Effects of nitroglycerin on the major determinants of myocardial oxygen consumption

Greenberg, Henry; Dwyer, Edward M.; Jameson, A. Gregory; Pinkernell, Bruce H.

doi:10.1016/0002-9149(75)90889-9

Cited by 106 publications

(21 citation statements)

References 30 publications

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“…We arbitrarily measured echocardiographic wall thickness to the nearest 0.5 mm, approximately 6% of control enddiastolic wall thickness, while some of the techniques used in animals evidently will resolve length differences as small as 0.05 mm.2 In the present study we could detect significant differences in end-diastolic 11,[13][14][15] with nitroglycerin administration. Differences between improved systolic shortening and unimproved systolic thickening in the acute experimental preparations might be explained by speculating that the former measurements could be affected by compressive forces from surrounding normal myocardium, and the latter might not be.…”

Section: Discussionmentioning

confidence: 80%

Effects of nitroglycerin on echocardiographic measurements of left ventricular wall thickness and regional myocardial performance during acute coronary ischemia.

Komer¹,

Edalji²,

Hood³

1979

Circulation

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The effects of nitroglycerin on regional left ventricular performance, assessed by echocardiographic techniques, were investigated in anesthetized, open-chest dogs during acute myocardial ischemia. During transient occlusion of the left anterior descending coronary artery, there was end-diastolic thinning and marked reduction in systolic thickening in the central ischemic zone. Similar changes of lesser degree were noted in the border zone. The normal zone was unaffected. Infusion of nitroglycerin during ischemia in dosages of 2.5--50 microgram/kg/min reduced left ventricular end-diastolic pressure without changing the abnormalities of systolic wall thickening. Effects of bolus injections of 20 and 50 microgram/kg of nitroglycerin were similar, although this also lowered aortic pressure. In a subgroup of animals in which nitroglycerin infusion was unaccompanied by tachycardia, there was also no evidence that ischemic dysfunction was altered. We conclude that nitroglycerin does not improve regional myocardial performance in acutely ischemic canine myocardium. The decrease in preload is probably entirely due to the peripheral effects of the agent.

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Section: Discussionmentioning

confidence: 80%

Effects of nitroglycerin on echocardiographic measurements of left ventricular wall thickness and regional myocardial performance during acute coronary ischemia.

Komer¹,

Edalji²,

Hood³

1979

Circulation

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“…The anesthetized and openchest dog cannot provide results that can be applied directly to patients suffering acute infarction. However, Epstein (1973) and others (Greenberg et al, 1975;Banka et al, 1975) have shown that nitroglycerine and nitroprusside can exert beneficial and deleterious effects on acute regional myocardial ischemia. It seems necessary to consider the relationship between dose and effects on pathophysiology when making interventions to salvage ischemic myocardium.…”

Section: Discussionmentioning

confidence: 99%

The effects of nifedipine on acute experimental myocardial ischemia and infarction in dogs.

