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

Intravascular ultrasound (IVUS) imaging of the coronary arteries has recently been introduced for the study of coronary lesions, but the angiographic effects produced by an IVUS examination before coronary angioplasty are unknown. Accordingly, the feasibility of and the potential angiographic changes caused by IVUS study (4.8F catheter) of severe coronary 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, intracoronary 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 location at the lesion site, and in every case the ultrasonic images revealed that the catheter was wedged into the plaque. In the remaining 13 lesions only the catheter tip but not the transducer could be located at the lesion site. Baseline minimal luminal diameter was similar in the crossed lesions and in lesions that prevented complete advancement of the IVUS catheter (0.86 +/- 0.2 vs 0.82 +/- 0.2 mm, difference not significant). Lesion characteristics could not predict the feasibility of the IVUS study. No complications resulted from the IVUS study. Quantitative angiography (automatic edge-detection system) revealed a significant 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 catheter. The gain in minimal luminal diameter was more marked in lesions completely 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 currently available equipment (4.8F catheters) is safe but not feasible in all patients. The advancement of the IVUS catheter induces significant angiographic changes (a Dotter effect), consistent with plaque remodeling, that should be taken into account in the interpretation of ultrasonic images.