READERS

COMMENTS

Left Ventricular Diastolic Volume Changes by Exercise Radionuclide Ventriculography in Normal Subjects and in Patients with Coronary Arterial Narrowing Choi et al’ have suggested in a recently published study of exercise radionuclide ventriculography in patients with suspected coronary artery disease that left ventricular end-diastolic volume may increase in normal subjects during supine exercise. We2 previously evaluated the response of end-diastolic volume changes with upright and supine exercise in both patients with normal coronary arteries and normal left ventricular function and in patients with coronary artery disease with or without myocardial infarction. Our findings, using the same technique as that of Choi et al, demonstrated no changes in systolic volume in the supine position during maximal exercise compared with rest. However, there was a 20% increase in left ventricular diastolic volume during exercise in the normal subjects studied by Choi et al. This discrepancy in findings may be due to the definition of normal subjects. In our study, the patients who were deemed “normal” had no coronary stenoses 150% and had normal left ventricular function at rest. They were able to exercise to a maximal heart rate of 155 f 16 beats/ min and a systolic blood pressure of 194 & 26 mm Hg. The level of exercise was significantly higher than that instituted for the normal subjects of Choi et al, who were only able to exercise to a maximal heart rate of 118 f 28 beats/min and a systolic blood pressure of 159 f 29 mm Hg. This lower level of exercise in these “normal” subjects may be due to coronary atherosclerosis with stenoses -