What we still do not know about adrenal vein sampling for primary aldosteronism.

During the last two decades, primary aldosteronism has emerged as the most common cause of secondary hypertension, and advances in the diagnosis and treatment of this condition have improved patient care substantially. A major stumbling block in the evaluation and management of these patients, which ultimately guides treatment and prognosis, is answering the question, "Which adrenal gland(s) produce aldosterone?" Adrenal vein sampling has emerged as the only reliable method to determine the answer to this question; however, the methodology and criteria for lateralization have been determined empirically with little prospective data. The major remaining controversies surrounding adrenal vein sampling include: who should perform and who should undergo the procedure; what criteria should be used to define a successful study and lateralization of aldosterone production; whether cosyntropin should be infused during the procedure and how; and what to do when results are ambiguous? This article reviews some of the advances in the execution of this procedure, the variations in procedure, the data that fuel the controversies, and the issues that need to be resolved in the future.

Inferior vena cava (IVC) filter thrombosis in a renal transplant recipient.

We report a renal transplant patient with a functioning allograft who had an inferior vena cava (IVC) filter placed above the renal allograft vein. The patient occluded the IVC filter and developed extensive distal thrombosis. This included complete occlusion of the renal allograft vein (RAV). However, this complication did not lead to a loss of kidney transplant function. Alternate allograft venous drainage via capsular collaterals and subsequent recanalization of transplant vein were demonstrated.

Understanding the dialysis access steal syndrome. A review of the etiologies, diagnosis, prevention and treatment strategies.

Distal hypoperfusion ischemic syndrome (DHIS), commonly referred to as hand ischemia or 'steal' after dialysis access placement, occurs in 5-10% of cases when the brachial artery is used, or 10 times that of wrist arteriovenous fistulas (AVFs) using the radial artery. It is typically seen in elderly women with diabetes, and may carry severe morbidity including tissue or limb loss if not recognized and treated. Three distinct etiologies include (1) blood flow restriction to the hand from arterial occlusive disease either proximal or distal to the AV access anastomosis, (2) excess blood flow through the AV fistula conduit (true steal), and (3) lack of vascular (arterial) adaptation or collateral flow reserve (ie atherosclerosis) to the increased flow demand from the AV conduit. These three causes of steal may occur alone or in concert. The diagnosis of steal is based on an accurate history and physical examination and confirmed with tests including an arteriogram, duplex Doppler ultrasound (DDU) evaluation with finger pressures and waveform analysis. Treatment of steal includes observation of developing symptoms in mild cases. Balloon angioplasty is the appropriate intervention for an arterial stenosis. At least three distinct surgical corrective procedures exist to counteract the pathophysiology of steal. The ultimate treatment strategy depends on severity of symptoms, the extent of patient co-morbidity, and the local dialysis access technical team support and skills available.

Duplex ultrasound evaluation for dialysis access selection and maintenance: a practical guide.

Detailed case directed history and examination is the mainstay of dialysis access modality selection, ie site and type of access, as well as for maintenance of dialysis access for longevity. As a logical step following history and physical examination, duplex ultrasound evaluation (DUE) is the most cost effective and non-invasive screening tool for evaluation for access placement and for assessment of an established access. Pre-operative vascular mapping allows selection of the optimal dialysis access modality and site. In established accesses, duplex ultrasound testing will diagnose the majority of vascular access complications and direct proper surgical or interventional radiology management. This review outlines a practical decision-making algorithm using DUE for choosing and managing the dialysis access.

A patient centered decision making dialysis access algorithm.

Much controversy surrounds the establishment of proper planning, placement and management (the best practice pattern) of dialysis access. These include the dialysis type and modality selection, timing of access placement and who places the access. The lack of and the difficulty of performing randomized studies with multiple confounding factors, in an extremely heterogeneous and rapidly changing ESRD population demographics, only partly explains the dialysis access conundrum. Add to this the rapidly developing and competing technologies, the wide spectrum of the professional experience, bias and socio-economic forces to make the ESRD problems as multivariate and complex as life itself. This overview describes a dialysis access algorithm approach to the patient needing renal replacement therapy, considering long-term improved patient outcome as the ultimate objective.

