To determine the changes in left ventricular volume and their time course during exercise we studied 30 runners. Left ventricular end-diastolic and end-systolic volumes were measured from biapical two-dimensional echocardiograms recorded during graded upright bicycle exercise. The validity of this echocardiographic technique was assessed by comparing measurements at rest and exercise with results obtained by gated equilibrium radionuclide angiography in 10 patients with coronary artery disease. Although the absolute volume measurements were lower by echocardiography, ejection fraction was not significantly different and the directional changes in volume during exercise were comparable. In the runners, resting left ventricular end-diastolic volume measurements by echocardiography correlated with their maximum bicycle exercise endurance times (r = .80). Left ventricular end-diastolic volume, stroke volume, and ejection fraction increased during exercise with the most marked changes occurring in the first half of exercise. Systolic blood pressure/end-systolic volume (SBP/ESV) also increased during exercise, but the largest change occurred during the second half of exercise. Left ventricular volumes were larger in the 12 competitive marathon runners (maximum exercise duration -27 min) as compared with the 18 noncompetitive runners (exercise duration < 23 min): resting end-diastolic volume 130 ± 29 (SD) ml vs 87 ± 20 ml (p < .001), respectively. During exercise the competitive runners exhibited a larger increase in end-diastolic volume and the noncompetitive athletes showed a greater increase in SBP/ESV. Therefore, highly trained competitive marathon runners make greater use of the less energy-consuming Frank-Starling mechanism to accomplish high levels of isotonic exercise performance as compared with less well-trained runners. Circulation 72, No. 6, 1237No. 6, -1243No. 6, , 1985 LONG-TERM isotonic exercise training results in a reduction in resting heart rate and an increase in left ventricular end-diastolic volume.`' Also, isotonically trained individuals are able to achieve higher values for stroke volume, cardiac output, and exercise workload as compared with untrained individuals, despite similar values for peak exercise heart rate, blood pressure, and ejection phase indexes of left ventricular performance.5' 6 However, it is unclear whether the increased left ventricular output during exercise in athletes is related simply to the larger resting end-diastolic volume that persists during exercise, or whether further

The effects of oral diltiazem (360 mg/day) on exercise tolerance, left ventricular performance, and plasma lactate and catecholamine levels were studied in 13 patients with atherosclerotic coronary artery disease in a placebo-controlled, randomized, double-blind protocol. Exercise duration to the onset of ischemic ST segment depression, time to angina pectoris, and time to peak exercise improved by 120, 174, and 144 sec, respectively (p < .0001). Left ventricular ejection fraction, as determined by radionuclide angiography, increased in patients at rest from 52 + 11% (mean + SD) during placebo therapy to 58 11% during diltiazem therapy (p < .001); at peak exercise ejection fraction increased from 44 11% during placebo treatment to 52 + 15% during diltiazem therapy (p < .01). The mean plasma norepinephrine level in patients at rest increased from 498 + 221 pg/ml during placebo treatment to 667 + 272 pg/ml during diltiazem therapy (p < .05).Resting standing blood pressure and supine and standing diastolic blood pressures decreased significantly with diltiazem. In all 10 patients followed over a long term, oral diltiazem caused persistent improvement in exercise performance at 12 to 20 weeks, without evidence of placebo effects. Thus, diltiazem is highly effective in divided doses of 360 mg/day for the therapy of chronic angina pectoris due to coronary artery disease.Circulation 68, No. 1, 139-147, 1983. DILTIAZEM HYDROCHLORIDE has been shown to be effective in the treatment of exertional angina pectoris in doses of 240 mg/day.

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