Affiliation(s)
- Masao Sakabe
- Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan
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Gillis AM, Koehler J, Morck M, Mehra R, Hettrick DA. High atrial antitachycardia pacing therapy efficacy is associated with a reduction in atrial tachyarrhythmia burden in a subset of patients with sinus node dysfunction and paroxysmal atrial fibrillation. Heart Rhythm 2005; 2:791-6. [PMID: 16051111 DOI: 10.1016/j.hrthm.2005.04.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Accepted: 04/23/2005] [Indexed: 11/30/2022]
Abstract
BACKGROUND Atrial tachycardia (AT) and atrial flutter that occur in association with paroxysmal atrial fibrillation (AF) can be successfully terminated by antitachycardia pacing (ATP) therapy. We hypothesized that atrial ATP therapy reduces AT/AF burden in a subset of patients with symptomatic bradycardia and frequent paroxysmal AT/AF. OBJECTIVES This study evaluated the effect of atrial ATP therapy on AT/AF burden in a pacemaker population with paroxysmal AF. METHODS We compared AT/AF burden in 261 patients who received a Medtronic AT500 pacemaker for treatment of AT/AF in the setting of symptomatic bradycardia based on device-classified atrial ATP efficacy < 60% and > or = 60%. Patients with > or = 10 device-detected episodes of AT/AF before and after atrial ATP therapy initiation were identified from four clinical studies performed in 72 centers worldwide. RESULTS The high efficacy group comprised 75 patients with atrial ATP efficacy > or = 60%. The low efficacy group comprised 186 patients with atrial ATP efficacy < 60%. AT/AF episode frequency was similar in both groups prior to ATP activation and decreased in the low efficacy group following ATP activation. Following atrial ATP initiation, total AT/AF burden increased slightly in the low ATP efficacy group (median 2.77 [25th-75th percentiles 0.84-5.86] hours/day vs 2.92 [0.59-8.12] hours/day, P = .01). In contrast, total AT/AF burden decreased significantly in the high efficacy group (median 2.46 [0.29-8.88] hours/day vs 0.68 [0.13-2.97] hours/day, P < .001). CONCLUSION Up to 30% of patients with frequent episodes of paroxysmal AF and symptomatic bradycardia experience a reduction in AT/AF burden from atrial ATP therapy over time.
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Affiliation(s)
- Anne M Gillis
- Libin Cardiovascular Institute of Alberta and Department of Cardiovascular Sciences, University of Calgary and Calgary Health Region, Calgary, Alberta, Canada.
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Stirbys P. Biological pacemaking: in our lifetime? Heart Rhythm 2005; 2:903-4. [PMID: 16051137 DOI: 10.1016/j.hrthm.2005.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2005] [Indexed: 11/22/2022]
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Abstract
A 30-year-old man with Brugada syndrome died suddenly. The heart weighed 380 g. The left ventricular wall showed mild thickening, and marked fatty tissue deposition was noted in the right ventricular outflow tract. Neither ventricle was enlarged. Contraction band necrosis was diffuse in both ventricles. In the ventricles no cardiac muscle cell hypertrophy or atrophy, or significant interstitial fibrosis was observed. In the sinus node the number of nodal cells was reduced by half, with fatty tissue and fibrosis prominent. But no lesions were evident in the right bundle branch.
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Affiliation(s)
- Shin-ichiro Morimoto
- Division of Cardiology, Department of Internal Medicine, Fujita Health University School of Medicine, Toyoake, Japan.
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Matturri L, Ottaviani G, Lavezzi AM, Rossi L. Early atherosclerotic lesions of the cardiac conduction system arteries in infants. Cardiovasc Pathol 2005; 13:276-81. [PMID: 15358342 DOI: 10.1016/j.carpath.2004.05.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Revised: 02/02/2004] [Accepted: 05/10/2004] [Indexed: 11/21/2022] Open
Abstract
INTRODUCTION Although several studies have described initial atherosclerotic lesions of the coronary arteries, already detectable in infancy and even during the intrauterine life, little, if any, attention has been given to the possible involvement of the cardiac conduction system arteries. In particular, to the best of our knowledge, none has considered the lesions of the cardiac conduction arteries as an initial stage of atherosclerosis. METHODS The cardiac conduction system of 70 infants dying suddenly and unexpectedly was removed in two blocks for paraffin embedding and serially cut. RESULTS The histological study of the cardiac conduction arteries of the 70 cases examined showed a normal structure in 55 cases (78.57%). In 15 cases (21.43%), there was a thickening of the sinoatrial node and/or atrioventricular artery associated with a thickening of varying severity in coronary artery walls. The lesions were marked by thickening and deposits of amorphous material and mainly lipids in the intima, as well as fragmentation of the elastic fiber system. A significant correlation was evident between early atherosclerotic lesions and both formula feeding and parental cigarette smoking (P<.05, chi(2) test). CONCLUSIONS The combination of both the considered risk factors seems to increase the early atherogenic effect of each noxa because the coronary lesions were more diffused in formula-fed infants whose parents both smoked.
