Myocardial and cerebral hemodynamics during tachyarrhythmia-induced hypotension in the rat

Abstract

Background: The different vulnerabilities of heart and brain to hypotension and hypoxia have been discussed. Hemorrhagic or cardiogenic hypotension appears to cause greater cerebral lesions than drug-induced hypotension. The present model was established to evaluate myocardial blood flow (MBF) and function of the heart and cerebral blood flow (CBF) during tachyarrhythmias and to characterize the capacity of blood flow regulation in the heart and brain during tachycardia-induced borderline hypotension. Methods and Results: MBF and CBF were determined with radiolabeled microspheres. Coronary and central venous oxygen tensions were measured to estimate myocardial and cerebral oxygen consumption (MVo2 and CVo2). Measurements were performed in 62 Sprague-Dawley rats during sinus rhythm and high-rate left ventricular pacing and after hemorrhage. In control rats, MBF and CBF were 5.08±1.07 and 1.09±0.29 mL · g-1 · min-1. MBF increased (7.21±1.98 mL · g-1 · min-1, P