The Journal of Thoracic and Cardiovascular Surgery, Vol 72, 885-891, Copyright © 1976 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Coronary vascular responses to nitroglycerin following aorta-coronary saphenous vein grafting in dogs
DG Pennington, JT LaCroix, WE Shell and MJ Williams
Phasic coronary arterial flow responses to nitroglycerin were evaluated in
15 open-chest greyhounds before and after aorta-coronary saphenous vein
grafting. Coronary flow was measured with electromagnetic probes proximal
and distal to the vein graft site. Simultaneous measurements of
branchiocephalic flow, aortic and left atrial pressure, left ventricular
pressure, and dp/dt were made. Grafts were placed during normothermic
hemodilution cardiopulmonary bypass and induced ventricular fibrillation.
Before grafting, intravenous nitroglycerin (0.6 mg.) elicited an abrupt
rise in diastolic coronary flow which decreased as aortic pressure fell and
systolic coronary flow increased. However, after grafting, nitroglycerin
elicited no change in diastolic coronary flow, whereas systolic coronary
flow increased and aortic pressure fell. In 6 control dogs treated
similarly except for aorta- coronary grafting, coronary flow responses to
nitroglycerin were unchanged. These acute experiments suggest that, in dogs
with aorta- coronary saphenous vein grafts, the coronary dilating effect of
nitroglycerin is virutally abolished.