Ann Thorac Surg 2006;81:1872-1875
© 2006 The Society of Thoracic Surgeons
Case report
Emergency Endovascular Deployment of Stent Graft in the Ascending Aorta for Contained Rupture of Innominate Artery Pseudoaneurysm in a Pediatric Patient
Wilson Y. Szeto, MD
a
,
Ronald M. Fairman, MD
b
,
Michael A. Acker, MD
a
,
Christopher L. Skelly, MD
b
,
John G.T. Augoustides, MD
c
,
Michael McGarvey, MD
d
,
Edward Y. Woo, MD
b
,
Omaida C. Velazquez, MD
b
,
*
a Division of Cardiothoracic Surgery, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
b Division of Vascular Surgery, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
c Department of Anesthesia, University of Pennsylvania, Philadelphia, Pennsylvania
d Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania
Accepted for publication July 13, 2005.
* Address correspondence to Dr Velazquez, Department of Surgery, Hospital of Unversity of Pennsylvania, 3400 Spruce St, Fl Silverstein, Philadelphia, PA 19104 (Email: omaida.velazquez{at}uphs.upenn.edu).
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Abstract
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Endovascular approaches to treat aortic diseases have become an important alternative to open surgical intervention in aortic pathologies. We report a case of an emergency placement of a stent graft in a 16-year-old boy with a contained rupture of an innominate artery pseudoaneurysm. This patient had been previously treated for a mediastinal T-cell lymphoma and underwent mediastinal chemoradiation. He developed tracheal stenosis, requiring multiple tracheal reconstructive surgical procedures, and subsequently emergency ligation of a tracheal-innominate fistula. A pseudoaneurysm of the previously ligated innominate artery developed. Despite coil embolization, it continued to enlarge, requiring emergency endovascular intervention. A pseudoaneurysm of the previously ligated innominate artery subsequently developed, and despite coil embolization, it continued to enlarge, which required emergency endovascular intervention.
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Introduction
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Since the initial report of thoracic aortic stent grafts [1], endovascular repair of aortic aneurysm has become an acceptable surgical alternative to conventional repair [2–5]. With encouraging results, this technology is being evaluated for other diseases of the aorta including dissection, rupture, and traumatic transection. Because conventional approaches for aortic diseases in the emergency setting is associated with a significant risk of morbidity and mortality [6], emergency use of endovascular technologies has been utilized as an alternative therapeutic option in selected clinical situations [7–9]. Initial experiences with emergency use of stent grafts in the thoracic aorta have been reported with cautious enthusiasm [10, 11]. We report a case of endovascular treatment for an innominate artery pseudoaneurysm presenting acutely with a contained rupture in a pediatric patient otherwise not considered to be a candidate for conventional surgical options.
A 16-year-old boy presented to the emergency room with bleeding and an expanding pulsatile mass at his mediastinal tracheostomy site that resulted in a compromised airway and respiratory distress. The boy had a history of mediastinal T-cell lymphoma at the age of 14 years and had subsequently undergone chemotherapy with mediastinal irradiation. Since chemoradiation, he developed tracheal stenosis, requiring multiple tracheostomies and complex reconstructive airway surgeries. In March 2004 he presented with a tracheal-innominate fistula requiring emergency open surgical repair by proximal and distal ligation of the innominate artery and repair of the trachea with a pedicle pericardial flap. He maintained retrograde perfusion of the right common carotid artery and right subclavian artery, and initially he recovered well without neurologic incident. Subsequently the airway reconstruction broke down requiring a pectoralis flap first, and then eventually the creation of a mediastinal tracheostomy with omental flap. In October 2004 he had a contained pseudoaneurysm develop at the site of the previously ligated proximal stump of the innominate artery. Attempts to coil embolize the neck and the central cavity of the pseudoaneurysm were initially successful and were subsequently repeated twice for recurrence of flow (Fig 1). However, by December 2004, he presented with bleeding and an expanding pulsatile mass at his mediastinal tracheostomy with airway compromise. There were externally visible coils partially extruding into the airway at the head of a visibly tense, pulsatile upper mediastinal mass. Angiography confirmed re-expansion of the pseudoaneurysm with open flow from the aortic arch and dispersion of the coils into the periphery of the pseudoaneurysm cavity (Fig 2).
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Fig 1. Angiogram demonstrating previously ligated innominate artery with coil embolization of the pseudoaneurysm.
