Treatment of Aortoiliac Occlusive Disease with the Endologix AFX Unibody Endograft.

OBJECTIVE/BACKGROUND: Aorto-bifemoral bypass remains the gold standard for treatment of aortoiliac occlusive disease (AIOD) in patients with advanced (TASC D) lesions, but has significant associated morbidity and mortality. Treatment with a unibody stent-graft positioned at the aortic bifurcation is a potential endovascular option for the treatment of AIOD. The current study examines the safety, efficacy, and early patency rates of the Endologix AFX unibody stent-graft for treatment of AIOD. METHODS: A multicenter retrospective review was conducted of patients treated exclusively for AIOD with the AFX device. Primary, assisted primary, and secondary patency rates were noted. Clinical improvement was assessed using Rutherford classification and ankle brachial index. Mean duration of follow-up was 22.2 ± 11.2 months. Ninety-one patients (56 males [62%]) were studied. RESULTS: Sixty-seven patients (74%) presented with lifestyle-limiting intermittent claudication and the remaining 24 (26%) had critical limb ischemia. Technical success was 100%. Complications included groin infection (n = 4 [4%]), groin hematoma (n = 4 [4%]), common iliac rupture (n = 4 [4%]), iliac dissection (n = 4 [4%]), and thromboembolic event (n = 3 [3%]; one femoral, one internal iliac artery, and one internal iliac with bilateral popliteal/tibial thromboemboli). Thirty-day mortality was 1% (1/91) resulting from a case of extensive pelvic thromboembolism. At 1 year, 73% of patients experienced improvement in Rutherford stage of -3 or greater compared with baseline. Nine patients (10%) required 16 secondary interventions. At all time points, primary patency rates were > 90%, assisted patency rates were > 98%, and secondary patency rates were 100%. CONCLUSION: This is the largest study to examine the use of the Endologix AFX unibody stent-graft for the treatment of AIOD. Use of the AFX stent-graft appears to be a safe and effective endovascular treatment for complex AIOD.

Exploiting parallel R in the cloud with SPRINT.

BACKGROUND: Advances in DNA Microarray devices and next-generation massively parallel DNA sequencing platforms have led to an exponential growth in data availability but the arising opportunities require adequate computing resources. High Performance Computing (HPC) in the Cloud offers an affordable way of meeting this need. OBJECTIVES: Bioconductor, a popular tool for high-throughput genomic data analysis, is distributed as add-on modules for the R statistical programming language but R has no native capabilities for exploiting multi-processor architectures. SPRINT is an R package that enables easy access to HPC for genomics researchers. This paper investigates: setting up and running SPRINT-enabled genomic analyses on Amazon's Elastic Compute Cloud (EC2), the advantages of submitting applications to EC2 from different parts of the world and, if resource underutilization can improve application performance. METHODS: The SPRINT parallel implementations of correlation, permutation testing, partitioning around medoids and the multi-purpose papply have been benchmarked on data sets of various size on Amazon EC2. Jobs have been submitted from both the UK and Thailand to investigate monetary differences. RESULTS: It is possible to obtain good, scalable performance but the level of improvement is dependent upon the nature of the algorithm. Resource underutilization can further improve the time to result. End-user's location impacts on costs due to factors such as local taxation. CONCLUSIONS: Although not designed to satisfy HPC requirements, Amazon EC2 and cloud computing in general provides an interesting alternative and provides new possibilities for smaller organisations with limited funds.

PDQ Wizard: automated prioritization and characterization of gene and protein lists using biomedical literature.

SUMMARY: PDQ Wizard automates the process of interrogating biomedical references using large lists of genes, proteins or free text. Using the principle of linkage through co-citation biologists can mine PubMed with these proteins or genes to identify relationships within a biological field of interest. In addition, PDQ Wizard provides novel features to define more specific relationships, highlight key publications describing those activities and relationships, and enhance protein queries. PDQ Wizard also outputs a metric that can be used for prioritization of genes and proteins for further research. AVAILABILITY: PDQ Wizard is freely available from http://www.gti.ed.ac.uk/pdqwizard/.

Catheter-directed thrombolysis for lower extremity deep vein thrombosis.

The elimination of the embolic potential of existing thrombus, the restoration of unobstructed flow, the prevention of further thrombosis, and the preservation of venous valve function are the ideal goals of therapy for acute deep vein thrombosis (DVT). Meeting these goals will not only prevent pulmonary embolism but will also minimize the long-term sequelae of venous hypertension and the development of postthrombotic syndrome (PTS). Treatment strategies aimed at eliminating or reducing the risk of PTS should focus on preserving valvular function and eliminating the risk of continued venous obstruction after acute DVT. Thrombolytic agents are an attractive form of early therapy because they have the ability to eliminate obstructive thrombus in the deep veins and should therefore help provide protection against PTS. The perceived benefits of early and rapid recanalization in preserving valve function has been the basis for the use of lytic therapy to treat acute DVT.

