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Esophageal and upper GI stenting
Esophageal and Upper GI Stenting Mark G. Cowling, MRCP, FRCR, Robert C. Mason, MS, FRCS, and Andreas N. Adam, FRCP, FRCR
Self-expanding metallic stents are now well established in the palliative management of inoperable esophageal carcinoma. Dysphagia is successfully palliated in more than 90% of patients treated, with a low incidence of procedural complications. Use of covered stents minimizes recurrent dysphagia due to tumor ingrowth, and also provides palliation for the vast majority of malignant esophageal perforations and fistulae to the airways. However, these stents cannot be used at the esophagogastric junction becaus9 there is a high incidence of stent migration when they are used at this site. Use of stents in benign disease of the esophagus is !limited by the high incidence of epithelial hyperplasia that occurs over follow-up. Stents may also be used in the relief of inoperable gastric outflow obstruction caused either by gastric or pancreatic carcinoma. The numbers of cases published in the literature are relatively small, but results indicate successful palliation with no reported complications at this time. Copyright 9 1999 by W.B. Saunders Company
elf-expanding metallic stents are well established in the
S management of strictures at many sites, including the biliary tract, tracheobronchial tree, and vascular system. Within the upper gastrointestinal tract, they are most frequently used in the esophagus, although gastric antral/pyloric and duodenal stenting have also been described. In this review, the authors outline the indications for stent insertion at the various sites within the upper gastrointestinal tract, the techniques used, results, complications, and their management.
Esophageal Stenting The majority of esophageal stents in the authors' practice are inserted for palliation of inoperable malignant dysphagia, but they are occasionally required to treat tumor recurrence at surgical anastomoses and in benign strictures unresponsive to balloon dilatation. Malignant tracheoesophageal fistulae and esophageal perforations can also be successfully treated with covered stents. Esophageal carcinoma is a relatively common disease with a poor prognosis, accounting for 3,500 deaths per year in the United Kingdom) At the time of presentation, 75% of patients will have lymph node metastases, 2 and approximately 50% to 60% of patients are not suitable for attempted curative surgical resection. Available palliative treatments include surgery;, radio-
From the Departments of Interventional Radiology and Surgery, Guy's Hospital, London, England. Address reprint requests to Mark G. Cowling, MRCP, FRCR, Department of Interventional Radiology and Surgery, 2nd Floor Guy's Tower, Guy's Hospital, St Thomas' St, London SE1 9RT, United Kingdom. Copyright 9 1999 by W.B. Saunders Company 1089-2516/99/0201-0002$10.00/0 2
therapy, chemotherapy, rigid plastic tubes, laser therapy, and self-expanding metallic esophageal stents.
Stent
Types
A variety of covered and uncovered stents are available. The three most commonly used are the Wallstent (Schneider AG, Zurich, Switzerland), t h e Strecker stent (Boston Scientific Corporation, Watertown, MA), and the Gianturco stent (William Cook, Bjaeverskov, Denmark).
The Wallstent The Wallstent is made from a stainless steel alloy tubular mesh. The initial Wallstenbdesign had a polyurethane covering on the outer surface, except for 15 mm at each end. An uncovered esophageal Wallstent is also available. The delivery system of the covered device consists of three coaxially arranged shafts within which the compressed stent is mounted. This arrangement allows partial release of the distal half of the stent, which enables repositioning before full deployment. A new design, the Flamingo esophageal stent (Schneider AG), has recently become available. In this stent, the covering is placed on the inside of the stent, allowing the mesh to be in direct contact with the esophageal mucosa, thus increasing friction and minimizing stent migration. The Flamingo stent is conical in shape, and has a braiding angle which changes between the upper and lower ends; both of these characteristics reduce the incidence of distal migration.
The Strecker Stent The uncovered Strecker stent is made from knitted nitinol, an alloy with thermal memory characteristics. This stent has a weak radial force and is now used infrequently. The new Strecker stent has a covering over the middle 75% of its length; it is compressed onto the shaft of the delivery system by a thick woven silk suture. When the stent has been correctly positioned, the suture is pulled and unravelled progressively releasing the stent. This method of release allows some adjustment of the position of the stent after initial partial distal release. A proximal release Strecker stent is also available.
The Gianturco Stent The Gianturco stent is composed of 2-cm-long basic units made from 0.018" stainless steel wire bent into a zigzag pattern. The units are sutured together to form prostheses of varying lengths. Various modifications on this basic design are available; most are covered with polyurethane and have barbs to prevent migration. The choice of stem, to some extent, depends on personal preference, but the various stents available have certain advantages and disadvantages.
Techniques in Vascularand Interventional Radiology, Vol 2, No 1 (March), 1999: pp 2-7
Technique of Insertion An initial contrast swallow is performed to delineate the site and length of stricture. The patient lies on the fluoroscopic table in the left lateral position. Xylocaine spray is applied to the pharynx, the patient is sedated with an intravenous agent such as midazolam, and analgesia is provided with an opiate such as fentanyl. A catheter and guidewire are manipulated into the duodenum to provide as stable a position as possible, and the guidewire is changed for an Amplatz stiff exchange wire (William Cook). A 15-mm diameter balloon is used to predilate the stricture before stent insertion. After dilatation, the stent is deployed according to the technique for that particular system. The authors aim to deploy the stent with approximately 60% of its length above the middle of the stricture in an effort to minimize the incidence of distal stent migration. Long strictures may require the use of more than one overlapping stent. Immediately after the procedure, nonionic contrast medium is introduced into th~ esophagus through the catheter to look for any procedural co~nplication, especially esophageal perforation, and to confirm stent patency. Patients remain in the hospital overnight, and once they have recovered from the effects of the sedation, they are allowed to ~ake small volumes of clear fluids orally. The following day, a further contrast swallow is performed with a view to proceeding to any further intervention that may be required. For example, a stent may show persistent narrowing requiring balloon dilatation, or there may have been migration, requiring the insertion of an additional stent coaxially within the first endoprosthesis and overlapping with it to prevent further slipping. If the esophagogram shows good stent position and function, patients are allowed a normal diet. They are advised to cut their food into small pieces, chew it thoroughly, and to have carbonated beverages after each meal to clear the stent of any food debris. In any patient in whom a stent has been placed across the gastroesophageal junction, reflux of gastric contents will inevitably occur. The symptoms are controlled by the administration of omeprazole, which is routinely started after the procedure.
