CIMIT Forum: Device Failure: What are the Issues?

Related Forum Topics

Mechanical Cardiac Assist/Total Artificial Heart: Present and Future

10.7.2008

Device Failure: What are the Issues?

SPEAKER:
Robert Padera, Jr., MD, PhD: HMS

MODERATOR:
Frederick J. Schoen, MD, PhD: BWH, HMS, CIMIT

Summary
Wikipedia

Device Failure: What are the Issues?

Pathologists are in a unique position to offer feedback to biomedical engineers designing devices to be implanted in the body. When a patient with an implanted device dies, an autopsy is often performed, and these autopsies allow pathologists to better understand how biomaterials affect the body and how the body affects biomaterials. Today’s implanted devices have both local and systemic effects. Foreign materials inside the body can cause inflammation, infection, and thrombosis; and these materials can also be toxic. The body, for its part, is sometimes responsible for device fatigue, corrosion, calcification, and degradation.

When an artificial heart or ventricular assist device (VAD) is explanted from the body, pathologists often observe thrombosis, or clotting, on the device itself or near the point at which the device makes contact with living tissue. This clotting occurs because the body detects the foreign materials present in the device or because the device causes pockets of blood to move more slowly than normal. Patients with implanted cardiac devices often take anti-coagulants to prevent the formation of blood clots, but this anti-coagulation must be carefully controlled to prevent hemorrhages.

Infection is another risk posed by implantable devices. Most artificial hearts have featured external drivelines, which can become infected relatively easily with pathogens that are difficult to eradicate. Fungal infections within the devices themselves have also been observed.

A number of other problems are possible, ranging from the erosion of the stomach wall to the fusing of the aortic valve in patients with VAD’s. Designers of implantable devices must analyze these past failures so that new devices will be better than their predecessors.