Evaluation of a Novel Spun Polytetrafluoroethylene Stent Graft in an Ovine External Iliac Artery Model.

PURPOSE: To evaluate the patency, cellular response, and thrombogenicity of a novel vascular stent graft. MATERIALS AND METHODS: Test stent grafts, incorporating luminal spun polytetrafluoroethylene and a nonpermeable fluoropolymer layer, and control stent grafts, constructed of permeable expanded polytetrafluoroethylene, were implanted in the external iliac arteries of 14 adult sheep with a median weight of 73.4 kg ranging from 60.6-86.8 kg for 30 (n = 4), 90 (n = 4), and 180 (n = 6) days. Angiographic patency and percent diameter stenosis (%DS) were assessed at termination. Excised stent grafts were fixed and stained for histopathologic analysis, including neointimal coverage (NC) assessment. RESULTS: Test and control device migration occurred in 1 animal, resulting in test device thrombosis. Both devices were excluded from analysis. Mean %DS in test and control implants was 4.6% and 8.2% (P = .563), 2.0% and 10.9% (P = .363), and 2.1% and 10.3% (P = .009) at 30, 90, and 180 days, respectively. Median NC scores at 30, 90, and 180 days were significantly lower in middle test device sections (P < .05). Proximal and distal test and control sections exhibited similar median NC scores at all time periods (P > .05). When present, test and control devices exhibited no neointimal detachment from the graft surface. Except for the migrated test device, no thrombus was observed. Transgraft cellular migration was absent in test devices but present in control devices with tissue accumulation around the stent struts. CONCLUSIONS: Test and control devices demonstrated excellent patency in an ovine model. Compared to the control, test devices exhibited significantly lower %DS values at 180 days and significantly lower mid-device NC scores at 30, 90, and 180 days.

Long-term follow-up of TIPS created with expanded poly-tetrafluoroethylene covered stents.

BACKGROUND: Transjugular intrahepatic portosystemic shunts (TIPS) created with expanded poly-tetrafluoroethylene-covered stents have largely replaced bare metal stents. Short-term shunt patency is typically assessed with protocol Doppler ultrasound (US), while little information exists with regard to long-term patency. AIM: We investigated the value of Doppler US in assessing TIPS patency as well as long-term clinical outcomes. METHODS: A retrospective analysis of 59 patients with covered stents used for TIPS between January 2001 and December 2011 was performed. RESULTS: Fifty-four patients had early (median 9 days) Doppler US follow-up. Seven of eight patients with an abnormal baseline US required stent revisions. None of the 46 patients with normal baseline Doppler US required revisions within the first 6 months; six of these patients subsequently had a portogram because of symptoms, but all TIPS were patent. Fifty-two patients survived for long-term (>6 months) follow-up, averaging 654 days and three Doppler US exams. Five of six patients with abnormal follow-up Doppler US required revisions, whereas none of the 46 patients with normal follow-up US had revisions. The recurrence of symptoms of portal hypertension and/or hepatic encephalopathy (HE) was low (4/52 patients). No significant predictors of long-term stenosis were identified. Post-TIPS HE was independent of pre-TIPS HE or Child-Pugh score. CONCLUSIONS: Short-term patency and that at approximately 2 years after TIPS placement was 87 and 77 %, respectively. We conclude that Doppler US at least 1 week after TIPS is warranted, but repeated Doppler US follow-up is probably not necessary in the absence of clinical symptoms.

Salvage of angioplasty failures and complications in hemodialysis arteriovenous access using the FLUENCY Plus Stent Graft: technical and 180-day patency results.