Reteplase in the treatment of peripheral arterial and venous occlusions: a pilot study.

PURPOSE: Reteplase, a truncated mutant of tissue plasminogen activator, has been used successfully in the treatment of acute coronary occlusion, but, heretofore, it has not been investigated in the setting of peripheral vascular occlusion. Reteplase is a potential recombinant thrombolytic agent that may offer an appropriate alternative to currently employed plasminogen activators. MATERIALS AND METHODS: Over a 6-month period reteplase was used to treat peripheral vascular occlusions at five centers in the United States. The agent was used in peripheral arterial occlusion (n = 26, 70.3%) or venous occlusion (n = 11, 29.7%), in doses ranging from 0.5 to 2.0 U/h, infused directly into the thrombus. A lacing dose (4.3 +/- 0.9 U) was employed in 17 patients (45.9%), and 25 patients (67.6%) received concurrent heparin therapy in a subtherapeutic dose (n = 14, 37.8%) or as full therapeutic anticoagulation (n = 11, 29.7%). RESULTS: The 26 patients with arterial occlusions received a total dose of reteplase that averaged 20.5 U +/- 5.3 (mean +/- SEM), ranging from 3.5 to 82 U. The duration of infusion was 19.3 hours +/- 2.4 with a range of 0.2-36 hours. Complete dissolution of the occluding thrombus was achieved in 23 patients (88.5%). Hemorrhagic complications developed in eight patients (30.8%) and were major in five patients (19.2%). No patient experienced intracranial bleeding. Although there was no association between the dose regimen and thrombolytic efficacy, bleeding complications appeared to be more frequent as the dose was increased from 0.5 to 2.0 U/h. The 11 patients treated for deep venous thrombi received an average of 32.6 U +/- 7.4 of reteplase, ranging from 6 to 75 U over a mean length of time of 31.1 hours +/- 7.3 (range, 4-84 hours). Complete dissolution of thrombus occurred in eight patients (72.7%). Hemorrhagic complications developed in three patients (27.3%) and one of the episodes was major (9.1%). No patient experienced intracranial hemorrhage. CONCLUSIONS: Reteplase appears to be an acceptable alternative thrombolytic agent with a satisfactory safety and efficacy profile in the setting of peripheral arterial and venous occlusion. As such, it may provide an attractive alternative for the treatment of peripheral arterial and venous thrombotic occlusions. However, definitive conclusions must await the results of controlled comparisons of reteplase to other thrombolytic agents.

Catheter-directed thrombolysis for iliofemoral deep venous thrombosis improves health-related quality of life.

PURPOSE: Treatment designed to eliminate thrombus in patients with iliofemoral deep venous thrombosis (DVT) is theoretically attractive; however, its benefits, compared with those of anticoagulation, have not been definitively demonstrated. Although not previously analyzed, an effective measure of treatment success is likely to be the assessment of health-related quality of life (HRQOL). This study evaluated whether catheter-directed thrombolysis for iliofemoral DVT is associated with improved HRQOL, compared with standard anticoagulation, and whether HRQOL outcome in the thrombolysis group is related to lytic success. METHODS: An 80-item self-administered HRQOL questionnaire was developed. It contained the Health Utilities Index, Short Form-12, and disease-targeted scales, including health distress, stigma, health interference, physical functioning, and symptoms (eg, leg swelling, pain, ulcers). The HRQOL questionnaire was confirmed to be reliable and valid by means of psychometric testing. Questionnaires were administered to 98 retrospectively identified patients who had had iliofemoral DVT treated at least 6 months earlier. Sixty-eight patients who were identified through a DVT registry were treated with catheter-directed thrombolysis with urokinase (UK), and 30 patients who were identified by means of a medical record review were treated with anticoagulation alone. The treatment decision was made by the attending physician, and all patients were candidates for both thrombolysis and anticoagulation. RESULTS: Most patients were women (61%), white (95%), married (65%), and had a mean interval since initial DVT of 16 months. The group treated with UK was younger (53 +/- 17 years) than the group treated with heparin (61 +/- 6 years; P =.039). After treatment, patients treated with UK reported better overall physical functioning (P =.046), less stigma (P =.033), less health distress (P =.022), and fewer post-thrombotic symptoms (P =. 006), compared with the patients treated with anticoagulation alone. Within the UK group, phlebographically successful lysis correlated with improved HRQOL (P =.038). Patients classified as lytic failures had similar outcomes to patients treated with heparin. CONCLUSION: Patients with iliofemoral DVT treated with catheter-directed thrombolysis have better functioning and well-being, compared with patients treated with anticoagulation alone. Successful lysis was directly correlated with improved HRQOL, with patients who were classified as lytic failures having similar outcomes to patients treated with heparin. These data support the need for a future randomized trial, which should include an HRQOL measure as part of the outcome analysis.

