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Biomedical subjects

A B Fontaine

Publications and source records attributed to A B Fontaine.

At least 19 recordsLinked to original sources
PubMed2001

Peripherally inserted central catheters with distal versus proximal valves: prospective randomized trial.

PURPOSE: To evaluate whether peripherally inserted central catheters (PICCs) with a proximal valve have any advantage compared to those with a distal valve in regard to the incidence of occlusion, infection, or malfunction. MATERIALS AND METHODS: One hundred patients (mean age, 46 y) were randomized to receive either a distal-valved Bard Groshong catheter (n = 48) or a proximal-valved Catheter Innovations Pressure Activated Safety Valve catheter (n = 52). All catheters were 4-F, single-lumen PICCs. Catheters were placed under fluoroscopic (n = 82) or sonographic (n = 18) guidance. Most (91%) were placed for the administration of antibiotics. The placement procedure, maintenance, and weekly follow-up were the same for both catheters. RESULTS: Percutaneous placement with the catheter tip in the central veins was successful in all patients. Mean dwell time was 36 days. There were 12 (25%) occlusive or infectious complications in the distal valve catheter group and six (11.5%) in the proximal valve group (P = .08). There were 25 fractures in 17 distal valve catheters (35.4%) and three (5.8%) proximal valve catheter fractures (P < .01). CONCLUSION: There was a marked difference in durability between the valved catheters, in favor of the catheter with a proximal valve. There was also a trend for fewer occlusive and infectious complications with the proximal valve catheter.

Adolescent↗
PubMed2001

Evaluation of local abciximab delivery from the surface of a polymer-coated covered stent: in vivo canine studies.

PURPOSE: To determine the in vitro feasibility of abciximab absorption and elution from a polymer-coated, silicone-covered stent, and to determine the in vivo effect of local delivery of abciximab concerning endothelialization of a polymer-coated, silicone-covered stent in a canine model. MATERIALS AND METHODS: Six polymer-coated, silicone-lined Wallstents were soaked in 2 mg/mL of concentrated solution of I131-labeled abciximab for a period as long as 48 hours. Quantification of abciximab absorption was determined by photon emission. Six maximally drug-loaded devices were then washed continuously with normal saline with use of a pustule pump apparatus. The quantity of residual abciximab was determined by photon emission for a period as long as 16 days. Eight similar devices (as described previously) were then implanted within the iliac arteries of four adult canines. Devices were identical except that four of eight were maximally loaded with abciximab. For each animal, one control implant was placed in the right iliac artery and one experimental implant (drug loaded) was placed in the left iliac artery, via right carotid cutdown. Animals were allowed to recover and no chronic medications were given. After an interval of 6 weeks, the animals were killed. Implants were isolated and perfused with 10% buffered formalin at a pressure of approximately 100 mm Hg for a period of 1 hour. Each implant was encased in methacrylate, sectioned into six equal segments, ground and polished, and stained with hematoxylin and eosin. Each slide was projected on a screen and the thickness of the neointima quantified. The mean neointima was determined for control and experimental groups, and compared for a potential significant difference with a Student t test. RESULTS: Mean absorption of abciximab was 21.53 microg +/- 2.99 per device. Devices were fully saturated at 24 hours. Forty percent was absorbed at 1 hour, and 60% and 80% were absorbed at 4 hours and 12 hours, respectively. Regarding elution, 30% of abciximab was washed out after 1 hour. There was a gradual elution of the drug to 16 days, with approximately 40% remaining at the end of the term. Mean neointimal thickness was 995 microm +/- 597 for the experimental group and 1,738 microm +/- 1,042 for the control group. The difference was significant (P <.05). CONCLUSIONS: Absorption and elution of abciximab from the surface of a covered stent is feasible. Local delivery of abciximab from the surface of this covered stent reduced the thickness of endothelial lining in the canine iliac artery compared to control.

Abciximab↗
PubMed2001

Seat belt aorta: endovascular management with a stent-graft.

