Heart failure (HF) is a leading cause of death in the United States and a significant public health concern throughout the world. Results from the Framingham Heart Study suggest that the lifetime risk of developing HF for Americans over the age of 40 years is approximately 20%, and the incidence of this disease steadily increases with age.1 An estimated 5.1 million Americans are living with HF. This figure is expected to grow significantly in the coming decades because the average age of the population is increasing, and advancements in medical therapy are allowing patients to live longer with their disease.2,3 The economic burden of disease is also high, and total healthcare costs attributed to HF exceed $30 billion in the United States each year.2,3 In light of the increased mortality associated with HF, strategies for managing this disease have grown increasingly sophisticated.
Treatment of advanced HF is based on three principal methodologies: medical therapy, corrective surgical intervention, and cardiac support or replacement. Appropriate medical management with antihypertensive, diuretic, vasoactive, and inotropic therapy has been shown to improve symptoms, slow the progression of disease, and (in some cases) provide survival benefits.4 Patients with more severe disease may benefit from specific surgical interventions such as coronary revascularization, valve replacement or repair, and ventricular restoration procedures.5,6 These procedures often pose a high risk, and surgical candidacy is typically assessed on a case-by-case basis.
Selected patients with severe HF refractory to guideline-directed medical therapy may ultimately be considered candidates for cardiac transplantation or mechanical circulatory support (MCS). Because of a relative scarcity of available donor organs for transplantation, device therapy has become an increasingly popular option for managing end-stage HF and offers documented survival benefits over medical therapy alone.7 Whereas only 33 centers participated in the original clinical investigation (completed in 2009) of the HeartMate II left ventricular assist device (LVAD) (Thoratec, Inc., Pleasanton, CA), a total of 145 centers are now approved for device therapy in the United States. This number will likely continue to grow as this technology and other new MCS systems become more widely accessible.8,9
MCS is an inclusive term that refers to any device used to assist or replace the failing heart. The options are wide-ranging and include differences in pump location (implantable vs extracorporeal), support capabilities (left, right, or biventricular), and flow characteristics (pulsatile vs continuous). This chapter will focus primarily on the available long-term options for MCS, particularly current LVADs and the total artificial heart (TAH). Although MCS is not without inherent risks, rapid advancements in technology—paired with the practical limitations of transplantation—suggest that device therapy has an important role in both the present and the future of HF surgery.
HISTORY OF MECHANICAL CIRCULATORY SUPPORT
Open heart surgery was made possible by the pioneering efforts of ...