Device Simulates Functions of Medical Leeches

Originally Published MDDI January 2002

R&D DIGEST

Device Simulates Functions of Medical Leeches

Once considered a symbol of the practices of medieval physicians, medical leeches have emerged as a useful component of certain modern therapeutic protocols. Their use has been shown to be particularly beneficial in reestablishing blood flow to compromised tissue in cases of venous congestion. Despite the usefulness of medical leeching procedures, the practice has generally suffered from the reaction of patients. In addition, leeches are not sterile and can cause bacterial infections. Healthcare workers tend not to like working with leeches, which can sometimes slip off patients and reattach themselves to parts of the body not in need of therapy.

A new mechanical device, however, could overcome these limitations. The system, developed by researchers at the University of Wisconsin–Madison led by head and neck surgeon Gregory Hartig, MD, is a mechanical leech capable of performing in a fashion similar to nature's version.

Nadine Connor, of William S. Middleton Memorial Veterans Administration Hospital (Madison, WI) and part of the university research team, says medical leeches are used to reestablish blood flow. She explains, "Venous congestion is a complication that can occur after reconstructive surgery. What happens is the arteries pump blood into the reconstructed tissue, but the associated veins do not let the blood flow out, usually because the veins have become clotted. The excess blood in the tissue, if severe enough, can deprive the tissue of oxygen and other nutrients and can cause it to die." A medical leech consumes this excess. After it detaches from the body, anticoagulants it has secreted allow blood to continue flowing through the tissue.

According to Michael Conforti, MD, another of the mechanical leech's inventors, the device provides an improved method for delivering and dispersing heparin to affected tissue. He adds that the device's porous tip, which is implanted just beneath the skin, rotates to further inhibit coagulation. Unlike a real leech that consumes a limited volume of blood, the mechanical leech is essentially insatiable, which also can enhance treatment.

Conforti says, "Our focus at the current time is the treatment of venous congestion, in which leech therapy is thought to be beneficial. If leeches are shown to be beneficial for other maladies, a mechanical device may lead to a more efficacious, less psychologically stressful treatment for those situations as well."

Ongoing research is expected to progress to increasingly complex tissues. "The current prototype has been tested on medium and large areas of congested tissue," says Conforti. "With further prototyping, we hope to be able to produce a device that can treat more complex tissue types, such as ear and nose replants. These tissue types are obviously less ‘fleshy' versus a skin or skin-muscle flap, and they will require different interfaces between the device and the tissue in order to effectively keep a wound open and bleeding."

Although no human trials have been conducted to date, Conforti believes that "the device will be favorably received by both the medical community and the patients it is used on. The alternative usually sends shivers down peoples' spines." It may be two to three years, however, before the mechanical leech is available to the healthcare market. He adds, "There has been interest by the medical device industry and we feel that the market potential is great enough to make commercialization of the device a profitable venture."

Copyright ©2002 Medical Device & Diagnostic Industry