The Role of Oxygen Extraction in Peripheral Tissues in Exercise Capacity in Chronic Heart Failure

Abstract

To elucidate the role of oxygen extraction during exercise in chronic heart failure (CHF), 26 patients underwent the symptom-limited maximal exercise. Hemodynamics, oxygen uptake (V02) and blood gas were examined during exercise. Group I (n = 16, V02max<20 ml/min/kg) showed severe cardiac dysfunction during exercise compared with group II (n = 10, V02max^20 ml/min/kg). Though V02was similar in both groups at rest and with a 25-watt load, oxygen extraction was significantly higher in group I than in group II. At the maximal work load, V02maxwas significantly lower in group I, whereas there was no significant difference in oxygen extraction between the two groups. With a 25-watt load, mixed venous partial oxygen tension was similar, however, oxygen saturation was significantly lower in group I. It was concluded that oxygen extraction during exercise rapidly increased in group I, and this may play an important role in the maintenance of exercise capacity during mild physical activity in CHF. © 1990, The Japanese Society of Internal Medicine. All rights reserved.