Variations of the origin of the artery of the sinoatrial node in normal human hearts

Left atrial strain associated with interatrial block in patients with ST-segment elevation myocardial infarction

Both interatrial block (IAB) and left atrium (LA) strain are associated with atrial arrhythmias in ST-segment elevation myocardial infarction (STEMI) patients, but the relationship between IAB and LA strain has not yet been reported. This study was to investigate the correlation between LA strain and IAB in STEMI patients. This is a single-center retrospective clinical observational study. The STEMI patients with primary percutaneous coronary intervention (pPCI) were enrolled, and all patients completed cardiac magnetic resonance (CMR). A standard 12-lead electrocardiogram (ECG) was recorded on the same day as CMR. IAB was measured by p duration on ECG at follow-up. 302 patients were enrolled, including 91 (30.1%) with IAB. The reservoir strain, conduit strain and booster strain were included in model 1, model 2 and model 3, respectively. In model 1, age (OR 1.025; 95%CI 1.003-1.047; p = 0.026), hypertension (OR 2.188; 95%CI 1.288-3.719; p = 0.004), and reservoir strain (OR 0.947; 95%CI 0.920-0.974; p < 0.001) were independent factors for IAB. In model 2, age (OR 1.031; 95%CI 1.009-1.053; p = 0.006), hypertension (OR 2.058; 95%CI 1.202-3.522; p = 0.008), RCA lesions (OR 1.797; 95%CI 1.036-3.113; p = 0.037), and conduit strain (OR 0.910; 95%CI 0.868-0.953; p < 0.001) were independent factors for IAB. In model 3, age (OR 1.022; 95%CI 1.001-1.045; p = 0.044), hypertension (OR 2.239; 95%CI 1.329-3.773; p = 0.002), and booster strain (OR 0.948; 95%CI 0.908-0.991; p = 0.019) were independent factors for IAB. With the lowest AIC and BIC values, model 2 was the best-fit model. LA strain associated with IAB in STEMI patients. The model including conduit strain was the best-fit one.

Anatomical study of the cardiac conduction system in swine hearts

The cardiac conduction system (CCS) is crucial for regulating heartbeats; therefore, clinicians and comedicals involved in cardiovascular medicine treatment must have a thorough understanding of the CCS structure and function. However, anatomical education of the CCS based on actual dissection and observation is uncommon, although such educational methodology promotes three-dimensional structural understanding of the observed object. Based on previous studies, we examined the CCS structure in the heart of a swine (pig, Sus scrofa domestica) which has been used in the biological, medical and anatomical curricula as science teaching materials, by using macroscopic dissection procedures. Most CCS structures in a young pig heart were successfully identified and illustrated on a macroscopic scale. The atrioventricular bundle (His bundle) was located on the lower edge of the membranous interventricular septum and was clearly distinguished from the general myocardial fibres by its colour and fibre arrangement direction. Following the atrioventricular bundle towards the atrium or ventricle with properly removing the endocardium and myocardium, the atrioventricular node or the right and left bundles appeared respectively. In contrast, the sinoatrial node was not identified. The anatomy of the CCS in young pig hearts was essentially similar to that previously reported in humans and several domestic animals. Our findings of the CCS in young pig hearts are expected to be useful for medical and anatomical education for medical and comedical students, young clinicians and comedical workers.

Prevalence of anatomic variants in coronary arteries of Japanese Black cattle

Coronary artery anomalies that can cause sudden cardiac death have been described in some mammals. However, few studies have investigated coronary anomalies and coronary artery branching patterns in cattle. Therefore, understanding of bovine coronary arteries is incomplete. The aim of this study was to clarify anatomic variants in coronary arteries of Japanese Black cattle. The gross anatomy of the coronary arteries was examined in the hearts of 100 cattle. A total of 14 of 100 hearts exhibited confirmed coronary anomalies in the left main trunk. These 14 hearts were classified into 5 types potentially associated with cardiac ischemia. Regarding the coronary branches, the subsinuosal interventricular branch originated from the left circumflex branch (LCX) in 98 hearts and from the right coronary artery in 2 hearts. The origin of the sinoatrial nodal branch was classified into 3 types. In 99 hearts, the atrioventricular nodal branch originated from the LCX at the heart crux. This study characterized the prevalence of coronary anomalies, branching patterns of coronary arteries, and coronary artery anatomic variants in Japanese Black cattle.

