Compensatory cardiac mechanisms evoked by acute occlusion of the right coronary artery in dogs.
The cardiac response to intermittent occlusion of the right coronary artery was examined in anesthetized open-chest dogs at different levels of blood volume. The reduction in stroke volume averaged 15 +/- 2% and was related to the extent of the ischemic area (r = 0.72), which comprised 45-70% of the free wall of the right ventricle. Ultrasonic recordings of segment lengths showed end-diastolic distention and activation of the Frank-Starling mechanism in the uninjured parts of the free wall. The transseptal end-diastolic pressure difference was abolished, suggesting movement of the interventricular septum to the left. Nevertheless, the relationship between stroke volume and left ventricular end-diastolic pressure (left ventricular function curve) as well as the relationship between stroke volume and the end-diastolic segment length of the left ventricular free wall were unaltered. Comparisons of data obtained at similar stroke volume showed activation of the Frank-Starling mechanism in the interventricular septum which may compensate for the negative effect of a change in its position.
D000818:Animals; D001794:Blood Pressure; D001810:Blood Volume; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000502:physiology*; D004285:Dogs; D004452:Echocardiography; D005260:Female; D006439:Hemodynamics; D007511:Ischemia / Q000503:physiopathology; D008297:Male; D009200:Myocardial Contraction; D013318:Stroke Volume; D016276:Ventricular Function