Results of Esophageal Stenting i n M a l i g n a n t Disease The dysphagia score is used to assess the degree of dysphagia, in which 0 is equivalent to no dysphagia and 4 indicates total dysphagia (Table 1). The results of published series show immediate technical success in 100%, with improvement in the dysphagia score in 83% to 100% of patients. 3-8 Various stem designs are associated with different types of complications. Thus, the Strecker stent with its weaker radial force often requires additional postdeployment balloon dilatation. This stent is too weak to be used in cases of malignant dysphagia because of extrinsic compression. Its use in this situation has been reported to be associated with recurrent dysphagia due to TABLE 1. The Dysphagia Score Dysphagia Score
Degree of Dysphagia
0 1 2 3 4
No dysphagia Able to swallow semisolid food only Able to swallow liquids only Difficulty in swallowing liquids and saliva Complete dysphagia
ESOPHAGEAL AND UPPER GI STENTING
stent collapse, s The use of the stronger \Vallstent is recommended in the treatment of dysphagia caused by extrinsic compression. Tumor ingrowth occurs in 20% to 30% of patients, compared with only 2% of patients treated with covered stents. The lack of an outer covering probably also accounts for the absence of migration with this type of stem. Both Wallstents and Gianturco stents are associated with an incidence of 1.5% to 15% of delayed upper gastrointestinal hemorrhage. Other complications include severe pain, aspiration, pneumonia, and fistula formation. Stent migration occurs in 30% of Wallstents with an outer covering and 10% to 15% of Gianturco stents. Covered stents are particularly liable to migrate when positioned at the gastroesophageal junction, with a free end lying in the stomach. The original Wallstent design relies on the uncovered portion at either end to prevent migration, and if one end lies free in the stomach, this mechanism is compromised. In cases of complete and symptomatic stent migration, the stent can be removed by surgical gastrotomy. In cases of partial migration, the covered stent can be stabilized by the placement of a second uncovered coaxial stent through its proximal end. Because of the propensity of covered s tents placed over the gastroesophageal junction to migrate, uncovered stents are preferable to the original Wallstent.design at this site. Preliminary work has suggested that 9the Flamingo covered stentmay eliminate the problem of distal migration, 9 but further evaluation will be required to confirm this. However, the availability of a covered stent suitable for use at the esophagogastric junction is attractive, as there is minimal potential for migration without the prospect of tumor ingrowth over the long term (Fig 1). Recurrence of dysphagia secondary to tumor ingrowth or overgrowth can be successfully managed either With endoscopic laser therapy, or by the placement of additional stents. Food bolus impaction is easily cleared endoscopically.
Comparison
With Other
Techniques
Conventional palliative therapy for advanced esophageal carcinoma includes surgery, radiotherapy, and chemotherapy. Palliative surgical resection is associated with a high operative mortality and morbidity, l~ External beam radiotherapy improves dysphagia in approximately 50% of patients, but at the expense of fibrotic stricture formation in approximately 30%.~2 Intracavitary brachytherapy, either alone or in combination with external beam radiotherapy gives better resuhs, t3 but has the major drawback of causing esophagitis in up to 80% of patients. 13 Combined chemotherapy and radiotherapy also produce improved results, but at the expense of greater morbidity. 14 Rigid plastic tubes usually inserted under general anesthesia have declined in popularity in many centers. The overall complication rate has been reported to be as high as 36%, with a mortality of 2% to 16%. The reported complications include perforation in 4.2% to 10.5%, hemorrhage in 1.5% to 5%, tumor overgrowth in 8.5%, tube migration in 22%, and pressure necrosis of the esophageal wall in 4%. 15"16 The small luminal diameter leads to problems with food impaction in approximately 6.5% of patients. The use of general anesthesia and the requirement for admission to hospital for a few days also makes this treatment expensive. Laser therapy has been shown in a number of studies to provide excellent palliation in malignant esophageal obstruction. 17,18 With the use of laser 3
r
i i l 't
P
f
\
t
Fig 1. This contrast esophagogram shows a malignant stricture at the esophagogastric .junction (A). A Flamingo esophageal stent has been deployed across the stricture. The esophagogram from the day after deployment shows the stent to be patent and in a good position (B).
