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F S Keller

Publications and source records attributed to F S Keller.

At least 19 recordsLinked to original sources
PubMed2005

Small intestinal submucosa sandwich Zilver stent-grafts for TIPS: experimental pilot study in swine.

The aim of this study was the evaluation of preliminary suitability of the piglet small intestinal submucosa (SIS) sandwich Zilver endograft for experimental transjugular intrahepatic portosystemic shunt (TIPS) creation. TIPS was created in six swine. The five surviving animals underwent the follow-up portogram and were sacrificed at four weeks after TIPS creation. Gross and histologic examination was performed in all animals. TIPS creation was successful in all animals. One animal died four days after TIPS creation. In the five surviving animals, one shunt was occluded and four shunts were stenosed on the follow-up portogram. The mean percentage narrowing of the most advanced stenoses was 72% (range, 60%-100%). The most advanced stenosis was located in the parenchymal tract in three shunts and in the hepatic vein portion in one shunt. Gross and histologic examination showed abundant neointimal formation composed mainly of fibroblasts leading to the significant shunt stenoses. The piglet SIS sandwich Zilver stent-graft was found to offer only limited TIPS patency and should not be used for the definitive long-term TIPS study.

Journal Article↗
PubMed2002

Late complications and shape changes of the endografts after gigantic thoracic aortic aneurysm repair over a 7-year follow-up.

This report details a 7 years follow up observations in a 71-year-old patient treated with custom made endograft for gigantic thoracic aortic aneurysm (TAA). Progressive changes of the thoracic aorta and aneurysm after endograft placement led to two late complications including proximal stent graft prolapse into the aneurysm and extreme kinking of the endograft and aorta 28 and 51 months after treatment, respectively. Both complications were successfully treated with new endografts placement. Percutaneous endovascular repair is a promising, minimally invasive alternative to exclude TAA. This technique allows long-term treatment of patients who are unsuitable for conventional surgical procedures.

Aged↗
PubMed2001

Transjugular intrahepatic portosystemic shunt: present status, comparison with endoscopic therapy and shunt surgery, and future prospectives.

During the 13 years since its introduction into clinical practice, transjugular intrahepatic portosystemic shunt (TIPS) has become widely accepted worldwide as a percutaneous, interventional procedure for treating complications of portal hypertension. An experienced, skillful team, however, is necessary to ensure the high technical success of TIPS and to avoid its potential procedural complications. Presently, TIPS is used mainly for treatment of acute or recurrent hemorrhage from gastroesophageal varices refractory to endoscopic therapy. Randomized studies have shown that it is more effective than endoscopic treatment for preventing rebleeding; however, it is associated with a higher incidence of encephalopathy. Both treatments produce comparable survival rates. TIPS is also effective in the treatment of hepatogenic ascites and hydrothorax and hepatorenal syndrome. In comparison with surgical shunts, TIPS is a significantly less invasive procedure that can be done in poor surgical candidates with advanced cirrhosis. The high rate of shunt obstructions seen with TIPS mandates close surveillance and maintenance, rendering TIPS a multistage procedure. This is a major disadvantage of TIPS compared to surgery. Presently, both TIPS and surgical shunts have their place in the treatment of gastroesophageal variceal hemorrhage unresponsive to endoscopic therapy. TIPS is most suited for class B and C patients, particularly those who are candidates for liver transplantation. Surgical shunts should be considered for patients with well preserved liver function. Large, randomized controlled studies should be done to compare these treatment methods. Animal experimental and early clinical studies using covered stents (stent-grafts) are promising for the prevention of shunt obstructions and thus converting TIPS from a multistage to a one-stage procedure.

Animals↗
PubMed2001

Intravascular US-guided direct intrahepatic portacaval shunt with a PTFE-covered stent-graft: feasibility study in swine and initial clinical results.

