Preliminary results of intraoperative excimer laser angioplasty: phase 1: an adjunct to coronary artery bypass surgery

Smooth excimer laser coronary angioplasty (SELCA) and conventional excimer laser angioplasty: Comparison of vascular injury and smooth muscle cell proliferation

Although the excimer laser, which utilizes 'non-thermal ablation effects', has achieved encouraging results in early clinical trials, the long-term results have failed to show any advantage over conventional percutaneous transluminal coronary angioplasty (PTCA).A new system, Smooth Excimer Laser Coronary Angioplasty (SELCA), has been developed to reduce the tissue damage in the vessel wall caused by shock waves and vapour bubbles.SELCA (wavelength 308 nm, pulse duration 115 ns, repetition rate 150 Hz and energy density 50 mJ mm(-2)) lowers the amount of shock wave formation and pressure peak amplitude in the surrounding tissue by about eight times when compared to the conventional 308 nm excimer laser (ELCA). In this preclinical evaluation, this new system was compared to ELCA. Fifty New Zealand White rabbits were stimulated by repeated weak DC impulses for a period of 28 days in order to form an atherosclerotic plaque in the right carotid artery. The vessels were excised 3, 7,14 and 28 days after laser irradiation for immunohistochemical analysis.SELCA and ELCA laser treatment lead to a decrease in maximal intimal wall thickness 3 days after intervention (control: 177+/-4 microm; SELCA: 131+/-22microm; ELCA: 120 +/-33microm). In the period between 3 and 28 days, a moderate increase in intimal wall thickness was observed after SELCA treatment compared to a significant increase after ELCA (28 days after intervention: SELCA: 157+/-22microm; ELCA: 274 +/-28microm). Bromodeoxyuridine (BrdU) was applied 18 and 12 h before excision of the vessels in order to determine the percent of cells undergoing DNA synthesis. The percent of BrdU labelled SMC in the intima (control: 13 +/- 2 cells mm(-2)) increased in both groups after 3 days (SELCA: 248 +/- 107 cells mm(-2); ELCA: 162 +/- 41 cells mm(-2)) and 7 days (SELCA: 162+/- 55 cells mm(-2); ELCA: 279 +/- 119 cells mm(-2)).The present results demonstrate that vascular wall injury and increase in intimal wall thickness following SELCA are reduced in comparison to the results achieved with the conventional technique. Further trials are necessary to assess whether these improvements will lead to more favourable long-term results after excimer laser angioplasty.

Comparative study of Nd:YAG laser angioplasty at 1.06 microns, 1.32 microns, and 1.44 microns wavelengths: decreased vascular spasm and early mortality with 1.44 microns laser ablation

BACKGROUND AND OBJECTIVE

Although laser angioplasty has been demonstrated to be effective for the treatment of long, complex coronary arterial atherosclerotic stenoses, there is an associated risk of acute arterial spasm, dissection, and perforation as well as a significant restenosis rate. It has been postulated that the use of lasers emitting at wavelengths designed for radiation absorption by water would decrease local tissue trauma.

STUDY DESIGN/MATERIALS AND METHODS

We have examined the use of a Nd:YAG laser designed to emit at 1.44 microns, an absorption peak for water, and compared the results of laser ablation at 1.06 microns, 1.32 microns, and 1.44 microns wavelengths. Nd:YAG laser angioplasty was performed in the abdominal aorta of White Leghorn roosters. Acute and chronic vascular trauma was assessed by contrast angiography and histological analysis.

RESULTS

There was a significant decrease in early mortality with 1.44 microns laser ablation. This decreased mortality after 1.44 microns ablation was associated with a decrease in vascular spasm, perforation, and thermal damage. Atherosclerotic plaque development at follow up was decreased with 1.44 microns ablation but this was not significant.

CONCLUSION

1.44 microns laser ablation decreases early vascular trauma and mortality and may decrease subsequent atherosclerotic plaque development.