Endovascular therapy of iliac arteries: routine application of intraluminal stents does not improve clinical patency.

Our objective in this study was to review our experience with endovascular therapy of iliac artery occlusive disease over the past decade, and to compare the results of angioplasty alone with the addition of endovascular stents to these procedures. This report details a retrospective analysis of clinical data on 141 consecutive patients with iliac artery occlusive disease, treated by balloon angioplasty alone, or with the addition of intraluminal stents. The procedures analyzed included 58 common iliac artery interventions (26 angioplasties and 32 stent insertions) and 83 external iliac artery procedures (43 angioplasties and 40 stent insertions). Early and continued success, and their components, are reported and compared according to published standards. While endovascular therapy of iliac artery occlusive disease is effective in relieving symptoms, clinical patency rates are lower than those reported for direct reconstruction. Primary stent placement has not enhanced clinical patency in the iliac arteries, and the selective insertion of these devices for more complicated angioplasty procedures seems warranted.

Catheter-directed thrombolysis for lower extremity deep venous thrombosis: report of a national multicenter registry.

PURPOSE: To evaluate catheter-directed thrombolysis for treatment of symptomatic lower extremity deep venous thrombosis (DVT). MATERIALS AND METHODS: From a registry of patients (n = 473) with symptomatic lower limb DVT, results of 312 urokinase infusions in 303 limbs of 287 patients (137 male and 150 female patients; mean age, 47.5 years) were analyzed. DVT symptoms were acute (< or = 10 days) in 188 (66%) patients, chronic (> 10 days) in 45 (16%), and acute and chronic in 54 (19%). A history of DVT existed in 90 (31%). Lysis grades were calculated by using venographic results. RESULTS: Iliofemoral DVT (n = 221 [71%]) and femoral-popliteal DVT (n = 79 [25%]) were treated with urokinase infusions (mean, 7.8 million i.u.) for a mean of 53.4 hours. After thrombolysis, 99 iliac and five femoral vein lesions were treated with stents. Grade III (complete) lysis was achieved in 96 (31%) infusions; grade II (50%-99% lysis), in 162 (52%); and grade I (< 50% lysis), in 54 (17%). For acute thrombosis, grade III lysis occurred in 34% of cases of acute and in 19% of cases of chronic DVT (P < .01). Major bleeding complications occurred in 54 (11%) patients, most often at the puncture site. Six patients (1%) developed pulmonary emboli. Two deaths (< 1%) were attributed to pulmonary embolism and intracranial hemorrhage. At 1 year, the primary patency rate was 60%. Lysis grade was predictive of 1-year patency rate (grade III, 79%; grade II, 58%; grade I, 32%; P < .001). CONCLUSION: Catheter-directed thrombolysis is safe and effective. These data can guide patient selection for this therapeutic technique.

Impact of peripherally inserted central catheters on phlebitic complications of peripheral intravenous therapy in spinal cord injury patients.

We investigated the impact of peripherally inserted central catheter (PICC) placement in spinal cord injury patients at high risk for infusion phlebitis. The rate and etiology of phlebitis was investigated in two phases. During Phase I, peripheral IV cannulae and conventional central venous catheters (CVC) were used. During Phase II, patients identified to be at risk for phlebitis received PICCs. The number of peripheral IVs, CVCs and PICCs was tabulated for both phases of the study. Technical, infectious and thrombotic complications were studied prospectively for PICCs and retrospectively for CVCs. We found the rate of phlebitis was 16.5 percent and 2.4 percent for Phases I and II, respectively (p = 0.0002). Three infections occurred in 38 PICCs and one infection was documented in 13 conventional CVCs. The number of peripheral IVs and conventional CVCs was reduced significantly from Phase I to Phase II. No procedural complications, catheter sepsis or clinically apparent venous thrombosis occurred. In conclusion, PICCs reduced the rate of phlebitis thresholds with a low complication rate and reduced the use of peripheral IVs and conventional CVCs.

Pulmonary artery thrombolysis and stenting after a bilateral sequential lung transplantation.

