Beta-adrenergic blockade during severe ischemia

Abstract

Objective: To examine the effect of acebutolol, a beta-adrenergic-receptor blocker, on severe regional myocardial ischemia, specifically the effects on regional myocardial function and metabolism.

Design: Randomized study.

Setting: Animal laboratory of the Department of Anesthesiology and Critical Care, University of Stellenbosch Medical School.

Participants: Anesthetized open-chest pig model (n = 18).

Interventions: Regional left ventricular function and metabolism were evaluated. Severe stenosis was applied to the left anterior descending coronary artery. After establishing regional myocardial ischemia, acebutolol was administered intravenously, and results were compared with controls who did not receive acebutolol. Animals were prospectively randomized to 1 of the groups.

Measurements and main results: Regional myocardial function and metabolism were assessed by end-systolic pressure relationship, regional systolic shortening, postsystolic shortening, regional myocardial oxygen consumption, and lactate dynamics. Coronary blood flow was determined with a Doppler flow probe. Results indicated that acebutolol increased regional myocardial blood flow, and this resulted in less severe regional myocardial ischemia, improved function, and an increase in regional myocardial oxygen consumption.

Conclusion: The beta-Adrenergic-receptor antagonist was successful in reducing regional myocardial ischemia in this model. This reduction was achieved by an increase in coronary blood flow, which resulted in an improvement in regional mechanical function and an increase in oxygen consumption.