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The involvement of gap junctions in the delayed phase of the protection induced by cardiac pacing in dogs. Clin Sci (Lond) 2012; 123:39-51. [DOI: 10.1042/cs20110501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The present study has examined the role of GJ (gap junctions) in the delayed anti-arrhythmic effect of cardiac pacing, with particular reference to the time-course changes in Cx43 (connexin43) expression both after pacing (4×5 min, at a rate of 240 beats/min) and 24 h later, when the dogs were subjected to a 25 min occlusion and reperfusion of the LAD (left anterior descending coronary artery). Compared with the SP (sham-paced) controls (n=20), in dogs paced 24 h previously (n=16) there were reductions in arrhythmia severity [e.g. number of VPB (ventricular premature beats) during occlusion 294±78 compared with 63±25; survival from the combined ischaemia/reperfusion insult 20% compared with 78%], and in other ischaemic changes [epicardial ST-segment, TAT (total activation time) and tissue impedance]. Pacing also prevented the ischaemia-induced structural impairment of the intercalated discs, and preserved GJ permeability and Cx43 phosphorylation, without modifying Cx43 protein content. Following cardiac pacing the membrane and total Cx43 protein contents were unchanged up to 6 h, but were significantly reduced 12 h later (preceded by a down-regulation of Cx43 mRNA at 6 h), and returned to normal by 24 h. Interestingly, dogs that were subjected to ischaemia 12 h after cardiac pacing showed increased arrhythmia generation. We conclude that cardiac pacing results in time-dependent changes in Cx43 expression, which may alter GJ function and influence arrhythmia generation during a subsequent ischaemia/reperfusion insult. This effect is manifested in protection 24 h after pacing, but of potential clinical interest is the finding that there is a time interval after pacing during which an ischaemic event may generate severe ventricular arrhythmias.
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Lengyel C, Orosz A, Hegyi P, Komka Z, Udvardy A, Bosnyák E, Trájer E, Pavlik G, Tóth M, Wittmann T, Papp JG, Varró A, Baczkó I. Increased short-term variability of the QT interval in professional soccer players: possible implications for arrhythmia prediction. PLoS One 2011; 6:e18751. [PMID: 21526208 PMCID: PMC3078143 DOI: 10.1371/journal.pone.0018751] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 03/17/2011] [Indexed: 12/12/2022] Open
Abstract
Background Sudden cardiac death in competitive athletes is rare but it is significantly more frequent than in the normal population. The exact cause is seldom established and is mostly attributed to ventricular fibrillation. Myocardial hypertrophy and slow heart rate, both characteristic changes in top athletes in response to physical conditioning, could be associated with increased propensity for ventricular arrhythmias. We investigated conventional ECG parameters and temporal short-term beat-to-beat variability of repolarization (STVQT), a presumptive novel parameter for arrhythmia prediction, in professional soccer players. Methods Five-minute 12-lead electrocardiograms were recorded from professional soccer players (n = 76, all males, age 22.0±0.61 years) and age-matched healthy volunteers who do not participate in competitive sports (n = 76, all males, age 22.0±0.54 years). The ECGs were digitized and evaluated off-line. The temporal instability of beat-to-beat heart rate and repolarization were characterized by the calculation of short-term variability of the RR and QT intervals. Results Heart rate was significantly lower in professional soccer players at rest (61±1.2 vs. 72±1.5/min in controls). The QT interval was prolonged in players at rest (419±3.1 vs. 390±3.6 in controls, p<0.001). QTc was significantly longer in players compared to controls calculated with Fridericia and Hodges correction formulas. Importantly, STVQT was significantly higher in players both at rest and immediately after the game compared to controls (4.8±0.14 and 4.3±0.14 vs. 3.5±0.10 ms, both p<0.001, respectively). Conclusions STVQT is significantly higher in professional soccer players compared to age-matched controls, however, further studies are needed to relate this finding to increased arrhythmia propensity in this population.
