Clinical utility of negative contrast intravascular ultrasound to evaluateplaque morphology before and after coronary interventions

Although intravascular ultrasound (IVUS) is used for evaluation of plaque v olume and lumen size as well as detection of vessel wall structures after c atheter-based interventions, differentiation between the lumen and plaque s tructures can be difficult. This study attempted to evaluate the efficacy o f negative contrast IVUS imaging for assessment of vessel wall morphology a fter coronary interventions. IVUS studies were performed in 67 lesions in 6 6 patients before and after coronary interventions, After the baseline ultr asound imaging run, warm 5% glucose solution was injected manually through the guiding catheter into the coronary artery to washout blood from the lum en to avoid speckled reflections from red blood cells (negative contrast). Quantitative measurements were obtained and plaque morphology wets assessed for the presence and extent of medial dissections and intimal flaps. There was no difference in each quantitative parameter between baseline images a nd negative contrast images, The vessel wall boundary was clearly delineate d from the lumen, which was defined as effective negative contrast in 51 of 67 lesions (76%). The baseline images revealed plaque dissection in 9 lesi ons (18%) and an intimal flap in 13 lesions (25%). In addition, 4 dissectio ns (8%) and 16 intimal flaps (31%) were visualized during the infusion of n egative contrast. Additional treatment was performed in 4 lesions (8%) base d on the images with negative contrast. Negative contrast IVUS was more sen sitive in demonstrating a plaque fracture than were baseline images. This m ethod is useful for enhancing the diagnostic capability of IVUS imaging and may influence the decision-making process during interventional procedures . (C)1999 by Excerpta Medica, Inc.