PURPOSE: To report the endovascular treatment of a relatively uncommon type of deceleration injury to the abdominal aorta. CASE REPORT: A 21-year-old backseat passenger was wearing a single lap belt without shoulder harness when the car was involved in a collision. He sustained a transverse (Chance) fracture of the third lumbar vertebra and a circumferential dissection of the infrarenal abdominal aorta with pseudoaneurysm. As an interim measure while a stent-graft was obtained, a Wallstent was deployed to tack down the dissection and prevent distal embolization. Thirty-six hours later, an AneuRx endograft was successfully implanted inside the Wallstent to seal the pseudoaneurysm. The patient's recovery was uneventful, and the endograft remains secure and the pseudoaneurysm excluded at 10 months after the accident. CONCLUSIONS: Endovascular repair of "seat belt aorta" is a minimally invasive, straightforward method of management for this type of aortic injury. The potential for infection in a contaminated peritoneal cavity and the long-term outcome of this treatment have not been determined.

Adult↗
PubMed2000

Primary placement of Palmaz long medium stents in transjugular intrahepatic portosystemic shunts.

PURPOSE: To describe our results with primary placement of the long-medium Palmaz stent for transjugular intrahepatic portosystemic shunts (TIPS). MATERIALS AND METHODS: Between December 1997 and December 1998 primary placement of long-medium Palmaz stents was performed for TIPS procedures in 17 patients. Patency was determined with ultrasound, angiography, or pathologic examination in the event of transplant. RESULTS: Primary patency was achieved in 13 of 17 patients (76.5%) (follow up, 1-399 days; mean, 99 days). Secondary patency was achieved in 17 of 17 patients (100%) (follow-up, 1-399 days; mean, 110 days). Among the four patients who required revision, the mean time to revision from initial shunt creation was 81 days (range, 13-125 days). Two of these four patients had symptoms of worsening ascites as well as abnormal ultrasound findings prior to their revision; the other two patients were asymptomatic and had abnormal ultrasound findings only. Revisions were performed for intimal hyperplasia within the stent in three of the patients and acute thrombus within the stent in the remaining patient. Kaplan-Meier survival analysis for primary patency yielded mean survival time of 265 days (standard error, 52 days). CONCLUSION: The long-medium Palmaz stent is a viable stent for creation of TIPS shunts.

Ascites↗
PubMed1999

Treatment of inferior vena cava anastomotic stenoses with the Wallstent endoprosthesis after orthotopic liver transplantation.

PURPOSE: To evaluate the efficacy of the Wallstent endoprosthesis for treatment of stenotic or occlusive inferior vena cava (IVC) lesions refractory to balloon angioplasty in patients after orthotopic liver transplantation. MATERIALS AND METHODS: Wallstent endoprostheses were implanted in six patients with IVC anastomotic stenoses or occlusions that were refractory to balloon angioplasty. Follow-up included both duplex ultrasound (US) and clinical evaluations. RESULTS: Ten stents were successfully implanted in six patients. Five of six patients (83%) demonstrated primary patency on duplex US for a mean period of 11 months (range, 4-17 months). One patient's symptoms recurred within 3 weeks after intervention. This patient underwent repeated stent placement. Follow-up duplex US in this patient demonstrated primary assisted patency at 7 months. Mean clinical follow-up was 12 months (range, 7-18 months). Other than the previously described case, no patient developed recurrent symptoms of IVC stenosis or occlusion. Two patients who experienced hemorrhagic complications secondary to anticoagulation were treated successfully. CONCLUSIONS: The Wallstent endoprosthesis is a useful adjunct for treatment of IVC stenosis or occlusions in patients who have undergone orthotopic liver transplantation when these lesions are refractory to simple balloon angioplasty.

Adult↗
PubMed1999

Transcatheter arterial embolization for intractable epistaxis secondary to gunshot wounds.

