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Ann Thorac Surg 2006;82:1418-1419
© 2006 The Society of Thoracic Surgeons
Division of Cardiothoracic Surgery, University of North Carolina at Chapel Hill, 3040 Burnett Womack, CB 7065, Chapel Hill, NC 27599
(Email: selzman{at}med.unc.edu).
The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) trial investigating lifetime use of left ventricular assist devices (LVAD) in non-transplant-eligible patients with end-stage heart disease was performed between 1998 and 2001 using the HeartMate vented electric (VE) device (Thoratec Corp, Pleasanton, CA). This seminal study rigorously and prospectively established new standards for survival, quality of life, and adverse events in this severely ill patient population.
Despite the favorable results for LVAD versus optimal medical management, REMATCH is often criticized by the medical community: few patients survived more than 2 years secondary to high rates of adverse events (infection, bleeding, neurologic) and device failure (35% at 2 years). As reported by other investigators, thorough infection prophylaxis, careful anticoagulation protocols, and increased surgical experience have markedly reduced adverse events and have improved survival. The Achilles' heel of lifetime LVAD therapy ultimately rests on the latter point of device durability.
The current article reports the impact of changes in technology on device malfunction. Pagani and colleagues [1], from four active LVAD centers, compared their results using the HeartMate VE, which was used in REMATCH, versus the two latest perturbations in the HeartMate XVE pump. These changes include a new inflow valve housing (this accounted for more than 50% of REMATCH device failures), new software for the controller to optimize filling pressure–volume relationships, a slicker percutaneous lead, outflow graft bend relief, and locking screw rings to secure the pump, valves, and grafts. The results show the marked decrease in major device malfunctions with the XVE, including bearing failures (likely from the software improvements), inflow and outflow valve dysfunction, and diaphragm rupture.
Although this report clearly demonstrates a decrease in mechanical problems in the latest HeartMate pump, the data need to be viewed with some circumspection. Most of the devices (82%) were used for bridging to transplantation. As such, long-term reliability remains unknown. In fact, fewer than 30% of the devices were implanted for more than 1 year and fewer than 5% of XVE pumps were still implanted at 18 months. It is not clear how many pumps, if any, were replaced secondary to their malfunctions (with the attendant morbidity and mortality) or if pump failure became the indication for transplantation. Because of the limitations of numbers with extended follow-up, it is difficult to extrapolate how the latest structural and software changes can influence long-term survival.
With the increasing number of pulsatile and continuous pumps either in use or in development, it is clear that we have good solutions for bridging patients with mechanical support. The challenge of an efficient, safe, and durable LVAD for lifetime use still exists. Although there are patients with Novacor and Jarvik 2000 LVADs with their original pump 5 years later, this level of durability has not been observed with the HeartMate pumps.
The current authors should be commended for their ongoing review of their clinical experience and implementing changes to improve reliability and outcomes. Contemporary reports such as these are important, over time, to say that device therapy, like medical therapy, is a moving target.
The current HeartMate XVE is better than the outdated pump of REMATCH. With continued refinement of existing pumps as well as the development of new, innovative devices, short-term and long-term results will continue to improve. Only then will LVAD therapy overcome the current culture of reluctance and become more acceptable to our patients and referring physicians.
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