ID:18 OA2-6 Increased Right Ventricular End-Diastolic Volume During Pump-Controlled Retrograde Trial Off Varies by Cardiac Failure Model: A Mock Circulatory Loop Study

Background: Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is an established rescue therapy for refractory cardiogenic shock; however, standardized weaning assessment remains lacking. Pump-controlled retrograde trial off (PCRTO), initially developed in paediatric practice, has recently been applied in adult V-A ECMO, but its underlying physiology is incompletely understood. By creating an arterio–venous shunt, PCRTO is expected to increase right ventricular end-diastolic volume (RVEDV). This study aimed to quantify changes in RVEDV across different cardiac failure models and ECMO flow settings during simulated weaning conditions using pressure–volume loop analysis. Methods: Using a validated mock circulatory loop, we simulated: 1) normal cardiac function, 2) a left ventricular failure (LVF) model, and 3) a right ventricular failure (RVF) model characterized by reduced right ventricular end-systolic elastance and elevated pulmonary vascular resistance. The ECMO drainage cannula was placed in the systemic venous compartment, and the return cannula was placed in the aortic chamber. RVEDV and its changes were compared across cardiac models under different ECMO flow settings: 1.0 L/min (baseline), 0.5 L/min, 0 L/min, and -0.5 L/min (PCRTO). Results: Overall, reductions in ECMO flow were associated with increases in RVEDV. At PCRTO (-0.5 L/min), RVEDV increased by 5.4% in the LVF model and 3.5% in the normal model compared with baseline flow. In contrast, the magnitude of RVEDV increase was greatest in the RVF model, with an 8.2% increase at PCRTO. Conclusion: PCRTO increased RVEDV, particularly in the presence of right ventricular failure, indicating that the degree of preload increase induced by PCRTO depends on underlying cardiac function. Further in vivo studies are required to validate these findings.