THE ROLE OF RIGHT AND LEFT-VENTRICULAR FUNCTION IN THE VENTILATORY RESPONSE TO EXERCISE IN CHRONIC HEART-FAILURE

Background Right ventricular function may be an important determinant of exercise capacity, peak oxygen consumption (VO2), and the ventilato ry response to carbon dioxide production (VE/VCO2 relation) in patient s with chronic heart failure (CHF). Methods and Results We studied the role of right ventricular function in CHF and also investigated the e ffects of absent right ventricular reserve in patients previously oper ated on with Fontan's procedure by measuring metabolic gas exchange du ring exercise in five groups of patients: (1) 10 patients who had prev iously undergone Fontan's procedure for congenital heart disease in wh om the right ventricle is not functional; (2) 11 age-matched control s ubjects with dilated cardiomyopathy (DCM); (3) 15 age-matched normal s ubjects; (4) 42 patients with CHF; and (5) 16 age-matched control subj ects. Left and right ventricular ejection fractions (LVEF and RVEF) we re measured by radionuclide ventriculography in group 4. In the young subjects, the VE/VCO2 slope was lower in the control subjects than in the other two groups, being 24.4+/-4.3 against 33.3+/-6.6 in group 1 ( P<0.01) and 29.6+/-8.1 in group 2 (P<.05). The correlation between pea k VO2 and VE/VCO2 was -0.80 (P=.005) in group 1 and -0.76 (p=.007) in group 2. In the older age groups, the VE/VCO2 slope was significantly greater (38.0+/-14.9 versus 25.4+/-3.7; P<.001) in the heart failure g roup (group 4). In neither control group was there a significant relat ion between peak VO2 and VE/VCO2 slope. In group 4, the relation betwe en peak VO2 and VE/VCO2 was similar to that seen for groups 1 and 2. L VEF was 24.3+/-14.1%, and RVEF was 32.5+/-13.1%. There was no correlat ion between either RVEF or LVEF and peak VO2 or VE/VCO2 slope in the h eart failure group. Conclusions The relation between excessive ventila tion and reduction in peak oxygen consumption is present in patients w ith no functioning right ventricle. RVEF is not a determining feature of either exercise capacity or the excessive ventilatory response in C HF.