Saline flush during excimer laser angioplasty: Short and long term effects in the rabbit femoral artery

Abstract

Background and Objective: In this study, the effect of flushing saline on arterial wall damage (medial ruptures and necrosis), intimal hyperplasia, and arterial remodeling was determined. During excimer laser coronary angioplasty saline is flushed to reduce the size of explosive water vapor bubbles formed by intraluminal delivery of excimer laser pulses in blood. Methods In the femoral artery of the rabbit, 600 excimer laser pulses (308 nm, 50 mJ/mm2 per pulse, 20 Hz) were delivered coaxially over a length of 20 mm in 10 bursts of 3 seconds each. In 24/48 procedures, saline was flushed (0.2 ml/s) via the guidewire channel. After 2 and 56 days, microscopic and angiographic results were compared. Results At 2 days, as compared to lasing in blood, saline flush had drastically reduced the incidence of dissections (2/12 vs. 11/12, P < 0.002), but had increased the extent of medial and adventitial necrosis. The latter is attributed to direct irradiation of the arterial wall. After 56 days, in the saline group, in the middle‐distal part of treated segments, medial necrosis without intimal hyperplasia was observed. However, at the edges of these lesions, intimal hyperplasia and arterial shrinkage reduced the lumen. Conclusion Flushing saline during coaxial excimer laser pulse delivery significantly reduced the incidence of vessel wall ruptures, and prevented intimal hyperplasia formation in part of the lesion. The histologic findings at 56 days are attributed to the optical window which the saline flush provides for direct ultraviolet light irradiation of the arterial wall. Lasers Surg. Med. 23:128–140, 1998. © 1998 Wiley‐Liss, Inc.

UVB-activated Psoralen Reduces Luminal Narrowing After Balloon Dilation Because of Inhibition of Constrictive Remodeling¶

“…The segments were cut in duplicate 5 μm cross sections and were stained with hematoxylin and eosin, elastin van Gieson (EvG) and picro‐sirius red (PSR). Proliferation was detected with the monoclonal MIB‐1 antibody as described previously (16).…”

Cavitation in Non-Newtonian Fluids

“…Several strategies have been proposed to minimize the negative collateral effects generated by cavitation. Van Leeuwen et al (1998) also investigated the effect of flushing saline during pulse delivery on the arterial wall damage. Oberhoff et al (1992) suggested to divide the energy of one XeCl laser pulse both spatially and in time into eight smaller pulses (pulse multiplexing) which diminishes the area radiated with each pulse and thus cavitation effects.…”

Method for disruption and re‐canalization of atherosclerotic plaques in coronary vessels with photothermal bubbles generated around gold nanoparticles

“…The lifetime of PTMB is proportional to its maximal diameter, which can be controlled by varying laser pulse fluence. The laser pulse can be delivered through an optical fiber catheter [22,23,35,36] and through optically transparent media between the catheter tip and the plaque (such as saline buffer) because blood cells would scatter and decrease the optical energy of the pump laser pulse. As the PTMBs remove a plaque tissue, the process should be repeated until the re-canalization is achieved (Fig.…”

“…Laser-induced bubbles were previously employed in the laser angioplasty [22][23][24][25][26][27]; nevertheless, the mechanism of generation of the bubbles (using the tissues as optical absorber and relatively long laser pulses) resulted in accompanying heating of the collateral normal tissues, relatively big size of the laser-induced bubbles (millimeters) and, consequently, in a thermal and mechanical damage to artery walls [16,17,28,29]. Compared to cardiovascular laser-induced bubbles [16,17,28,29], application of light-absorbing micro-and nanoparticles provided significant reduction in bubble size and in laser threshold energies, required for the generation of such bubbles [30][31][32].…”