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Query: UMLS:C0151744 (myocardial ischemia)
 31,282 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The coronary collateral circulation of goat is very spare, so myocardiac ischemia model of goat can simulate the patient previously with normal coronary circulation and suddenly developing complete occlusion of coronary arteries. In this study 80 Chengdu goats were used, and the branches of their left coronary artery were ligated. Ventricular tachycardia (VT) developed in 23 goats and ventricular fibrillation (VF) in 39 goats. VT and VF both occurred in the early phase of acute myocardial ischemia, and both had 6 min as the median time of onset. In 71 cases data on the weight of myocardiac ischemic area were collected, in which the weight percentage of ischemic area relating to the ventricles of 34 goats with VF was significantly higher than that of 37 goats without VF (35.4 +/- 2.4% vs 19.5 +/- 1.9%). After coronary ligation, 9 cases directly precipitated into VF which could not be defibrillated. In the remaining 62 cases, the weight percentage of ischemic area of 21 cases with VT was higher than that of 41 cases without VT (32.9 +/- 2.8% vs 20.9 +/- 2.1%). The relationships between the incidence of VT or VF and the weight percentage of ischemic area were fitted with logistic curve. The likelihood of occurrence of VT or VF is increased as the weight percentage of ischemia area goes up.
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PMID:[Relation between the occurrence of malignant arrhythmia during acute myocardial ischemia and the weight of ischemic myocardium in goats]. 129 21

Isolated perfused rat heart model was used to observe the protective effects of berbamine on myocardial ischemia/reperfusion injury. The hearts were significantly injured by 40 min global ischemia followed by 20 min reperfusion. Berbamine could significantly improve heart function, prevent ventricular fibrillation, reduce CK release, preserve Na,K-ATPase activity, and reduce Na+ gain and K+ loss during ischemia and Ca2+ overload during reperfusion. With the use of low temperature ESR technique, in hearts subjected to 40 min ischemia and 15 sec reperfusion, oxygen-centered free radical signals became much more intense. In the presence of berbamine, these signals decreased. Results showed that berbamine could alleviate myocardial ischemia/reperfusion injury. This effect might be due to: 1) preserved myocardial Na,K-ATPase activity and inhibition of sodium overload at the end of ischemia, which might further lead to attenuation of reperfusion-induced calcium overload, and 2) reduction of oxygen free radical generation during reperfusion.
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PMID:Mechanisms of protective effects of berbamine on ischemia/reperfusion injury in isolated rat heart. 133 20

Bucindolol is a new beta blocker with marked vasodilatory properties and intrinsic sympathomimetic activity. We tested its potential effect against ventricular fibrillation (VF), in a pig model of acute myocardial ischemia. Bucindolol 6 mg/kg IV was administered in two equally divided doses, the first 30 minutes prior to, and the second 10 minutes after, ligation of the anterior descending coronary artery (CAL) in anesthetized open-chest pigs. Bucindolol decreased the incidence of VF to 1/11 versus 14/16 in the control group (p less than 0.005). Bucindolol also decreased the duration of ventricular tachycardia, 15 +/- 8 seconds versus 104 +/- 32 seconds in the control group (p less than 0.01). Bucindolol maintained LVmaxdP/dt at predrug and pre-CAL values, whereas LVmaxdP/dt was decreased by CAL in the control group. Bucindolol decreased arterial pressure and heart rate. Bucindolol increased blood flow in the peripheral ischemic zone (24.6 +/- 1.8% versus 16.2 +/- 1.7% (percent of pre-CAL value) in controls, p less than 0.002), as well as in the nonischemic zones (periischemic zone: 126.4 +/- 6.1% versus 96.7 +/- 4.8% in the control group, p less than 0.0005; remote nonischemic zone: 126.6 +/- 7.1% versus 87.1 +/- 4.3% of pre-CAL value in the control group, p less than 0.0001). Bucindolol had marked antiarrhythmic effects that were associated with beneficial effects on the mechanical function of the left ventricle and on blood flow to the ischemic myocardium.
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PMID:Bucindolol, a beta blocker, decreased ventricular fibrillation and maintained mechanical function in a pig model of acute myocardial ischemia. 135 66

