The Need of Slanted Side Holes for Venous Cannulae

Well-designed cannulae must allow good flow rate and minimize nonphysiologic load. Venous cannulae generally have side holes to prevent the rupture of blood vessel during perfusion. Optimizing side hole angle will yield more efficient and safe venous cannulae. A numerical modeling was used to study the effect of the angle (0°-45°) and number (0-12) of side holes on the performance of cannulae. By only slanting the side holes, it increases the flow rate up to 6% (in our models). In addition, it was found that increasing the number of side holes reduces the shear rate up to 12% (in our models). A new parameter called "penetration depth" was introduced to describe the interfering effect of stream jets from side holes, and the result showed that the 45°-slanted side holes caused minimum interfering for the flow in cannula. Our quantitative hemodynamic analysis study provides important guidelines for venous cannulae design.