PURPOSE: To determine the feasibility of the creation of a direct intrahepatic inferior vena cava (IVC)-to-portal-vein shunt with puncture guided by a transfemorally placed intravascular ultrasound (IVUS) probe and use of a polytetrafluoroethylene (PTFE)-covered stent-graft. MATERIALS AND METHODS: In five swine, transjugular access was used to perform a direct puncture from the IVC to the portal vein with use of a modified Rosch-Uchida Portal Access set directed with real-time IVUS (9 MHz) introduced from a transfemoral venous approach. The direct intrahepatic portocaval shunt (DIPS) was then created with single or overlapping PTFE-covered Palmaz stents placed through a 10-F sheath and dilated to a diameter of 8 mm. Follow-up was performed with transhepatic portography at 2, 4, and 8 weeks. Animals were killed when shunts occluded or at the termination of the study at 8 weeks. Gross and microscopic histologic study was performed on sacrificed animals. A similar technique was used to create DIPS in five patients with intractable ascites, with follow-up by US and venography. RESULTS: All experimental DIPS created in swine were created without complications. Portal vein punctures were achieved in four of five swine on the first or second pass of the needle. Follow-up transhepatic portography at 2 weeks demonstrated occlusion of two shunts, both explained by technical reasons at sacrifice. At 4 and 8 weeks, the remaining three shunts were patent on portography. Histology showed a thin neointimal lining with no significant tissue ingrowth or hyperplasia. Clinically, in five patients, successful puncture of the portal vein from the IVC was achieved in one to three passes. Creation of DIPS led to a reduction of mean portosystemic gradient from 18-29 mm Hg (mean, 24 mm Hg) to 9-10 mm Hg (mean, 9 mm Hg). One patient died of liver failure 2 days after creation of DIPS. The other four patients were doing well 2-15 months (mean, 8 months) after the procedure, with patency confirmed by US and venography. CONCLUSION: Creation of DIPS is technically feasible, and the direct IVC-to-portal-vein puncture can be done accurately with real-time IVUS guidance. Further studies and longer follow-up are necessary to determine if the short length of the PTFE-covered stent-graft and avoidance of the hepatic vein will increase the long-term patency compared to standard transjugular intrahepatic portosystemic shunt creation.

Animals↗
PubMed2001

Bifurcated drum occluder endograft for treatment of abdominal aortic aneurysm: an experimental study in dogs.

PURPOSE: To evaluate a new, low profile, home-made, bifurcated drum occluder endograft (BDOEG), designed for percutaneous, transcatheter treatment of abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: AAA was created in 10 dogs with over-dilated Palmaz stents. To prevent back filling, the lumbar arteries, inferior mesenteric artery, and common internal iliac arteries were embolized. The BDOEG was constructed of a drum occluder device and two PTFE endografts. The drum device consisted of a modified Z stent with Dacron stretched across and held within the ends of the stent, each with two 8 x 6-mm slits through which PTFE endografts were delivered. The PTFE endografts were 8 mm in diameter and 9.5 cm in length. Preloaded, the BDOEG was delivered through a 10-F sheath from both femoral arteries in a three-step procedure. All 10 animals were treated with BDOEG. Aortography was performed immediately, 6 weeks, and 12 weeks after stent-graft placement. Five animals were killed at 6 weeks and five were killed at 3 months. Gross and histologic evaluation was performed. RESULTS: The infrarenal aortic diameters and both external iliac arteries ranged from 8.0 mm to 10.3 mm (mean, 9.4 mm +/- 0.6) and from 5.2 mm to 6.8 mm (mean, 5.8 mm +/- 0.5), respectively. Creation of the AAA was successful in all 10 dogs. AAA diameters ranged from 13.7 mm to 15.9 mm (mean, 14.9 mm +/- 0.7). Complete exclusion of the AAA was achieved immediately after BDOEG placement and aneurysms remained excluded without perigraft leak to the time of killing in all 10 animals. There was a high incidence of aortoiliac limb occlusion. Occlusion of 12 aortoiliac limbs (60%) caused by intimal hyperplasia at the distal end of the endografts in iliac arteries developed in nine animals (90%). In six animals (60%), one limb occluded and, in three animals (30%), there was occlusion of both limbs. CONCLUSION: This study suggests a new approach for treatment of AAA. BDOEG use reduces sheath size for endograft delivery and may eliminate the need for a surgical cut down on femoral arteries. Tapering of the iliac ends of endografts to the size of the artery will be needed to prevent distal intimal hyperplasia.

Animals↗
PubMed2001

Anomalous left adrenal venous drainage directly into the inferior vena cava.

