Importance of training-induced effects on the arterial vascular system andthe skeletal musculature in the therapy regime of congestive heart failureNYHA II/III

Dynamic muscular exercise performed by healthy subjects leads to a rise in the left ventricular blood ejection with an acute increase in the local wal l shear stress on the endothelium of the arterial vessels. These hemodynami c changes results in a release of endothelium-dependent relaxing factors, o ne of them concerns nitric oxide (NO). Therefore an arterial vasodilatation with an acute increase in the blood flow volume to the exercising muscle g roups occurs. If more than 1/6 of the skeletal musculature is involved in e xercise and if training duration exceeds 3-5 hours a week the chronically i ncreased blood flow volume in the cardiovascular system triggers structural and functional changes of the heart and the arterial vessels. It develops a functional intact excentric hypertrophy of the myocardium; within the art erial vessels an increase in the diameter of the muscular arteries supplyin g the trained muscle groups occurs. These training-induced adaptations of t he cardiovascular system are adjusted to improve the aerobic skeletal muscl e metabolism. In congestive heart failure a pathological excentric myocardial hypertrophy is found. In this case the systolic myocardial function is impaired and th e left ventricular ejection fraction is reduced already in early stages, so that the cardiac output can not be sufficiently increased during exercise. In addition a dysfunction of the endothelium of the arterial vessels occur s. As a consequence the endothelium-dependent arterial vasodilatation is re duced, so that the peripheral arteries could not supply the muscle groups i nvolved in exercise with enough blood flow volume. Therefore, the acute del ivery of the working musculature with oxygen and energy substrates is insuf ficient, so that premature muscular fatigue occurs. The reduced exercise re sistance of the patients leads chronically to a generalized skeletal muscle atrophy. Ultrastructural analysis revealed a decrease of oxidative type 1 muscle fibers with a relative increase of more glycolytic type 2 fibers. In addition, the volume density and the surface area of the cristae of mitoch ondria are reduced. All these changes results in a decrease of aerobic skel etal muscle metabolism independent of the blood flow volume, so that the ph ysical fitness of the patients progressively decline. On the basis of the t raining-induced physiological adaptations of the cardiovascular system, a s pecial exercise therapy supervised by a physician was developed for patient s with congestive heart failure NYHA II/III. It have been shown that variou s exercise programs, which are adjusted to the degree of cardiac function i mpairment are suitable to restore the endothelial dysfunction of the arteri al vessels as well as to cure the disturbed skeletal muscle metabolism in t hese patients independent of an improvement of cardiac function. Therefore in patients with congestive heart failure NYHA II/III who underwent regular ly such an exercise therapy, the secondary impaired physical fitness could be rebuild without an excessive risk for an acute exercise-induced cardiova scular emergency.