Patch Angioplasty in the Rat Aorta or Inferior Vena Cava

The overall goal of this procedure is to install vascular biomaterials into either the arterial or venous environment. This method can help answer key questions in the difference of neointimal hyperplasia that forms on biomaterials placed in the arterial or venous environments. The main advantage of this technique is that it's easy to learn, and need only a short time to perform.

After confirming a lack of response to toe pinch, administer buprenorphine via IP as a preemptive analgesia. Remove the hair on the animal's ventral abdomen. Next, use micro scissors to trim a bovine pericardial patch to a 3 x 1.5 x 0.6 millimeter size, and soak the patch in 10 milliliters of sterilized saline in a cell culture dish for five minutes.

While the patch is soaking, disinfect the incision site with a topical antiseptic, and cover the animal with a surgical drape. Under a dissecting microscope, use a scalpel to make a midline abdominal incision extending from the xiphoid process to just above the pubis, and insert a retractor into the incision. When the abdominal cavity has been opened, extract the bowel from the abdominal cavity to the right side of the animal, and wrap the tissue in saline-soaked gauze.

Using sterile cotton swabs, expose the infrarenal vena cava, or IVC. Then use forceps to dissect the IVC free at approximately two millimeters below the origin of the renal veins, and use 6-0 nylon sutures to ligate and divide all of the lumbar and tributary veins. Next, place two microsurgery clips across both the proximal and distal infrarenal IVCs, and use a 25 gauge needle to puncture the anterior wall of the IVC, using scissors to enlarge the puncture to around three millimeters.

Now completely close the venotomy with the patch and 10-0 nylon sutures. Remove the distal clamp to vent the patch, followed by removal of the proximal clamp to restore the blood flow to the IVC. Then observe the patch for 30 seconds without compression to confirm hemostasis, and return the bowels to the abdominal cavity, closing the abdomen with a running suture according to approved animal protocols.

Apply postoperative care, including analgesia and wound care in accordance with the recommendations of the institutional animal care and use committee, monitoring the animal until full sternal recumbency is achieved. For a patch arterioplasty, soak the trimmed patch in sterile saline as just demonstrated. After extracting the bowels as for the venoplasty, use sterile cotton swabs to expose the aorta.

Then free the aorta approximately two millimeters below the origin of the renal arteries, and use 6-0 nylon sutures to ligate and divide all of the lumbar arteries. Next, clamp the infrarenal aorta, and use a 25 gauge needle to puncture the anterior wall of the aorta. Use scissors to enlarge the puncture to around three millimeters.

Then completely close the arteriotomy with the patch and running 10-0 nylon sutures. Remove the distal clamp first to vent the patch, followed by removal of the proximal clamp to restore the blood flow to the aorta. After confirmation of hemostasis, return the bowels to the abdominal cavity, and close the abdomen with a running suture according to the approved animal protocols, providing postoperative care as just demonstrated.

On day seven harvested IVC patches, there is a distinct layer of thick neointima on the lumenal side of the patch with more cells accumulated in the neointima. In the arterial patch, there is typically a much thinner neointimal layer, with only a few cells attached to the lumenal side of the patch. Indeed, quantitative comparison of the neointima thickness between the two patch environments indicates that the neointima is significantly thicker in the venous patch environment compared to the artery patch, suggesting that the patch venoplasty model is superior to the other models for acquiring a thick neointima in a short period of time.

Once mastered, this technique can be done in 30 to 40 minutes if it's performed proper. After its development, this technique paved the way for researchers in the field of vascular biology to explore neointimal hyperplasia in vascular disease.