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Successful Transcatheter Management of Palmaz Stent Embolization After Superior Vena Cava Stenting

Antonio L. Bartorelli, MD, Franco Fabbiocchi, MD, Piero Montorsi, MD, Alessandro Loaldi, MD, Gloria Tamborini, MD, and Paolo Sganzerla, MD

Introduction

Metallic balloon-expandable stents have been used as an attractive and successful alternative approach for the treatment of superior vena cava syndrome (SVCS) [ 1-51. This article illustrates a case of benign SVCS that was treated with implantation of tandem Palmaz peripheral stents and was complicated by embolization of one stent to the right atrium. This unexpected complication was successfully managed using a percutaneous transcatheter technique.

Case report

A 34-year-old man with a 3-month history of progressively worsening facial swelling was admitted to another hospital. Chest X-ray examination was normal. Computed tomography and magnetic resonance scans showed a normal mediastinum. Cavography revealed stenosis of the superior vena cava (SVC) just below the innominate vein junction (Fig. 1A). Left thoracotomy was performed to relieve the obstruction but failed because of bleeding and inability to remove the dense scar tissue entrapping the SVC. A diagnosis of idiopathic fibrosing mediastinitis was made on the basis of negative mediastinal biopsy and serologic tests for histoplasmosis [6]. The day after operation, the patient had acute onset of dyspnea and severe upper body edema that were only partially reduced by diuretic and steroid therapy. Following discharge, the patient’s symptoms progressed in severity despite medical treatment and 1 month later he was admitted to our institution. Clinical examination rerevealed a regular pulse rate of 100 bpm, with a blood pressure of 120/80 mm Hg. The jugular veins were grossly distended, and prominent veins over the chest and upper abdomen were noticed in association with facial congestion and skin telangiectasia of the upper trunk. Bilateral arm venography revealed complete SVC obstruction associated with massive thrombosis of left and right innominate and subclavian veins (Fig. 1B).

Interventional procedure

Thrombolytic Therapy

The patient received 10,000 units of heparin i.v. and 2 million units of urokinase administered during a 10-hr period via two 5-F infusion catheters placed bilaterally through the basilic veins and embedded with their tips into the thrombus occluding the innominate veins. Control venography demonstrated partial resolution of thrombi and persistence of complete SVC obstruction.

Angioplasty and Stent Implantation

Via a percutaneous right femoral venous approach, the SVC occlusion was traversed with a 0.035 inch straight guidewire and dilated with a Penta I1 10 mm X 4 cm balloon catheter (Boston Scientific Corp., Watertown, MA). A repeat cavogram showed restoration of rapid flow into the right atrium and severe residual SVC narrowing (Fig. 2). Because the stenosis immediately recurred despite multiple redilations, placement of two 12-mm Palmaz peripheral stents (Johnson & Johnson Interventional Systems, Warren, NJ) was planned. The first stent was deployed just below the innominate vein junction with a Penta I1 10 mm X 4 cm balloon catheter (Boston Scientific Corp., Watertown, MA) positioned across the stenosis and inflated to 6 atm of pressure. The second stent was placed in tandem following the same procedure. Subsequently, both stents were further dilated with a Penta I1 12 mm X 4 cm balloon catheter (Boston Scientific Corp., Watertown, MA) inflated at 9 atm to further expand them and to achieve good fixation to SVC wall. Nevertheless, 10 min later the caudal stent embolized into the right atrium. Fortunately, the guidewire left in position across the stents prevented the lost stent from migrating to the right ventricle and pulmonary artery.

Fig. 1.
Digital subtraction superior vena cavogram. A: Severe stenosis of the superior vena cava (arrow) just below the junction of the innominate veins. B: Total occlusion of superior vena cava with retrograde bilateral thrombosis of innominate and subclavian (SV) veins. Note extensive collateral venous circulation (arrows).

Complication Management

A transcatheter approach to manage this complication was undertaken as follows. A Cribier-Letac 15 mm X 5.5 cm aortic valvuloplasty catheter (Boston Scientific Corp., Watertown, MA) was advanced over the guidewire into the right atrium and across the lost stent. The stent, clearly visible under fluoroscopy, was captured inflating the balloon at low pressure. Under fluoroscopic guidance, the balloon-stent assembly was then withdrawn through the inferior vena cava and into the right external iliac vein where the stent was successfully deployed increasing the balloon pressure to 9 atm (Fig. 3). Post-procedural cavogram demonstrated excellent flow through SVC, which showed a 12-mm diameter at its previous stenotic site (Fig. 4). After SVC stenting, the patient’s symptoms were rapidly reduced and completely resolved within 24 hr. Oral anticoagulant therapy was started and he was discharged 5 days after the procedure.

Fig. 2.
Digital sL-traction superior vena cavogram showing severe residual stenosis of superior vena cava (arrow) after balloon angioplasty.

