We investigated the feasibility of selective ablation of thrombi (T) using a pulsed dye laser (PL). Canine arteries in 10 animals were traumatized with forceps proximal to a 90% external band stenosis to promote platelet adhesion during a subsequent 20 minute perfusion period. Thrombin and whole blood was then injected proximately, creating a mixed platelet and fibrin thrombus, and allowed to mature for 1-6 hours. Integrating sphere measurements determined absorption coefficients of T and vessel walls. 480Nm radiation was found to have negligible absorption by vessel wall and high absorption by T. Occlusive coronary artery (CA) T (age 3 hours) were similarly created in 26 dogs. A PL delivered 480 nm radiation in 1 µsec pulses (21-5HZ) at 8 Joules/cm2 via a new laser catheter (LC) technology in 22 dogs. T treated with PL were completely removed in all dogs and distal perfusion established within 100 seconds. In control animals (4), there was no perfusion (p=.0001). T treated with the catheter prior to PL in 13 animals had no mechanically-induced perfusion. 16 of 17 CA followed for 1-2 hours remained widely patent. All T were removed without perforation or vasospasm. Histology revealed complete removal of T without evidence of thermal injury. We conclude that selective laser ablation of CA T Is feasible. Its role in AMI bears further investigation.
Gregory, KW, Anderson, RR: Iodinated contrast fluid can replace quartz in laser catheters. Circulation (Suppl. II) 80:II-107, 1989.