Central Hemodynamic and Gas Exchange Adaptions to Training in Chronic Heart Failure

Background. Exercise Training has just recently been recognized as an important therapeutic modality in patients with chronic heart failure (CHF). However, central hemodynamic adaptations to exercise training in patients with CHF remain unclear. Methods. Seventeen patients with first diagnosis of CHF (56 ± 5 years, mean EF = 32 ± 6%) were randomized to an exercise raining group (N = 8), or control group (N = 9). Patients in the exercise group performed two hours of daily walking along with five sessions per week of high intensity monitored stationary cycling (40 minutes at 70 to 80% peak capacity) at residential rehabilitation center for period of two months. Control patients received usual community care. Ventilatory gas exchange and upright hemodynamic measurements (rest and peak exercise cardiac output, pulmonary artery, wedge, and mean arterial pressures, and systemic vascular resistance) were performed before and after the study period. Results. Changes in oxygen uptake at maximal exercise and the lactate threshold (LT) were as follows: The increase in VO2 max in the trained group paralleled an increase in maximal cardiac output (11.8 pre vs. 12.8 l/min post, p < 0.05), but maximal cardiac output did not change in controls. None of the hemodynamic pressures at rest or during exercise differed within or between groups. All of the increase in VO2 max occurred during the first month of training, whereas significant increases in VO2 LT were observed after both months. Both blood lactate and perceived exertion levels were significantly lower at matched ramp work rates after raining. Conclusion. Training benefits occur early in the course of rehabilitation in CHF and are mediated through increases in maximal cardiac output, but not central hemodynamic status. Training longer than one month after the onset of CHF does not increase VO2 max further, but may provide further increases in VO2 LT.