nitinol and Fibrosis

This study was conducted to determine whether a nitinol stent coated with doxycycline prevents tracheal inflammation and fibrosis in a rabbit.. A nitinol stent coated with doxycycline was designed by us. Twelve rabbits were divided into three groups: normal, control (nondoxycycline-coated stent), and doxycycline-coated stent group. The stents were inserted into the tracheal lumen through the oral cavity. Tracheal granulation was evaluated and graded by laryngoscopy. Histological examinations evaluated the inflammatory response and fibrosis. Real-time polymerase chain reaction (PCR) and Western blot assessed the changes to the extracellular matrix (ECM).. Endoscopic findings showed that the nitinol stent coated with doxycycline resulted in lesser granulation tissue in the trachea than the noncoated stent. Histologic examination further revealed that the doxycycline-coated stent was associated with decreased inflammatory cells and reduced fibrosis, compared to the noncoated stent. In PCR and Western blot, the doxycycline-coated stent showed lower expression of ECM components inducing fibrosis.. A nitinol stent coated with doxycycline showed favorable effects in reducing tracheal inflammation and fibrosis in a rabbit model. Further research is required to study the beneficial effects of local application of doxycycline for prevention of tracheal stenosis.. NA. Laryngoscope, 128:1558-1563, 2018.

Topics: Adjuvants, Immunologic; Alloys; Animals; Anti-Bacterial Agents; Disease Models, Animal; Doxycycline; Fibrosis; Inflammation; Laryngoscopy; Rabbits; RNA, Messenger; Stents; Trachea; Tracheal Stenosis; Transforming Growth Factor beta1; Wound Healing

We aim to deliver large appliances into the left ventricle through the right ventricle and across the interventricular septum. This transthoracic access route exploits immediate recoil of the septum, and lower transmyocardial pressure gradient across the right versus left ventricular free wall. The route may enhance safety and allow subxiphoid rather than intercostal traversal.. The entire procedure was performed under real-time CMR guidance. An "active" CMR needle crossed the chest, right ventricular free wall, and then the interventricular septum to deliver a guidewire then used to deliver an 18Fr introducer. Afterwards, the right ventricular free wall was closed with a nitinol occluder. Immediate closure and late healing of the unrepaired septum and free wall were assessed by oximetry, angiography, CMR, and necropsy up to four weeks afterwards.. The procedure was successful in 9 of 11 pigs. One failed because of refractory ventricular fibrillation upon needle entry, and the other because of inadequate guidewire support. In all ten attempts, the right ventricular free wall was closed without hemopericardium. There was neither immediate nor late shunt on oximetry, X-ray angiography, or CMR. The interventricular septal tract fibrosed completely. Transventricular trajectories planned on human CT scans suggest comparable intracavitary working space and less acute entry angles than a conventional atrial transseptal approach.. Large closed-chest access ports can be introduced across the right ventricular free wall and interventricular septum into the left ventricle. The septum recoils immediately and heals completely without repair. A nitinol occluder immediately seals the right ventricular wall. The entry angle is more favorable to introduce, for example, prosthetic mitral valves than a conventional atrial transseptal approach.

Topics: Aged; Alloys; Animals; Cardiac Catheterization; Cardiac Catheters; Cardiovascular Diseases; Feasibility Studies; Female; Fibrosis; Heart Ventricles; Hemodynamics; Humans; Magnetic Resonance Imaging, Interventional; Male; Middle Aged; Models, Animal; Prosthesis Design; Punctures; Septal Occluder Device; Swine; Time Factors; Tomography, X-Ray Computed; Ventricular Function; Ventricular Septum; Wound Healing

