Murine Model of Femoral Artery Wire Injury with Implantation of a Perivascular Drug Delivery Patch

The overall goal of this procedure is to injure and denude the endothelium of the femoral artery, either while ligating the muscular branch of the femoral artery, or restoring normal flow to both vessels. This is accomplished by first isolating the femoral artery and muscular branch by blunt dissection and silk sutures. In the second step, an arterio is made in the muscular branch, and then a coiled wire is introduced to injure the femoral artery.

In the final step, the vessel is closed and the blood flow is returned to the muscular branch. Ultimately, histological stains are used to visualize the intimal hyperplasia of the artery in response to the injury at the experimental time. Points of interest.

The main advantage of this technique over existing techniques is that with our method, the muscular branch of the femoral artery is not ligated at the end of the procedure. So we first had the idea for using partial cautery when we were performing surgeries on mice that were too small for conventional techniques. This is really what inspired us to create the method of using partial cautery to close the vessels and leave the the femoral artery open.

Begin by using small surgical scissors to make a curved incision in the skin over the femoral artery of an anesthetized adult mouse. Place magnetic fixators in the incision, and then bluntly dissect the surrounding tissue to locate the femoral artery. Moisten the tissue with a sterile cotton tipped applicator dipped in saline, and then use forceps to further isolate the artery.

Next, use fine tipped forceps to gently separate the nerve from the vascular bundle, taking care not to damage the vein or the nerve. Carefully push the nerve away from the bundle to avoid stimulating it. Then gently separate the femoral vein from the femoral artery and locate the femoral bifurcation.

Loop a 6.0 silk suture under the femoral artery just distal to the bifurcation, and secure it with a hemostat to restrict blood flow to the artery, then posterior to the bifurcation loop a second 6.0 silk suture under the femoral artery, securing it to the suture with a hemostat as just demonstrated to aid in the positioning of the artery loop. Two more sutures under the muscular branch of the femoral artery. Pretti them and secure them with another hemostat.

Then moisten the tissues with more saline. Loop one suture under the femoral artery after the bifurcation and secure with a hemostat to perform the femoral artery wire injury. First, pull the proximal suture upward to restrict the blood flow into the artery.

Then slightly pull the distal and branch hemostats to expose the site for the arter otomy, and ligate the muscular branch with a suture tie. Then use micro scissors stabilized with forceps balanced on a roll of surgical tape to perform an arter otomy in the side branch of the bifurcation. Now use fine tipped forceps to gently lift the opening of the arterio and introduce the rounded end of the wire into the artery using a syringe to add one or two drops of lidocaine to the region to ease the advancement of the wire.

When the wire reaches the proximal suture, release the suture and adjust it so that the advancement of the wire is not impeded. Then insert the wire until it cannot advance. Further, allow the wire to remain in the femoral artery for one minute.

Then retract and advance the wire in a sawing motion 10 times to injure and denude the endothelium of the artery When the injury is complete, retract the wire slowly until the round end has passed the proximal suture. Then pull the suture to restrict the blood flow into the artery and finish retracting the wire to ligate the muscular branch. Tighten the remaining suture on the branch to prevent bleeding from the arterio otomy.

Next, use micro incision scissors to sever the small branch between the two sutures. Then return the blood flow to the femoral artery confirming that blood is not leaking, and trim the ends from the sutures. Alternatively, to avoid ligation of the muscular branch and to allow vascular access through the larger main femoral artery, injure the artery with the wire as just demonstrated and close the incision by lightly applying the tip of a heated fine tipped cautery to the side of the arter otomy as it cools.

When performing the partial cautery method, making the arterio in the side of the vessel increases the chances of a successful cauterization To test the success of cauterization, loosen the proximal suture and restore flow to the femoral artery. If the cautery is successful, blood flow will be restored distal to the arterio. Remove the temporary proximal and distal ties.

Finally, use sterile scissors to blunt the corners of the barrier region of a drug delivery patch. Then place the patch onto the injured femoral artery with a drug releasing side facing the vessel using forceps to adjust the patch position as necessary. Following wire injury, neointimal hyperplasia develops over a 14 to 28 day period.

As illustrated, an uninjured femoral artery will demonstrate an intact elastic lamely and a normal thickness and circumference. An injured femoral artery, however, will exhibit intimal hyperplasia and a degraded elastic lamely, as well as reendothelialization at later time points. While performing this procedure, it is important to limit the size of the otomy.

As a large arter otomy will cause the femoral artery to sever during the insertion of the wire. Additionally, a large arter otomy will be difficult to close using the cautery method without ligation. It's our hope that this method will remove some of the technical barriers for performing this technique and help people find new methods to treat cardiovascular disease.