Athletic heart syndrome

A term given to certain cardiac and ECG changes which occur in some high performance athletes, and that probably represent physiological adaptations of the heart and cardiovascular system to the demands of the sport.The changes depend upon the nature of the demand: endurance (isotonic or dynamic) athletes such as marathon runners have chronic volume overload because of sustained increases in cardiac output (as much as seven-fold), whereas weight lifters (isometric or static athletes) experience transient episodes of enormous pressure overload. Both have cardiac enlargement. Left ventricular mass is increased as a result of increases in left ventricular diastolic cavity dimensions, thickness of the ventricular wall, or both. However, endurance athletes have increases in LV end-diastolic volume (from 120 ml in an untrained person to 220 ml in a resting athlete) and stroke volume (up to 170 ml during exercise), with proportionate, but mild, increases in ventricular wall thickness. Although it was previously thought that pure power training considerably increased LV wall thickness, a recent study showed that although LV mass was increased, the increase in absolute wall thickness was modest and rarely exceeded the upper limits of normal (Pelliccia et al 1993). From an echocardiography study of 100 weight-trained, young athletes, the authors found that increases in LV wall thickness above 12 mm were unusual, and concluded that, if it was uneven in distribution, and exceeded 16 mm, a pathological cause should be sought.

In either case, when cardiac abnormalities occur, the main problem is to differentiate these from pathological heart disease, in particular, hypertrophic cardiomyopathy (HCM).This is increasingly recognised as an important cause of sudden death in young people, a number of whom have a family history (Editorial 1992).

However, those with 'athlete's heart' are not immune from problems, since the cardiovascular changes which prepare athletes for exercise may be disadvantageous during anaesthesia and surgery. In a study of normotensive athletes with cardiac hypertrophy, impairment of cardiopulmonary receptor reflexes was found (Giannattasio et al 1990).This indicates a potential lack of appropriate response to haemorrhage or orthostatic stress by means of a tachycardia.

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