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In animal studies, a team led by Stanford microsurgeon Professor Geoffrey Gurtner used a poloxamer gel and bioadhesive rather than a needle and thread to join together blood vessels, a procedure called vascular anastomosis. Lead authors of the study were Stanford postdoctoral scholar Doctor Edward Chang and surgery resident Doctor Michael Galvez.
The big drawback of sutures is that they are difficult to use on blood vessels less than 1 millimetre wide. Gurtner began thinking about alternatives to sutures about a decade ago. "Back in 2002, I was chief of microsurgery at Bellevue in New York City, and we had an infant — 10 to 12 months old — who had a finger amputated by the spinning wheel of an indoor exercise bike," said Gurtner. "We struggled with reattaching the digit because the blood vessels were so small — maybe half a millimetre. The surgery took more than five hours, and at the end we were only able to get in three sutures. "Everything turned out OK in that case," he continued. "But what struck me was how the whole paradigm of sewing with a needle and thread kind of falls apart at that level of smallness."
Sutures are troublesome in other ways, too. They can lead to complications, such as intimal hyperplasia, in which cells respond to the trauma of the needle and thread by proliferating on the inside wall of the blood vessel, causing it to narrow at that point. This increases the risk of a blood clot getting stuck and obstructing blood flow. In addition, sutures may trigger an immune response, leading to inflamed tissue that also increases the risk of a blockage.
The new method could sidestep these problems. "Ultimately, this has the potential to improve patient care by decreasing amputations, strokes and heart attacks while reducing health-care costs," the authors write in the study.
The researchers used a simple halogen lamp to heat the gel. In tests on animals, the technique was found to be five times faster than the traditional hand-sewn method, according to the study. It also resulted in considerably less inflammation and scarring after two years. The method even worked on extremely slim blood vessels — those only 0.2 mm wide — which would have been too tiny and delicate for sutures. "That's where it really shines," Gurtner said.
Poloxamers have been used before as a vehicle for delivering drugs, including chemotherapeutics, vaccines and anti-viral therapies. Researchers have used Poloxamer 407 to occlude blood vessels in experimental animals for the purpose of evaluating the gel's safety and efficacy in so-called "beating heart surgery," in which certain vessels need to be temporarily blocked to improve visibility for the surgeons performing a coronary artery bypass.
Although other sutureless methods have been developed, they generally have not produced better outcomes, the authors said. "Often, the use of microclips, staples or magnets is itself traumatic to blood vessels leading to failure rates comparable to or higher than sutured anastomoses," they wrote.
"This is a novel approach to anastomosis that could play a valuable role in microvascular surgery," said Doctor Frank Sellke, chief of cardiothoracic surgery at Brown University Medical Center, who was not involved in the study. "But it really needs to show that it holds up in clinical trials."
The authors say further testing on large animals is needed before human trials can begin, but they note that all of the components used in the technique are already approved by the FDA. "This technology has the potential to progress rapidly from the 'bench to bedside,'" they write.
MEDICA.de; Source: Stanford University Medical Center