Primary hyperaldosteronism is a potential cause of hypertension. Unilateral adrenal adenoma and bilateral adrenal cortical hyperplasia are the most common causes of primary hyperaldosteronism. Adrenal venous sampling is employed as the gold standard test to differentiate between these two different causes when the results of other studies in the work-up protocol are non-diagnostic or ambiguous. Adrenal venous sampling can be a challenging procedure, especially in the presence of anomalous venous drainage patterns. Knowledge of normal adrenal venous anatomy, as well as possible variants, is therefore important to ensure a successful procedure. The authors describe an unusual variant of left adrenal venous drainage directly into the IVC.

Adrenal Gland Diseases↗
PubMed2000

The square stent-based large vessel occluder: an experimental pilot study.

PURPOSE: The purpose of this study is in vitro and in vivo experimental evaluation of a square stent-based vascular occlusion device for large vessels. MATERIALS AND METHODS: Square stent-based large vessel occluders (LVO) 5 mm-50 mm in size were constructed from stainless-steel square stents covered by porcine small intestine submucosa (SIS). The LVOs with two back-side barbs were delivered through a guiding catheter. The LVOs with two back-side barbs and two frontal barbs were front-loaded and delivered coaxially. A pusher with a retention mechanism at its end was used for deployment. In vitro testing for competency was performed with use of a flow model with pressure increases. In an experimental pilot study in seven pigs and five dogs, 16 LVOs were placed into the aorta (n = 4), common iliac artery (n = 2), pulmonary artery (n = 4), and medial sacral artery (n = 6). Four animals received two LVOs in different locations. Angiography was performed before and after placement of each LVO. Animals were followed for as long as 3 months with use of angiography and were then killed for gross and histologic evaluation. RESULTS: In vitro LVOs with two and four barbs were easily collapsed and pushed through or front-loaded into guiding catheters (6-F for a 5-mm occluder, 10-F for a 50-mm occluder). A 20-mm LVO adapted to tubular structures 10-15 mm in diameter, forming polygons 17-18.5 mm in length. In the flow model, LVOs endured pressure increases to 300 mm Hg. In vivo, the LVOs self-expanded and adapted to the vessel without migration in all cases. The locking pusher allowed precise LVO placement and engagement of its barbs into the vessel wall before complete deployment, preventing dislodgment by blood flow. Complete arterial occlusion occurred within 10-20 minutes and arteries remained occluded until the animal was killed in all cases. After 2 months, histologic evaluation revealed replacement of SIS by host tissue and its remodeling with variable fibrocytes, fibroblasts, and some inflammatory cells. Complete endothelialization was seen on both sides of the LVO. CONCLUSION: The SIS LVO is effective and reliable for acute and chronic occlusion in a high flow model in an experimental animal.

Angiography↗
PubMed1999

Twin-tube endografts for aortic aneurysms: an experimental feasibility study.

PURPOSE: To explore feasibility of twin-tube endografts (TTEGs) for treatment of abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: AAAs were created in six dogs by overdilation of Palmaz stents. TTEGs made of seven 9.5-mm-diameter Gianturco Rösch Z (GRZ) stents and covered with PTFE were deployed simultaneously from both femoral arteries through 10-F sheaths to exclude the AAA. Follow-up aortography was performed immediately and at 2, 4, and 8 weeks. Two dogs were killed at 4 weeks and four were killed at 8 weeks. Gross and histologic examinations were performed. RESULTS: AAA creation and TTEG placement were successful in all six dogs. TTEGs completely excluded AAAs in five dogs. Minor temporary perigraft leak was seen in one dog immediately after stent placement. Four dogs had TTEGs patent to termination at 8 weeks. In two dogs with oversized TTEGs, one of the twin endografts occluded at 2 weeks. At autopsy, TTEGs were formed in semicircular shape and histology did not show any significant inflammatory reaction. CONCLUSION: TTEGs show promise for treatment of AAA, with the potential of reducing the introductory sheath size. Further experimental studies, particularly with TTEGs extended into iliac arteries, are warranted.

Angiography↗
PubMed1998

Hepatic allograft abscess with hepatic arterial thrombosis.