Anatomy of the coronary arteries in fetal pigs: comparison with human anatomy

In this study, 94 fetal pigs were used to comprehensively investigate the origins, number, location, and distribution of the coronary arteries to enrich knowledge on the coronary circulation in fetal pigs, and allow comparison with adult pigs and humans. In fetal pigs, the posterior interventricular sulcus branch always arose from the right coronary artery and the circumflex artery was rarely extended to the posterior interventricular sulcus, while it is variable in humans. In fetal pigs, there was sometimes anastomosis (8.5%) between the left and right conus branches as nutrient arteries of the pulmonary cone. Other branches were not significantly different between fetal pigs and humans, including the acute marginal branch, obtuse marginal branch, and sinoatrial nodal artery. Coronary dominance was also similar. In conclusion, compared with adult pigs, dissection of the coronary arteries in fetal pigs provided a more faithful overview of the porcine coronary circulation. The coronary arteries in fetal pigs were also more suitable for comparison with humans when pigs are used as experimental animals for studying the coronary vessels, which could be an important reference for investigation of clinical treatment of the coronary arteries. In summary, our data provide reliable information about the distribution and ramifications of the coronary arteries, and could be useful for clinicians and surgeons who wish to comprehensively understand coronary anatomy.

Interatrial block as a predictor of atrial fibrillation in patients with ST-segment elevation myocardial infarction

INTRODUCTION

Interatrial block (IAB) is strongly associated with recurrence of atrial fibrillation (AF) in different clinical scenarios. Atrial fibrosis is considered the responsible mechanism underlying the pathogenesis of IAB. The aim of this study was to investigate whether IAB predicted AF at 12 months follow-up in a population of patients with ST segment elevation myocardial infarction (STEMI).

HYPOTHESIS

We aimed to investigate whether IAB predicted AF at 12 months follow up in a population of patients with STEMI.

METHODS

Prospective, single center, observational study of patients presenting with ST-segment elevation myocardial infarction (STEMI) and referred to primary percutaneous coronary intervention (P-PCI). Surface electrocardiograms (ECG) were recorded on admission and at 6th hour post P-PCI. Patients were screened for the occurrence of AF at a 12-months visit.

RESULTS

A total of 198 patients were included between September 2015 and September 2016. IAB (partial and advanced) was detected in 102 (51.5%) patients on admission. Remodeling of the P-wave and subsequent normalization reduced the prevalence of IAB to 47 (23.7%) patients at 6th hour. AF was detected in 17.7% of study patients at 12 months. Partial IAB (p-IAB) on admission (OR 5.10; 95% CI, 1.46-17.8; P = 0.011) and on 6th hour (OR 4.15; 95% CI, 1.29-13.4; P = 0.017), presence of a lesion in more than one coronary artery (OR 3.29; 95% CI, 1.32-8.16; P = 0.010) found to be independent predictors of AF at 12 months.

CONCLUSION

IAB is common in patients with STEMI and along with the presence of diffuse coronary artery disease is associated with new onset of AF.

