Right Ventricular Structure and Function During Exercise

Abstract

Right ventricular (RV) function is relatively unimportant in the healthy circulation at rest when little work is required to generate flow across the low-resistance and high compliance pulmonary circulation. However, during exercise RV work increases disproportionately. Even in healthy subjects, pulmonary artery pressures increase with exercise intensity due to an increase in left atrial pressure and limitation in vascular recruitment, dilation and distension within the pulmonary vasculature. This increase in afterload during exercise demands an increase in RV contractility if normal ventricular-arterial coupling is to be maintained and stroke volume is to increase during exercise. The assessment of RV function during exercise is therefore of great interest, but is difficult. Recent advances and novel approaches to echocardiographic and magnetic resonance imaging provide excellent tools with which to quantify changes in RV function during exercise. RV stroke volume increases during exercise in healthy subjects in spite of the exercise-induced increases in afterload. However, if exercise is prolonged it seems that RV dysfunction develops as evidenced by the consistent demonstration of RV impairment after endurance exercise. In patients with pathological increases in RV afterload, the RV may be observed to dilate and fail early during exercise and may explain symptom severity better than resting measures. Pulmonary vasodilator therapy has been demonstrated to improve exercise capacity in patients with increases in pulmonary vascular resistance and in healthy subjects at altitude, but not in healthy subjects at sea level. Assessments of cardiac performance during exercise cannot ignore the RV and pulmonary circulation.