Hemodynamic effects of a new percutaneous circulatory support device in a left ventricular failure model

We have tested a new percutaneous circulatory support device in seven anesthetized calves with induced left ventricular failure. The device is based on a flexible catheter with a foldable propeller and cage at the distal end. The rotation of the propeller (1,000-15,000 rpm) is transmitted from a drive unit at the proximal end to the propeller by way of a rotating wire inside the catheter. This also contains an umbrella-like mechanism to open the pump head from the folded (diameter 4.6 mm) to the active position. The rotation of the propeller creates a pressure drop in front of the propeller and a pressure rise behind. Heart failure was induced with metoprolol and verapamil in combination with a VVI pacemaker to create a left atrial pressure greater than 20 mm Hg. A centrifugal pump was used to bypass the right ventricle and to ensure a sufficient filling of the left ventricle. After baseline recordings, the pump was run at 14,000 rpm, and the hemodynamic response was compared with the baseline. A 24 +/- 10 mm Hg pressure gradient was generated across the pump, resulting in a drop in the right carotid artery mean pressure from 80 +/- 11 to 71 +/- 13 mm Hg (p = 0.008) and a drop in the left ventricular systolic pressure from 109 +/- 17 to 100 +/- 19 mm Hg (p = 0.004). The pressure in the left atrium decreased from 25 +/- 3 to 20 +/- 5 mm Hg (p = 0.008). The mean femoral pressure increased from 78 +/- 10 to 95 +/- 20 mm Hg (p = 0.005). A moderate reduction in the right carotid flow was observed (15%, p = 0.029), whereas no significant changes were found in the coronary flow, the flow in the right femoral artery, or in the left kidney. The device showed a significant unloading of the left ventricle and an increased perfusion pressure for the lower part of the body. The moderate changes in flow were probably caused by still active autoregulation, and this needs to be tested with more pronounced circulatory failure.