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Fig 2. Angiogram demonstrating contained rupture (pseudoaneurysm; see arrow) of the ligated innominate artery with dispersion of coils.
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Due to the complex anatomy and history of multiple surgical procedures in the mediastinum, the patient was not a candidate for open surgical intervention secondary to the high risk for intraoperative exsanguination. Endovascular placement of a stent graft was proposed as an option. With the patient and the family's consent, we proceeded with emergency endovascular treatment. A Zenith iliac limb extension from Cook (Bloomington, IN), commercially available for the treatment of abdominal aortic aneurysms, was utilized as the stent graft to exclude the innominate artery origin from the ascending aorta. The endograft was oversized by approximately 10% to the diameter of the patient's ascending aorta.
The first goal of our operative strategy was to safely control the patient's airway. Coils from previous embolization were eroding through the pseudoaneurysm at the mediastinal tracheostomy and conveyed the tenuous nature of his airway. It was believed that any attempt to manipulate and intubate the airway may result in free rupture of the pseudoaneurysm and exsanguination. Therefore, with local anesthesia, the right femoral artery and vein were dissected and cannulated with a 16-French and an 18-French cannula, respectively, in preparation for cardiopulmonary bypass. Heparin was administered and after cardiopulmonary bypass was instituted the patient was placed under intravenous general anesthesia. The surgical field was prepped and draped, and electroencephalogram leads were placed on the scalp. Our protocol of intraoperative neuromonitoring has been previously described in detail [12]. A diagnostic angiogram through the left femoral artery was performed and confirmed the presence of a contained rupture at the previously ligated proximal innominate artery.
The second goal of our operative strategy was to obliterate flow into the pseudoaneurysm by placing a stent graft across the innominate artery stump. With the innominate artery previously ligated and only retrograde flow into the right common carotid artery, it was essential that the stent graft did not compromise flow in the left common carotid artery. With a supraclavicular incision, a subclavian to carotid bypass was attempted to provide a longer landing zone for the stent graft. However, due to the previous radiation causing extensive tissue induration and the expanding pseudoaneurysm, the dissection was extremely difficult and was deemed unsafe, and was therefore abandoned. Our first option had been to attempt to place the stent graft through the left axillary artery. The axillary artery was identified through a left axillary incision and was found to be too small for deployment of the stent graft. Because our stent graft was designed for abdominal aortic deployment, the device was too short for a left iliac artery approach to its delivery across the ascending aorta. Our final option was deployment of the stent graft through the left common carotid artery.
A left neck incision was made and the left common carotid artery was dissected. Because of his previous innominate artery ligation, cerebral perfusion during deployment of the stent graft was essential. This assessment was confirmed by a 2-second test of left carotid occlusion with immediate electroencephalogram slowing. To provide cerebral flow, the left internal carotid artery was cannulated with a 14-French cannula and a Y-graft into the cardiopulmonary bypass circuit through the right femoral artery cannula. With antegrade cerebral perfusion accomplished, a Zenith 22 x 55 mm iliac limb extension (Cook) was introduced into the ascending aorta retrograde from the proximal left common carotid artery. Under angiographic guidance, the stent graft was accurately placed excluding the takeoff of the innominate artery stump without compromise of the common carotid artery. After completion, angiography confirmed exclusion of the pseudoaneurysm with no compromise of the common carotid artery and no evidence of an endoleak (Fig 3).
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Fig 3. Completion angiogram demonstrating exclusion of pseudoaneurysm with no compromise of left common carotid artery.
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The patient was allowed to emerge from anesthesia. After the patient was breathing, he was separated from cardiopulmonary bypass under local anesthesia and transferred to the intensive care for postoperative resuscitation. The total bypass time was 281 minutes. He was subsequently discharged from the hospital on postoperative day 5. Computed tomographic scans prior to discharge and at 1-month and 3-month follow-ups have shown no evidence of endoleak or re-expansion of the pseudoaneurysm (Fig 4).
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Fig 4. Computed tomographic scan demonstrating no evidence of extravasation or re-expansion of pseudoaneurysm.
