Chronic prostanoid therapies demonstrate functional, hemodynamic, and mortality benefits in patients with pulmonary hypertension (PH). Right ventricular (RV) function is an important predictor of morbidity and mortality in PH. The aim of this study is to investigate acute RV mechanical dispersion (RV-MD) response to inhalation of iloprost in patients with PH on chronic iloprost inhalation therapy.
Two-dimensional speckle-tracking strain analysis was used to calculate RV-MD before and after inhalation of iloprost in 16 patients with PH on chronic iloprost therapy (11 idiopathic pulmonary arterial hypertension and 5 chronic thromboembolic pulmonary hypertension; 10 women and 6 men; mean age, 38.5 ± 10.2 years). Contraction duration was measured as the time in msec from onset R wave on ECG to peak RV shortening by strain. RV-MD was defined as the standard deviation of contraction duration a six segment RV model (three RV free wall plus three septal segments). Before iloprost inhalation tricuspid annular plane systolic excursion, mean pulmonary artery pressure and 6-minutes walking distance were also recorded.
Comparison of RV-MD before and after iloprost inhalation revealed a significant improvement in RV-MD after the iloprost inhalation (58.2 ± 5.4 msec vs. 51.3 ± 6.4 msec, respectively; p<0.01). The mean difference in RV-MD (ΔRV-MD) was 6.9 ± 3.4 msec. There were significant positive correlations between ΔRV-MD and 6-minutes walking distance (rs = 0.95, p < 0.001) and tricuspid annular plane systolic excursion (rs = 0.84, p < 0.001), and significant negative correlation with mean pulmonary artery pressure (rs = -0.65, p < 0.01).
RV-MD significantly improves in patients with PH on chronic iloprost inhalation therapy after each inhalation, and ΔRV-MD is significantly correlated with tricuspid annular plane systolic excursion, 6-minutes walking distance and mean pulmonary artery pressure.