To begin, position the anesthetized rat for the ultrasound scanning of the inferior vena cava or IVC. Apply a conducting gel to the abdomen and orient the transducer in a transverse position. Using two-dimensional imaging mode or B mode, lower the 10 megahertz linear probe on the center of the abdomen.
When the abdominal vessels come into view, differentiate the IVC from the abdominal aorta with compressibility and flow assessment. Once the IVC is located, identify the midsection in the middle third portion inferior to the renal veins and superior to the IVC bifurcation. At the midsection IVC, measure the wall to wall diameter in the transverse view using the cross-sectional B mode image, recording the widest diameter of the vessel.
Store the data using compact disks as DICOM files. Clean the abdomen with gauze-soaked chlorhexidine scrub and chlorhexidine solution three times. Place the sterilized cling film as a surgical wrap to cover the rat thorax and abdominal area.
Using iris scissors, make a three centimeter ventral midline incision approximately two centimeters below the xiphoid process through the skin and abdominal wall. With a sterile saline-soaked gauze, reflect the intestines to the animal's right side. Place a wire speculum in the incision to allow IVC visualization.
Then using a sterile cotton tipped applicator, perform a blunt dissection. Employing a low temperature fine tip cautery, cauterize all IVC lumbar branches from the renal veins to the iliac bifurcation, and ligate side branches with 7-0 non-absorbable polypropylene sutures. Place a proximal curved vascular micro clip on the IVC, which is separated from the aorta and is inferior to the renal veins.
Place a straight micro clip on the distal IVC superior to the iliac bifurcation. Place an 8-0 nylon U-stitch suture caudal to the left renal vein centered on the anterior surface of the IVC. Insert a 0.014 millimeter sharpened guide wire with the venoplasty balloon backloaded retrograde to blood flow into the infrarenal IVC caudal to the curved micro clip.
Advance the balloon into the mid IVC using the Seldinger technique. Remove the sharpened guidewire and using a 20 milliliter inflation syringe, inflate the venoplasty balloon for three minutes with a 10 to 15%IVC overstretch. Flush sterile saline to all the systems before IVC cannulation to avoid air embolism.
Tighten the U-stitch upon venoplasty balloon deflation and removal. Then remove the micro clips and close the laparotomy site in a two-layer fashion using a 3-0 polyglactin absorbable synthetic suture. Close both the abdominal wall and skin in a continuous pattern.
Recover the rat in an individual cage and observe it for 30 minutes under a heating lamp placed 24 inches away from the cage before returning it to its original housing unit. Average pulsed wave doppler flow velocity in the inferior vena cava of the rats after clip placement of the vessel was significantly reduced.