will be suboptimal, and there is a risk of aspiration. Esophageal therapy, more than 80% of patients can be maintained on a solid or semisolid diet. 17,18The main drawback of this modality stents and laser therapy are complementary treatments, and each case should be treated on its own merits. is the requirement for multiple treatments, which need to be repeated on a 4 to 8 weekly basis. In a series of 189 patients with inoperable esophageal carcinoma, a mean of 3.3 proceEsophageal Stents in Benign Disease dures per patient were required. ]8 The complication rate is low (5% tO 9%), 17"18and is mainly related to esophageal perforation In the majority of patients with malignant disease, the application of esophageal stents presents few long-term problems, as during pretreatment dilatation. The other main complication is most individuals have a fairly short survival. The management hemorrhage, but this can be easily controlled by local laser of benign disease is different, as in the long-term one cannot be photocoagulation. entirely certain of the difficulties that may be encountered. Both laser therapy and self-expanding metal stents are used Generally, the authors avoid the use of stents in this situation, in the authors' center for the palliation of malignant dysphagia; the), have conducted a triple randomized stud), comparing'- -but if repeat dilatation produces progressively shorter periods of relief from dysphagia, the choice is between a metallic stent "Wallstents, Strecker stents, and laser therap): The results and major surgeD: In addition, there are rare occasions when it showed statistically significantly better palliation with metallic is simply not possible to dilate benign strictures successfull): In stents than with laser therap): ~9 However, there are certain general, the authors restrict the use of self-expanding stents in morphological types of tumors in which esophageal stents are benign strictures to patients who are not fit for surgery. The use best avoided. In situations in which the tumor is very of a stent does not preclude surgery at a later date should that exophytic, or in which the esophagus is very dilated above the become necessar); and if the patient's clinical condition imstricture, the free end of the stent will not lie closely adjacent to proves sufficiently with adequate nutrition. the esophageal wall, and food or fluid will tend to pool The method of deplo)anent of esophageal stents across between the stent and the mucosa. In this situation, palliation 4
COWLING, MASON, AND ADAM
benign strictures is essentially the same as in malignant disease. The authors consider uncovered stents more appropriate as they are less likely to migrate, 19 and in this clinical setting there is no potential for tumor ingrowth, making the stent covering superfluous. An additional advantage of using uncovered stents is that after a few months, the stent is completely covered by epithelium and becomes incorporated into the wall of the esophagus. A number of cases of the use of metallic stents in benign strictures are reported in the literature, and the results indicate a good response of dysphagia. 9,2~ However, the major problem in the long term is the occurrence of epithelial hyperplasia related to the stent (Fig 2). This is amenable either to balloon dilatation or to laser treatment. The hyperplastic epithelium is generally easier to deal with than the original benign stricture, so although stents
Treatment of Malignant Esophageal Perforations and F i s t u l a e Esophageal leaks or perforations may be caused by tumor invasion, or be iatrogenic secondary to esophageal dilatation or biopsy. Fistulae to the respirator), tract may be caused by a tumor arising either from the esophagus or from the tracheobronchial tree, or may be a complication of surger),. Although perforations and leaks are generally treated conservatively in the first case, those of malignant origin may not heal. The treatment of first choice in malignant fistula or perforation is deployment of a covered stent, most commonly in the esophagus, although covered tracheal stents are also useful. The published series describing treatment of malignant esophageal fistulae with covered self-expanding stents indicates a 95% success rate in covering the fistulae and preventing leakage into the mediastinum or respiratory tract. 23 Nearly all patients have been. reported to return either to a soft or completely normal diet, as would be expected from experience with esophageal stenting of tumors.
Gastric Antral and Duodenal Stenting
%
..A
Fig 2. This elderly patient had a chronic peptic stricture which had become resistant to balloon dilatation after more than 30 treatments. She was not fit for surgery, so an uncovered Wallstent was inserted. Her symptoms recurred after 18 months, when this contrast esophagogram was performed. This shows a very narrow stricture within the stent due to epithelial hyperplasia. ESOPHAGEAL AND UPPER GI STENTING
are not ideal for the treatment of benign disease, they do at least help to make an almost unmanageable situation manageable.
The usual causes of gastric outlet obstruction are tumors in the gastric antrum, duodenal stricture, or obstruction secondary either to direct invasion or extrinsic compression from pancreatic carcinoma. Gastric outlet obstruction is traditionally palliated with a gastroenterostomy and stenting is usually carried out in patients considered unfit for surgeD: Insertion of stents by gastrostomy 24 or the peroral route has been described. 25 Endoscopy is frequently used, although is not strictly necessary; there is an absolute requirement for fluoroscop): The authors favor the peroral route under fluoroscopic guidance. After the administration of intravenous sedation, a catheter and guidewire are passed through the esophagus down to the level of the stricture in either the gastric antrum or duodenum. The catheter is manipulated across the stricture, and the guidewire changed for an Amplatz super-stiff exchange guidewire. The stricture is predilated to 10 mm in diameter, and an appropriate-sized stent is deployed. The authors favor the Wallstent because of its greater inherent outward radial force and prefer to use uncovered stents, to minimize the risk of migration; in the past, they have used 16ram diameter stents, 25 which offered a compromise between a desirable large diameter and flexibility (Fig 3). More recently they have used the enteral Wallstent, which is intended primarily for use in the colon. It has the advantage of high radial force, but as it is more flexible than the vascular Wallstent, it conforms more readily to the shape of the duodenum. The stent is 22 mm in diameter, and is available in 6 cm and 9 cm lengths. When using this stent, after balloon dilatation of the stricture, the catheter is then changed for a 95cm-long, l l F diameter Mullins transseptal sheath (William Cook). The Amplatz stiff guidewire is removed and exchanged for a 480-cm-long guidewire (William Cook). This wire is much less stiff than the Amplatz, but is required because the delivery system of the enteral stent is 255 cm long, hence the need to use the Mullins sheath to support the guidewire, and 5
Fig 3. This image is taken from a duodenal stent insertion. The patient had inoperable pancreatic carcinoma, without any associated jaundice. The tumor had spread to involve the first and second parts of the duodenum. In this image, a catheter has been positioned across the stricture, and the proximal and distal limits of the stricture can be fully appreciated (A). A contrast study was performed the day after deployment of a 16 mm x 56 mm vascular Wallstent. The stent is almost fully expanded, and contrast flows readily through it. The patient's symptoms resolved immediately after the procedure, and he was able to consume a normal diet over follow-up (B).
prevent the formation of loops xvithin the stomach. The stent is advanced on its delivery system across the stricture and, when in position, the sheath is withdrawn slightly to allow deployment of the device.
