Randomized comparison of ultrasound surveillance and clinical monitoring on arteriovenous graft outcomes.

Arteriovenous graft thrombosis is a frequent event in hemodialysis patients, and usually occurs in grafts with significant underlying stenosis. Regular surveillance for graft stenosis, with pre-emptive angioplasty of significant lesions, may improve graft outcomes. This prospective, randomized, clinical trial allocated 126 hemodialysis patients with grafts to either clinical monitoring alone (control group) or to regular ultrasound surveillance for graft stenosis every 4 months in addition to clinical monitoring (ultrasound group). The two randomized groups were closely matched with respect to demographic, clinical, and graft characteristics, with the exception of a lower frequency of diabetes in the ultrasound group. The primary outcome was graft survival, and the secondary outcome was thrombosis-free graft survival. The frequency of pre-emptive graft angioplasty was 64% higher in the ultrasound group than in the control group (1.05 vs 0.64 events per patient-year, P<0.001), whereas the frequency of thrombosis was not different (0.67 vs 0.78 per patient-year, P=0.37). The median time to permanent graft failure was similar between the two groups (38 vs 37 months, P=0.93). Likewise, the median time to graft thrombosis or failure did not differ (22 vs 25 months, P=0.33). There was no significant association between diabetes and time to graft failure (P=0.93) or time to graft thrombosis or failure (P=0.88). In conclusion, the addition of regular ultrasound surveillance for graft stenosis to clinical monitoring increases the frequency of pre-emptive angioplasty, but may not decrease the likelihood of graft failure or thrombosis.

Hemodialysis access graft stenosis: US detection.

PURPOSE: To prospectively evaluate the sensitivity of ultrasonography (US) in diagnosing stenosis of hemodialysis access grafts and their drainage veins in patients clinically suspected of having graft dysfunction. MATERIALS AND METHODS: Thirty-eight patients in whom dysfunction of their hemodialysis access grafts was suspected underwent both Doppler US and angiography. Gray-scale and color US were combined with spectral analysis of the graft, anastomoses, and venous outflow. Flow velocity at anastomoses and suspected stenotic areas was measured. The volume of flow in the graft was also measured. The prospective US criterion for diagnosis of stenosis was a focal twofold or higher elevation of peak systolic velocity (PSV) compared with the PSV immediately upstream. A blinded angiographic evaluation of the graft and drainage veins followed US. Angiographic diagnosis of stenosis required at least 50% narrowing in luminal diameter. US and angiographic results were then compared. RESULTS: Angiography allowed diagnosis of 43 stenoses in 34 patients. US depicted 92% (37 of 40) of these stenoses, with a 94% positive predictive value for any individual patient. Focal 2- to 2.9-times PSV elevation was associated with 75% or greater stenosis. Graft flow volume and resistive index change did not correlate with stenosis. CONCLUSION: US reliably depicts stenoses of hemodialysis access grafts and drainage veins in a clinically selected population when PSV criteria are used.

Anatomic distribution of pulmonary emboli at pulmonary angiography: implications for cross-sectional imaging.

PURPOSE: To determine how often emboli detected angiographically in peripheral pulmonary arterial branches would be missed with cross-sectional imaging. MATERIALS AND METHODS: Seventy-nine of 88 consecutive pulmonary angiograms interpreted as positive for pulmonary emboli were reviewed retrospectively to detect pulmonary emboli. Three angiograms interpreted as negative when reviewed retrospectively were excluded. Findings of 76 angiograms in 76 patients (32 men, 44 women; aged 19-85 years) were correlated with the results of scintigraphy (n = 72) and Doppler ultrasound (n = 60), clinical presentation (n = 76), and follow-up with chart review (n = 72). RESULTS: Two hundred five emboli were identified. Nineteen patients had solitary emboli. Sixty emboli were in the upper lobes. The largest arterial branch with pulmonary embolism was lobar in 14 patients, segmental in 38, subsegmental in 20, and smaller in three. CONCLUSION: If cross-sectional imaging can depict emboli in only segmental and larger arterial branches, then emboli in 23 of 76 patients (30%) would have been missed with cross-sectional imaging.