To determine the incidence and characteristics of ventricular dysrhythmias (premature ventricular contractions greater than 30/min, ventricular tachycardia greater than or equal to 3 beats, and ventricular fibrillation) and whether a relationship exists between ventricular tachycardia and myocardial ischemia in patients undergoing coronary artery bypass graft surgery, we continuously monitored 50 patients for 10 perioperative days using two-lead electrocardiography. Electrocardiographic changes consistent with ischemia were defined as a reversible ST depression greater than or equal to 1.0 mm, or ST elevation greater than or equal to 2.0 mm from baseline, lasting at least 1 minute. Ventricular dysrhythmias developed in 10% of patients preoperatively and in 16% intraoperatively before bypass surgery. The highest incidence occurred postoperatively, with ventricular dysrhythmias developing in 66% of patients (22% to 44% of patients on any postoperative day 0 to 7). Premature ventricular contractions were greater than 30/hr in 6% of patients preoperatively, in 8% intraoperatively before bypass, and in 34% postoperatively (6% to 23% of patients on any postoperative day). Twenty-nine patients (58%) developed 76 verified episodes of greater than or equal to 3 beats of ventricular tachycardia. Ventricular tachycardia occurred in 6% of patients preoperatively (four episodes), in 8% of patients intraoperatively prior to bypass (four episodes), and 54% of patients postoperatively (5% to 21% on any postoperative day). No patient developed ventricular fibrillation. All postoperative ventricular tachycardia episodes (after tracheal extubation) were asymptomatic. Postoperatively, 48% of patients developed ischemia, compared with 12% preoperatively and 10% intraoperatively before bypass surgery. Only 5 of 68 (7%) postoperative ventricular tachycardia episodes occurred within 3 hours of an ischemia episode.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ventricular dysrhythmias in patients undergoing coronary artery bypass graft surgery: incidence, characteristics, and prognostic importance. Study of Perioperative Ischemia (SPI) Research Group. 137 Mar 63

Myocardial ischemia followed by reperfusion was produced in artificially respirated, open-chest rats. Coronary artery ligation for 6 min rarely evoked arrhythmias; however, reperfusion after this period rapidly produced severe dysrhythmias in all control animals. Reperfusion after 12 min of ischemia produced less frequent dysrhythmias than after coronary occlusion for 6 min. Feeding of a linoleic acid-rich diet, applying 12% sunflower seed oil in rat food pellet for 4 weeks, decreased the incidence of reperfusion-induced ventricular fibrillation both after 6 min (2/15 vs. 7/11) and 12 min (0/11 vs. 2/8) of myocardial ischemia and the incidence of other arrhythmias was also decreased. The number of animals developing no arrhythmias during reperfusion was increased (8/15 after 6 min of ischemia, 4/11 after 12 min of ischemia vs. 0/11 and 0/8 in controls, respectively). Our results indicate that increased dietary consumption of linoleic acid decreased the occurrence of life-threatening arrhythmias both during the acute phase of myocardial ischemia and during reperfusion in anesthetized rats.
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PMID:Effect of dietary sunflower seed oil on the severity of reperfusion-induced arrhythmias in anesthetized rats. 137 86

The potential antiarrhythmic efficacy of pharmacologic parasympathetic activation is still controversial. This study assessed the antiarrhythmic effect of saline solution (n = 9) and of the muscarinic agonist oxotremorine (1.5 micrograms/kg administered intravenously) (n = 17) in a feline animal model in which malignant arrhythmias were reproducibly elicited by the combination of acute myocardial ischemia and left stellate ganglion stimulation. Although saline solution had no effect, oxotremorine significantly decreased heart rate, blood pressure, the incidence of ventricular fibrillation from 47% to 0% (p = 0.004), and the incidence of malignant arrhythmias (either ventricular tachycardia or ventricular fibrillation) from 88% to 12% (p less than 0.001). When reduction in heart rate was prevented by means of atrial pacing (n = 15), the incidence of malignant arrhythmias was still significantly reduced from 87% to 27% (p = 0.001). Arrhythmias were also graded as follows: 0 = no premature ventricular contractions; 1 = 1 to 10 premature ventricular contractions; 2 = 11 to 50 premature ventricular contractions; 3 = ventricular tachycardia; 4 = ventricular fibrillation. Arrhythmia severity was 3.29 +/- 0.16 (SEM) in the control trials and was reduced to 0.76 +/- 0.26 (p less than 0.001) by oxotremorine and to 1.53 +/- 0.34 by oxotremorine and pacing (p = 0.002). Therefore a muscarinic agonist can significantly reduce malignant arrhythmias during acute myocardial ischemia and may represent a novel approach to the prevention of sudden cardiac death.
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PMID:Prevention of life-threatening arrhythmias by pharmacologic stimulation of the muscarinic receptors with oxotremorine. 138 85

