ANGIOGRAPHIC CHANGES (DOTTER EFFECT) PRODUCED BY INTRAVASCULAR ULTRASOUND IMAGING BEFORE CORONARY ANGIOPLASTY

Intravascular ultrasound (IVUS) imaging of the coronary arteries has r ecently been introduced for the study of coronary lesions, but the ang iographic effects produced by an IVUS examination before coronary angi oplasty are unknown. Accordingly, the feasibility of and the potential angiographic changes caused by IVUS study (4.8F catheter) of severe c oronary lesions was prospectively studied. Thirty consecutive coronary lesions were analyzed before intervention (29 patients, mean age 61 /- 9 years, 5 women and 24 men). Before and after IVUS examination, in tracoronary nitroglycerin 0.2 mg, was administered and two orthogonal angiographic views obtained. In 17 (57%) lesions the transducer of the IVUS catheter (radiopaque) could be gently advanced for precise locat ion at the lesion site, and in every case the ultrasonic images reveal ed that the catheter was wedged into the plaque. In the remaining 13 l esions only the catheter tip but not the transducer could be located a t the lesion site. Baseline minimal luminal diameter was similar in th e crossed lesions and in lesions that prevented complete advancement o f the IVUS catheter (0.86 +/- 0.2 vs 0.82 +/- 0.2 mm, difference not s ignificant). Lesion characteristics could not predict the feasibility of the IVUS study. No complications resulted from the IVUS study. Quan titative angiography (automatic edge-detection system) revealed a sign ificant increment in minimal luminal diameter (0.84 +/- 0.2 vs 1.16 +/ - 0.3 mm, p < 0.001) and minimal luminal cross-sectional area (0.67 +/ - 0.4 vs 1.09 +/- 0.5 mm(2), p < 0.01) after passage of the IVUS cathe ter. The gain in minimal luminal diameter was more marked in lesions c ompletely crossed with the IVUS catheter (0.39 +/- 0.2 vs 0.23 +/- 0.2 mm, p < 0.05) and in lesions with more severe (less than or equal to 0.8 mm) baseline luminal narrowing (0.46 +/- 0.2 vs 0.25 +/- 0.2 mm, p < 0.05). Thus IVUS examination of severe coronary lesions with curren tly available equipment (4.8F catheters) is safe but not feasible in a ll patients. The advancement of the IVUS catheter induces significant angiographic changes (a Dotter effect), consistent with plaque remodel ing, that should be taken into account in the interpretation of ultras onic images.