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Comment
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Innominate artery pseudoaneurysms are rare, and usually the result of traumatic injuries [13]. Conventional repair involves a median sternotomy and cardiopulmonary bypass with the possibility of using hypothermic circulatory arrest. Although effective, this approach exposes the patient to significant morbidity and mortality. The endovascular stent graft experience for aortic pathologies initially began as an alternative approach for elective repair of aortic aneurysms. The high-risk patients seem to benefit the most from the minimally invasive endovascular approaches. With initial encouraging results, endovascular repair is currently being evaluated for emergency use in aortic pathologies. There have been reports of emergency treatment with endovascular stent grafts in the thoracic aorta in the setting of traumatic aortic injuries [14–16]. Furthermore, successful endovascular repair of innominate artery pseudoaneurysms from traumatic injuries have also been reported [17, 18]. The initial experiences are encouraging, but long-term results and durability of repair remain to be determined.
Our patient's history presented a unique clinical scenario of an innominate artery pseudoaneurysm developing from a previously ligated tracheal-innominate artery fistula. In addition to the technical challenges of the emergency presentation and the location of the pathology that required stent graft placement in the ascending aorta, challenges unique to this case included management of the airway, hemodynamic support and stability, and neurocerebral monitoring and perfusion. With the history of multiple tracheal and mediastinal operations, not only was endovascular repair the preferable approach, but perhaps the only approach to successfully repair the pathology while preventing eminent or intraoperative mortality. In this patient, open surgical mediastinal dissection in a previously irradiated and a reoperative field would have likely proven to be prohibitively dangerous or technically unfeasible, as demonstrated by our unsuccessful attempt to isolate the left subclavian artery for a subclavian to carotid bypass.
Currently, because there are no commercially made stent graft devices that are designed for ascending aortic pathologies, achieving vascular access for deployment was a technical challenge. The Zenith iliac limb extension (Cook) was the only appropriate covered stent that was available to us at the time of this patient's emergency presentation. Because the stent graft was designed for iliac placement, the length of the deployment device was inadequate and challenges arose as we searched for a vascular access site of appropriate length from the site of required deployment. The innominate artery had been ligated, and the left axillary artery was proven to be too small. The left common carotid artery was the only possible access.
The tenuous status of the airway further complicated the management of this patient. With a pulsatile mass, evidence of impending free rupture at the mediastinal tracheostomy site, and a threatened airway, emergency management of the pseudoaneurysm was essential. In consultation with our anesthesia colleagues, it was believed that any manipulation of the airway and attempted intubation of the tracheostomy may result in rupture and exsanguination. Clearly endovascular repair of the aorta does not routinely involve the use of cardiopulmonary bypass. In this case, cardiopulmonary bypass was instituted for hemodynamic stability, cerebral perfusion, and oxygenation. The management of the airway was challenging, as our operative strategy required induction of intravenous anesthesia after the institution of cardiopulmonary bypass and emergence from anesthesia with spontaneous respiration prior to the termination of cardiopulmonary bypass.
Cerebral perfusion and protection was an additional technical challenge in this scenario. Because of the previously ligated innominate artery, all cerebral circulation was presumptively derived from the left carotid and vertebral system. Because our vascular access involved the left carotid system, this was an additional factor in the decision to use cardiopulmonary bypass. Cerebral perfusion was achieved with the cannulation of the left internal carotid artery and the creation of a Y-graft to the cardiopulmonary circuit. Intraoperative continuous electroencephalogram monitoring and carotid ultrasound assured adequate cerebral perfusion and protection.
Finally, the role of endovascular stent grafts in a potentially infected site and in a pediatric patient remains unclear. Although blood cultures had been negative, the innominate artery pseudoaneurysm had eroded into the mediastinal tracheostomy site. The patient has been maintained on long-term antibiotic therapy. Both the intraoperative completion angiogram and the postoperative computed tomographic chest scan did not suggest the presence of an endoleak or any evidence of infection. The patient was discharged to home on postoperative day 5, neurologically intact, and with no clinical evidence of infection. His 3-month follow-up computed tomographic chest scan confirmed no evidence of infection or endoleak.
In conclusion, endovascular stent graft placement has become an alternative approach to conventional repair of aortic diseases. Its role in the emergent setting for high-risk patients is promising, but remains to be determined. It is this type of patient in whom the conventional surgical approach is not a viable option, but in whom endovascular techniques have their highest therapeutic potential. Although promising, long-term prognosis and the durability of repair when compared with conventional open repair remains to be investigated.
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References
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Abstract
Introduction