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Affiliation(s)
- Csaba Lengyel
- 1st Department of Internal Medicine, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Andrea Orosz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Péter Hegyi
- 1st Department of Internal Medicine, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Zsolt Komka
- Department of Health Sciences and Sports Medicine, Faculty of Physical Education and Sports Sciences, Semmelweis University, Budapest, Hungary
| | - Anna Udvardy
- Department of Health Sciences and Sports Medicine, Faculty of Physical Education and Sports Sciences, Semmelweis University, Budapest, Hungary
| | - Edit Bosnyák
- Department of Health Sciences and Sports Medicine, Faculty of Physical Education and Sports Sciences, Semmelweis University, Budapest, Hungary
| | - Emese Trájer
- Department of Health Sciences and Sports Medicine, Faculty of Physical Education and Sports Sciences, Semmelweis University, Budapest, Hungary
| | - Gábor Pavlik
- Department of Health Sciences and Sports Medicine, Faculty of Physical Education and Sports Sciences, Semmelweis University, Budapest, Hungary
| | - Miklós Tóth
- Department of Health Sciences and Sports Medicine, Faculty of Physical Education and Sports Sciences, Semmelweis University, Budapest, Hungary
| | - Tibor Wittmann
- 1st Department of Internal Medicine, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Julius Gy. Papp
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
- Division of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
- Division of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
- * E-mail:
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Varró A, Baczkó I. Possible mechanisms of sudden cardiac death in top athletes: a basic cardiac electrophysiological point of view. Pflugers Arch 2010; 460:31-40. [PMID: 20186549 DOI: 10.1007/s00424-010-0798-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 02/01/2010] [Accepted: 02/03/2010] [Indexed: 10/19/2022]
Abstract
Sudden death among athletes is very rare (1:50,000-1:100,000 annually) but it is still 2-4 times more frequent than in the age-matched control population and attracts significant media attention. We propose a mechanism underlying sudden cardiac death in athletes that does not relate to myocardial ischemia but is based on repolarization abnormalities due to potassium channel downregulation and can also be best explained by the concurrent presence of several factors such as cardiac hypertrophy (athlete's heart), and/or hypertrophic cardiomyopathy, increased sympathetic tone, genetic defects, drugs, doping agents, food, or dietary ingredients. These factors together can increase the repolarization inhomogeneity of the heart ("substrate") and an otherwise harmless extrasystole ("trigger") occurring with a very unfortunate timing may sometimes induce life-threatening arrhythmias. The effective and possible prevention of sudden cardiac death requires the development of novel cost effective cardiac electrophysiological screening methods. Athletes identified by these tests as individuals at higher proarrhythmic risk should then be subjected to more costly genetic tests in order to uncover possible underlying genetic causes for alterations in ionic channel structure and/or function.
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Affiliation(s)
- András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6720, Szeged, Hungary.
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Lascano EC, Valle HFD, Negroni JA. Nitroglycerin induces late preconditioning against arrhythmias but not stunning in conscious sheep. SCAND CARDIOVASC J 2009; 41:160-6. [PMID: 17487765 DOI: 10.1080/14017430701329295] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVES Nitroglycerin, a nitric oxide donor, induces late preconditioning against stunning by short ischemia-reperfusion periods. The study purpose was to assess similar nitroglycerin protection against stunning and arrhythmias produced by prolonged reversible ischemia. DESIGN Four groups of conscious sheep were studied, control: 12 minutes ischemia and 2 hour reperfusion; late preconditioning: six periods of 5 min ischemia-5 min reperfusion 24 h before 12 min ischemia and late preconditioning with 120 microg/kg and 600 microg/kg nitroglycerin administered instead of the ischemia-reperfusion periods. RESULTS Although late preconditioning protected against stunning (mean postischemic recovery of wall thickening fraction, control (n=10): 54.8+/-3.2, late preconditioning (n=9): 74.4+/-3.0, p<0.01), nitroglycerin 120 microg/kg (n=6) did not reproduce mechanical protection (50.1+/-3.8), even with a higher concentration of 600 microg/kg (59.1+/-3.7, n=4). However, nitroglycerin decreased arrhythmia severity index (control: 2.3+/-0.6, late preconditioning: 0.5+/-0.4, nitroglycerin 120 microg/kg: 1+/-0.4 and 600 microg/kg: 0.1+/-0.1 (p<0.05 vs. control). CONCLUSIONS Nitroglycerin only has a limited late preconditioning protective effect in conscious animals submitted to a reversible prolonged ischemia since it protects against arrhythmias but not against stunning.
