The Safety and efficacy of a new self-expandable intratracheal nitinol stent for the tracheal collapse in dogs

To evaluate the potential utility of a self-expandable intratracheal nitinol stent with flared ends for the treatment of tracheal collapse in dogs, endotracheal stenting therapy was performed under fluoroscopic guidance in four dogs with severe tracheal collapse. During the 4 to 7 month follow-up, after stent implantation, clinical signs, including dyspnea and respiratory distress, dramatically improved in all dogs. The radiographs showed that the implanted stents improved the tracheal collapse, and there were no side effects such as collapse, shortening or migration of the stents. In conclusion, the self-expandable intratracheal nitinol stents provided adequate stability to the trachea and were effective for attenuating the clinical signs associated with severe tracheal collapse.     

Intraluminal tracheal stent fracture in a Yorkshire terrier

An 8-year-old Yorkshire terrier was presented with tracheal collapse. Two intraluminal nitinol stents were implanted. The implanted stents were found to be fractured 4 weeks after implantation. The fractured stents were removed. To restore the collapsed trachea, ring prostheses were applied. However, the dog was euthanized because of a bad outcome following surgery.     

Choledochal tube stenting for decompression of the extrahepatic portion of the biliary tract in dogs: 13 cases (2002-2005)

OBJECTIVE: To determine clinicopathologic features, surgical management, complications, and long-term outcome associated with diseases of the extrahepatic portion of the biliary tract treated via choledochal stent placement in dogs. DESIGN: Retrospective case series. ANIMALS: 13 dogs. PROCEDURE: Data were obtained from medical records, and follow-up information was obtained via reexamination or telephone interview with owners or referring veterinarians. RESULTS: 10 dogs had extrahepatic biliary obstruction (EHBO), 6 as a result of pancreatitis. Two dogs had rupture of the common bile duct associated with cholelithiasis. In 1 dog, a stent was placed prophylactically after gastroduodenostomy was performed for a perforated duodenal ulcer. Nine of 13 dogs survived the perioperative period and were discharged. No recurrence of EHBO or other complications developed in the discharged dogs while the stents were in place. Median follow-up period from surgery to last owner contact was 13.3 months. In 1 dog, the stent was removed endoscopically 10 months after surgery and EHBO recurred 9 months after stent removal because of cholangitis. In 4 of 5 dogs that were discharged from the hospital, in which the fate of the stent could be confirmed and the stent was secured to the duodenal wall with absorbable suture materials, the stents were passed in the feces 1 to 11 months after surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Choledochal tube stenting is an effective method of decompression of the extrahepatic portion of the biliary tract in dogs and provides a less complex alternative to traditional cholecystoenterostomy techniques in select cases.     

Stent angioplasty for treatment of canine valvular pulmonic stenosis

Four dogs presented for evaluation and treatment of severe pulmonic valve stenosis and underwent stenting of the pulmonic valve annulus using bare-metal balloon-expandable stents. All dogs survived the procedure with immediate reduction of the transpulmonary valve pressure gradient and increase in activity levels. One dog had a stent fracture and migration 1 month after the intervention. This dog underwent a second procedure, in which multiple stents were used to alleviate the obstruction. The stents that were placed at the level of the right ventricular outflow tract fractured within 1 month of the procedure, and the patient died when a third (surgical) approach was attempted. The other three dogs remain alive 54, 42, and 29 months after the procedure. Stent angioplasty may be a viable option for dogs with valvular pulmonic stenosis in which routine balloon valvuloplasty does not provide a successful outcome. Aggressive attempts to diminish RVOT dynamic obstruction with high-dose beta blockade and avoiding deployment of the stent within the RVOT are recommended to prevent stent fracture and migration.     

Fracture of an endoluminal nitinol stent used in the treatment of tracheal collapse in a dog

A 5-year-old castrated male Pomeranian was evaluated because of severe dyspnea and coughing, and a diagnosis of complete, static collapse of the trachea at the thoracic inlet was made. After failure to improve with medical management alone, an endoluminal tracheal stent was placed, which resulted in resolution of signs. Ten weeks after stent placement, the dog underwent tracheal resection and anastomosis because the stent had fractured at the level of the thoracic inlet. One year after surgery, the dog was doing well and required treatment with hydrocodone infrequently. Compared with other surgical treatment options, placement of an endoluminal tracheal stent is a relatively noninvasive intervention that can provide effective relief from the clinical signs associated with tracheal collapse in dogs. Implantation of endoluminal tracheal stents may be associated with complications; therefore, the procedure may best be regarded as a salvage procedure for dogs with end-stage disease that are refractory to appropriate medical management, have extensive collapse of the intrathoracic portion of the trachea, or are poor candidates for surgery.     

