Invited Commentary

Abstract

Historically, mechanical assist devices were used as an emergency bridge to support patients until a suitable donor organ could be found [1Delgado D.H. Rao V. Ross H.J. Verma S. Smedira N. Mechanical circulatory assistance: state of art.Circulation. 2002; 106: 2046-2050Crossref PubMed Scopus (40) Google Scholar]. As such, a decade ago most devices were implanted for less than a year and were not designed to provide prolonged support. The presence of a valvular pathologic condition at the time of ventricular assist device (VAD) implantation dictated surgical strategy, and significant aortic insufficiency required intervention [2Rao V. Slater J.P. Edwards N.M. Naka Y. Oz M.C. Surgical management of valvular disease in patients requiring left ventricular assist device support.Ann Thorac Surg. 2001; 71: 1448-1453Abstract Full Text Full Text PDF PubMed Scopus (141) Google Scholar]. However, with increasing clinical experience and improved device technology, the concept of “destination” therapy became a reality, and prolonged support (>1 year) is now common. In many centers, including our own, the average support time, even in a bridge to transplantation population, exceeds 1 year. Often, clinical success breeds novel problems, and “acquired aortic insufficiency” (AI) has now become accepted among heart failure specialists. This report [2Rao V. Slater J.P. Edwards N.M. Naka Y. Oz M.C. Surgical management of valvular disease in patients requiring left ventricular assist device support.Ann Thorac Surg. 2001; 71: 1448-1453Abstract Full Text Full Text PDF PubMed Scopus (141) Google Scholar] from Advocate Christ Medical Center, a leading enroller in the Destination Therapy (DT) trial, describes their experience with almost 80 patients supported by a HeartMate 2 device. During their period of follow-up, over half of their patients experienced significant AI (defined as mild or greater). Of interest, advanced age and a closed aortic valve were found to be independent predictors of AI progression. Strikingly, the mean time to AI development was just over 6 months in this cohort of predominantly DT patients (69 of 79). Surprisingly, despite the finding that a closed aortic valve was associated with AI, there were no significant differences in pump speeds between the patients who experienced AI and those with a competent valve. Thus, the clinician remains somewhat confused over formulating a strategy to militate against AI. We have found that maintaining low pump speeds (8600 rpm vs the mean of 9200 rpm in this series) allows the aortic valve to open intermittently. We intentionally “ramp down” pump speeds at early follow-up (1 to 3 months) to achieve aortic valve opening every three cardiac cycles. Although we initially used this strategy to preserve the aortic valve, we have, surprisingly, found a dramatic decrease in the incidence of gastrointestinal bleeding (data published in abstract form). We have insufficient follow-up time to determine whether this strategy will lead to long-term aortic valve competence. Other clinicians have advocated for either formal aortic valve closure or a repair suture to maintain long-term aortic valve competence [3Aggarwal A. Raghuvir R. Eryazici P. et al.The development of aortic insufficiency in continuous-flow left ventricular assist device-supported patients.Ann Thorac Surg. 2013; 95: 493-499Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar, 4Park S.J. Liao K.K. Segurola R. Madhu K.P. Miller L.W. Management of aortic insufficiency in patients with left ventricular assist devices: a simple coaptation stitch method (Park's stitch).J Thorac Cardiovasc Surg. 2004; 127: 264-266Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar]. However, the impact of a permanently fused aortic valve on long-term clinical outcomes (especially gastrointestinal bleeding) has not been determined. The importance of the present report is to emphasize that aortic valve competence becomes an issue as early as 6 months after implantation, even in patients who had no aortic insufficiency at the time of VAD implantation. The long-term sequelae of either permanently fusing the aortic valve or lowering VAD support to facilitate intermittent aortic valve opening remains unknown and again will require vigilant clinical follow-up. The Development of Aortic Insufficiency in Continuous-Flow Left Ventricular Assist Device–Supported PatientsThe Annals of Thoracic SurgeryVol. 95Issue 2PreviewSignificant aortic insufficiency (AI) after left ventricular assist device (LVAD) placement affects device performance and end-organ perfusion. This study examined the development and progression of AI after implantation of continuous-flow LVAD. Full-Text PDF