nitinol and Foreign-Body-Reaction

Tumor ingrowth through self-expanding metal stents presents a difficult problem for management. The techniques for treating tumor ingrowth have not yet been well described, and the optimal endoscopic approach is not clear. We have recently used photodynamic therapy (PDT) to treat tumor ingrowth through uncovered nitinol mesh stents.. Four patients (mean age 73) with obstructive adenocarcinomas of the distal esophagus had received self-expanding stents for palliation of their dysphagia. After stent placement, tumor ingrowth had caused progressive dysphagia in all of the patients; the dysphagia was graded on a scale from 0 (normal) to 4 (inability to swallow liquids). All of the patients received PDT treatment.. After PDT, excellent palliation of the dysphagia was seen in all of the patients, with a mean improvement in the dysphagia score of 2.25 and a mean dysphagia-free interval of 92 days. There were no major complications.. The use of PDT to treat tumor ingrowth through self-expanding metal esophageal stents is effective and safe.

Topics: Adenocarcinoma; Aged; Aged, 80 and over; Alloys; Deglutition Disorders; Esophageal Neoplasms; Esophageal Stenosis; Esophagoscopy; Female; Foreign-Body Reaction; Hematoporphyrin Derivative; Humans; Male; Middle Aged; Palliative Care; Photochemotherapy; Photosensitizing Agents; Prognosis; Stents; Survival Rate

The study aimed to test a Nitinol(®)-based vein cuff model for external banding valvuloplasty.. In 12 adult minipigs, the vena jugularis externa was covered for 42 days by a cuff with an inner diameter adapted to the outer vein diameter in supine position. By changing from supine into prone position hypostatically vein dilation was induced to simulate varicose vein dilation. Cuff position and the inner diameter of the vein lumen under the cuff were examined by computer tomography scanning. Also, histological analysis of the vein wall within the cuff was performed.. The preset tubular shape of the cuff and the cuff position did not change in both prone and supine position, but due to fibrosis the luminal vein diameter within the cuff was decreased (P < 0.01) already after 21 days.. A foreign body response resulted in a fibrous capsule covering the cuff which might limit cuff functionality.

Topics: Alloys; Anesthesia; Animals; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Female; Foreign-Body Reaction; Swine; Swine, Miniature; Time Factors; Tomography, X-Ray Computed; Varicose Veins; Venous Insufficiency

We investigated the safety, feasibility and efficacy of the Occlutech devices for patent foramen ovale (PFO) and atrial septal defect (ASD) closure in a prospective trial.. The retention discs of the PFO device (23 x 25 mm, 27 x 30 mm) are connected by a 3 mm waist in the center with only one right atrial side central pin. The left atrial disc is produced either with a single or double flat layer, which allows a significant reduction of meshwork material. The ASD occluder (6-40 mm, 3 mm increments) has only one central pin on the right atrial side. Indications for closure included cryptogenic stroke with evidence of a PFO on transesophageal echocardiography (TEE) or an ASD II. The devices were implanted in 29 patients with PFO and in 12 patients with ASD II (fluoroscopy and TEE). An echocardiographic follow-up examination was performed after 1, 2 and 6 months.. The devices were successfully implanted in all 41 patients. There were no periprocedural complications. One patient with ASD II died of recurrent myocardial infarction without evidence of cardioembolic origin. TEE studies showed a residual shunt in 11.2% after 60 days in patients with PFO and a left-to-right shunt in 9.1% of the remaining patients with ASD II. After 180 days only 1 patient with PFO had a right-to-left shunt (3.7%). A residual shunt in the patients with ASD was not observed.. The novel Occlutech devices appear to be safe, feasible and effective for PFO and ASD closure, with a significant reduction of the meshwork and absence of left atrial central pin.

Topics: Adult; Aged; Alloys; Animals; Echocardiography; Echocardiography, Transesophageal; Equipment Failure Analysis; Equipment Safety; Feasibility Studies; Female; Foramen Ovale, Patent; Foreign-Body Reaction; Heart Septal Defects, Atrial; Humans; Male; Middle Aged; Myocardial Infarction; Postoperative Complications; Prosthesis Design; Septal Occluder Device; Swine; Swine, Miniature

Topics: Aged; Alloys; Echocardiography; Equipment Failure Analysis; Equipment Safety; Female; Foramen Ovale, Patent; Foreign-Body Reaction; Heart Septal Defects, Atrial; Humans; Male; Middle Aged; Myocardial Infarction; Postoperative Complications; Prosthesis Design; Septal Occluder Device

Gastrointestinal anastomosis is a crucial step in many operative procedures, and responsible for a major portion of early and late post-operative complications. In order to improve on the results of current tools to perform an anastomosis, such as sutures and staplers, new concepts are being developed. One of these concepts is compression anastomosis. Compression anastomosis has been tried in the past but did not become popular mostly because of technical reasons. Recently, trials to accomplish compression anastomosis using Nitinol devices were conducted. Two devices were made and tested in the past three years: a side-to-side device and an end-to-end device. The common principle in both devices is the compression of two bowel loops through the constant pressure of a Nitinol device, thus producing a dual process of necrosis and healing until the lumens of both bowels fuse, and the device falls into the lumen and is excreted. Both devices have been tested in animals and humans, with encouraging results. In animals, the anastomoses were shown to demonstrate minimal inflammation and no foreign body reaction, with perfect healing of the mucosa. The side-to-side device was tested in over 500 human patients, and the end-to-end device is currently used in a large, multi-centric human trial.

