[Adaptation of the denervated heart to physical effort]

In a transplanted heart, increased stroke volume secondary to the Starling mechanism and increased heart rate and contractility secondary to noradrenaline effect appear sequentially whereas they appear simultaneously in normal innervated heart. Cardiac output adaptation at exercise is thus delayed and responsible for metabolic acidosis and abnormally high exercise ventilation. Moreover, stroke volume adaptation to exercise is compromised by abnormally high right and left afterload and by systolic and diastolic impairement of the ventricular function related with chronic rejections' episodes.