Simultaneous evaluation of left- and right-sided heart pumping function during dynamic leg exercise in patients with mild chronic congestive heart failure, with special reference to afterload and plasma noradrenaline

Abstract

We simultaneously measured increases in mean pulmonary capillary wedge pressure (delta PCW), mean right atrial pressure (delta RA), and cardiac index (delta CI) in response to dynamic leg exercise in 81 patients with mild congestive heart failure to clarify the relationship between the left-sided and right-sided pumping function of the heart. The ratio of delta CI to delta PCW was used as an index of left-sided heart performance and the delta CI/delta RA as an index of right-sided heart performance. We also determined systemic vascular resistance, as an index of afterload on the left heart; pulmonary vascular resistance, as an index of afterload on the right heart; and the plasma level of noradrenaline before and during dynamic leg exercise. Patients with delta CI/delta PCW > 0.181/ min/m2 per mmHg were regarded as having a well functioning left heart, and the patients with delta CI/delta PCW < or = 0.181/min/m2 per mmHg as having a poorly functioning left heart. Patients with delta CI/delta RA > 0.3111/min/m2 per mmHg were regarded as having a well functioning right heart, and those with delta CI/delta RA < or = 0.311/l/min/m2 per mmHg as having a poorly functioning right heart. Patients were classified into three groups: well functioning left and right heart (normal group; n = 40), poorly functioning left and right heart (bilateral group; n = 34), and poorly functioning left heart and well functioning right heart (left-sided group; n = 7). The systemic vascular resistance index decreased during leg exercise in all patients. The decrease was smaller in the bilateral group and the left-sided group than in the normal group. The pulmonary vascular resistance index increased during exercise in the bilateral group but was unchanged in the normal group and the left-sided group. The plasma level of noradrenaline increased during exercise in all patients, but the increase was greater in the bilateral and left-sided groups than in the normal group. Pretreatment with phentolamine, an alpha-adrenoceptor antagonist, inhibited the increase in the pulmonary vascular resistance index and restored the decrease in the systemic vascular resistance index during exercise in the bilateral group. Our results showed that systemic vascular resistance, which represents afterload on the left heart, increased in the presence of impaired left-sided heart pumping function and pulmonary vascular resistance, which represents afterload on the right heart, increased in the presence of impaired right-sided heart pumping function. The inhibited decrease in systemic vascular resistance and the increase in pulmonary vascular resistance during exercise were associated with alpha-adrenoceptor-mediated vasoconstriction caused by the increase in the plasma level of noradrenaline.