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Vascular and Interventional Radiology |
1 From the Departments of Diagnostic Radiology (H.Y.S., D.H.L.), Internal Medicine (H.Y.J., S.B.K., Y.I.M.), Thoracic and Cardiovascular Surgery (S.I.P.), and Biomedical Engineering (S.G.K.), Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap-Dong, Songpa-Ku, Seoul 138-736, Korea. Received November 8, 1999; revision requested December 10; revision received February 15, 2000; accepted February 23. Supported by a grant (HMP-98-G-2-043) of the Highly Advanced National Project, Ministry of Health and Welfare, Republic of Korea. Address correspondence to H.Y.S. (e-mail: hysong@www.amc.seoul.kr).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Under fluoroscopic guidance, covered retrievable expandable nitinol stents were placed in 25 patients with a benign esophageal stricture and were removed with a retrieval hook 1–8 weeks later.
RESULTS: Stent placement was successful in all patients, with no procedural complications. After stent placement, all patients could ingest solid food. The stents were successfully removed from all but two patients. One patient passed the stent via the rectum, and the other regurgitated a high cervical stent. After stent removal, one patient developed a small esophagobronchial fistula, which spontaneously sealed within 1 week of stent removal. After stent removal or migration, all patients could ingest solid food. During follow-up (mean, 13 months; range, 2–25 months) after stent removal or migration, 12 patients maintained their improvement in dysphagia and needed no further treatment. Thirteen patients with recurrence were treated by means of repeat balloon dilation.
CONCLUSION: Use of retrievable expandable nitinol stents seems to be a safe and effective method of treatment in selected patients with benign esophageal strictures.
Index terms: Esophagus, grafts and prostheses, 71.1269, 71.744 • Esophagus, interventional procedure, 71.1269 • Esophagus, stenosis or obstruction, 71.744
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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To overcome these problems, a polyurethane-covered retrievable expandable Z stent was recently devised to be used temporarily in patients with a benign stricture (19). The retrievable Z stent, however, continues to be plagued by stent migration; the authors of one article (19) referred to only a small number of patients (five patients with a benign esophageal stricture) with limited follow-up. To overcome the problems of the retrievable Z stent, two types of retrievable stents with a nitinol wire were designed. The purpose of this study was to investigate the safety and clinical effectiveness of the covered retrievable expandable nitinol stent in 25 patients with a benign esophageal stricture.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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To make the stent removable, a drawstring of nylon monofilament was attached to its upper inner margin (Fig 2). A 2-mm-diameter nylon loop was hooked inside each bend of the upper end of the stent and secured with sutures. Another nylon thread was passed through each of the nylon loops to form a larger loop (drawstring) that filled the circumference of the inside of the proximal stent. The resultant loop was then tied.
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In nine of the patients, balloon dilation was not effective because of a tight stenosis in which dilation to 10 mm was not feasible. In patients with tight stenoses, balloon dilation was performed by using a 10-mm high-pressure balloon catheter (Medi-tech/Boston Scientific, Watertown, Mass). The balloon was inflated by injecting it with diluted water-soluble contrast medium (Ultravist 300; Schering, Ansung, Korea) to 12 atm (1,216 kPa) for 3 minutes. These inflations were repeated three times on the same day. The dilation procedure was repeated 3–5 days after the first balloon dilation session. In the nine patients with tight stenoses, the hourglass deformity created by the stric-ture did not disappear from the balloon contour. In the other 16 patients, balloon dilation of the stricture to 15 or 20 mm was possible, but it did not work effectively because of frequent recurrences within 2 weeks of dilation.
The interval between ingestion of a corrosive agent in patients with a corrosive stricture or the onset of dysphagia in patients with radiation fibrosis, sclerotherapy, or reflux esophagitis and stent placement was 1–720 months (mean, 128 months).
Diagnosis was established by reviewing the patient’s history and findings at esophagography, computed tomography, and endoscopic biopsy. One patient who underwent radiation therapy after esophagectomy with esophagogastrostomy for esophageal cancer was considered to have radiation fibrosis because of negative biopsy results and because there was no evidence of recurrence at 46-month follow-up. The strictures were located in the cervical esophagus in two patients, upper thoracic esophagus in two, middle thoracic esophagus in five, lower thoracic esophagus in 13, entire thoracic esophagus in two, and esophagocolonostomy site in one.
Informed consent was obtained from each patient, and this pilot study was approved by our university committee on human investigation.