Results The number of patients reported in the literature is small, but results indicate that immediate technical success can be expected in 89% to 100%, with successful palliation of symptoms in 78% to 100%. 24-26 No major complications have been described. Given the relatively narrow stents that are used, a soft diet is advised. The authors have also successfully used metallic stents in the management of patients with pyloric dysfunction after gastric puU-up performed for esophageal carcinoma. In this situation, stents are only used if balloon dilatation has failed to alleviate symptoms.
Summary The greatest experience with self-expanding stents in the gastrointestinal tract has been in the palliation of malignant esophageal dysphagia. Results are excellent with a low complication rate. Tumor ingrowth through the stent mesh remains a problem, and modifications in stent design will be required to address this. Stents in the gastric antrum and duodenum are 6
useful in the relief of malignant gastric outlet obstruction in selected patients.
References 1. Earlam R: Esophageal cancer treatment in North East Thames Region in 1981: Medical audit using hospital activity analysis data. Br Med J 288:1892-1894, 1984 2. Rankin S, Mason R: Staging of esophageal carcinoma. Clin Radiol 46:373-377, 1992 3. Cwikiel W, Stridbeck H, Tranberg KG, et al: Malignant esophageal strictures: Treatment with a self-expanding nitinol stent. Radiology 187;661-665, 1993 4. Saxon RR, Barton RE, Katon RM, et al: Treatment of malignant esophageal obstructions with covered metallic Z stents: Long-term results in 52 patients. J Vasc Interv Radiol 6:747-754, 1995 5. Miyayama S, Matsui O, Kadoya M, et al: Malignant esophageal stricture and fistula: Palliative treatment with polyurethane-covered Gianturco stent. J Vase Intenl Radiol 6:243-248, 1995 6. May A, Selmaier M, Hochberger J, et al: Memory metal stents for palliation of malignant obstruction of the esophagus and cardia. Gut 37:309-313, 1995 7. Song HY, Do YS, Han YM, et al: Covered, expandable esophageal metallic stent tubes: Experiences in 119 patients. Radiology 193:689695, 1994 8. Cowling MG, Hale H, Grundy A: The use of self-expanding metal stents in the management of malignant esophageal strictures. Br J Surg 85:264-266, 1998 COWLING, MASON, AND ADAM
9. Adam A, Morgan R, E[lul J, et al: A new design of the esophageal Wallstent endoprosthesis resistant to distal migration. Am J Roentgeno1170:1477-1481 10. Earlam R, Chunha-Melo JR: Esophageal squamous cell carcinoma: 1. A critical review of surgery. Br J Surg 67:381-390, 1980 11. Muller JM, Erasmi H, Stelzner M, et al: Surgical therapy of esophageal carcinoma. BrJ Surg 77:845-857, 1990 12. Earlam R, Chunha-Melo JR: Esophageal squamous cell carcinoma: II. A critical review of radiotherapy. Br J Surg 67:457-461, 1980 13. Harvey JC, Fleischman EH, Belloti JE, et al: Intracavitary radiation in the treatment of advanced esophageal carcinoma: A comparison of high dose rate vs. low dose rate brachytherapy. J Surg Oncol 52:101-104, 1993 14. Herskovic A, Martz K, AI-Sarraf M, et al: Combined chemotherapy and radiotherapy compared to radiotherapy alone in patients with cancer of the esophagus. New Engl J Med 326:1593-1598, 1992 15. Tytgat GNJ: Endoscopic therapy of esophageal cancer: Possibilities and limitations. Endoscopy 22:263-267, 1990 16. Gasparri G, Casalegno PA, Camadona M, et al: Endoscopic insertion of 248 prostheses in inoperable carcinoma of the esophagus and cardia: Short-term and long-term results. Gastrointest Endosc 33:354356, 1987 17. Sander RR, Poesl H: Cancer of the esophagus-palliation-laser treatment and combined procedures. Endoscopy 25:679-682, 1993 (suppl)
ESOPHAGEAL AND UPPER GI STENTING
18. Mason RC, Bright N, McColl I: Palliation of malignant dysphagia with laser therapy: Predictability of results. Br J Surg 78:1346-1347, 1991 19. Adam A, Ellul J, Watkinson AF, et al: Palliation of inoperable esophageal carcinoma: A prospective randomized trial of laser therapy and stent placement. Radiology 202:344-348, 1997 20. Cwikiel W, WilIen R, Stridbeck H, et al: Self-expanding stent in the treatment of benign esophageal strictures: Experimental study in pigs and presentation of clinical cases. Radiology 187:667-671, 1993 21. Foster DR: Use of a Strecker esophageal stent in the treatment of benign esophageal stricture. Australas Radio139:399-400, 1995 22. Tan BS, Kennedy C, Morgan R, et al: Uncovered metallic endoprostheses for recurrent benign esophageal strictures: Preliminary experience. Am J Roent geno1169:1281-1284, 1997 23. Morgan RA, Ellul JPM, Denton ERE, et al: Malignant esophageal fistulas and perforations: Management with plastic-covered metallic endoprostheses. Radiology 204:527-532, 1997 24. Keymling M, Wagner H-J, Vakil N, et al: Relief of malignant duodenal obstruction by percutaneous insertion of a metal stent. Gastrointest Endosc 39:439-441, 1993 25. Scott-Mackie P, Morgan R, Farrugia M, et al: Malignant duodenal obstruction: A role for metallic stents. Br J Radio170:252-255, 1997 26. Binkert CA, Jost R, SteinerA, eta!: Benign and malignant stenoses of the stomach and duodenum: Treatment with self-expanding metallic endoprostheses. Radiology 199:335-338, 1996
7
Self-expanding metallic stents are now well established in the palliative management of inoperable esophageal carcinoma. Dysphagia is successfully palliated in more than 90% of patients treated, with a low incidence of procedural complications. Use of covered stents minimizes recurrent dysphagia due to tumor ingrowth, and also provides palliation for the vast majority of malignant esophageal perforations and fistulae to the airways. However, these stents cannot be used at the esophagogastric junction becaus9 there is a high incidence of stent migration when they are used at this site. Use of stents in benign disease of the esophagus is !limited by the high incidence of epithelial hyperplasia that occurs over follow-up. Stents may also be used in the relief of inoperable gastric outflow obstruction caused either by gastric or pancreatic carcinoma. The numbers of cases published in the literature are relatively small, but results indicate successful palliation with no reported complications at this time. Copyright 9 1999 by W.B. Saunders Company
elf-expanding metallic stents are well established in the
S management of strictures at many sites, including the biliary tract, tracheobronchial tree, and vascular system. Within the upper gastrointestinal tract, they are most frequently used in the esophagus, although gastric antral/pyloric and duodenal stenting have also been described. In this review, the authors outline the indications for stent insertion at the various sites within the upper gastrointestinal tract, the techniques used, results, complications, and their management.