Selwyn¹,

Welman²,

Fox³

et al. 1979

Circulation Research

111

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SUMMARY We studied 25 anesthetized and thoracotamized dogs before and during 5 hours of acute regional myocardial ischemia. Krypton-81m ( 8Xm Kr) was infused constantly into the aortic sinuses. The myocardial equilibrium of this tracer was used to image and assess the distribution of regional myocardial perfusion using a gamma camera and digital computer. The epicardial ECG was recorded, S-T segment elevation and the loss of R and appearance of Q waves were measured, and the plasma activity of creatine kinase (CK) was determined in aortic and coronary venous blood throughout these experiments. Ten dogs underwent left anterior descending coronary artery (LAD) narrowing for 5 hours and received no drugs. Five dogs received nifedipine 13 fig/kg, and another five received 1.0 /ig/kg intravenously 30 minutes after LAD narrowing. Those dogs receiving nifedipine, 13 fig/kg, showed a 30% fall in aortic pressure, a 12% rise in heart rate, and an extension of regional ischemia. The ECG showed an extension of infarct size, and CK release into the coronary vein appeared earlier than in the controls. Dogs receiving nifedipine, 1 /ig/kg, showed a 12% fall in blood pressure, no rise in heart rate, an improvement in regional perfusion, and ECG signs that suggested limitation of infarct size. There also was delayed release of coronary venous CK. The effects of nifedipine on the natural history of regional myocardial perfusion, the electrocardiogram, and enzyme release from the heart were dose related and cannot be generalized. These observations warrant further clinical investigation to improve the use of this agent in man. Circ Res 44: 16-23, 1979 THE extent of ischemic myocardial damage during acute myocardial infarction is one of the important determinants of morbidity and mortality. Recent studies have encouraged a search for interventions that can affect the balance between energy supply and demand during acute infarction of the heart (Maroko et al., 1971; Braunwald andMaroko, 1974). Nifedipine (4-(2'-nitrophenyl)-2,6-dimethyl-l,4-dihydropyridine-3,5-dicarboxylic acid dimethyl ester) has been shown to retard the transmembrane influx of calcium into ischemic myocardial cells, increase coronary blood flow, delay ischemic contracture, and preserve myocardial creatine kinase activity (Henry, 1975;Fleckenstein, 1975;Vater, 1975;Schmier et al., 1975). These combined pharmacological properties suggest that a favorable effect on acutely ischemic myocardium may be possible.The purpose of this study was to observe the changes of regional myocardial perfusion, the epicardial ECG, and the appearance of creatine kinase activity in coronary venous blood in dogs during the 5 hours following occlusion of the left anterior descending coronary artery (LAD). The dose-related effects of nifedipine on these parameters were measured, and the use of this drug to protect the ischemic myocardium is discussed. MethodsTwenty-five mongrel dogs weighing 30-55 kg were anesthetized with intravenous sodium thiopental (Pentothal, 12 mg/kg). Respiration ...

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“…This event, to gether with the adrenergic-mediated increase in oxygen consumption, leads to a self-main taining worsening of ischemia. Nitroglycerin improves ventricular function by reducing preload and outflow impedance [15][16][17][18], hence increasing diastolic perfusion time, and, therefore, it seems capable of interrupt ing this deleterious vicious cycle.…”

Section: Discussionmentioning

confidence: 99%

Electromechanical Events during Spontaneous Angina

et al. 1988

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The electromechanical events occurring during acute myocardial ischemia were assessed in 10 patients who developed spontaneous angina during cardiac catheterization. Aortic pressure and electrocardiogram were recorded, and heart rate and systolic and diastolic time intervals were measured under control conditions, at the onset of angina and during the relief of chest pain. In 5 patients spontaneous angina was accompanied by an increase in heart rate and systemic arterial pressure and by ST segment changes in anterior or anterolateral precordial leads. Diastolic time, expressed as percent of cardiac cycle, shortened from 48.8 ± 3.6% at rest to 33.6 ± 4.8% (p < 0.01) at the onset of angina, as a consequence of a significant increase in both electromechanical systole and heart rate, and returned to control values within 10 min after sublingual nitroglycerin. In the remaining 5 patients, spontaneous angina was accompanied by a decrease in heart rate and systemic arterial pressure and by ST segment changes in the inferior or inferolateral leads. The diastolic time increased significantly (p < 0.05) from 39.4 ± 6.1 % at rest to 47.8 ± 9% at the onset of angina, as a consequence of a significant decrease in heart rate and a slight decrease in electromechanical systole. Since coronary perfusion takes place mainly during diastole, our results suggest that the reflex increase in adrenergic tone may worsen myocardial ischemia by affecting diastolic perfusion time. In contrast, the increase in vagal tone may contribute to spontaneous relief of angina by prolonging diastolic perfusion time.

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Effects of nitroglycerin on the major determinants of myocardial oxygen consumption

Cited by 106 publications

References 30 publications

Effects of nitroglycerin on echocardiographic measurements of left ventricular wall thickness and regional myocardial performance during acute coronary ischemia.

Effects of nitroglycerin on echocardiographic measurements of left ventricular wall thickness and regional myocardial performance during acute coronary ischemia.

The effects of nifedipine on acute experimental myocardial ischemia and infarction in dogs.

Electromechanical Events during Spontaneous Angina

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