Intravascular ultrasound (IVUS) in patients with peripheral arterial occlusive disease (PAOD)

The new method of intravascular ultrasound (IVUS) permits an exact documentation of the pathomorphology of diseased arteries in a two-dimensional cross section image. Exact quantification of the vessel transverse diameters is achiveable. The different ultrasonic properties of fat, connective tissue and calcified tissue allow evaluation of intimal plaque composition. Thrombotic arterial occlusions can be detected. First experiences with IVUS prove, that this method is clearly superior to contrast arteriography and transcutaneous ultrasound, in terms of characterization and quantification of the extent of vessel wall disorders. Distinct structures, such as dissecting membranes or intimal flaps, which may escape arteriographic detection, are clearly visualized by IVUS. False adjustment of the physical parameters of the ultrasonic beam and non coaxial orientation of the ultrasound catheter within the vessel lead to false quantification of the transverse vessel diameters and to over- or underestimation of the echodensity and as a consequence of the intimal plaque composition. Simultaneous imaging of neighbouring arteries, veins or arterial branches allow longitudinal orientation within the vessel. Exact orientation however is only provided by simultaneous fluoroscopy. The present study demonstrates the value of IVUS as a guiding method of transcutaneous interventional procedures. The advantage could be an optimal selection of the recanalizing technique, appropriate to the arterial lesion. The result of interventional therapy can be documented immediately. Furthermore specific injuries of the vessel wall, leading to additional interventions and influencing short and long-term prognosis, can be imaged with high accuracy.