Page 68 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt

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Figure 1: Pressure-volume loop. Pes = end-systolic pressure; mPAP = mean pulmonary artery pressure; Pmax = maximal isovolumic pressure; ESPVR = end-systolic pressure volume relationship; Ees = RV contractility; Ea = pulmonary vascular resistance; SV = stroke volume. Adapted from [6].
From the pressure-volume relationship it is also possible to derive the resistance of the pulmonary vascular system. The slope of the line connecting the end-systolic and end-diastolic point, the Ea (mPAP/SV), is a measure of pulmonary vascular resistance and therefore a measure of afterload on the RV (figure 1). Coupling of the RV to its load (RV-A coupling) is calculated as Ees/Ea (Figure 1), and this ratio is believed to reflect cardiac efficiency [44].