Infolding and collapse of thoracic endoprostheses: manifestations and treatment options.

OBJECTIVES: We sought to review the clinical sequelae and imaging manifestations of thoracic aortic endograft collapses and infoldings and to evaluate minimally invasive methods of repairing such collapses. METHODS: Two hundred twenty-one Gore endografts (Excluder, TAG; W. L. Gore & Associates, Inc, Flagstaff, Ariz) were deployed in 145 patients for treatment of pathologies including aneurysms and pseudoaneurysms, dissections, penetrating ulcers, transections, fistulae, mycotic aneurysms, and neoplastic invasions in 6 different prospective trials at a single institution from 1997 to 2007. Device collapses and infoldings were analyzed retrospectively, including review of anatomic parameters, pathologies treated, device sizing and selection, clinical sequelae, methods of repair, and outcome. RESULTS: Six device collapses and infoldings were identified. Oversized devices placed into small-diameter aortas and imperfect proximal apposition to the lesser curvature were seen in all proximal collapses, affecting patients with transections and pseudoaneurysms. Infoldings in patients undergoing dissection represented incomplete initial expansion rather than delayed collapse. Delayed collapse occurred as many as 6 years after initial successful deployment, apparently as a result of changes in the aortic configuration from aneurysmal shrinkage. Clinical manifestations ranged from life-threatening ischemia to complete lack of symptoms. Collapses requiring therapy were remedied percutaneously by bare stenting or in one case by branch vessel embolization. CONCLUSIONS: Use of oversized devices in small aortas carries a risk of device failure by collapse, which can occur immediately or after years of delay. When clinically indicated, percutaneous repair can be effectively performed.

Bidirectionally adjustable TIPS reduction by parallel stent and stent-graft deployment.

Excessive shunting through transjugular intrahepatic portosystemic shunts (TIPS) can cause life-threatening hepatic encephalopathy and insufficiency. Intentional reduction of flow may be effective but difficult to control. The present report describes refinements of the parallel stent/stent-graft technique of flow reduction that is adjustable in either direction. Six patients underwent TIPS reduction with varying stent positioning and a variety of commercial products. Flow was adjusted by iterative balloon dilatation of the stent and stent-graft, resulting in a mean gradient increase of 8 mm Hg. All cases were technically successful, but 1-year survival was seen in only the patient who underwent liver transplantation.

Persistent and recurrent postsurgical varicoceles: venographic anatomy and treatment with N-butyl cyanoacrylate embolization.

PURPOSE: To elucidate the mechanism of persistence or recurrence of varicoceles after surgical repair by examining the venographic anatomy, and to review the efficacy of treatment of these patients with n-butyl cyanoacrylate (NBCA) embolization. MATERIALS AND METHODS: From 2001 to 2007, 17 patients with persistent or recurrent varicoceles were studied by retrograde venography 4 months to 18 years after open surgical repair. All patients were then treated with NBCA glue embolization of the entire gonadal vein and the venographically identified duplications and collateral vessels, with three patients undergoing bilateral procedures. Venographic anatomy and clinical success were retrospectively analyzed. RESULTS: The majority of patients (65%) exhibited duplications draining into a single left gonadal vein. Duplications were most frequently found to be confined to the pelvis and inguinal canal. Communication with other retroperitoneal veins, including the renal hilar, lumbar, iliac, and circumaortic renal vein, was relatively uncommon. NBCA embolization effectively treated the main gonadal vein as well as the duplications and communications, with only one patient developing thrombophlebitic complications. CONCLUSIONS: Duplication of the gonadal vein in the pelvic or inguinal region with apparent incomplete ligation or resection is a common finding in patients with persistence or recurrence of varicocele after surgery. NBCA embolization effectively treats these duplicated vessels, resulting in a high rate of clinical success on short-term follow-up.

Comparison of a new polytetrafluoroethylene-covered metallic stent to a noncovered stent in canine ureters.

The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30-40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15 weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted.

Portosystemic pressure gradient during transjugular intrahepatic portosystemic shunt with Viatorr stent graft: what is the critical low threshold to avoid medically uncontrolled low pressure gradient related complications?

