Use of intravascular ultrasound in endovascular repair of abdominal aortic aneurysm

Introduction

Endovascular repair of abdominal aortic aneurysms (EVAR), although less invasive than surgical repair, is associated with exposure of both patients and the operating team to ionizing radiation, which may lead to the development of malignancies and eye problems [1–3]. Another disadvantage of EVAR is the use of intra-arterial iodinated contrast agents, which may lead to contrast-induced nephropathy [4]. Patients undergoing EVAR are also exposed to iodinated contrast agents during pre-interventional and post-interventional computed tomography angiography (CTA). Compared to patients who underwent open repair of the abdominal aortic aneurysm (AAA), renal function significantly deteriorated over the years in patients who underwent EVAR [5]. Thus, all techniques and strategies to reduce the exposure to radiation and contrast agents may further increase the safety of EVAR and extend its applicability. Intravascular ultrasound (IVUS) provides a real-time 360-degree image of the transverse section of the vessel. It enables precise measurement of the vessel, as well as its lumen diameter and surface. IVUS allows, to some extent, visualization of extraluminal adjacent structures within the imaging diameter. The use of a calibrated catheter allows to measure the distance between ultrasonographic anatomic vascular landmarks, such as vessel bifurcations or confluences, orifices of vascular branches and vessel crossing points, as well as between pathologic lesions such as stenosis or dilatation. Thanks to the use of automatic pull-back, it is possible to precisely measure the length of the vessel or vessel lesion. Without automatic pull-back, but using calibrated catheters, the length can also be measured using manual pull-back with an accuracy of 1 cm. The purpose of this article is to describe the application of IVUS in EVAR.

Selection of equipment and technique of intravascular ultrasound of abdominal aorta

Two types of transducers are used in IVUS catheters, mechanical and digital. In the case of a mechanical transducer, a single element rotates at a very high speed within the catheter tip. In the case of a digital transducer, there is an electronically switched multi-element array system. The advantage of the rotational transducer is very high frequency, up to 45 MHz, which translates into very high image resolution. However, high frequency is balanced by the limited penetration depth and small imaging diameter. Therefore, in...


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