Left ventricular function at rest and during supine bicycle exercise was assessed by gated radionuclide angiography in 20 diabetic patients and 18 normal control subjects without clinical evidence of heart disease. The diabetic patients were aged 21 to 44 years and all except one used insulin. No subject developed chest pain or electrocardiographic changes during exercise. Both groups had a similar rest and exercise heart rate and blood pressure, and both achieved similar work loads. The control group had an ejection fraction at rest of 65.4 +/- 6.2% (mean +/- SD) and only 1 of 18 showed a decrease with exercise; peak exercise ejection fraction averaged 77.1 +/- 7.8%. The diabetic group had a mean ejection fraction at rest of 63.7 +/- 6.5%, similar to that of the control group, but 7 of 20 showed a decrease during exercise; the exercise ejection fraction averaged 67.7 +/- 9.7%, significantly lower than that of the control group (p less than 0.01). The diabetic patients varied widely in ejection fraction response to exercise, ranging from an increase of 25% to a decrease of 21%. This response did not correlate with age, sex, duration of diabetes, smoking, retinopathy, exercise heart rate, blood pressure or rate-pressure product, work load attained or ejection fraction at rest. These data suggest that approximately one-third of patients with diabetes have subclinical left ventricular dysfunction without correlation to risk factors for atherosclerosis or other diabetic complications. Whether this is due to unrecognized coronary artery disease or primary myocardial disease remains unknown.

SUMMARY Right ventricular (RV) performance during supine bicycle exercise was evaluated by gated equilibrium nuclear angiography in 19 clinically well children with d-transposition of the great arteries (d-TGA), 6.4 ± 2.7 years after Mustard's operation. Comparisons were made between rest and peak exercise. The mean resting ejection fraction was 44 ± 12% (range 30-75%) and was unchanged at peak exercise. Eight children had a normal ejection fraction response, whereas 11 children had either no increase or a decrease in ejection fraction. Relative end-diastolic volumes decreased from resting values in all patients who had an abnormal ejection fraction response. Among patients whose ejection fraction increased, the end-diastolic volume increased in three, decreased in four and was unchanged in one at peak exercise. Heart rate increased 84% (range 52-135%) and systolic blood pressure increased 16% (range 0-28%) at peak exercise. There was no correlation between exercise response and age at surgery or interval since surgery. These data indicate that clinically well children after Mustard's procedure may have abnormal right ventricular function under stress, raising concerns about the ability of the right ventricle to function as the systemic ventricle.

SUMMARY Left ventricular function was compared in 18 normal sedentary controls (mean age 28 years, range 22-34 years) and nine endurance-trained athletes (mean age 19 years, range 15-25 years) at rest and during supine bicycle exercise. Gated radionuclide angiocardiograms were performed at rest and at each level of graded maximal supine bicycle exercise. Heart rate, blood pressure, left ventricular ejection fraction and the relative changes in left ventricular end-diastolic and end-systolic volumes were assessed. Athletes attained a much greater work load than controls (mean 22.1 kpm/kg body weight vs 13 kpm/kg body weight). Both groups achieved similar increases in heart rate, blood pressure and ejection fractions. In the controls, the mean end-diastolic volume increased to 124% of that at rest (p < 0.02) during exercise and the mean end-systolic volume decreased to 81% of the rest level (p < 0.02). In contrast, the mean end-diastolic volume did not significantly change during exercise in the athletes, and the mean end-systolic volume decreased to 64% of rest (p < 0.05). Thus, although trained and untrained healthy subjects had similar increases in the left ventricular ejection fraction during exercise, different mechanisms were used to achieve these increases. Untrained subjects increased end-diastolic volumes, whereas trained subjects decreased the end-systolic volumes. The ability of athletes to exercise without increasing preload may be an effect of training and might have important implications in reducing myocardial oxygen demand during exercise.ALTHOUGH the human left ventricular response to exercise has been the focus of many studies in the last several decades, the data on some aspects of this subject conflict. Until computer-assisted gated radionuclide cardiac angiography became available, accurate serial assessment of left ventricular volume at rest and during exercise was not technically possible.To address the question of normal left ventricular volume and ejection fraction response to exercise, we studied 18 healthy untrained subjects at rest and during supine bicycle exercise. We also studied nine endurance-trained athletes to determine whether exercise training alters the left ventricular response to exercise. Materials and Methods SubjectsThe study population consisted of 18 normal sedentary control subjects and nine endurance-trained

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In 14 subjects with severe cardiogenic shock the characteristic findings before treatment were hypotension, low cardiac output, and increased central venous pressure, with normal values for total peripheral resistance. Oliguria, lactic acidosis, hypocapnia, and hypoxemia also were present. These changes were interpreted as reflecting acute heart failure in association with a peripheral vascular response which was inadequate to maintain normal blood pressure. Isoproterenol caused a decrease in venous pressure and an increase in cardiac output. In most cases this was sufficient to increase blood pressure, despite slight reductions in peripheral vascular resistance. In a few cases, however, the inotropic effect of the drug was so small that the reduction in vascular resistance caused a further fall in arterial pressure. Metaraminol caused elevation of venous pressure, peripheral resistance, and blood pressure at the expense of some reduction of cardiac output. An approach to therapy is discussed in the light of these findings.