44: Techniques for Dilation of Benign Esophageal Stricture

Benign strictures of the esophagus usually result from scarring and subsequent tissue contraction secondary to esophageal wall injury. This pathology is caused in most cases by long-standing gastroesophageal reflux disease (GERD), often in association with one of the esophageal motility disorders (e.g., achalasia, diffuse esophageal spasm, or aperistalsis).^1,2 Endoscopic dilation of benign esophageal strictures that are refractory to medical management is a less morbid alternative to surgery. Approximately 20% to 30% of cases are unrelated to GERD, and their treatment usually is more challenging. Examples include strictures arising from complications of surgical anastomosis,³ injuries caused by caustic ingestions, early and late consequences of external-beam radiation, esophageal sclerotherapy, laser or photodynamic therapy, medication- or pill-induced esophagitis that is associated with numerous medications (e.g., alendronate, ferrous sulfate, nonsteroidal anti-inflammatory drugs, phenytoin, potassium chloride, quinicline, tetracycline, and ascorbic acid) but most often aspirin, and rare dermatologic diseases, including epidermolysis bullosa dystrophica, among others.

Benign strictures also may result from external compression of the esophagus caused by mediastinal fibrosis induced by tuberculosis, fungal infection, radiation therapy, or idiopathic fibrosing mediastinitis. These conditions may give rise to long, narrow strictures that are difficult to dilate and in which dilation may be associated with a higher rate of complications.

Dysphagia is the most common presenting symptom of benign esophageal stricture. The degree of dysphagia is proportional to the scope (e.g., length) of the stricture and the luminal diameter of the esophagus (<13-mm diameter is associated with dysphagia to solids, >18-mm luminal diameter for normal swallowing). As the stenosis worsens over time, the dysphagia progresses from solid to semisolid to liquid foods. The etiology of the esophageal stricture usually can be identified using radiographic modalities and is confirmed by endoscopic visualization and tissue biopsy. Manometry is the defining diagnostic procedure when esophageal dysmotility is suspected as the primary inciting process. CT scan and endoscopic ultrasound are valuable diagnostic aids that can distinguish benign from malignant strictures. Fortunately, most benign esophageal strictures are amenable to single or combined pharmacologic, endoscopic, or surgical intervention.

The goal of therapy for benign esophageal stricture is twofold: to relieve the patient's dysphagia and to prevent recurrence of the stricture.⁴ Conservative and surgical approaches to management are recommended depending on the etiology of the inciting injury. Surgical and medical issues related to esophageal dilation in patients with primary esophageal motility disorders are discussed in Part 4 (see Chapter 33). Medical and surgical issues related to GERD are the topic of this part and are summarized in the Overview (see Chapter 37). This chapter focuses on surgical instrumentation and techniques for the less common or complex benign esophageal stricture.

Dysphagia is the cardinal symptom of esophageal stricture. In most cases, when a stricture is suspected, the patient is evaluated radiographically with a barium swallow. The goals of this imaging modality are to establish the location, length, and number of strictures; to determine the maximal or minimal luminal diameter in normal and strictured regions; and to identify the presence of associated pathologies, such as esophageal diverticula, including Zenker diverticula, or hiatal hernia. This information is helpful for selecting instrumentation, devising strategies for treatment, estimating the number of sessions that will be required to relieve the patient's symptoms, and counseling patients about the expected risks of dilation. If barium studies raise suspicion for malignancy, a diagnostic endoscopy may be required. Usually, however, endoscopy and dilation are combined in the initial session.

In addition to specific features of esophageal stricture that contraindicate dilation (e.g., extremely long and tortuous strictures), several comorbidities also can increase the patient's risk. Dilation should not be attempted in the setting of an acute or incompletely healed esophageal perforation. As with any other surgical procedure, the benefits of esophageal dilation should outweigh the risks of the procedure in all patients with bleeding disorders or severe pulmonary or cardiovascular disease. Such patients may not tolerate endoscopy, with or without dilation. Dilation should be performed cautiously in patients with a pharyngeal or cervical deformity, recent surgery, a large thoracic aneurysm, or an impacted food bolus.

