Cardiac Assist Devices: Early Concepts, Current Technologies, and Future Innovations

Abstract

Congestive heart failure (CHF) is a debilitating condition that afflicts tens of millions of people worldwide and is responsible for more deaths each year than all cancers combined. Because donor hearts for transplantation are in short supply, a safe and durable means of mechanical circulatory support could extend the lives and reduce the suffering of millions. But while the profusion of blood pumps available to clinicians in 2019 tend to work extremely well in the short term (hours to weeks/months), every long-term cardiac assist device on the market today is limited by the same two problems: infections caused by percutaneous drivelines and thrombotic events associated with the use of blood-contacting surfaces. A fundamental change in device design is needed to address both these problems and ultimately make a device that can support the heart indefinitely. Toward that end, several groups are currently developing devices without blood-contacting surfaces and/or extracorporeal power sources with the aim of providing a safe, tether-free means to support the failing heart over extended periods of time.

Keywords: LVAD; cardiac assist devices; congestive heart failure; destination therapy.

Figure 1

The first generation pulsatile-flow pumps (A) replicated the native cardiac cycle using a diaphragm and unidirectional artificial heart valves, while the second generation continuous-flow pumps (B) integrated a valveless axial pump designed to rapidly spin a single impeller.

Figure 2

Timeline of important milestones of cardiac assist device (CAD) development history [38,39].

Figure 3

Examples of first, second, and third generation cardiac assist devices [40,41,42,43,44,45,46].

Figure 4

ECMO (A), AbioMed Impella (B), Teleflex Arrow IABP (C), and Thoratec CentriMag (D) are examples of temporary support mechanisms commonly used in clinical settings today [64,65,66,67].

Figure 5

Some of the most longstanding complications after left ventricular assist device (LVAD) implantations are driveline infections (A), pump thrombosis (B), and gastrointestinal bleeding (C) [83,84,85].

Figure 6

Schematics of the TET system (A) in patient use and (B) with an electromagnetic coupling between the internal and external coils located inside and outside of patient skin, respectively [100,101].

Figure 7

Muscle-powered VADs could use the latissimus dorsi (A) as its power source and convert this endogenous muscular power into hydraulic energy via a completely implantable muscle energy converter (B) that can potentially power pulsatile VADs for long-term use (C) [103,106,107].

Figure 8

Biomimetic (A), minimally invasive (B), and muscle-powered (C) soft robotic direct cardiac compressive sleeves (DCCS) use copulsation and extra-aortic balloon pumps (EABP) (D) use counterpulsation techniques to enhance cardiac function without directly interacting with the bloodstream [107,108,113,114,117].