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Ann Thorac Surg 1997;63:209-213
© 1997 The Society of Thoracic Surgeons

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Original Articles: General Thoracic

Tracheal Wire Stent Complications in Malacia: Implications of Position and Design

Department of Cardiothoracic Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin

Accepted for publication August 14, 1996.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Patient 1 Patient 2 Patient 3 Comment References

 
Background. Although expandable endoluminal wire stents that can be incorporated into body tissues are very attractive for use in the airway, disease-related factors that can lead to stent failure have received little attention in the literature.

Methods. The cases of all 4 patients who underwent insertion of one or more Gianturco stents into the trachea, main bronchi, or both for tracheobronchial malacia in our institution were reviewed.

Results. All three tracheal stents required removal for stent-related complications within the first 6 months. Complications included metallic strut fracture and unraveling or breakage of the encircling nylon suture leading to progressively bizarre and widening radiographic configurations suggesting imminent airway perforation. One of the six bronchial stents disrupted 10 months after insertion.

Conclusions. Our findings suggest relatively less dynamic, repetitive bending wire stress in the bronchus (and likewise strictured trachea) compared with the malacic trachea. Although Gianturco stents are easily placed and give excellent functional results, we recommend against their use in the trachea for tracheal malacia. The bronchial position may be reasonably safe.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Patient 1 Patient 2 Patient 3 Comment References

 
See also page 213.

Previous reports of complications caused by the placement of expandable wire stents in the tracheobronchial tree have not addressed differences between anatomic regions of the airway or disease etiology as predisposing factors to stent complication. Both self-expandable Gianturco (Cook Cardiology, Bloomington, IN) and Wall (Schneider USA, Inc, Minneapolis, MN) stents have demonstrated usefulness for the management of airway strictures and tracheobronchial malacia. Although these wire stents are highly desirable because they can be incorporated into tissue with less bronchial obstruction or mucous pluggings, a number of complications necessitating further manipulation or stent removal have been described. These include malposition, migration, perforation, esophageal impingement, unraveling, excessive granulation, and hemorrhage [1–4]. Details of these occurrences as they apply to stent design are uncertain.

The dynamic characteristics of the fibrotic, narrowed airway are completely different from those of the airway affected by tracheomalacia. In addition, the mucosal features at points of stent contact can be different in a fibrotic segment compared with a malacic segment, and granulation tissue can grow differently. Compared with a relatively fixed stricture, the malacic trachea has tremendous variation in shape and diameter during the respiratory cycle and coughing. Forces acting on the stent are, therefore, very different, and these differences may affect longevity of the stent. This report describes our experience with Gianturco stents inserted for tracheobronchial malacia with expiratory airway collapse.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Patient 1 Patient 2 Patient 3 Comment References

 
Gianturco stents are constructed in a single or tandem arrangement of cylindrically fashioned stainless steel wires. The cylindric shape is created by an encircling 4-0 nylon suture laced through eyelets at the terminal aspects and joining the tandem stents. Outward-protruding hooks incorporated into the structure of the wire were added by designers to inhibit migration after stent placement. The stents are released into the tracheobronchial lesion by deployment through a long catheter cartridge aided by fluoroscopic or direct bronchoscopic surveillance.

Gianturco stents were placed in 5 patients during the period March 1992 to June 1995. Four patients had tracheobronchial malacia, and 1 patient, the earliest in our experience with this stent, had a narrowed bronchus after single-lung transplantation. This patient had a well-incorporated, intact stent at postmortem examination 2 years after initial stent placement. One of the 4 patients with tracheobronchial malacia required only insertion of a left main bronchial Gianturco stent for localized left main bronchial expiratory collapse. The 3 remaining patients, who are the main subject of this report, received tracheal wire stents for tracheobronchial malacia resulting from chronic obstructive pulmonary disease. Two of these 3 patients also underwent simultaneous stent placement in both bronchi. All patients with malacia received stents within 2 months of each other, and subsequent stent complications also occurred fairly close together temporally, thus suggesting a common natural history.