There are two basic types of dilators, mechanical and balloon, and each may be fitted with a guidewire (Figs. 44-1 and 44-2). Studies comparing mechanical (bougie) and balloon dilation have reported varying results.^5,6 The success of one instrument over the other depends largely on the endoscopist's experience and familiarity with a particular product. However, for strictures with complex features, a guidewire-based mechanical or balloon dilating system, such as the Savary esophageal dilator (Wilson-Cook Medical, Inc., Winston-Salem, NC), should be used exclusively. The mechanics of esophageal luminal dilation are not known precisely, but the results probably are affected by circumferential stretching or frank splitting of the stricture. Mechanical and balloon dilators differ in the way they accomplish this goal. Mechanical dilators exert a longitudinal and radial force, dilating progressively from the proximal to the distal extent of the stricture. In contrast, balloon dilators deliver the force radially and uniformly across the entire length of the stricture, which significantly reduces shear stress.

Mechanical Dilators

Mechanical dilators are classified as those that can be passed freely through the stricture and those that are inserted over a guidewire. The Maloney dilator (Medovations, Inc., Germantown, WI) is the most commonly used freehand dilator.⁵ Maloney dilators have a tapered heavy tip and come in multiple sizes. Several versions of guidewire-assisted dilators are available, but the Savary-Gilliard device (Wilson-Cook, Inc., Winston-Salem, NC) is probably used most commonly. This dilator is made from plastic, has a tapered tip, and comes in multiple sizes. Bard Interventional Products, Inc. (Tewksbury, MA), has a similar product called the American Dilatation System. An older system, the Eder-Puestow Olive dilators (Eder Instruments Co., Chicago, IL), uses progressively larger elliptical metal dilators that are passed over a guidewire. We prefer the Savary dilators for their flexibility and ease of use in our practice, and these generally have supplanted the metal Olive dilators.

Balloon Dilators

The first variety of balloon devices is the through-the-scope balloon dilator (multiple manufacturers), which is passed directly through the biopsy channel of the endoscope. The other variety is the over-the-guidewire balloon dilator (Boston Scientific Corp., Natick, MA). Compared with predecessor models, the newer balloons are capable of exerting greater radial forces and more predictably attaining maximum diameter on expansion.

Simple esophageal strictures typically are related to prolonged reflux esophagitis (i.e., peptic strictures). These strictures have a smooth surface and are short and straight. They are usually located in the distal esophagus and are large enough to be traversed with the endoscope (i.e., stricture diameter is more than 10 mm). In such cases, it is usually unnecessary to resort to a guidewire or balloon system. A freely passed dilator, such as the Maloney dilator, can readily accomplish effective and safe dilation in a simple esophageal stricture.

Strictures that are long, narrow, or tortuous or strictures associated with other pathologies such as a large hiatal hernia, esophageal diverticula, or tracheoesophageal fistula are better managed with a guidewire- or balloon-based system. Attempting to maneuver a freely passed dilator through a tortuous or anomalous esophagus can be problematic because the tip may fail to enter the stomach or may even perforate the esophagus.

Esophageal dilation typically is performed in an outpatient (ambulatory) facility using conscious sedation and topical pharyngeal anesthesia or general anesthesia. Some patients requiring multiple dilations may tolerate the procedure well without sedation. Patients who require frequent dilations even may be given Maloney dilators to take home for self-dilation. Patients are required to fast before dilation to ensure a clear view of the esophageal lumen and prevent aspiration. Patients should be instructed to avoid antiplatelet agents (e.g., aspirin) for 5 to 7 days before the procedure. Antibiotic prophylaxis is given to patients at high risk for bacterial endocarditis. Choice of the initial dilator size is based on the stricture diameter, which can be estimated during radiography or by comparing the stricture to the outer diameter of the endoscope. Dilation usually is performed in the supine position in the sleeping patient or in the decubitus position in the awake patient.