Adaptation of rats to cold and physical exercise prevented ventricular fibrillation (VF) caused by the occlusion of the left anterior coronary artery. In the heart of adapted rats with acute myocardial ischemia, myocardial enkephalins increased whereas the level of cAMP declined as compared to nonadapted animals. Injection of dalargin before the occlusion of the coronary artery in rats prevented both VF and a decrease of VF threshold. The peptide averted the rise of cAMP content in the heart during acute myocardial ischemia. The data obtained suggest that the rise of endogenous myocardial enkephalins may have an important role in antiarrhythmic action of adaptation. It is assumed that antiarrhythmic effect of enkephalins may be related to the restriction of sympathetic influence on the heart.
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PMID:[Role of enkephalins in the mechanism of anti-arrhythmia effects of adaptation in acute myocardial ischemia]. 138 59

Remarkable progress has been made both experimentally and clinically in defining the influence of behavioral states on susceptibility to life-threatening arrhythmias. Biological models have been developed to emulate anger and fear and have permitted detailed study of the intermediary mechanisms involved in stress-induced ischemia and ventricular fibrillation. The studies highlight the importance of adrenergic factors and the pathological significance of the poststress state. Clinically, the role of daily stresses in inducing silent myocardial ischemia and arrhythmias has been extensively characterized, and standardized behavioral stress tests have become available. Certain sleep states have been found to provoke ischemic episodes and arrhythmias. In particular, phasic rapid eye movement (REM) sleep has been shown both in animals and humans to conduce to perfusion abnormalities and propensity to fibrillation. Episodic surges in sympathetic nervous system activity appear to be the underlying basis. These conceptual and practical advances illustrate the promise of behavioral cardiology in the diagnosis and treatment of individuals at risk for sudden cardiac death.
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PMID:Behavioral states and sudden cardiac death. 138 2

Congestive heart failure (CHF) is a common manifestation of hypertension, coronary artery disease, and dilated cardiomyopathy. The Framingham study showed that the incidence of CHF increases twofold with each decade of age. The presence of CHF increases the age-adjusted death rate 5.5-fold for women and 8-fold for men, and it increases the sudden death rate 5.5-fold in both men and women. Ventricular arrhythmias are a common accompaniment of CHF. Ambient ventricular premature complexes occur in most of these patients, and nearly one half of all CHF patients will have nonsustained ventricular tachycardia on a 24-h ambulatory electrocardiographic (Holter) recording. In addition, low left ventricular ejection fraction (LVEF) predicts inducible sustained ventricular tachycardia on electrophysiologic study. One-year mortality increases with worsening New York Heart Association (NYHA) Functional Class and decreasing LVEF. As the overall yearly mortality increases, the proportion of patients who die of arrhythmias decreases. The precise mechanism of death is frequently difficult to assess. Nonarrhythmic causes of death include CHF, shock, electromechanical dissociation, and myocardial rupture. Arrhythmic causes are most commonly due to ventricular tachycardia/ventricular fibrillation. Bradycardic events (asystole or heart block) are usually associated with progressively worsening CHF. Noncardiac causes that may confuse classification include pulmonary embolus and cerebrovascular accident. Because many patients have ischemic heart disease as the etiology of the CHF, a recurrent ischemic event can likewise make classification difficult. Overall, approximately one half of all deaths in CHF are arrhythmic and one half are nonarrhythmic.
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PMID:Clinical significance and management of arrhythmias in the heart failure patient. 139 10

In a retrospective study of 520 patients with in-hospital ventricular fibrillation 421 (81%) had acute myocardial infarction (MI), 66 (13%) had ischaemic heart disease (IHD) without MI, 33 (6%) had no signs of IHD. The in-hospital mortality of these three groups was 51%, 52%, and 27%, respectively (P = 0.01). Logistic regression analysis demonstrated that heart failure and cardiogenic shock were significant risk factors for in-hospital death among patients with IHD. Among discharged patients 1 and 5 years survival was 78% and 51% for patients with MI, 63% and 25% for patients with IHD, 67% and 54% for patients without IHD. A proportional hazard model demonstrated old age, heart failure and cardiogenic shock as risk factors for long-term prognosis, while MI was associated with a reduced relative risk ratio = 0.58 of long-term mortality among patients with IHD. In conclusion, patients with known IHD suffering in-hospital VF without AMI have a very poor short- and long-term prognosis. These patients need extensive cardiac examination.
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PMID:Prognosis of ventricular fibrillation in hospital. 139 27


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