Neointimal hyperplasia is one of the main causes of stenosis in Arterialized veins used in arterial coronary bypass surgery in peripheral arterial bypass surgery, as well as in arterial venous fistulas vein graft. Interposition in the common carotid artery has been performed in several research projects to study the etiology of neointimal hyperplasia and therapeutic options to address it currently. However, conventional microsurgical techniques using small animal models are complicated, frustrating, and require excessive sacrifice of experimental animals to simplify the whole procedure.
This video illustrates a detailed operation protocol, which will help the novice surgeon learn the cut technique and the vein graft. Inter position in the common carted artery 21 female sprig dolly rats from a commercial breeder were categorized in three equal groups that were operated and sacrificed on day 21, 42 and 84 respectively. General anesthesia Of the animals was induced using a plexiglass box connected to an anesthesia machine set at an oxygen flow rate of one liter per minute and an easel fluorine vaporizer with 5%anesthetic gas.
In this figure, you see the scientists before transaction of the right sternal cla mastoid muscle. The external jugular vein is shown here. Here you see the scientists after transaction of the right sternocleidomastoid muscle where the right common carotid artery and the right vagus nerve are revealed.
During the following operation, the anastomosis are performed using the cuff technique. The cuffs are handmade from a plastic tube cut In a length of three millimeters. These cuffs consist Of a tubular cuff body, including the complete volume of the plastic tube and a cuff handle consisting of half of the cuff volume.
Both the cuff body and the cuff handle Are equally long. The cuff is pulled over the common keratin artery. The Vessel and the cuff handle can be safely clamped together using a mini bulldog clamp.
Afterwards, the vessel is averted and pulled over the outside of the cuff body. Then it is fixed with a silk ligature. In this way, the lumina of the cup is covered with endothelium.
The venous graft can be slipped over both cupped common carotid artery stumps and fixed with the silk ligature. To prevent thrombus formation, especially in the distal anastomosis, it is essential to fasten the vein graft tie very close to the cuff margin in order to avoid the blood from contacting the tie holding the artery in place, A 2.5 centimeter Long median cervical incision is made directly above the sternum lateral to the sternal CDO mastoid muscle. You can see the wide external jugular vein, which is completely separated from the surrounding tissues.
Here you can see the fully mobilized external jugular vein whereby the venous tributaries were ligated with seven oh silk sutures. The sternal chito mastoid muscle is prepared here after transaction of the sternocleidomastoid muscle. You can now see the right common keratin artery.
The common keratin artery is carefully prepared by making sure not to compress the artery or the vagus nerve, And now you can see the common keratin artery in its entire length. Then it is ligated twice in the middle with seven oh silk sutures. Thereafter, the common carotid artery is transected right between the two ligatures.
A nylon cuff consisting of a body and a handle is then slipped over the distal end of the common keratin artery whereby the cuff handle lies behind the vessel. Then the cuffed end of the distal common keratin artery is clamped with a mini bulldog clamp right on the cuff handle. This ensures stability.
Subsequently, the artery is cut directly behind the ligature whereby the resulting arterial stump should be as long as the cuff body. The arterial lumen is rinsed with heparin saline solution. Then the ligation loop is set aside.
Immediately thereafter, the arterial stump is pulled up and is slipped like a sleeve over the cuff body. Subsequently, the ligation loop is pulled tightly and knotted to prevent the artery from slipping out of its sleeve. We use a trick both the arterial wall and the suture of simultaneously pinched with a pair of forceps and the left forceps make the knot.
Then the same procedure is repeated for the proximal arterial stump slipping the cuff over the proximal end of the cuffed common keratin artery Clamping, Cutting the artery Rinsing, Placing the ligation loop over the arterial stump, slipping the arterial stump over the cuff, and finally knotting the ligation loop. A one centimeter long segment of the clamped external jugular vein is excised. The two cuffed arteries are too far apart from each other for the venous interposition to approximate the correct distance for the procedure.
A three oh Vicryl suture is looped around each mini bulldog clamp and both sutures are crisscrossed. Then the sutures are pulled in opposite directions, thus enabling the proper positioning of the cupped arterial stumps. Rinsing with heparin saline solution.
Once suture is looped around the cupped distal keratin artery, then one end of the reversed and rinsed vein segment is slipped over the cuffed distal keratin artery. Then the suture is knotted in the correct position. Hereby it is important to ensure that the ligation incorporates the whole circumference of the vein graft.
Now the vein segment is again rinsed with heparin saline solution, and the other end of the vein segment is slipped over the proximal keratin artery stump. Subsequently, the ligature is completed. Here you can see the complete venous interposition graft.
Thereafter, the two mini bulldog clamps are removed. First, the distal one and then the proximal one. Finally, the arterial lies venous interposition graft is in place.
Pulsation can be seen in the common carted artery and the venous graft. After removing the clamps for the wound closure, a subcutaneous running suture is applied with four oh Vicryl whereby a three oh Vicryl suture is used for the cutaneous running suture. The animals recovered on a flat paper bedding under an infrared warming lamp.
The animals were postoperatively injected with brine norphine in a concentration of 0.03 to 0.05 milligrams per kilogram body weight SC every eight to 12 hours for two days, 100%of the animals survived at the time point of sacrifice. Moreover, the graft patency rate was 60%for the first 10 operated animals and 82%for the remaining 11 animals. The blood flow at the time of sacrifice was eight plus or minus three milliliters per minute.
By using the cuff technique vessels with different luminal diameters can be anastomosis. It is important to ligate the complete circumference of the cuffed and TED vessels to avoid bleeding after reperfusion. To prevent thrombus formation, especially in the distal anastomosis, it is essential to fasten the vein graft tie very close to the cuff margin in order to avoid the blood from contacting the tie holding the artery in place.
This model is very suitable to simulate hemodynamics of high blood velocity and low shear stress and to study mechanisms which affect the development of neointimal hyperplasia. Unlike the procedure using the caval vein as a graft, this auto transplantation using the external jugular vein as the graft reduces the necessary number of experimental animals by half. Ultimately, interposing an external jugular vein graft in the common keratin artery is a sophisticated microsurgery technique.
This video helps Sonata surgeon master this in minimum time with a lower waste of experimental animals. This model is an excellent means for novice surgeons to practice the cuff technique that is currently used in solid organ transplantation In small animals.
