Author + information
- Received April 15, 1986
- Revision received October 1, 1986
- Accepted October 10, 1986
- Published online April 1, 1987.
- ↵1Address for reprints: Steven D. Colan, MD, Department of Cardiology, The Children's Hospital, 300 Longwood Avenue, Boston, Massachusetts 02115.
Physiologic hypertrophy resulting from intense athletic participation has been reported to result in normal, reduced and augmented overall left ventricular performance. Rather than representing true differences in left ventricular contractility, these data may reflect the variable degree of ventricular dilation and increased wall thickness that occur with different types of exercise. As such, the resultant altered loading conditions may diminish the ability of the usual indexes of left ventricular function to accurately assess the left ventricular contractile state. Therefore, three groups of elite athletes with distinct patterns of myocardial hypertrophy were investigated utilizing recently developed load-independent contractility indexes. Age-matched control subjects (n = 33) were compared with 11 swimmers, 11 longdistance runners and 11 power lifters. Rest echocardiogram, phonocardiogram and calibrated carotid pulse tracing were used to calculate left ventricular dimensions, wall thickness, mass, fractional shortening, velocity of shortening and mean, peak and end-systolic wall stresses and the stress-time and minute stress-time integrals.
Compared with control subjects, all athletes had increased left ventricular mass, even when values were normalized for body surface area. Runners had a dilated left ventricle and normal wall thickness, swimmers had a mildly dilated ventricle with increased wall thickness and power lifters had normal cavity size with markedly increased wall thickness. Peak systolic wall stress was normal in runners and swimmers and reduced in power lifters, whereas end-systolic stress was low in swimmers and power lifters and normal in runners. The minute stress-time integral, a measure of myocardial oxygen consumption, was normal in runners and swimmers but was significantly reduced in lifters. In runners, fractional shortening was significantly reduced with normal velocity of shortening, whereas swimmers and power lifters had significant augmentation of fractional shortening and velocity of shortening. Examination of the rate-corrected velocity of shortening—end-systolic stress relation revealed normal contractility with augmented systolic performance due to reduced afterload in swimmers and power lifters. Comparison of runners and control subjects revealed normal afterload but reduced preload in runners, which was manifested as reduced fractional shortening with normal afterload and contractile state.
Physiologic hypertrophy results in marked alterations in left ventricular loading conditions with secondary changes in systolic performance. When load-independent indexes are employed, the left ventricular contractile state is found to be normal in young athletes despite markedly increased left ventricular mass. Different types of exercise are associated with distinct patterns of left ventricular hypertrophy and dilation, necessitating individual assessment of preload and afterload in the interpretation of indexes of left ventricular function.
- Received April 15, 1986.
- Revision received October 1, 1986.
- Accepted October 10, 1986.
- American College of Cardiology Foundation