Effects of thoracic epidural block and prenalterol on coronary vascular resistance and myocardial metabolism in patients with coronary artery disease.

A thoracic epidural block from T1 to T12 was performed with plain prilocaine in four 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 due to impairment of cardiac performance and reduction in systemic vascular resistance. The heart rate decreased moderatetly. The epidural block induced a marked reduction in coronary vascular resistance with only a moderate decrease in coronary sinus blood flow. The myocardial oxygen 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 arterial blood pressure, but did not affect the systemic or coronary vascular resistance.