Methylene blue based protein solder for vascular anastomoses: An in vitro burst pressure study

Background and Objective: Attempts at sutureless anastomoses have used prot ein-based solders containing chromophores [Oz et al., J Vase Surg 1990;11:7 18; Poppas et al., J Urol 1998;150:1052] to enhance the strength of laser a nastomoses. Reports have described the use of indocyanine green [Oz et al., Surg Forum 1989;316.], fuschin, and fluorescein isothiocyanate as chromoph ores [Chuck et al., Lasers Surg Med 1989;9:471; Vance et al., Lasers Med Sc i 1988;3:219]. Methylene blue (MB) is a chromophore with absorption peaks i n the 600-700 nm region whose use has not keen reported in laser-assisted v ascular anastomoses. Therefore, we set out to produce and characterise a RI B-containing protein solder. The absorption and burst pressure characterist ics have been investigated and described as well as a brief review of the c hemical and biological properties of MB. Study Design/Materials and Methods: The MB and porcine serum albumin (PSA)- based solder was produced and used to form end-to-end anastomoses in porcin e splenic arteries. The solder was activated using a laser diode emitting a t 670 nm. The burst pressures of the anastomoses were tested, and the resul ts analysed as a function of MB concentration and absorption. In addition, the relationship between MB concentration and absorption was examined. Results: A dose-response relationship was found between the measured absorp tion of the solder and the burst pressure of the anastomoses formed. Burst pressures exceeding physiological levels were found. Changes in MB concentr ation revealed a marked negative deviation from Beer's law at 670 nm, owing to the monomer-dimer-trimer equilibria, Conclusion: PSA with MB solder is able to form high-quality end-to-end anas tomoses, with immediate burst pressure profiles similar to those previously described for sutured [Quigley et al., Microsurgery 1985;6: 229], lasered [Quigley et al., Microsurgery 1985;6:229], and soldered anastomoses [Small et al., J Clin Laser Med Surg 1997;15:205]. The relationship between burst pressure strength and chromophore absorption is discussed. Lasers Surg. Med . 26:323-329, 2000. (C) 2000 Wiley-Liss, Inc.