Anastomotic concept – 120 degrees, 12 stitches
To safely match the vessel size we will use 12 stitches for the anastomosis. The stitches are placed following the 120-degree concept as indicated on the screen and previously presented in the chicken leg model. Since the vessel wall is thinner and more fragile than that of the femoral artery in the chicken leg, we will be using thinner 10.0 suture, with a smaller needle.
Anastomosis – 120 degrees, 12 stitches
The first stitch is placed and its knot is tied. The second stitch is placed exactly 120 degrees from the first on both vessel stumps. The third stitch is placed midway between the first two. A needle test is performed to evaluate accuracy of stitch placement. Placing stitches four and five completes the anterior wall. Here is the finished front wall. Now the approximator is flipped over and the back wall checked for potential backstitches tying the front and back wall together.
The sixth stitch is placed in the middle of the back wall and all consecutive mstitches are placed respecting the rule of placing each stitch midway between its neighbors.
When the anastomosis is finished release the distal clamp first. This way, if bleeding occurs, it will be less dramatic, as the retrograde flow initially filling the vessel has a relatively low pressure. Wait for 30 seconds to allow fibrin formation to occur at the anastomosis. Gently place a cotton swab on the anastomosis to keep the operating field clean and to increase the pressure inside the anastomosis gradually when releasing the proximal clamp. If a minor leakage moccurs, you can stop it by pressing the cotton swab down on the anastomosis and waiting for a minute. Major bleeding, however, needs to be re-clamped quickly, the operating field cleaned and the source of bleeding identified and repaired with additional stitches.
Identifying the source of bleeding
Once a bleeding occurs you should re-clamp the vessel quickly, then proceed thoughtfully and calmly since the loss of just a few milliliters of blood can put your rat at substantial risk. If the source of bleeding should not be immediately apparent, resist the urge to try and identify it by repeatedly re-opening the
clamp. First clean the work-field to reduce the amount of blood coloring it, then submerge the vessel before re-opening the clamps to look for a jet of blood within the water.