Right ventricular (RV) function and its adaptation to increased afterload [RV–pulmonary arterial (PA) coupling] are crucial in various types of pulmonary hypertension, determining symptomatology and outcome. In the course of disease progression and increasing afterload, the right ventricle undergoes adaptive remodelling to maintain right‐sided cardiac output by increasing contractility. Exhaustion of compensatory RV remodelling (RV–PA uncoupling) finally leads to maladaptation and increase of cardiac volumes, resulting in heart failure. The gold‐standard measurement of RV–PA coupling is the ratio of contractility [end‐systolic elastance (Ees)] to afterload [arterial elastance (Ea)] derived from RV pressure–volume loops obtained by conductance catheterization. The optimal Ees/Ea ratio is between 1.5 and 2.0. RV–PA coupling in pulmonary hypertension has considerable reserve; the Ees/Ea threshold at which uncoupling occurs is estimated to be ~0.7. As RV conductance catheterization is invasive, complex, and not widely available, multiple non‐invasive echocardiographic surrogates for Ees/Ea have been investigated. One of the first described and best validated surrogates is the ratio of tricuspid annular plane systolic excursion to estimated pulmonary arterial systolic pressure (TAPSE/PASP), which has shown prognostic relevance in left‐sided heart failure and precapillary pulmonary hypertension. Other RV–PA coupling surrogates have been formed by replacing TAPSE with different echocardiographic measures of RV contractility, such as peak systolic tissue velocity of the lateral tricuspid annulus (S′), RV fractional area change, speckle tracking‐based RV free wall longitudinal strain and global longitudinal strain, and three‐dimensional RV ejection fraction. PASP‐independent surrogates have also been studied, including the ratios S′/RV end‐systolic area index, RV area change/RV end‐systolic area, and stroke volume/end‐systolic volume. Limitations of these non‐invasive surrogates include the influence of severe tricuspid regurgitation (which can cause distortion of longitudinal measurements and underestimation of PASP) and the angle dependence of TAPSE and PASP. Detection of early RV remodelling may require isolated analysis of single components of RV shortening along the radial and anteroposterior axes as well as the longitudinal axis. Multiple non‐invasive methods may need to be applied depending on the level of RV dysfunction. This review explains the mechanisms of RV (mal)adaptation to its load, describes the invasive assessment of RV–PA coupling, and provides an overview of studies of non‐invasive surrogate parameters, highlighting recently published works in this field. Further large‐scale prospective studies including gold‐standard validation are needed, as most studies to date had a retrospective, single‐centre design with a small number of participants, and validation against gold‐standard Ees/Ea was rarely performed.

Aims We sought to assess the feasibility of constructing right ventricular (RV) pressure–volume (PV) loops solely by echocardiography. Methods and results We performed RV conductance and pressure wire (PW) catheterization with simultaneous echocardiography in 35 patients with pulmonary hypertension. To generate echocardiographic PV loops, a reference RV pressure curve was constructed using pooled PW data from the first 20 patients (initial cohort). Individual pressure curves were then generated by adjusting the reference curve according to RV isovolumic and ejection phase duration and estimated RV systolic pressure. The pressure curves were synchronized with echocardiographic volume curves. We validated the reference curve in the remaining 15 patients (validation cohort). Methods were compared with correlation and Bland–Altman analysis. In the initial cohort, echocardiographic and conductance-derived PV loop parameters were significantly correlated {rho = 0.8053 [end-systolic elastance (Ees)], 0.8261 [Ees/arterial elastance (Ea)], and 0.697 (stroke work); all P < 0.001}, with low bias [−0.016 mmHg/mL (Ees), 0.1225 (Ees/Ea), and −39.0 mmHg mL (stroke work)] and acceptable limits of agreement. Echocardiographic and PW-derived Ees were also tightly correlated, with low bias (−0.009 mmHg/mL) and small limits of agreement. Echocardiographic and conductance-derived Ees, Ees/Ea, and stroke work were also tightly correlated in the validation cohort (rho = 0.9014, 0.9812, and 0.9491, respectively; all P < 0.001), with low bias (0.0173 mmHg/mL, 0.0153, and 255.1 mmHg mL, respectively) and acceptable limits. Conclusion The novel echocardiographic method is an acceptable alternative to invasively measured PV loops to assess contractility, RV-arterial coupling, and RV myocardial work. Further validation is warranted.