Catheterization of the Hepatic Artery Via the Left Common Carotid ...

CardioVascular and Interventional Radiology

ª Springer Science+Business Media, Inc. 2006 Published Online: 2 May 2006

Cardiovasc Intervent Radiol (2006) 29:1073–1076 DOI: 10.1007/s00270-005-8268-3

TECHNICAL NOTES

Catheterization of the Hepatic Artery Via the Left Common Carotid Artery in Rats Xiao Li,1 Yi-Xiang J. Wang,2* Xiangping Zhou,1 Yongsong Guan,3 Chengwei Tang3 1

Department of Radiology, West China Hospital, Sichuan University, Chengdu, PeopleÕs Republic of China Department of Radiology, Rui Jin Hospital, Shanghai Second Medical University, Shanghai, PeopleÕs Republic of China 3 Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, PeopleÕs Republic of China 2

Abstract The commonly used approach for rat hepatic artery catheterization is via the gastroduodenal artery, which is ligated after the procedure. A new method of rat hepatic artery catheterization via the left common carotid artery (LCCA) is described. The LCCA is repaired after catheterization. The catheterization procedures included the following: (1) opening the ratÕs abdominal cavity and exposing the portion of abdominal aorta at the level of the celiac trunk; (2) separating and exposing the LCCA; inserting a microguidewire and microcatheter set into the LCCA via an incision; after placement into the descending aorta, the microguidewire and microcatheter are maneuvered into the hepatic artery under direct vision; (3) after transcatheter therapy, the catheter is withdrawn and the incision at the LCCA is repaired. This technique was employed on 60 male Sprague-Dawley rats with diethylnitrosamine-induced liver cancer, using a 3F microguidewire and microcatheter set. Selective hepatic artery catheterization was successfully performed in 57 rats. One rat died during the operation and five rats died within 7 days after the procedure. It is envisaged that as experience increases, the catheterization success rate will increase and the death rate will decrease. A new approach for selective hepatic artery catheterization via the LCCA in rats is introduced, which makes repeat catheterization of this artery possible and allows large embolization particles to be delivered by using a 3F catheter. Key words: Rat—Carotid artery—Hepatic artery—Catheterization—Hepatocellular carcinoma

*Current address: AstraZeneca R&D, Alderley, Macclesfield SK10 4TG, UK. Correspondence to: Xiangping Zhou; email: [email protected]

Selective catheterization of the rat hepatic artery is a technique commonly used for the research of transcatheter therapy for liver cancer, including the study of pharmacokinetics and pharmacodynamics of transcatheter drug delivery and transcatheter embolization [1–3]. Whereas selective catheterization of the hepatic artery via the femoral artery route is feasible in large animals such as dogs and pigs, it is difficult to perform in rats. Until now the most commonly used techniques for rat hepatic artery catheterization is the method described by Lindell et al. [1]. With that method, the ratÕs abdominal cavity is opened, and a small catheter is inserted into the gastroduodenal artery and maneuvered upward into the hepatic artery. After withdrawal of the catheter, the gastroduodenal artery is ligated. One of the drawbacks of this procedure is ligation of the gastroduodenal artery, which might cause ischemia of the gastrointestinal tract. More importantly, this procedure can be carried out only once. Repeat catheterization of the hepatic artery is not possible. Here we describe a method of catheterization of the ratÕs hepatic artery via the left common carotid artery (LCCA). After removal of the catheter, the LCCA is repaired.

Materials and Methods Catheterization Procedure Step 1: The rat is anesthetized and its abdominal cavity opened. The left posterior peritoneal cavity is exposed by pushing the intestines to the right side. The fascia layer over the abdominal aorta is gently separated. The superior mesentery artery (SMA) is identified; the celiac trunk can be found 0.3–0.5 mm above the SMA. The portion of the aorta around the level of the celiac trunk is exposed (Fig. 1A). The opened abdominal cavity is then covered with normal saline wetted gauze. Step 2: A 4–5-cm-long skin incision at the midline of the left neck above the lower edge of the thyroid cartilage is made. The

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X. Li et al.: Catheterization of the Hepatic Artery Via the LCCA

Fig. 1. Catheterization procedures. (A) Topography of abdominal aorta with the celiac trunk and superior mesentery artery in rats. AO: abdominal aorta; CT: celiac trunk; SMA: superior mesentery artery. (B) Dissociated left common carotid artery with two bulldog clamps. LCA: left common carotid artery. (C) The microcatheter in the hepatic artery lumen seen through the vascular wall during the operation. Green arrows:

portal vein; yellow arrows: hepatic artery with microcatheter; white arrows: microcatheter within hepatic artery; blue arrow: the tip of microcatheter; black arrows: hepatic artery without microcatheter inside. (D) Left common carotid artery after suture of the arteriotomy (blue arrow). There is blood filling in both sides of the incision site, indicating continuity of the artery lumen. There is no blood exudation.