Palatal erosion and oronasal fistulation following covered nasopharyngeal stent placement in two dogs

Treatment options for dogs with nasopharyngeal stenosis include fluoroscopic placement of metallic stents. Reported complications include entrapment of hair and food, obstruction and persistent nasal discharge. Two toy breed dogs were examined for persistent nasal discharge and halitosis at 4 and 20 months after placement of permanent metallic stents for acquired nasopharyngeal stenosis. Full thickness defects were found in the palate of both dogs, with extensive communication between the mouth and the nasal passages. Portions of the metal stent were observed within the lesion in both patients. Additional treatment was declined by the owner of one dog; the stent was removed through the fistula in the other dog. Palatal erosion with secondary oronasal fistulation is a potential complication of nasopharyngeal stent placement in dogs.     

Intraluminal tracheal stenting for treatment of tracheal narrowing in three cats

OBJECTIVE: To describe the use of intraluminal tracheal stenting in 3 cats with either benign or malignant tracheal obstruction. STUDY DESIGN: Retrospective clinical study. ANIMALS: Three client-owned cats. METHODS: Medical records were reviewed and information regarding signalment, clinical signs, physical examination findings, diagnostic tests performed, treatment, outcome and follow-up were retrieved. Intraluminal tracheal stent placement was performed as previously described in the literature. RESULTS: Three cats received intraluminal tracheal stents for the treatment of tracheal obstruction due to 3 different underlying causes: stricture secondary to traumatic endotracheal intubation, stricture secondary to a previous tracheotomy, and neoplasia. Self-expanding metallic stents of varying sizes were placed, and all cats recovered uneventfully from the procedures. The cat with tracheal neoplasia was euthanized because of pulmonary metastatic disease 6 weeks post-stent placement. The two cats with tracheal obstructions secondary to benign strictures are currently 39 months and 32 weeks post-stent placement, respectively. No complications were noted during the post-stent period in any of the 3 cats. CONCLUSIONS: Intraluminal tracheal stenting was easily, safely, and rapidly performed without complications and resulted in immediate improvement in clinical signs in all three cases. None of the cats in this study developed significant stent-associated complications during the study period. CLINICAL RELEVANCE: Intraluminal tracheal stenting has the potential to be a viable option for the treatment of tracheal obstruction in cats and perhaps for similar disease processes in other veterinary patients.     

Evaluation of the Palmaz Stent in the Trachea and Mainstem Bronchi of Normal Dogs

Objective — This study evaluates the efficacy of the Palmaz balloon expandable intraluminal stent in the trachea and mainstem bronchi of normal dogs. Study Design — Effects of the stent were evaluated by physical examination, thoracic radiography, respiratory tract fluoroscopy and endoscopy, tracheal diameter measurement, postmortem examination, and airway histomorphometry. Animals or Sample Population — Ten normal beagle dogs. Methods — Stent size was estimated from thoracic radiographs in awake dogs. Group I dogs (n = 4) had two stents placed: one in the thoracic trachea (TT) plus a randomly chosen mainstem bronchus (MB). Group II dogs (n = 3) had stents placed in the MB (one stent), TT (one stent), and mid- or proximal cervical trachea (CT) (one or two stents). Three dogs were used as sham-operated controls (group III). Temperature, pulse, respiration, and cough were measured twice daily. Dogs were evaluated at 21 and 49 to 56 days after stent placement, euthanatized, and tissues were collected for histomorphometric analysis of stent integration and epithelial pathology. Results — Mean tracheal diameters of awake (10.5 ±1.7 mm) and anesthetized dogs before stent implantation (13.9 ± 2.0 mm) were significantly different (P <.01). Complications associated with stent placement included acute pulmonary edema (n = 2), stent migration (n = 7), stent collapse (n = 4 CT, 2 TT, and 1 MB), and positive tracheal culture (n = 10). Group II dogs coughed more at rest, exercise, and with tracheal palpation than dogs in other groups (P <.01). Group I dogs coughed more at rest than group III dogs (P <.01). Stent integration ranged from 0 to 91.3%. Squamous metaplasia and epithelial ulceration associated with stents ranged from 0 to 57.5% and 0 to 32.7%, respectively. Conclusions — Determination of stent size should be based on measurements taken on anesthetized dogs because use of inappropriately sized stents may promote stent migration, squamous metaplasia, and/or ulceration. Epithelialization over stent struts may occur if the stent is closely associated with tracheal epithelium. Clinical Relevance — Palmaz stents do not appear to be appropriate for placement in the CT of dogs; however, with technical modifications, application in the TT and MB may be feasible.     