	Patient 1

Top Footnotes Abstract Introduction Material and Methods Patient 1 Patient 2 Patient 3 Comment References

 
A 68-year-old man had progressive respiratory disability from chronic obstructive pulmonary disease–associated tracheobronchial malacia. Multiple Gianturco stents were placed: a double-body stent in the trachea and single stents in the left main, the right intermediate, and the middle lobe bronchi. The postoperative course was uneventful, and the patient quickly progressed to an activity level that was not possible prior to stent placement. Two months later, he described coughing up a 2.5-cm fragment of wire but waited several days before returning for medical care. Chest roentgenograms clearly demonstrated disruption of the tracheal stent (Fig 1). Although we informed the patient that the safest, most conservative mode of retrieval (and that recommended by the manufacturer) was by thoracotomy and tracheal incision, the patient so feared thoracotomy that we decided to attempt bronchoscopic removal.

View larger version (120K): [in this window] [in a new window]   Fig 1. . (Patient 1.) (A) Lateral chest roentgenogram demonstrating intact Gianturco stents in tracheal position and extending into bronchi. (B) Lateral chest roentgenogram demonstrating disrupted tracheal stent (upper portion of figure), marked widening of stent, and erratic angulation of remaining fragments. Note point of metallic fracture just proximal to hairpin curve of stent.

No evidence of hemorrhage or tracheal disruption was seen at bronchoscopy. The patient remained intubated for the next 24 hours because of airway edema. The postoperative chest roentgenogram demonstrated a small residual metallic piece, clearly part of the stent. Chest computed tomographic scan was performed the next morning to further localize this fragment, which appeared to be tucked in the collapsing right lateral aspect of the trachea.

Because of decreased edema, we were able to remove the wire fragment quite easily at repeat bronchoscopy. The patient was discharged home 3 days after this procedure with comfortable, functional breathing, although it was not as good as when the stent was in place. Initially his respiratory status was acceptable enough to him without stent replacement, but he subsequently required insertion of another stent (Wall stent) because of progressively worsening dyspnea. We used a Schneider-Wall stent, a small-meshed, smoother contoured self-expandable wire stent.

	Patient 2

Top Footnotes Abstract Introduction Material and Methods Patient 1 Patient 2 Patient 3 Comment References

 
A 70-year-old woman with disabling chronic obstructive pulmonary disease and diffuse tracheobronchial malacia because of expiratory airway collapse required continuous mechanical ventilation. During hospitalization for bronchopneumonia, she underwent tracheal and bronchial stent placement. Stents were placed in the trachea (double-body) and in the left main and right intermediate bronchi (single). She was soon extubated and discharged. She subsequently described two brief episodes of minor hemoptysis 5 and 6 months after placement of the wire stents. Two days after the second episode, roentgenograms showed that the tracheal stent had a metal fracture and a widened overall diameter. A computed tomographic scan suggested extramural migration by one of the broken wire fragments. An incidentally discovered growing right upper lobe nodule on the radiographs was suspected of being cancerous.

The patient underwent transbronchoscopic tracheal stent removal because of the changing configuration of the stent and the concern about perforation. Most of the stent was removed in two pieces using an identical rigid biopsy forceps and traction method as in patient 1. During spontaneous ventilation after stent removal, the trachea again demonstrated complete closure with exhalation, a situation mandating eventual stent replacement after the edema and inflammation subsided. Chest computed tomographic scan performed the next day demonstrated substantial tracheal enlargement and the exact location of two residual stent fragments not visualized during earlier direct examination (edema and tissue incorporation). One fragment appeared outside the tracheal lumen adjacent to an aberrant right subclavian artery.

Four days later, bronchoscopic examination failed to visualize the remaining fragments. Therefore, a right axillary thoracotomy was performed to expose the trachea and the right upper lobe adenocarcinoma. This tumor along with a large bullous area was removed by a wedge resection because of the prohibitively poor pulmonary reserve of the patient. Examination of the distal trachea revealed a stent fragment partially protruding through the full thickness of the tracheal wall adjacent to the aberrant subclavian artery. This fragment was easily removed from outside the trachea without tracheotomy or a large residual defect. The other fragment was deeply embedded in the wall, was not palpable, and was not sought further. The patient was then placed supine and underwent repeat tracheal stenting with two 20 x 55-mm Schneider-Wall stents, but this time they were positioned within one another in a partially overlapping pattern to incorporate the entire malacic trachea.