Topics: Alloys; Anastomosis, Surgical; Animals; Clinical Trials as Topic; Digestive System Surgical Procedures; Elasticity; Equipment Design; Foreign-Body Reaction; Humans; Inflammation; Postoperative Complications; Pressure; Suture Techniques

Topics: Alloys; Angioplasty, Balloon; Arterial Occlusive Diseases; Device Removal; Equipment Design; Femoral Artery; Foreign-Body Migration; Foreign-Body Reaction; Giant Cell Arteritis; Hemorrhage; Hemostatic Techniques; Humans; Patient Selection; Pressure; Punctures; Risk Factors; Skin Diseases; Ultrasonography

We report the first case of a transcutaneous migration of a vascular clip closure device 10 weeks after placement during femoral artery puncture for percutaneous transluminal angioplasty. We postulate focal inflammatory vascular wall changes as the predisposing factor in this patient with giant cell arteritis.

Topics: Aged; Alloys; Angioplasty, Balloon; Arterial Occlusive Diseases; Device Removal; Equipment Design; Female; Femoral Artery; Foreign-Body Migration; Foreign-Body Reaction; Giant Cell Arteritis; Hemorrhage; Hemostatic Techniques; Humans; Punctures; Risk Factors; Skin Diseases; Ultrasonography

Testing the safety and foreign body reaction (FBR) of a nitinol self-expandable carbon-coated stent system in the porcine animal model at different follow-up (FU) periods.. Fifteen minipigs received 30 carbon-coated self-expandable nitinol stents in iliac arteries. Explants were carried out at 7 (3 animals), 30 (4 animals), 90 (4 animals) and 180 (4 animals) day FU, for evaluation of acute, sub-acute and chronic biological response to the implanted devices. Histological, immunohistochemical, histomorphometric and scanning electron microscopy (SEM) analyses were performed to assess inflammatory reaction, endothelialization process, neointimal growth and cellular composition.. Thirty stents were successfully implanted. No mural thrombi were observed at gross examination or by angiography. Histologically no significant inflammatory reaction was detected: the stents appeared covered by a thin monolayer of endothelial cells even at 7 day FU. The neointima presented homogeneous growth and moderate thickness after 30, 90 and 180 days explants (0.38+/- 0.36 mm, 0.33+/- 0.30 mm, 0.27+/- 0.25 mm respectively). Internal and external elastic laminae were intact in 95% of stented arteries. Histological data validations of vessel endothelialization was obtained with SEM for the seven day follow-up group.. This study showed good remarkable technical performances, minimal FBR and biocompatibility comparable with other available pre-clinical experimentations.

Topics: Alloys; Animals; Foreign-Body Reaction; Immunohistochemistry; Microscopy, Electron, Scanning; Models, Animal; Stents; Swine; Swine, Miniature

To evaluate with magnetic resonance (MR) imaging the inflammatory perigraft response after implantation of Dacron-covered and noncovered arterial endovascular prostheses in sheep.. Four prosthesis types--two Dacron-covered nitinol stent-grafts (plain and heparin-coated) and two noncovered nitinol stents (Memotherm and Cragg)--were each inserted into the external iliac arteries of eight sheep. MR imaging before and after gadolinium enhancement was performed 5-8 days and 1 month after implantation (before the animals were killed). Macroscopic and microscopic examinations of the vessels were performed, and findings were correlated with those on MR images.. Severe inflammatory perigraft responses to the heparin-coated Dacron-covered stent-grafts were found; MR images demonstrated contrast enhancement and edema. Macroscopic examination showed marked vascular wall thickening and adhesions around the Dacron fabric; microscopic examination showed a pronounced inflammatory foreign-body response. There was a moderate inflammatory response to the plain Dacron-covered stent-grafts and almost no response to noncovered stents.. In sheep, MR imaging findings of perigraft soft-tissue edema and contrast enhancement correlated well with histopathologic findings of severe perigraft inflammation due to heparin-coated Dacron-covered stent-grafts.

Topics: Alloys; Animals; Blood Vessel Prosthesis; Foreign-Body Reaction; Heparin; Iliac Artery; Inflammation; Magnetic Resonance Imaging; Polyethylene Terephthalates; Sheep; Stents

To determine the biocompatibility and thrombogenicity of nitinol blood clot filters, we inserted 27 nitinol wire devices into the venae cavae of 16 dogs and one sheep and studied the results angiographically and at autopsy after periods of one week to four years. Filter shape, location in the vena cava, wire cleaning procedure and wire surface finish were varied. All 18 cleaned nitinol wire filters remained patent by venogram, although some showed small venographic filling defects caused by adherent organized thrombi. Filters in larger veins tended to have less thrombus. Surface polishing and filter shape had no observable effect on thrombogenicity. Histologic study revealed patchy chronic inflammation at the surface of uncleaned filters but only benign fibrous tissue reaction for the cleaned filters. Neointimal tissue overgrowth was observed where nitinol wire contacted the wall of the vena cava. Two filters implanted for four years had no appreciable weight loss caused by corrosion. Platelet adhesion and plasma coagulation effects of nitinol wire were tested in vitro in human blood and found to be similar to those of stainless steel, which is used in comparable devices. These encouraging results suggest that nitinol may be a promising material for human intravascular prosthetic applications.

Topics: Alloys; Animals; Biocompatible Materials; Dogs; Filtration; Foreign-Body Reaction; Pulmonary Embolism; Sheep; Thrombosis; Venae Cavae