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Affiliation(s)
- Elena C Lascano
- Department of Physiology, Pharmacology and Biochemistry, Favaloro University, Buenos Aires, Argentina.
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Hajnal A, Nagy O, Litvai A, Papp J, Parratt JR, Végh A. Nitric oxide involvement in the delayed antiarrhythmic effect of treadmill exercise in dogs. Life Sci 2005; 77:1960-71. [PMID: 15907332 DOI: 10.1016/j.lfs.2005.02.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Accepted: 02/03/2005] [Indexed: 11/22/2022]
Abstract
We have shown previously that a single period of treadmill exercise in dogs protects the heart against the severe ventricular arrhythmias that arise when a major (anterior descending) branch of the left coronary artery is occluded following anaesthesia 24 h later. This protection is aminoguanidine sensitive, suggesting a role for nitric oxide (NO) in this exercise-induced delayed antiarrhythmic effect. The present study has further examined the possible role of NO as a mediator and/or as a trigger using the selective induced (iNOS) inhibitor S-(2-aminoethyl)-methyl-isothiourea (AEST) and the specific but not selective nitric oxide synthase inhibitor N(omega)-nitro-L-arginine-methyl-ester (L-NAME). Exercise markedly reduced the severity of ischaemia and reperfusion-induced ventricular arrhythmias 24 h later. Thus, only one of the dogs (8%) so exercised fibrillated on occlusion (contrast 46% in the control, non-exercised dogs; P<0.05) and the marked changes in the inhomogeneity of electrical activation that occur in the ischaemic region following occlusion were much reduced (P<0.05 compared to controls). This delayed exercise-induced cardioprotection was significantly attenuated by the nitric oxide synthase (NOS) inhibitors L-NAME, given prior to the exercise protocol and by AEST given prior to the coronary artery occlusion. For example, survival from the ischaemia-reperfusion insult was 54% in the exercise dogs, 0% in the controls and 14% in those dogs given a NOS inhibitor. We conclude that nitric oxide (NO) is both the trigger and the mediator of this delayed protection against ischaemia and reperfusion-induced arrhythmias.
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Affiliation(s)
- Agnes Hajnal
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert Szent-Györgyi Faculty of Medicine, Dóm tér 12, P.O. Box 427, H-6701 Hungary
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Végh Á, Parratt JR. A common mechanism in the protective effects of preconditioning, cardiac pacing and physical exercise against ischemia and reperfusion-induced arrhythmias. Exp Clin Cardiol 2005; 10:200-205. [PMID: 19641688 PMCID: PMC2716252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Ischemic preconditioning results not only in a reduction in myocardial ischemic damage, but also in a marked suppression of those ventricular arrhythmias that result from a more prolonged period of ischemia and reperfusion insult. This protection is time-dependent and occurs in two distinct phases. There is an 'early phase' which is apparent immediately after the preconditioning stimulus but fades quickly (within 1 h to 2 h), and a 'delayed protection phase' in which the antiarrhythmic protection reappears 20 h to 24 h later. In both phases, the intensity of protection largely depends on the nature of the preconditioning stimulus. This can be ischemia resulting from brief coronary artery occlusions, cardiac pacing or vigorous physical exercise. Both cardiac pacing and exercise results in a marked reduction in the incidence and severity of ischemia and reperfusion-induced ventricular arrhythmias 24 h later. Although the precise mechanisms of the delayed protection that results from cardiac pacing and exercise are not yet fully understood, there is some evidence that similar endogenous protective substances (such as bradykinin, prostanoids and nitric oxide), as with ischemic preconditioning, play a pivotal trigger and mediator role in this anti-arrhythmic protection.
