Exercise ManagementExercise Management

Cardiac TransplantChapter 13

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PathophysiologyCardiac transplantation represents an effective therapeutic alternative for persons with end-stage heart failure.•Almost all cardiac transplant procedures are orthotopic (placing the heart in the patients chest) in nature, performed by anastomosis of the atria of the recipient's heart to the left atria of the donor's heart.•Autonomic function of the heart is lost following transplantation. Reinnervation is possible after a period of time•Heart transplant patients have high exercise intolerance (see next slide)

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PathophysiologyCauses of Post Surgical exercise intolerance include:

•Pre-operative inactivity•Reduced aerobic characteristics of skeletal muscle•Muscle atrophy and decreased force production capacity•Pulmonary diffusion abnormalities•Left Ventricular dysfunction•Chronotropic Incompetence

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Effects on the Exercise ResponseDue to loss of autonomic control:• resting heart rate is increased (~ 20 contractions/min above age/sex-matched controls = removal of vagal tone)• chronotropic response to exercise is reduced• elevated resting blood pressure due to increase catecholamines, immunosuppressive meds., and altered baroreceptor function• decreased systolic blood pressure at peak exercise.• a greater increase is seen in plasma norepinephrine during submaximal exercise

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Effects on the Exercise Response (cont.)•Systolic and diastolic blood pressures are elevated at rest•Peak stroke volume and cardiac output are blunted during exercise (increases in HR due to preload and catecholamines) Still cardiac output at peak exercise 60-70% of normal.•Stroke volume may also be blunted because of Left Ventricular Dysfunction following transplantation.Because of the absence of vagal efferent innervation to the SA node, the increased plasma catecholamines that develop during exercise continue to exert a positive chronotropic effect in early recovery. As a result, heart rate declines slowly post exercise.

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Effects of Exercise Training•Positive physiologic and clinical adaptation have been safely demonstrated for exercise training in heart transplant patients. These include:

•Decreased blood lactate concentrations at a given workload•Improved aerobic skeletal muscle characteristics•Improved endothelial function•Decreased resting HR and BP•Increased VO2•Improved ventilatory efficiency•Counteraction of deleterious effects of Immunosuppressive Therapy •Improved strength and bone density

Management and Medication Information is FYI only.

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Recommendations for Exercise Testing (see pg. 101-102, table below)•Exercise protocols can be either ramp or steady state(3 min/stage). With the use of cycle ergometry, work ratesshould be increased by 10 to 15 watts / min or 25 to 30 watts / stage for ramp or steady-state protocols, respectively.•Steady-state exercise tests conducted with the use ofa treadmill should increase work rates by 2 METs perstage.•Because of the delayed and blunted response ofheart rate to exercise, ratings of perceived exertion and oxygen consumption should be assessed.

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Recommendations for Exercise Testing•to assess recovery following a session of maximalor submaximal exercise, observation of systolic bloodpressure is a better indicator than heart rate alone.•decentralization of the myocardium eliminates angina symptoms.•exercise electrocardiography is also inadequate with respect to assessing ischemia, as evidenced by its low sensitivity•Radionuclide testing is useful in assessing suspected ischemic heart disease.•See medication precautions to consider during exercise (pg. 103)

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Recommendations for Exercise Programming(see pg 104)•Aerobic training reestablishes self-efficacy and improves both cardiorespiratory fitness and muscle endurance•It is uncertain if aerobic training decreases the progression of atherosclerosis in the newly grafted cardiac arteries•The use of heart rate alone to guide exercise intensity is not appropriate. Instead, a RPE between 11 and 14, and 40-80% of peak VO2 should be used to guide exercise intensity.•Exercise duration should be between 15-20 minutes progressing to 60 minutes, 4-7 days per week

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Exercise ManagementExercise ManagementBecause muscle endurance and force production deficits exist in cardiac transplant recipients, a progressive resistance training program is vital.

These are important medication precautions to consider during exercise programming: • Corticosteroids may cause bone- or joint-related disorders because of demineralization effects. • Cyclosporine may cause increases in resting and submaximal blood pressure. • Start slow. Severe deconditioning is common, especially if prolonged bed rest was required prior to surgery. Intermittent exercise or short periods throughout the day may be needed until longer, continuous exercise can be tolerated.

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End of Presentation