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Affiliation(s)
- Luigi Matturri
- Institute of Pathology, University of Milan, Via della Commenda 19, 20122 Milan, Italy.
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Matsuyama TA, Inoue S, Kobayashi Y, Sakai T, Saito T, Katagiri T, Ota H. Anatomical diversity and age-related histological changes in the human right atrial posterolateral wall. Europace 2004; 6:307-15. [PMID: 15172655 DOI: 10.1016/j.eupc.2004.03.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Accepted: 03/28/2004] [Indexed: 11/29/2022] Open
Abstract
AIMS Recent clinical observations suggest that the right atrial posterolateral wall structures originate ectopic beats and function as anatomical obstacles. Because atrial arrhythmias increase in incidence after middle age, we investigated histological diversity and age-related changes in right atrial posterolateral wall. METHODS AND RESULTS Twenty-six autopsied hearts (mean 65.2 years, 16 men and 10 women) were studied. The entire posterolateral right atrium was cut serially. We determined the distribution of the sinoatrial node and localized it in relation to the crista terminalis and sinus venosus. We also compared histopathological changes in these tissues between three groups consisting of 31- to 50-year-old, 51- to 70-year-old and 71- to 90-year-old hearts. Total mean length of the crista terminalis, the sinoatrial node, and the sinus venosus was 46 mm, 21 mm and 29 mm, respectively, and showed no age-related changes, but the distribution of the sinoatrial node was varied. Mean muscular volume of the sinus venosus was significantly reduced in the two older groups, though that of the crista terminalis showed no age related-changes. CONCLUSION Histological diversity of the sinoatrial node and age-related changes in the sinus venosus beneath the sinoatrial node may enhance histological heterogeneity and hence arrhythmogenicity.
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Affiliation(s)
- Taka-aki Matsuyama
- Second Department of Pathology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan
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Abstract
Lewy bodies (LB) are characteristic pathological findings for idiopathic Parkinson disease, and extracranial organs have also been known to exhibit these structures. Clinically, the possible involvement of LB in cardiac dysfunction has attracted attention based on the findings of studies using [123I] metaiodobenzyl guanidine (MIBG) scintigraphy. The purpose of the present study was to investigate the possible involvement of LB in heart disease. A total of 40 autopsy cases consisting of Lewy body disease and Parkinson syndrome were examined. The former were cases with intracranial LB regardless of clinical symptoms, and the latter were cases with parkinsonism but without intracranial LB. The presence of heart disease or an atrial arrhythmia and the results of an MIBG scintigraphy study were clinically examined. The sinoatrial node was examined microscopically and immunohistochemically. The results showed that heart disease and atrial arrhythmia complications were more frequent in cases with Lewy body disease than in cases with Parkinson syndrome and that LB were frequently found in extracranial organs, especially in the sinoatrial nodal ganglion, in cases with Lewy body disease. In the current report, we hypothesized that neuronal changes involving LB in the sinoatrial nodal ganglion may cause arrhythmia and ischemic heart disease as a result of vasoconstriction.
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Affiliation(s)
- Yume Okada
- Department of Clinical Pathology, Tokyo Metropolitan Tama Geriatric Hospital, Tokyo, Japan.
