We Always Need a Pulse, or Do We?

Abstract

To the Editor:With great interest and enthusiasm, I read the recent articleby Miller [1] regarding the influence of pulsatile and non-pulsatile mechanical circulatory support on heart failurepatients. The author describes that “the clinical trials withcontinuous flow VADs, including both centrifugal and axialflow, have all shown equal, if not superior end-organ func-tion compared to the first generation of pulsatile flowpumps. Therefore, pulsatile blood flow is not important tonormal organ function, which is more dependent on meanarterial pressure”. For this conclusion, he refers to the datapublished by Lietz et al. [2].While I thank the author for his valuable review, it is amisrepresentation of the published literature. Lietz et al.clearly mention that they studied a total of 69 patients whounderwent HeartMate XVE LVAD implantation at the Uni-versity of Minnesota Medical Center from October 30, 2001through June 13, 2006. They excluded from their analysisrecipients of other types of HeartMate LVADs, NovacorLVADs,andaxial flowdevices,aswell asthose whorequiredbiventricular temporary support before device implantation.HeartMate XVE, a volume displacement pump, is a pulsatileventricular assist device. Thus, there is no comparison be-tween rotary blood pumps (axial and centrifugal) and firstgeneration of pulsatile flow pumps in their study.Although clinical studies have shown that renal, hepatic,and neurocognitive functions are maintained within anormal range for durations up to 15 months [3], insufficientdata exist to generalize it and further long-term studies arecrucial to assess the effect of reduced pulsatility on end-organ function. As controversy still remains on this issue,the development of pulsatile rotary blood pumps wouldprovide a unique opportunity for further research and com-parison [4–5].References