BACKGROUND: Inappropriately decreased portosystemic pressure gradient (PSG) during transjugular intrahepatic portosystemic shunt (TIPS) can cause fatal complications but the critical low threshold of PSG is still not clear. The aim of the present study was to evaluate the critical low threshold of PSG during TIPS. METHODS: Sixty-six patients with cirrhosis who successfully underwent de novo TIPS with Viatorr stent grafts were studied. Medically uncontrolled low pressure gradient (LPR) complication was defined as when a patient died, or when acute transplantation or a TIPS reduction procedure was performed due to refractory encephalopathy or the deterioration of hepatic function within 3 months after the procedure. For the determination of the risk group for medically uncontrolled LPR complications, the Child-Pugh score and the model of end-stage liver disease (MELD) score showing a 100% negative predictive value was decided on as a threshold for each score. The risk group was defined when either of both scores was higher than its threshold. For the determination of a critical low post-TIPS PSG, a value of post-TIPS PSG showing the highest discrimination power on the receiver operating characteristic (ROC) curve in the risk group was decided on as a critical low threshold of PSG. The medically uncontrolled LPR complication rates of the patients with the determined threshold or lower were evaluated for the risk group. RESULTS: Medically uncontrolled LPR complications developed in nine patients (13.6%). Five patients died and four patients had TIPS reduction procedures. Patients with more than 10 on the Child-Pugh score or more than 14 on the MELD score were determined to be the risk group and 34 patients were included. The critical lower threshold of the post-TIPS PSG showing the highest discrimination power on the ROC curve was 5 mmHg (sensitivity 100%, specificity 72%), and the medically uncontrolled LPR complication rates of the patients with 5 mmHg or lower on the post-TIPS PSG were 56.3% (9/16) in the risk group. CONCLUSIONS: The critical threshold of the post-TIPS PSG to avoid the medically uncontrolled LPR complications of TIPS was >5 mmHg. The PSG should not be reduced below this level in the risk group.

Retrieval of trapped Günther Tulip inferior vena cava filters: snare-over-guide wire loop technique.

The Günther Tulip inferior vena cava (IVC) filter is designed for transjugular retrieval with use of a sheath and snare device. This report describes a technique for removal of difficult-to-retrieve Günther Tulip IVC filters when the standard method fails. In a series of four patients, each with an IVC filter refractory to capture by snare alone, the use of a snare-over-guide wire loop technique succeeded in retrieving the filter in all cases.

Transjugular intrahepatic portosystemic shunt creation in a polycystic liver facilitated by hybrid cross-sectional/angiographic imaging.

Polycystic liver disease (PCLD) has long been considered to represent a contraindication to transjugular intrahepatic portosystemic shunt (TIPS) creation, primarily because of the risk of hemorrhage. Three-dimensional (3D) navigation within the enlarged and potentially disorienting parenchyma can now be performed during the procedure with the development of C-arm cone-beam computed tomography, which relies on the same equipment already used for angiography. Such a hybrid 3D reconstruction-enabled angiography system was used for safe image guidance of a TIPS procedure in a patient with PCLD. This technology has the potential to expedite any image-guided procedure that requires 3D navigation.

Successful transfemoral creation of an intrahepatic portosystemic shunt with use of the Viatorr device.

Although the large majority of cases are anatomically favorable and therefore technically feasible, congenital or acquired conditions may complicate or even preclude successful creation of a transjugular intrahepatic portosystemic shunt (TIPS). The present report describes the use of the inferior right hepatic vein from a femoral vein access to obtain portal access and place a covered stent, reconstruct a partially occluded portal vein, and embolize large gastric varices in a patient with a persistent left superior vena cava (SVC) and absent right SVC.

Treatment of hepatic venous outflow obstruction after piggyback liver transplantation.