Bilateral sequential lung transplantation was complicated by pulmonary artery anastomotic stenosis and bilateral pulmonary thromboemboli. Pulmonary artery thrombus was eliminated by intrathrombotic but not by systemic administration of urokinase. The pulmonary emboli resulted in localized pulmonary infarctions, supporting the need for thrombolytic intervention to restore pulmonary perfusion in the absence of collateral bronchial blood flow after lung transplantation. Pulmonary artery stenosis was relieved by endovascular stenting, avoiding an early reoperative procedure. This case suggests that direct administration of thrombolytic agent may be superior to intravenous administration in the treatment of pulmonary thromboemboli. Pulmonary arterial anastomotic stenoses after lung transplantation can be relieved by endovascular procedures.

Detection of glutamate/glutamine resonances by 1H magnetic resonance spectroscopy at 0.5 tesla.

Midfield proton magnetic resonance spectroscopy (MRS) provides a noninvasive method to monitor glutamate and glutamine (Glx) levels in vivo. Experiments to detect the gamma and beta resonances of Glx have been performed by using commercial 0.5 T and 1.5 T MR scanners on seven patients with elevated blood ammonia and eight normal volunteers. Compared with the spectral sensitivity obtained on an otherwise identical system operating at 1.5 T, the singlet resonance of N-acetyl aspartate (NAA) was decreased by a factor of 1.48, which is significantly less than expected using the ratio of Boltzman populations at the two field strengths. However, the resonances of Glx at 0.5 T increased in signal-to-noise ratio (SNR) by a factor of 2. The increased SNR of Glx is principally due to improved B0 main-field homogeneity and collapse of the strongly J-coupled Glx resonances. Our preliminary results suggest that midfield proton MRS will provide significant clinical utility in the detection of Glx levels in human brain.

Interventional procedures in the intensive care unit patient.

Image-guided interventional techniques have markedly altered the management of many cardiothoracic problems in the intensive care unit. These techniques are less invasive, more patient friendly, and cost-effective. This article covers venous line placement and management, transpleural and transpulmonary biopsy and drainage procedures and interventions for variceal bleeding, massive hemoptysis, massive pulmonary embolism, and veno-occlusive disease.

Fibrin sleeve stripping for salvage of failing hemodialysis catheters: technique and initial results.

PURPOSE: To evaluate percutaneous fibrin sleeve stripping (PFSS) to prolong functional patency in failing hemodialysis catheters. MATERIALS AND METHODS: Forty PFSS procedures were performed in 24 catheters in 23 consecutive patients with an inadequate blood flow rate (< 200 mL/min) during hemodialysis. The fibrin sleeve was mechanically stripped off the shaft of the catheter with a snare introduced via the common femoral vein. Durability of PFSS was determined with life-table analysis. RESULTS: Median time from catheter placement to initial failure was 3.5 months (range, 5 days to 22 months). The technical success rate for PFSS was 100%; initial patency was restored in 39 of 40 procedures (98%), and no symptomatic pulmonary embolism occurred. Primary patency after single PFSS was 45% at 3 months and 28% at 6 months (median added patency, 2.8 months). Postprocedure secondary patency with multiple PFSS procedures was 83% at 3 months and 72% at 6 months (P = .01) (overall catheter patency, 90% at 6 months and 81% at 1 year [P < .001]). CONCLUSION: Multiple PFSS procedures can prolong patency in hemodialysis catheters with a fibrin sleeve.

Detection of pulmonary embolism in patients with unresolved clinical and scintigraphic diagnosis: helical CT versus angiography.

OBJECTIVE: This study was designed to prospectively compare helical CT with pulmonary angiography in the detection of pulmonary embolism in patients with an unresolved clinical and scintigraphic diagnosis. SUBJECTS AND METHODS: Twenty patients with an unresolved suspicion of pulmonary embolism were evaluated with contrast-enhanced helical CT and with selective pulmonary angiography. An average of 11 hr separated the two studies. The CT scans were obtained during one 24-sec or two 12-sec breath-holds. CT scans were interpreted without knowledge of the results of scintigraphy or angiography. Selective pulmonary angiograms were obtained with knowledge of the findings on the ventilation/perfusion scan only. The sensitivity and specificity of CT were compared with those of angiography for central vessels (segmental and larger) only and for all vessels. RESULTS: Eleven of the 20 patients had proved pulmonary embolism (seven in central vessels and four in subsegmental vessels only). When only central vessels were analyzed, CT sensitivity was 86%, specificity was 92%, and the likelihood ratio was 10.7. However, when subsegmental vessels were included, CT results were 63%, 89%, and 5.7, respectively. CONCLUSION: In our subset of patients, helical CT was only 63% sensitive. Subsegmental emboli are difficult to diagnose. Pulmonary angiography remains the study of choice. CT has a limited role in the evaluation of acute pulmonary embolism.