PURPOSE: To evaluate the efficacy of transcatheter arterial embolization for intractable epistaxis secondary to gunshot wounds. MATERIALS AND METHODS: Seven patients with intractable epistaxis secondary to penetrating trauma (gunshot wounds) were studied with angiography and subsequently underwent embolization with particles (polyvinyl alcohol, gelatin sponge) and/or microcoils. Clinical follow-up included standard hemodynamic monitoring, serial hematocrit determinations, and clinical observation for recurrent bleeding. RESULTS: Diagnostic angiography demonstrated evidence of acute arterial injury in all patients. All patients subsequently underwent embolization to complete angiographic stasis. Two patients had persistent bleeding following embolization. One of these patients required maintenance of his nasal packing for 7 days after embolization; no blood products were required during this time. The second patient's bleeding resolved following correction of his coagulopathy. No complications occurred in any of the patients. CONCLUSIONS: Transcatheter arterial embolization for epistaxis secondary to gunshot wounds is efficacious in the acute setting when conservative management fails.

Adult↗
PubMed1999

Prospective randomized comparison of valved versus nonvalved peripherally inserted central vein catheters.

OBJECTIVE: The purpose of this study was to evaluate whether a valved peripherally inserted central catheter (PICC) design would result in a lower incidence of occlusion, infection, and malfunction than a clamped catheter. SUBJECTS AND METHODS: Three hundred sixty-two study patients (233 men, 129 women; mean age, 44 years) were randomized to receive a clamped (n = 182) or valved (n = 180) 5-French single-lumen PICC. Catheters were placed under fluoroscopic (n = 331) or sonographic guidance (n = 31). The valved PICC was flushed with saline solution, and the clamped PICC was flushed with a heparin-saline solution. All patients were prospectively followed up at least weekly for catheter status and complications. RESULTS: Percutaneous placement with the catheter tip in the central veins was successful in 99% of patients. Mean dwell time was 34 days. Twenty-six occlusive or infectious complications occurred in the clamped catheter group and 12 in the valved catheter group (p = .02). The clamped and valved catheter groups had 13 and five occlusions, respectively (p = .06), and 12 and five catheter-related blood stream infections, respectively (p = .09). Most occlusions (68%) were treated successfully with urokinase, and site infection or sepsis was treated by catheter removal. CONCLUSION: We found a statistically significant difference in the complication rate for the valved PICC compared with the clamped PICC. With the valved PICC, occlusion and infection were reduced, and patients having these catheters did not require heparin flushes.

Adult↗
PubMed1997

Renal artery dissection causing renal infarction in otherwise healthy men.

Arterial dissection is usually associated with pathological states such as malignant hypertension, severe atherosclerosis, severe trauma, Marfan syndrome, or Ehlers-Danlos syndrome. However, we report three cases in which renal artery dissection occurred in otherwise healthy, normotensive men. In two cases, the onset of symptoms of renal artery dissection was coincident with an unusual degree of physical activity. In the third case, the symptoms occurred while the patient was sitting but during a stressful business meeting. In each case, the patient experienced severe unilateral flank pain. Urolithiasis was suspected, but intravenous pyelography showed only ipsilateral impaired renal cortical perfusion, and the urinalyses showed no hematuria. The diagnosis of renal artery dissection was established by arteriography in two cases and by nephrectomy in one case. The latter case showed fibromuscular dysplasia by arteriography performed after the nephrectomy. The other two cases showed no evidence of fibromuscular dysplasia. We conclude that spontaneous renal artery dissection can occur in otherwise healthy individuals. Our experience and the reports of others indicate that this condition occurs mainly in men, conservative (nonsurgical) management is generally indicated, and the long-term prognosis is generally excellent. In some patients, an unusual degree of physical exertion might be the cause of renal artery dissection.

Adult↗
PubMed1997

Renal artery origins: best angiographic projection angles.