BACKGROUND: Intrahepatic abscess (IA) is an uncommon complication after liver transplantation (OLTx) usually found in the setting of hepatic arterial thrombosis (HAT) often with associated biliary tree necrosis and/or stricture. Conventional treatment of IA in this setting has required retransplantation. METHODS: A retrospective review of 274 patients (287 OLTx) from September 1991 through September 1996 was performed. Median follow-up was 3.6 years. Diagnosis of HAT was confirmed by arteriography and IA was documented by computerized tomography. Percutaneous drainage of the abscess and stenting of biliary strictures, if present, was achieved using conventional interventional radiology techniques. RESULTS: The diagnosis of hepatic artery complication was made in 14 patients (5.1%), 2 of whom required retransplantation. Hepatic artery thrombosis associated with solitary IA was found in 3 patients (1%) who were transplanted in our center and in 1 additional patient followed up at our center but transplanted elsewhere. All 4 patients had complete resolution of IA using this approach. Three of the 4 patients are alive and well, with the fourth patient succumbing to recurrent hepatitis B infection resulting in allograft failure. CONCLUSIONS: Solitary hepatic allograft abscesses associated with HAT respond to percutaneous drainage and antibiotics, obviating the need for retransplantation in this setting.

Female↗
PubMed1998

Percutaneous retroperitoneal splenorenal shunt: an experimental study in swine.

PURPOSE: To evaluate the technical possibility of creating a percutaneous retroperitoneal splenorenal shunt (PRESS) in swine as a minimally invasive treatment of portal hypertension. MATERIALS AND METHODS: Five normal domestic swine underwent creation of a PRESS. A modified transjugular intrahepatic portosystemic shunt puncture set was introduced from the right femoral vein into the left renal vein. The proximal splenic vein was punctured transvenously through the retroperitoneal cavity. Noncovered metallic stents were then placed to connect both veins. The animals were sacrificed 1 hour after the procedure, after follow-up splenic venography and necropsy were performed. RESULTS: Puncture of the splenic vein and stent placement were successfully completed in all cases. In four of five cases, the splenic venogram revealed good flow from the splenic vein to the left renal vein through the shunt track 1 hour after creation of the PRESS, and there was no evidence of leakage. No changes in vital signs were noticed. At necropsy, a small retroperitoneal hematoma along the stent and minimal intraperitoneal bleeding were observed. The stents were found in the retroperitoneal cavity connecting both veins in all animals. CONCLUSION: Creation of a PRESS is technically possible, and further experimental studies of its efficacy are warranted.

Animals↗
PubMed1998

Transjugular intrahepatic portosystemic shunt patency and the importance of stenosis location in the development of recurrent symptoms.

PURPOSE: To analyze in detail the location and types of stenosis and occlusion that occur after transjugular intrahepatic portosystemic shunt (TIPS) creation and to determine the relative contribution of these various types of TIPS malfunction to recurrent symptoms of variceal bleeding or ascites. MATERIALS AND METHODS: In 116 of 217 patients who underwent TIPS creation between June 1990 and July 1995, follow-up portal venography was performed at 6-month intervals and for symptoms of recurrent variceal bleeding or ascites. RESULTS: Cumulative primary venographic patency by means of Kaplan-Meier survival analysis was 55% at 6 months and 5% at 2 years. Secondary patency was 92% at 2 years. Stenosis or occlusion occurred in 63 of 116 patients (54%). In 20 patients (17%), acute shunt occlusions developed less than 30 days after TIPS creation; in 24 patients (21%), tract abnormalities were detected after 30 days; and in 19 patients (16%), hepatic vein stenoses were detected after 30 days. Abnormalities of the parenchymal tract were more often correlated with recurrent variceal bleeding or ascites than were hepatic vein stenoses (odds ratio, 3.6; P = .02). Ten of 14 patients (71%) with detected biliary fistulas to their TIPS had symptoms, and all patients with biliary fistulas had tract abnormalities. CONCLUSION: Tract stenoses and occlusions were the major cause of symptomatic shunt failure after TIPS creation. Substantial bile duct transections are often associated with tract abnormalities and recurrent symptoms. Although common, hepatic vein stenoses were rarely associated with recurrent symptoms in our patient population.

Adult↗