Dec. 13, 2001 MADISON, Wis., Dec 12 -- Since at least the time of the ancient Egyptians, the leech has at times been a prevalent tool in the physician's medical kit. So intrinsic was the leech to the practice of the medical arts in antiquity and the medieval world, in fact, that the very name 'leech' was at times synonymous with the title 'physician.'
But now, after millennia of service, the medicinal leech may finally have met its mechanical match, a novel device that effectively performs the same function as the medicinal leech - promoting the flow of blood to compromised tissue - without the unpleasantness of having a blood-sucking parasite attached to your body.
"In the case of the leech in medicine, we think we can improve on nature," says Nadine Connor, a scientist who is part of a University of Wisconsin-Madison and William S. Middleton Memorial Veterans Administration Hospital team that has designed and tested a tiny medical device that effectively replaces the medicinal leech. "We believe a mechanical device can be more effective."
Historically, the leech's beneficial bite has been applied -- sans scientific justification -- to treat a variety of ailments, everything from headaches and stomach aches and beyond. In the context of modern medicine, the leech has reemerged as an important and effective therapy and is used exclusively to treat venous congestion.
"Venous congestion is a post-surgical complication that can occur after reconstructive surgery," Connor says. "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."
"Leeching" can be effective as it helps to reestablish blood circulation in the affected part of the body, Connor says. Most often, venous congestion arises after head and neck reconstruction, breast reconstruction, limb or digit reattachment, or other complicated procedures where tissue is moved from one place to another.
In cases of venous congestion where reestablishing the flow of blood is essential, leeches have great therapeutic value because, as they consume their meal of blood, they promote blood flow through the tissue. Even after a leech is full of blood and detaches from the body, the anticoagulants it secretes into the tissue allow the wound to ooze blood for hours afterward. The oozing promoted by the leech's natural anticoagulants also allows blood to continue flowing through the tissue.
Meanwhile, during leech therapy, which can last for up to 10 days, new veins grow into the reconstructed region from surrounding healthy tissue and help reestablish adequate blood drainage.
As reconstructive surgeries have become more complex, and as technology permits surgeons to tackle the diciest procedures, the medicinal leech has returned to vogue and large hospitals may use hundreds of medicinal leeches a year.
But leeches, obviously, have their drawbacks, not the least of which is patients' squeamishness about having leeches attached to their bodies. Moreover, leeches are not sterile and can cause bacterial infections. Nurses and pharmacists tend not to like working with leeches, and the animals can sometimes slip off patients and reattach themselves to other parts of the body not in need of therapy.
The mechanical leech developed at UW-Madison has distinct advantages over its flesh-and-blood counterpart, according to Michael Conforti, a scientist at the William S. Middleton Memorial Veterans Administration Hospital and another of the mechanical leech's inventors.
Conforti says the device can better deliver and disperse the anticoagulant heparin to affected tissue, and the device's porous tip, implanted just beneath the skin, rotates to further inhibit coagulation. Moreover, unlike the real leech, the mechanical leech is insatiable and can remove greater quantities of blood, thereby increasing the flow of blood to the tissue being treated.
"There is a big difference between what a real leech can do and what our mechanical leech can do," says Conforti. "The real leech can penetrate only so deep. Our device can act at a deeper level under the skin, tapping into larger blood vessels and treat a larger area of tissue."
"But perhaps the mechanical device's biggest advantage is that it is not a leech," says Connor: "People don't want this disgusting organism hanging on their body. This added psychological stress for both patient and family members compounds an already difficult situation."
The Wisconsin mechanical leech project is being led by head and neck surgeon Gregory Hartig, and includes Conforti and Connor. The work is supported by a Veterans Administration Rehabilitation Research and Development grant and a patent has been applied for through the Wisconsin Alumni Research Foundation.
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