Single-beat estimation of right ventricular contractility and its coupling to pulmonary arterial load in patients with pulmonary hypertension

Background--An accurate assessment of intrinsic right ventricular (RV) contractility and its relation to pulmonary arterial load is essential for the management of pulmonary hypertension. The pressure-volume relationship with load manipulation is the gold standard assessment used for this purpose, but its clinical application has been hindered by the lack of a single-beat method that is valid for the human RV. In the present study, we sought to validate a novel single-beat method to estimate the preload recruitable stroke work (PRSW) and its derivative for ventriculoarterial coupling in the human RV. Methods and Results--A novel single-beat slope of the PRSW relationship (M_sw) was derived by calculating the mean ejection pressure when the end-systolic volume was equal to volume-axis intercept of the PRSW relationship. In addition, by using a mathematical transformation of the equation representing the linearity of the PRSW relationship, a novel index for ventriculoarterial coupling, M_sw/mean ejection pressure, was developed. RV pressure-volume relationships were measured in 31 patients (including 23 patients with pulmonary hypertension) who were referred for right-sided heart catheterization. In this cohort, the single-beat M_sw was strongly correlated with the multiple-beat M_sw (r=0.91, P < 0.0001). Moreover, a significant correlation was observed between the single- and multiple-beat M_sw/mean ejection pressure (r=0.53, P=0.002), with a stronger correlation in those with greater RV systolic pressure (r=0.70, P=0.003). Conclusions--The novel single-beat approach provided an accurate estimation of indexes for the PRSW relationship and ventriculoarterial coupling. It may be particularly useful in assessing RV adaptation to increased pressure overload.