Economic evaluations of interventions against influenza at workplaces: systematic review

BACKGROUND

The burden of influenza is mostly felt by employees and employers because of increased absenteeism rates, loss of productivity and associated direct costs. Even though interventions against influenza among working adults are effective, patronage and compliance to these measures especially vaccination are low compared to other risk groups.

AIMS

This study was aimed to assess evidence of economic evaluations of interventions against influenza virus infection among workers or in the workplace setting.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) reporting guideline for systematic reviews was followed. Three databases, PubMed, Web of Science and EconLit, were searched using keywords to identify relevant articles from inception till 25 October 2020. Original peer-reviewed papers that conducted economic evaluations of influenza interventions using cost-benefit, cost-effectiveness or cost-utility analysis methods focused on working-age adults or work settings were eligible for inclusion. Two independent teams of co-authors extracted and synthesized data from identified studies.

RESULTS

Twenty-four articles were included: 21 were cost-benefit analyses and 3 examined cost-effectiveness analyses. Two papers also presented additional cost-utility analysis. Most of the studies were pharmaceutical interventions (n = 23) primarily focused on vaccination programs while one study was a non-pharmaceutical intervention examining the benefit of paid sick leave. All but two studies reported that interventions against influenza virus infection at the workplace were cost-saving and cost-effective regardless of the analytic approach.

CONCLUSIONS

Further cost-effectiveness research in non-pharmaceutical interventions against influenza in workplace settings is warranted. There is a need to develop standardized methods for reporting economic evaluation methods to ensure comparability and applicability of future research findings.

Abstract P4-08-01: AMPK facilitates breast cancer cell survival by modulating microenvironmental stress

Recurrent and metastatic breast cancers are responsible for the majority of breast-cancer related deaths. These cancer cells are able to adapt to stressors within the tumor microenvironment including hypoxia, low nutrient levels, and chemotherapy-induced toxicities. Breast cancer cells can respond to these microenvironmental stressors through a variety of mechanisms, including cell cycle inhibition and metabolic alteration. Tumor cell survival is dependent on the ability to alter these mechanisms in response to stress. AMPK (AMP-activated protein kinase) is the main metabolic sensor of the cell, and both its expression and activity have been reported to be altered in breast cancer. Moreover, there are two isoforms of the catalytic subunit (α1 and α2), and differential functionality of these isoforms has been suggested. Using estrogen receptor-positive human breast cancer cell lines, we investigated the effect of differential AMPKα isoform expression on breast cancer cell survival. We found that over-expression of AMPKα2 in MCF-7 cells resulted in decreased ATP production in response to low glucose levels, while the knockdown of AMPKα2 in HCC1500 cells ablated this response to low glucose conditions. A similar difference in response was also seen when the cells were treated with a combination of nutrient stress and the estrogen receptor alpha (ERα) inhibitor, ICI182780. In response to this finding, we compared the glycolytic and oxygen consumption rates of our MCF-7 GFP and MCF-7 AMPKα2 cells. We found that in response to low glucose stress, AMPKα2 expressing MCF-7 cells maintained both a higher glycolytic rate and a higher oxygen consumption rate as compared to GFP cells. Furthermore, these cells seem to alter their cellular signaling in response to metabolic stress faster than GFP cells. To evaluate this differential response to microenvironmental stress in vivo, MCF-7 cells expressing either GFP or AMPKα2 were injected into athymic nude mice previously implanted with slow-release estradiol pellets. After one week, the estradiol pellets were removed to induce cellular dormancy for thirty days. Analysis of tumors at this time indicated that more of the AMPKα2 expressing cells survived estradiol deprivation than did the control cells. Analysis of proliferation by Ki67 staining indicated that the GFP cells maintained proliferation during deprivation, while AMPKα2 cells were largely negative for proliferation. ApoTag staining revealed a similar trend for apoptotic cells. This suggests that an inability to control cell cycle resulted in a decreased survival of the GFP cells under estradiol deprivation. Following the deprivation period, estradiol pellets were re-implanted and residual dormant tumors resumed growth. AMPKα2 tumors grew to roughly double the size of GFP tumors. Interestingly, AMPKα2 tumors had a higher number of mitotic events than did GFP tumors as visualized by Ki67 staining. This could be due to more viable cells being present following estradiol deprivation. We conclude that the expression of AMPKα2 promotes long-term breast cancer survival in estrogen-sensitive cells, due to their increased ability to sense and respond to changes in their microenvironment, which therefore increases their chances for survival.

Citation Format: Sullivan KL, Kopsiaftis S, Phoenix KN, Fox MM, Tsurutani N, Vella AT, Claffey KP. AMPK facilitates breast cancer cell survival by modulating microenvironmental stress. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-08-01.

A randomized trial of varenicline (Chantix) for the treatment of spinocerebellar ataxia type 3

OBJECTIVE

The objective of this double-blind, placebo-controlled, randomized study was to evaluate the efficacy of varenicline (Chantix), a partial agonist at α4β2 neuronal nicotinic acetylcholine receptors used for smoking cessation, in patients with spinocerebellar ataxia (SCA) 3.

METHODS

Patients with genetically confirmed SCA3 were randomly assigned to receive either varenicline (4 weeks for titration and 4 weeks at a dose of 1 mg twice daily) or placebo. Outcome measures included changes in the Scale for the Rating and Assessment of Ataxia (SARA) scores at endpoint (8 weeks) compared with baseline, a timed 25-foot walk and 9-hole peg test, measurements of mood and anxiety, and adverse events.

RESULTS

Twenty patients with SCA3 (mean age = 51 ± 10.98 years; mean disease duration = 14 ± 9.82 years; mean SARA score = 16.13 ± 4.67) were enrolled in the study, and data on 18 patients were analyzed in period I. The most common side effect associated with varenicline was nausea. Improvements were noted in the SARA subsections for gait (p = 0.04), stance (p = 0.03), rapid alternating movements (p = 0.003), and timed 25-foot walk (p = 0.05) and Beck Depression Inventory scores (p = 0.03) in patients taking varenicline compared with those taking placebo at endpoint, with a trend toward improvement in the SARA total score (p = 0.06) in the varenicline group.

CONCLUSIONS

In this controlled study, varenicline significantly improved axial symptoms and rapid alternating movements in patients with SCA3 as measured by SARA subscores and was fairly well tolerated.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that varenicline improved the axial functions of gait, stance, and timed 25-foot walk but did not improve appendicular function, except for rapid alternating movements, in adult patients with genetically confirmed SCA3.