Use of ethylene vinyl alcohol copolymer for tubal sterilization by selective catheterization in rabbits.

PURPOSE: To assess the efficacy of ethylene vinyl alcohol copolymer (Uryx) in nonsurgically occluding the fallopian tube and achieving tubal sterilization in the rabbit model. MATERIALS AND METHODS: Ten mature virgin female New England rabbits underwent transvaginal selective bilateral fallopian tube cannulation with use of a coaxial catheter system under general anesthesia. Selective salpingography was performed bilaterally to assess patency of the fallopian tubes. Ethylene vinyl alcohol copolymer was injected unilaterally through a microcatheter to completely fill the middle portion of the tube. Three to seven days after injection, each animal was bred. Conception was determined by ultrasonography (US) 7-19 days after effective breeding. If pregnant, the rabbit was killed. Otherwise, it was permitted to rebreed until pregnancy was achieved. Histologic specimens of the fallopian tubes were prepared and analyzed. RESULTS: Patency of the fallopian tubes was demonstrated bilaterally in all animals by the free spillage of contrast material into the peritoneum. The delivery of ethylene vinyl alcohol copolymer into the fallopian tubes was successful in all animals but one, in which most of the plug almost immediately extruded into the uterus. Pregnancy was detected by US in the untreated fallopian tube in the nine rabbits that were receptive to breeding. No pregnancies were detected in the injected side. Histologic analysis demonstrated variable degrees of occlusion, fibrosis, and inflammation, with the majority of specimens demonstrating mild to moderate inflammation and moderate to marked fibrosis. CONCLUSION: Ethylene vinyl alcohol copolymer can reliably be placed nonsurgically via the transvaginal approach into the fallopian tubes with use of a coaxial catheter system. Ethylene vinyl alcohol copolymer appears to result in less fibrosis than previously investigated agents and demonstrates a 100% early sterilization rate in the rabbit model.

Treatment of type II endoleaks with Onyx.

Endoleaks are defined as persistent perfusion of an abdominal aortic aneurysm (AAA) after endovascular stent-graft deployment. The authors describe their experience treating six endoleaks with the liquid embolic agent Onyx (ethylene-vinyl-alcohol copolymer). Complete endoleak occlusion was achieved in five of six cases. Follow-up imaging has demonstrated decreased aneurysm diameter in all patients 7-29 weeks (mean = 19.2 weeks) after treatment.

Single-lumen subcutaneous ports inserted by interventional radiologists in patients undergoing chemotherapy: incidence of infection and outcome of attempted catheter salvage.

BACKGROUND: Subcutaneous ports are commonly used for vascular access in patients with cancer undergoing chemotherapy. OBJECTIVES: To determine the incidence of catheter-related infection and to assess the efficacy of catheter salvage in subcutaneous ports. METHODS: We retrospectively reviewed 300 subcutaneous single-lumen chest ports inserted by interventional radiologists in 294 patients between December 1, 1995, and November 15, 1997, at the Cleveland Clinic Foundation, Cleveland, Ohio. The number of days that the catheter remained in situ, infection rate, treatment, and outcome of infection were determined. RESULTS: Two hundred ninety-four patients had a total of 79 748 catheter-days. Vascular access for chemotherapy was the indication for 95% of the subcutaneous ports placed. Seventeen catheters (5.7%) developed 20 episodes of noninfectious complications resulting in the removal of 6 ports. Seventeen patients (5.7%) developed catheter-related infections (2.1/10 000 catheter-days) including 10 episodes of catheter-related bacteremia (1.2/10 000 catheter-days). The most common organism isolated was Staphylococcus aureus. A total of 15 of the 17 infected catheters were removed. Salvage was attempted in 6 patients in whom 4 catheters were eventually removed due to recurrent bacteremia (2 patients) and persistent local infection (2 patients). One of the 10 patients with catheter-related bacteremia developed septic arthritis. There were no complications associated with attempted catheter salvage. CONCLUSIONS: Subcutaneous single-lumen ports inserted by interventional radiologists in patients undergoing chemotherapy have low complication rates but infections remain the leading cause of catheter loss. Antibiotic therapy without catheter removal is unlikely to eradicate catheter-related bacteremia.