Use of Fluoroscopy

Dilation can be performed without endoscopy, during endoscopy alone, during endoscopy aided by fluoroscopy, or with fluoroscopic guidance alone depending on the clinical circumstances and preference of the endoscopist. As an example, some endoscopists routinely use fluoroscopy when passing a guidewire through a narrow stricture. Others will pass a guidewire through the stricture during endoscopy without fluoroscopy if the patient has undergone prior endoscopy or the passage into the stomach is clear. This would not be recommended when there is a high index of suspicion for unexpected pathology or anatomic variation distal to the view of the endoscope.

Number of Dilators per Session

It is a generally accepted rule that no more than three dilators of progressively increasing diameter should be passed in a single session and that the luminal stenosis should be increased by no more than 2 mm (6F). One or two dilators, at most, are recommended for very tight or very long strictures. These general principles help to reduce the likelihood of adverse sequelae that can arise from overexuberant dilation.

Repeated Sessions

The frequency of repeated dilation sessions depends on the success of initial dilation and the patient's past response to dilation. Patients undergoing esophageal dilation for the first time may require multiple sessions, especially if the stricture has a narrow diameter and exhibits significant resistance during dilation. Such patients may require repeated sessions every 5 to 7 days. After sufficient progress has been achieved, less frequent sessions may be satisfactory. In some patients, however, symptoms tend to recur rapidly after dilation. Such patients require more frequent dilations based on symptoms.

Through-the-Scope Balloon Dilation

Prospective comparisons of through-the-scope balloon dilators with mechanical dilators suggest that they are equally safe for dilating esophageal strictures. In addition, one study suggested that stricture recurrence may be less during the second year after through-the-scope compared with mechanical dilation. Through-the-scope balloon dilators are passed through the channel of the endoscope into the stricture under direct vision or during fluoroscopy. To prevent proximal migration of the balloon during inflation, the endoscope should be positioned just behind the proximal end of the balloon while holding the balloon sheath tightly. The optimal number and duration of inflations have not been established. Most endoscopists perform two dilations of 30 to 60 seconds duration in each session.

The size of the lumen after dilation is directly related to the level of symptom relief the patient experiences and the need for recurrent dilation. Although there is no firm or fast rule, in our experience, a luminal diameter of 18 mm (54F) generally is sufficient for normal swallowing and permits intake of a regular diet unless there is a coexisting motility disturbance. Patients with an esophageal lumen of less than 13 mm in diameter (39F) usually will experience dysphagia to solid foods. Some strictures are more difficult to dilate, and such patients may have to accept less than optimal results. Patients dilated to a diameter of 15 mm (45F), for example, are still able to eat a regular, if modified, diet but should be instructed to eat slowly and chew their food well.

Esophageal perforation is the major and most dreaded complication of esophageal dilation. The incidence of perforation is influenced by the etiology of the stricture and factors related to technique, operator experience, and equipment. Several risk factors for esophageal perforation have been recognized, although the magnitude of risk is uncertain. These factors include malignant stricture, severe esophagitis, prior radiation therapy, history of caustic ingestion, eosinophilic esophagitis, complex (tortuous) or long strictures, presence of esophageal diverticulum, inexperienced operator, large hiatal hernia, use of high inflation pressures with balloon dilation, and a history of previous esophageal perforation or prior esophageal surgery, such as for trauma or a congenital abnormality. (Techniques for the management of esophageal perforation are described in Chapter 48.)

Bacteremia

Esophageal dilation has the highest incidence of bacteremia of all gastrointestinal endoscopic procedures. Nonetheless, complications of bacteremia, such as endocarditis, are rare. Antibiotic prophylaxis is not warranted in most patients undergoing esophageal dilation except for those with a recognized risk for endocarditis.