Evidence-based guideline update: treatment of essential tremor: report of the Quality Standards subcommittee of the American Academy of Neurology

BACKGROUND

This evidence-based guideline is an update of the 2005 American Academy of Neurology practice parameter on the treatment of essential tremor (ET).

METHODS

A literature review using MEDLINE, EMBASE, Science Citation Index, and CINAHL was performed to identify clinical trials in patients with ET published between 2004 and April 2010.

RESULTS AND RECOMMENDATIONS

Conclusions and recommendations for the use of propranolol, primidone (Level A, established as effective); alprazolam, atenolol, gabapentin (monotherapy), sotalol, topiramate (Level B, probably effective); nadolol, nimodipine, clonazepam, botulinum toxin A, deep brain stimulation, thalamotomy (Level C, possibly effective); and gamma knife thalamotomy (Level U, insufficient evidence) are unchanged from the previous guideline. Changes to conclusions and recommendations from the previous guideline include the following: 1) levetiracetam and 3,4-diaminopyridine probably do not reduce limb tremor in ET and should not be considered (Level B); 2) flunarizine possibly has no effect in treating limb tremor in ET and may not be considered (Level C); and 3) there is insufficient evidence to support or refute the use of pregabalin, zonisamide, or clozapine as treatment for ET (Level U).

Practice Parameter: treatment of nonmotor symptoms of Parkinson disease: report of the Quality Standards Subcommittee of the American Academy of Neurology

OBJECTIVE

Nonmotor symptoms (sleep dysfunction, sensory symptoms, autonomic dysfunction, mood disorders, and cognitive abnormalities) in Parkinson disease (PD) are a major cause of morbidity, yet are often underrecognized. This evidence-based practice parameter evaluates treatment options for the nonmotor symptoms of PD. Articles pertaining to cognitive and mood dysfunction in PD, as well as treatment of sialorrhea with botulinum toxin, were previously reviewed as part of American Academy of Neurology practice parameters and were not included here.

METHODS

A literature search of MEDLINE, EMBASE, and Science Citation Index was performed to identify clinical trials in patients with nonmotor symptoms of PD published between 1966 and August 2008. Articles were classified according to a 4-tiered level of evidence scheme and recommendations were based on the level of evidence.

RESULTS AND RECOMMENDATIONS

Sildenafil citrate (50 mg) may be considered to treat erectile dysfunction in patients with Parkinson disease (PD) (Level C). Macrogol (polyethylene glycol) may be considered to treat constipation in patients with PD (Level C). The use of levodopa/carbidopa probably decreases the frequency of spontaneous nighttime leg movements, and should be considered to treat periodic limb movements of sleep in patients with PD (Level B). There is insufficient evidence to support or refute specific treatments for urinary incontinence, orthostatic hypotension, and anxiety (Level U). Future research should include concerted and interdisciplinary efforts toward finding treatments for nonmotor symptoms of PD.

Selective internal radiation therapy (SIRT) as salvage therapy for uveal melanoma (UM) hepatic metastases

9066

Background: The liver is the first site of metastasis in >80% of patients with UM. Transarterial chemoembolization (TACE) has been used to control hepatic metastases, however, patients eventually progress through or experience complications related to TACE. We report our results using SIRT as salvage therapy for patients with UM liver metastases who are no longer candidates for TACE. Methods: Patients with UM liver metastases previously treated with TACE were treated with SIRT. Patients were followed 1-month post-SIRT for acute toxicity then every 3 months for tumor response evaluation and for complications of delayed toxicity. Common Toxicity Criteria 3.0 (CTC) was used for toxicity assessment. Best radiographic tumor response was determined by MRI using RECIST criteria. Results: Five men and 7 women, ages 48–81 (median 65) with UM liver metastases were treated with SIRT after tumor progression post-TACE (n=9), complications of TACE (n=1) or patient preference (n=2). Pretreatment whole liver tumor burdens were as follows: <25% (n=10), 25–50% (n=1) and >50% (n=1). Patients had both hepatic lobes treated on separate occasions (n=7), one lobe (n=3) or whole liver (n=2) therapy. Treatment dose per patient was reduced by 25% due to prior TACE procedures. The mean total SIRT dose delivered was 1.0 GBq (0.62–1.47 GBq). Five patients had an increase in hepatic enzymes (Grade 1–4) at 1-month follow-up. No procedure related deaths or serious adverse events were experienced. Best tumor response was as follows: CR (n=0), PR (n=0), SD (n=8), PD (n=4), with a median follow-up of 7.8 months (1.0–16.0). The median time to liver progression was 7.0 months (1.0- 15.5). Nine of the 12 patients, including 2 patients with >25% pretreatment tumor burden, died due to progression of liver disease (n=6), extrahepatic disease (n=1) or both (n=2). Post-SIRT, median overall patient survival was 10.8 months (1.0–19.0). Three patients (ECOG 0 performance status) are still alive at 13.5–19.0 months (median 16.2 months) following SIRT. Conclusions: SIRT was safely used and showed a potential clinical benefit for patients previously treated with TACE. Further investigation is warranted to determine if SIRT should be employed as a first line therapy for patients with UM liver metastases.

No significant financial relationships to disclose.

Treatment of imbalance with varenicline Chantix(R): report of a patient with fragile X tremor/ataxia syndrome

We describe the case of a man with Fragile X tremor/ataxia syndrome, whose ataxia and imbalance improved with the use of varenicline (Chantix) and reverted to baseline 10 days after varenicline was discontinued. Varenicline was started as part of a smoking cessation program.

Social Security Disability Insurance (SSDI) in Parkinson's disease

OBJECTIVE

Parkinson's disease (PD) causes significant economic burden for patients and caregivers. Social Security Disability Insurance (SSDI) provides insurance to workers in the United States who have been gainfully employed, but who are no longer able to work due to a medical condition. We performed a descriptive pilot study that examined PD patients' experience with SSDI.

METHODS

PD patients who were diagnosed with PD prior to age 60 and were followed at an academic movement disorders center were consecutively invited to participate in a survey concerning their employment history and experience with SSDI.

RESULTS

All 68 invited patients participated in the study (mean age 58 years, mean disease duration 9.5 years). Eighty-two percent of patients felt that they were too disabled to work full time at a mean of 3.4 years after PD diagnosis. Patients applied for SSDI at a mean of 5 years after diagnosis, and two-thirds of PD patients who applied for SSDI obtained it on their first attempt. The primary debilitating symptom that subjectively contributed to work disability was fatigue (49% of patients). Patients who successfully acquired SSDI had extensive documentation of physician visits, and the aid of a disability lawyer.

