Balloon-expandable Metallic Stent Research Articles

Clinical use of uncovered balloon-expandable metallic biliary stents for treatment of extrahepatic biliary tract obstructions in cats and dogs: 11 cases (2012-2022).

To describe the application of uncovered balloon-expandable metallic biliary stents for treatment of extrahepatic biliary obstructions (EHBOs) and the outcomes for dogs and cats treated for EHBO with this technique. Retrospective single institutional study. Eight dogs and three cats treated at the Veterinary Specialty Hospital of San Diego for EHBO between January 2012 and February 2022. Data collected from the medical records included signalment, presenting complaint, laboratory and imaging findings, surgical findings, hospitalization time, complications, and follow-up information. Median duration of short-term follow up was 16 days (6-45 days). Improved biochemical abnormalities and resolution of clinical signs were recorded in 10/11 cases. Two dogs died within 2 weeks of surgery. One dog developed systemic inflammatory response syndrome 5 days postoperatively and was euthanized; the cause of death in the second case was unknown. Long-term follow up was available in seven cases, with a median duration of 307.5 days (62-2268 days). Bile-duct patency was maintained for at least 356-622 days (median: 446 days) in three cats and 62-2268 days (median: 650.5 days) in four dogs with long-term follow up available. One cat had recurrent obstruction with choledocholiths 446 days postoperatively. One stent was removed 614 days postoperatively due to recurrent cholangiohepatitis. Uncovered balloon-expandable metallic biliary stents were placed successfully and relieved EHBO in all cases that survived to discharge. Use of uncovered balloon-expandable metallic biliary stents should be considered as an alternative to temporary choledochal luminal stenting or cholecystoenterostomy to manage EHBO.

Transjugular Intrahepatic Portosystemic Shunt

Transjugular intrahepatic portosystemic shunt (TIPS) is now a well established percutaneous means of decreasing portal hypertension. The major clinical indications for transjugular intrahepatic portosystemic shunt are refractory variceal hemorrhage and refractory ascites. The shunt itself is created by placing a stent between the portal vein and the hepatic vein. The resultant shunting of portal venous flow to the systemic circulation helps reduce the portosystemic gradient and alleviate bleeding and ascites without changing the extrahepatic anatomy. History and Development The transjugular intrahepatic portosystemic shunt was initially described in 1969, originally by prolonged balloon dilation of a percutaneously created tract between the portal and hepatic veins. Unfortunately, short patency of the track remained a major clinical hurdle to its widespread use. The development of balloon expandable metallic stents and the subsequent introduction of flexible bare-metal stents helped improve patency rates. Intimal hyperplasia within the stent, especially at the hepatic venous end, required frequent secondary interventions such as balloon dilation and re-stenting. Early thrombosis was felt to be secondary to placing the transjugular intrahepatic portosystemic shunt across a major bile duct. Advances in stent technology and the introduction of polytetrafluoroethylene-covered stents over a decade ago has led to further increase in clinical patency and improved long-term results with TIPS.

Transvalvular pulmonic stent angioplasty: procedural outcomes and complications in 15 dogs with pulmonic stenosis

IntroductionBalloon valvuloplasty is the treatment of choice for dogs with severe type A pulmonic stenosis (PS), but less successful for dogs with annular hypoplasia and unsuitable for supravalvular stenosis or cases with a circumpulmonary coronary malformation. We report outcomes and complications of the first 15 consecutive transvalvular pulmonic stent angioplasty procedures performed by a single center in dogs with PS. AnimalsFifteen dogs with naturally occurring PS were included in the study. Materials and methodsDogs underwent echocardiography before and four weeks after the procedure. Transvenous approaches were used to deploy a pre-mounted, balloon-expandable metallic stent in all cases. ResultsOf 15 dogs, all had annular hypoplasia, and in addition, supravalvular stenosis was diagnosed in 11 of 15 dogs, and three had R2A coronary malformation. All dogs survived to discharge. One dog died less than four weeks postoperatively (non-cardiac), but 14 of 15 dogs were re-examined at four weeks. Severity reduced in all cases; median pressure gradient reduced from 137 mmHg (range 81–202 mmHg) to 83 mmHg (range 31–155 mmHg). Clinical signs improved in all cases, and hematocrit reduced in all dogs with erythrocytosis. The median follow-up time was 280 days (range 95–896 days). Over one-year follow-up was available in six of fifteen dogs. Two dogs died because of refractory right-sided congestive heart failure signs: one at 10 months and one at 22 months postoperatively. ConclusionsTransvalvular pulmonic stent angioplasty technique was associated with an improvement in clinical signs and reduction in stenosis severity for all dogs in this population, including cases with supravalvular PS or circumpulmonary coronary malformation.

