Submaximal Exercise Pulmonary Gas Exchange in Left Heart Disease Patients With Different Forms of Pulmonary Hypertension

•Pulmonary vascular pressure and gas exchange were assessed during exercise in CHF.•Pulmonary gas exchange abnormalities were associated with pulmonary hypertension (PH).•Exercise gas exchange may allow differentiation of PH type in CHF

BackgroundWe determined whether pulmonary gas exchange indices during submaximal exercise are different in heart failure (HF) patients with combined post- and pre-capillary pulmonary hypertension (PPC-PH) versus HF patients with isolated post-capillary PH (IPC-PH) or no PH.Methods and ResultsPulmonary hemodynamics and pulmonary gas exchange were assessed during rest and submaximal exercise in 39 HF patients undergoing right heart catheterization. After hemodynamic evaluation, patients were classified as having no PH (n = 11), IPC-PH (n = 12), or PPC-PH (n = 16). At an equivalent oxygen consumption, end-tidal CO2 (PETCO2) and arterial oxygen saturation (SaO2) were greater in no-PH and IPC-PH versus PPC-PH patients (36.1 ± 3.2 vs 31.7 ± 4.5 vs 26.2 ± 4.7 mm Hg and 97 ± 2 vs 96 ± 3 vs 91 ± 1%, respectively). Conversely, dead-space ventilation (VD/VT) and the ventilatory equivalent for carbon dioxide (V˙E/V˙CO2ratio) were lower in no-PH and IPC-PH versus PPC-PH patients (0.37 ± 0.05 vs 0.38 ± 0.04 vs 0.47 ± 0.03 and 38 ± 5 vs 42 ± 8 vs 51 ± 8, respectively). The exercise-induced change in VD/VT, V˙E/V˙CO2 ratio, and PETCO2 correlated significantly with the change in mean pulmonary arterial pressure, diastolic pressure difference, and transpulmonary pressure gradient in PPC-PH patients only.ConclusionsNoninvasive pulmonary gas exchange indices during submaximal exercise are different in HF patients with combined post- and pre-capillary PH compared with patients with isolated post-capillary PH or no PH.