Abstract 13576: Difference in Right Ventricular Loading Between Patients With Pulmonary Hypertension and Patients With Left Sided Heart Failure
Purpose: Patients with pulmonary hypertension (PH) associated with right ventricular (RV) dysfunction show poor prognosis. To elucidate the mechanism of RV dysfunction, we compared RV function, RV load and RV-pulmonary artery (PA) coupling between patients with PH and those patients with left-sided heart failure (HF).
Methods: Study population consisted of 14 patients with chronic PH (PH group; 40 ± 17 years old, 10 females and 4 males) of WHO functional class 2 and 10 patients with left-sided HF of NYHA-2 (HF group; 75 ± 10 years old, 2 females and 8 males). All patients underwent simultaneous RV pressure-wire and Swan-Ganz study. We measured cardiac index, max +dP/dt and Vmax to assess RV systolic function, and maximum -dP/dt and tau to assess RV diastolic function. Contractile element velocity (Vce) during isovolumic period was derived as (dP/dt)/kP, where k = 24 /cm. Extrapolated Vmax was calculated from plots of Vce and RV pressure, which relationship was assumed as liner regression. We measured effective arterial elastance (Ea; (peak RV pressure — RVEDP)/stroke volume) of PA, and RV-PA coupling index (Vmax / Ea).
Results: Mean PA pressure was significantly higher in PH group than in HF group (50 ± 14 vs. 19 ± 7 mmHg, P < 0.001) although cardiac index was not different (2.6 ± 0.7 vs. 2.7 ± 0.5 L·min-1·m-2, P = 0.891). Vmax was comparable between PH and HF groups (1.61 ± 0.48 vs. 1.32 ± 0.57 lengths/sec, P = 0.205). Ea was significantly higher in PH group (1.4 ± 0.9 vs. 0.4 ± 0.1 mmHg/mL, P = 0.001). RV-PA coupling index was significantly decreased in PH group (1.6 ± 0.5 vs. 3.8 ± 1.6, P = 0.001).
Conclusion: In patients with PH, RV systolic function (Vmax) is comparable to patients with left-sided HF, but PA is more stiff (elevated Ea), resulting in a decrease in RV-PA coupling index. The afterload mismatch of RV may be a main cause of rapid progression of RV dysfunction in the early stage of patients with PH. Reducing Ea of PA may be main therapeutic strategy in patients with PH.
- © 2010 by American Heart Association, Inc.