Bronchial stenting in infants with severe bronchomalacia: Technique and outcomes

ObjectivesTo report the first use of a balloon expandable bare metal stent for treating infant bronchomalacia. BackgroundInfant bronchomalacia often requires prolonged mechanical ventilation and can be life-threatening. Effective treatment for severe infant bronchomalacia continues to be elusive. We present three cases of bronchial stenting for no-option or treatment refractory infant bronchomalacia. MethodsThree consecutive cases of stenting to relieve conservative treatment refractory severe infant bronchomalacia were performed between February 2019 and December 2020. Initial diagnosis was confirmed with Computed Tomography (CT) angiography. Patients underwent rigid micro laryngoscopy, bronchoscopy, and flexible bronchoscopy to evaluate the airway. Initial conservative management strategies were pursued. Patients failing initial conservative management strategies were considered for rescue bronchial stenting. ResultsOur initial clinical experience with a coronary bare metal stent for these procedures has been favorable. The stent was easy to deploy with precision. We did not encounter stent embolization or migration. There was sufficient stent radial strength to relieve bronchomalacia without causing restenosis or erosion. There was no significant granulation tissue formation. In one patient, the stent was removed after 12 months of somatic growth; this was uneventful and bronchial patency was maintained. There were no complications in any of our patients regarding stent placement and reliability. ConclusionIn cases of three infants with severe bronchomalacia, we found that bronchial stenting with the bare metal coronary stent was effective in relieving bronchial stenosis.

Technical Feasibility and Histological Analysis of Balloon-Expandable Metallic Stent Placement in a Porcine Eustachian Tube

There is a clinical need to develop a stent to treat obstructive and refractory Eustachian tube dysfunction (ETD) after balloon Eustachian tuboplasty. An animal model for stent placement in the Eustachian tube (ET) is needed to develop optimal designs and materials, as stents for ETD have not been clinically applied. The purpose of this study was to evaluate the technical feasibility of stent placement and histological changes in a porcine ET model. Six ETs were evaluated in three pigs. Cobalt–chrome alloy stents with two different diameters were placed in the left and right ET of each animal (right, 3.5 mm; left, 2.5 mm). The outcomes were assessed by endoscopic and fluoroscopic imaging during the procedure, computed tomography after the procedure, and by histological examinations. Stent placement was technically successful in all specimens after metallic guiding sheaths were located in the nasopharyngeal end of the ET. The mean luminal diameters of the proximal, middle, and distal portions of the larger stents in the right ETs were 3.48 mm, 2.54 mm, and 2.15 mm, respectively. In the left ETs using smaller stents, these values were 2.49 mm, 1.73 mm, and 1.42 mm, respectively. The diameters of the inserted stents differed by stent location and the original diameter. Histological findings showed tissue hyperplasia with severe inflammatory cell infiltration at 4 weeks after stent placement. In conclusion, stent placement into the porcine ET was technically feasible, and stent-induced tissue hyperplasia was significantly evident. The luminal configuration of the placed ET stent changed according to its non-elastic nature and anatomical features of the porcine ET. Using this model, ET stents of various materials and designs with anti-inflammatory or anti-proliferative drugs can be optimized for future treatments of ET dysfunction.

Long-term management and outcomes of tracheobronchial stent by flexible bronchoscopy in infants

