The discrepancy between donor organ availability and the number of patients with end-stage heart failure requiring transplantation led to the development of implantable mechanical devices that temporarily sustain ventricular systolic function. The devices currently available sustain left ventricular function by generating pulsatile or continuous flow, or biventricular systolic function by generating pulsatile flow. The original aim was to develop a totally implantable device that replaced the need for an allograft. However, current ventricular assist devices (VAD) are approved only as a bridge to heart transplantation in patients unable to wait for a suitable allograft due to the severity of their symptoms. They are thus an option in patients with severe systolic dysfunction, in New York Heart Association functional classes III-IV with recent rapid deterioration.
There are three main scenarios of VAD implantation:
Elective: to prevent end-organ dysfunction in transplant candidates with progressively deteriorating heart failure.
Urgent: patients with rapidly worsening cardiovascular function and multiorgan repercussions requiring immediate measures such as ventilation or hemofiltration.
Emergency: patients developing cardiogenic shock in a setting of acute myocardial infarction, myocarditis, or surgery, who are unresponsive to conventional medical therapy, and are potential transplant candidates requiring an immediate bridging procedure.
Recent data indicate that VAD is a therapeutic tool that not only sustains ventricular systolic function, but may also reverse the pathophysiologic changes induced by the heart failure syndrome, such as renin-angiotensin-aldosterone system hyperactivation, myocardial remodeling, and apoptosis. Responders may tolerate removal of the device and a further delay before transplantation. However, although VAD is a valid option in these patients with severe decompensation and low cardiac output, its widespread use is limited by the complications of infection, thromboembolism, and hemorrhage.
Ongoing research is testing totally implantable artificial hearts. The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart failure (REMATCH) showed that VAD implantation was an effective permanent support solution in end-stage patients in a transplant program requiring continuous inotropic drug administration. The population was the most severely diseased ever entered in a randomized trial (only 8% of the controls survived 2 years) and VAD implantation decreased 1-year mortality by 48%. Infection and thromboembolism were the major limitations to survival.
management; end-stage heart failure; ventricular assist device; indication; trial
When should a ventricular assist device be considered? Photo Gallery
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