CONCLUSIONS

Patients felt they were too disabled to work full time at a mean of 3.4 years after diagnosis. Those who applied for SSDI did so at a mean of 5 years after diagnosis. Patients who obtained SSDI awards had extensive documentation of medical records or the help of a disability lawyer.

Practice parameter: therapies for essential tremor: report of the Quality Standards Subcommittee of the American Academy of Neurology

BACKGROUND

Essential tremor (ET) is one of the most common tremor disorders in adults and is characterized by kinetic and postural tremor. To develop this practice parameter, the authors reviewed available evidence regarding initiation of pharmacologic and surgical therapies, duration of their effect, their relative benefits and risks, and the strength of evidence supporting their use.

METHODS

A literature review using MEDLINE, EMBASE, Science Citation Index, and CINAHL was performed to identify clinical trials in patients with ET published between 1966 and August 2004. Articles were classified according to a four-tiered level of evidence scheme and recommendations were based on the level of evidence.

RESULTS AND CONCLUSIONS

Propranolol and primidone reduce limb tremor (Level A). Alprazolam, atenolol, gabapentin (monotherapy), sotalol, and topiramate are probably effective in reducing limb tremor (Level B). Limited studies suggest that propranolol reduces head tremor (Level B). Clonazepam, clozapine, nadolol, and nimodipine possibly reduce limb tremor (Level C). Botulinum toxin A may reduce hand tremor but is associated with dose-dependent hand weakness (Level C). Botulinum toxin A may reduce head tremor (Level C) and voice tremor (Level C), but breathiness, hoarseness, and swallowing difficulties may occur in the treatment of voice tremor. Chronic deep brain stimulation (DBS) (Level C) and thalamotomy (Level C) are highly efficacious in reducing tremor. Each procedure carries a small risk of major complications. Some adverse events from DBS may resolve with time or with adjustment of stimulator settings. There is insufficient evidence regarding the surgical treatment of head and voice tremor and the use of gamma knife thalamotomy (Level U). Additional prospective, double-blind, placebo-controlled trials are needed to better determine the efficacy and side effects of pharmacologic and surgical treatments of ET.

Heart failure in Parkinson's disease: analysis of the United States medicare current beneficiary survey

OBJECTIVE

We sought to examine the prevalence of heart failure in elderly PD versus non-PD patients using a national sample of Medicare beneficiaries in the United States.

SCOPE

The prevalence of heart failure in elderly PD patients was 2.27 times that of non-PD patients (19.4% versus 8.7%, 95% CI = 1.43-3.60, p 0.0005), and remained twice as high after excluding patients with stroke and possible vascular parkinsonism.

CONCLUSIONS

In this cross-sectional study of a national Medicare database, heart failure occurred twice as frequently in elderly PD patients as in non-PD patients. Prospective studies are warranted to verify these findings.

Quantification of elastic recoil after balloon angioplasty in the iliac arteries

PURPOSE

Elastic recoil of the arterial wall has been shown to be responsible for a significant loss of luminal area after balloon angioplasty in the coronary arteries, but it has not been well studied in the peripheral arteries. Because elastic recoil depends on the presence of elastin in the arterial wall, and the amount of elastin varies by artery and proximity to the aorta, the importance of this response to angioplasty may be different in peripheral arteries. The purpose of this study is to document the degree of elastic recoil in the iliac arteries, and analyze variables that might influence the results.

MATERIALS AND METHODS

A series of 19 patients with 25 iliac artery stenoses underwent balloon angioplasty followed by placement of a Palmaz stent with the same-sized angioplasty balloon. The minimum luminal diameter of the lesion was measured before treatment, immediately after balloon angioplasty, and again after stent placement. The arterial diameter after stent placement was defined as the diameter of the inflated balloon. The degree of recoil was correlated with nine variables: patient age and sex, lesion location and length, lesion severity (as percent stenosis), the balloon:artery ratio, and three factors related to lesion morphology--complex versus simple, eccentric versus concentric, and calcified versus noncalcified.

RESULTS

Elastic recoil averaged 36% +/- 11% and ranged from 19% to 54% in this series of patients. The only variable that significantly influenced the degree of elastic recoil was the balloon:artery ratio (P =.039), which was directly related.

CONCLUSION

Elastic recoil is a significant limitation of balloon angioplasty in the iliac arteries. This study illustrates the importance of techniques that limit recoil, such as vascular stents, in angioplasty of the iliac arteries.

Tacrolimus-FK506 induced immunosuppression in gnotobiotic piglets

Tacrolimus (FK506), an inhibitor of calcineurin, is an immunosuppressive agent used in clinical trials of transplant patients. Although FK506 targets Ca(2+)-mediated T-cell signaling, phenotype(s) of the specific target cells and the corresponding cytokine pathways are not well known. In this study, the impact of FK506 on number and characteristic of T-cells in selected lymphoid tissues of gnotobiotic (GB) piglets was determined. FK506-treated GB piglets were compared with untreated GB and conventional piglets. The T-helper, cytotoxic, natural killer, double-positive, and activated T-cell populations were analyzed in suspensions of mononuclear cells isolated from thymus, mesenteric lymph nodes and peripheral blood. In vitro secretion of interleukin-8 and interferon-gamma in concanavalin A-stimulated lymphoid cell-cultures was measured by ELISA. Daily intramuscular treatment of GB piglets with 1mg/kg of FK506 from birth for 4 weeks resulted in lowered (P<0.05) in vitro secretion of interferon-gamma and interleukin-8. Moreover, depletions of MNC in systemic and mucosa-associated lymphoid tissues were observed in piglets treated with FK506. The depletions of mononuclear cells and low levels of interferon-gamma and interleukin-8 in piglets treated with FK506 were accompanied by lower proportion of CD3+, CD2+CD4+ and CD2+CD8+ T-cell phenotypes in peripheral blood but not in thymus and mesenteric lymph nodes. These results indicate that FK506-treatment causes immunosuppression in GB piglet, and this effect could be exploited further to study opportunistic pathogens in pig model.

The relationship of clinical and academic productivity in a university hospital radiology department

OBJECTIVE

The purpose of this study was to evaluate the relationship between clinical and academic productivity over a 2-year period in a university hospital radiology department.

MATERIALS AND METHODS

Clinical productivity, as determined by the number of total professional relative value units generated, was compared with academic productivity, which was determined by the number of published peer-reviewed articles, published non-peer-reviewed articles, published abstracts, and presentations delivered by each full-time clinical faculty member. The relationships of age, academic rank, administrative position, and division within the department were also assessed for their effect on relative value units and academic productivity.

