Assessment of Right Ventricular-Pulmonary Arterial Coupling in Schistosomiasis-Associated Pulmonary Arterial Hypertension

Pulmonary Arterial Hypertension is a progressive and potentially fatal cardiopulmonary disorder characterized by remodeling of the pulmonary vasculature, progressive elevation of pulmonary vascular resistance (PVR), and eventual right ventricular (RV) failure.

According to the 2022 European Society of Cardiology/European Respiratory Society (ESC/ERS) guidelines, pulmonary hypertension is currently defined hemodynamically by a mean pulmonary arterial pressure (mPAP) >20 mmHg measured by right heart catheterization, while pulmonary arterial hypertension is additionally characterized by pulmonary arterial wedge pressure (PAWP) ≤15 mmHg and PVR >2 Wood units.

Schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH) is classified within Group 1 PAH and represents one of the most important causes of PAH in endemic regions, particularly in developing countries such as Egypt and Brazil.

Schistosomiasis is considered the second most prevalent parasitic disease worldwide after malaria, affecting more than 200 million individuals globally. Chronic hepatosplenic schistosomiasis may lead to porto-systemic shunting, allowing parasite eggs to embolize into the pulmonary circulation, triggering chronic inflammation, endothelial dysfunction, and pulmonary vascular remodeling.

The pathological changes observed in Sch-PAH resemble those seen in idiopathic PAH, including medial hypertrophy, intimal fibrosis, and plexiform lesions. However, several studies suggest that patients with Sch-PAH may exhibit better long-term survival compared with idiopathic PAH despite comparable pulmonary hemodynamic impairment.

The mechanisms underlying this relatively favorable prognosis remain incompletely understood.

Right ventricular adaptation to increased afterload is currently recognized as one of the principal determinants of prognosis in PAH.