A bedside bronchoscopy was performed 2 days later and demonstrated slight proximal migration of the distal end of the new stent, revealing about 1 cm of trachea between this margin and the carina. Good overall patency during exhalation was noted. After extubation, the patient continued to have somewhat noisy respirations and a prolonged expiratory phase. Bronchoscopy 4 days after stent replacement confirmed some secretion accumulation along the stent surface but no further stent migration or obstruction. The bronchial stents have remained intact.

	Patient 3

Top Footnotes Abstract Introduction Material and Methods Patient 1 Patient 2 Patient 3 Comment References

 
A 76-year-old man with posttracheostomy tracheal malacia and multiple comorbid medical problems was transferred to our facility because of major dyspnea and wheezing. He had recently been discharged from an inpatient rehabilitation facility after a protracted hospital stay resulting from a motor vehicle accident (3 months previously). The severe closed cranial and cerebrovascular injuries incurred in the accident necessitated a tracheostomy. A proximal tracheal functional stricture associated with malacia developed, which we treated by placement of a double-body Gianturco stent across the malacic area. Four months later, the patient was seen again with dyspnea and underwent bronchoscopic debridement of granulation tissue that had built up within and around the stent. Over the next 2 months, he did not have recurrent obstructive symptoms, but there was widening of the upper end of the wire stent and trachea suggesting disruption of the encircling 4-0 nylon suture. Because of concern about potential erosion into the esophagus or innominate artery, the patient underwent endoscopic stent removal. He was extubated the following day, demonstrated no persistent obstructive respiratory symptoms, and was discharged after a 3-day hospital stay.

	Comment

Top Footnotes Abstract Introduction Material and Methods Patient 1 Patient 2 Patient 3 Comment References

 
Loss of expandable wire stent continuity is uncommon overall but has been described in vascular, biliary, and tracheobronchial positions. With a prototype of the expandable wire stent available today, Wallace and associates [1] demonstrated a high incidence of migration (87%) and esophageal impingement (100%), but these stents were oversized and lacked anchors. No stent fractures occurred after 8 weeks in the dogs studied.

Nashef and co-workers [2] used 28 single- and double-body Gianturco tracheobronchial stents with anchoring barbs in 15 patients. Five of the patients were treated for tracheobronchial malacia with "good' results in 3, but all 3 required laser or coagulation removal of granulomas. Two malacic patients had stent complications including suction catheter entrapment and pulmonary artery erosion from stenting over a necrotic bronchus. Among the entire group of 15 patients, wire fractures were removed by rigid bronchoscopy. Their extraction technique, which the authors likened to "rolling spaghetti on a fork', includes fracturing (by laser or mechanically) the stent, rotation and unraveling, and piecemeal removal.

Rousseau and colleagues [3] described a 31% complication rate in 35 Gianturco stents placed in 19 patients with tracheobronchial malacia. These complications were principally migration and fracture leading to obstruction and wall perforation. Two stents were removed, and another patient died of consequent respiratory distress.

In 1994, Carrasco and coauthors [4] described 17 complications in 15 patients after reviewing 36 patients treated with Gianturco stents for malignant stenoses. Two stents in 2 patients unraveled when a stiff section catheter became caught in the stent, a complication contributing to the death of 1 of the patients. Another stent fractured 3 months after insertion with no untoward effects. These authors recommend soft suction catheters and caution against stent extraction.

The current collective experience with Gianturco stents in patients with tracheobronchial malacia demonstrates a prohibitive risk of fracture or dysfunction. The issues related to this experience include causes of wire fracture in malacia, need and method of stent removal, requirement of stent replacement after removal, and optimal malacic-airway stent options.

Loss of tracheal stent continuity in our experience was due to wire fracture (2 patients) and rupture of the encircling suture (1 patient). The malacic trachea has an overall increased luminal diameter and wider excursions, including complete expiratory collapse, than the narrowed stenotic trachea or malacic bronchus. These can lead to increased stretch on encircling nylon sutures and metal fatigue from repetitive, stereotypic movements. Also, single-body struts, without shared suture between stents, were more frequently used in the bronchial position. Other factors that can lead to wire stent disruption include iatrogenic injuries from a firm suction catheter [4] and other trauma, especially grasping repositioning maneuvers, which create metal weakness. Fractures in our series all occurred at natural bends in the stents.

