Esophageal Endoprostheses

The insertion of esophageal endoprostheses or stents is a common approach to the palliative management of dysphagia (Baron, 2001; Siersema et al, 2003). Stent placement should only be undertaken after very careful scrutiny of the clinical situation (eg, tumor stage, length, position, and expected prognosis of the patient). Because of the potential complications associated with stent placement (eg, stent migration, perforation, and stent tumor ingrowth or overgrowth), consideration of these factors is especially important before stent placement. A stent should be considered permanent after deployment and is the ultimate form of palliation before the patient dies. The risk of stent-associated complications is increased if patients subsequently undergo chemoradiation or radiation therapy. To minimize the risks associated with stent placement, tumors that can be adequately treated with thermal or PDT ablative therapies should first be treated in that fashion for as long as possible before stent placement is contemplated. If the stent is patent and the patient still complains of dysphagia, the patient needs to be considered for radiation and chemotherapy, although it is unlikely that radiation or chemotherapy will prolong either survival or quality of life. Before stent placement, endoscopic examination of the tumor should be carried out to measure the lesional length, location, and the distance from the lesion to the upper or lower esophageal sphincters. Generally, the stent should be 4 to 6 cm longer than the tumor, allowing 2 cm above and below the lesion. During stent placement,

FIGURE 22-5. Polyflex covered plastic stent.

Most available data on SEMS is retrospective and uncontrolled. The immediate palliation of malignant dysphagia with SEMS is 78 to 96%, with a stent migration rate of 4 to 9%, a tumor ingrowth of 3 to 37%, a need for subsequent intervention rate of 3 to 78%, and a major complications (ie, bleeding, perforation, aspiration, and fistula) rate of 3 to 17%. Most metal stents are safe if patients undergo magnetic resonance imaging (Table 22-1).

There are four commonly used covered metal stents for esophageal stenting: Ultraflex stent (Microvasive/Boston Scientific, Natick, Massachusetts), Wallstent II (Boston Scientific), Flamingo Wallstent (Boston Scientific, available only in Europe), and Gianturco-Z stent (Wilson-Cook Medical, Winston-Salem, North Carolina) (see Table 22-1 and Figures 22-6 to 22-8). In one randomized trial, there was no difference in rates of dysphagia improvement, subsequent recurrence of dysphagia (24 to 36%), or complica tion (18 to 36%) between the Ultraflex stent, the Flamingo Wallstent, or the Z stent (Siersema et al, 2001). In another study comparing covered with uncovered SEMS, there was a higher tumor ingrowth rate in the uncovered SEMS arm (30 versus 3%) leading to a significantly higher endoscopic reintervention rate (27 versus 0%). However, there was no difference in patient survival or quality of life measures between the two arms. Data comparing the SEMS to other therapeutic modalities available for palliation of EC is limited. One randomized trial compared SEMS with combination therapy of endoscopic laser therapy/external beam radiotherapy in patients with cancer that was not resectable. It found no difference in rates of dysphagia improvement or survival advantage between the two palliation arms. However, there was a lower incidence of restenosis and major complications in the SEMS arm. Stenting was also demonstrated to be more cost effective.

TABLE 22-1. Specifics of US Food and Drug Administration-Approved Expandable Metal Stents for Esophageal Use in North America

Ultraflex

Wallstent II

Z Stent

Material

Nitinol

Elgiloy

Stainless steel

Covering

Yes

Yes

Yes

Design

Mesh

Mesh

Zigzag

Radial Force

+

+++

++

Lumen diagmeter

(mm) (flanges/shaft)

23-28/17-22

28/20

21-25/18-22

Covered length (cm)

7-12

8, 13

8-14

Degree of foreshortening*

up to 30%

» 20%

0%

MRI-friendly

Yes

Yes

No

MRI = magnetic resonance imaging.

* Stent foreshortening generally will not affect stent deployment. The Ultraflex has postdeploy-

ment radiopaque markers that indicate exactly where the stent will reside after deployment. fThe foreshortening is variable depending on the nature of the stricture and compression of the stent within that stricture.

MRI = magnetic resonance imaging.

* Stent foreshortening generally will not affect stent deployment. The Ultraflex has postdeploy-

ment radiopaque markers that indicate exactly where the stent will reside after deployment. fThe foreshortening is variable depending on the nature of the stricture and compression of the stent within that stricture.

