Correlation of maximum aortic and carotid flow acceleration in chronically instrumented dogs.

Peak flow acceleration measured in the common carotid artery was compared with peak flow acceleration measured in the ascending aorta of five chronically instrumented dogs. Electromagnetic flow sensors, myocardial electrocardiographic leads, right atrial catheters, and coronary occluders were implanted through an incision of the chest at the fourth intercostal space and a ventral midline incision of the neck under sterile conditions while the dogs were anesthetized with sodium pentoharbital. Experiments began 10 days after surgery. We investigated the response to exercise, to 60-second occlusions of the circumflex branch, the anterior descending branch, or both branches of the left coronary artery, to induction of short-acting barbiturate anesthesia, and to intravenous infusion of three concentrations each of isoproterenol (0.8, 1.5-3.0, and 4.0 fig/min), lnorepinephrine (0.8, 2.0, and 4.0 /xg/min), and acetylcholine (0.3-0.5, 0.8-2.0, and 4.0 mg/ min). During coronary occlusion, exercise, and induction of anesthesia, both accelerations changed in the same direction and approximately to the same extent. During isoproterenol infusion, both accelerations increased, but the maximum carotid flow acceleration increased more than did the maximum aortic flow acceleration. When lnorepinephrine was infused, the changes were small and were not always in the same direction. When acetylcholine was infused, peak carotid flow acceleration decreased. Peak carotid flow acceleration might be useful as an indirect measure of myocardial mechanical performance during coronary occlusion, anesthesia, and exercise, except during potent peripheral vasodilation like that caused by acetylcholine.