Hemodynamic properties of the hemopump HP14

Background. The Hemopump HP14 is a catheter-mounted, transvalvular, left ve ntricular assist device intended for femoral percutaneous insertion. The pu mp was developed for patients with postoperative or postinterventional low cardiac output and for CABG surgery on the beating heart. Little is known a bout the effect of afterload and hematocrit on the pump performance. Methods. The influence of hematocrit and afterload on the pump flow was tes ted using an in vitro model filled with heparinized bovine blood. Regressio n analysis of the pump flow with respect to three hematocrit values (20%, 3 0%, 40%) and ten afterload levels (30 mmHg-120 mmHg in 10 mmHg increments) was performed for all pump speed levels (n = 7). Results. At all pump speed levels reduction of afterload and hematocrit wer e significant predictors for increasing pump flow (p<0.001). For hematocrit values between 40% and 20% and highest pump speed, mean pump flow at lowes t afterload ranged between 2.34 and 2.53 L/min; and at highest afterload be tween 1.31 and 1.53 L/min. For speed level I, afterload of 120 mmHg and hem atocrit of 40% there was a maximal retrograde flow of 230 +/- 35 ml/min. Conclusions. Pump performance is significantly improved by both afterload a nd hematocrit reduction. In the weaning phase and during the removal of the device, the primp should run at a speed level of at least three to prevent retrograde flow in the pump. Estimates for pump flow in vivo can be extrap olated from our diagrams. Our results show that the Hemopump HP14 is a valu able alternative to intra-aortic balloon counterpulsation.