Delayed onset of ascending paralysis after thoracic aortic stent graft deployment.

Delayed spinal cord ischemia after thoracic aortic aneurysm repair is an infrequent but devastating complication. The use of stent grafts to exclude aortic aneurysms is thought to decrease the incidence of the neurologic deficit because there is no period of significant aortic occlusion. We report a case of paraplegia that progressed to quadriplegia occurring 48 hours after the apparently successful deployment of a thoracic aortic stent graft.

Synthetic dialysis shunts: thrombolysis with the Cragg thrombolytic brush catheter.

PURPOSE: To evaluate the effectiveness of the Cragg thrombolytic brush catheter for declotting of synthetic arteriovenous dialysis shunts. MATERIALS AND METHODS: In this randomized controlled trial, 77 patients with synthetic forearm loop shunts that were thrombosed were randomly assigned to undergo pharmacomechanical thrombolysis with a pulsed spray (n = 34) or a thrombolytic brush catheter (n = 43). The following findings were evaluated: declotting time, urokinase dose, procedure time, complications, and shunt patency at the first dialysis session and at 3 months. All data were collected prospectively in an unblinded manner. RESULTS: The total amount of urokinase used, including secondary interventions, was 243,657 IU with the catheter versus 476,563 IU with the pulsed spray (P = .001). At 15 minutes, clot lysis was successful in 66% of the patients with the catheter versus in 19% with the pulsed spray (P = .001). At 30 minutes, clot lysis was successful in 98% with the catheter versus 47% with the pulsed spray (P = .001). Procedure complication rates and patency at 3 months were similar for the catheter and the pulsed-spray groups. CONCLUSION: Use of the Cragg catheter with urokinase offered faster and more complete clot lysis than did use of the pulsed spray with urokinase. The amount of urokinase used with the catheter was half that used with the pulsed spray. Shunt patency at 3 months was similar for the two treatment methods.

Comparison of the angiojet rheolytic catheter to surgical thrombectomy for the treatment of thrombosed hemodialysis grafts. Peripheral AngioJet Clinical Trial.

PURPOSE: To compare the clinical effectiveness of the AngioJet F105 rheolytic catheter to that of surgical thrombectomy for the treatment of thrombosed hemodialysis grafts. MATERIALS AND METHODS: This was a multicenter, prospective, randomized trial comparing technical success, primary patency, and complication rates. A total of 153 patients were enrolled: 82 patients in the AngioJet group and 71 patients in the surgical thrombectomy group. Patient follow-up was performed 24-48 hours, 1 month, and 6 months after the procedures. RESULTS: Technical success, as defined by the patient's ability to undergo hemodialysis treatment, was 73.2% for the AngioJet group and 78.8% for the surgical thrombectomy group (P = .41). The primary patency rates of the AngioJet group were 32%, 21%, and 15% at 1, 2, and 3 months, respectively. The primary patency rates for the surgical group were 41%, 32%, and 26% at 1, 2, and 3 months, respectively. This difference approached statistical significance (P = .053). The groups had similar complication rates-14.6% in the AngioJet group and 14.1% in the surgery group-although the surgery group had more major complications (11.3%). In the AngioJet group, there was a transient increase in plasma-free hemoglobin, which normalized within 24-48 hours. CONCLUSIONS: The AngioJet F105 catheter provides similar clinical results when compared to surgical thrombectomy for the treatment of thrombosed hemodialysis grafts. The difference in patency rates between these two techniques approached statistical significance. In addition, results of both thrombectomy methods were inferior to those suggested by the Dialysis Outcomes Quality Initiative guidelines.

Efficacy of percutaneous fibrin sheath stripping in restoring patency of tunneled hemodialysis catheters.