Chest Pain

Chest pain is sometimes observed after stricture dilation. It is usually mild, self-limited, and requires no specific therapy. Rare patients require a period of a liquid diet and analgesics. However, the development of chest pain (or any signs of clinical deterioration) can signal the development of a perforation. If there is any concern for impending perforation, a water-soluble contrast study should be obtained before discharge. Such patients also may require hospitalization and observation for brief periods, during which the patient should be maintained nothing by mouth.

Hemorrhage

Significant hemorrhage related to esophageal dilation is uncommon except when the patient is anticoagulated. Recent experience suggests that when hemorrhage occurs, it is unrelated to the type of dilator used. Appropriate measures should be taken to prevent bleeding in patients taking medications that affect their coagulation status or platelet function.

Miscellaneous Complications

Other complications of esophageal dilation are related mostly to conscious sedation and endoscopy and include aspiration pneumonia, respiratory failure, and cardiac arrhythmias.

Increasing experience suggests that temporarily placed nonmetal expandable stents can be effective for the management of benign strictures that are refractory to dilation by other current systems. One such silicone-coated stent (Polyflex stent, Rusch International, distributed by Boston Scientific Corporation, Natick, MA) has been approved for use in patients. Clinical experience with this stent in benign strictures has suggested a problem with stent migration.

The general incidence of complications with expandable metal stents is also high, including migration, stent-induced trauma leading to perforation, and tracheoesophageal fistula.⁷ Furthermore, approximately 40% of patients have experienced stent-induced stenosis caused by granulation tissue and fibrosis. Consequently, we do not recommend expandable metal stents for benign esophageal strictures in our clinical practice unless they are placed for a limited time only. Other nonmetal stents continue to be developed. A prototype biodegradable esophageal stent made from a coil of poly-l-lactide (Instent, Inc., Eden Praire, MN) has been used in a patient with benign refractory stricture after radiation therapy. This patient experienced short-term relief of dysphagia.

Surgical options should be discussed with young patients with peptic strictures who require frequent dilations or who depend on chronic proton pump inhibitor therapy. An antireflux operation is applicable when the stricture cannot be dilated adequately. With significant shortening of the esophagus, a Collis gastroplasty (see Chapter 38) combined with fundoplication is more likely to give a satisfactory result. Resection naturally should be reserved for patients whose strictures cannot be dilated adequately or in whom simpler procedures have failed.³ The options for restoring continuity of the esophagus after resection include esophagogastrostomy, colon interposition, and jejunal interposition (see Chapter 33).

Patients with proximal strictures related to previous surgery or radiation therapy for head and neck tumors present a special surgical challenge. The proximal nature of these strictures, on occasion, makes them difficult to access via standard endoscopy. We have previously reported a novel approach for dilation of these strictures.⁸ The stomach is accessed endoscopically through a gastrostomy site, which is usually present for feeding, and the endoscope is advanced retrogradely into the esophagus under fluoroscopic guidance until the stricture is visualized from below and cannulated with the guidewire. The guidewire is advanced, pulled out from the mouth, and used to advance Savary dilators in the antegrade direction.

Although dysphagia is the cardinal symptom of esophageal stricture, it should prompt one to look for other causative pathologies, such as GERD, primary esophageal motility disturbances, infection, malignancy, and esophageal webs or rings. Although treatment of some of these conditions may involve esophageal dilation, the techniques differ, requiring accurate diagnosis and appropriate treatment planning before embarking on the procedure.

The dilatation of a known esophageal carcinoma is more hazardous than that of a benign stricture. A perforation may upstage the patient's cancer and mandate an emergent esophagectomy. Therefore, I prefer to stent patients with obstruction related to carcinoma or provide them with a jejunostomy tube during neoadjuvant therapy.

When sequentially dilating a patient's stricture, I recommend stopping as soon as blood appears on the stent. It is also wise to finish every dilatation procedure by performing a final endoscopy to make sure there is no perforation.