Tracheobronchial (TB) lumen narrowing may require prolonged positive-pressure ventilation, endotracheal tube intubation or even surgical interventions. Therapeutic flexible bronchoscopy (TFB) of balloon-expandable metallic stent (BEMS) placement and subsequent forceps, laser and balloon dilatation management might be less invasive and helpful. This study aimed to analyse the placement, follow-up management with TFB and long-term outcomes in small infants with BEMS. This retrospective study reviewed the medical records and associated TFB videos of infants with a maximum body weight (BW) of 5.0 kg who had TB BEMS placement from January 2005 to December 2017 at our institution. All TFB procedures were supported with a novel noninvasive ventilation, nasopharyngeal oxygen with intermittent nose closure and abdominal compression. Forty-one BEMSs were placed in 24 infants. The mean BW and mean age were 4.0 ± 0.7 kg and 4.9 ± 2.4 months, respectively. There were 20, 8 and 13 stents located in trachea, carina and main-stem bronchi, respectively. Seven infants with 13 stents died without obvious stent-related mortality. Seven stents in five infants were successfully retrieved by rigid endoscopy (RE). At placement, the diameters of 28 tracheal and 21 bronchial stents were 7.5 ± 1.1 (4-10) and 5.4 ± 0.9 (4-8) mm, respectively. These implanted BEMSs could be gradually and significantly (p < 0.01) expanded. At the end of the follow-up period, all the remaining 21 stents in 12 infants were functional. The diameters of the 14 remaining tracheal and 13 remaining bronchial stents were 9.6 ± 2.0 (8-14) and 7.2 ± 1.4 (4-10) mm, respectively. BEMSs are practical and effective in selected small infants with benign TB narrowing and can be safely implanted and managed with TFB, and finally retrieved by RE.

Adjustable diameter TIPS in the pediatric patient: the constrained technique.

Placement of transjugular intrahepatic portosystemic shunt (TIPS) is necessary in children with portal hypertension complicated by variceal bleeding or ascites. However, placement of adult-sized endografts may be problematic due to the smaller anatomy of pediatric patients. On the other hand, placement of fixed diameter smaller stents have the corresponding problem of not accommodating future growth of the child. We describe a novel method to create an adjustable diameter TIPS as a technical solution to these problems. In this technique, a balloon expandable bare metal stent is placed concentrically around the ePTFE TIPS endograft, creating an intentional narrowing in the shunt diameter than can be expanded with balloon dilation at future procedures as needed. This allows for optimal calibration of shunt hemodynamics according to the child's growth and prevents the potential need for placement of additional shunts or technically challenging TIPS reduction procedures.

Flexible endoscopy for pediatric tracheobronchial metallic stent placement, maintenance and long-term outcomes.

ObjectivesTo assess the placement, surveillance management and long-term outcomes of the tracheobronchial (TB) balloon expandable metallic stent (BEMS) managed by therapeutic flexible endoscopy (TFE).MethodsThis is a retrospective review and analysis of all computerized medical records and related flexible endoscopy videos of pediatric patients who received TB BEMS during 20 years period, from January 1997 to December 2016. TFE techniques with forceps debridement, balloon dilatation and laser ablation were used to implant stents, perform regular surveillance, maintain their functions, and expand the diameters of BEMS. Short-length (30cm-36cm) endoscopes of OD 3.2mm to 5.0mm coupled with the noninvasive ventilation, without ventilation bag, mask or airway tube, supported the whole procedures.Results146 BEMS were implanted in 87 consecutive children, including 84 tracheal, 15 carinal and 47 bronchial stents. At the time of placement, the mean age was 35.6 ± 54.6 month-old (range 0.3–228) and the mean body weight was 13.9 ± 10.6 kg (range 2.2–60). Surveillance period was 9.4 ± 6.7 years (range, 0.3–18.0). Satisfactory clinical improvements were noted immediately in all but two patients. Seventy-two (82.8%) patients were still alive with stable respiratory status, except two patients necessitating TFE management every two months. Fifty-one stents, including 35 tracheal and 16 bronchial ones, were successfully retrieved mainly with rigid endoscopy. Implanted stents could be significantly (< .001) further expanded for growing TB lumens. The final stent diameters were positively correlated to the implanted duration. Altogether, 33 stents expired (15 patients), 51 were retrieved (40 patients), and 62 remained and functioning well (38 patients), with their mean duration of 7.4 ± 9.5, 34.9 ± 36.3 and 82.3 ± 62.5 months, respectively.ConclusionIn pediatric patients, TFE with short-length scopes coupled with this NIV support has provided a safe, feasible and effective modality in placing and subsequently managing TB BEMS with acceptable long-term outcomes.

Management of tracheobronchial obstruction in infants using metallic stents: long-term outcome.