Techniques of Stent Placement and Removal
The site, severity, and length of the stricture were evaluated by means of barium esophagography prior to stent placement. An aerosol spray for topical anesthesia of the pharynx and drugs for sedation were routinely administered before the procedure. The patient was asked to swallow a small amount (approximately 10 mL) of the water-soluble contrast medium for opacification of the narrowed esophageal lumen. Then, the location of the narrowed esophageal lumen was marked on the patient’s skin under fluoroscopic guidance. A 0.035-inch exchange guide wire (Radiofocus M; Terumo, Tokyo, Japan) was inserted through the mouth across the stricture into the distal portion of the esophagus or stomach. A 5-F graduated catheter (Cook, Bloomington, Ind) was passed over the guide wire as far as the distal portion of the stricture to measure the length of the stricture. Type A stents were placed by using a 9-mm introducer system (Sten-tech, Seoul, Korea), and type B stents were placed by using a 7-mm introducer system (Sten-tech) under fluoroscopic guidance according to a previously reported technique (1). When the type A stents were placed, ice water was used to collapse the stent into the introducer sheath.
We removed the stent from the patients if a complication such as severe pain or formation of new strictures occurred. In patients who experienced no complications, we routinely removed the stent 8 weeks after placement. The stent was removed under fluoroscopic guidance by using a 15-F retrieval set (Sten-tech) according to the same technique reported previously (19). Esophagography was performed immediately after stent removal.
Follow-up
All patients underwent esophagography 1–3 days after stent placement to verify the degree of expansion and the position and patency of the stent. When esophagography revealed incomplete expansion of the stent, radiography was performed every 2–3 days until the stent expanded fully. After stent placement, patients were fed a liquid diet for 1–3 days until esophagography was performed. Patients were not allowed a solid diet until the follow-up esophagogram showed full expansion of the stent. All patients were advised to sit upright when eating, to drink carbonated drinks during and after meals to clean food debris from their stent, and to chew their food thoroughly.
Clinical examination and esophagography were performed for evaluation of stent patency every 2 weeks after the first esophagogram until the stent was removed. Clinical examinations and follow-up esophagography were performed at 1, 6, and 12 months after stent removal to assess possible recurrence. After this time, patients were advised to visit the outpatient clinic if symptoms recurred. All patients were contacted by telephone every 6 months to obtain information concerning food intake, dysphagia, and coughing.
Interpretation of the Results
To assess clinical improvement, food intake capacity before and after treatment was categorized in four ways: aphagia, ability to ingest liquids, ability to eat soft foods, and ability to eat solid foods. At presentation, 17 patients were able to ingest only liquids, and the remaining eight patients were able to eat soft foods, with limitation.
The initial and/or maintained improvement rates after stent removal were analyzed. Initial improvement occurred when follow-up esophagograms obtained immediately after stent removal showed that the stricture was dilated to at least twice the width of the initial stricture so that the patient could ingest solid foods without dysphagia. Maintained improvement was defined as no recurrence of clinical dysphagia and no recurrence of the stricture depicted on follow-up esophagograms obtained 1, 6, and 12 months after stent removal. The duration of 1, 6, or 12 months was each considered as a period for maintaining improvement.
The cumulative improvement rates after stent removal were evaluated by using a Kaplan-Meier analysis. To determine whether the duration of symptoms before stent placement and the duration of stent placement made any difference in the improvement rates, we classified the patients into a group with recurrence and a group without recurrence. We compared the mean symptom duration before stent placement, duration of stent placement, and length of the stricture in these two groups by using the Mann-Whitney U test. We also evaluated the influence of the severity of stricture (tight vs soft), cause of the stricture (acetic acid vs lye), and type of stent (type A vs type B) in the recurrence of the stricture after stent removal by using the 
2 test. Finally, we analyzed the influence of the duration of symptoms, duration of stent placement, and length of the stricture in the cumulative improvement rate.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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No procedural complications occurred in any of these patients. In five patients, the stent was removed because of severe pain 1–4 weeks after stent placement. The pain subsided immediately after removal of the stent. New strictures developed in 12 patients 2–6 weeks (mean, 4 weeks) after stent placement. The new strictures developed just above and/or below the stent owing to hypertrophy. In the first two patients who experienced formation of new strictures, the stent was electively removed 8 weeks after placement. In these two patients, the new stricture progressed until stent removal. On the basis of this experience, we decided to remove the stents from the other 10 patients when a stricture was detected on follow-up esophagograms (Fig 3).
