Heart disease may limit exercise tolerance by

A. True This is the main mechanism limiting exercise.

B. False It decreases ejection fraction and hence stroke volume and cardiac output.

C. True This causes temporary (angina) and potentially permanent (myocardial infarc-tion) dysfunction.

D. False It may decrease heart rate by blocking impulses from the sinoatrial node to the ventricles.

E. True It decreases work done at a given fibre length on the left ventricular function curve.