Esophageal Stenting The majority of esophageal stents in the authors' practice are inserted for palliation of inoperable malignant dysphagia, but they are occasionally required to treat tumor recurrence at surgical anastomoses and in benign strictures unresponsive to balloon dilatation. Malignant tracheoesophageal fistulae and esophageal perforations can also be successfully treated with covered stents. Esophageal carcinoma is a relatively common disease with a poor prognosis, accounting for 3,500 deaths per year in the United Kingdom) At the time of presentation, 75% of patients will have lymph node metastases, 2 and approximately 50% to 60% of patients are not suitable for attempted curative surgical resection. Available palliative treatments include surgery;, radio-
From the Departments of Interventional Radiology and Surgery, Guy's Hospital, London, England. Address reprint requests to Mark G. Cowling, MRCP, FRCR, Department of Interventional Radiology and Surgery, 2nd Floor Guy's Tower, Guy's Hospital, St Thomas' St, London SE1 9RT, United Kingdom. Copyright 9 1999 by W.B. Saunders Company 1089-2516/99/0201-0002$10.00/0 2
therapy, chemotherapy, rigid plastic tubes, laser therapy, and self-expanding metallic esophageal stents.
Stent
Types
A variety of covered and uncovered stents are available. The three most commonly used are the Wallstent (Schneider AG, Zurich, Switzerland), t h e Strecker stent (Boston Scientific Corporation, Watertown, MA), and the Gianturco stent (William Cook, Bjaeverskov, Denmark).
The Wallstent The Wallstent is made from a stainless steel alloy tubular mesh. The initial Wallstenbdesign had a polyurethane covering on the outer surface, except for 15 mm at each end. An uncovered esophageal Wallstent is also available. The delivery system of the covered device consists of three coaxially arranged shafts within which the compressed stent is mounted. This arrangement allows partial release of the distal half of the stent, which enables repositioning before full deployment. A new design, the Flamingo esophageal stent (Schneider AG), has recently become available. In this stent, the covering is placed on the inside of the stent, allowing the mesh to be in direct contact with the esophageal mucosa, thus increasing friction and minimizing stent migration. The Flamingo stent is conical in shape, and has a braiding angle which changes between the upper and lower ends; both of these characteristics reduce the incidence of distal migration.
The Strecker Stent The uncovered Strecker stent is made from knitted nitinol, an alloy with thermal memory characteristics. This stent has a weak radial force and is now used infrequently. The new Strecker stent has a covering over the middle 75% of its length; it is compressed onto the shaft of the delivery system by a thick woven silk suture. When the stent has been correctly positioned, the suture is pulled and unravelled progressively releasing the stent. This method of release allows some adjustment of the position of the stent after initial partial distal release. A proximal release Strecker stent is also available.
The Gianturco Stent The Gianturco stent is composed of 2-cm-long basic units made from 0.018" stainless steel wire bent into a zigzag pattern. The units are sutured together to form prostheses of varying lengths. Various modifications on this basic design are available; most are covered with polyurethane and have barbs to prevent migration. The choice of stem, to some extent, depends on personal preference, but the various stents available have certain advantages and disadvantages.
Techniques in Vascularand Interventional Radiology, Vol 2, No 1 (March), 1999: pp 2-7
Technique of Insertion An initial contrast swallow is performed to delineate the site and length of stricture. The patient lies on the fluoroscopic table in the left lateral position. Xylocaine spray is applied to the pharynx, the patient is sedated with an intravenous agent such as midazolam, and analgesia is provided with an opiate such as fentanyl. A catheter and guidewire are manipulated into the duodenum to provide as stable a position as possible, and the guidewire is changed for an Amplatz stiff exchange wire (William Cook). A 15-mm diameter balloon is used to predilate the stricture before stent insertion. After dilatation, the stent is deployed according to the technique for that particular system. The authors aim to deploy the stent with approximately 60% of its length above the middle of the stricture in an effort to minimize the incidence of distal stent migration. Long strictures may require the use of more than one overlapping stent. Immediately after the procedure, nonionic contrast medium is introduced into th~ esophagus through the catheter to look for any procedural co~nplication, especially esophageal perforation, and to confirm stent patency. Patients remain in the hospital overnight, and once they have recovered from the effects of the sedation, they are allowed to ~ake small volumes of clear fluids orally. The following day, a further contrast swallow is performed with a view to proceeding to any further intervention that may be required. For example, a stent may show persistent narrowing requiring balloon dilatation, or there may have been migration, requiring the insertion of an additional stent coaxially within the first endoprosthesis and overlapping with it to prevent further slipping. If the esophagogram shows good stent position and function, patients are allowed a normal diet. They are advised to cut their food into small pieces, chew it thoroughly, and to have carbonated beverages after each meal to clear the stent of any food debris. In any patient in whom a stent has been placed across the gastroesophageal junction, reflux of gastric contents will inevitably occur. The symptoms are controlled by the administration of omeprazole, which is routinely started after the procedure.
