Silastic cuffed catheters for hemodialysis vascular access: thrombolytic and mechanical correction of malfunction.

Silastic cuffed catheters are assuming a greater role in providing long-term vascular access for hemodialysis patients. However, catheter thrombosis, fibrin sheath formation, and catheter malposition are recurrent problems that reduce extracorporeal flow rates and shorten catheter life. We reviewed 163 consecutive episodes of catheter malfunction that occurred in 121 catheters in 88 patients over a 3.5-year period. Intraluminal instillation of urokinase was successful in reestablishing an extracorporeal flow rate of > or = 300 mL/min in 74% of episodes. The 42 remaining episodes (26%) were radiologically evaluated. Two catheters required replacement for catheter kinking or insufficient catheter length. Two additional catheters were malpositioned; both were successfully repositioned with percutaneous techniques. A fibrin sheath was detected encasing the catheter in 38 instances. The fibrin sheath was successfully stripped from the distal portion of the catheter in 36 of the 38 instances. Using endoluminal thrombolytic therapy and percutaneous mechanical techniques, we have extended the mean survival for catheters intended for permanent vascular access to 12.7 months and have allowed 95% of the catheters inserted for temporary use to reach their use goal. Tunnel tract infection and catheter-mediated bacteremia were the primary reasons for catheter removal.

1992 ARRS Executive Council Award. Detection of deep venous thrombosis: prospective comparison of MR imaging with contrast venography.

OBJECTIVE: Preliminary reports have described the use of MR imaging for the detection of deep venous thrombosis. However, no prospective study comparing MR imaging with contrast venography (the gold standard) has been reported. Accordingly, we performed a prospective, blinded study of the efficacy of MR imaging in 61 consecutive patients with clinically suspected deep venous thrombosis. In cases of disagreement, additional testing was performed to determine the diagnosis. SUBJECTS AND METHODS: From June 1991 to February 1992, 61 patients with clinically suspected deep venous thrombosis were examined with venography and MR imaging. The average time between studies was 3 hr. In 21 of the 61 patients, the final diagnosis was deep venous thrombosis. RESULTS: For detection of deep venous thrombosis in the pelvis, the sensitivity of MR imaging was 100% (9/9) with a 95% confidence interval of 72-100% and the specificity was 95% (52/55) with a 95% confidence interval of 85-99%. In the thigh, the sensitivity (16/16) and specificity (43/43) were both 100% with 95% confidence intervals of 83-100% and 93-100%, respectively. In the calf, the sensitivity was 87% (13/15) with a 95% confidence interval of 60-98% and the specificity was 97% (36/37) with a 95% confidence interval of 86-100%. CONCLUSION: We found no statistically significant difference between MR imaging and contrast venography in the detection of deep venous thrombosis. This result suggests that MR imaging is at least as sensitive and specific as contrast venography in the detection of deep venous thrombosis.

CT arterial portography: causes of technical failure and variable liver enhancement.

OBJECTIVE: We studied the causes of technical failure and enhancement variability encountered during CT arterial portography. MATERIALS AND METHODS: CT arterial portograms and digital arteriograms were obtained via the superior mesenteric artery before partial liver resection in 43 patients with malignant tumors. These studies were reviewed for causes of technical failure and variable enhancement. RESULTS: Eleven (26%) of 43 procedures were technical failures. Causes of failure included aortic injection after catheter dislodgement (four), dense hyperenhancement associated with laminar flow in the portal vein produced by rapid venous return from a selective injection into a proximal branch vessel of the superior mesenteric artery (two), premature scanning beginning at the iliac crest (two), reflux into a replaced right hepatic artery (one), hepatic arterial enhancement via the pancreaticoduodenal arcade (one), and portal hypertension (one). Of the 32 remaining studies, 28 showed areas of parenchymal hypoenhancement or hyperenhancement. Causes of variable enhancement included impaired portal vein perfusion from mass effect of the tumor, laminar flow in the portal vein, and focal fatty infiltration. CONCLUSION: Technical failures and enhancement variability are common in CT arterial portography. Factors leading to technical failure include catheter choice and position, portal hypertension, and operator error.

Needle localization biopsy of occult lesions of the breast. Experience in 199 cases.

From January 1980 through June 1986, 199 percutaneous needle localizations for clinically occult breast lesions were performed at North Carolina Memorial Hospital. A retrospective analysis of the medical records, mammograms, operative notes, and pathology reports was undertaken to evaluate the success of this procedure. In our series, biopsy was prompted by abnormal calcifications in 27.1% of lesions, occult masses in 37.2%, and by a combination of occult masses and microcalcification in 35.7%. Overall, we had a yield of positive biopsies for cancer of 16.3%, with the yield improving from 12.3% in the earlier years of our study, to 18.7% in the latter years. Of the cancer cases detected, 89.7% were stage I. The localization procedure was successful in 95.9% of the cases. Analysis of our eight failures, along with a review of the literature, shows the major reasons for failure to be incomplete removal of areas with multiple calcifications, dislodgement of the needle, and problems resulting from lack of communication between the radiologist and surgeon. We conclude that the failure rate is low, the yield good, and needle localization a worthwhile procedure for localizing nonpalpable occult lesions.