PURPOSE: To review technical and 180-day clinical outcomes when stent grafts were used to treat dysfunctional arteriovenous (AV) hemodialysis access circuits. MATERIALS AND METHODS: The FLUENCY Plus Stent Graft (Bard Peripheral Vascular, Tempe, Arizona) was used to salvage percutaneous transluminal angioplasty (PTA) technical failures and complications in AV access circuits over 2 years. There were 106 patients treated with 138 stent grafts. Indications for stent graft use included residual stenosis after PTA (n = 81), extravasation after PTA (n = 22), early recurrent stenosis (n = 14), pseudoaneurysms (n = 4), and "other" (n = 4). Data were retrospectively analyzed for complications and outcomes. RESULTS: Technical success was achieved in all patients, and clinical success was achieved in 104 (98%) of 106 patients. At 180 days, postintervention primary patency (PIPP) was 47%, and postintervention secondary patency (PISP) was 79%. PIPP was 62% for autogenous fistulas (AVFs) and 35% for prosthetic grafts (AVGs) (P = .010). The 180-day PIPP for stent grafts 9-10 mm in diameter was 63% versus 38% for stent grafts 6-8 mm in diameter (P = .012). Implants that did not cross the elbow had a 180-day PIPP of 47% compared with 25% for implants across the elbow (P = .032). Technical complications were periprocedure AVG thromboses (n = 2), intraprocedural stent graft dislodgment (n = 1), venospasm (n = 2), and contrast agent-related hives (n = 1). One patient returned at 2 months with an infected AVG and stent graft in the outflow vein. CONCLUSIONS: The FLUENCY Plus Stent Graft was effective for maintenance of hemodialysis access circuit patency and was comparable or better than historical outcomes for PTA and bare stents. Factors that favored improved patency included larger diameter devices, use in AVFs, and avoiding placement across the elbow joint.

The safety and effectiveness of the retrievable option inferior vena cava filter: a United States prospective multicenter clinical study.

PURPOSE: To evaluate the safety and effectiveness of the retrievable Option inferior vena cava (IVC) filter in patients at risk for pulmonary embolism (PE). MATERIALS AND METHODS: This was a prospective, multicenter, single-arm clinical trial. Subjects (N = 100) underwent implantation of the IVC filter and were followed for 180 days; subjects whose filters were later removed were followed for 30 days thereafter. The primary objective was to determine whether the one-sided lower limit of the 95% CI for the observed clinical success rate was at least 80%. Clinical success was defined as technical success (deployment of the filter such that it was judged suitable for mechanical protection from PE) without subsequent PE, significant filter migration or embolization, symptomatic caval thrombosis, or other complications. RESULTS: Technical success was achieved in 100% of subjects. There were eight cases of recurrent PE, two cases of filter migration (23 mm), and three cases of symptomatic caval occlusion/thrombosis (one in a subject who also experienced filter migration). No filter embolization or fracture occurred. Clinical success was achieved in 88% of subjects; the one-sided lower limit of the 95% CI was 81%. Retrieval was successful at a mean of 67.1 days after implantation (range, 1-175 d) for 36 of 39 subjects (92.3%). All deaths (n = 17) and deep vein thromboses (n = 18) were judged to have resulted from preexisting or intercurrent illnesses or interventions and unrelated to the filter device; all deaths were judged to be unrelated to PE. CONCLUSIONS: Placement and retrieval of the Option IVC filter were performed safely and with high rates of clinical success.

Stent graft versus balloon angioplasty for failing dialysis access grafts: a long-awaited advance in the treatment of permanent hemodialysis access.

Arteriovenous grafts (AVGs) for hemodialysis have a high failure rate, often due to the development of stenosis at the graft-to-vein anastomosis. Angioplasty (PTA) has been used for over two decades to treat AVG stenosis, with good technical success but limited AVG patency. Results of a prospective multi-center randomized trial, comparing stent graft to PTA in AVGs, has demonstrated superior access circuit patency for the stent graft group. Recent publication of this clinical study brings us into an exciting new era of dialysis access management using covered stents to improve durability of catheter-based therapy.

Imaging evaluation of lower extremity infrainguinal disease: role of the noninvasive vascular laboratory, computed tomography angiography, and magnetic resonance angiography.