PURPOSE: To evaluate retrospectively the endovascular management of hepatic venous outflow obstruction after piggyback orthotopic liver transplantation. MATERIALS AND METHODS: The study was performed with the approval and under the guidelines of the institutional review board and complied with the Health Insurance Portability and Accountability Act. Informed consent from patients was not required by the institutional review board for this retrospective study. From 1995 to 2003, 13 patients (eight male, five female), including 12 adults and one adolescent (age range, 14-67 years; median age, 52 years), underwent endovascular treatment of hepatic venous outflow obstruction after piggyback orthotopic liver transplantation. Patients gave informed consent for all procedures. Eleven patients received whole livers, and two received living-related donor right liver lobes. Four underwent repeat piggyback orthotopic liver transplantation prior to intervention. Primary stent placement was performed in 12 patients. One patient refused primary stent placement and chose venoplasty alone, but required a stent 5 months later. Short balloon-expandable stents (mean diameter, 14.6 mm +/- 1.1 [standard deviation]) were used to minimize jailing of branch vessels and to resist recoil. Pre- and post-procedural pressure gradients were measured. Follow-up included venography, cross-sectional imaging, and laboratory tests. The Wilcoxon signed rank test or the sign test was performed to compare pre- and post-procedural pressure gradients, body weights, and laboratory values. RESULTS: Technical success (pressure gradient < or = 3 mm Hg) was achieved in 13 of 13 patients, and clinical success, in 12 of 13. Mean pre- and post-procedural pressure gradients were 13.0 mm Hg +/- 1.4 and 0.8 mm Hg +/- 0.3. Mean interval from transplantation to intervention was 348 days +/- 159. Mean follow-up was 678 days (range, 16-2880 days). Technical success did not result in clinical improvement in one patient. Biopsy demonstrated severe hepatic necrosis, likely from prolonged venous congestion, and the patient required repeat transplantation. Only one patient required reintervention for stent migration, and no other complications occurred. No significant restenosis was encountered after stent placement. CONCLUSION: Hepatic venous outflow obstruction is an uncommon but potentially fatal complication of piggyback orthotopic liver transplantation. Endovascular treatment with balloon-expandable stents is effective, safe, and apparently durable.

Stent-graft treatment of extracranial carotid and vertebral arterial lesions.

Five patients with pseudoaneurysms of the carotid artery (n = 4) and an arteriovenous fistula of the vertebral artery (n = 1) were treated with stent-grafts. Commercially made devices were used in all but one of the patients. In four of the five patients, the pathology was successfully excluded. One patient had a small type-I endoleak. There were no immediate procedure-related complications or neurologic sequalae. All experienced immediate resolution of symptoms. One patient was lost to follow-up after discharge and another died 2 weeks after intervention. The remaining patients remained asymptomatic with patent stent-grafts after follow-up periods of 14, 16, and 46 months, respectively.

TIPS reduction with use of stents or stent-grafts.

This report describes new techniques to perform TIPS reduction in patients with post-TIPS complications. Methods included hourglass-shaped stents and stent-grafts, and parallel stents and stent-grafts. All procedures were technically successful, resulting in increased portosystemic gradients and decreased symptoms, although patient outcomes were mixed. None of the patients experienced recurrent variceal hemorrhage or ascites in short-term follow-up. Stent-grafts have the advantage of immediate exclusion of blood flow outside the reducing stent, resulting in an immediate reduction of the caliber of the shunt. Techniques that allow fine adjustment of shunt diameters may have further advantages.

Transcatheter embolization for the treatment of upper gastrointestinal bleeding.

Over the past 20 years, the treatment of upper gastrointestinal bleeding (UGIB) that is refractory to endoscopic treatment has been revolutionized by transcatheter embolization. Embolization techniques have evolved with the use of microcatheters and new embolic materials. The majority of patients are successfully treated by minimally invasive techniques and can avoid having surgery.

Mechanical thrombectomy for the treatment of lower extremity deep vein thrombosis.

Deep venous thrombosis (DVT) has potentially debilitating long-term sequelae if left untreated. Conventional treatment (systemic anticoagulation with heparin followed by coumadin or low molecular weight heparin) often does not adequately relieves clot burden or symptoms, and patients may be left with post-thrombotic syndrome. Although the advent of catheter-directed thrombolysis has markedly improved the treatment of DVT and long-term outcomes of patients treated for DVT, it remains only partially effective on subacute or chronic clot. Mechanical thrombolysis may work synergistically with catheter-directed thrombolysis to decrease clot burden, treatment time, and complication rates, thereby improving outcomes.

Phase Fluorometry Using a Continuously Modulated Laser Diode.

The authors report phase fluorometrlc measurements using directly amplitude-modulated 670- and 791-nm laser diodes as the excitation source. Fluorescence lifetimes ranging from 220 ps to 1.7 ns were measured using a commercial phase fluorometer. It was found that higher amounts of radio frequency power were required to achieve comparable degrees of modulation when the dc current on the diode was Increased and that rf power above a certain level created distortion In the light output. Results are shown for common cyanlne laser dyes emitting at wavelengths to 840 nm.