In the case of open-heart surgery, an external blood pump maintains the circulatory pressure. Venous blood is collected, oxygenated, and pumped into the body through an aortic cannula. The so-called cardiopulmonary bypass (CPB) is related to complications like stroke or hypoxia. The aortic cannula jet is suspected to be one reason for these complications, due to the sandblast effect on the vessel wall. Several in silico and in vitro studies investigated the underlying mechanisms, but the applied experimental flow measurement techniques were not able to address the highly three-dimensional flow character with a satisfying resolution. In this work, in vitro scanning stereoPIV measurements in a cannulated and a non-cannulated aortic silicone were performed to investigate cannula flow.