Effect of blood upon the selective ablation of atherosclerotic plaque witha pulsed dye laser

Abstract

Laser angioplasty systems with laser energy preferentially absorbed by atherosclerotic plaque may offer a safe method of plaque removal. This study evaluated the effect of blood upon selective energy absorption using a pulsed dye laser at 480 nm. Intra-arterial laser irradiation of normal rabbit femoral arteries demonstrated a perforation threshold energy with blood perfusion of 13.1 mJ per pulse compared to 87.9 mJ with saline (P less than .0001), indicating a deleterious effect in the presence of blood. An adverse effect upon arterial healing at 3 days was noted in sheep following intra-arterial irradiation during blood but not saline perfusion. Normal and atherosclerotic human aorta ablation thresholds differed significantly (P less than .0002) under saline (plaque: 20 mJ and normal: 120 mJ) but the difference under blood (plaque: 5 mJ and normal: 20 mJ) was not significant. We conclude that absorption of laser energy by blood can reduce the effect of differential absorption by endogenous chromophores in normal and pathologic vascular tissues and, therefore, removal of blood may be a prerequisite for selective ablation of atherosclerotic plaques.

Photographic studies of laser-induced bubble formation in absorbing liquids and on submerged targets: implications for drug delivery with microsecond laser pulses

“…It has been shown that the rapidly expanding and collapsing bubble induced by pulsed-dye laser radiation can cause perforation, dissection, and other unwanted tissue effects. 18,15 The hydrodynamic pressures arising for the bubble expansion and collapse, however, could be harnessed under controlled circumstances for photomechanical drug delivery. Currently, two strategies to reduce the bubble dimensions are clinically used.…”