Results of Esophageal Stenting i n M a l i g n a n t Disease The dysphagia score is used to assess the degree of dysphagia, in which 0 is equivalent to no dysphagia and 4 indicates total dysphagia (Table 1). The results of published series show immediate technical success in 100%, with improvement in the dysphagia score in 83% to 100% of patients. 3-8 Various stem designs are associated with different types of complications. Thus, the Strecker stent with its weaker radial force often requires additional postdeployment balloon dilatation. This stent is too weak to be used in cases of malignant dysphagia because of extrinsic compression. Its use in this situation has been reported to be associated with recurrent dysphagia due to TABLE 1. The Dysphagia Score Dysphagia Score
Degree of Dysphagia
0 1 2 3 4
No dysphagia Able to swallow semisolid food only Able to swallow liquids only Difficulty in swallowing liquids and saliva Complete dysphagia
ESOPHAGEAL AND UPPER GI STENTING
stent collapse, s The use of the stronger \Vallstent is recommended in the treatment of dysphagia caused by extrinsic compression. Tumor ingrowth occurs in 20% to 30% of patients, compared with only 2% of patients treated with covered stents. The lack of an outer covering probably also accounts for the absence of migration with this type of stem. Both Wallstents and Gianturco stents are associated with an incidence of 1.5% to 15% of delayed upper gastrointestinal hemorrhage. Other complications include severe pain, aspiration, pneumonia, and fistula formation. Stent migration occurs in 30% of Wallstents with an outer covering and 10% to 15% of Gianturco stents. Covered stents are particularly liable to migrate when positioned at the gastroesophageal junction, with a free end lying in the stomach. The original Wallstent design relies on the uncovered portion at either end to prevent migration, and if one end lies free in the stomach, this mechanism is compromised. In cases of complete and symptomatic stent migration, the stent can be removed by surgical gastrotomy. In cases of partial migration, the covered stent can be stabilized by the placement of a second uncovered coaxial stent through its proximal end. Because of the propensity of covered s tents placed over the gastroesophageal junction to migrate, uncovered stents are preferable to the original Wallstent.design at this site. Preliminary work has suggested that 9the Flamingo covered stentmay eliminate the problem of distal migration, 9 but further evaluation will be required to confirm this. However, the availability of a covered stent suitable for use at the esophagogastric junction is attractive, as there is minimal potential for migration without the prospect of tumor ingrowth over the long term (Fig 1). Recurrence of dysphagia secondary to tumor ingrowth or overgrowth can be successfully managed either With endoscopic laser therapy, or by the placement of additional stents. Food bolus impaction is easily cleared endoscopically.
Comparison
With Other
Techniques
Conventional palliative therapy for advanced esophageal carcinoma includes surgery, radiotherapy, and chemotherapy. Palliative surgical resection is associated with a high operative mortality and morbidity, l~ External beam radiotherapy improves dysphagia in approximately 50% of patients, but at the expense of fibrotic stricture formation in approximately 30%.~2 Intracavitary brachytherapy, either alone or in combination with external beam radiotherapy gives better resuhs, t3 but has the major drawback of causing esophagitis in up to 80% of patients. 13 Combined chemotherapy and radiotherapy also produce improved results, but at the expense of greater morbidity. 14 Rigid plastic tubes usually inserted under general anesthesia have declined in popularity in many centers. The overall complication rate has been reported to be as high as 36%, with a mortality of 2% to 16%. The reported complications include perforation in 4.2% to 10.5%, hemorrhage in 1.5% to 5%, tumor overgrowth in 8.5%, tube migration in 22%, and pressure necrosis of the esophageal wall in 4%. 15"16 The small luminal diameter leads to problems with food impaction in approximately 6.5% of patients. The use of general anesthesia and the requirement for admission to hospital for a few days also makes this treatment expensive. Laser therapy has been shown in a number of studies to provide excellent palliation in malignant esophageal obstruction. 17,18 With the use of laser 3
r
i i l 't
P
f
\
t
Fig 1. This contrast esophagogram shows a malignant stricture at the esophagogastric .junction (A). A Flamingo esophageal stent has been deployed across the stricture. The esophagogram from the day after deployment shows the stent to be patent and in a good position (B).
