A simple method of lower extremity arteriography in the rat

Abstract

Microarteriography is commonly used to evaluate the patency of small vessel anastomoses. Several relatively simple methods of microarteriography have been described, but none provide enough detail of the operative technique to allow the novice to perform this procedure. The authors provide a detailed simplification of the technique as described by Zhang et al.1 utilizing materials that are inexpensive, reusable, and commonly found in the laboratory setting. After approval by the Institutional Animal Care and Use Committee, six retired-breeder laboratory rats were anesthetized and underwent endoscopic microanastomosis of the femoral artery. Seven-day patency was evaluated by arteriography as described herein. High-quality X-ray images and slides were obtained with this technique by a novice laboratory surgeon. TECHNIQUE Vascular AccessGeneral anesthesia is obtained. The midline abdominal skin and subcutaneous tissue are infiltrated with 1% lidocaine with epinephrine for added analgesia and hemostasis. It is then opened longitudinally with a 3 cm incision. Cotton-tipped swabs are used to move the small intestines, cecum, and ascending colon to the right and the stomach and descending colon to the left. Moist gauze sponges protect the abdominal wall and bowel from desiccation. The aorta and vena cava are now easily visible in the retroperitoneum, which is entered by teasing the thin film of tissue (posterior peritoneum) with dry cotton-tipped swabs. The operating microscope or endoscope provide visual assistance for isolation of the aorta from the origins of the renal arteries to the aortic bifurcation. Microforceps are used to tease and divide the adventitia of the vessels by pulling toward the vena cava since this vessel is thin-walled and more susceptible to injury than the aorta. Control of the aorta is obtained with rubber bands that are cut, passed around the aorta, and reapproximated with a hemostat. Gentle upward traction on both (proximal and distal) rubber bands isolates and stabilizes the infrarenal aorta for 50-70% transverse proximal aortotomy. This is easily and accurately created by transverse insertion of a single blade of the straight microscissors. Insertion of the CatheterThe catheter is Dow Corning's (Midland, MI) silastic medical grade tubing (OD ‫ס‬ 0.6 mm; ID ‫ס‬ 0.3 mm) of 15 cm length and requires preoperative preparation. One end of the catheter is beveled to allow easy and rapid introduction and a blunt 23-gauge needle is inserted into the other end to accommodate a 5 ml syringe. It is then flushed with heparin and ready for insertion. This size of catheter is small enough to be easily introduced into the lumen of the rat aorta, yet large enough to provide a snug fit and prevent back bleeding (Fig. 1). It is introduced immediately following aortotomy and advanced to the bifurcation of the aorta. The proximal rubber band is replaced by a single microclip, which then provides proximal control. Pliability of the silastic tube prevents dislodging during manipulation of the animal.