Tracheobronchial obstruction, although uncommon in the pediatric age group, remains a challenging problem. We review the long-term outcome of endoscopic metallic stenting in infants with tracheobronchial obstruction. Medical records of all pediatric surgical patients who underwent tracheobronchial metallic stenting in our center were reviewed retrospectively from 1996 to 2014. Patients' demographic data, including etiology, associated anomalies and nature of obstruction were reviewed. Outcome measures include complications such as re-stenosis, granulation tissue, stent migration, fractured stent, maximal tracheal diameter achieved, weaning of ventilator and growth at interval follow-up. Twelve balloon-expandable metallic stents were placed in the trachea (n = 10) and/or bronchi (n = 2) of 5 patients with a median age of 13 months (range 5-30 months). Etiology of the airway obstruction included congenital tracheal stenosis (n = 4), giant cervical and superior mediastinal lymphatic malformation with tracheobronchomalacia (n = 1). Seven complications were reported (3 patients developed granulation tissue, 2 patients had re-stenosis, 1 stent migrated, 1 stent fractured). All patients survived and were in good condition with a median follow-up of 16 years (range 11-18 years). Three patients weaned off ventilator and oxygen. Endoscopic stenting with metallic stent has satisfactory long-term outcome in treating infants with tracheobronchial obstruction.

Management of embedded metallic stents used in the treatment of grades III and IV subglottic, and upper tracheal stenosis in adults.

The aim of this study was to evaluate the post-operative complications of using balloon-expandable metallic stents in treatment of benign, major subglottic and tracheal stenosis in adult patients whom conventional therapy has failed and to demonstrate how to deal with these complications in the long run. A retrospective review of five cases; adlut patiets with benign, major subglottic and upper tracheal stenosis whom were treated with balloon expandable metallic stents at King Abdulaziz University Hospital, in the years between 2008 and 2013. Granulation tissue formed in five of the four cases and restenosis occurred. Other complications encountered were stent infection and dislodgment. The complications were managed by removing the stents surgically via a laryngofissure incision and required the placement of a Montgomery T-tube. Managing the restenosis due to granulation tissue formation around the metallic stents is best achieved by removing the embedded metallic stents surgically via open technique and then by placement of a Montgomery T-tube as a bridging option to successful decannulation. Open surgical procedures remain the mainstay treatment for advanced airway stenosis.

Stent outcomes for infrapopliteal arterial occlusive disease

This study aimed to determine if the different stent types used in the treatment of infrapopliteal arterial occlusive disease provide any significant advantage over one another at 6 and 12-month follow-up. Consecutive patients undergoing stenting of infrapopliteal lesions were enrolled into a non-randomised prospective registry and followed-up for 1 year. Outcome measures included binary restenosis, target lesion revascularisation, major amputation, and change in Rutherford-Becker score and ankle-brachial index (ABI).Thirty-three patients were enrolled including four patients with bilateral disease. There were 20 target vessels in the drug-eluting stent (DES) group, 13 target vessels in the balloon-expandable bare metal stent (BE-BMS) group and 14 target vessels in the self expandableb are metal stent (SE-BMS) group. Most of the patients in the study were octogenarians except in the SE-BMS group where the mean age was 73 ± 9 years. At 12 months, seven patients had died (DES = 6, BE-BMS = 1) from cardiac and cancer-related diseases. In-stent and peri-stent binary restenosis were non-statistically different between all three groups. There was a nonstatistically significant trend towards higher target vessel revascularisation in the BE-BMS group. Survival curves in all stent types demonstrated restenosis to occur within the first 6 months post-procedure. There was no significant difference in the change in Rutherford-Becker score or ABI between the groups. No major limb amputations occurred during the 12-month period. In conclusion,we did not detect a significant difference in stent performance between the different stent types used to treat infrapopliteal arterial occlusive disease. The choice of stent did not seem to affect patient survival or major amputation-free survival at 1-year follow-up.

Long-term outcomes of congenital tracheal stenosis treated by metallic airway stenting

AimCongenital tracheal stenosis is an obstructive airway lesion that often presents as a life-threatening emergency. We had introduced the balloon dilatation and placement of the expandable metallic airway stent as a therapeutic option, and this study aimed to clarify the long-term outcomes in pediatric patients. MethodsA retrospective review of five infants in whom balloon expandable metallic airway stents (10–40mm long and 6–8mm in diameter) were inserted in 1997 to 2000 was conducted. ResultsThere was an immediate improvement of respiratory obstruction in all five infants (aged 7days to 12months) with four weaned from ventilation. One child died after 9months of palliative treatment. In all inflammation and granulation tissue developed over the stents, but this could be managed by scraping or balloon compression. Metallic stents have been in place a mean of 12years (range 6months to 13years) after insertion without other complications. Four children are alive and well with their stents in place. Recently, an attempt to remove the stent was done in two patients who showed dyspnea on exertion. They underwent tracheoplasty following successful complete removal of metallic stent using cardiopulmonary bypass. ConclusionUse of expandable metallic airway stents following balloon dilatation can be left for long periods to relieve tracheal obstruction. Development of granulation tissue is a major treatable complication. Removal of the stent was safely completed by open surgical intervention using a cardiopulmonary bypass. The airway stent may provide an important therapeutic option in selected cases with congenital tracheal stenosis.