RESULTS

We found a significant inverse relationship between relative value units and the number of published peer-reviewed articles, published abstracts, and presentations. Age, academic rank, and administrative responsibilities had no effect on the number of relative value units. Faculty in the neuroradiology and cardiovascular-interventional radiology divisions generated more relative value units than did other faculty members.

CONCLUSION

Faculty members with higher levels of clinical productivity showed significantly lower levels of academic productivity. This finding is consistent with the idea that increases in the clinical workload may diminish research output.

Accuracy and safety of carbon dioxide inferior vena cavography

PURPOSE

The purpose of this study was to assess the accuracy of carbon dioxide compared to iodinated contrast material for determining inferior vena cava (IVC) diameter prior to filter placement, and to assess the safety of CO2 when used for this purpose.

PATIENTS AND METHODS

Consecutive patients undergoing inferior vena cavography prior to filter placement were prospectively evaluated with use of both CO2 and iodinated contrast material. The diameter of the IVC was measured and compared in the same four locations in each patient for both agents. The diameter was corrected for magnification and pin-cushion distortion. The ability of CO2 to correctly classify IVC diameter as < or =28 mm or >28 mm, based on the IVC diameter with iodinated contrast material, was determined. A consensus panel assessed renal vein visualization with CO2 and iodinated contrast material. Blood pressure and arterial oxygen saturation were measured immediately before and after CO2 injection.

RESULTS

Among 30 patients, there was no significant difference in the measured diameter of the IVC with CO2 versus iodinated contrast material after correction for magnification and pin-cushion distortion. One of 30 patients (3.3%) in this study was misclassified as having an IVC < or =28 mm with CO2 when, in fact, the IVC diameter was >28 mm based on iodinated contrast material. This could be clinically significant for certain IVC filters. Forty-seven percent of renal veins identified on contrast venography were identified by CO2 vena cavography. There was no significant difference in the blood pressure or oxygen saturation values measured before and after CO2 injection. However, one patient with pulmonary artery hypertension did experience transient, symptomatic hypotension after CO2 injection.

CONCLUSIONS

In most patients, CO2 vena cavography accurately evaluated IVC diameter prior to filter placement. In 3.3% of patients, the discrepancy in measurements between CO2 and iodinated contrast material could be clinically significant, depending on the type of filter placed. CO2 was less accurate than iodinated contrast material in identifying renal veins. Although CO2 vena cavography is safe in the majority of patients, it should be used with caution in patients with pulmonary hypertension.

Intravascular ultrasound as an alternative to positive-contrast vena cavography prior to filter placement

PURPOSE

In a nonconsecutive series of patients, intravascular ultrasound (IVUS) was investigated for safety and efficacy as an alternative to positive-contrast vena cavography for evaluating the inferior vena cava (IVC) prior to filter placement.

MATERIALS AND METHODS

In a 6.5-year period, 30 patients (15 women, 15 men) ranging in age from 22 to 98 years old (mean, 56 years) underwent vena cava filter placement without conventional positive-contrast vena cavography, after IVUS evaluation of the IVC with use of a 6.2-F, 12.5- or 20-MHz monorail catheter system. The rationale for using IVUS included contraindications to iodinated contrast material in 14 patients with renal insufficiency and in four patients with previous life-threatening anaphylactoid reaction to iodinated contrast material; limitations to radiation exposure in four pregnant patients; and inability to otherwise image the IVC of eight morbidly obese patients who exceeded the weight limits of available angiographic equipment. IVUS completely replaced positive-contrast vena cavography, although not fluoroscopy in the four pregnant patients and in the 18 patients with contrast material contraindications. In two of the eight obese patients, IVUS was the only imaging modality.

RESULTS

In all 30 patients, IVUS successfully determined the patency of the filter delivery route veins and the vena cava, the absence of thrombus, the location of renal veins, the absence of anatomical variants, and the vena cava diameter at the desired filter deployment level. Successful filter placement was confirmed in all 30 patients either with plain film alone (n = 12), IVUS alone (n = 3), computed tomography alone (n = 1), external ultrasound alone (n = 1), IVUS and another imaging modality (n = 10), or by combinations of other imaging modalities (n = 3). There were no complications.

CONCLUSIONS

IVUS is a safe and effective alternative to conventional positive-contrast vena cavography for imaging the IVC prior to filter placement in patients with contraindications to iodinated contrast material or ionizing radiation.

Carbon dioxide as a contrast agent to guide vascular interventional procedures

OBJECTIVE

The purpose of this study was to assess the value and limitations of carbon dioxide (CO2) as a contrast agent to guide vascular interventional procedures.

SUBJECTS AND METHODS

Twenty-two adults underwent 26 vascular interventional procedures (21 arterial, five venous). We aimed to use only CO2 if possible because these patients had renal insufficiency (n = 21; mean creatinine level, 2.8 mg/dl) or were allergic to contrast material (n = 1). Arterial procedures performed included renal angioplasty or stent (n = 6), iliac angioplasty or stent (n = 5), infrainguinal angioplasty (n = 5), arterial bypass graft angioplasty (n = 3), and thrombolysis (n = 2). Venous procedures included transjugular intrahepatic portosystemic shunt recanalization (n = 3), angioplasty of the venous anastomosis of a thigh dialysis graft (n = 1), and angioplasty of the inferior vena cava (n = 1).

RESULTS

Twenty-five of the 26 procedures were successfully performed. Of the 26 procedures, eight required no iodinated contrast material and 11 required less than or equal to 20 ml of contrast material. CO2 proved to be inadequate for the remaining seven procedures. Iliac artery angioplasty or stent placement required an average of 9 ml of iodinated contrast material; infrainguinal angioplasty required an average of 22 ml of iodinated contrast material.

CONCLUSION

CO2 can be successfully used as a contrast agent in a variety of vascular interventional procedures. Such procedures can usually be performed in the iliac and infrainguinal arteries using minimal supplemental iodinated contrast material. However, CO2 failed to provide satisfactory guidance in half of the intraabdominal procedures in our study.