Comparison of the Extent of Coronary Artery Disease in Patients With Versus Without Interatrial Block and Implications for New-Onset Atrial Fibrillation

Interatrial block (IAB) represents delay or block of conduction between the atria. IAB has been shown to predict the development or recurrence of atrial fibrillation (AF) in various clinical scenarios. Few studies have examined the correlation between coronary artery disease and the prevalence of IAB and its impact on AF. The aim of this study was to determine if specific coronary artery lesions (location and number) are associated with the presence of IAB and development of new-onset AF. Retrospective analysis of patients presenting with non-ST-segment elevation myocardial infarction (NSTEMI) to our institution. Data were recorded for clinical, echocardiographic, angiographic, electrocardiographic, and outcome variables. Semiautomatic calipers and scanned electrocardiograms at 300 DPI maximized × 8 were used to measure P-wave duration, with a follow-up for a minimum of 1 year. The chi-square and independent-sample t tests were done using IBM SPSS. A total of 322 patients were included in the analysis. Men 72.3%, mean age 65.4 ± 11.9 years, mean ejection fraction of 55.2 ± 12.7% and mean left atrial diameter of 38.7 ± 6 mm. The prevalence of partial IAB was 31.9%, and advanced IAB was 6.5%. Patients with IAB were significantly older (<0.001) and had a greater prevalence of hypertension (0.014). The presence of diffuse coronary artery disease defined as >1 significant coronary artery lesion was associated with IAB (0.026). No specific coronary artery lesion location was found to be associated with IAB nor increased P-wave duration. Patients who developed AF during the follow-up had a significantly higher prevalence of IAB (p = 0.021) and also higher prevalence of diffuse coronary artery disease (p = 0.001). IAB is significantly associated with diffuse coronary artery disease in patients with NSTEMI. IAB is significantly associated with the development of new-onset AF within 12 months after NSTEMI.

Anatomical Variations in the Sinoatrial Nodal Artery: A Meta-Analysis and Clinical Considerations

BACKGROUND AND OBJECTIVE

The sinoatrial nodal artery (SANa) is a highly variable vessel which supplies blood to the sinoatrial node (SAN). Due to its variability and susceptibility to iatrogenic injury, our study aimed to assess the anatomy of the SANa and determine the prevalence of its anatomical variations.

STUDY DESIGN

An extensive search of major electronic databases was performed to identify all articles reporting anatomical data on the SANa. No lower date limit or language restrictions were applied. Anatomical data regarding the artery were extracted and pooled into a meta-analysis.

RESULTS

Sixty-six studies (n = 21455 hearts) were included in the meta-analysis. The SANa usually arose as a single vessel with a pooled prevalence of 95.5% (95%CI:93.6-96.9). Duplication and triplication of the artery were also observed with pooled prevalence of 4.3% (95%CI:2.8-6.0) and 0.3% (95%CI:0-0.7), respectively. The most common origin of the SANa was from the right coronary artery (RCA), found in 68.0% (95%CI:55.6-68.9) of cases, followed by origin from the left circumflex artery, and origin from the left coronary artery with pooled prevalence of 22.1% (95%CI:15.0-26.2) and 2.7 (95%CI:0.7-5.2), respectively. A retrocaval course of the SANa was the most common course of the artery with a pooled prevalence of 47.1% (95%CI:36.0-55.5). The pooled prevalence of an S-shaped SANa was 7.6% (95%CI:2.9-14.1).

CONCLUSIONS

The SANa is most commonly reported as a single vessel, originating from the RCA, and taking a retrocaval course to reach the SAN. Knowledge of high risk anatomical variants of the SANa, such as an S-shaped artery, must be taken into account by surgeons to prevent iatrogenic injuries. Specifically, interventional or cardiosurgical procedures, such as the Cox maze procedure for atrial fibrillation, open heart surgeries through the right atrium or intraoperative cross-clamping or dissection procedures during mitral valve surgery using the septal approach can all potentiate the risk for injury in the setting of high-risk morphological variants of the SANa.