Recurrent single oesophageal stricture treated with a self-expanding stent in a cat

A 1-year-old, female spayed domestic shorthair cat was presented with a 4-week history of dysphagia and regurgitation soon after oral treatment with clindamycin. Fluoroscopic and endoscopic examinations confirmed the presence of a single cervical oesophageal stricture 4 cm caudal to the pharynx. A fluoroscopically and endoscopically guided balloon dilation was performed six times consecutively over a period of 3 weeks as reformation of the stricture appeared within 3-7 days. Feeding via percutaneous endoscopic gastrostomy-tube as long-term management of the condition was declined by the owner. A self-expanding metal oesophageal stent with the following dimension was subsequently implanted: fully open diameter 16 mm, length 30 mm. After stent implantation, the cat was fed on mashed canned food and did not show any clinical signs for 12 months. Twelve months post-implantation the cat was no longer able to eat even liquid food, became lethargic and the owner opted for euthanasia. On post-mortem examination the stent surfaces were overgrown by oesophageal mucosa by approximately 50%. Stent obstruction was detected and caused by swallowed hair which also seemed to have hampered mucosal integration in the distal part of the stent.     

Surgical repair of nasopharyngeal stenosis in a cat using a stent.

An intraluminal stent was used to maintain patency of a recurrent nasopharyngeal stenosis (NPS) in a cat. The stenotic membrane within the nasopharynx was resected, and a 2-cm long, braided-wire endoprosthesis was placed as a stent. The patient was evaluated at one day, six weeks, 19 weeks, and 49 weeks following surgery. The cat tolerated the stent well. The 19-week recheck revealed granulation tissue partially obstructing the pharyngeal aspect of the stent which was subsequently surgically resected. Complications after excision of the granulation tissue included intermittent upper respiratory congestion and nasal discharge. The 49-week recheck showed no increased granulation tissue; however, upper respiratory congestion was still present. This particular stent, and its use as described in this paper, is recommended in cases of chronic recurrent NPS.     

Palliative use of a stent for colonic obstruction caused by adenocarcinoma in two cats

CASE DESCRIPTION-Two adult male castrated cats were evaluated because of a history of constipation, tenesmus, or intermittent vomiting. CLINICAL FINDINGS-Radiography and ultrasonography revealed luminal narrowing in the colon of 1 cat and a colonic mass in the other. A histopathologic diagnosis of colonic adenocarcinoma was made in both cats. TREATMENT AND OUTCOME-Under fluoroscopic guidance, a self-expanding metallic stent was advanced over a wire and across the area of colonic stenosis and deployed. One cat had progressive weight loss but maintained a normal appetite, energy, and a high quality of life. Fecal continence was maintained, and tenesmus was rarely observed. The cat was euthanized because of tumor metastasis 274 days after the colonic stent was placed. The other cat retained fecal continence, and the owners reported subjective improvement in the severity of tenesmus, compared with that prior to stent placement. The cat was euthanized 19 days after stent placement because of perceived decreased quality of life. CLINICAL RELEVANCE-The use of self-expanding metallic stents for alleviation of colonic obstruction secondary to adenocarcinoma in cats appears to be effective. This technique provides a simple, quick, nonsurgical option for palliation in cats with advanced metastatic or systemic disease in which surgical resection may not be possible or warranted.     

Time course of reendothelialization of stents in a normal coronary swine model: characterization and quantification