Profiles of healing and nonhealing Cryptosporidium parvum infection in C57BL/6 mice with functional B and T lymphocytes: the extent of gamma interferon modulation determines the outcome of infection

This study describes healing and nonhealing models of Cryptosporidium parvum infection with adult mice that have functional T and B lymphocytes. In our nonhealing model, mice on a C57BL/6 background which have a targeted disruption in the gamma interferon (IFN-gamma) gene (GKO mice) are utilized. C. parvum-infected GKO mice shed extremely high levels of oocysts and displayed overwhelming infection of the entire small intestine. The majority of these mice succumbed within 2 to 3 weeks due to severe acute infection and profound mucosal destruction. In our healing murine model, C57BL/6J mice treated with a single injection of the neutralizing anti-IFN-gamma monoclonal antibody XMG 1.2 prior to infection were used. These mice developed two peaks of oocyst shedding but were ultimately free of parasites on day 30 of infection. Again, the small intestine was the primary site of infection. Mesenteric lymph node (MLN) cells isolated from C. parvum-infected nonhealing GKO mice proliferated and secreted interleukin 2 (IL-2) but not IFN-gamma or IL-4 in response to ex vivo restimulation with intact C. parvum sporozoites or a C. parvum sporozoite antigen preparation. In contrast, parasite-specific MLN cells isolated from healing C57BL/6J mice secreted IL-2 and IFN-gamma but not IL-4. These results suggest that IFN-gamma, either directly or indirectly, is important for resistance to and resolution of cryptosporidiosis. Moreover, these models now allow the analysis of parasite-specific cell-mediated and humoral mucosal immune responses to determine what constitutes protective immunity to C. parvum.

Malignant biliary duct obstruction: long-term experience with Gianturco stents and combined-modality radiation therapy

PURPOSE

To evaluate the effect of combined-modality therapy including intraluminal iridium-192 on stent patency and survival in patients with malignant biliary obstruction treated with Gianturco stents.

MATERIALS AND METHODS

Twenty-two patients with unresectable biliary obstruction caused by cholangiocarcinoma (n = 11) or by secondary extrahepatic bile duct malignant tumors (n = 11) were treated with percutaneous biliary drainage followed by intraluminal Ir-192 wire placement (mean dose, 25 Gy) before insertion of Gianturco metal stents. Eleven patients also received external-beam radiation therapy, and 13 patients received chemotherapy. Patency was defined as absence of jaundice or cholangitis that necessitated hospitalization, or as seen on hepatobiliary scans. Survival was determined from the time of stent insertion after brachytherapy.

RESULTS

Patients with cholangiocarcinoma had extended mean stent patency of 19.5 months (range, 2-46 months) and mean survival of 22.6 months (range, 2-72 months). Patients with secondary malignant tumors had a mean patency of 4.8 months (range, 1.5-8 months) and a mean survival of 5.3 months (range, 2-9 months).

CONCLUSION

Radiation therapy including intraluminal Ir-192 appears to extend stent patency and survival in patients with inoperable cholangiocarcinoma treated with Gianturco metal stents compared with patients with other extrahepatic bile duct malignant diseases and patients treated without combined-modality therapy in other studies.

Chemical ablation of the gallbladder: is it feasible?

PURPOSE

Transcatheter ablation of the gallbladder has been attempted in animals and humans with a variety of chemical and physical agents. Initial in vitro experiments suggested sodium hydroxide and hydrogen peroxide were more effective sclerosants than previously reported chemical agents. A phase I trial of escalating concentrations of and exposure times to these agents was performed in vivo.

MATERIALS AND METHODS

Fourteen domestic pigs underwent cholecystostomy tube placement and cystic duct ligation. Two weeks later, sclerosis was performed with sodium hydroxide/ethanol solutions and hydrogen peroxide.

RESULTS

Sequential 15- or 30-minute exposures to 0.1 N solutions of sodium hydroxide in ethanol followed by 3% peroxide failed to completely eliminate the pig gallbladder epithelium in vivo; 0.5 N and 1.0 N sodium hydroxide in ethanol caused gross gallbladder hemorrhage, mural dissection, and one perforation. Although the gallbladder lumen was ablated, the gallbladder epithelium was not completely eliminated in any animal.

CONCLUSION

Chemical ablation of the pig gallbladder epithelium was not feasible in this experimental model.

Utility of intra-access pressure monitoring in detecting and correcting venous outlet stenoses prior to thrombosis

Vascular access thrombosis is a major problem for hemodialysis patients. Over 7.75 years, we performed intra-access venous pressure monitoring at zero dialyzer blood flow (VP0), correlated VP0 with access anatomy angiographically, and examined the effect of two levels of stenosis, 50% and > 65% luminal diameter reduction (% D) as selection criteria for referral and elective angioplasty or surgical revision upon access outcomes. Summary receiver outcome curves for absolute intra-access pressure (VP0) and intra-access pressure normalized for systemic pressure (VP0/systolic BP) were constructed to evaluate sensitivity and specificity and compared to recirculation and duplex color-flow Doppler. Access outcomes included thrombosis, revision, replacement, and angioplasty rates that were normalized per 100 patient years (100 pt-yrs). During the 7.75 year long study period totaling 832 patient-access years of risk, the percentage of prosthetic bridge grafts increased from 65% to 80%. SROC showed better sensitivity for normalized (VP0/systolic BP) than absolute intra-access pressure (VP0) in grafts. Recirculation had poor predictive power in prosthetic bridge grafts compared to VP0. Predictive power of recirculation was superior to VP0 in native arteriovenous fistulae. The angioplasty rate correlated inversely with the degree of luminal reduction used as selection criterion for referral for angioplasty or surgical revision. A strong inverse relationship between thrombosis rate and the angioplasty rate (R2 = 0.99) but not between thrombosis rate and the number of angiograms performed (R2 = 0.39) was noted. A consistent, yet evolving, intensive graft maintenance protocol produced a 70% decrease in the thrombosis rate, a 79% decrease in the access replacement rate, and an increase in the average age of patent usable vascular accesses from 1.97 to 2.98 years that was associated with a 13-fold increase in the angioplasty rate. We conclude that vascular access monitoring with VP0/systolic BP provides excellent selection criteria for angiographic referral. Intervention for stenotic lesions > 50% D using angioplasty or surgical revision markedly reduces thrombosis and access replacement rates.

Venography with carbon dioxide as a contrast agent

PURPOSE

The purpose of this study was to evaluate the feasibility, safety, and potential role of carbon dioxide (CO2) as a contrast agent for venography.

METHODS

Consecutive patients with contraindications to iodinated contrast agents or with unsatisfactory iodinated contrast studies underwent CO2 digital subtraction venography. The images were rated by three experienced angiographers. Image quality and complications were assessed.

