REDUCTION OF SYMPATHETIC DRIVE DURING REST AND ACTIVITY AFTER INTENSE EXERCISE THERAPY IN CARDIAC REHABILITATION 953

Abstract

An increased sympathetic drive may trigger myocardial hyperstimulation and arthythmias. Intense exercise training improves function and perfusion of the myocard and the skeletal muscles. It also reduces neurohormonal output. The goal of our study was to examine the effects of a 6 months intense exercise therapy integrated in an ambulatory cardiac rehabilitation program on carecholamine output at rest, during and after exercise. 13 patients with coronary artery disease (after bypass surgery. PTCA or myocardial infarction; 58±5 years, 172±8 cm, 72±10 kg) performed intense exercise therapy 4.2±0.4 times per week, 30 min each. Before and after 6 months of rehabilitation two successive incremental tests on a cycle ergometer were performed. Epinephrine (E), norepinephrine (NE), blood lactate(Lac), and heart rate (HR) were measured at rest, during and 5 min after both tests. NE and E elimination from the blood were calculated from the difference at the end of the test and 5 min after the test. Exercise therapy increased endurance training capacity by 48±15% (before 75±28 W: after 6 months 103±32 W, mean HR were nearly identical). In the incremental tests before and after rehabilitation maximal workload was significantly increased from 1.89±0.5 to 2.32±0.51 W per kg body weight. At a submaximal, comparable intensity (80 W) Lac and HR were significantly reduced from 2.3±1.0 to 1.7±0.6 mmol/l and from 113±18 to 106±17 b min. The results of NE and E are listed in thetable. Intense exercise therapy in patients with CAD, which increases endurance capacity by 40-50%, diminishes significantly the sympathetic drive during test and also during exercise. The possibility of a faster elimination of increased catecholamines from the blood could result in a higher tolerance against neurohormonal induced myocardial ischemia or arrhythmia.