Published online Nov 14, 2020. doi: 10.3748/wjg.v26.i42.6614
Peer-review started: August 12, 2020
First decision: August 22, 2020
Revised: August 29, 2020
Accepted: September 10, 2020
Article in press: September 10, 2020
Published online: November 14, 2020
The feasibility of magnetic compression anastomosis (MCA) has been confirmed by previous studies; however, there is still a risk of long-term anastomotic stenosis. In fact, anastomat influences the outcome of MCA in terms of pressure and size. High pressure increases the risk of leakage, while small size causes anastomotic stenosis or even closure. One defect of traditional MCA lies in the correlation between the size of anastomosis and the MCA device. For traditional MCA devices, a large size has represented large pressure, eventually leading to increased leakage, meaning “large size & large force”.
Studies have shown that there is a risk of long-term anastomotic stenosis and even closure after MCA; this has restricted further clinical application of MCA.
This study aimed to explore the optimal size and pressure of the MCA device for intestinal anastomosis in rats. Thereafter, a novel MCA device (“fedora-type” MCA device) was developed to simultaneously meet the requirements of pressure and size.
We designed the following two experiments. First, based on the anatomical characteristics of rat intestines, we used traditional nummular MCA devices with all possible sizes to conduct ileac side-to-side anastomosis. Based on the short-term results, we determined the appropriate pressure range required for MCA. According to the long-term results, we confirmed the minimum size required to avoid anastomotic stenosis or closure. Second, based on the results of the former experiment, we introduced a novel design concept, referred to as the “fedora-type” MCA device, to simultaneously meet the requirements of both pressure and size, so that stable anastomosis could be formed.
The optimal size range was 5-6 mm for ileac side-to-side anastomosis in the rat model (the diameter of the MCA device should be within 120%-140% of the enteric diameter). When the size was smaller than 5 mm, anastomotic stenosis or closure occurred. This study also demonstrated that 54.56 ± 1.40 kPa to 126.07 ± 1.38 kPa was the optimal compression pressure range. Traditional MCA cannot meet both of these requirements. This newly developed “fedora-type” MCA device consisted of a nummular magnet and a larger sheet metal. This allowed for control of the compression pressure by adjustment of the magnet, and for optimal size by allowing for the sheet metal to be changed. The novel design broke the internal connection between size and compression pressure in MCA devices and allowed for a large size and low pressure. Of all the different designs for the fedora-type MCA device used, the Φ4 mm nummular magnet with a Φ6 mm sheet metal could safely form anastomosis after operation and ensure long-term stability.
The diameter of the MCA device should be larger than 120% of the enteric diameter to avoid stenosis. This novel anastomat controlled pressure and optimized the size respectively, thus meeting our stipulated requirements for a large size and small force device. The “fedora-type” MCA device for this model, using a Φ4 mm nummular magnet with a Φ6 mm sheet metal, safely formed anastomosis and ensured long-term anastomosis.
Models in larger animals and further clinical trials are needed to test this hypothesis and guide clinical application.