Cardiac transplantation has emerged as a viable therapeutic strategy for select patients with end-stage heart disease, offering extended survival and improved quality of life. Ref 1.
While life expectancy is greatly improved after a heart transplant, survival is still limited, and compared to the general population, the exercise capacity and health-related quality of life of heart transplant recipients are reduced. Nevertheless, closely monitored exercise is still indicated as part of their rehabilitation program and an increased exercise capacity is associated with a better prognosis following transplant surgery. Ref 2.
In contrast to the positive chronotropic response (increase in heart rate) of a normal heart to exercise, a newly transplanted heart is denervated, which causes higher resting heart rate (HR) and higher blood pressure as well but a reduced HR response (chronotropic incompetence) to exercise i.e. there is a significantly slower increase of the HR at onset of exercise, a reduced peak HR, and a delayed return towards resting values after cessation of exercise (During submaximal exercise, the stroke volume is greater than normal but the cardiac output is somewhat reduced. Peak heart rate, peak stroke volume, and peak cardiac output are all less than in age-matched normals). However, an improved HR response to exercise is typically demonstrated during the first year after surgery. Ref 3.
As in all cases where HR cannot reliably be used to determine the intensity and effects of exercise, the Borg RPE (Rate of perceived exertion) is highly recommended as a safe alternative means of determining HR and exercise intensity in cardiac transplant patients who are undergoing exercise rehabilitation.
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