Treatment of congenital tracheal stenosis by balloon-expandable metallic stents in paediatric intensive care unit

The aim of this study was to evaluate the use of balloon-expandable metallic stents in the treatment of children with congenital tracheal stenosis in whom conventional therapy has failed. From 2010 to 2011, balloon-expandable metallic stents were implanted into the trachea of eight infants aged 2-20 months in the paediatric intensive care unit. The infants had severe airway obstruction caused by congenital tracheal stenosis. Tracheal stents were placed after intraluminal balloon dilatation of the tracheal stenosis, inserted with balloon catheters and implanted into the desired position bronchoscopically. The stents were 12 to 29 mm long and 4 mm in diameter. Seven children were relieved of airway obstruction after this procedure. However, a child died due to severe sepsis after the placement of bronchial stents. No granulation tissue developed over the stents in any of the children. Stents have been in place for 1-6 months after insertion without any other complication. Balloon-expandable metallic stents are effective in relieving airway obstruction by congenital tracheal stenosis in children. This technique may provide an important remedy for congenital tracheal stenosis in children.

Percutaneous Coronary Intervention for ST-elevation Myocardial Infarction: Drug-Eluting Stents or Bare Metal Stents?

The treatment paradigm for patients with an ST-elevation myocardial infarction (STEMI) has shifted greatly in the last 20 years. The use of fibrinolytic agents vastly altered the landscape in treating this entity and was further advanced by the introduction of percutaneous catheter-based methods of therapy. Percutaneous coronary intervention (PCI) has become the preferred method of treatment for patients with this condition when compared with thrombolytic agents as evidenced by a number of positive clinical trials. However, PCI in itself has had several adaptations over the last decade, namely in the shift from a balloon-only approach to the widespread usage of balloon-expandable metallic stents. The use of bare metal stents has proven to be more efficacious in regard to rates of repeat procedures when compared with the balloon-only approach and has become a standard in PCI for STEMI. The composition of the stents themselves had also undergone transformation as evidenced by the introduction of drug-eluting stents (DES). Although there have been encouraging data to support the use of DES in the elective setting, the use of these devices in primary PCI has been controversial. The pathologic milieu that is present in the STEMI setting is distinctly different than that seen in the elective, stable atherosclerotic setting and the use of DES has raised concerns over safety issues with their implementation. There have been a host of recent studies dedicated to elucidating the risk of using DES versus bare metal stents in the setting of STEMI and although the results have been generally favorable for the use of DES, this subject remains one that is under significant scrutiny.

Incidence, Anatomical Location, and Clinical Significance of Compressions and Fractures in Infrapopliteal Balloon-Expandable Metal Stents

To investigate the incidence, anatomical location, and clinical impact of fractures and/or compression of infrapopliteal balloon-expandable metal stents implanted for critical limb ischemia (CLI) treatment. This prospective study included 63 CLI patients (45 men; mean age 71.3+/-9.5 years) who had been treated with infrapopliteal angioplasty and stent placement for 191 lesions in 84 limbs. In all, 369 stents (296 stainless steel and 73 cobalt-chromium alloy) were implanted; 239 were placed overlapping in tandem lesions. Mean length of the overall stented segment was 4.4+/-6.3 cm (range 1.6-14.0). Stents were located in the tibioperoneal (n = 34), anterior tibial (n = 195), posterior tibial (n = 63), and peroneal (n = 77) arteries. Follow-up consisted of digital subtraction angiography and infrapopliteal radiography imaging at 2 different angles. Evaluation of stents for the presence of fracture and/or compression was done after digital processing at the highest possible magnification. Stent fractures were defined according to published standards, whereas compression was classified as severe shape alteration and/or collapse of the stent mesh. Angiographic restenosis was based on a 50% threshold. Mean follow-up was 15+/-11 months (range 6-60). Image analysis detected 1 (0.3%) severe stent fracture (complete separation and misalignment of stent struts) and 11 (3.0%) stent compressions. Infrapopliteal stent fracture and compressions were associated with increased artery restenosis [100% (12/12) versus 47.3% (169/357), p<0.001] and an increased rate of clinical deterioration and clinically-driven reinterventions [41.7% (5/12 limbs) versus 19.4% (14/72 limbs), p = 0.04]. The single fracture and most of the compressions were located in the distal third of the anterior tibial artery. Stent fractures and compressions of infrapopliteal balloon-expandable metal stents are infrequent. However, they may be related to increased restenosis.

