VENTILATORY AND HEART-RATE RESPONSES AFTER EXERCISE IN CHRONIC CARDIAC-FAILURE

1. To determine if the recovery period after exercise is abnormal in c hronic cardiac failure, we studied 15 patients with stable chronic car diac failure, and 14 normal subjects during and after symptom-limited maximal treadmill exercise. 2. In patients, O-2 consumption fell expon entially from 16.8 (13.7-20.0) ml min(-1) kg(-1) at peak exercise to 6 .0 (5.2-6.7) ml min(-1) kg(-1) at 3 min of recovery and in control sub jects it fell from 30.2 (27.0-33.5) ml min(-1) kg(-1) to 6.7 (5.9-7.4) ml min(-1) kg(-1) (mean and 95% confidence intervals). The associated decay constants were slower in patients [0.70 (0.58-0.83) min(-1) ver sus 0.93 (0.81-1.05) min(-1) in control subjects (P<0.01, t-test)]. 3. CO2 consumption kinetics displayed similar abnormalities [(k: 0.55 (0 .41-0.69) min(-1) versus 0.71 (0.59-0.83) min(-1), P<0.05)] and heart rate kinetics showed a similar trend [(k: 0.53 (0.33-0.74) min(-1) ver sus 0.76 (0.62-0.89) min(-1), P=0.08]. 4. We conclude that patients wi th cardiac failure recover more slowly from exercise than normal subje cts, and that this may further impair their ability to perform exercis e, with consequent effect on quality of life.