Transrenal fixation of aortic stent-grafts for the treatment of infrarenal aortic aneurysmal disease.

PURPOSE: We evaluated our early experience with the transrenal fixation of aortic stent-grafts to determine the efficacy of this procedure and its effects on renal artery patency and hemodynamics. METHODS: Twenty-eight patients (22 men) had endoluminally placed modular bifurcated stent-grafts with a bare spring structure at the proximal end crossing the origin of both renal arteries; no patient with infrarenal fixation was included for analysis. The mean age of the patients was 75 +/- 7 years (range, 58-86 years); the mean aneurysm size was 5.8 +/- 0.8 cm (range, 4.7-7.2 cm). Eight patients had preoperative or intraoperative angiographic evidence of renal artery atherosclerotic disease, but only four vessels had luminal narrowing of 50% or greater. No complications were noted during stent-graft placement, and all patients have returned for follow-up visits, ranging from 1 to 12 months (mean follow-up, 6 +/- 4 months). Follow-up evaluations included clinical assessment, duplex ultrasound scan of the renal arteries and kidneys, and computed tomographic angiography. RESULTS: No evidence of lobular or sublobular perfusion defects of the renal parenchyma was detected postoperatively. Two patients exhibited postoperative changes in renal artery hemodynamics-one progressing from a 30% diameter reduction to a greater than 60% diameter stenosis at the 12-month follow-up visit and one with a normal renal artery preoperatively having elevated flow velocities indicative of a greater than 60% stenosis at the 1-month visit. Of 19 patients with normal preoperative renal function, only one has had persistently elevated serum creatinine levels. CONCLUSION: We conclude from this experience that the transrenal placement of open stents is safe and effectively excludes the aneurysm, potentially expanding the availability of this technique to more patients with a short infrarenal aortic neck. Long-term follow-up is essential to determine the overall efficacy of this technique and to identify potential effects on renal artery hemodynamics or kidney function.

Prevention by chemopreventive agents of azoxymethane-induced foci of aberrant crypts in rat colon.

Foci of aberrant crypts are putative preneoplastic lesions of colon cancer that can be detected in unsectioned colons stained with methylene blue. The ability of this assay to demonstrate chemopreventive activity was evaluated. Male Sprague-Dawley rats received two subcutaneous injections 1 week apart, of 15 mg/kg azoxymethane each. The animals started to receive the test agents in their diet 1 week prior to the first injection of azoxymethane and continuously until killed 5 weeks later. The number of foci of aberrant crypts induced by the treatment of azoxymethane was reduced from 228 foci/animal without any chemopreventive agent to 151 foci/animal by N-acetylcysteine; to 121 foci/animal by dehydroepiandrosterone; to 161 by alpha-difluoromethylornithine; and to 121 by 1,2-oxothiazolidine-4-carboxylate. The other agents (diallyl sulfide, ellagic acid and phenethyl isothiocyanate) did not significantly alter the number of foci/animal induced by azoxymethane. Animals that did not receive azoxymethane had an average of 0.72 foci/animal. Our results suggest that four of the tested agents might reduce azoxymethane-induced colon cancer, which requires confirmation. Further validation of the foci of aberrant crypt in the colon assay to screen chemicals for chemoprevention agents is warranted.

Limitations of electroencephalographic monitoring in the detection of cerebral ischemia accompanying carotid endarterectomy.

An analysis was undertaken of 458 consecutive carotid endarterectomies performed over 6 years with the patient under general anesthesia and with electroencephalographic monitoring. Seventy patients (15%) had electroencephalographic changes suggestive of ischemia with carotid clamping and had shunts placed. Ischemic encephalographic changes occurred in 26% of patients with an occluded contralateral carotid artery, 21% of patients with a prior stroke history, and 12% of patients with no stroke history and a patent contralateral carotid artery. Nineteen strokes (4.1%), nine transient deficits (2.0%), and one death (0.2%) occurred in the 458 endarterectomies in this experience. Ten of the 19 strokes and five of nine transient deficits were immediately apparent when patients awoke from anesthesia. Five of 10 patients with immediate strokes and all five patients with immediate transient deficits had no ischemic electroencephalographic changes during the procedure. Two other patients with immediate strokes initially had ischemic electroencephalographic changes after carotid clamping that reversed with increased blood pressure or shunting. Therefore 7 of 10 patients with immediate strokes and all 5 patients with immediate transient deficits had electroencephalographs unchanged from baseline at completion of the procedure, and thus deficits not manifest by operative electroencephalographic changes developed. Our data do not support the tenet that electroencephalographic monitoring will always predict neurologic deficits accompanying carotid endarterectomy.

