Intraoperative right ventricular end-systolic pressure-volume loop analysis in patients undergoing cardiac surgery: A proof-of-concept methodology

Background: Perioperative right ventricular (RV) dysfunction is associated with increased morbidity and mortality in cardiac surgery patients. This study aimed to demonstrate proof of concept in generating intraoperative RV pressure-volume (PV) loops and conducting an end-systolic PV relationship (ESPVR) analysis using data obtained from routinely used intraoperative monitors.

Methods: Adult patients undergoing cardiac surgery with the placement of a pulmonary artery catheter (PAC) between May 2023 and March 2024 were included prospectively. The PV loops were generated using 3-dimensional echocardiographic RV volume data and continuous RV pressure data obtained from a PAC. The volume-time and pressure-time curves were digitized using the semiautomatic WebPlotDigitizer program and synchronized to reconstruct an RV PV loop and analyze ESPVR using the previously validated single-beat method.

Results: Intraoperative RV PV loops were generated for 25 patients, including 17 patients with preserved RV systolic function (group 1) and 8 patients with reduced systolic function (group 2). Mean E_es, E_a, and E_es/E_a ratio were 0.63 ± 0.25 mm Hg/mL, 0.60 ± 0.23 mm Hg/mL, and 1.0 8 ± 0.31 mm Hg/mL, respectively, by the P_max method and 0.56 ± 0.32 mm Hg/mL, 0.60 ± 0.23 mm Hg/mL, and 0.91 ± 0.21 mm Hg/mL, respectively, by the V₀ method. Group 1 had a significantly higher E_es compared to group 2 regardless of the calculation method and a larger E_es/E_a ratio calculated by the V₀ method.

Conclusions: It is clinically feasible to derive RV PV loops from routine hemodynamic and echocardiographic data. With further validation and technological support, this can be a potential real-time intraoperative RV function monitoring tool.