Peripheral arterial disease (PAD) is a manifestation of systemic atherosclerosis that commonly affects the lower extremities. The diagnosis of PAD and the subsequent treatment decisions rely on clinical exam and non-invasive imaging. The imaging modalities that aid in both diagnosis and treatment are the non-invasive vascular laboratory, computed tomography angiography (CTA) and magnetic resonance angiography (MRA). Each modality has its own advantages and limitations. Non-invasive vascular laboratory testing can be used as a good screening tool for PAD and is often used in conjunction with an additional imaging modality if necessary. CTA and MRA have similar advantages when compared to the "gold standard" of digital subtraction angiography. CTA utilizes ionizing radiation, however is readily available and cheaper when compared to MRA. CTA is attractive due to its 3-D reconstruction and multiplanar ability, but CTA can be limited in the presence of calcification. MRA also is attractive for its 3-D multiplanar imaging. It is important for a clinician to be familiar with the principles and technical aspects of each modality as it relates to lower extremity infrainguinal disease.

Expanded polytetrafluoroethylene-covered stent treatment of angioplasty-related extravasation during hemodialysis access intervention: technical and 180-day patency.

PURPOSE: To review technical and patency results with expanded polytetrafluoroethylene (ePTFE)-covered stents for treatment of venous rupture encountered during percutaneous hemodialysis intervention. MATERIALS AND METHODS: The Fluency covered stent is a tracheobronchial device that was used in an off-label manner to treat percutaneous transluminal angioplasty (PTA)-induced rupture in hemodialysis circuits. Data were retrospectively reviewed for all patients treated with the stent in 2004-2005 at two medical centers for PTA-related rupture. RESULTS: From a database of 106 procedures, 21 patients (21 procedures) were treated with the ePTFE-covered stent for PTA-related extravasation. Nine patients had arteriovenous (AV) grafts and 12 had AV fistulas. Five extravasations followed angioplasty as part of an AV graft declotting procedure. Location of extravasation was the outflow or cannulation venous segment (n = 11), cephalic arch (n = 3), AV graft venous anastomosis (n = 6), and intragraft (n = 1). All procedures were technically successful at halting extravasation and preserving vascular access. There were no known complications, and all patients underwent a successful first dialysis session. Twenty of the 21 circuits remained patent beyond the first week after intervention. The 180-day primary circuit patency rate was 20% and the 180-day cumulative circuit patency rate was 65%. CONCLUSIONS: In 21 patients, the ePTFE-covered stent successfully treated PTA-induced rupture with no need for acute secondary procedures such as thrombolysis or surgery. There was no instance of pseudoaneurysm formation or delayed bleeding. The ePTFE-covered stent offers advantages compared to prolonged PTA or bare stents when attempting to preserve hemodialysis access after PTA-induced rupture.

Rapid cortisol assays improve the success rate of adrenal vein sampling for primary aldosteronism.

OBJECTIVE: We hypothesized that an adrenal vein sampling (AVS) algorithm incorporating rapid cortisol assays, which enables resampling of the adrenal veins, would improve the success rate by a team of radiologists. SUMMARY BACKGROUND DATA: AVS is the most accurate means to localize aldosterone production in primary aldosteronism (PA). However, cannulation of the right adrenal vein (RAV) is difficult, and success is assumed from venography without the support of steroid assays. Furthermore, few institutions can assign all studies to 1 dedicated and experienced AVS interventional radiologist. METHODS: Retrospective chart review of patients with PA at our university hospitals who underwent AVS. We compared results for 30 AVS studies incorporating rapid cortisol assays with 30 conventional AVS studies. RESULTS: The success rate for the control period was 73% (22/30 studies). For the first 30 studies after incorporating rapid cortisol assay, the success rate increased to 97% (29/30 studies). Resampling the RAV was required for 2 studies, and prolonged sheath insertion did not cause any complications. CONCLUSIONS: High AVS success rates may be achieved by a team of interventional radiologists at 1 center using defined AVS protocols. Rapid cortisol assay allows for resampling of the RAV and improves AVS success rates.

Covered stents for late postoperative arterial hemorrhage after pancreaticoduodenectomy.