Safety of pulmonary angiography in the 1990s.

PURPOSE: To examine the safety of pulmonary angiography with low-osmolar contrast material and modern angiographic techniques and to analyze periprocedural complications with respect to potential predictors. PATIENTS AND METHODS: A retrospective review was conducted of data from 547 consecutive patients who underwent pulmonary angiography. Minor and major complications were analyzed by using several clinical parameters. RESULTS: There were five major (0.9%) and 26 minor complications (4.8%). Eleven of the 26 minor complications were contrast-induced nephrotoxicity. There were no periprocedural deaths. Patients with complications had an increased incidence of coexistent pulmonary morbidities and were of a poorer physical status according to the American Society of Anesthesiology criteria. Moderate to severe pulmonary hypertension was correlated with major complications. Age, volume of contrast material used, and presence of pulmonary embolism were not correlated with complications. CONCLUSION: Pulmonary angiography is a safe procedure with an acceptable complication rate. These findings should be considered in the selection of an imaging method for the diagnosis of pulmonary embolism.

Accuracy of DSA in the evaluation of patency of infrapopliteal vessels.

PURPOSE: To evaluate the accuracy of intraarterial digital subtraction angiography (DSA) in the demonstration of patent infrapopliteal vessels. PATIENTS AND METHODS: One-hundred sixty-five arteriograms were obtained in 153 consecutive patients prospectively enrolled to evaluate lower extremity ischemia. In 86 cases a follow-up angiogram of the infrapopliteal vessels was obtained during surgery or after endovascular intervention (n = 57). Twenty-nine arteriograms were followed by surgical exploration of the infrapopliteal vessels. Standard angiographic technique was performed with intraarterial DSA of the most symptomatic foot. Visualization of distal vessels was compared with intraoperative or postintervention imaging or with the results of surgical exploration. RESULTS: Of the 57 procedures after which either intraoperative or post-endovascular intervention angiography was performed, DSA results were equivalent in 47 (82%) and worse in five (9%). When individual vessels were evaluated, the sensitivity of DSA in the identification of patent named vessels was 95%, and the specificity was 92%. Among 29 cases with a surgical standard of reference, 28 patients underwent bypass to a vessel correctly identified as patent at DSA; one patient was incorrectly identified as having no patent named vessels. CONCLUSION: Intraarterial DSA is accurate and reliable in the assessment of patency in infrapopliteal vessels before surgery or endovascular intervention in patients with infrainguinal atherosclerotic disease.

Screening mammography in 350 women with breast implants: prevalence and findings of implant complications.

OBJECTIVE: A series of screening mammograms in asymptomatic women with breast implants was reviewed to determine the prevalence of clinically silent sequelae of breast augmentation and to analyze the mammographic findings. MATERIALS AND METHODS: The screening mammograms of 350 consecutive women with implants were reviewed retrospectively by experienced mammographers. Any women who reported problems had a diagnostic examination and therefore were not included in our sample. Mammographic features of sequelae specific to implantation such as development of a fibrous capsule, periprosthetic calcification, implant herniation, and silicone leaks were tabulated. Additionally, modified compression (push-back) views, when obtained, were evaluated for their usefulness. RESULTS: Fibrous encapsulation of breast implants was seen in 257 (73%) of 350 women. Periprosthetic calcification was seen in 90 (26%), and 60 women (17%) had implant herniations. Sixteen women (5%) had implant failure as evidenced by silicone leak. Two of these women had bilateral implant failures. Surgical confirmation was attainable in only five of 16 women. Analysis of modified compression views demonstrated an overall improvement in visualization of breast tissue with this technique. Although the sample size is small, there was a significant increase in the amount of breast tissue seen with push-back views in women with submuscular implants. CONCLUSION: Our analysis revealed a wide range of mammographic findings in this group of asymptomatic women with breast augmentation. Especially worrisome is the 5% prevalence of unsuspected silicone extravasation. Additionally, we have demonstrated the usefulness of push-back views in this screening group, especially in women with submuscular implants.