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Affiliation(s)
- Ágnes Végh
- Correspondence: Dr Ágnes Végh, Department of Pharmacology and Pharmacotherapy, Albert Szent Györgyi Medical Center, University of Szeged, Dóm tér 12, PO Box 115, H-6701 Szeged, Hungary. Telephone 366-254-5673, fax 366-254-5680, e-mail
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Hamilton KL, Quindry JC, French JP, Staib J, Hughes J, Mehta JL, Powers SK. MnSOD antisense treatment and exercise-induced protection against arrhythmias. Free Radic Biol Med 2004; 37:1360-8. [PMID: 15454275 DOI: 10.1016/j.freeradbiomed.2004.07.025] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2003] [Revised: 07/08/2004] [Accepted: 07/22/2004] [Indexed: 11/26/2022]
Abstract
Exercise provides protection against ischemia-reperfusion (I-R)-induced arrhythmias, myocardial stunning, and infarction. An exercise-induced increase in myocardial manganese superoxide dismutase (MnSOD) activity has been reported to be vital for protection against infarction. However, whether MnSOD is essential for exercise-induced protection against ventricular arrhythmias is unknown. We determined the effects of preventing the exercise-induced increase in MnSOD activity on arrhythmias during I-R resulting in myocardial stunning. Male rats remained sedentary or were subjected to successive bouts of endurance exercise. During in vivo myocardial I-R, the incidence of arrhythmias was significantly lower in the exercise-trained rats than in the sedentary rats as evidenced by the arrhythmia. When exercised rats were pretreated with antisense oligonucleotides directed against MnSOD, protection from arrhythmias was attenuated. Moreover, I-R resulted in significant increases in nitro-tyrosine (NT) in the sedentary group. Exercise abolished this I-R-induced NT formation but this protection was unchanged by antisense treatment. Protein carbonyls were increased by I-R, but neither exercise nor antisense treatment impacted carbonyl formation. These data demonstrate that an exercise-induced increase in MnSOD activity is important for protection against arrhythmias. The mechanism by which MnSOD provides protection does not appear to be linked to protein nitrosylation or oxidation.
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Affiliation(s)
- Karyn L Hamilton
- Department of Exercise and Sport Sciences, Center for Exercise Science, University of Florida Gainesville, FL 32611, USA.
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Nagy O, Hajnal Á, Parratt JR, Végh Á. Sildenafil (Viagra) reduces arrhythmia severity during ischaemia 24 h after oral administration in dogs. Br J Pharmacol 2004; 141:549-51. [PMID: 14744808 PMCID: PMC1574240 DOI: 10.1038/sj.bjp.0705658] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Sildenafil (Viagra) prolongs repolarisation in cardiac muscle, an effect that could lead to ventricular fibrillation (VF). Sildenafil (2 mg kg(-1)) was given by mouth to 12 mongrel dogs and, 24 h later, these dogs were anaesthetised, thoracotomised and subjected to a 25 min occlusion of the anterior descending coronary artery. Haemodynamic parameters were similar in this and the control group, but there were fewer and less serious ventricular arrhythmias during occlusion in the sildenafil group (VF 17 vs 60%; ventricular premature beats 140+/-52 vs 437+/-127% and episodes of ventricular tachycardia 4.0+/-3.2 vs 19.3+/-7.7%, all P<0.05). However, reperfusion VF and indices of ischaemia severity (epicardial ST-segment mapping, inhomogeneity) were not modified by the drug. Sildenafil increased the QT interval, especially during ischaemia. Our conclusion is that ischaemia-induced ventricular arrhythmias are reduced by sildenafil, but this protection is less pronounced than that following cardiac pacing or exercise.
