Gregory J. Dubel

Fibrin sheath stripping versus catheter exchange for the treatment of failed tunneled hemodialysis catheters: randomized clinical trial.

PURPOSE To compare the effectiveness of two treatments for tunneled hemodialysis catheter malfunction: percutaneous fibrin sheath stripping (PFSS) and over-the-wire catheter exchange (EX). MATERIALS AND METHODS Adult patients with poorly functioning tunneled hemodialysis catheters (flow rates < 200 mL/min) were randomly assigned to receive either PFSS or EX. Over the course of 20 months, 30 patients (37 encounters) referred to a single institution met the inclusion criteria and consented to participate. PFSS employed transcatheter snares via femoral vein puncture, whereas EX was performed over a guide wire with use of fluoroscopic guidance. Patients were followed up to determine the duration of continued adequate hemodialysis via manipulated catheters for up to 4 months (primary outcome measure). RESULTS Overall technical success rate was 97%. Mean catheter patency for the PFSS group was 24.5 +/- 29.3 days, and 52.2 +/- 43 days for the EX group (P < .0001). After EX, patency rates at 1, 2, 3, and 4 months were 71%, 33%, 27%, and 27%, compared to 31%, 16%, 7%, and 0% after PFSS (P = .04, logrank test). Exchanged catheters were significantly more likely to be patent for as long as 4 months (23% versus 0%; P < .05, chi2 test). CONCLUSIONS Malfunctioning tunneled hemodialysis catheters treated by means of EX are significantly more likely to remain patent for up to 4 months than are those treated by means of PFSS. According to the results of this trial, PFSS should not be performed as a routine therapy for catheter malfunction.

The role of percutaneous revascularization for renal artery stenosis

Abstract Renal artery stenosis (RAS) is usually caused by atherosclerosis or fibromuscular dysplasia. RAS leads to activation of the renin-angiotensin-aldosterone system and may result in hypertension, ischemic nephropathy, left ventricular hypertrophy and congestive heart failure. Management options include medical therapy and revascularization procedures. Recent studies have shown angiotensin receptor blockers (ARB) and angiotensin converting enzyme inhibitors (ACE-I) to be highly effective in treating the hypertension associated with RAS and in reducing cardiovascular events; however, they do not correct the underlying RAS and loss of renal mass may continue. Renal artery angioplasty was first performed by Gruntzig in 1978. The routine use of stents has increased technical success rates compared with angioplasty, and surgery is now only rarely performed. Although numerous case series claimed benefit in terms of blood pressure control, no adequately powered randomized, controlled, prospective study of renal artery interventions has reported their effect on cardiovascular morbidity or mortality. The CORAL trial, an ongoing study of renal artery stent placement and optimal medical therapy (OMT) funded by the National Institutes of Health, is the first study to attempt to do so. Until the CORAL trial results are in, physicians will continue to be faced with difficult choices when determining the optimal management for RAS patients and deciding which, if any, patients should be offered revascularization.

Distal Embolic Protection for Renal Arterial Interventions

Distal or embolic protection has intuitive appeal for its potential to prevent embolization of materials generated during interventional procedures. Distal protection devices (DPDs) have been most widely used in the coronary and carotid vascular beds, where they have demonstrated the ability to trap embolic materials and, in some cases, to reduce complications. Given the frequency of chronic kidney disease in patients with renal artery stenosis undergoing stent placement, it is reasonable to propose that these devices may play an important role in limiting distal embolization in the renal vasculature. Careful review of the literature reveals that atheroembolization does occur during renal arterial interventions, although it often goes undetected. Early experience with DPDs in the renal arteries in patients with suitable anatomy suggests retrieval of embolic materials in approximately 71% of cases and renal functional improvement/stabilization in 98% of cases. The combination of platelet inhibition and a DPD may provide even greater benefit. Given the critical importance of renal functional preservation, it follows that everything that can be done to prevent atheroembolism should be undertaken including the use of DPDs when anatomically feasible. The data available at this time support a beneficial role for these devices.

Contemporary endovascular embolotherapy for meningioma.

Preoperative endovascular tumor embolization has been used for 40 years. Meningiomas are the most common benign intracranial tumor in which preoperative embolization has been most extensively described in the literature. Advocates of embolization report that it reduces operative blood-loss, and softens the tumor, thus making surgery safer and easier. Opponents suggest that it adds additional risk and cost for patients without controlled studies showing conclusive benefit. The literature suggests a 3 to 6% neurological complication rate related to embolization. The combined external and internal carotid artery blood supply and complex anastomoses of the meninges can make embolization challenging. Positive outcomes require thorough knowledge of the pertinent vascular anatomy, familiarity with the neurovascular equipment and embolics, and meticulous technique. There remains debate on several aspects of embolization, including tumors most appropriate for embolization, embolic agent of choice, ideal size of embolic, and the choice of vessel(s) to embolize. This detailed review of pertinent vascular anatomy, embolization technique, results, and complications should allow practitioners to maximize treatment outcomes in this setting.

Transcatheter Embolization in the Management of Epistaxis

A majority of the population will experience epistaxis at some time in their life. Most cases will be from an anterior source and can be treated with pressure, anterior nasal packing, or cautery. Intractable epistaxis is generally posterior in origin and may require endoscopic cautery, posterior packing, surgical ligation, or embolization. Embolization has been used to treat epistaxis for more than 30 years and success can be achieved in approximately 90% of patients, with major complications occurring in approximately 2%. These excellent results require thorough knowledge of the regional anatomy, familiarity with the equipment and various agents used to achieve this type of embolization, as well as attention to detail and meticulous technique. There remains debate on several aspects of embolization, including the agent of choice, preferred size of the embolic, and the number of vessels to embolize. Advances in endoscopic surgery have evolved to the point that similar success rates for embolization and modern surgical techniques in treating epistaxis may be expected. This detailed review of pertinent vascular anatomy, embolization technique, and surgical alternatives should allow practitioners to formulate treatment algorithms that result in optimal outcomes at their institutions.

