Fig 1.
Workflow for pressure–volume (PV) loop reconstruction using transthoracic echocardiography.
Left ventricular endocardial contours are traced in the 2-, 3-, and 4-chamber views. From these data, volume–time curves are derived and combined with patient-specific brachial systolic pressure. Dedicated software applies a physics-based model to integrate imaging-derived volumes with cuff-measured pressure and reconstruct the end-systolic and end-diastolic PV relations.
Fig 2.
Pressure-Volume (PV) loop of the left ventricle: the graphical representation of the pressure and volume relationship in the left ventricle during cardiac cycle with the derived parameters: V0, theoretical volume at zero pressure; ESV/EDV, end-systolic and end-diastolic volume; ESP/EDP, end-systolic and end-diastolic pressure; ESPVR/EDPVR, end-systolic and end-diastolic pressure-volume relationships; Pmin/Pmax, minimum and maximum brachial pressure; Ea, effective arterial elastance; Ees, end-systolic elastance; PE, potential energy; PVA, pressure volume area; SW, stroke work; WE, work efficiency.
Table 1.
Demographic and clinical characteristics of the study group (n = 25).
Table 2.
Echocardiographic parameters of the patients.
Table 3.
Inter- and intra-observer variability for PV loop derived parameters.
Fig 3.
Bland-Altman plots for the of inter-observer variability in end-systolic elastance (Ees), effective arterial elastance (Ea), ventriculo-arterial coupling (VAC), stroke work (SW), pressure volume area (PVA), and work efficiency (WE).
Fig 4.
Bland-Altman plots for the of intra-observer variability in end-systolic elastance (Ees), effective arterial elastance (Ea), ventriculo-arterial coupling (VAC), stroke work (SW), pressure volume area (PVA), and work efficiency (WE).
Table 4.
Sample size calculation for the PV loop parameters to detect 10, 15, and 20% relative change compared to the mean values of the first reader with 90% power and α error of 0.05.
Fig 5.
Sample size calculation for the PV loop parameters.
Number of the patients needed for end-systolic elastance (Ees), effective arterial elastance (Ea), ventriculo-arterial coupling (VAC), stroke work (SW), pressure volume area (PVA), and work efficiency (WE) to detect the relative percent change in mean values.