RESULTS

Over a 14-month period, 66 vein segments were studied in 21 patients. There was good correlation between experienced angiographers on CO2 image quality (Ri = 0.80) and good agreement on diagnosis (k = 0.62). In 91% of the vein segments evaluated with C02 there was interobserver agreement on the diagnosis. Upper extremity veins were adequately imaged with CO2 alone in all (6/6) patients with contraindications to iodinated contrast. Following suboptimal iodinated contrast studies in six patients, CO2 produced significantly better quality upper extremity central vein images (p < 0.05). Pain following injection into peripheral veins was the only CO2-related complication. Inferior vena cava (IVC) filters were successfully deployed with CO2 alone in 78% (7/9) of patients; two required iodinated contrast.

CONCLUSIONS

Based upon initial experience, CO2 venography can be recommended in patients with contraindications to iodinated contrast or unsatisfactory iodinated contrast studies.

Treatment of pelvic abscesses and other fluid collections: efficacy of transvaginal sonographically guided aspiration and drainage

OBJECTIVE

The purpose of this study was to evaluate the clinical efficacy of transvaginal sonographically guided aspiration and drainage of pelvic fluid collections.

MATERIALS AND METHODS

Forty patients underwent transvaginal sonographically guided aspiration of a possible pelvic abscess (41 pelvic collections). In patients with clinical findings highly suggestive of infection, both purulent and nonpurulent collections were immediately drained via a catheter. In patients with clinical findings moderately suggestive of infection, nonpurulent collections were completely removed by aspiration and the aspirates were cultured; however, purulent collections were immediately drained via a catheter.

RESULTS

All collections were successfully accessed by transvaginal sonography. For 27 of the 41 collections, the aspirate was purulent (18 collections) or the patient's clinical findings were highly suggestive of infection (nine collections) and catheter drainage was performed. Seventeen of the 27 collections completely resolved and surgery was not required. Four of the 27 collections were in patients who had surgery for reasons other than persistent infected collection. For six of the 27 collections, catheter treatment was not successful and surgery was required. The overall success rate of catheter drainage was 78%. In the remaining 14 of the 41 collections, the aspirate was serous or serosanguineous, and the patient's clinical findings were moderately suggestive of infection. Cultures of aspirates of seven collections were positive for microorganisms. Eleven collections were successfully treated with antibiotics or no therapy was required (based on culture results); for three, surgery was required. Two complications occurred: one vaginal fistula after catheter drainage and one disruption of vaginal sutures after aspiration.

CONCLUSION

Transvaginal sonographically guided drainage is effective treatment of pelvic abscess, being either completely curative or temporizing in 78% of patients. Catheter treatment was unsuccessful and surgery was necessary in 22% of patients. For nonpurulent collections, catheter drainage is indicated only when clinical findings are highly suggestive of infection.

Chemical ablation of the gallbladder: evaluation of multiple agents in vitro

PURPOSE

To find a more effective chemical regimen for transcatheter ablation of the gallbladder in an in vitro model.

MATERIALS AND METHODS

Sectioned and whole pig gallbladders were exposed in vitro to 12 different chemical solutions at varying conditions of exposure time, pH, and temperature.

RESULTS

In the in vitro studies, 0.1 N and 1.0 N solutions of sodium hydroxide in water or ethanol and 3% hydrogen peroxide were the most effective sclerosant agents. Ethanol and hydrochloric acid failed to completely eliminate the epithelium from the gallbladder sections. Increasing exposure time from 10 to 20 minutes or increasing the temperature of the solutions from 37 degrees C to 50 degrees C did not alter these results. Sequential 15-minute exposures to 0.1 N sodium hydroxide in ethanol followed by peroxide completely eliminated the epithelium from whole gallbladders in vitro.

CONCLUSION

Alkaline solutions and hydrogen peroxide are more effective than ethanol alone, acids, or detergents in eliminating gallbladder epithelium in this model. Further evaluation of these agents in vivo is merited.

Arterial abnormalities following orthotopic liver transplantation: arteriographic findings and correlation with Doppler sonographic findings

OBJECTIVE

We studied the findings on conventional arteriography in patients who had suspected graft ischemia after orthotopic liver transplantation to determine the value of a single Doppler signal in predicting these lesions.

MATERIALS AND METHODS

We retrospectively reviewed selective visceral arteriograms with abnormal findings from 20 adults who had suspected graft ischemia after orthotopic liver transplantation and a single Doppler signal from the hepatic artery at the porta hepatis on sonograms obtained before arteriography. Arteriographic abnormalities were categorized according to morphology and location as follows: stenosis of recipient's hepatic artery, occlusion or stenosis of the transplanted extrahepatic artery, and occlusion or stenosis of the transplanted intrahepatic artery.

RESULTS

Twenty-three arteriographic abnormalities were detected: four recipient celiac axis stenoses, seven extrahepatic occlusions, nine extrahepatic stenoses, and two occlusions and one stenosis of the transplanted intrahepatic artery. Six of the extrahepatic occlusions, two of the extrahepatic stenoses, and none of the recipient artery stenoses or the intrahepatic occlusions or stenoses were correctly diagnosed on the basis of Doppler findings. One patient with both an extrahepatic stenosis and an extrahepatic occlusion was thought to have an intrahepatic occlusion, and two patients with mild (< 50%) extrahepatic stenoses and one with an intrahepatic occlusion were thought to have an extrahepatic occlusion.

CONCLUSION

A wide spectrum of abnormalities in the recipient's celiac axis or the transplanted arteries that may be associated with graft ischemia after orthotopic liver transplantation are often not detected or findings are misinterpreted on routine Doppler examination. In patients with suspected graft ischemia, visceral arteriography should be performed promptly to confirm the diagnosis and to allow early intervention.

Role of selective arteriography in the diagnosis of a ruptured middle colic artery aneurysm

A case of a ruptured middle colic artery is reported. The diagnosis was initially overlooked and eventually made by selective arteriography. Aneurysms of visceral arteries are rare and rupture of them even more infrequent. Awareness of this potentially fatal and treatable entity should enable early detection by selective visceral arteriography. The roles of embolization and surgery in the management of visceral aneurysms are discussed.

Fallopian tube recanalization in an unrestricted patient population

PURPOSE

To review the effectiveness of fallopian tube recanalization (FTR) when performed without restriction based on history or tubal condition.

MATERIALS AND METHODS

From October 1989 to July 1992 in 37 consecutive women, aged 22-44 years (mean, 35 years), 42 FTRs were performed (five patients each underwent two FTRs). Water-soluble contrast material and selective ostial salpingography and/or microcatheter technique were used exclusively. Eighty tubes were evaluated, since four patients had previously undergone unilateral salpingectomy. Sixty-three tubes (79%) were occluded at the outset of the procedure.

