Reversible Cardiac Failure During Angina Pectoris

Left ventricular end-diastolic pressure and left ventricular stroke work were measured during a 10-min period of atrial pacing in 10 normal subjects and 30 patients with coronary artery disease. The normal subjects and the patients with coronary artery disease who did not experience angina during pacing reacted similarly with a fall in left ventricular end-diastolic pressure from 8 to 2 mm Hg returning to control values on cessation of pacing. The average left ventricular end-diastolic pressure during pacing in the 21 patients who developed angina was similar to control values although this pressure rose to abnormal levels in four patients. On cessation of pacing the left ventricular end-diastolic pressure rose abruptly to an average value of 22 mm Hg. This lack of elevation of filling pressure during pacing and the rise to abnormal levels on termination of pacing can best be explained by relating left ventricular end-diastolic pressure to left ventricular stroke work. Analyzed in this fashion it is evident that the ischemic ventricle is operating on a depressed ventricle function curve. This depression of function is reversible following cessation of pacing and can be prevented by the prior administration of nitroglycerin.