Hemodynamic effects of cycle ergometry versus dynamic unilateral arm exercise during right heart catheterization: a prospective observational study

Background The reintroduction of exercise pulmonary hypertension (EPH) to the pulmonary hypertension (PH) definition by the European guidelines underlines the importance of examining the hemodynamic response to exercise during right heart catheterization. Because the standard exercise modality of cycle ergometry (CE) is not universally accessible, we compared its hemodynamic effects with those of dynamic single-arm exercise (AE) in patients undergoing right heart catheterization (RHC). Methods 50 consecutive patients with indication for RHC were enrolled. Hemodynamic parameters were assessed at rest, followed by randomized exercise periods with an intervening rest phase. Thermodilution was used to determine cardiac output. The intensity of the AE was patient-determined, whereas CE was conducted at a fixed work rate ranging from 10 to 50 watts, based on the patient’s physical status. Oxygen uptake (VO₂) was estimated using the reverse Fick principle to compare relative exercise intensity between modalities. EPH was defined by an mPAP/cardiac output slope > 3 mmHg·L⁻¹·min⁻¹, and exercise-induced left heart disease by a rise in PAWP from ≤ 15 mmHg at rest to > 25 mmHg during exercise. Results Mean pulmonary arterial pressure increased by 12 mmHg with CE compared to 3 mmHg with AE (p<0.001), pulmonary artery wedge pressure increased by 5 mmHg versus 2 mmHg (p<0.001), cardiac output increased by 2.2 L/min versus 0.6 L/min (p<0.001) and mean pulmonary vascular resistance decreased by 0.05 WU with CE (p=0.761) and by 0.32 with AE (p=0.03). Estimated VO₂ during AE reached only 24% of the increase observed during CE, corresponding to an external workload equivalent of approximately 6 W. No patient showed an increase in pulmonary artery wedge pressure during exercise above 25mmHg to unmask left heart disease. In patients without PH at rest, CE led to the diagnosis of EPH in 5 patients while the used AE protocol was not suitable to detect EPH. Conclusion AE proved to be a safe exercise modality in our study but, with the protocol applied here, produced significantly smaller hemodynamic changes during RHC than CE and is thus not an adequate substitute in this form, leaving open whether an intensity-matched protocol could achieve comparable hemodynamic effects.