Carrasco and associates [4] advise against removal of Gianturco stents. In contrast, Rousseau and colleagues [3] described important morbidity and mortality associated with loss of stent continuity. We agree with Rousseau and colleagues because of potential laceration or erosion of the airway and neighboring mediastinal structures and recommend rigid and flexible bronchoscopic removal of all fractured stents (wire limb or nylon suture) or stents with an exaggeratedly expanding diameter (sentinal sign of impending rupture).

Our removal technique includes general anesthesia, jet ventilator, and no paralysis in the operating room. The stents were extracted, often in two to four unraveled fragments, by controlled, steady traction with alligator biopsy forceps. We do not have experience with laser division of the wire as described by some authors and could not find a sufficiently long scissors instrument. In two instances, a small fragment remained after initial removal. In 1 patient, it was successfully removed by rigid bronchoscopy, and the other patient underwent removal of a full-thickness penetrating fragment (as well as resection of a carcinoma) by thoracotomy. Endotracheal-tube airway protection was used in all patients for 24 hours after stent removal because of concern about airway edema and potential hemorrhage. All patients were then extubated with comfortable respirations.

One patient required tracheal stent replacement (Wall stent) during the same admission because of total airway collapse with spontaneous exhalation. The other 2 patients demonstrated adequate breathing ability initially, but after a few months, they also required tracheal stent replacement for progressive dyspnea.

Although the symptomatology of severe chronic obstructive pulmonary disease includes small-airway disease, alveolar destruction, and abnormal chest wall mechanics, there is a smaller subgrouping of COPD and other diseases with severe tracheobronchial malacia that causes mechanical expiratory obstruction to air flow and secretions. The components of end-expiratory collapse and consequent poor clearance of secretions may be palliated with airway patency from intraluminal stenting. This therapy is routinely tested objectively as well as subjectively. To date, there are no perfect stents for all diseases and positions.

We discontinued the use of wire stents in the Gianturco wide zigzag design and chose the Wallstent as our initial alternative tracheal stent. We thought that the fine metallic mesh design would be less prone to stretching and repetitive stress, but we have also observed wire fragmentation in a malacic trachea supported by these stents. Silicone elastomer stents also have the drawbacks of decreased airway diameter, migration, and mucous clogging. We do not have experience with other reported airway stents including Palmaz (Johnson & Johnson Interventional Systems, Warren, NJ) and covered wire stents [5]. We anticipate that design modifications will lead to a more optimal and safe wire stent for the malacic tracheal airway.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Patient 1 Patient 2 Patient 3 Comment References

 
Address reprint requests to Dr. Haasler, Department of Cardiothoracic Surgery, Medical College of Wisconsin, Froedtert Memorial Lutheran Hospital, PO Box 26099, Milwaukee, WI 53226–0099.

	References

Top Footnotes Abstract Introduction Material and Methods Patient 1 Patient 2 Patient 3 Comment References

 

1. Wallace MJ, Charnsangavej C, Ogawa K, et al. Tracheobronchial tree: expandable metallic stents used in experimental and clinical applications, work in progress. Radiology 1986;158:309–12.
2. Nashef SAM, Dromer C, Velly J-F, Labrousse L, Couraud L. Expanding wire stents in benign tracheobronchial disease: indications and complications. Ann Thorac Surg 1992;54:937–40.[Abstract]
3. Rousseau H, Dahan M, Lauque D, et al. Self-expandable prostheses in the tracheobronchial tree. Radiology 1993;188:199–203.[Abstract/Free Full Text]
4. Carrasco CH, Nesbitt JC, Charnsangavej C, et al. Management of tracheal and bronchial stenoses with the Gianturco stent. Ann Thorac Surg 1994;58:1012–7.
5. Gaissert HA, Patterson GA. Tracheobronchial stents. In: Pearson FG, Deslauriers J, Ginsberg RJ, Hiebert CA, McKneally MF, Urschel HC Jr, eds. Thoracic surgery. New York: Churchill Livingstone, 1995:223–33.

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): John E. Hramiec George B. Haasler Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hramiec, J. E. Articles by Haasler, G. B. Search for Related Content PubMed PubMed Citation Articles by Hramiec, J. E. Articles by Haasler, G. B. Related Collections Related Article