Cook Medical Esophageal Stent
FIGURE 22-6. US Food and Drug Administration-approved covered expandable metal stents for esophageal use in North America, from the left to the right: Ultraflex stent, Wallstent II, and Z stent.
Esophageal Stent With Valve
FIGURE 22-7. Z stent with antireflux valve.
Wallstent Deployment
FIGURE 22-8. Endoscopic view of an Ultraflex stent deployed in the esophagus.

There are several special situations concerning esophageal stent placement. For malignant intraluminal cancers located near the upper sphincter, if the tumor is within 2 to 3 cm of the upper sphincter, SEMS can be placed; however, careful positioning with metallic markers and maintenance of the patient in a supine position is usually needed during stent placement. The more difficult situation is when the tumor invades the upper sphincter. In these situations, thermal therapy or PDT could be tried. The issues are tracheal compression or foreign body sensation after stent deployment. A small caliber plastic tube could be used in connection with a feeding gastrostomy. There have been reports using Montgomery salivary bypass tubes (Boston Scientific, Natick, Massachusetts), latex rubber tubes (Celestin, Medoc Ltd, Atlanta, Georgia.) or Tygon polyvinyl endoprostheses for palliation in the cervical esophagus (Weigel et al, 2002). In cases of extrinsic compression and infiltration of the esophagus from metastatic, pulmonary or lymphatic malignancies without a shelf in the esophagus, dilatation followed by placement of stent with wide flange can be tried. To minimize stent migration, in some instances, endoscopically placed clips may be used to prevent stent migration, especially in patients where the stricture is extrinsic and/or not overly tight. Another way is to anchor the stent with an umbilical thread passed transnasally and overhung around the ear (Hujala et al, 2002). The availability of covered SEMS has significantly changed the management of TEF, esophageal fistulas, or perforation resulting from other palliative measures.

Untreated TEF carries a very poor prognosis primarily from aspiration pneumonia and the covered SEMS has become the first line of treatment. Closure of the fistula is achieved in 70 to 100% of patients with SEMS. For persistent TEF despite stent placement, placement of an airway stent should be considered to close the fistula. It should be noted that placement of an SEMS does not prevent further subsequent enlargement of the existing fistula or development of further fistulas (Heindorff et al, 1998).

Aspiration precautions, such as elevation of the head of the bed and aggressive acid suppression with proton pump inhibitors, are needed to prevent aspiration and reflux if a stent without an antireflux mechanism is placed across the gastroesophageal (GE) junction. An esophageal stent with an antireflux device may be of value under such circumstances.

Stent occlusion and migration are the most significant complications occurring in long term cancer survivors. Stent occlusion is caused by tumor overgrowth and by reactive tissue hyperplasia/granulation tissue. APC, Nd:YAG laser, PDT, or placement of a second overlapping stent can be considered to relieve the occlusion. For very long and large tumors, placement of two overlapping stents can minimize tumor overgrowth. Dietary precautions should be practiced by all patients, such as adherence to a mechanical soft or pureed diet to prevent food impaction within or above the stent. Stents tend to migrate more commonly distally than proximally. Long circumferential tumors minimize stent migration. The approach to migration depends on the type of stent, extent of migration, and whether any complications have occurred as a consequence of migration. Chemoradiation or radiation therapy predisposes the pre-placed stent to migrate due to tumor shrinkage. The migration rate may be affected by stent diameter with larger caliber stents being less likely to migrate, but this finding has to be balanced by the possibility that larger caliber stents may increase the rate of complication from stent erosion through the esophageal wall. Finally partially covered stents with wider distal flanges may prove useful in reducing the rate of stent migration, although this is not proven by the available data. Ongoing advances in endoprostheses material and design aim to reduce tissue overgrowth, stent migration, and acid reflux in cases where the stent traverses the GE junction. For cases where the stent has migrated into the stomach, controversy exists over whether to adopt a "watchful waiting approach" or whether to try to remove the stent immediately. If the migrated stent in the stomach interferes with gastric emptying and the patient's functional status is good, the stent could be removed either endoscopically or by laparotomy.

Based on current data, no particular type of SEMS can be recommended to be ideal for all causes of malignant dysphagia. Local resource availability, technical expertise and familiarity, and other factors need to be considered during the decision-making process.

Constipation Prescription

Constipation Prescription

Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.

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