To assess whether the use of a prosthesis covered by a Dacron sheath might prevent pseudointimal hyperplasia in a transjugular intrahepatic portosystemic shunt (TIPS).. A TIPS procedure was performed in nine pigs, after creation of a portal vein microembolization model of portal hypertension, by using a Dacron-covered nitinol stent. The first centimeter on the lower extremity of this specially made prototype was uncovered, to avoid portal vein thrombosis. Three weeks later, the seven surviving animals underwent transjugular hemodynamic and angiographic follow-up and were then killed for gross and histologic evaluation.. Shunt insertion was possible in all pigs; two died of complications of the procedure. After 3 weeks only two shunts were patent, although a 50%-60% narrowing of the initial portion of the shunt was present; the remaining shunts were occluded. Histologic examination showed pseudointimal hyperplasia associated, in the cases of occlusion, with a luminal thrombosis.. This Dacron-covered stent did not prevent pseudointima formation over the stent and resulted in a high early occlusion rate, probably related to a pronounced tissue fibrotic response likely due to Dacron-induced inflammation.

Topics: Alloys; Angiography; Animals; Disease Models, Animal; Embolism; Equipment Design; Fibrosis; Follow-Up Studies; Graft Occlusion, Vascular; Hemodynamics; Hepatic Artery; Hyperplasia; Hypertension, Portal; Polyethylene Terephthalates; Portal Vein; Portasystemic Shunt, Transjugular Intrahepatic; Stents; Surface Properties; Survival Rate; Swine; Thrombosis; Tunica Intima; Vascular Patency

To evaluate the short-term effects of a new nitinol stent on canine arteries.. Eighteen nitinol mesh stents were placed in abdominal aortas, common iliac arteries, and renal arteries of six dogs. Angiography was performed to evaluate the patency rates and structural changes of arteries at 1 day, 3 weeks, 4 weeks, and 10 weeks after stent insertion. Gross and light microscopic examinations were performed after angiography.. On angiography, the patency rate was 100%, and no thrombosis was observed. All side branches from stented segments were patent. The mean neointimal thickness over and between stent wires was 94 and 167 microns. No difference was found between the aorta and the small vessels. Histologically, the neointima was covered with endothelium and was composed of subintimal fibrosis with mild inflammation.. The new type of nitinol mesh stent showed a high patency rate, with no thrombosis and relatively thin neointimal proliferation.

Topics: Alloys; Angiography; Animals; Aorta, Abdominal; Biocompatible Materials; Dogs; Endothelium, Vascular; Fibrosis; Follow-Up Studies; Stents; Tunica Intima

To compare the nitinol occlusion plug with standard stainless steel coils for the occlusion of moderate-size peripheral veins.. The nitinol plug is a braided multilayered vascular occlusion device filled with thrombogenic polyester fibers. It is self-expanding and can be recaptured into its 6-F introducing sheath for repositioning prior to detachment. Ten occlusion procedures were performed in five dogs from a retrograde transjugular venous approach. Five nitinol plugs (diameter: 7.4 mm +/- 0.5) were deployed in five femoropopliteal veins (diameter: 6.5 mm +/- 0.7; mean oversizing 14.6%). Two sequential Gianturco coils (diameter: 7.4 mm +/- 0.9) were deployed in the corresponding contralateral veins (diameter: 6.2 mm +/- 0.8; mean oversizing 19.6%). Follow-up venography was performed at 1 month, following which the animals were killed and the vessels were explanted.. Time-to-occlusion was significantly shorter with the nitinol plug as compared to two Gianturco coils (4.2 minutes +/- 3.4 vs 25.6 minutes +/- 14.1, respectively [P < .03]). At 1 month all but one coil-doublet (80%) had recanalized or migrated, compared to only one nitinol occluder (20%, P < .04). Histopathologic examination of plug-occluded veins showed a uniform organized matrix and underlying intimal proliferative response.. A single nitinol occluder resulted in significantly faster occlusion time and significantly lower recanalization or migration rate than two Gianturco coils, in moderate-size peripheral veins.

Topics: Alloys; Animals; Collateral Circulation; Dogs; Embolization, Therapeutic; Equipment Design; Femoral Vein; Fibrosis; Follow-Up Studies; Foreign-Body Migration; Peripheral Vascular Diseases; Phlebography; Polyesters; Popliteal Vein; Stainless Steel; Statistics as Topic; Time Factors; Tunica Intima