Unforeseen Consequences of Therapy With Continuous-Flow Pumps

Abstract

H amlet's statement may well be applied to the marked alteration in normal mammalian physiology introduced by the use of left ventricular assist devices (LVADs), particularly the nonpulsatile devices. This alteration of the "stamp of nature" has led to changes in the normal circulatory physiology not previously encountered in the field of medicine. Two unanticipated consequences of the clinical application of LVAD technology-acquired aortic valve insufficiency (AI) and acquired von Willebrand syndrome (VWS)-are reported in this issue of Circulation: Heart Failure. Articles see pp 668 and 675The report by Cowger et al 1 quantifies a single-center experience with acquired AI after implantation of both the pulsatile HeartMate XVE (HM-XVE) and the nonpulsatile HeartMate II (HM-II) LVAD (Thoratec Corporation, Pleasanton, Calif). These investigators used echocardiography to study 78 patients who received the HeartMate XVE (nϭ25) or HeartMate II (nϭ53) LVAD between 2004 and 2008. They performed 315 studies at set time intervals and graded AI and aortic valve opening according to classic echocardiographic methodology. Trends in the development of AI were assessed in the group as a whole and were then compared by device type. Because this was a single-center study, the numbers available for follow-up evaluation were limited (49 patients at 6 months, 29 patients at 12 months, 13 patients at 18 months, and 5 patients at 24 months). However, an increase in both the development and the severity of AI was noted during this period. The grade of moderate-to-severe AI was approximately 11% at 6 months, 26% at 12 months, and 51% at 18 months. Compared with patients with the HM-XVE device, those with the HM-II pump had an increased incidence and severity of AI; however, in no patient was the AI severe enough to require intervention. The authors proposed several possibilities as to the cause of the AI but made no substantive conclusions about the etiology other than the presence of the device.Development of AI in HM-XVE recipients was first noted clinically both in the bridge-to-transplant population and the REMATCH trial. 2 Although not of critical clinical importance, the regurgitation could cause accelerated pump flow and further contribute to the already limited durability of these pumps. In the wake of these clinical observations, we attempted to quantify our experience with aortic valve deformity in HM-XVE recipients by analyzing 33 cases in which autopsy specimens or post-transplant explants were available. In 17 of these cases, we found some degree of aortic cusp fusion. 3 Sixteen of the HM-XVE patients and only 1 of the HeartMate pneumatic (HM-IP) pump patients had cusp fusion. The implantable pneumatic HeartMate required venting every 24 hours; this ensured native aortic valve opening during the short (8-second) venting period. This minimal opening of the native aortic valve interrupted commissural fusion and protected against the development of AI. 4 Aortic valve opening temporarily interrupts the stress of systolic pres...

Trends in the Use and Outcomes of Ventricular Assist Devices Among Medicare Beneficiaries, 2006 Through 2011

“…However, VAD care is further complicated by multiple other problems, including caregiver burden and limited hospital infrastructure to manage patients with minimally pulsatile circulation. Further, there is a continually evolving knowledge base on the impact of nonpulsatile blood flow on circulation and the utility of existing therapeutics for common adverse events encountered during VAD support (32). We postulate that the required elements of this accruing provider knowledge base, psychosocial support, and healthcare infrastructure are likely to be concentrated at larger centers implanting a large number of VADs.…”

De Novo Aortic Regurgitation After Continuous-Flow Left Ventricular Assist Device Implantation

“…Continuous-flow devices have successfully challenged the pulsatile rheologic dogma. However, some adverse events unique to nonpulsatile flow have become evident [27,28]. De novo AR is among these.…”

Mathematical analysis of the effects of valvular regurgitation on the pumping efficacy of continuous and pulsatile left ventricular assist devices

“…LVAD is normally contraindicated in significant aortic regurgitation (AR) and requires intraoperative valve repair or exclusion 7, 8. Furthermore, LVAD aggravates preexisting AR 9, 10. Nevertheless, AR can coexist with LVAD, 11 so a valid question when asked might still be of clinical significance.…”