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Stent Removal
Stents were removed from all but two patients in whom the stent was passed through the rectum or vomited. In five patients with no complications, the stent was electively removed at 8 weeks. In the other 18 patients, the stent was removed 1–8 weeks (mean, 3 weeks) after placement because of complications (five patients with severe pain, 12 with formation of new strictures above and/or below the stent, and one with stent migration). In eight of the 23 patients whose stents were removed, the stents were blood stained, but no patient bled during and/or after stent removal. In two of 12 patients in whom new strictures formed, we first dilated the stricture above the stent with a 20-mm-diameter 3-cm-long esophageal balloon catheter (Medi-tech/Boston Scientific) and then removed the stent. In the other patients with new strictures, we did not dilate the new strictures because they were mild. The new strictures above or below the stent did not cause dysphagia and were fairly responsive to balloon dilation.
Stent removal was well tolerated in all but one patient. In this patient, the nylon thread became untied during stent removal. To remove the stent, a 0.035-inch guide wire (Radiofocus M; Terumo) was introduced through the mouth and across the stent into the distal esophagus. A sheath with a dilator was passed over the guide wire into the distal stent lumen. After the guide wire and dilator were removed from the sheath, a hook wire was introduced into the sheath and advanced until the hook passed through the sheath into the lumen of the tail of the stent. Then, the hook was pulled out of the tail of the stent so that it hooked onto the distal collar. When this occurred, the hook and sheath were pulled out of the esophagus. The stent was retrieved with eversion. One patient had a small esophagobronchial fistula after removal of the stent. This fistula sealed spontaneously within a week (Fig 4).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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In the second group, the procedure was considered in patients in the late chronic stage of corrosive stricture or in patients with severe radiation fibrosis whose esophageal stenosis was so tight that dilation of the stricture to 10 mm was difficult or impossible. In those patients, the expandable stent was able to dilate the stricture to as much as the diameter of the stent because the placed stent tended to exert an expansile force until it reached the preset expanded diameter. Previous study findings (20) showed that the esophageal rupture rate of balloon dilation in 19 patients in the chronic stage of corrosive stricture is 32%. In five (26%) of these 19 patients, dilation of the stricture to 10 mm was extremely difficult or impossible because the stricture was too tight. In eight patients with tight corrosive strictures and in one patient with radiation fibrosis in our series, these two problems were overcome by using a retrievable expandable stent.
Interestingly, all three patients with noncorrosive strictures who underwent stent placement (one patient with stent placement for 4 weeks, one for 5 weeks, and one for 8 weeks) experienced improvement of their strictures with no recurrence. The patient whose stent was in place for 7 weeks had undergone a subtotal gastrectomy with Roux-en-Y gastrojejunostomy for marginal ulcer bleeding 3 months prior to stent placement. The patient whose stent was in place for 5 weeks had undergone sclerotherapy for esophageal varix 2 months before stent placement. In these two patients, the strictures could be dilated to 20 mm before stent placement, but they experienced frequent recurrence. After stent placement, the strictures healed without recurrence. However, the patients with reflux esophagitis or corrosive strictures will require follow-up for the development of premalignant or malignant complications of their underling disease.
We agree that an esophageal stent should remain in place until the stricture heals (19). In the case of benign strictures, 4–8 weeks was suggested as the optimal time for removal of a placed stent because formation of new strictures and recurrence of strictures rarely occurred within that period (18). In our series, however, formation of new strictures developed in 12 of the 25 patients with benign strictures 2–6 weeks after stent placement. In addition, stricture recurred in three of seven patients with benign strictures in whom the stent was removed 8 weeks after placement. Nine (90%) of 10 patients with corrosive strictures in whom the duration of symptoms was less than 7 months experienced recurrence of stricture, whereas only four (33%) of 12 patients in whom the duration of symptoms was 7 months or longer experienced recurrence. In patients who were in the late chronic stage of corrosive stricture and in those with noncorrosive strictures, removal of the stent even 2–5 weeks after placement seemed to be acceptable; however, for patients in the early chronic stage of corrosive stricture, even 8 weeks seems to be too soon. Therefore, we believe that the optimal time for stent removal is still undetermined.
We surmise that the degree of hypertrophy above or below the stent depends on the cause of the stricture, its severity, and the duration of symptoms. Cwikiel et al (2) reported a rate of 2% for the formation of new strictures in 100 patients who underwent stent placement for malignant esophageal strictures. This rate is less than the rate in patients who undergo stent placement for benign esophageal strictures. We agree that formation of a new stricture eventually causes recurrence of dysphagia and necessitates further treatment unless the stent is removed (18). In all patients with new strictures, the new stricture improved during follow-up after stent removal, and the new stricture responded to balloon dilation following stent removal. In patients who undergo stent placement for benign esophageal strictures, it is now our policy to remove the stent at the time of stricture formation. To detect a new stricture, follow-up esophagography or endoscopy every 2 weeks is required.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
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