Page 168 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt

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Abstract
Introduction: Exercise tolerance is decreased in patients with pulmonary hypertension (PH). It is unknown whether exercise intolerance in PH coincides with an impaired rest-to-exercise response in right ventricular (RV) contractility. Therefore, the aim of this study was to investigate in PH patients the RV exertional contractile reserve, defined as the rest-to-exercise response in end-systolic elastance (ΔEes), and the effects of exercise on the matching of Ees and RV afterload (Ea), i.e. RV- arterial coupling (Ees/Ea). In addition, we compared ΔEes with a recently proposed surrogate, the rest-to-exercise change in pulmonary artery pressure (ΔPAP).
Methods: We prospectively included 17 patients with precapillary PH and 7 no-PH control subjects who performed an submaximal invasive cardiopulmonary exercise test between January 2013 and July 2014. Ees and Ees/Ea were assessed using single beat pressure-volume loop analysis.
Results: Exercise data in 16 PH patients and 5 no-PH control subjects were of sufficient quality for analysis. Ees significantly increased from rest-to-exercise in control subjects, but not in PH patients. Ea significantly increased in both groups. As a result, exercise led to a decrease in Ees/Ea in PH patients while Ees/Ea was unaffected in control subjects (p-interaction=0.009). In PH patients, ΔPAP was not related to ΔEes, but significantly correlated to the rest-to-exercise change in heart rate (ΔHR).
Conclusions: In contrast to controls, PH patients were unable to increase Ees during submaximal exercise. Failure to compensate for the further increase in Ea during exercise led to a deterioration in Ees/Ea. Furthermore, ΔPAP did not reflect ΔEes, but rather ΔHR.