Honoring 50 Years of Clinical Heart Transplantation in Circulation: In-Depth State-of-the-Art Review

Josef Stehlik, MD, MPH; Jon Kobashigawa, MD; Sharon A. Hunt, MD; Hermann Reichenspurner, MD, PhD; James K. Kirklin, MD

Disclosures

Circulation. 2018;137(1):71-87. 

In This Article

Mechanical Circulatory Assist in the Context of Heart Transplantation

MCS devices have had a major impact on the field of heart transplantation. Durable bridge-to-transplantation (BTT) devices include total artificial heart and ventricular assist devices. A number of temporary mechanical support devices are also used as BTT.

Total Artificial Heart

The first total artificial heart as a BTT was performed by Dr Cooley in Houston in 1969. The patient underwent orthotopic heart transplantation 2 days later but died after 32 hours of renal failure and pneumonia.[77] In 1982, DeVries at the University of Utah implanted the first total artificial heart (Jarvik 7) intended as permanent therapy.[78] This device, now called the SynCardia total artificial heart (SynCardia, Tucson, AZ), has since received approval from the US Food and Drug Administration for BTT use. The leading indication for its use today is severe biventricular failure not amenable to partial mechanical support of the left ventricle.

Ventricular Assist Devices

The original goal of a partial artificial replacement heart, later known as LVAD, was to aid recovery of the heart after complex cardiac surgery.[73] In 1966, DeBakey first used an LVAD in a patient unable to wean from cardiopulmonary bypass after valve surgery.[79] In the 1970s, Portner and Oyer at Stanford University developed an electric dual pusher-plate Novacor LVAD (World Heart Corp, Oakland, CA), resulting in the first long-term survival of a patient with an LVAD[80] and successful clinical use as BTT therapy.[81] Subsequently, the HeartMate I (Thoratec Corp, Pleasanton, CA) intracorporeal pulsatile pump became the first device approved for long-term destination therapy.[77]

Current generations of LVADs use predominantly continuous-flow technology, which allows a marked reduction of device size and a reduction or elimination of moving components such as valves and bearings. This has in turn resulted in improved pump durability (some patients now remain on LVADs for many years), increased patient survival, and reduction of complications. A number of devices have received US Food and Drug Administration approval for use as BTT (HeartMate II [Thoratec Corp, later Abbott, Abbott Park, IL], HVAD [Heartware Inc, FL, later Medtronic, Minneapolis, MN]), and others are undergoing clinical testing (Jarvik2000 [Jarvik Heart Inc, New York, NY], HeartMate3).[82–84] BTT approach with the current-generation devices leads to 6-month survival in the range of 80% to 90% and to a low risk of mortality on the transplantation waiting list (Figure 7).[85]

Figure 7.

Waiting list survival of heart transplantation candidates registered on the United Network of Organ Sharing (UNOS) waiting list in 2008 to 2011.
UNOS status 1A, 1B, and 2: candidates without mechanical circulatory support listed in high, intermediate, and low urgency status, respectively. CF-LVAD indicates continuousflow left ventricular assist device. Adapted from Wever-Pinzon et al85 with permission. Copyright ©2013, American Heart Association, Inc.

Another advantage of axial-flow or centrifugal pumps is the possibility of less invasive implantation; the pump itself is implanted via a small left anterolateral thoracotomy, possibly reducing the risk of complications associated with a full resternotomy at the time of transplantation.[86]

Important post-LVAD adverse events include stroke, infection, gastrointestinal bleeding, and device thrombosis. Future technology improvements are focused on increased biocompatibility of the materials, further miniaturization, artificially generated pulsatility, and conversion to totally implantable systems.

Temporary Circulatory Support

Temporary circulatory support is increasingly applied to patients in cardiogenic shock awaiting or considered for transplantation. Venoarterial extracorporeal membrane oxygenation is a frequently used support system that allows transportation of patients in shock to tertiary heart failure centers. Percutaneous axial flow left ventricular support devices (eg, Impella; Abiomed Inc, Danvers, MA) can be inserted through the femoral or subclavian artery (via surgical access) and provide support to the left ventricle, propelling up to 5 L of blood per minute from the left ventricle into the aorta. Surgically implanted extracorporeal pumps (eg, CentriMag, Abbott) can also be used in the LVAD or right VAD configuration. Despite adequate hemodynamic support, survival after transplantation in patients with temporary circulatory support is often inferior to that of other patient cohorts.

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....