Carotid Artery Anastomosis With Albumin Solder and Near Infrared Lasers: A Comparative Study A. Lauto, MSc, 1 * A.H. Hamawy, MD, 2 A.B.M. Phillips, MD, 2 P.B. Petratos, MD, 1 J. Raman, BA, 2 D. Felsen, PhD, 1 W. Ko, MD, 2 and D.P. Poppas, MD 1 1 Center for Pediatric Urology and Minimal Invasive Urologic Surgery, New York Presbyterian Hospital-Weill Medical College of Cornell University, New York, New York 10021 2 Department of Urology and Department of Cardiothoracic Surgery, New York Presbyterian Hospital-Weill Medical College of Cornell University, New York, New York 10021 Background and Objective: Laser tissue-welding has been used for anastomosis of carotid arteries. During welding, thermal injury sustained by the vessel walls should be minimized to prevent thrombosis. Two different types of lasers were used and effects on tissue damage were studied in vitro and in vivo. Study Design/Materials and Methods: End-to-end anastomosis of dog carotid arteries (n  10) was per- formed by using a human albumin solder (HAS) in con- junction with Nd:YAG or diode lasers (  1.32 m and 1.9 m, respectively). The arteries were evaluated for pa- tency and evidence of histologic injury after 21 days. An- other group of arteries was laser soldered in vitro to mea- sure the intimal and adventitial temperatures by using thermocouples. Results: The arteries repaired with the diode laser sus- tained significantly less thermal damage than those re- paired with Nd:YAG laser, both in vitro and in vivo. In particular, the intimal temperature was significantly lower (P < 0.05) for the diode than for the Nd:YAG repairs (∼35°C and ∼50°C, respectively). In the latter group, the patency rate was 75%, but thrombosis occurred in 75% of the specimens at 21 days. All diode anastomoses were pat- ent and thrombosis developed in only 17% of the arteries. Conclusion: Use of the diode laser and albumin solders may provide a means to successfully repair carotid arter- ies with minimal thermal damage. Lasers Surg. Med. 28: 50–55, 2001 © 2001 Wiley-Liss, Inc. Key words: thrombosis; tissue temperature; Nd:YAG and diode lasers INTRODUCTION Laser welding of blood vessels has been proposed as an alternative method to sutures for vascular anastomosis for over 30 years [1,2]. When compared with standard sutur- ing techniques, laser tissue-welding has equivalent pa- tency rates and the repairs take less time [3,4]. In addi- tion, the strength of the anastomosis improved with the development and use of human albumin solders (HAS). The solder functions by absorbing energy, which causes it to denature and bond to the native tissue [5]. One of the difficulties of repairing vascular structures with laser welding techniques is the need to avoid thrombosis. This thrombogenesis is most likely a result of thermal injury sustained by the vessels during the repair [2]. By limiting thermal injury to the superficial layers, thrombogenesis may be prevented. Self et al. [6] reported that low tem- perature laser welding limits thrombogenicity and that this finding may improve early patency of venous and small arterial bypass grafts. Likewise, Kopchock et al. [7] have noted that laser welding done with CO 2 laser energy at high temperatures resulted in full-thickness coagula- tion necrosis and a high incidence of acute vessel occlu- sion. Gennaro et al. [8] reported comparable findings. La- ser soldering is an alternative surgical technique, with potential use in vascular surgery. In this study, we com- pared the degree of tissue injury and vessel patency rates in soldering with HAS and either Nd:YAG or diode lasers. MATERIALS AND METHODS In Vitro Laser Soldering Fresh canine common carotid arteries (diameter, ∼5 mm; thickness, ∼1 mm) were harvested from animals im- mediately after euthanasia and were divided into sections 2 cm in length. Tissue welding was performed by using HAS and either a Nd:YAG laser (  1.32 m, Premier Laser Systems, Irvine, CA) or a GaAlAs diode laser (  1.9 m, Abiomed, Danvers, MA). Tissue temperature and damage were also assessed. These two lasers were chosen because they showed promising results for artery anasto- mosis [9,10]. The welds were performed by using solder prepared with deionized water and ∼50% HA (w/w). Before irradiation, a strip of solder (dimensions ∼5 × 4 mm) was uniformly applied to the tissue with a 1-cc syringe through a 25-gauge catheter. Two K-type thermocouples were Contract grant sponsor: United States Surgical Corporation, National Institutes of Health; Contract grant number: R44-DK- 50505. *Correspondence to: A. Lauto, MSc, Department of Medical Physics, Memorial Hospital, 1275 York Avenue, New York, NY 10021. E-mail: a_lauto@hotmail.com Accepted 12 June 2000 Lasers in Surgery and Medicine 28:50–55 (2001) © 2001 Wiley-Liss, Inc.