The use of covered stents in treating delayed postoperative hepatic artery hemorrhage after pancreaticoduodenectomy may preserve hepatic arterial flow. The authors report two cases of massive hemorrhage after pancreaticoduodenectomy that were successfully treated with covered stents. Computed tomographic angiography demonstrated postprocedure patency of the hepatic arteries at 13 and 15 months, respectively. When technically feasible, percutaneous placement of stent-grafts may be used as a first-line intervention in delayed hemorrhage after pancreaticoduodenectomy.

Sealing of type III endoleaks with ethylene vinyl alcohol copolymer in a canine model.

PURPOSE: To test ethylene vinyl alcohol copolymer (EVOH) as a sealing agent for persistent abdominal aortic aneurysm (AAA) endograft leaks. MATERIALS AND METHODS: Twelve dogs underwent creation of AAAs with a Palmaz P4014 stent. A 10-mm x 5-cm Wallgraft endoprosthesis with a 4-mm-diameter hole cut into its side was deployed within the AAA. One week later, computed tomography (CT) and angiography were performed and the aneurysm sac was catheterized through the 4-mm hole. Then, EVOH was injected into the sac and lumbar arteries. Four weeks thereafter, all surviving animals underwent repeat CT scanning and angiography and were then euthanized. The AAA underwent gross and microscopic study. RESULTS: Three dogs died from aortic rupture within 24 hours of AAA creation and the remaining nine dogs survived to receive EVOH. All nine dogs had persistent flow into the sac and lumbar arteries at the time of EVOH delivery. Seven dogs survived to the end of the experiment, and all aneurysm sacs and lumbar arteries remained occluded on angiography and CT. Histologic examination revealed EVOH and thrombus admixed, with thrombus in varying stages of organization filling the aneurysm sac and lumbar arteries. CONCLUSIONS: Embolization of type III endoleaks with EVOH proved to be feasible in a canine model. Further work is warranted to determine its therapeutic utility.

Measurement of 18-hydroxycorticosterone during adrenal vein sampling for primary aldosteronism.

CONTEXT: In primary aldosteronism, elevated serum 18-hydroxycorticosterone (18OHB) suggests aldosterone-producing adenoma (APA) rather than bilateral, idiopathic hyperaldosteronism (IHA), but little is known about the relative production of 18OHB and aldosterone (A) in APAs compared with IHA. OBJECTIVES: We measured 18OHB, A, and cortisol (F) in blood from adrenal vein sampling (AVS) studies. We compared the discriminatory power of gradients in 18OHB/A and 18OHB/F ratios with A/F ratio gradients for distinguishing APA from IHA. DESIGN, SETTING, AND SUBJECTS: We measured 18OHB and A in excess serum from 23 AVS studies performed at our university hospitals. MAIN OUTCOME MEASURES: We calculated the ratios 18OHB/A, 18OHB/F, and A/F for all specimens, and determined the adrenal vein gradients for these ratios. RESULTS: The 18OHB/A ratios were much lower in blood draining APAs (2.17 +/- 0.62) than in blood draining the contralateral adrenals (12.96 +/- 12.76; P < 0.001) but similar to blood draining IHA adrenals (4.69 +/- 4.32; P = 0.02). In contrast, the 18OHB/F ratios were elevated in specimens from APAs (26.03 +/- 11.51) compared with IHA adrenals (9.22 +/- 5.18; P < 0.001) or the contralateral adrenals (6.23 +/- 2.97; P < 0.001). Using 18OHB/F gradient greater than two or 18OHB/A gradient less than 0.5 as criteria for lateralization, interpretations agreed with lateralizations based on A/F gradients in 21 of 23 cases. CONCLUSIONS: High serum 18OHB in APA reflects augmented production of both 18OHB and A, not disproportionate 18OHB secretion relative to A. The 18OHB/A and 18OHB/F gradients are useful adjuncts but not as reliable as A/F gradients for A lateralization during AVS.

Contemporary techniques and safety of cardiovascular procedures in the surgical management of renal cell carcinoma with tumor thrombus.