RESULTS

Complete recanalization was achieved in 45 of 63 (71%) occlusions. Adhesions were present in 25 of 80 (31%) tubes, salpingitis isthmica nodosa in 12 (15%), and hydrosalpinx in nine (11%). The 42 procedures resulted in 14 (33%) conceptions, nine (64%) of which involved pathologic tubes. Eleven intrauterine pregnancies resulted in five spontaneous first-trimester abortions, five full-term deliveries, and one continuing pregnancy.

CONCLUSION

Favorable conception and live birth rates can be achieved with FTR, despite a high prevalence of tubal disease.

Use of a Colapinto needle in US-guided transvaginal drainage of pelvic abscesses

The ultrasound-guided transvaginal approach offers a direct, nonsurgical means for drainage of deep pelvic abscesses. It is often difficult, however, to place drainage catheters through the vaginal wall by using routine Seldinger technique. The authors describe four recent drainage procedures facilitated through use of a Colapinto needle as a dilator. In two cases, the Colapinto needle also served as a stiffening cannula for the passage of a fascial dilator.

Exchange of an occluded nephroureteral stent by using a snare

Percutaneous retrograde nephroureteral stent exchange may be complicated by catheter occlusion with calcareous debris. When a guide wire cannot be passed through the catheter, a snare may be advanced over the stent into the renal pelvis, permitting withdrawal of the occluded stent while maintaining access for placement of a new stent. This procedure was performed successfully in a 73-year-old man.

Hemodynamics of failing dialysis grafts

Pressures were measured in the graft and the central vein during 104 consecutive angiographic examinations of failing hemodialysis grafts. Stenosis severity greater than 40% led to a statistically significant rise in graft pressure. In grafts in which all stenoses were of 40% or less severity, the systolic pressures in the venous and arterial limbs of the grafts were 31% +/- 16 and 45% +/- 17, respectively, of systemic systolic pressure. In grafts in which the highest grade of stenosis was greater than 40%, pressures in the venous and arterial limbs of the grafts were 53% +/- 25 and 75% +/- 24, respectively, of systemic systolic pressure. Graft thrombosis tended to occur at a higher degree of lumen reduction (but at similar pressures) with central vein stenoses compared with venous anastomotic stenoses. Dialysis graft pressures can help determine the hemodynamic importance of stenoses and the need for intervention. Percutaneous intervention should achieve arterial and venous limb pressures of less than 50% and 33% of systemic pressure, respectively.

Gallstone Lithotripsy: In Vitro Comparison of Fragmentation with a Tunable-Dye Laser and an Ultrasonic Wire

Large bile duct stones require fragmentation prior to extraction through the papilla or through a percutaneous tract. This can be attempted with dissolution therapy, crushing baskets, or lithotripsy. Lithotripsy can be accomplished safely and effectively with tunable-dye laser energy delivered through a flexible, 1-F optical fiber under endoscopic or fluoroscopic guidance, but laser technology is very costly. A prototype, flexible ball-tipped wire coupled to an ultrasonic generator via a piezoelectric crystal has been developed for sonolysis of atheroma and thrombus in humans. The purpose of this experiment was to compare human gallstone fragmentation in vitro with a tunable-dye laser and this prototype wire to see if the less expensive ultrasound device might provide an alternative to costly laser technology. Gallstones from 17 patients were subjected to lithotripsy in a water bath with each device until completely fragmented or 60 seconds had elapsed. Neither device effectively fragmented cholesterol stones under these conditions. The ultrasonic wire completely fragmented 57% of bilirubinate stones in 60 seconds. The tunable-dye laser completely fragmented 100% of bilirubinate stones in less than 35 seconds (P = .04). Tunable-dye laser lithotripsy appears superior to the ultrasonic device for percutaneous treatment of bile duct stones.

Intraarterial chemotherapy with limb-sparing resection of large soft-tissue sarcomas of the extremities

Fifteen patients with large (average, 15-cm), high-grade soft-tissue sarcomas of the extremities received prolonged selective intraarterial infusions of chemotherapeutic agents in an attempt to permit limb-sparing resection of these tumors, which would otherwise have required amputation. There were seven malignant fibrous histiocytomas, four liposarcomas, two fibrosarcomas, one leiomyosarcoma, and one rhabdomyosarcoma; 73% were grade III. Seven patients underwent two catheterizations, for a total of 22 infusions, which averaged 11.3 days each. There were four catheterization-related complications, including catheter occlusion or dislodgement in one patient each and two cases of arterial thromboembolism in patients in whom anticoagulant dose was not adequate. Both of the latter patients required thrombectomy; one developed gangrene, which precluded limb-sparing surgery. Thirteen of the 15 patients underwent limb-sparing resections, and two underwent amputations. No wound complications occurred. With a median follow-up of 36 months (mean, 34 months), life-table analysis indicates overall and disease-free survivals of 72% and 59%, respectively, at 2 years and 64% and 59% at 3 years. In comparison to other reported therapies, this technique permits limb salvage in most patients without the high wound complication rate associated with preoperative radiation therapy, with equivalent local disease control and survival.

The relationship between dialysis graft pressure and stenosis

RATIONALE AND OBJECTIVES

Pressure measurements during dialysis have been used to screen for venous outlet stenosis, but the relationship between the degree of stenosis and pressure has not been defined.

METHODS

To determine this relationship, failing or failed dialysis grafts (n = 34) were studied with angiography and pressure measurements from the segment of the graft near the arterial anastomosis.

RESULTS

By linear regression, the relationship between the highest grade stenosis in or central to the graft and pressure was as follows: percent stenosis = 55 systolic graft pressure/systolic blood pressure+13 (r = 0.75).

CONCLUSIONS

There is a positive correlation between the severity of stenosis and graft pressure, confirming the use of this measurement in screening for stenosis. It is hypothesized that this relationship is the result of progressive elimination of the normal pressure drop between the artery and arterial limb of the graft as the degree of stenosis increases.

Subclavian artery angioplasty proximal to a left internal mammary-coronary artery bypass graft: case report

Subclavian artery angioplasty is an established treatment for subclavian steal syndrome and arm ischemia caused by subclavian stenosis. We report a case of angina pectoris caused by a subclavian artery stenosis proximal to a left internal mammary-coronary artery bypass graft. Angioplasty was performed without complication and with complete relief of symptoms. Reactive hyperemia was induced in the forearm and hand with a blood pressure cuff prior to angioplasty to increase blood flow to the arm, and to reduce the chance of graft embolization. Repeat angiography 6 months later confirmed continued patency of the subclavian artery and the graft and reversal of the steal physiology. The patient remains symptom free 15 months after angioplasty.

