How does increased peripheral resistance via specific arterial constrictions affect left ventricular hemodynamics in anesthetized dogs?
The cardiac response to increased peripheral resistance varies by the site of arterial constriction, with brachiocephalic constriction uniquely enhancing stroke work and peak power likely due to reflex and humoral inotropic mechanisms.
Changes in the resistance to left ventricular outflow were produced in the anesthetized, open-chest dog by constriction of the descending thoracic aorta, the brachiocephalic artery, or a combination of the two. With constriction of the brachiocephalic artery alone, left ventricular stroke work and peak power were considerably enhanced, left atrial pressure increased insignificantly, and cardiac output remained constant. With aortic or combined constriction, cardiac output diminished and left atrial pressure rose, but peak power and stroke work did not change significantly. The enhancement of peak power and stroke work by brachiocephalic constriction may be ascribed in part to the supervention of reflex and humoral inotropic mechanisms.
Mattos et al. (1963) studied this question.