Alternation of left ventricular load by a continuous-flow left ventricular assist device with a native heart load control system in a chronic heart failure model.

OBJECTIVE

We previously developed a native heart load control system for a continuous-flow left ventricular assist device and demonstrated that the rotational speed synchronized with the cardiac cycle can alter left ventricular preload and myocardial oxygen consumption. In the present study, we assessed this system in a conscious goat model of chronic heart failure.

METHODS

Chronic heart failure was induced by coronary microsphere embolization of the left ascending artery and subsequent rapid ventricular pacing in 6 goats. After 4 to 6 weeks of rapid pacing, the goats showed a decreased ejection fraction (from 89.7% ± 3.1% to 53.3% ± 5.4%) measured during sinus rhythm. The assist device was implanted by way of a left thoracotomy, and we examined the effects of the continuous, co-pulse, and counterpulse mode on the end-diastolic volume and stroke work, determined from the left ventricular pressure-volume loops.

RESULTS

Significant decreases were found in the end-diastolic volume and stroke work in the counterpulse mode relative to the values observed with 0% bypass (63.4% ± 15.2% and 39.1% ± 18.2%, respectively; P < .01). Furthermore, both increased in the co-pulse mode (82.1% ± 17.6% and 68.3% ± 22.2%; P < .01) compared with those in the continuous mode (69.6% ± 15.4% and 54.6% ± 21.6%) with 100% bypass.

CONCLUSIONS

The system offers the possibility to control the left ventricular load by changing the rotational speed of a continuous-flow assist device in synchronization with the cardiac cycle. This system should provide the most favorable left ventricular loading conditions for recovery of the native heart.