Use of a balloon-expandable metallic stent to relieve malignant urethral obstruction in a cat

A 19-year-old neutered male domestic shorthair cat was evaluated because of signs of urinary tract obstruction. Physical examination findings were consistent with urethral obstruction, and a mass could be palpated in the region of the bladder neck. Abdominal ultrasonography and thoracic radiography revealed a mass in the trigone of the urinary bladder and a solitary mass in the left caudal lung lobe. Cytologic examination of the urine sediment, samples obtained by means of traumatic urethral catheterization, and fine-needle aspirates of the bladder mass did not result in a diagnosis. A balloon-expandable metallic stent was placed in the proximal portion of the urethra to relieve the malignant obstruction. After stent placement, the cat had signs of urinary incontinence and detrusor atony, both of which resolved with medical treatment. The cat was euthanized 1 month after stent placement because of progressive azotemia. Histologic examination of necropsy samples revealed grade III urothelial carcinoma and papillary pulmonary adenocarcinoma. Findings suggested that stent placement may be a viable palliative treatment in cats with malignant urinary obstruction.

Percutaneous portal venoplasty and stenting for anastomotic stenosis after liver transplantation

To review percutaneous transhepatic portal venoplasty and stenting (PTPVS) for portal vein anastomotic stenosis (PVAS) after liver transplantation (LT). From April 2004 to June 2008, 16 of 18 consecutive patients (11 male and 5 female; aged 17-66 years, mean age 40.4 years) underwent PTPVS for PVAS. PVAS occurred 2-10 mo after LT (mean 5.0 mo). Three asymptomatic patients were detected on routine screening color Doppler ultrasonography (CDUS). Fifteen patients who also had typical clinical signs of portal hypertension (PHT) were identified by contrast-enhanced computerized tomography (CT) or magnetic resonance imaging. All procedures were performed under local anesthesia. If there was a PVAS < 75%, the portal pressure was measured. Portal venoplasty was performed with an undersized balloon and slowly inflated. All stents were deployed immediately following the predilation. Follow-ups, including clinical course, stenosis recurrence and stent patency which were evaluated by CDUS and CT, were performed. Technical success was achieved in all patients. No procedure-related complications occurred. Liver function was normalized gradually and the symptoms of PHT also improved following PTPVS. In 2 of 3 asymptomatic patients, portal venoplasty and stenting were not performed because of pressure gradients < 5 mmHg. They were observed with periodic CDUS or CT. PTPVS was performed in 16 patients. In 2 patients, the mean pressure gradients decreased from 15.5 mmHg to 3.0 mmHg. In the remaining 14 patients, a pressure gradient was not obtained because of > 75% stenosis and typical clinical signs of PHT. In a 51-year-old woman, who suffered from massive ascites and severe bilateral lower limb edema after secondary LT, PVAS complicated hepatic vein stenosis and inferior vena cava (IVC) stenosis. Before PTPVS, a self-expandable and a balloon-expandable metallic stent were deployed in the IVC and right hepatic vein respectively. The ascites and edema resolved gradually after treatment. The portosystemic collateral vessels resulting from PHT were visualized in 14 patients. Gastroesophageal varices became invisible on poststenting portography in 9 patients. In a 28-year-old man with hepatic encephalopathy, a pre-existing meso-caval shunt was detected due to visualization of IVC on portography. After stenting, contrast agents flowed mainly into IVC via the shunt and little flowed into the portal vein. A covered stent was deployed into the superior mesenteric vein to occlude the shunt. Portal hepatopetal flow was restored and the IVC became invisible. The patient recovered from hepatic encephalopathy. A balloon-expandable Palmaz stent was deployed into hepatic artery for anastomotic stenosis before PTPVS. Percutaneous transhepatic internal-external biliary drainage was performed in 2 patients with obstructive jaundice. Portal venous patency was maintained for 3.3-56.6 mo (mean 33.0 mo) and all patients remained asymptomatic. With technical refinements, early detection and prompt treatment of complications, and advances in immunotherapy, excellent results can be achieved in LT.