LCCA is exposed by blunt dissection between the sternohyoid, sternomastoid, and omohyoid muscles, and its sheath is opened. The left vagus nerve is gently separated from the LCCA. A segment of approximately 2 cm of the LCCA is separated and exposed. The distal end of the dissociated LCCA is clamped with a bulldog clamp, and another bulldog clamp and one rubber band is put around the proximal end of the dissociated LCCA (Fig. 1B). When the bulldog clamp at the proximal end is released, the tightness of the rubber band around the artery can be adjusted to control the blood flow during the operation. The dissociated LCCA is held up gently and an oblique incision is made with a pair of ophthalmic scissors. The width of the incision should be no more than half of the vascular perimeter. The microguidewire and microcatheter set is inserted into the LCCA. After the catheter has been placed into the LCCA, the tip of the guidewire is turned to the left so that cannulation of the descending aorta is achieved (otherwise, the guidewire might be misled to the ascending aorta). The gauze covering the abdominal cavity is removed and the celiac trunk is exposed. When the guidewire is sent down to the descending aorta to the level of the opening of the celiac trunk, the microguidewire is rotated to maneuver its tip into the celiac trunk under direct vision. This maneuver can be sometimes helped by one fin-

gertip of the operator or a cotton-tipped applicator. The microcatheter is followed through the microguidewire into the hepatic artery (Fig. 1C). Step 3: After the angiography and transcatheter drug and/or embolization agent delivery, the catheter is withdrawn. The incision in the LCCA is repaired using the conventional microsuturing technique with three to five simple interrupted sutures of size 8-0 Ethicon Prolene suture (Johnson & Johnson, USA) (Fig. 1D). To prevent thrombosis formation, saline containing 25 IU/ml heparin is applied on the operation fields at consistent intervals. In total about 2–3 ml was used per rat. At the end of the operation, the heparinized saline at the operation field is flushed away with standard normal saline. The incisions on the neck and abdomen are sutured layer-by-layer. Penicillin powder can be sprayed on the wounds to prevent infection.

Experiment The above-described technique was employed in the following study. Sixty male Sprague-Dawley (SD) rats (346.85 € 82.27 g; age: 7 months) with diethylnitrosamine (DENA)-induced liver cancer were used. The animals were from the Experimental Animal Center of Sichuan University, Chengdu, China. The hepatic artery


Fig. 2. DSA of a rat liver with tumor. Multiple tumor stains are shown. C: catheter; CT: celiac trunk; RHA: right hepatic artery; LHA: left hepatic artery; GDA: gastroduodenal artery; TS: one of the tumor stains. catheterization procedure was part of a larger study in which some antitumor agents were evaluated. Before the catheterization, magnetic resonance imaging was performed to confirm the tumor burden in the rat livers. The operations were carried out in the Digital Substraction Angiography (DSA) suite under standard surgical aseptic conditions. Rats were anesthetized with intraperitoneal injection of 1% pentobarbital sodium (30 mg/kg body weight). The microguidewire and microcatheter set were 3F Special Systems (SP) (Terumo Co., Fijinomiya, Japan). Angiography was performed with the Siemens FA DSA system (power 100 kW, Axiom Artis FA; Siemens, Frankfurt, Germany) and a Mark V Provis injector system (Medrad, Indianola, PA). The contrast agent was Omnipaque 300 (Ansheng Pharmaceutical Co., Shanghai, China). The image collecting speed was set at 7.5 frame/sec for 24 sec until the end of the portal phase. The speed of the contrast agent flow was 0.3 ml/sec, the pressure was 100 psi, and the total contrast agent volume was 2.0 ml/kg. The rats were observed for 1 week after this session of experimentation. This study was approved by the Animal Research Committee of our institution and was carried out according to the Institutional Guidelines for the Care and Use of Animals.

