INTRACORONARY ULTRASOUND FOLLOWING EXCIMER-LASER ANGIOPLASTY - AN IN-VITRO STUDY IN HUMAN CORONARY-ARTERIES

To study the ablation effects induced by excimer laser coronary angiop lasty (ELCA), we examined 41 segments of nine isolated coronary arteri es. An electronic intracoronary ultrasound device (ICUS: 20 MHz, 3.5F, Endosonics) was positioned coaxially within the vessel. Angioplasty w as performed using a 1.7 mm ELCA catheter (Spectranetics) which was pl aced in the lumen and directed vertically onto the intimal surface of the vessel (fluence: 10-50 mJ.mm-2). The laser catheter was removed af ter each lasing cycle to allow the stepwise evaluation of the morpholo gical effects of ELCA and to avoid reaching the adventitia. Ultrasound images were compared with the corresponding histological specimens. I n all cases, the ablation site could be correctly identified by ICUS. No penetration of the adventitia was seen at histology. Ablation depth was 0.31 +/- 0.18 mm as determined by histology and 0.34 +/- 0.18 mm as determined by ultrasound; the diameter of the crater was 0.63 +/- 0 .21 mm, and 0.75 +/- 0.16 mm, respectively, and wall thickness was 0.6 8 +/- 0.18 mm, and 0.83 +/- 0.20 mm, respectively. A statistical relat ionship between ultrasonic and histology measurements was only found, however, for assessment of wall thickness (r = 0.71). Conclusions: The identification of small ablation effects by ICUS was possible with gr eat accuracy and ELCA could be performed without penetration of the ad ventitial layers. However, exact quantification of the crater dimensio ns was not possible due to limitations of the axial and lateral resolu tion. Thus, for the guidance of ELCA by ICUS a further improvement in the resolution capabilities of ICUS devices is mandatory.