1515 Brief Communications June 1987 American Heart Journal Carbon dioxide fiberoptic ieser for treatment of coarctation of the aorta Benjamin Zeevi, M.D.,* Dov Gal, D.V.M.,*** Armand Abramovici, D.Sc.,** Michael Berant, M.D.,* Leonard C. Blieden, M.B., B.Ch.,* and Abraham Katzir, Ph.D.*** Petah Tiqva and Tel Aviv, Israel Much research is currently being undertaken to develop laser techniques for the treatment of acquired cardiovas- cular diseases.l There is only one preliminary report of the potential application of argon laser for congenital heart disease, including treatment of coarctation of the aorta in the newborn.2 In the present report, the use of a flexible CO, laser catheter for the potential treatment of coarcta- tion of the aorta in children is described. Segments of the descendingaorta including a severely coarcted areawere removed during repair of coarctation of the aorta by end-to-end anastomosis in two boys (1 ‘/z and 3-yearsold, respectively). The segments were immersed in 0.9% saline solution at a temperature of 4” C. The laser irradiation was performed 24 hours later in room air. The CO, laser source wasan Apollo model 580. An optical fiber of 0.9 mm in diameter that was produced by extrusion of silver chloride-silver bromide crystals through suitable dyes at an elevated temperature was inserted into a regular No. 6 French cardiovascular catheter. The distal tip of the catheter with the optical fiber was positioned perpendicularly and in contact with the coarctation mem- branes,which were approximately 1 to 2 mm in thickness. No manual pressure was applied to the catheter. Pulsed laserirradiation wasperformed with a mean power output of 2.3 W at the tip of the catheter for periodsof 0.6 second, until dissolution of the membranes was achieved, as judged by the formation of new lumens about 4 x 5 mm and 3 x 4 mm in diameter (Fig. 1). In the first casewe used 12 pulses and in the second 15 pulses. In some instances a single pulse perforated the membrane. In other instances,several pulses were necessary to create a perforation. The whole procedure took us less than 2 minutes. The histopathologic examination of the aortic segments revealed a thick muscular septum crossed by a central irregular lumen, lined by a thin layer (30 to 40 mm in width) of carbonized material (Fig. 2). The subjacent area showeda delicate cribriform pattern surrounded by relatively few necrotic cells and eosinophilic threads. The remaining myocytes in the coarctation membrane aswell as the aortic wall were almost unaffected, and beyond 0.3 From the *Pediatric Cardiology Unit and **Laboratory of Developmental Pathology, Beilinson Medical Center Petah Tiqva; and the ***Sackler School of Medicine and School of Physics and Astronomy, Tel Aviv University. Reprint requests: B. Z&vi, M.D., Pediatric Cardiology Unit, Beilinson Medical Center, Petah Tiqva 49100, Israel. Fig. 1. Coarcted segment of the aorta in a 3-year-old boy. Before (above) and after (below) CO, laser irradiation. The constriction opened to a diameter of 4 to 5 mm. A = proximal side;B = distal side,from which laserirradi- ation was performed. mm no laser effect was seen and no debris except the charring lining wasseen. Coarctation of the aorta is one of the most common congenital cardiac defects. The treatment of symptomatic coarctation in infants may be a life-saving procedure. There is considerabledebate as to the choice of the best operative technique for the treatment of those infants who do not respond to medical therapy, and there is still appreciable mortality and a significant recurrence rate.3 Recently, percutaneous transluminal angioplasty hasbeen proposed as a possible alternative to the surgical approach; however, it has not proven successfulin all cases.There are reports of serious complications and many cardiologistsare unwilling to useballoon treatment for this lesion.4 Laser irradiation has been used for several acquired cardiovascular conditions in adults.’ There is only one preliminary report2 of the potential application of argon laser for the treatment of congenital heart disease in children. CO, laser irradiation is probably the most suit- able for vaporization of biologic tissue,5 because it is strongly absorbed in water and the extinction length is less than 0.2 mm. The major problem is that a good fiberoptic delivery system has not yet been developed. Recently, infrared optical fibers capable of transmitting CO, laser energy have been fabricated from silver halide crystals in the schoolof Physics and Astronomy at the Tel Aviv University? These fibers are nontoxic, fIexible, and are capable of transmitting more than 10 W. We used these fibers to successfully open obstructed coarcted aortic segments with almost no damage to the aortic wall.