Results Selective hepatic artery catheterization was successfully performed on 57 rats. Occasionally, the internal diameter of the LCCA of a low-weight rat (such as the rats less than 300 g in our group of rats) can be smaller than the 3F catheter, but the artery wall usually has good elasticity, and successful catheterization can still be feasible. In rats with successful hepatic artery catheterization, high-quality angiograms were obtained in all of these animals (Fig. 2). In the early phase of this study, two cases of failure during the operation were caused by adhesion of the LCCA inner wall to the catheter at the incision site. Later, we realized that covering the dissociated portion of the LCCA

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Fig. 3. Ten days after the first catheterization and suture of the arteriotomy at the left common carotid artery in a healthy rat. The left common carotid artery is exposed. Although there is mild adhesion around the carotid artery, it can be separated for repeat catheterization and its lumen remains continuous. Blue arrow: the repaired incision at the artery.

with wet saline gauze or tampon or moistening the dissected portion of the LCCA and the nearby catheter with wet saline gauze or tampon every 1–2 min could avoid this problem. After this precaution, adhesion of arterial inner walls to the catheter did not happen again. In another animal, the liver tumor invaded the celiac trunk and made selective catheterization impossible. This animal died due to the attempt to separate the celiac trunk from the tumor-encased abdominal aorta. Five animals died within 7 days after the experimental procedure. Two animals died at day 1 and day 3 postoperation due to the damage to the abdominal lymphatics. The damage to the abdominal lymphatics can be seen by the exudation of ‘‘milk-colored’’ lymphatic fluid during the operation. Thereafter, special attention was paid to the cisterna chyli, the intestine lymphatic trunk, and the right and left lumbar lymphatic trunks during the operational process, and no further deaths occurred because of this. Two rats died from tumor hemorrhage as demonstrated postmortem. One rat died 24 h postoperation, and it was considered that the surgical procedures induced the tumor hemorrhage. Another rat died at day 5 postoperation; it is unknown whether the surgery was the cause. In both of those two animals, the liver tumor burden was extensive. Another rat died 48 h after the operation. The exact reason was unknown; compromised liver function, large tumor burden, and surgical trauma are the likely causes.

Discussion We introduced a new approach for selective hepatic artery catheterization in rats, which makes repeat catheterization of

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this artery possible. Introducing a catheter system into the aorta via a carotid artery in rats has been reported [4, 5]. In many cases, the carotid artery is ligated after the catheterization [4, 5]. Because passage of a catheter along the right carotid artery might result in it passing down the ascending aorta, the left carotid is employed. Compared with Lindell et al.Õs approach in which ligation of the gastroduodenal artery is necessary after the operation [1], our approach might have less negative impact on the blood supply to the digestive system. An additional advantage of this approach is that a larger catheter can be inserted into the hepatic artery than the gastroduodenal artery approach, as the gastroduodenal artery in rats is very small. This allows the administration of larger embolization particles. The LCCA route described here can also be used for catheterization of arteries of other visceral organs in rats. This technique can also be used in combination with the gastroduodenal artery route for rat hepatic artery catheterization for repeat procedures. The technique of microvascular anastomosis has been well reported [6, 7]. Using a technique with a neodymium– YAG laser to anastomose arteries 0.8–1.0 mm in diameter, Jain [6] reported the patency rates to be as high as 92.5%. In the cases of LCCA incision repair failure, the ligation of the common carotid artery on one side would not be expected to have dramatic effects on the rat, as a powerful collateral circulation mechanism exists [8, 9]. One disadvantage of our technique is that the abdominal cavity has to be opened to facilitate the guidewire to enter celiac trunk and hepatic artery. However, we found that it was very difficult to catheterize the hepatic artery with the guidewire/catheter set inserted via the LCCA under X-ray guidance. The rats in this study with liver tumor burden did not actually undergo repeat hepatic artery catheterization. The primary aim of the study was to evaluate some antitumor agents. Repeated hepatic artery catheterization and drug delivery were not required according to the study design. However, additional pilot experiments were carried out in a limited number of healthy rats to assess the feasibility of repeat hepatic artery catheterization via the LCCA route, especially to investigate the lumen continuity of the LCCA after the catheterization, and whether postoperation adhe-

sion around the involved arteries in the abdomen and the neck would cause difficulty for the second catheterization. Our pilot studyÕs results were satisfactory (Fig. 3), and further study is planned with a larger number of animals to validate these initial results. Regarding the failure rate of our catheterization, two cases of catheter–carotid artery adhesion could have been avoided. The mortality rate can be reduced by increased experience with cases with lymphatic injury. If the study was done in healthy rats, the mortality rate could be further reduced. In conclusion, a new approach for selective catheterization of the hepatic artery via LCCA is studied. This approach can be used when repeat catheterization is required or when large embolization particles need to be administered via a catheter. Acknowledgments. We are grateful to the China Medical Board of New York and the TCM Administration Bureau of Sichuan Province, China for their grant support of our research (CMB 82-412 and TCM 2004B03, rspectively).

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