- Mechanical circulatory support (MCS) has evolved from a rarely used therapy reserved for the most critically ill hospitalized patients to an accepted long-term outpatient therapy for treating patients with advanced heart failure.
- Cardiac arrest in patients on mechanical support is a new phenomenon brought about by the increased use of this therapy in patients with end-stage heart failure.
- Because of the unique characteristics of mechanical support, these patients have physical findings that cannot be interpreted the same as for patients without MCS.
- For example, stable patients supported by a durable, continuous-flow ventricular assist device (VAD) often do not have a palpable pulse.
- Long-term MCS devices suitable for nonhospitalized patients are placed largely for 1 of 2 indications. These 2 designations are fluid. Patients can have their status changed from bridge to transplantation to destination therapy or vice versa on the basis of clinical changes.
- Bridge to transplantation refers to patients awaiting heart transplantation whose heart failure progresses despite medical therapy. In such cases, MCS is used as a bridge until a donor organ becomes available.
- Destination therapy refers to patients with advanced systolic heart failure who are not candidates for transplantation because of factors such as comorbidities or advanced age.
Note: In this population, MCS is the destination itself, as opposed to transplantation, and patients will typically live the remainder of their lives on mechanical support. This population is growing rapidly, with some patients being supported for many years.
- MCS can support function of the left ventricle (LV) with a left VAD (LVAD), the right ventricle (RV) with a right VAD (RVAD), or both ventricles with a biventricular assist device. A total artificial heart (TAH) replaces the heart itself.
Figure 1. Ventricular Assist Device (VAD) Configurations
Cartoon illustrating graphically the support intended with a left VAD (A), right VAD (B), or biventricular assist device (C).
Figure 2. Intracorporeal Pumps
Left figure is reproduced with permission from HeartWare.
Right figure (HeartMate II LVAD External Equipment Pocket Controller) is reproduced with permission of St. Jude Medical, copyright © 2016. All rights reserved. HeartMate, Pocket Controller, and St. Jude Medical are trademarks of St. Jude Medical, Inc. or its related companies.
Figure 3. Paracorporeal Pumps
Left figure is reprinted with the permission of Thoratec Corporation.
Right figure is reproduced with permission from Berlin Heart GmbH.
Figure 4. Axial vs. Centrifugal-Flow Pump Design
A, Blood flow is parallel to spin axis. The image is reprinted with the permission of Thoratec Corporation.
B, Blood flow is perpendicular to spin axis. The image is reprinted with permission from HeartWare.