Acute effects of inhaled iloprost on intracardiac conduction in patients with pulmonary arterial hypertension.

Background: Pulmonary arterial hypertension (PAH) is a severe, life-threatening disorder despite the availability of specific drug therapy. A lack of endogenous prostacyclin secondary to downregulation of prostacyclin synthase in PAH may contribute to vascular pathologies. Therefore, prostacyclin and its analogs including inhaled iloprost may decrease pulmonary arterial pressure and ventricular pressure.

Methods: Here, we studied that acute effects of iloprost used in pulmonary vasoreactivity testing on the intracardiac conduction system in patients with PAH. A total of 35 (15 idiopathic PAH, 20 congenital heart disease) patients with PAH were included in this prospective study. Patients were divided into two groups: 22 patients with negative pulmonary vasoreactivity in group 1 and 13 with positive pulmonary vasoreactivity in group 2. Electrophysiological parameters including basic cycle length, atrium-His (AH) interval, His-ventricle (HV) interval, PR interval, QT interval, QRS duration, Wenckebach period, and sinus node recovery time (SNRT) were evaluated before and after pulmonary vasoreactivity testing in both groups.

Results: The AH interval (81 [74-93]; 80 [65.5-88], p = 0.019) and SNRT (907.7 ± 263.4; 854.0 ± 288.04, p = 0.027) was significantly decreased after pulmonary vasoreactivity testing. Mean right atrium pressure was found to be correlated with baseline AH (r = 0.371, p = 0.031) and SNRT (r = 0.353, p = 0.037).

Conclusion: Inhaled iloprost can improve cardiovascular performance in the presence of PAH, primarily through a reduction in right ventricular afterload and interventricular pressure. Decreased pressure on the interventricular septum and ventricles leads to conduction system normalization including of the AH interval and SNRT due to resolution of inflammation and edema.