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Harrison Ring shows promise as a new tool for creating an anastomosis

Fri, 10/06/2017 - 14:50
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Proof-of-concept study in patients shows use of the Harrison Ring is safe and easy for surgeons to use

An experimental device that employs a pair of magnets offers surgeons a new safe and simple alternative to standard methods for creating an anastomosis for the first time in nearly 50 years. In its first proof-of-concept clinical trial in humans, the device was easy for surgeons to use, even with patients who required complicated surgical reconstruction. It also was safe; none of the patients had any complications related to the use of the device or the anastomosis it fashioned. Findings from the clinical trial were published in a paper, ‘Magnetic Compression Anastomosis (Magnamosis): First-In-Human Trial’, in the Journal of the American College of Surgeons.

Magnetic compression anastomosis applies the force of magnetic attraction to form an anastomosis without sutures or staples. The technique utilises a Magnamosis device, which houses two rare earth magnets in a specially engineered medical grade polycarbonate shell. The magnetic implants have different polarities so they are drawn to one another. The magnets also have different shapes - one is convex and one is concave - so they fit smoothly together. In the formation of an anastomosis, a magnet is placed in each side of the tube that is being surgically connected, and then the magnets are drawn together, compressing the tissue between them and blocking blood flow.

“The tissue between the magnets dies off, a hole forms from the necrotic tissue, and the surrounding area heals. Once the connection is fully formed, the magnets fall through the hole, pass into the bowel, and are excreted in the stool, leaving nothing behind,” said Dr Claire Graves Graves, lead author and research fellow at the University of California San Francisco when the study was conducted and a current resident in general surgery at Columbia University Medical Center, New York City.

In animal studies, the Magnamosis device consistently created anastomoses that were comparable or better than hand-sewn or stapled alternatives as demonstrated in tissue samples and tests of the strength of the connection.

The study presents the first-in-human prospective case series involving the device. Although the study was open to any patient who needed any size small or large bowel anastomosis to restore bowel continuity, the first surgeons to recruit patients were urologists who were treating high-risk, complicated patients. Three of five patients in the study were quadriplegic, had bladder and bowel complications and were bedridden. Two had end stage renal disease requiring dialysis and were candidates for renal transplant. Three patients had previous abdominal operations, and all five had undergone many previous urologic procedures.

Surgeons created an anastomosis using the Magnamosis device in 25 to 35 minutes. None of the patients reported problems with their anastomosis during clinic appointments or focused questionnaires over the course of follow-up. None of the patients had any complication related to the magnet, such as leaking, bleeding, or stricture.

“The development of the Magnamosis device is at a very early stage. It has an investigative device exemption from the FDA so it can be tested under clinical trial conditions. If other surgeons in other settings with other patient populations have similar results with the device, we can apply to the FDA for a 510(k) clearance and begin to bring the product into more widespread use,” said Michael Harrison, professor emeritus of surgery at UCSF.

Magnamosis was developed at the University of California San Francisco. It is being developed for marketing by Magnamosis, a private medical device company based in San Francisco. The company is developing other magnetic-driven medical devices that were designed by Dr Harrison. He is founder and president of Magnamosis.

This work was supported by the Mount Zion Health fund, the UCSF Pediatric Device Consortium, which is funded by the FDA Office of Orphan Product Development, and a grant from the National Science Foundation (Grant No. 1240380).

To access the paper, Magnetic Compression Anastomosis (Magnamosis): First-in-human Trial’, please click here

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