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Affiliation(s)
- Orsolya Nagy
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert Szent-Györgyi Faculty of Medicine, Dóm tér 12, PO Box 427, H-6701 Hungary
| | - Ágnes Hajnal
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert Szent-Györgyi Faculty of Medicine, Dóm tér 12, PO Box 427, H-6701 Hungary
| | - James R Parratt
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert Szent-Györgyi Faculty of Medicine, Dóm tér 12, PO Box 427, H-6701 Hungary
| | - Ágnes Végh
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert Szent-Györgyi Faculty of Medicine, Dóm tér 12, PO Box 427, H-6701 Hungary
- Author for correspondence:
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Wu ZK, Iivainen T, Pehkonen E, Laurikka J, Tarkka MR. Perioperative and postoperative arrhythmia in three-vessel coronary artery disease patients and antiarrhythmic effects of ischemic preconditioning. Eur J Cardiothorac Surg 2003; 23:578-84. [PMID: 12694779 DOI: 10.1016/s1010-7940(03)00007-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
OBJECTIVE Sudden cardiac death caused by arrhythmia remains a major unsolved problem after coronary artery bypass grafting (CABG). Ischemic preconditioning (IP) has proved effective in suppressing ischemia reperfusion arrhythmias in animals and humans. The purpose of the present study was to establish whether IP reduces postoperative arrhythmias in three-vessel coronary artery disease patients undergoing CABG. METHODS Forty-five patients with stable angina and three main coronary artery stenosis admitted for primary CABG surgery were randomized into an IP and a control group. The IP protocol entailed twice occluding the ascending aorta by cross-clamping for 2 min, followed by 3 min of reperfusion. Electrocardiography was continuously recorded from the day before surgery to the second postoperative day. RESULTS During the recording, all patients developed SVES and VES after the operation. The incidences of SVT and ventricular tachycardia (VT) after surgery were 73.3 and 77.8%, respectively. IP significantly reduced VES events per hour during 2h after reperfusion. The SVT and VT incidence and events per hour were significantly lower in the IP group during 2h after reperfusion and 24h later. CONCLUSIONS IP significantly reduced VES, SVT, and VT after surgery. The antiarrhythmic effect 24h after surgery indicates a delayed antiarrhythmic IP phenomenon in these patients. These findings would indicate that IP constitutes a potential additional myocardial protective strategy in multi-vessel diseased patients undergoing CABG.
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Affiliation(s)
- Zhong-Kai Wu
- Division of Cardiac Surgery, Department of Surgery, Tampere University Hospital, 33521 Tampere, Finland
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Brutsaert DL. Cardiac endothelial-myocardial signaling: its role in cardiac growth, contractile performance, and rhythmicity. Physiol Rev 2003; 83:59-115. [PMID: 12506127 DOI: 10.1152/physrev.00017.2002] [Citation(s) in RCA: 500] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Experimental work during the past 15 years has demonstrated that endothelial cells in the heart play an obligatory role in regulating and maintaining cardiac function, in particular, at the endocardium and in the myocardial capillaries where endothelial cells directly interact with adjacent cardiomyocytes. The emerging field of targeted gene manipulation has led to the contention that cardiac endothelial-cardiomyocytal interaction is a prerequisite for normal cardiac development and growth. Some of the molecular mechanisms and cellular signals governing this interaction, such as neuregulin, vascular endothelial growth factor, and angiopoietin, continue to maintain phenotype and survival of cardiomyocytes in the adult heart. Cardiac endothelial cells, like vascular endothelial cells, also express and release a variety of auto- and paracrine agents, such as nitric oxide, endothelin, prostaglandin I(2), and angiotensin II, which directly influence cardiac metabolism, growth, contractile performance, and rhythmicity of the adult heart. The synthesis, secretion, and, most importantly, the activities of these endothelium-derived substances in the heart are closely linked, interrelated, and interactive. It may therefore be simplistic to try and define their properties independently from one another. Moreover, in relation specifically to the endocardial endothelium, an active transendothelial physicochemical gradient for various ions, or blood-heart barrier, has been demonstrated. Linkage of this blood-heart barrier to the various other endothelium-mediated signaling pathways or to the putative vascular endothelium-derived hyperpolarizing factors remains to be determined. At the early stages of cardiac failure, all major cardiovascular risk factors may cause cardiac endothelial activation as an adaptive response often followed by cardiac endothelial dysfunction. Because of the interdependency of all endothelial signaling pathways, activation or disturbance of any will necessarily affect the others leading to a disturbance of their normal balance, leading to further progression of cardiac failure.