Transhepatic laser lithotripsy of choledocholithiasis: initial clinical experience

Three patients with symptomatic intra- and extrahepatic choledocholithiasis who were not good candidates for retrograde endoscopy, surgery, or extracorporeal shock wave lithotripsy (ESWL) were treated successfully with endoscopically guided tunable dye laser lithotripsy via a 12-F transhepatic sheath. There were no complications secondary to the use of the laser. On the basis of this initial experience, transhepatic laser lithotripsy is a technically feasible and safe alternative when choledocholithiasis cannot be managed with retrograde endoscopy, ESWL, or surgery. Its role in the management of choledocholithiasis relative to other transhepatic techniques remains to be determined.

Successful percutaneous closure of a complex coronary-to-pulmonary artery fistula using a detachable balloon: benefits of intra-procedural physiologic and angiographic assessment

A 48-yr-old woman presented with a loud continuous precordial murmur and symptoms of fatigue. Color-flow doppler imaging and nuclear magnetic resonance imaging failed to show the cause of the murmur. Diagnostic catheterization showed a large left anterior descending coronary artery to pulmonary artery fistula with impaired left ventricular wall motion. Two detachable balloons were deployed in the fistula with complete abolition of flow in the main fistula channel. A small parallel channel of the fistula, previously not appreciated due to vessel overlap, remained patent but had trivial flow as assessed by green-dye and oximetric techniques. The patient had immediate resolution of her symptoms and return of normal ventricular wall motion.

Efficacy of thrombolysis in infrainguinal bypass grafts

The initial outcome of a consecutive series of 43 intra-arterial urokinase infusions for thrombosed infrainguinal grafts in 37 patients was analyzed. There was an 88% (38/43) technical success rate (complete clot lysis) and a 74% (32/43) clinical success rate. Complications occurred in 10 patients (23%) and were related to bleeding in four patients (9%). Patient age, graft age, location, material, and the duration of occlusion did not significantly influence the initial outcome, although there was a trend toward a higher bleeding complication rate among grafts less than or equal to 1 month of age at the time of thrombolysis. A second group of 43 infrainguinal grafts successfully recanalized using regional infusions of thrombolytic agents were followed for long-term patency. This group included 32 grafts successfully treated with urokinase and 11 grafts recanalized with streptokinase. By life-table analysis there was a 55.6% 1-year patency, which fell to 42.4% at 4 years. Vein grafts had significantly (p = 0.01) better long-term patency than prosthetic grafts (69.3% versus 28.6% at 30 months). Grafts with flow-limiting lesions identified and corrected by angioplasty or surgery also had significantly (p = 0.01) better long-term patency than those without such lesions (79.0% versus 9.8% at 2 years). Based on the results of our study compared with a survey of long-term results following secondary surgical procedures for thrombosed infrainguinal grafts, thrombolysis can be recommended in several circumstances. Thrombolysis is indicated for thrombosed vein grafts or when thrombus is present in distal runoff vessels. Thrombosed prosthetic grafts should be replaced by autogenous vein grafts whenever possible.(ABSTRACT TRUNCATED AT 250 WORDS)

Extremity osteosarcomas: intraarterial chemotherapy and limb-sparing resection with 2-year follow-up

Twenty-eight consecutive patients with extremity osteosarcoma (24 stage II, four stage III) received their entire preoperative course of chemotherapy intraarterially in order to maximize local drug concentration and tumor shrinkage to facilitate limb-sparing resection. Eighteen tumors were located in the femur, seven in the tibia, two in the humerus, and one in the fibula. Most patients underwent two catheterizations; thus there was a total of 51 procedures. The average duration of each infusion was 10.4 days. There were eight procedure-related complications, but none precluded completion of intraarterial chemotherapy. Limb-sparing surgery was performed on 25 patients. At a mean follow-up of over 2 years, there was one local recurrence. Among limb-salvage patients with stage II disease, 90% (18 of 20) survived and 75% (15 of 20) are disease-free. Compared with patients from previous studies, this technique permits a high percentage of patients with osteosarcoma to undergo limb-sparing resection without compromise of local disease control or survival.

Palmaz vascular stent: initial clinical experience

The safety and efficacy of the Palmaz balloon-expandable vascular stent and its effect on the results of percutaneous transluminal angioplasty (PTA) were assessed in a prospective study. Technical success was achieved in the placement of 34 of 35 stents (97%) in 27 common and external iliac artery lesions in 19 patients (23 limbs) who presented with disabling claudication, rest pain, or gangrene. Stent placement improved the angiographic results achieved by PTA alone in all 19 patients. Seventeen of 23 limbs (74%) had significant (greater than 20%) elevation of the ankle-arm index after combined angioplasty and stent placement, including nine limbs with occlusive outflow lesions. All 10 patients with continuous runoff distal to the stent and one patient with discontinuous runoff had resolution of their symptoms, remaining unchanged at a mean follow-up time of 6 months. There were three complications: One significantly altered the patient's hospital course, but none detracted from the achieved stent result. Stent placement is effective and does not significantly increase the complication rate of conventional iliac PTA. The current delivery system, however, may limit its utility.

Acceleration of thrombolysis with a high-dose transthrombus bolus technique

The rate of complication and the time necessary to achieve thrombolysis remain major disadvantages of regional thrombolytic therapy. By lacing the entire length of arterial or arterial bypass graft occlusions in the lower extremities of 49 patients with one of two different bolus doses of urokinase (mean, 52,000 International U in 35 infusions = low-dose group [28 patients]; mean, 230,000 U in 23 infusions = high-dose group [21 patients]) prior to identical continuous infusions, it was possible to demonstrate a decrease in the time needed to complete thrombolysis from 33.6 hours in the low-dose group to 10.4 hours in the high-dose group (P less than .001). The total urokinase dose necessary for successful thrombolysis was also significantly less in the high-dose group (P less than .001). The major complication rate was 22.9% in the low-dose group and 8.7% in the high-dose group, although the difference was not statistically significant. The use of urokinase and a high-dose transthrombus bolus injection technique significantly accelerates thrombolysis, decreases the total urokinase dose needed, and may lower the major complication rate.

Porcine model for the development of interventional techniques in the gallbladder

A technique that permits repeated access to the porcine gallbladder through a surgically placed 18 French latex catheter is described and experience with this system in 22 swine is discussed. This porcine gallbladder model produces a reliable and reproducible means for studying clinically applicable interventional procedures.