Haemodynamic effects of vena cava occlusion at different occlusion ratios and sites: A mock circulatory loop study

The haemodynamic effects of vena cava occlusion are related to the patient's preserved cardiac function. Investigating the haemodynamic effects is critical for the clinical translation of vena cava occlusion devices.

A mock circulatory loop (MCL) system was developed for the in vitro haemodynamic simulation of the systemic venous system. Haemodynamic effects of vena cava occlusion were assessed under different heart failure states, different occlusion ratios and distinct occlusion sites.

Superior vena cava (SVC) occlusion significantly reduced both central venous pressure (CVP) and renal venous pressure (RVnP) while causing only a limited decrease in cardiac output (CO), however, jugular venous pressure (JVP) increased significantly. Inferior vena cava (IVC) occlusion below the right atrium caused negative CVP, a significant reduction in CO and increased RVnP. In contrast, IVC occlusion below the renal veins preserved CO while reducing RVnP and improving renal perfusion. Moreover, effective pressure gradients were observed at occlusion ratios of 82.3%-87.1% for SVC occlusion and IVC occlusion below the right atrium, compared with 94.5%-96.1% for IVC occlusion below the renal veins.

SVC occlusion and IVC occlusion below the renal veins reduce cardiac preload and increase renal venous (RVn) flow, without significantly reducing CO. However, compared with SVC occlusion, IVC occlusion below the renal veins requires a higher occlusion ratio and provides limited ventricular unloading. IVC occlusion below the right atrium is not recommended, as this would lead to a significant reduction in CO and have adverse effects on the circulatory system.