Future

The future of ventricular assist devices is promising. Currently, we seem to be dealing with early prototypes. Many minor and major advances will take place in the field when we finally have a long-term device that can replace circulatory function. Nevertheless, any device should possess most of the following characteristics:

1. It must be totally implantable to lower the risk of infection significantly and to improve the quality of life for patients.

Fig. 5. One of the author's former patients standing on his tractor, taking a break from plowing his farm fields; he did this while being supported with a ventricular assist device system.

2. It must be effective enough to provide adequate blood flow to meet the variable hemodynamic needs associated with a normal lifestyle (allow for activity and mobility).

3. It must be reliable and durable. The current ventricular assist devices require a major operation to implant, and device failures require additional major surgery to change out the pumps. For FDA approval of the ventricular assist device as a destination therapy, 5-7 yr has been suggested as an acceptable length of time for durability.

4. It must be compatible with human physiology. For example, pressure wave generation over time must be acceptable to the human body, especially to the neurological system. With the axial flow pump design, diminished pulse pressure must be determined to be physiologically acceptable to the human body over the long term. Likewise, with the levitating axial flow pump design and its ability to generate adequate pulse pressures, pressure generation must be acceptable and thus likely to mimic the human physiological pressure waveform.

5. It must be small in size to ensure acceptable quality of life. Currently, the electrical motor-driven ventricular assist device is considered bulky and noisy, with significant motion associated with the slow torque motor. The future ventricular assist device must be even smaller, thus not impinging on other organ space; moreover, it must not cause pain because of motion or heaviness.

6. It must have minimal associated thromboembolic risks. The blood contact surface or physical property of the propulsion mechanism must not trigger intravascular thrombosis. Some of the current ventricular assist devices have associated adverse blood contact properties that are being addressed by aggressive anticoagulation regimens. In the future, the need for anticoagulation must be minimal. An optimal design would minimize the blood contact-related activation of the clotting cascade and thus cause minimal physical deformity of blood cells.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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