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Wu ZK, Iivainen T, Pehkonen E, Laurikka J, Tarkka MR. Ischemic preconditioning suppresses ventricular tachyarrhythmias after myocardial revascularization. Circulation 2002; 106:3091-6. [PMID: 12473557 DOI: 10.1161/01.cir.0000041430.32233.5b] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Ventricular fibrillation (VF) and tachycardia (VT) are the common and potential life-threatening complications after CABG. Ischemic preconditioning (IP) has been proved effective in reducing ischemia reperfusion arrhythmia in animals and humans. Whether IP is effective in suppressing postoperative VF/VT in patients with CABG has not been studied. METHODS AND RESULTS Eighty-six patients with CABG with stable and unstable 3-vessel disease were equally randomly assigned into an IP and a control group. The patients who received IP received 2 periods of 2-minute ischemia followed by 3-minute reperfusion. Twenty-four-hour electrocardiographic data were collected. IP resulted in fewer cases of VF after declamping (48.8% versus 79.1% in IP and control, P=0.004) and a shorter VF period (2.28+/-0.44 versus 4.41+/-0.51 minutes, P=0.002). The episodes of VT were significantly reduced in patients in the IP group during early reperfusion and 24 hours after reperfusion (0.65+/-0.16 versus 3.71+/-0.46, P=0.000 and 0.07+/-0.04 versus 2.12+/-1.41, P=0.002, respectively). De novo sustained VT occurred in 3 control patients as against none in the IP group after surgery. As a result, IP significantly curtailed the mechanical ventilation period and reduced the need for inotropes. CONCLUSIONS IP significantly reduced postoperative VF/VT in patients with CABG with 3-vessel disease. Suppression of VT during early reperfusion and 24 hours after reperfusion suggests early and delayed IP phenomena in patients undergoing CABG surgery.
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Affiliation(s)
- Zhong-Kai Wu
- Division of Cardiac Surgery, Department of Surgery, Tampere University Hospital, Tampere, Finland
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Végh A, György K, Rastegar MA, Papp JG, Parratt JR. Delayed protection against ventricular arrhythmias by monophosphoryl lipid-A in a canine model of ischaemia and reperfusion. Eur J Pharmacol 1999; 382:81-90. [PMID: 10528142 DOI: 10.1016/s0014-2999(99)00557-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bacterial endotoxin reduces the severity of ventricular arrhythmias which occur when a coronary artery is occluded several hours later. We have now examined in anaesthetised dogs the effects on ischaemia and reperfusion-induced arrhythmias, of a non-toxic derivative component of the endotoxin molecule of the lipid-A (monophosphoryl lipid-A). This was given intravenously, in doses of 10 and 100 microg kg(-1), 24 h prior to coronary artery occlusion. Arrhythmia severity was markedly reduced by monophosphoryl lipid-A. During ischaemia, ventricular premature beats were reduced from 315+/-84 in the vehicle controls to 89+/-60 (with the lower dose of monophosphoryl lipid-A) and 53+/-23 (P<0.05) with the higher dose. The incidence of ventricular tachycardia was reduced from 75% to 25% (P<0.05) and 31% (P<0.05), and the number of episodes of ventricular tachycardia from 13.4+/-4.9 per dog to 1.1+/-1.1 (P<0.05) and 1. 2+/-0.9 (P<0.05) after doses of 10 and 100 microg kg(-1), respectively. The incidence of ventricular fibrillation during occlusion and reperfusion in the control group was 96% (15/16), i.e., only 6% (1/16) dogs survived the combined ischaemia-reperfusion insult. Monophosphoryl lipid-A (100 microg kg(-1)) significantly reduced the incidence of occlusion-induced ventricular fibrillation (from 50% to 7%; P<0.05), and increased survival following reperfusion to 54% (P<0.05). Monophosphoryl lipid-A also significantly reduced ischaemia severity as assessed from ST-segment elevation recorded from epicardial electrodes as well as the degree of inhomogeneity of electrical activation within the ischaemia area. There were no haemodynamic differences prior to coronary occlusion between vehicle controls and monophosphoryl lipid-A-treated dogs. These results demonstrate that monophosphoryl lipid-A reduces arrhythmia severity 24 h after administration. Although the precise mechanisms are still unclear, there is some evidence that nitric oxide and prostanoids (most likely prostacyclin) may be involved because the dual inhibition of nitric oxide synthase and cyclooxygenase enzymes by administration of aminoguanidine and meclofenamate abolished the marked antiarrhythmic protection resulted from monophosphoryl lipid-A treatment 24 h previously.