OBJECTIVE: Our objective was to determine the effectiveness of percutaneous fibrin sheath stripping as a method of restoring function to failing tunneled hemodialysis catheters. SUBJECTS AND METHODS: A total of 131 percutaneous fibrin sheath stripping procedures were performed on 100 failing tunneled hemodialysis catheters in 91 patients. Only the initial stripping procedure of the first catheter inserted in each patient was included for analysis. Patients were excluded if an additional cause of catheter failure was noted at the time of percutaneous fibrin stripping. Failure of the hemodialysis catheter was defined as inability to sustain an average blood flow rate of 250 ml/min or more in a hemodialysis session. Patients were followed up until the time of catheter failure, catheter removal, or a second stripping. Poststripping primary patency and complication rates were determined. RESULTS: The technical success of the procedure was 95.6%. Median follow-up was 16 weeks (range, 0-128 weeks). The overall median duration of primary patency after the first stripping was 89 days (3 months). No statistically significant difference in primary patency rates was seen between patients who underwent fibrin sheath demonstration by contrast injection and those who did not (p = .71). Female patients were statistically more likely to have catheter failure after catheter stripping than were male patients (p = .02). The route of catheter insertion did not significantly influence poststripping patency rates. No complications were associated with the procedure. CONCLUSION: Percutaneous fibrin sheath stripping is a safe, effective method of restoring patency to failing hemodialysis catheters when the failure is due to fibrin sheath formation and other causes are excluded.

Acute upper extremity deep venous thrombosis: safety and effectiveness of superior vena caval filters.

PURPOSE: To evaluate the safety and effectiveness of percutaneous filter placement in the superior vena cava for prevention of pulmonary embolism (PE) due to acute upper extremity deep venous thrombosis (DVT) in patients with contraindications to or unsuccessful anticoagulation. MATERIALS AND METHODS: Forty-one patients with acute upper extremity DVT and contraindications to or unsuccessful anticoagulation underwent percutaneous placement of a superior vena caval filter for prevention of PE. Four types of filters were used. Follow-up chest radiographs were used to detect filter migration, dislodgment, and fracture. Placements of central venous and Swan-Ganz catheters after filter insertion were recorded. Patients were followed up clinically for evidence of superior vena cava syndrome and PE. Kaplan-Meier survival rates were determined. Follow-up was 1 day to 221 weeks. RESULTS: No complications such as filter migration, dislodgment, or fracture occurred (median follow-up, 12 weeks). No patients developed clinical evidence of PE due to upper extremity thrombosis or superior vena cava syndrome (median follow-up, 15 weeks). Catheters were placed subsequent to filter placement in 23 patients (56%) without complication. CONCLUSION: Percutaneous filter placement in the superior vena cava is a safe and effective method for preventing symptomatic PE due to acute upper extremity DVT in patients in whom therapeutic anticoagulation has failed or is contraindicated.

Rheolytic thrombectomy in the treatment of acute limb-threatening ischemia: immediate results and six-month follow-up of the multicenter AngioJet registry. Possis Peripheral AngioJet Study AngioJet Investigators.

We tested the efficacy of rheolytic thrombectomy in treating 21 patients (mean age 68+/-12 years; 66% male) and 22 vessels (limbs) who presented to the hospital within 2 weeks of the development of limb-threatening ischemia. Fifty-two percent had contraindications to use thrombolytics, and 57% had severe comorbidities. All of the vessels were occluded with thrombus on the initial angiogram. Procedural success was achieved in 20 limbs (91%). Three patients expired in the hospital, and one expired at follow-up due to nonvascular causes. Acute limb salvage was achieved in 18 of 19 limbs (95%) in the 18 survivors, and 6-month limb salvage was achieved in 16 of 18 limbs (89%) in the 17 survivors. Rheolytic thrombectomy is effective in restoring immediate blood flow in acute limb-threatening ischemia, especially in high-risk surgical patients or patients with contraindications to thrombolytic therapy.

Self-expandable metallic airway stent insertion employing flexible bronchoscopy: preliminary results.

We describe 37 patients in whom 52 self-expandable metallic stents were successfully placed using a flexible bronchoscope. Indications for stenting were tracheobronchomalacia (n=13), neoplasia (n=20), and tracheal stenosis (n=4). Airway patency was restored in all patients. Symptoms improved in all but one patient. The median follow-up for all patients and the group of 16 patients alive has been 21 and 69.5 weeks, respectively. Complications have included granulomas and bronchitis. Migration or mucus plugging was not encountered. We conclude that metallic stents can be inserted safely using a flexible bronchoscope. At least in the short term, major complications are uncommon.