Late thrombosis of coronary drug-eluting stents is an infrequent but serious complication of percutaneous transluminal coronary angioplasty. The best predictor of this event is the lack of endothelialization of stent struts. The objective of this study is to characterize and quantify the time course of endothelialization of different stents implanted in nonatherosclerotic swine coronary arteries. Thirty-three Carbofilm-coated stents were implanted percutaneously in 11 anesthetized domestic, crossbred pigs (weight 25 ± 3 kg, 2 months old). Each animal received 1 stainless steel stent (SS), 1 cobalt-chromium stent (CCS), and 1 tacrolimus-eluting stent (TES) in each coronary artery. Follow-up periods were 1 day (n = 9 stents), 3 days (n = 9 stents), and 7 days (n = 15 stents). Longitudinal sections of the stented vessels were examined using scanning electron microscopy. At 1 day, there was scarce, patchy endothelialization with areas of fibrin; the endothelialization rate was similar for all the stents (SS, 29% ± 23%; CCS, 29% ± 24%; TES, 31% ± 25%; P = .9). At 3 days, there were more endothelial cells but with immature features and giant cells over fibrin; the endothelialization was greater in SS and CCS than in TES (SS, 79% ± 14%; CCS, 81% ± 17%; TES, 46% ± 9%; P = .007). At 7 days, arteries showed better endothelialization with few giant cells; the endothelialization was greater in SS and CCS than in TES (SS, 95% ± 4%; CCS, 98% ± 4%; TES, 79% ± 9%; P = .01). In conclusion, the described model is useful for the analysis of endothelialization of coronary stents and facilitates measurement of its rate of formation and characterization of the involved cell types.     

Use of a biodegradable self-expanding stent in the management of a benign oesophageal stricture in a cat

An 11-year-old domestic shorthair cat presented with a six-week history of regurgitation following a dental procedure. Endoscopy identified a single oesophageal stricture in the cervical oesophagus. Stricture reformation occurred following endoscopic balloon catheter dilation on two occasions. Following a third balloon dilation a biodegradable polydioxanone self-expanding stent was placed across the stricture site. Following the implantation the cat was able to eat soft canned food orally without regurgitation. Fluoroscopic examination performed four months after placement indicated that the stent was no longer present and the cervical oesophagus was able to pass boluses of canned food with no signs of obstruction.     

Fluoroscopic stent placement for the relief of malignant urethral obstruction in a cat

The clinical features and interventional therapy in the case of a female cat with urinary tract obstruction secondary to neoplasia are presented. This form of neoplasia in cats is rare and therapeutic intervention to relieve urinary tract obstruction caused by malignancy has been described only once. This is the first report of a self-expandable metallic stent placed in a feline urethra to relieve obstruction caused by malignancy and the first report of the use of a unique composite metallic stent (Platinol™) in a cat. In conclusion, the palliative stenting of the feline urethra may be a valid therapeutic intervention for malignancies. Further studies are required to determine the optimal size and type of stent that will provide the greatest benefit.     

Use of a self-expanding metallic stent for the treatment of a urethral stricture in a young cat

A 4-month-old intact male domestic shorthair cat was evaluated for urinary outflow obstruction after several weeks of medical management for traumatic urethral rupture. Positive-contrast retrograde urethrography and anterograde cystoscopy performed 4 weeks after the initial urethral injury confirmed a stricture approximately 1cm distal to the bladder trigone at the site of the initial urethral tear. A self-expanding metallic urethral stent (SEMS) was placed under fluoroscopic guidance to relieve the urethral stricture and re-establish luminal patency. After stent placement, the cat was able to void urine normally with minimal urinary incontinence noted. This resolved several months post-stent placement. No known clinical complications persisted other than mild intermittent hematuria.     

Bilateral hydronephrosis secondary to endometriosis managed by endoscopic ureteral stent placement in a captive Guinea baboon (Papio papio)

Spontaneous endometriosis is an estrogen-dependent, progressive and painful disease that affects a variety of nonhuman primates, including several species of baboons (Papio sp.). This case documents multimodal management of severe endometriosis in a captive female baboon within a zoological institution. An 18-yr-old, intact female Guinea baboon (Papio papio) was found to have an enlarged uterus. Fifteen months post ovariohysterctomy, scarring associated with endometrial tissue resulted in ureteral strictures, bilateral hydronephrosis, and azotemia. Cystoscopic placement of bilateral ureteral stents with fluoroscopy was performed and resulted in short-term clinical improvement. The animal's condition declined and euthanasia was elected 4 mo after ureteral stent placement. Severe endometriosis with secondary inflammation resulting in bilateral hydroureter and hydronephrosis, as well as concurrent cystitis, ureteritis, and pyelonephritis were confirmed at necropsy. Despite possible complications, ureteral stents can be considered a useful therapeutic option in patients with ureteral disease.     