Use of a balloon-expandable metallic stent for treatment of nasopharyngeal stenosis in dogs and cats: six cases (2005–2007)

To determine outcome associated with use of a balloon-expandable metallic stent for treatment of nasopharyngeal stenosis in dogs and cats. Retrospective case series. 3 dogs and 3 cats. All 6 animals had severe inspiratory stertor at initial examination. Two animals had no orifice present at the stenosis. Nasopharyngeal stenosis was diagnosed and stent size determined by use of computed tomography. A percutaneous transluminal angioplasty balloon premounted with a balloon-expandable metallic stent was placed over a guidewire, advanced through the stenotic lesion under fluoroscopic and rhinoscopic guidance, and dilated to restore patency. All animals had immediate resolution of clinical signs after stent placement. The procedure took a median of 38 minutes (range, 22 to 70 minutes). One animal with a stenosis located far caudally needed the tip of the stent resected because of hairball entrapment and exaggerated swallowing. Both animals without an orifice in the stenosis had tissue in-growth requiring a covered stent. All animals were reexamined 6 to 12 weeks after treatment via rhinoscopy, radiography, computed tomography, or a combination of techniques. All animals lacked signs of discomfort; 5 of 6 were breathing normally 12 to 28 months after the procedure. Transnasal balloon-expandable metallic stent placement may represent a rapid, safe, noninvasive, and effective treatment in animals with nasopharyngeal stenosis. If the stenosis is extremely caudal in the nasopharynx, serial balloon dilatation might be considered prior to stent placement. A covered stent should be considered initially if the stenosis is completely closed.

The role of airway stenting in pediatric tracheobronchial obstruction☆

Tracheobronchial obstruction is infrequent in the pediatric age group but it is associated with significant morbidity and mortality. The purpose of this study is to review the results of a single institution experience with endoscopic stent placement in children with benign tracheobronchial obstruction, and with special concern on safety and clinical effectiveness. Twenty-one patients with severe airway stenosing disease in which stent placement was performed between 1993 and 2006. Inclusion criteria according to the clinical status were: failure to wean from ventilation, episode of apnea, frequent respiratory infections (>3 pneumonia/year), and severe respiratory distress. Additional criteria for stent placement were: failure of surgical treatment, bronchomalacia, and tracheomalacia refractory to previous tracheostomy. Selection of the type of stent depended on the site of the lesion, the patient's age, and the stent availability when time of presentation. The following variables were retrospectively evaluated: age, type of obstruction, associated malformations, stent properties, technical and clinical success, complications and related reinterventions, outcome and follow-up period. Thirty-three stents were placed in the trachea (n=18) and/or bronchi (n=15) of 21 patients with a median age of 6 months (range, 9 days-19 years). Etiology of the airway obstruction included severe tracheomalacia and/or bronchomalacia in 19 cases (90%), and postoperative tracheal stenosis in two. Twelve children had a total of 20 balloon-expandable metallic stents placed, and 10 had 13 silicone-type stents (one patient had both). In nine patients (42%) more than one device was placed. Stent positioning was technically successful in all but one patient. Clinical improvement was observed in 18 patients (85%) but complications occurred in five of them (27%). Eight patients died during follow-up but only in one case it was related to airway stenting. Thirteen patients (62%) are alive and in good condition with a mean follow-up of 39 months (1-13.8 years). Although the results were based on a small series, placement of stents in the pediatric airway to treat tracheobronchial obstruction seems to be safe and effective. Stenting is a satisfactory therapeutic option when other procedures have failed or are not indicated.

Use of balloon‐expandable metallic stent in a premature infant with congenital tracheobronchial stenosis

A congenital tracheobronchial stenosis is a rare obstructive lesion of the airway characterized by intrinsic narrowing of a segment of the trachea and bronchi. In this report, we present the smallest premature infant with a congenital tracheobronchial stenosis who has been successfully treated with balloon dilatation and placement of a balloon-expandable metallic stent.