Effects of Thoracic Epidural Block and Prenalterol on Coronary Vascular Resistance and Myocardial Metabolism in Patients with Coronary Artery Disease

Abstract

A thoracic epidural block from T1 to T12 was performed with plain prilocaine in 4 patients with coronary artery disease who were scheduled for abdominal aortic aneurysm surgery. The hemodynamic effects of the block consisted of marked reduction in arterial blood pressure [ABP] due to impairment of cardiac performance and reduction in systemic vascular resistance [VR]. The heart rate decreased moderately. The epidural block induced a marked reduction in coronary VR with only a moderate decrease in coronary sinus blood flow. The myocardial O2 and lactate utilization decreased in parallel to the decrease in cardiac work. In spite of the absence of arrhythmias and ST-T segment changes following the epidural block, regional myocardial dysoxia could not be ruled out with the present methods. Administration of the cardioselective .beta.1-adrenoreceptor agonist prenalterol increased cardiac performance and thereby ABP, but did not affect the systemic or coronary VR.