Self-expanding nitinol stents for the treatment of tracheal collapse in dogs: 12 cases (2001-2004)

OBJECTIVE: To evaluate long-term outcome following nitinol stent placement in dogs with tracheal collapse. DESIGN: Retrospective case series. ANIMALS: 12 client-owned dogs with endoscopically diagnosed tracheal collapse refractory to medical management. PROCEDURES: Medical records were reviewed for 12 dogs in which 1 or more self-expanding nitinol stents were placed for the treatment of endoscopically diagnosed tracheal collapse. A total of 17 stents were placed. RESULTS: Survival times after stent placement ranged from 1 to 48 months. Three of 12 dogs died within 6 months after stent placement. Nine dogs survived > 1 year after stent placement, and 7 dogs survived > 2 years. Of the deceased dogs, 5 of 9 succumbed to tracheal disease. Other causes of death included congestive heart failure, cerebral neoplasia, cerebrovascular accident, and renal failure. Material failure (stent fracture) was a common complication (5/12 dogs). Other complications reported included excessive granulation tissue within the stent lumen, tracheitis, and pneumonia. CONCLUSIONS AND CLINICAL RELEVANCE: Placement of an intraluminal stent with self-expanding nitinol stents was a successful palliative treatment for tracheal collapse in dogs that did not respond to medical management. Disease progression is inevitable, but substantial improvement in respiratory function may be achieved for a period of months to years.     

Etude Morphométrique de la Paroi de la Veine Cave Caudale après Implantation d'un Filtre chez le Mouton

The long stabilizers of the VT-LGM filter rest on large areas of the vascular wall. The morphometric study of the layers of the vascular wall, after implantation of filter in 15 ewes, divided into 3 groups of follow-up (2, 4 or 8 weeks) of 5 animals, was made at 3 levels opposite the filter and 1 level outside of it. Changes are seen for all the layers. Filter produces intimal hyperplasia. Stabilizers are quickly isolated from the blood flow. The thickness of the intimal hyperplasia grows for 4 weeks. It is more important at the base of the filter than at its head. There is also hyperplasia of the media with no change according to the follow-up or the level opposite the filter. The adventitia becomes thinner without variation of time or level of the filter. Smooth muscle cells of the adventitia become less frequent and smaller. Their density, in front of the stabilizers, is the smallest by 4 week follow-up and remains the same along the stabilizer. The full thickness of the wall is bigger opposite the stabilizers than between them. The filter produces changes that are limited in time and in space. The most important changes are seen at 4 weeks after insertion and opposite the stabilizers.     

Stenting of the right ventricular outflow tract in 2 dogs for palliation of dysplastic pulmonary valve stenosis and right-to-left intracardiac shunting defects

Two dogs with severe dysplastic pulmonary valve stenosis and right-to-left shunting defects (patent foramen ovale, perimembranous ventricular septal defect) underwent palliative stenting of the right ventricular outflow tract and pulmonary valve annulus using balloon expandable stents. One dog received 2 over-lapping bare metal stents placed 7 months apart; the other received a single covered stent. Both procedures were considered technically successful with a reduction in the transpulmonary valve pressure gradient from 202 to 90 mmHg in 1 dog and from 168 to 95 mmHg in the other. Clinical signs of exercise intolerance and syncope were temporarily resolved in both dogs. However, progressive right ventricular concentric hypertrophy, recurrent stenosis, and erythrocytosis were observed over the subsequent 6 months leading to poor long-term outcomes. Stenting of the right ventricular outflow tract is feasible in dogs with severe dysplastic pulmonary valve stenosis, though further study and optimization of the procedure is required.     

犬污染骨异位寄养再回植的影像学评估

[目的]探讨犬游离长段桡骨通过寄养在血运丰富的隐静脉旁使其血管化来修复开放性骨折造成的骨缺损的可行性。[方法]选取12只成年健康犬随机分为实验组与对照组,2组分别截取右侧前肢桡骨中段约15 mm的桡骨骨段。模拟车祸环境,将截取的长段桡骨放置于外界泥土中1 h,取回的骨块用大量生理盐水冲洗,并放置在10%聚维酮碘中浸泡5 min,之后使用生理盐水冲洗1 min,沥干备用。实验组将其包埋在血管丰富的隐静脉处,对照组放置于-80℃低温无菌保存。8周后取出骨块,植回原位修复犬桡骨骨缺损。回植后第6、12周观察桡骨的大体形态。第4、8、12周通过X射线观察修复效果,使用Lane-Sandhu X线评分标准进行评分。[结果]在同一时间段内,实验组桡骨骨缺损修复的效果均好于对照组。[结论]通过寄养血管化的长段骨和低温保存长段骨均可修复犬桡骨骨缺损,与-80℃保存的骨块相比血管化的长段骨具有愈合时间短、骨吸收少的优点。