PURPOSE: To determine the best projection angles for imaging the renal artery origins in profile. MATERIALS AND METHODS: A mathematical model of the anatomy at the renal artery origins in the transverse plane was used to analyze the amount of aortic lumen that projects over the renal artery origins at various projection angles. Computed tomographic (CT) angiographic data about the location of 400 renal artery origins in 200 patients were statistically analyzed. RESULTS: In patients with an abdominal aortic diameter no larger than 3.0 cm, approximately 0.5 mm of the proximal part of the renal artery and origin may be hidden from view if there is a projection error of +/-10 degrees from the ideal image. A combination of anteroposterior and 20 degrees and 40 degrees left anterior oblique projections resulted in a 92% yield of images that adequately profiled the renal artery origins. Right anterior oblique projections resulted in the least useful images. CONCLUSION: An error in projection angle of +/-10 degrees is acceptable for angiographic imaging of the renal artery origins. Patients sex, site of interest (left or right artery), and local diameter of the abdominal aorta are important factors to consider.

Angiography↗
PubMed1996

Polymeric surface modifications of tantalum stents.

PURPOSE: To compare two kinds of polymer-coated tantalum stents with bare tantalum stents (control) to determine if the coatings can improve thromboresistance. METHODS: Twenty-seven Fontaine-Dake stents were balloon expanded in three 8-mm x 80-cm polytetrafluoroethylene (PTFE) grafts; 9 stents were bare tantalum (T); 9 were coated with polyetherurethane (PL); and 9 were coated with parylene (PA). There were 9 stents placed in each graft as follows: 3 tantalum, 3 polyetherurethane, and 3 parylene. In swine whose platelets had been radiolabeled with indium 111, the ends of each stented graft were connected to 14F femoral and venous sheaths to create an ex vivo fistula. Each graft was exposed to blood for 30, 60, and 120 minutes. At the end of each test period, the stented grafts were disconnected from the sheaths, flushed with saline until clear, and then flushed with formalin. The stents were removed from the grafts, and a radionuclide well counter recorded radionuclide counts from each stent type at each period of blood contact. These values were converted to platelet density per 1000 microns 2. Stents were then photographed and scanned with electron microscopy (EM) for qualitative analysis. Possible significant differences in platelet adhesion with the three types of stents (both between stent groups and within stent groups) were examined using a two-tailed Student's t-test. RESULTS: There were significantly fewer platelets adsorbed on PA versus T at all time periods (p < 0.005); on PL versus T at 60 and 120 minutes (p < 0.005); and on PA versus PL at 30 and 120 minutes (p < 0.0005). There was no significant difference in platelet density within each stent group (p = 0.1). Mean platelet density (number of platelets per 1000 microns 2 +/- SD) was as follows: at 30 minutes: T = 1891 +/- 965; PL = 373 +/- 193; and PA = 27 +/- 3; at 60 minutes: T = 6226 +/- 1621; PL = 1573 +/- 793; and PA = 1185 +/- 710; at 120 minutes: T = 5307 +/- 591; PL = 3164 +/- 318; and PA = 180 +/- 100. Gross inspection of the 120-minute groups demonstrated focal areas of thrombus on T, less on PL, and none on PA. Scanning EM demonstrated extensive platelet accumulation covering T at all time periods, less on PL, and even less on PA.

Animals↗
PubMed1995

Use of polyetherurethane to improve the biocompatibility of vascular stents.

PURPOSE: To investigate potential differential growth on neointima following overdilating arterial trauma with polyetherurethane-coated versus bare metallic stents in swine. METHODS: Twelve specially constructed tantalum stents, 6 coated with polyetherurethane block copolymer and 6 uncoated, were overdilated by 25% in 12 normal renal arteries of six swine. The stents were harvested 8 weeks after implantation and prepared for histologic examination. Neointimal thickness was quantified and analyzed for significant differences between coated and uncoated prostheses. RESULTS: All specimens demonstrated fractures of the internal elastic lamina consistent with vascular injury. There was significantly less neointimal formation (0.0001 < p < 0.05) in coated specimens as compared to uncoated controls in each test animal. CONCLUSIONS: The vascular response to overdilating stent trauma appears to be moderated with the use of polyetherurethane block copolymer as compared to control.

Animals↗