Assessing Vessel Perfusion via Angiography: A Technique to Introduce Contrast Agent in Descending Aorta to Visualize Blood Vessel Perfusion in Rabbit Model

A blockage in a blood vessel can interrupt the blood flowing through it. This blockage can be detected by a technique known as angiography.

To perform angiography, place an anesthetized rabbit in the supine position on a surgery platform. Incise the skin and muscle layers in the neck region to expose the right common carotid artery, or CCA, located on the right side of the trachea.

Suture the distal end of the artery to prevent movement of the tracer dye toward the head region in the subsequent steps. Create an opening in the artery below the sutured end. Use this opening to administer heparin, which prevents blood clotting. Insert a flexible guide wire through this opening in the CCA, and suture it to restrain its position.

Advance the guide wire into the lumen of the descending aorta until it is near the aortic bifurcation point at the iliac crest - the tip of the pelvic region. Introduce an angiographic catheter over the guide wire and forward it until it is positioned above the aortic bifurcation.

Inject the tracer dye through the catheter and perform angiography. The dye absorbs the electromagnetic waves, increasing the blood vessels' contrast against the background. Enhanced contrast helps monitor the blood flow into the hindlimbs and visually detect any blockages.

After confirming a lack of response to hind paw pinch in anesthetized 4 to 6-month-old rabbit, use the scalpel with the #15 blade to make a 4 to 5-centimeter long incision, just lateral to the right side of the trachea, and use blunt dissection to expose the right common carotid artery. Use small Weitlaner retractors to open the incision, and carefully isolate the carotid artery from the jugular vein and vagus nerve.

When the carotid artery has been fully separated from the nerve and jugular vein, place a 4-0 silk suture at the proximal and distal ends of the exposed artery, and tie off the distal end of the carotid with a surgeon's knot and four square knots. On the proximal end, use a vascular silicone tie to allow for tightening or loosening of the vessel as needed. Next, apply approximately 0.5 millimeters of 1% lidocaine along the exposed carotid artery and nerve to promote vasodilation and reduce nerve irritation.

Administer 500 international units of heparin IV. Place a 4-inch wire insertion tool into the artery. Bead a 0.014 inch X 185 centimeter guidewire through the insertion tool to the aortic bifurcation at the iliac crest in the descending aorta, and advance a 3-French pigtail angiographic catheter over the wire. Advance the pigtail catheter to 2 centimeters proximal to the aortic bifurcation at the iliac crest in the descending aorta, positioning the tip of the catheter between the seventh lumbar and the first sacral vertebrae. Test the location of the catheter by manually injecting 2 to 4 milliliters of contrast agent.

Once correct positioning is confirmed, administer an intra-arterial injection of 100 micrograms of nitroglycerin through the catheter to increase vasodilation. Then, administer 0.8 to 1 milliliter of 1% lidocaine through the catheter to assist with vasodilation, and flush the catheter with heparinized saline. Attach the tubing for the automated angiographic injector to the catheter, being sure to remove any air from the line.

Use the automated angiographic injector to deliver 9 milliliters of contrast medium through the catheter at 3 milliliters per second, and perform digital subtraction angiography at 6 frames per second. Select the serial images and alter the image of the angiogram using minus 40% setting to minimize the appearance of bone, and capture a complete picture of the vessel perfusion with contrast.