Acute myocardial ischemia induced by LAD occlusion in dogs resulted in a loss of the early diastolic intraventricular pressure gradient and reduced ejection fraction from 56% to 37%.
Does acute myocardial ischemia alter the physiological early diastolic intraventricular pressure gradient in a canine model?
Acute myocardial ischemia significantly impairs regional systolic function and alters early diastolic intraventricular pressure gradients, supporting the role of systolic recoil in diastolic filling.
A consistent pattern of intraventricular regional pressure gradients exists under physiological conditions during the rapid filling phase of diastole in the normal dog left ventricle. We hypothesized that this pressure gradient pattern is caused, in part, by early diastolic recoil of the left ventricular walls in conjunction with release of elastic potential energy stored during systole, generating suction and thus contributing to diastolic filling. If so, any condition that interferes with normal regional systolic function might be expected to modify the pattern of the normal early diastolic intraventricular pressure gradients. Accordingly, the present study was designed to determine whether acutely induced regional systolic left ventricular mechanical dysfunction is accompanied by changes in the pattern of the early diastolic intraventricular pressure gradients. Acute myocardial ischemia was induced by balloon occlusion of the left anterior descending coronary artery (LAD) in nine anesthetized closed-chest dogs. The maximum early diastolic intraventricular pressure gradient (MIVP) was measured between the mid-left ventricle and apex with a dual-sensor micromanometer (3-cm spacing between the sensors) before and 20 minutes after LAD occlusion. Ejection fraction (EF) and number of dyskinetic chords (DChords) were measured from left ventricular contrast ventriculograms. Twenty minutes after LAD occlusion, the nine dogs evidenced significant changes in EF (56 +/- 10% to 37 +/- 8%), DChords (0 +/- 0 to 17 +/- 16 chords), left ventricular minimum pressure (-1.7 +/- 0.5 to 0.0 +/- 1.5 mm Hg), left ventricular end-diastolic pressure (4.2 +/- 1.2 to 5.9 +/- 2.2 mm Hg), and heart rate (90 +/- 17 to 103 +/- 18 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)
Courtois et al. (1990) studied Acute myocardial ischemia (n=9). Balloon occlusion of the left anterior descending coronary artery (LAD) vs. Baseline (before occlusion) was evaluated on Maximum early diastolic intraventricular pressure gradient (MIVP) and left ventricular mechanical function. Acute myocardial ischemia induced by LAD occlusion in dogs resulted in a loss of the early diastolic intraventricular pressure gradient and reduced ejection fraction from 56% to 37%.