Renal artery stent placement for the management of ischemic nephropathy.

PURPOSE: To evaluate the angiographic and clinical results of percutaneously implanted renal artery endoprostheses (stents) for the treatment of patients with ischemic nephropathy. MATERIALS AND METHODS: During a 52-month period, 45 patients with azotemia (serum creatinine > or = 1.5 mg/dL) and atheromatous renal artery stenosis untreatable by, or recurrent after, balloon angioplasty were treated by percutaneous placement of Palmaz stents. Stent implantation was unilateral in 32 cases and bilateral in 11 cases. Clinical results were determined by measurements of serum creatinine and follow-up angiography. Clinical benefit was defined as stabilization or improvement in serum creatinine level. Angiographic patency was defined as less than 50% diameter recurrent arterial stenosis. RESULTS: Stent placement was technically successful in 51 of 54 (94%) renal arteries. Technical failures were stent misdeployment requiring percutaneous stent retrieval (n = 2) and inadvertent placement distal to the desired position (n = 1). Complications included acute stent thrombosis (n = 1) and early initiation of hemodialysis (within 30 days; n = 1). There were two periprocedural deaths. With use of life-table analysis, clinical benefit was seen in 78% of patients at 6 months (n = 36), 72% at 1 year (n = 24), 62% at 2 years (n = 12), and 54% at 3 years (n = 3). In patients with clinical benefit, average creatinine level was reduced from 2.21 mg/dL +/- 0.91 before treatment to 2.05 mg/dL +/- 1.05 after treatment (P = .018). Lower initial serum creatinine level was associated with a better chance of clinical benefit (P = .05). No other variables affected outcome, including patient age, sex, diabetes, implanted stent diameter, unilateral versus bilateral stent placement, or ostial versus nonostial stent positioning. Conventional catheter angiography or spiral computed tomographic (CT) angiography performed in 19 patients (28 stents) at a mean interval of 12.5 months demonstrated primary patency in 75%. Maintained stent patency appeared to correlate with renal functional benefit. CONCLUSIONS: Percutaneous renal artery stent placement for angioplasty failures or restenoses provides clinical benefit in most patients with ischemic nephropathy.

Tissue response to covered Wallstents.

PURPOSE: To evaluate and compare the healing response related to two types of graft-covered Wallstents (WSs) and an uncovered WS in the canine iliac artery. MATERIALS AND METHODS: Eight bare mesh WSs, 10 polyethylene terephthalate interbraided WSs (PET-WSs), and six polytetrafluoroethylene covered WSs (ePTFE-WSs) were placed in the iliac arteries of 12 dogs. Arteriograms were obtained before and after implantation and at explantation. Devices were explanted at 1 month (n = 8), 3 months (n = 6), and 6 months (n = 10) and sent for histologic study. RESULTS: One ePTFE-covered stent-graft was found to be thrombosed at 3 months; the remaining 23 of 24 implants remained patent to the time of explantation. The WS and ePTFE-WS both generated a uniform myointimal cell response without inflammation. The PET-WS induced a fibrous luminal response with substantial foreign body-type inflammatory reaction around the PET fibers. Although neointima associated with the PET-WS appeared thicker than that associated with either the ePTFE-WS or the bare WS, none of the patent implants developed greater than 50% angiographic narrowing. CONCLUSION: The PET-WS induced chronic inflammation, a response not seen with either the WS or ePTFE-WS. This may explain the occurrence of pain and/or fever in human studies of arterial PET endoluminal stent-grafts. Patency for all three implants was excellent in this model.

Treatment of TIPS stenosis with ePTFE graft-covered stents.

Midshunt stenosis and recurrent variceal bleeding occurred in 2 patients after transjugular intrahepatic portosystemic shunts (TIPS). Repeat angioplasty was performed in both cases but recurrent stenosis again led to hemorrhage. Expanded polytetrafluoroethylene (ePTFE) graft-covered stents were expanded in each of the TIPS at the midshunt, reducing the portosystemic gradient for both patients. Variceal bleeding ceased, and follow-up studies showed no evidence of recurrent stenosis in either case.