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Affiliation(s)
- A Végh
- Department of Pharmacology and Pharmacotherapy, Hungarian Academy of Sciences, Albert Szent Györgyi Medical University, Dóm tér 12, H6701, Szeged, Hungary.
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Kis A, Végh A, Papp J, Parratt J. Pacing-induced delayed protection against arrhythmias is attenuated by aminoguanidine, an inhibitor of nitric oxide synthase. Br J Pharmacol 1999; 127:1545-50. [PMID: 10455308 PMCID: PMC1566142 DOI: 10.1038/sj.bjp.0702695] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Cardiac pacing, in anaesthetized dogs, protects against ischaemia and reperfusion-induced ventricular arrhythmias when this is initiated 24 h after the pacing stimulus. Now we have examined whether this delayed cardioprotection afforded by cardiac pacing is mediated through nitric oxide. 2. Twenty-two dogs were paced (4 x 5 min periods at 220 beats min(-1)) by way of the right ventricle, 24 h prior to a 25 min period of coronary artery occlusion. Nine of these dogs were given the inhibitor of induced nitric oxide synthase, aminoguanidine (50 mg kg(-1) i.v.), 0.5 h prior to coronary artery occlusion. Sham-operated non-paced dogs with and without aminoguanidine treatment served as controls. 3. Pacing markedly (P<0. 05) reduced arrhythmia severity (ventricular fibrillation, VF, during occlusion 15%; survival from the combined ischaemia-reperfusion insult 62%) compared to control, sham-operated, unpaced dogs (VF during occlusion 58%; survival 17%). This protection was attenuated by the administration of aminoguanidine prior to coronary artery occlusion (survival from the combined ischaemia-reperfusion insult 11%, which was significantly (P<0.05) less than in the paced dogs not given aminoguanidine and similar to the controls). Aminoguanidine had no significant effects on coronary artery occlusion when given to dogs that had not been paced. In the dose used aminoguanadine transiently elevated systemic arterial pressure by a mean of 20 mmHg and reduced heart rate by a mean of 22 beats min(-1). 4. These results suggest that nitric oxide, probably derived from induced nitric oxide synthase, contributes significantly to the delayed cardioprotection afforded by cardiac pacing.
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Affiliation(s)
- Adrienn Kis
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical University, Dóm tér 12, H6701 Szeged, Hungary
| | - Agnes Végh
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical University, Dóm tér 12, H6701 Szeged, Hungary
- Author for correspondence:
| | - Julius Papp
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical University, Dóm tér 12, H6701 Szeged, Hungary
| | - James Parratt
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical University, Dóm tér 12, H6701 Szeged, Hungary
- Strathclyde Institute for Biomedical Sciences, Glasgow, U.K
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Kukushkina OI, Fedotkina LK, Balashov VP, Balykova LA, Sosunov AA. Effect of NO-synthase inhibitor L-NAME on occlusion and reperfusion arrhythmias in cats. Bull Exp Biol Med 1999. [DOI: 10.1007/bf02434938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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