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Abstract
The role of diastolic voltage oscillations in the initiation and maintenance of pacemaker discharge was studied in guinea pig-isolated sino-atrial (SA) node by means of a microelecrode technique. When [K(+)](o) is suitably increased, the maximum diastolic potential decreases and all action potentials (APs) assume the characteristics of dominant pacemakers (slow responses with U-shaped diastolic depolarization). Subsequently, as the slope and amplitude of diastolic depolarization (DD) decreases, the threshold is missed, unmasking the fused oscillatory potentials V(os) and ThV(os). As high [K(+)](o) perfusion continues, the oscillatory potentials become separated, V(os) following the AP and ThV(os) appearing later on, when DD enters a less negative voltage range (oscillatory zone). ThV(os) grow in amplitude and attain the threshold, thereby insuring a slow discharge. If [K(+)](o) is further increased, the smaller ThV(os) miss the threshold and SA node becomes quiescent. On reducing high [K(+)](o), ThV(os) re-appear, increase in size and initiate spontaneous discharge. As they occur progressively earlier during DD, ThV(os) eventually fuse with V(os): at that stage, DD appears to continue directly into the upstroke (U-shaped DD) and the oscillations are no longer seen. During recovery in Tyrode solution, size and slope of V(os) and of ThV(os) further increase and cause a faster discharge. When APs assume a subsidiary configuration, their DD (no longer U-shaped) abruptly terminates into the upstroke. In high [K(+)](o), increasing [Ca(2+)](o) or applying a fast drive increase the size and slope of V(os) and of ThV(os), which in turn restore or accelerate discharge. In contrast, low [Ca(2+)](o) abolishes V(os) and ThV(os) and causes SA node arrest. Low [Ni(2+)] (35.5 microM) increases the rate whereas high [Ni(2+)] (0.73 mM) stops the SA node. Ryanodine eliminates V(os) and ThV(os) and markedly slows or stops discharge. Thus, ThV(os) and V(os) are separate voltage oscillations that play an obligatory role in the initiation and maintenance of SA node discharge, V(os) by steepening early DD and ThV(os) by attaining the threshold in the dominant pacemaker range, either by gradually increasing during late DD at slow rates or by fusing with V(os) at fast rates. Both V(os) and ThV(os) are Ca(2+) dependent, but apparently in different ways.
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Affiliation(s)
- Michael P Nett
- Department of Physiology and Pharmacology, Downstate Medical Center, State University of New York, Box 31, 450 Clarkson Avenue, Brooklyn, NY 11203, USA
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Abstract
Congenital heart block (CHB) is a conduction abnormality characterized by complete atrioventricular (AV) block. CHB affects fetuses and/or newborn of mothers with autoantibodies reactive with ribonucleoproteins 48-kDa SSB/La, 52-kDa SSA/Ro, and 60-kDa SSA/Ro. We recently established animal models of CHB and reported, for the first time, significant sinus bradycardia preceding AV block. This unexpected observation implies that the spectrum of conduction abnormalities extends beyond the AV node to also affect the SA node. To test this hypothesis, we investigated the functional basis of this sinus bradycardia by characterizing the effects of antibodies from mothers with CHB children (positive IgG) on ionic currents that are known to significantly contribute to spontaneous pacing in SA node cells. We recorded L- (I(Ca.L)) and T- (I(Ca.T)) type Ca2+, delayed rectifier K+ (I(K)), hyperpolarization-activated (I(f)) currents, and action potentials (APs) from young rabbit SA node cells. We demonstrated that positive IgG significantly inhibited both I(Ca.T) and I(Ca.L) and induced sinus bradycardia but did not affect I(f) and I(K). Normal IgG from mothers with healthy children did not affect all the currents studied and APs. These results establish that IgG from mothers with CHB children causes substantial inhibition of I(Ca.T) and I(Ca.L), two important pacemaker currents in rabbit SA node cells and point to both I(Ca.T) and I(Ca.L) as major players in the ionic mechanism by which maternal antibodies induce sinus bradycardia in CHB. These novel findings have important clinical significance and suggest that sinus bradycardia may be a potential marker in the detection and prevention of CHB. The full text of this article is available online at http://circres.ahajournals.org
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MESH Headings
- Action Potentials
- Adult
- Animals
- Antibodies, Antinuclear/immunology
- Antibodies, Antinuclear/pharmacology
- Arrhythmia, Sinus/etiology
- Arrhythmia, Sinus/immunology
- Arrhythmia, Sinus/physiopathology
- Autoantigens
- Bradycardia/etiology
- Bradycardia/immunology
- Bradycardia/physiopathology
- Calcium/metabolism
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/physiology
- Calcium Channels, T-Type/drug effects
- Calcium Channels, T-Type/physiology
- Female
- Heart Block/complications
- Heart Block/congenital
- Heart Block/immunology
- Heart Block/physiopathology
- Humans
- Immunity, Maternally-Acquired
- Immunoglobulin G/immunology
- Immunoglobulin G/pharmacology
- Ion Transport/drug effects
- Pregnancy
- RNA, Small Cytoplasmic
- Rabbits
- Ribonucleoproteins/immunology
- Sinoatrial Node/pathology
- Sinoatrial Node/physiopathology
- SS-B Antigen
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Affiliation(s)
- Keli Hu
- Molecular and Cellular Cardiology Program, VA New York Harbor Healthcare System, SUNY Downstate Medical Center and NYU School of Medicine, Brooklyn, NY 11209, USA
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