Continuous Flow: The Next Evolution in LVAD Therapy

Figure 1

Figure 1: Survival rates in two trials of LVADs as destination therapy. The curves labeled 2009 are those reported by Slaughter and colleagues in the December 2009 issue of The New England Journal of Medicine,7 and those labeled 2001 were reported for the REMATCH trial.5

A study published in The New England Journal of Medicine in December 2009 demonstrated that continuous-flow LVADs significantly improved the probability of stroke-free survival and decreased the probability of device failure at two years compared with a pulsatile-flow LVAD in patients with end-stage heart failure who were ineligible for transplantation.7 In addition, patients who received the continuous-flow device had an actuarial survival rate at two years of 58 percent versus 24 percent for patients who received the pulsatile-flow device (Figure 1).

The HeartMate II® (Thoratec Corporation, Pleasanton, Calif., U.S.), a smaller, continuous-flow LVAD, received FDA approval in January 2010 as destination therapy for patients with end-stage heart failure who are ineligible for transplantation (Figure 2).8 The HeartMate II uses an internal motor to pump blood continuously into the ascending aorta, providing up to 10 liters of cardiac output per minute. Due to its smaller size, the device has a larger potential patient population than previous-generation LVADs. In addition, the HeartMate II is designed to provide greater mechanical reliability than previously available devices because it contains only one moving part – the internal rotor.9 The Emory VAD destination therapy program has implanted more than 25 HeartMate II devices to date.

Figure 2

Figure 2: HeartMate II® LVAD; reprinted with permission from Thoratec Corporation.

More recently, HeartWare International (Framingham, MA) introduced the HeartWare LVAD system, which uses a continuous centrifugal pump to provide up to 10 liters of cardiac output per minute (Figure 3). Because the device is implanted above the diaphragm, directly adjacent to the heart, both surgery and recovery times are minimized.10

Like the HeartMate II, the HeartWare LVAD contains only one moving part – the internal impeller. In addition, it has no mechanical bearings or points of contact between the impeller and the pump housing in order to lower the risk of device failure and is designed to help minimize the risk of device-induced hemolysis and thrombus.10

Figure 3

Figure 3: HeartWare® LVAD; reprinted with permission from HeartWare International.

Already approved in Europe as a bridge to cardiac transplantation, the safety and efficacy of the HeartWare LVAD are currently under investigation in the U.S. in the ADVANCE trial, a crucial step toward securing FDA approval for the bridge-to-transplant indication.11 Emory University Hospital is one of approximately 30 registered ADVANCE trial sites and has implanted one device to date.