A prospective study of the incidence and natural history of femoral vascular complications after percutaneous transluminal coronary angioplasty.

Over a 14-month period patients undergoing 144 percutaneous transluminal coronary angioplasty procedures were evaluated for the presence of complications at the femoral puncture site. After percutaneous transluminal coronary angioplasty each patient was examined by a surgeon, and then a color-flow duplex scan of the groin was obtained. On the initial scan eight pseudoaneurysms, three arteriovenous fistulas, one combined arteriovenous fistula-pseudoaneurysm, and one thrombosed superficial femoral artery were detected for a major vascular complication rate of 9%. Pseudoaneurysm formation was associated with the use of heparin after removal of the arterial sheath. Seven pseudoaneurysms (initial extravascular cavity size range 1.3 to 3.5 cm) were followed with weekly duplex scans, and all thrombosed spontaneously within 4 weeks of detection. The three patients with isolated arteriovenous fistulas were each followed for at least 8 weeks, and the arteriovenous fistulas persisted. Early surgical intervention for postcatheterization femoral pseudoaneurysms is usually unnecessary as thrombosis often occurs spontaneously. We would advocate an operative approach for pseudoaneurysms that are symptomatic, expanding, or associated with large hematomas. Iatrogenic femoral arteriovenous fistulas should be considered for elective repair, but this may be delayed for several weeks without adverse sequelae.

The carcinogenicity of trichloroethylene and its metabolites, trichloroacetic acid and dichloroacetic acid, in mouse liver.

Trichloroethylene (TCE) has previously been shown to be carcinogenic in mouse liver when administered by daily gavage in corn oil. The metabolism of TCE results, in part, in the formation of trichloroacetic acid (TCA) as a major metabolite and dichloroacetic acid (DCA) as a minor metabolite. These chlorinated acetic acids have not been shown to be genotoxic, although they have been shown to induce peroxisome proliferation. Therefore, we determined the ability they have been shown to induce peroxisome proliferation. Therefore, we determined the ability of TCE, TCA, or DCA to act as tumor promoters in mouse liver. Male B6C3F1 mice were administered intraperitoneally 0, 2.5, or 10 micrograms/g body wt ethylnitrosourea (ENU) on Day 15 of age. At 28 days of age, the mice were placed on drinking water containing either TCE (3 or 40 mg/liter), TCA (2 or 5 g/liter), or DCA (2 or 5 g/liter). All drinking waters were neutralized with NaOH to a final pH of 6.5-7.5. The animals were killed after 61 weeks of exposure to the treated drinking water (65 weeks of age). Both DCA and TCA at a concentration of 5 g/liter were carcinogenic without prior initiation with ENU, resulting in hepatocellular carcinomas in 81 and 32% of the animals, respectively. DCA and TCA also increased the incidence of animals with adenomas and the number of adenomas/animal in those animals that were not initiated with ENU. While 2.5 micrograms/g body wt ENU followed by NaCl in the drinking water resulted in only 5% of the animals with hepatocellular carcinomas, 2.5 micrograms/g body wt ENU followed with 2 or 5 g/liter DCA resulted in a 66 or 78% incidence of carcinoma, respectively, or, followed with 2 or 5 g/liter TCA, resulted in a 48% incidence at either concentration. None of the untreated animals had hepatocellular carcinomas. Therefore our results demonstrate that DCA and TCA are complete hepatocarcinogens in B6C3F1 mice.

A totally implanted venous access system for the delivery of chemotherapy.

The use of an Ommaya Capsule-Catheter System for the delivery of chemotherapy in cancer patients with inadequate peripheral veins has been studied over a 6-year period. Between 1978 and 1984, 76 Ommaya capsules were implanted in 68 patients, providing a collective experience of over 28,000 venous access days. Two patients were lost to follow-up. The results of the capsule-catheter system performance indicates a functional rate of over 90%. The complications included a 6.7% catheter occlusion rate, and a 2.7% capsule leakage rate. This accounts for an overall catheter related complication rate of 9.4%.