OBJECTIVE: Renal cell carcinomas often form venous thrombi that extend into the vena cava. Frequently, cardiovascular consultation is necessary for complete surgical excision. We sought to investigate the risk factors, surgical techniques, and outcomes of patients treated for renal cell carcinoma with venous extension. METHODS: We reviewed the records of 46 consecutive patients who underwent surgical management of renal cell carcinoma with venous extension between 1991 and 2005. Data on patient history, staging, surgical techniques, morbidity, and survival were analyzed. RESULTS: There were 29 men and 17 women with a mean age of 60.2 +/- 12.0 years. Twenty-five (54%) procedures were completed with cardiovascular assistance. Nephrectomy was performed in 44 (96%) cases. Three (7%) patients underwent right heart venovenous bypass, and 2 (5%) patients underwent cardiopulmonary bypass with circulatory arrest. Fourteen (32%) patients had perioperative complications, including 1 (2%) perioperative death. Patients who required cardiovascular procedures (inferior vena cava clamping, right heart venovenous bypass, and cardiopulmonary bypass with circulatory arrest) had higher risks of perioperative complications (P < .02). The 1-, 2-, and 5-year overall survival rates were 78%, 69%, and 56%. CONCLUSIONS: This large series demonstrates that aggressive treatment of renal cell carcinoma with venous thrombus provides favorable outcomes. Our 5-year survival is among the highest of recent reviews, and our perioperative morbidity and mortality rates are comparable with those of other series. Tumors that require cardiovascular procedures are associated with increased complications when compared with radical nephrectomy and thrombectomy alone. Nevertheless, this aggressive treatment approach offers encouraging patient survival.

CT angiography of lower extremity vascular bypass grafts.

Over the past several years computed tomography (CT) technology has advanced to such a degree that CT angiography (CTA) has become the study of choice at our institution for imaging lower extremity vascular bypass grafts. CTA quickly provides anatomic information about the state of the graft and identifies virtually all forms of bypass graft failure and related complications. Furthermore, detailed vascular anatomy is seen beyond the graft and affords sufficient anatomic detail for surgical revision without the need for other angiographic studies. Although catheter angiography, duplex-ultrasound, magnetic resonance angiography, and nuclear medicine studies all continue to play some role in the evaluation of vascular grafts, they are more often used as problem solving modalities when CTA findings are equivocal. Whereas it was once essential to catheterize directly through a failing bypass graft or pass catheters into the graft from a distant arterial puncture to obtain an angiogram of a failing bypass graft, CTA produces arteriograms with only intravenous contrast administration, a brief visit to the CT scanner, and return to daily activities without catheterization, discomfort, or risk to the bypass conduit.

Percutaneous radiofrequency ablation of renal tumors: technique, limitations, and morbidity.

OBJECTIVES: To evaluate our evolving experience with percutaneous radiofrequency (RF) renal tumor ablation and focus on our technique to ensure maximal treatment efficacy and reduce the possibility of complications. METHODS: Fifteen patients with small (less than 4 cm) posterior or lateral contrast-enhancing (more than 10 Hounsfield units) renal tumors were candidates for RF treatment. Of these patients, 12 (13 tumors) received computed tomography-guided percutaneous RF ablation. General anesthesia was administered in all but our first 2 patients, who received intravenous sedation. After treatment, patients were closely followed up with computed tomography scans at 6 weeks and 3, 6, and 12 months, and every 6 months thereafter. Successful ablation was defined as a lesion along with a margin of normal parenchyma that no longer enhanced (less than 10 Hounsfield units) on follow-up contrast imaging. RESULTS: The mean tumor size was 2.4 +/- 0.6 cm. The average procedure time was 95 minutes (range 60 to 150) and length of stay 0.9 days. All patients underwent the procedure without any major complications. At a mean follow-up of 4.9 months, 12 (93%) of 13 tumors were successfully ablated. In 3 patients, the procedure was not performed because of intervening bowel or lung parenchyma when positioned in the prone position before the procedure. Computed tomography-guided percutaneous RF ablation of small renal tumors is a viable minimally invasive treatment option with a high short-term success rate and low morbidity. This new technology must be uniformly applied to assess its long-term efficacy.