Comprehensive Echocardiographic Assessment of Right Ventricular Afterload and Right Ventricular-Pulmonary Arterial Coupling in the Intensive Care Unit

Right ventricular (RV) dysfunction is common in critical illness, yet RV afterload cannot be adequately characterized by pulmonary artery systolic pressure (PASP) alone. Bedside echocardiography can estimate right atrial and pulmonary artery pressures, suggest increased pulmonary vascular resistance, and assess RV-pulmonary arterial coupling while simultaneously evaluating RV size, systolic function, septal interaction, and forward flow. Peak tricuspid regurgitation velocity combined with right atrial pressure estimates RV systolic pressure and, in the absence of outflow obstruction, approximates PASP. Pulmonary regurgitation velocities provide complementary estimates of mean and end-diastolic pulmonary artery pressure, whereas pulmonary artery acceleration time, RV outflow tract velocity-time integral, and systolic notching provide information regarding pulmonary vascular load and forward flow. A multiparametric assessment of RV systolic performance is essential because tricuspid annular plane systolic excursion, tissue Doppler systolic velocity, fractional area change, RV free-wall strain, and three-dimensional RV ejection fraction assess different aspects of contraction. The tricuspid annular plane systolic excursion/PASP ratio relates longitudinal systolic performance to pulmonary pressure but remains a surrogate of coupling, without a universal intensive care threshold. These measurements depend on image quality, loading conditions, and ventilatory support and may differ substantially from invasive hemodynamics in individual patients. Their greatest value lies in integrated physiologic assessment and serial reassessment after treatment. Echocardiography complements right heart catheterization, which remains necessary when precise hemodynamic classification or measurement of pulmonary artery wedge pressure, cardiac output, or pulmonary vascular resistance will change management.