Morphological study of the sinus node and its artery in yak

The sinus node of yak has been studied by the histological methods and transmission electron microscopy. The sinus node artery of yak was also determined by the injection-corrosion casting technique, the angiography, and histological methods. The results showed that the sinus node of yak contained an extensive framework of collagen and two main type cells: pacemaker cells (P cells) and transitional cells (T cells). The P cells had a perinuclear clear zone, contained less myofibrils, and appeared smaller mitochondria than T cells. The T cells were longer and slender than P cells, and had a variety of shapes. At the periphery of sinus node there were many nerve fibers and ganglions. Gap junction did not reveal reaction with anti-connexin43, but it was detected by electron microscopy in the central part of sinus node of yak. The sinus node artery of yak originated from left coronary artery more frequently (98%) than by right (2%). The artery located at the periphery of sinus node. It had an internal elastic membrane throughout its course, and a large nerve bundle was found running in a longitudinal direction.

Análise comparativa entre a vascularização ventricular e do nó sinoatrial em gatos

A possível existência de interdependência na nutrição de territórios atriais e ventriculares tem sido objeto de preocupação por partes dos cardiologistas, especialmente no que tange a vascularização do nó sinoatrial e sua dependência apenas de uma artéria coronária ou de ambas e de sua relação com o predomínio destes vasos na vascularização ventricular. Assim, este estudo objetiva avaliar a relação da irrigação do nó sinoatrial e a origem e a predominância das artérias coronárias na vascularização dos ventrículos, para tanto utilizou-se 30 corações de gatos sem raça definida adultos, machos e fêmeas, sem sinais de afecção cardíaca. Os corações foram injetados pela aorta torácica com Neoprene Latex 450, corados com pigmento vermelho e dissecados posteriormente. Verificou-se que quando ocorria predomínio da vascularização ventricular do tipo esquerda (63,34%) a irrigação do nó sinoatrial ficou predominantemente na dependência do ramo proximal atrial direito (78,9%) ou com menor freqüência pelo ramo proximal atrial esquerdo (21,1%). Na vascularização ventricular do tipo equilibrada (33,34%), a irrigação do sinoatrial ficou na dependência mais freqüentemente do ramo proximal atrial direito (80%), ou com menor freqüência a nutrição do nó se deu pelo ramo proximal atrial esquerdo (20%). Em um caso isolado, ocorreu a vascularização ventricular do tipo direita (3,34%), a nutrição do sinoatrial, ficou na dependência exclusiva do ramo intermédio atrial direito. Estes resultados indicam que nesta espécie não existe relação entre a irrigação do nó sinoatrial e o tipo de vascularização ventricular, independentemente do sexo.

Atrial Coronary Arteries: Anatomy And Atrial Perfusion Territories

Coronary anatomy has traditionally focused on ventricular circulation. This is largely due to the extent to which coronary artery disease contributes to ischemic heart disease through ventricular myocardial damage. Atrial fibrillation and other tachyarrhythmias that involve the atria, however, remain a major cause of morbidity and mortality. In order to increase mechanistic research and therapeutic interventional procedures for diseases of the atria, an optimal knowledge of atrial anatomy is necessary. While substantial clarity exists regarding the distribution of nerve terminals and the organization of muscle bundles, the anatomy of coronary atrial circulation remains understudied. Historically, the high anatomical variability of atrial coronary branches led to unstandardized nomenclature in the literature. In this review, we delineate the anatomic courses of key atrial coronary branches and their perfusion territories, clarify their nomenclature, and propose unifying anatomical concepts of atrial circulation that we believe to be critical to the success of modern electrophysiologic and surgical procedures.

Anatomical bases of the surgical dissection of the interatrial septum: a morphological and histological study

BACKGROUND

The interatrial septum (IAS) can be dissected to resect pulmonary tumors invading the left atrium. The aim of this study was to describe the dissected structures, and to expose the benefits, the limits, and the embryologic reasons of such dissection.

METHODS

We dissected the IAS of 11 fresh, non-embalmed human hearts. The dissected structures were described and the length and depth of the dissection were measured. A histological study was performed in four other fresh hearts to identify and differentiate between dissectible and non-dissectible structures.

