Hydrodynamic properties of a new percutaneous intra-aortic axial flow pump

Cardiac intervention, myocardial infarction, or postoperative heart failure will sometimes create a need for circulatory support. For this purpose, a new, minimally invasive intraaortic cardiac support system with a foldable propeller has been developed. In animals, the pump has been shown to have a positive hemodynamic influence, and the present study evaluates the hydrau lic properties of the pump in a bench test. The axial flow pump is a cathet er system with a distal motor driven foldable propeller (0 -15,000 revoluti ons per minute). To protect the aortic wall, filaments forming a cage surro und the propeller. In the present study, tests were done with two different pumps, one with and one without the cage. Two different models were used, one for testing pressure generation and one for obtaining flow-pressure cha racteristics. Propellers and tubes with different diameters were studied, a nd pressure and flow characteristics were measured. The mathematical relati onships between pressure and rotational speed, pressure, and diameter of pr opeller and tube were determined. There was a positive relationship between the revolutions per minute and the generated pressure, a positive relation ship between the diameter of the propeller and pressure, and a negative rel ationship between the diameter of the tube and the generated pressure. With in the physiologic range of cardiac output, there was a small drop in press ure with increasing flow in the tubes with a small diameter. With an increa sing diameter of the tube, a smaller pressure drop was seen with increasing flow. The present cardiac support system has hydraulic properties, which m ay be of clinical relevance for patients with left ventricular heart failur e.