will be suboptimal, and there is a risk of aspiration. Esophageal therapy, more than 80% of patients can be maintained on a solid or semisolid diet. 17,18The main drawback of this modality stents and laser therapy are complementary treatments, and each case should be treated on its own merits. is the requirement for multiple treatments, which need to be repeated on a 4 to 8 weekly basis. In a series of 189 patients with inoperable esophageal carcinoma, a mean of 3.3 proceEsophageal Stents in Benign Disease dures per patient were required. ]8 The complication rate is low (5% tO 9%), 17"18and is mainly related to esophageal perforation In the majority of patients with malignant disease, the application of esophageal stents presents few long-term problems, as during pretreatment dilatation. The other main complication is most individuals have a fairly short survival. The management hemorrhage, but this can be easily controlled by local laser of benign disease is different, as in the long-term one cannot be photocoagulation. entirely certain of the difficulties that may be encountered. Both laser therapy and self-expanding metal stents are used Generally, the authors avoid the use of stents in this situation, in the authors' center for the palliation of malignant dysphagia; the), have conducted a triple randomized stud), comparing'- -but if repeat dilatation produces progressively shorter periods of relief from dysphagia, the choice is between a metallic stent "Wallstents, Strecker stents, and laser therap): The results and major surgeD: In addition, there are rare occasions when it showed statistically significantly better palliation with metallic is simply not possible to dilate benign strictures successfull): In stents than with laser therap): ~9 However, there are certain general, the authors restrict the use of self-expanding stents in morphological types of tumors in which esophageal stents are benign strictures to patients who are not fit for surgery. The use best avoided. In situations in which the tumor is very of a stent does not preclude surgery at a later date should that exophytic, or in which the esophagus is very dilated above the become necessar); and if the patient's clinical condition imstricture, the free end of the stent will not lie closely adjacent to proves sufficiently with adequate nutrition. the esophageal wall, and food or fluid will tend to pool The method of deplo)anent of esophageal stents across between the stent and the mucosa. In this situation, palliation 4
COWLING, MASON, AND ADAM
benign strictures is essentially the same as in malignant disease. The authors consider uncovered stents more appropriate as they are less likely to migrate, 19 and in this clinical setting there is no potential for tumor ingrowth, making the stent covering superfluous. An additional advantage of using uncovered stents is that after a few months, the stent is completely covered by epithelium and becomes incorporated into the wall of the esophagus. A number of cases of the use of metallic stents in benign strictures are reported in the literature, and the results indicate a good response of dysphagia. 9,2~ However, the major problem in the long term is the occurrence of epithelial hyperplasia related to the stent (Fig 2). This is amenable either to balloon dilatation or to laser treatment. The hyperplastic epithelium is generally easier to deal with than the original benign stricture, so although stents
Treatment of Malignant Esophageal Perforations and F i s t u l a e Esophageal leaks or perforations may be caused by tumor invasion, or be iatrogenic secondary to esophageal dilatation or biopsy. Fistulae to the respirator), tract may be caused by a tumor arising either from the esophagus or from the tracheobronchial tree, or may be a complication of surger),. Although perforations and leaks are generally treated conservatively in the first case, those of malignant origin may not heal. The treatment of first choice in malignant fistula or perforation is deployment of a covered stent, most commonly in the esophagus, although covered tracheal stents are also useful. The published series describing treatment of malignant esophageal fistulae with covered self-expanding stents indicates a 95% success rate in covering the fistulae and preventing leakage into the mediastinum or respiratory tract. 23 Nearly all patients have been. reported to return either to a soft or completely normal diet, as would be expected from experience with esophageal stenting of tumors.
Gastric Antral and Duodenal Stenting
%
..A
Fig 2. This elderly patient had a chronic peptic stricture which had become resistant to balloon dilatation after more than 30 treatments. She was not fit for surgery, so an uncovered Wallstent was inserted. Her symptoms recurred after 18 months, when this contrast esophagogram was performed. This shows a very narrow stricture within the stent due to epithelial hyperplasia. ESOPHAGEAL AND UPPER GI STENTING
are not ideal for the treatment of benign disease, they do at least help to make an almost unmanageable situation manageable.
The usual causes of gastric outlet obstruction are tumors in the gastric antrum, duodenal stricture, or obstruction secondary either to direct invasion or extrinsic compression from pancreatic carcinoma. Gastric outlet obstruction is traditionally palliated with a gastroenterostomy and stenting is usually carried out in patients considered unfit for surgeD: Insertion of stents by gastrostomy 24 or the peroral route has been described. 25 Endoscopy is frequently used, although is not strictly necessary; there is an absolute requirement for fluoroscop): The authors favor the peroral route under fluoroscopic guidance. After the administration of intravenous sedation, a catheter and guidewire are passed through the esophagus down to the level of the stricture in either the gastric antrum or duodenum. The catheter is manipulated across the stricture, and the guidewire changed for an Amplatz super-stiff exchange guidewire. The stricture is predilated to 10 mm in diameter, and an appropriate-sized stent is deployed. The authors favor the Wallstent because of its greater inherent outward radial force and prefer to use uncovered stents, to minimize the risk of migration; in the past, they have used 16ram diameter stents, 25 which offered a compromise between a desirable large diameter and flexibility (Fig 3). More recently they have used the enteral Wallstent, which is intended primarily for use in the colon. It has the advantage of high radial force, but as it is more flexible than the vascular Wallstent, it conforms more readily to the shape of the duodenum. The stent is 22 mm in diameter, and is available in 6 cm and 9 cm lengths. When using this stent, after balloon dilatation of the stricture, the catheter is then changed for a 95cm-long, l l F diameter Mullins transseptal sheath (William Cook). The Amplatz stiff guidewire is removed and exchanged for a 480-cm-long guidewire (William Cook). This wire is much less stiff than the Amplatz, but is required because the delivery system of the enteral stent is 255 cm long, hence the need to use the Mullins sheath to support the guidewire, and 5
Fig 3. This image is taken from a duodenal stent insertion. The patient had inoperable pancreatic carcinoma, without any associated jaundice. The tumor had spread to involve the first and second parts of the duodenum. In this image, a catheter has been positioned across the stricture, and the proximal and distal limits of the stricture can be fully appreciated (A). A contrast study was performed the day after deployment of a 16 mm x 56 mm vascular Wallstent. The stent is almost fully expanded, and contrast flows readily through it. The patient's symptoms resolved immediately after the procedure, and he was able to consume a normal diet over follow-up (B).
prevent the formation of loops xvithin the stomach. The stent is advanced on its delivery system across the stricture and, when in position, the sheath is withdrawn slightly to allow deployment of the device.
