HeartMate LVAD Provides Overall Improvements
A study published in the most recent issue of the New England Journal of Medicine evaluated the benefits of a new left ventricular assist device (LVAD), the HeartMate II. The study was funded in part by the device manufacturer, Thoratec Corporation but the authors independently analyzed data provided by the company.
The study was conducted to evaluate the benefits conferred from newer designs of LVADs for patients with refractory heart failure. Newer devices utilize a continuous flow pump design, whereas earlier models relied on pulse volume-displacement. The newer design is intended to address some of the limitations of the older models, such as the limited durability over the long term and the large pump size required.
Researchers followed 131 patients with end stage heart failure at a number of different institutions who were on the waiting list to receive a new heart. Each patient had a continuous-flow pump LVAD while waiting treatment.
The average age of the patient participants was 50. And the majority, three-quarters, were men. Almost sixty-six percent of patients had end stage heart failure secondary to a cause other than ischemic event. Over 40 percent of the patients had previously been treated with an intraaortic balloon pump.
Primary outcome measures for the study included the number of patients who underwent heart transplant, had recovery of cardiac function, or continued on mechanical support for cardiac function and were still transplant eligible. Outcomes were evaluated 180 days following LVAD placement.
Patients used the device for a mean of 126 days. The range expanded considerably, from 1 to 600 days. Survival of the participants was 75 percent at six months and 68 percent at one year. Findings at three months indicated a significant improvement in cardiac function and quality of life.
Adverse effects were noted with the device, including two episodes of pump thrombosis. Additional effects included right heart failure, postoperative bleeding, stroke, and percutaneous lead infection. Twenty five patient deaths occurred before the six month endpoint, 18 of those patients died before being discharged from the hospitalization following LVAD implantation.
The team concluded that these devices offer support for patients with end stage heart failure. The device conferred benefits to patients, allowing other organs to recover by providing blood flow. Improvements to renal and hepatic function were particularly noted. Heart function also improved. In one patient, cardaic improvement was so marked that the patient no longer required a heart transplant.
As mentioned above, the newer devices have a smaller profile. The HeartMate II has been described as the size of a D-cell battery. This size makes the device appropriate for implantation in a wider variety of patients, as the device needs to be able to fit within the chest cavity. Children, including teenagers, and some women would not be eligible for treatment with the other devices.
Other advantages of the next generation of LVADs include a quieter profile and a smaller tube that connects the LVAD to a battery pack worn externally and the device controller. An additional benefit is that the device appears to be superior to those products already on the market. As well, the device can be used to assist patients who are not eligible to undergo cardiac transplantation and may be appropriate for long-term treatment.
Early findings were presented at the spring meeting of the American College of Cardiology, which were described on Hospital Buyer.
August 31, 2007 Related topics: Quality, Safety, Errors, Cardiology