Reliability of pressure-volume loop parameters derived from transthoracic echocardiography in patients undergoing hemodialysis.

BACKGROUND

The pressure-volume (PV) relationship remains a key tool for assessing cardiac function. PV loop derived parameters, including end-systolic elastance (Ees), effective arterial elastance (Ea), ventriculo-arterial coupling (VAC), stroke work (SW), pressure-volume area (PVA), and work efficiency (WE), are valuable tools, but reproducibility data are scarce.

OBJECTIVE

To evaluate the inter- and intra-observer variability of PV loop parameters derived from transthoracic echocardiography images in patients undergoing hemodialysis.

METHODS

Twenty-five adult patients with end-stage renal disease undergoing maintenance hemodialysis were randomly selected. PV loops were reconstructed using Q-Strain software (version 1.3.0.79, Medis, Leiden, the Netherlands), and parameters including Ees, Ea, VAC, SW, PVA, and WE were calculated. Two experienced readers performed measurements for inter-observer analysis; one reader repeated measurements one week apart for intra-observer analysis. Reliability was assessed using intraclass correlation coefficients (ICC) and Bland-Altman plots.

RESULTS

Inter-observer agreement was excellent for SW 0.96 (0.91-0.98) and PVA 0.95 (0.87-0.98), good for Ees 0.90 (0.77-0.96) and Ea 0.79 (0.49-0.91), and moderate for VAC 0.68 (0.23-0.85) and WE 0.72 (0.28-0.79). Intra-observer agreement was excellent for Ees 0.96 (0.90-0.98), Ea 0.98 (0.94-0.99), SW 0.98 (0.96-0.99) and PVA 0.98 (0.96-0.99), and good for VAC 0.78 (0.51-0.91) and WE 0.85 (0.65-0.94). Bland-Altman analysis showed minimal bias for Ees, SW and PVA, whereas Ea, VAC and WE exhibited proportional bias.

CONCLUSIONS

PV loop-derived parameters obtained via transthoracic echocardiography demonstrate good-to-excellent reproducibility, particularly for Ees, Ea, SW and PVA. VAC and WE show moderate variability, suggesting careful interpretation of these parameters in clinical and research settings.