Fig. 3.
Plain radiograph of the pelvis showing the Palmaz stent (arrow) implanted into the right external iliac vein. Note the wire across the stent and the opacified ureter on its left.

Follow-up

Eight months following stent placement the patient was asymptomatic at rest and complained of a mild sensation of neck fullness upon strenuous exercise. Venography evidenced unobstructed flow through the stented right external iliac vein (Fig. 5) and moderate restenosis of the most cephalic end of SVC stent (Fig. 6) that was successfully redilated. At 12-month clinical follow-up, he continues to be asymptomatic even during stressful physical activity.

Discussion

Although conventional balloon angioplasty has shown to be successful in dilating SVC obstructions [7-lo], unsatisfactory short-term results and recurrence are frequently reported. As in this case, elastic recoil and extrinsic compression of the SVC are often the cause of stenosis recurrence immediately upon balloon deflation.

Since 1986 more than 70 patients with SVCS have been treated with metallic stents, which, acting as scaffolds with expansile strength, eliminated elastic recoil and achieved good results. Although Palmaz stents have been successfully employed, the largest experience has been accumulated with another balloon-expandable design, the Gianturco-Rosch Z-stent [I-51. In most cases this non-surgical alternative was successfully used to obtain symptomatic palliation in patients with malignancy and a life expectancy of weeks or months. On the other hand, caution has been recommended with stenting of benign SVC obstruction because long-term effects of permanent intravenous stent implantation are unknown [5]. Reviewing the medical literature, we found only few patients in whom Gianturco stents were placed for treatment of benign SVC obstructions uncomplicated by secondary thrombosis [4,5]. In spite of this modest experience, we considered this treatment justified in our patient because of previous surgical failure, lack of alternative therapy, and immediate stenosis recurrence after balloon angioplasty .

A potential procedural complication of SVC stenting is stent dislodgement followed by embolization. This event may have deleterious clinical effects. A lost stent may act as a nidus for thrombus deposition with subsequent pulmonary embolism. In addition, migration into the right ventricle may cause arrhythmias. Embolization following SVC stenting has been observed in one case with an early Gianturco stent design [ 11. Subsequently, the design was modified with the addition of anchoring barbs to the stent body [3]. The embolization observed in our case, to our knowledge never described before following Palmaz stent implantation in the SVC, was probably due to a combination of factors. The Palmaz design has no barbs to prevent migration, and the stent is held in place by strut encasement into the vessel wall. In our patient, the cranial stent covered the stenotic region almost entirely, while the caudal stent was inadvertently deployed across a nearly normal and pliable SVC segment. Consequently, this venous segment exerted only light extrinsic compression on the intraluminal prosthesis, precluding firm fixation.

Since the embolized stent was already fully expanded at a diameter of 12 mm, we could not use previously described methods for non-surgical retrieval of intracardiac foreign bodies and undeployed stents lost in the coronary arteries or in the systemic circulation [ll-151. In fact, even in the case of successful capture of the embolized stent by means of a retrieval device, it would have been very difficult to considerably reduce its dimensions. Therefore, an attempt at transcatheter removal from the venous circulation could have beeen associated with serious damage to the iliac and femoral veins. On the other hand, surgical retrieval would have involved a major operation. Therefore, we decided to manage this complication with a simple percutaneous approach, using a valvuloplasty catheter to capture the stent lost into the right atrium and to deploy it in the right external iliac vein. There is no doubt that the guidewire left across the stented SVC prevented the lost stent from migrating to the right ventricle or pulmonary artery and enabled us to retrieve it. Therefore, its use seems an important safety procedure with this type of intervention as suggested by Salomon et al. and confirmed by this case [2].

Although further experience will be required, use of metallic stents seems promising as the primary and definitive approach to relieve benign SVC obstruction when medical treatment has failed. However, the probability of experiencing stent loss will increase as this treatment modality expands. The transcatheter management described herein may represent a useful and safe technique to reduce clinical risks and avoid surgical intervention should this type of complication occur after Palmaz stent implantation in the SVC.

Fig. 4.
Digital subtraction superior vena cavogram showing final result after Palmaz stent placement.

Fig. 5.
Eight-month follow-up angiography demonstrating unobstructed flow through the stent implanted into the right external iliac vein (arrow). The filling defect above the stent is due to contrast dilution and turbolence caused by blood coming from the right internal iliac vein.

Fig. 6.
Digital subtraction superior vena cavogram at 8 months showing moderate restenosis of the most cephalic end of the SVC stent.

 

References

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Autor: Antonio L. Bartorelli, MD, Franco Fabbiocchi, MD, Piero Montorsi, MD, Alessandro Loaldi, MD, Gloria Tamborini, MD, and Paolo Sganzerla, MD

Fuente: Catheterization and Cardiovascular Diagnosis 34:162-166

Ultima actualizacion: 14 DE FEBRERO DE 2008

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