Clinically, radiocephalic AVF created with a modified no-touch technique can increase primary patency and decrease juxta-anastomotic stenosis. To explore the mechanism of MNTT, this animal model needs to be established. The main advantage of the modified no-touch technique is to reduce injury to the external jugular vein when establishing AVF.
When dealing with the external jugular vein care should be taken to preserve the paravenous tissue as much as possible and reduce the injury to the vein. To begin, place an anesthetized rabbit in a supine position on a fixed table. Bind its limbs and incisors.
Using an electric razor, shave the rabbit's neck and upper chest, and remove the hair with animal depilatory cream. Next, using a scissor, make a three centimeter long incision between the mandible and the sternoclavicular joint. Identify the right extra jugular vein, or EJV, and make a tunnel perpendicular to it.
Place a vascular clamp along the tunnel and similarly make another tunnel at the distal EJV. Control the blood flow by applying a 4-O suture and a clamp along the tunnel. To dissect the common carotid artery, begin by exploring the CCA lateral to the trachea and medial to the sternocleidomastoid muscle.
Now, dissect two centimeters of the CCA. Using a 4-0 suture thread, control the blood flow when needed. Place vascular clamps at the distal and proximal lens of the CCA.
For phlebotomy and anastomosis, use micro scissors to dissect four millimeters of the internal part of the EJV. Then, make a four millimeter long incision in the middle of the vein. Rinse the vein with heparin solution to prevent thrombosis.
Make a similar incision in the anterior wall of the artery and rinse as demonstrated. Pull the EJV and the CCA as close together as possible. Apply Connell's technique using 8-0 non-absorbable sutures to perform side-by-side anastomosis of the vessels.
Suture the posterior wall of the vessels first, followed by the anterior vessel wall. To observe active blood flow through the anastomosis, remove all vascular clamps except for the one at the distal EJV. Using the 4-0 suture placed earlier, ligate the distal end of the EJV, then remove the distal clamp.
Remove the suture thread around the CCA. Of the 34 rabbits that had immediately successful arterial venous fistula using the modified no-touch technique, only 31 rabbits survived, resulting in a survival rate of 86.1%13 out of 34 rabbits had a functional AVF four weeks after the surgery leading to a 38.2%AVF patency rate. The patent arterial venous fistula was confirmed after four weeks.
Spiral laminar flow was observed in both vessels near the anastomosis. Upon HE staining, significant venous intimal hyperplasia was observed at the site of the arteriovenous fistula anastomosis, but not at the proximal EJV of the anastomosis. AVF animal model established using MNTT can provide technical support for further exploration of the molecular biological mechanism of juxta-anastomotic stenosis.