RESULTS

The dissection was performed through a fatty tissue located between two muscular walls. The depth limit of the IAS dissection was identified as the limbus of the fossa ovalis and the muscular roof of the atria. The section of the latter doubles the depth of the dissection at the level of the upper pulmonary veins. Mean length of the dissected IAS was 77 mm (55-90). Mean depths of the IAS were 41 mm (35-50) at the level of the left upper pulmonary vein, 27 mm (12-35) between the upper and lower pulmonary veins, and 14 mm (8-20) at the level of the left inferior pulmonary vein

CONCLUSION

The surgical dissection of the IAS is performed through the septum secundum that appears as an infold of the atrial wall. The length of the resectable left atrial cuff reaches a mean of 40 mm at the level of the upper pulmonary vein.

Vascularização arterial da região do nó sinoatrial em corações suínos: origem, distribuição e quantificação

O nó sinoatrial, por se encontrar topograficamente instalado como componente inicial do sistema de condução, é responsável pela geração dos impulsos nervosos determinantes da contração cardíaca. Estudos relacionados à morfologia do nó, visando conhecer a origem, trajeto e distribuição dos vasos neste tecido são conhecidos, contudo, no que diz respeito a estes aspectos e aos dados quantitativos da irrigação nodal, no que se refere ao comportamento vascular arterial e a densidade vascular arterial desta região, a literatura é escassa. Com este objetivo foram utilizados 30 corações de suínos SRD, sendo 27 injetados com resina vinílica corada, para análise da origem e trajeto da ANSA (artéria do nó sinoatrial) e 3 corações injetados com solução aquosa de carvão coloidal (tinta nanquim) para proceder à análise estereológica. As artérias atriais originaram-se tanto da artéria coronária direita quanto da esquerda, com predominância da primeira (66,66% e 33,33%, respectivamente). Quando originada da coronária direita, a irrigação ocorreu pelo ramo AADAM (artéria atrial direita cranial medial) em 14 casos e pelos ramos AADAI (artéria atrial direita cranial medial) em 2 casos e AADAL (artéria atrial direita cranial lateral) em 2 casos. Em 9 casos (33,33%) originou-se pela artéria coronária esquerda: quatro pelo ramo AASPL (artéria atrial esquerda caudal lateral), dois pelo ramo AASAI (artéria atrial esquerda cranial intermédia) e três pelo ramo AASAM (artéria atrial esquerda cranial medial). Anastomoses interarteriais, com participação dos vasos responsáveis pela irrigação do território do nó sinoatrial foram observadas na maioria dos casos (25 corações). O Volume do órgão ou Volume Referência (V(ref)) foi de 35,32x10(4)µm³. Para as variáveis estereológicas analisadas, a estimação da densidade de comprimento do vaso (Lv) foi de 766; o comprimento do vaso (L) - mm - foi de 27,06x10(5)µm; a densidade de superfície de área (Sv) foi de 182 e a superfície de área (S) - mm² - foi de 64,3x10(6)µm². A estimação da densidade numérica vascular (Nv(vasc)), quantidade de vasos por unidade de volume (cm³), foi de 2,19 10-5 e o número total de vasos no órgão (N(vasc)), estimado pelo método dissector físico em combinação com a estimativa do número de Euler (Xv), foi de 773,6832 x10-2. A elevada densidade vascular e do número total de vasos na região do nó sinoatrial de suínos sugere a existência de uma complexa e densa rede vascular perinodal, ratificando a importância deste marca-passo pelo seu suprimento sangüíneo.

Anatomy of the heart at multidetector CT: what the radiologist needs to know

Continued improvements in multidetector computed tomographic (CT) scanners have made cardiac CT an important clinical tool that is revolutionizing cardiac imaging. Multidetector CT with submillimeter collimation and gantry rotation times under 0.5 seconds allows the acquisition of studies with high temporal resolution and isotropic voxels. The volumetric data set that is generated can be analyzed with a depth previously not possible, requiring a solid understanding of the cardiac anatomy and its appearance on CT scans and postprocessed images.