Achieving adequate blood flow during Cardiopulmonary bypass (CPB) through peripheral vessel cannulation for minimally invasive heart surgery can be hazardous. Usually, a goal-directed therapy in CPB conditions with flow restriction, an optimal tissue oxygen balance can be obtained by adaptation of the level of hemodilution, and/or improving the venous drainage as being the most critical component in minimally access cardiac surgery. Hereto, the choice of the best venous cannula, both in terms of design as in size, becomes crucial, to cope with the eventual adaptive measures to improve the venous drainage like the application of negative pressure-assisted venous suction. Whereas mathematical modeling has been done for assessing the hemodynamic performance of arterial cannulas, this has not been done for venous cannulas.

In this research project, the hemodynamic performance of commercially available venous cannulas will be explored in an ex-vivo experimental set-up, and compared to real-life findings based on in-vivo measurements from surgical procedures in cardiac patients.

1. An in-vitro model is build based on a 3D-reconstruction of the human central venous system, consisting of the superior caval vein, the right atrial cavity, the inferior caval vein to the iliac veins, including all major side-branches of the coeliac and renal organs. The hemodynamic performance of various venous cannulas with different design and size are then compared in standardized conditions for filling fluid pressure and flow, and stepwise increase of negative suction venous drainage. This experiment is expected to identify the optimal design and size of the venous canula, as well as to identify the hemodynamic conditions promoting venous collapse and/or gaseous bubble formation due to cavitation.

2. The performance of venous cannulas, actually used for minimally invasive heart surgery procedures, is recorded in a clinical perfusion database, with real-time registration of pressure and flow rate variability during the procedure. The in-vivo measured data are compared with the mathematically predicted values - based on in-vitro measurements - to identify the hemodynamic factors predisposing to flow restrictions during CPB and to the occurrence of venous suction events.

The findings of this research might open a perspective to revise/optimize eventually the design of the venous cannula used for minimally invasive heart surgery through peripheral vessel access.