日本小児循環器学会雑誌 Pediatric Cardiology and Cardiac Surgery

The normal pulmonary vascular bed is a low-pressure, low-resistance, and high-compliance system. In healthy participants, favorable right ventricle (RV)-to-pulmonary artery (PA) coupling matches RV contractility and RV afterload. RV dysfunction is the most significant predictor of poor prognosis in patients with pulmonary arterial hypertension (PAH). The gold standard for evaluating RV–PA coupling is right heart catheterization, which acquires pressure and volume. Pressure–volume loop-derived end-systolic elastance (Ees) and end-systolic arterial elastance (Ea). RV–PA coupling is the Ees/Es ratio, and a decreased Ees/Ea ratio is a powerful factor in RV dysfunction. The tricuspid annular plane systolic excursion (TAPSE) and estimated systolic pulmonary artery pressure (SPAP) combination has been proposed as a significant prognostic factor in PAH, and the TAPSE/SPAP ratio is a noninvasive index of RV–PA coupling. In compensated states, the RV contractile increases when the afterload increases. In contrast, in decompensated states, the RV contractile function no longer increases when the afterload increases, thereby resulting in lower RV–PA coupling ratios. In patients with severe PAH, early and accurate RV–PA coupling evaluation is essential for clinical decision making.