Interventional management of arc of buhler aneurysm.

The Arc of Buhler (AOB) represents a persistence of the ventral anastomosis between the superior mesenteric artery (SMA) and the celiac arterial systems. The exact incidence of the AOB is not known, but it is believed to be ≤ 4%. Aneurysms of this rare anomaly are even more uncommon. We report a case of an aneurysm of the AOB with an intact pancreaticoduodenal artery arcade (PDAA) and near occlusive celiac origin stenosis. Stenoses or occlusions of the celiac origin have been reported in association with AOB aneurysms, as well as in patients with PDAA aneurysms. Transcatheter embolization (TCE) was successfully performed, thereby excluding the AOB aneurysm while preserving flow through the PDAA. To our knowledge, this is the first report of successful percutaneous treatment of an AOB aneurysm. The pathophysiology and management AOB and PDAA aneurysms are reviewed. Review of the literature suggests that TCE, when feasible, is at least as effective as conventional surgery in patients with PDAA aneurysms, but with lower morbidity and mortality. Based on this data and our experience, we believe that TCE should be the initial treatment of choice in patients with PDAA or AOB aneurysms.

Basic Neuroangiography: Review of Technique and Perioperative Patient Care

Neuroangiography (NA) is an important part of diagnosis and treatment of patients with neurological disease. Although NA may be performed for diagnostic purposes, in many instances NA is performed with the intent to treat. Indications for NA range from extracranial diseases (vertebrobasilar insufficiency from subclavian steal, extracranial carotid stenosis, cavernous-carotid fistula, neck trauma, epistaxis, tumor invasion of the carotid artery, and tumor embolization) to intracranial diseases (nontraumatic subarachnoid hemorrhage, cerebral aneurysms, cerebral arteriovenous malformations, cerebral vasospasm, acute stroke, tumor embolization, and WADA test). Similar to peripheral angiography, appropriate preprocedural assessment and postprocedural care, along with understanding of anatomy, catheter technique, and disease processes, are vital to successful outcomes. This article will review the basic technique, equipment, and patient management in NA. With appropriate skill and knowledge, interventional radiologists can perform NA with safe and successful results.

Regional infusion-radioembolization.

Selective internal radiation therapy involves the intra-arterial delivery of radioactive beads to the tumor while minimizing dosing to the adjacent organ. Because this technique invariably results in some degree of embolization, it has also been termed radioembolization. More than 8000 patients have been treated worldwide, with a large body of experience with primary hepatocellular carcinoma (HCC) and metastatic colorectal carcinoma (MCRC) and growing experience with other tumors (metastatic neuroendocrine, breast carcinoma, cholangiocarcinoma). Response rates by FDG-PET are 80% to 90%. Complications are uncommon and most often consist of self-limited malaise. More significant complications, including radiation-induced liver disease, ischemic cholecystitis, and gastrointestinal ulceration may be seen in up to 10% of patients. This underscores the critical importance of patient selection and meticulous technique. Median survival times in patients who have HCC and MCRC are significantly improved compared with historic controls. Further study is required to determine the appropriate role of radioembolization in the context of state-of-the-art chemotherapy and other liver-directed therapies.

Acute Lower Gastrointestinal Bleeding: Temporal Factors Associated With Positive Findings on Catheter Angiography After 99mTc-Labeled RBC Scanning

OBJECTIVE The objective of the study was to determine if time to positive (TTP), defined as the time from the start of (99m)Tc-labeled RBC scanning to the appearance of a radionuclide blush (considered to be a positive finding for acute lower gastrointestinal bleeding [LGIB]), and lag time (LT), defined as the time from the appearance of a radionuclide blush to the start of catheter angiography (CA), affected the yield of CA for the detection of acute LGIB. MATERIALS AND METHODS TTP and LT were retrospectively evaluated in 120 patients who had positive findings for acute LGIB on (99m)Tc-labeled RBC scanning and subsequently underwent CA for the diagnosis and localization of gastrointestinal bleeding. Two nuclear medicine fellowship-trained radiologists independently reviewed the (99m)Tc-labeled RBC scans. Two fellowship-trained interventional radiologists independently reviewed the angiograms. All data were analyzed using SAS software. RESULTS When a TTP threshold of ≤ 9 minutes was used, the sensitivity, specificity, positive predictive value, and negative predictive value for a positive CA study were 92%, 35%, 27%, and 94%, respectively. In addition, the odds of detecting bleeding on CA increased 6.1-fold with a TTP of ≤ 9 minutes relative to a TTP of > 9 minutes (p = 0.020). A significant inverse relationship was found between LT and a positive CA study (p = 0.041). CONCLUSION TTP and LT impact the rate of positive CA studies. A TTP threshold of ≤ 9 minutes allows the detection of almost all patients who would benefit from CA for treatment and allows a reduction in unnecessary negative CA studies. The likelihood of positive findings on CA decreases with a delay in the performance of CA.

Carotid Artery Stenting: Review of Technique and Update of Recent Literature

Stroke is the fourth leading cause of death and the number one cause of long-term disability in the United States. Carotid stenosis is an important cause of ischemic strokes, accounting for 20 to 25%. Previous studies have established carotid endarterectomy as standard of care of symptomatic patients with > 50% stenosis and asymptomatic patients with > 60% stenosis; recently, carotid artery stenting has emerged as an alternative treatment for carotid stenosis. Several studies have been published comparing carotid artery stenting with endarterectomy with mixed results. In this article, the authors discuss carotid artery stenting technique, the results from the most recent trials, and future directions.