Results The number of patients reported in the literature is small, but results indicate that immediate technical success can be expected in 89% to 100%, with successful palliation of symptoms in 78% to 100%. 24-26 No major complications have been described. Given the relatively narrow stents that are used, a soft diet is advised. The authors have also successfully used metallic stents in the management of patients with pyloric dysfunction after gastric puU-up performed for esophageal carcinoma. In this situation, stents are only used if balloon dilatation has failed to alleviate symptoms.
Summary The greatest experience with self-expanding stents in the gastrointestinal tract has been in the palliation of malignant esophageal dysphagia. Results are excellent with a low complication rate. Tumor ingrowth through the stent mesh remains a problem, and modifications in stent design will be required to address this. Stents in the gastric antrum and duodenum are 6
useful in the relief of malignant gastric outlet obstruction in selected patients.
References 1. Earlam R: Esophageal cancer treatment in North East Thames Region in 1981: Medical audit using hospital activity analysis data. Br Med J 288:1892-1894, 1984 2. Rankin S, Mason R: Staging of esophageal carcinoma. Clin Radiol 46:373-377, 1992 3. Cwikiel W, Stridbeck H, Tranberg KG, et al: Malignant esophageal strictures: Treatment with a self-expanding nitinol stent. Radiology 187;661-665, 1993 4. Saxon RR, Barton RE, Katon RM, et al: Treatment of malignant esophageal obstructions with covered metallic Z stents: Long-term results in 52 patients. J Vasc Interv Radiol 6:747-754, 1995 5. Miyayama S, Matsui O, Kadoya M, et al: Malignant esophageal stricture and fistula: Palliative treatment with polyurethane-covered Gianturco stent. J Vase Intenl Radiol 6:243-248, 1995 6. May A, Selmaier M, Hochberger J, et al: Memory metal stents for palliation of malignant obstruction of the esophagus and cardia. Gut 37:309-313, 1995 7. Song HY, Do YS, Han YM, et al: Covered, expandable esophageal metallic stent tubes: Experiences in 119 patients. Radiology 193:689695, 1994 8. Cowling MG, Hale H, Grundy A: The use of self-expanding metal stents in the management of malignant esophageal strictures. Br J Surg 85:264-266, 1998 COWLING, MASON, AND ADAM
9. Adam A, Morgan R, E[lul J, et al: A new design of the esophageal Wallstent endoprosthesis resistant to distal migration. Am J Roentgeno1170:1477-1481 10. Earlam R, Chunha-Melo JR: Esophageal squamous cell carcinoma: 1. A critical review of surgery. Br J Surg 67:381-390, 1980 11. Muller JM, Erasmi H, Stelzner M, et al: Surgical therapy of esophageal carcinoma. BrJ Surg 77:845-857, 1990 12. Earlam R, Chunha-Melo JR: Esophageal squamous cell carcinoma: II. A critical review of radiotherapy. Br J Surg 67:457-461, 1980 13. Harvey JC, Fleischman EH, Belloti JE, et al: Intracavitary radiation in the treatment of advanced esophageal carcinoma: A comparison of high dose rate vs. low dose rate brachytherapy. J Surg Oncol 52:101-104, 1993 14. Herskovic A, Martz K, AI-Sarraf M, et al: Combined chemotherapy and radiotherapy compared to radiotherapy alone in patients with cancer of the esophagus. New Engl J Med 326:1593-1598, 1992 15. Tytgat GNJ: Endoscopic therapy of esophageal cancer: Possibilities and limitations. Endoscopy 22:263-267, 1990 16. Gasparri G, Casalegno PA, Camadona M, et al: Endoscopic insertion of 248 prostheses in inoperable carcinoma of the esophagus and cardia: Short-term and long-term results. Gastrointest Endosc 33:354356, 1987 17. Sander RR, Poesl H: Cancer of the esophagus-palliation-laser treatment and combined procedures. Endoscopy 25:679-682, 1993 (suppl)
ESOPHAGEAL AND UPPER GI STENTING
18. Mason RC, Bright N, McColl I: Palliation of malignant dysphagia with laser therapy: Predictability of results. Br J Surg 78:1346-1347, 1991 19. Adam A, Ellul J, Watkinson AF, et al: Palliation of inoperable esophageal carcinoma: A prospective randomized trial of laser therapy and stent placement. Radiology 202:344-348, 1997 20. Cwikiel W, WilIen R, Stridbeck H, et al: Self-expanding stent in the treatment of benign esophageal strictures: Experimental study in pigs and presentation of clinical cases. Radiology 187:667-671, 1993 21. Foster DR: Use of a Strecker esophageal stent in the treatment of benign esophageal stricture. Australas Radio139:399-400, 1995 22. Tan BS, Kennedy C, Morgan R, et al: Uncovered metallic endoprostheses for recurrent benign esophageal strictures: Preliminary experience. Am J Roent geno1169:1281-1284, 1997 23. Morgan RA, Ellul JPM, Denton ERE, et al: Malignant esophageal fistulas and perforations: Management with plastic-covered metallic endoprostheses. Radiology 204:527-532, 1997 24. Keymling M, Wagner H-J, Vakil N, et al: Relief of malignant duodenal obstruction by percutaneous insertion of a metal stent. Gastrointest Endosc 39:439-441, 1993 25. Scott-Mackie P, Morgan R, Farrugia M, et al: Malignant duodenal obstruction: A role for metallic stents. Br J Radio170:252-255, 1997 26. Binkert CA, Jost R, SteinerA, eta!: Benign and malignant stenoses of the stomach and duodenum: Treatment with self-expanding metallic endoprostheses. Radiology 199:335-338, 1996
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