Mechanical Increase of Vascular Resistance in Experimental Myocardial Infarction with Shock

Abstract

The hemodynamic and cardiac metabolic effects of increasing central aortic pressure by obstructing the abdominal aorta with a balloon catheter introduced via a femoral artery were determined in 28 anesthetized dogs with acute myocardial infarction and shock produced by coronary embolization with plastic spheres. Following coronary embolization, aortic pressure, cardiac output, and left ventricular mechanical efficiency declined in all animals; left ventricular "excess lactate" appeared in about one-half. With abdominal aortic obstruction for 1 hour, there were significant elevations of postembolic aortic pressure, coronary flow, cardiac output, left ventricular oxygen consumption and mechanical efficiency. Left atrial pressure rose slightly but not beyond normal limits. Arterial-coronary sinus oxygen difference diminished, and left ventricular excess lactate diminished or disappeared in 60% of the animals in which it was noted in the postembolic state. After 1 hour of abdominal aortic obstruction, cardiac output, central aortic pressure, and coronary flow diminished moderately. It is concluded that mechanical increase of vascular resistance for periods up to 1 hour may improve myocardial performance in acute myocardial infarction with shock. The increased left ventricular oxygen needs are met adequately by the increase of coronary flow associated with the increase of perfusion pressure. ADDITIONAL KEY WORDS coronary flow myocardial metabolism cardiac output myocardial lactate dogs circulatory support aortic pressure by guest on June 15, 2015 http://circres.ahajournals.org/ Downloaded from </ > c .JO JO m v> H Z o m -X "O m 70 m Z 2 o 70 Z > JO q o Mean values with standard error in parentheses. •Change from postembolic level obtained prior to balloon inflation: P < 0.05. fMean weight = 23.1 (±1.1) kg. 00 by guest on June 15, 2015

Intraoperative bypass graft flow in intra-aortic balloon pump–supported patients: Differences in arterial and venous sequential conduits

“…Under hypoxic conditions, myocardial performance depends on flow in the coronary arteries and/or bypass grafts. 16,17 During cardiogenic shock, isolated reduction of afterload does not significantly improve myocardial function-enhanced coronary driving pressure, and therefore perfusion, are necessary to reverse ventricular failure. 16,17 Further, treatment with inotropes and vasodilators (and inodilators) increase left ventricular work without increasing myocardial perfusion and actually reduce coronary flow by decreasing diastolic perfusion pressures.…”

“…16,17 During cardiogenic shock, isolated reduction of afterload does not significantly improve myocardial function-enhanced coronary driving pressure, and therefore perfusion, are necessary to reverse ventricular failure. 16,17 Further, treatment with inotropes and vasodilators (and inodilators) increase left ventricular work without increasing myocardial perfusion and actually reduce coronary flow by decreasing diastolic perfusion pressures. 16,18 Again, our observational study showed significant increases in mean diastolic and mean blood flow in bypass grafts--without increases in mean systolic flowdespite concomitant reductions in systemic diastolic arterial pressure (afterload reduction) induced by IABP.…”

Hemodynamics, coronary blood flow, and myocardial metabolism in coronary shock; response to l-norepinephrine and isoproterenol

“…The relationship shown in Fig. 3 Hemodynamics, CBF, and Myocardial Metabolism in Coronary Shock coronary embolization by rising aortic coronary perfusion pressure (60,84).…”

Influence of Changes in Heart Rate, Aortic Pressure and Flow Rate upon Experimental Coronary Insufficiency

“…Vii.lagrana et al [15] found that, after coronary ligation, constriction of the ascending aorta augmented coronary blood flow and reduced the area of myo cardial infarction. Kuhn et al [6] demonstrated that in the dog with acute myocardial infarction and shock, an increase of coronary perfusion pressure produced by obstructing the abdominal aorta was associated with an increase of coronary blood flow, cardiac output and mechanical effi ciency of the left ventricle. Our results are not inconsistent with these findings.…”