Intravascular ultrasonography allows accurate assessment of abdominal aortic aneurysm: An in vitro validation study

AbstractObjective: The objective of this study was to acquire insight into the interpretation of intravascular ultrasound images of the abdominal aorta and to assess to what extent this technique can provide useful parameters for the endovascular treatment of patients with abdominal aortic aneurysm. Study Design: This was a descriptive study. Methods: Fifteen abdominal aortic specimens (normal, atherosclerotic, or aneurysmal) were studied. Ultrasonic images and corresponding histologic sections were compared for vessel wall characteristics, lesion morphologic characteristics, and lumen diameter. The length of the aneurysm and the length of the proximal and distal neck were measured and compared with external measurements. Tomographic images were reconstructed to a three-dimensional format. Results: Normal aortic wall was seen as a two- or three-layered structure corresponding with intima, media, and adventitia. A distinction could be made among fibrous lesion, calcified lesion, and thrombus and between normal and aneurysmal aorta. Correlation between the histologic specimens and intravascular ultrasonography for lumen diameter measurements was high (r = 0.93; p < 0.001). In a similar fashion, correlation between external measurements and intravascular ultrasound measurements on the length of the aneurysm and its proximal and distal neck was high (r = 0.99; p < 0.001). Three-dimensional analysis enhanced interpretation of the tomographic images by visualizing the spatial position of anatomic structures and contributed to understanding the shape and dimensions of the aneurysm. Conclusions: Intravascular ultrasonography provides accurate information on the vessel wall, lesion morphologic characteristics, and quantitative parameters of the abdominal aorta. Spatial information supplied by three-dimensional analysis contributes to a more realistic interpretation of the tomographic images. (J Vasc Surg 1998;27:347-53.

Stent placement for treatment of renal artery stenosis guided by intravascular ultrasound

PURPOSE: To study the impact of intravascular ultrasound (IVUS) during renal artery stent placement. MATERIALS AND METHODS: Patients (n = 22) with atherosclerotic renal artery stenosis were studied with IVUS after predilation and after angiographically successful stent deployment (diameter stenosis < 10%). After predilation, IVUS was used to assess whether the balloon size selected angiographically was correct (discrepancy balloon- reference lumen diameter < 20%). After stent placement, IVUS images were assessed for (i) complete stent-vessel wall apposition; (ii) complete stent expansion (discrepancy stent-reference lumen diameter < 20%), and (iii) complete lesion covering by the stent. Modification based on IVUS included selection of a larger balloon, additional dilation, and placement of a second stent. Clinical outcome was based on blood pressure, amount of antihypertensive drugs, and glomerular filtration rate during follow-up of 3 months. RESULTS: Stent placement and ultrasound imaging were completed successfully in 18 patients. After predilation, IVUS warranted the use of a larger balloon in five patients. After stent placement, incomplete stent apposition (n = 1), discrepancy between stent and reference lumen diameter (n = 3), and lesion distal to the stent (n = 2) seen on IVUS were treated with additional dilation in five patients and with a second stent in one patient. A larger balloon was used in three patients. Mean blood pressure and amount of antihypertensive drugs decreased (P < .05). CONCLUSIONS: In a number of patients, IVUS monitoring during renal artery stent placement resulted in additional lumen enlargement not considered necessary at angiography

In-vitro validation, with histology, of intravascular ultrasound in renal arteries

Objective. To investigate the feasibility of using intravascular ultrasound to characterize normal and diseased renal arteries. Materials and methods. Forty-four renal artery specimens from 21 humans, removed at autopsy, were studied with intravascular ultrasound in vitro. From each vascular specimen, two to four sets of corresponding intravascular ultrasound images and histologic sections were subjected to qualitative analysis. The renal arterial wall was considered normal by intravascular ultrasound when the wall thickness (intima and media) was 0.5 mm or less. On intravascular ultrasound imaging, a distinction was made between bright lesions with or without peripheral shadowing (i.e. calcification). Histological sections were examined and fibromuscular lesions were scored with or without calcifications. Quantitative analysis of a multitude of intravascular ultrasound cross-sections (interval 5 mm) included assessment of the lumen area, vessel area, plaque area and percentage area obstructed. The target site (smallest lumen area) was compared with a reference site (largest lumen area before the first major side branch). Results. Of the 130 corresponding intravascular ultrasound images and histologic sections analysed, 55 were normal and 75 presented a bright lesion on ultrasound; in 31 lesions, peripheral shadowing was involved. The sensitivity of the intravascular ultrasound in detecting calcifications was 87%, and the specificity was 89%. Lumen area reduction at the target site was associated with vessel and plaque area enlargement in eight specimens, with plaque area enlargement in 12 specimens and with a vessel area reduction in 21 specimens

Stent placement for renal arterial stenosis: Where do we stand? A meta- analysis

PURPOSE: To perform a meta-analysis of renal arterial stent placement in comparison with renal percutaneous transluminal angioplasty (PTA) in patients with renal arterial stenosis. MATERIALS AND METHODS: Studies dealing with renal arterial stent placement (14 articles; 678 patients) and renal PTA (10 articles; 644 patients) published up to August 1998 were selected. A random- effects model was used to pool the data. RESULTS: Renal arterial stent placement proved highly successful, with an initial adequate performance in 98% and major complications in 11%. The overall cure rate for hypertension was 20%, whereas hypertension was improved in 49%. Renal function improved in 30% and stabilized in 38% of patients. The restenosis rate at follow-up of 6- 29 months was 17%. Stent placement had a higher technical success rate and a lower restenosis rate than did renal PTA (98% vs 77% and 17% vs 26%, respectively; P < .001). The complication rate was not different between the two treatments. The cure rate for hypertension was higher and the improvement rate for renal function was lower after stent placement than after renal PTA (20% vs 10% and 30% vs 38%, respectively; P < .001). CONCLUSION: Renal arterial stent placement is technically superior and clinically comparable to renal PTA alone