[Intravascular echography].

Abstract

Intravascular ultrasound (IVUS) is an imaging method which uses one or several ultrasound transducers at the tip of catheters to visualize the morphology of arteries. IVUS was developed to provide precise information not only about arterial stenoses, but also about atherosclerotic lesions and lesions of the vessel wall. Indications for IVUS are currently being developed. One application is for the evaluation of disease of the common trunk when a doubt persists after angiography. Ambiguous lesions on angiography, particularly situated at coronary bifurcations, can also be clarified by IVUS. The precise evaluation of the real extent of atherosclerosis by IVUS makes it an ideal tool for clinical trials of regression of coronary disease. It also provides a better understanding of the apparent paradox between the minimal reduction of atheromatous plaques on angiography and the dramatic reduction of coronary events. IVUS is extremely useful to elucidate the mechanisms and complications of percutaneous interventional procedures. For example, IVUS allows a better understanding of restenosis after angioplasty (whether it is due to intimal proliferation or to vascular remodelling), elastic recall and sudden occlusion. In view of the large atheromatous mass visible on IVUS at the dilated site even after an angiographically adequate operation, insufficient angioplasty can be considered to be the third mechanism contributing to restenosis. This finding has important clinical implications, as ultrasound guidance could possibly result in better short-term and medium-term results of angioplasty. IVUS could also allow better selection of the type of operation in these patients. IVUS is also useful to facilitate adequate deployment of coronary stents, as angiographic criteria predicting ultrasonographically adequate expansion of the stent have still not been developed. By complementing angiography for the diagnosis of atheromatous disease and by monitoring percutaneous coronary operations, the role of IVUS as a clinically useful tool should continue to grow over the next few years.