Mechanical Circulatory Support
Registering a Therapy in Evolution
Received March 26, 2008; accepted June 5, 2008.
The development of durable mechanical circulatory support systems paralleled the expansion of cardiac transplantation. The National Institutes of Health sponsored grants in the 1980s to develop implantable left heart assist systems; 20 years later, they contracted for a national registry, the Interagency Registry for Mechanical Assisted Circulatory Support, to track the clinical evolution of this new technology. The Interagency Registry for Mechanical Assisted Circulatory Support has refined the classification of New York Heart Association class IV heart failure, standardized adverse event definitions, and explored outcomes of device type, location, and strategy. The majority of mechanical circulatory support patients are between the ages of 50 and 70 years, and ≈90% of patients are in the highest levels of clinical instability before implantation. Six-month survival after device implant is 75%, but it increases to 80% among those not in shock at implantation. Patients who require biventricular support have decreased survival. As longer-term outcomes are analyzed, improved outcomes may justify triage of high-risk patients awaiting heart transplantation to chronic mechanical circulatory support.
Developmental History of Mechanical Circulatory Support
The application of mechanical circulatory support in animal experiments can be traced back to the work of Carrel and Lindberg in the 1930s.1,2 With the initial foray into open-heart surgery in the 1950s,3,4 the stage was set for application of more prolonged mechanical support for myocardial recovery in situations of failure to wean from cardiopulmonary bypass. Although initial reports of successful recovery used roller-pump technology,5 their applicability was limited by issues of blood trauma and difficulties in modulation of pump speed in response to changes in left atrial and left ventricular pressure. The first clinical application of a pneumatically driven ventricular assist device (VAD) is attributed to DeBakey in 1966, in which a 37-year-old woman was successfully supported for 10 …