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Department of Thoracic and Cardiovascular Surgery, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio
Accepted for publication August 11, 2011.
* Address correspondence to Dr Roselli, Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic, 9500 Euclid Ave, Desk J4-1, Cleveland, OH 44195-5108 (Email: roselle{at}ccf.org).
Presented at the Fifty-seventh Annual Meeting of the Southern Thoracic Surgical Association, Orlando, FL, Nov 3–6, 2010.
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Abstract |
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Methods: Between July 2001 and December 2010, 31 patients underwent FET and 19 patients underwent RFET for extensive thoracic aortic disease. Causes included aneurysm (n = 32), acute dissection (n = 17), and rupture (n = 1). Twenty-three cases (46%) were for urgent or emergency indications. Patient data and outcomes were collected through a prospectively maintained clinical database and 3-dimensional analysis of computed tomography (CT) scans. Outcomes were assessed using Kaplan-Meier methodology.
Results: In-hospital mortality was 8% (n = 4, including 1 emergency RFET procedure for aortic rupture and 2 urgent FET procedures for symptomatic degenerative aneurysm). Stroke occurred in 5 patients (10%) and spinal cord injury in 4 patients (8%). Mean hospital stay was 14.3 days (range 4 to 67 days). Five endoleaks were observed (4 type II, 1 type I) requiring 2 endovascular reinterventions. Mean follow-up was 17 months (range, 1 to 76 months) and actuarial survival was 87% at 2 years.
Conclusions: Frozen elephant trunk repair is an effective surgical strategy for managing high-risk patients with extensive pathologic conditions of the thoracic aorta. The RFET approach is a feasible option for proximal aortic complications after previous descending stent grafting. Intermediate outcomes are reasonable for both approaches and further evaluation of these techniques is warranted.
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Introduction |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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| Dr Roselli discloses that he has financial relationships with Cook and Medtronic.
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The 2-stage elephant trunk procedure has been the preferred surgical technique for multifocal thoracic aortic disease spanning the ascending segments, the arch, and the descending segments. This staged approach classically entails an initial operation through a median sternotomy with prosthetic replacement of the ascending aorta and aortic arch, leaving a free-floating elephant trunk extension of the arch graft within the descending aorta [1, 2]. This graft extension serves as the site of proximal anastomosis during the second-stage operation, facilitating distal repair. The "reversed" elephant trunk modification refers to scenarios in which the descending aortic segment must be repaired first because of disproportionate aneurysm enlargement, refractory symptoms, or imminent rupture [3, 4].
A frequently reported limitation of the 2-stage elephant trunk procedure is that a number of patients do not undergo the second-stage operation [2, 5, 6]. This is primarily attributable to patient comorbid conditions that preclude another major operation. Furthermore, interval mortality between stages can approach 16%, and the cumulative mortality associated with 2 surgical procedures of this magnitude also ranges between 10% and 16%. Svensson and colleagues [2] demonstrated that failure to complete the second stage severely affected long-term survival, with survival of only 34% compared with 75% in patients who successfully underwent second-stage completion.
An alternative option, espoused by Kouchoukous and colleagues [7], entails single-stage aortic repair through a bilateral anterior thoracotomy. Outcomes, however, are beset with considerable postoperative respiratory and renal failure.
In recent years endovascular techniques have emerged as viable treatment strategies for a wide array of thoracic aortic diseases with the potential for reduced morbidity [8]. This has included the hybrid use of endovascular techniques for elephant trunk completion [9]. The frozen elephant trunk (FET) technique is another hybrid procedure performed in a single stage designed to overcome some of the limitations associated with its 2-stage predecessor [10]. Through a median sternotomy an endograft is deployed antegrade through the transected arch with the patient in deep hypothermic circulatory arrest. This stented elephant trunk is thereby fixed or "frozen" in the descending aorta, with proximal suture fixation of the device to the native aorta completed by conventional proximal aortic replacement. A number of published FET case series from Asia and Europe [11–18] have yielded promising early results that substantiate this technique, but the majority of these procedures used the E-vita hybrid prosthesis (JOTEC GmbH, Hechingen, Germany), which is not commercially available in the United States [12]. At our institution, modified FET procedures are being performed with commercially available stent graft devices. This modified FET technique has also been implemented in extended repair of acute aortic dissections. Additionally, the reversed modification of the FET technique (RFET) has been used for the management of proximal aortic complications, such as endoleaks and retrograde dissection, after descending aortic stent grafting. This surgical variation represents the endovascular/hybrid analog of the reversed modification of the classic open 2-stage elephant trunk technique [2, 3]. The objective of the present study was to evaluate the safety and efficacy of FET and RFET repair in high-risk patients with complex thoracic aortic disease and complications after descending aorta stent grafting.
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Patients and Methods |
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Outcome Definitions
The primary outcomes of this study were hospital mortality and neurologic complications, which were chosen to address the safety of the operation. Neurologic complications included stroke (neurologic deficit >72 hours with CT documentation) and spinal cord injury (transient or permanent paraparesis or paraplegia). Secondary outcomes included morbidities associated with respiratory and renal complications. Respiratory failure was defined as prolonged ventilatory support necessitating eventual tracheostomy. Renal failure was defined as the need for dialysis. Outcomes were stratified according to type and urgency of repair. Intermediate-term outcomes were also assessed and included survival, change in aortic diameter, false lumen patency, and endoleak necessitating endovascular or open surgical reintervention. Aortic morphologic features were assessed with 3-dimensional reconstruction analysis software (TeraRecon, Foster City, CA).
Statistical Analysis
Continuous variables were described as mean ± standard deviation (SD) or median IQR and categorical values were expressed as number (%). The absolute mean difference in maximum aortic diameter between the last available CT scan and the preoperative CT scan was also calculated. Long-term survival was assessed using the Kaplan-Meier methodology.
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Results |
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Overall mean length of hospital stay was 15.3 days (range, 4 to 67 days), with a mean stay of 6 days (range, 1 to 19 days) in the intensive care unit. Length of hospital stay and intensive care unit stay were similar between patients who underwent single-stage repair and those who underwent RFET repair. Adverse neurologic events occurred in 8 patients (16%), including 5 strokes (10%, cause of death in 2 cases described earlier) and 4 cases (8%) of paraparesis, 3 of which were transient after responding favorably to cerebrospinal fluid drainage and permissive hypertension. Of the 3 nonfatal strokes, 1 occurred in a 73 year-old woman with transverse arch and descending aortic aneurysm who suffered intraoperative proximal aortic root dissection with rupture into the mediastinum and massive hemorrhage. Hemostasis was performed and her aortic root was also successfully repaired. Hospital outcomes are summarized in Table 3.
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Comment |
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Unfortunately, spinal cord injury was not avoidable in this cohort, but the majority (75%) of the occurrences of paraparesis were transient (8% overall). The incidence of this complication is similar to that found in most other experiences, including that of Shimamura and associates [15, 21] (Table 4). Three of the 4 patients in the current series underwent previous aortic procedures, a known risk for spinal cord injury [22]. The patients who experienced transient paraparesis had all undergone abdominal aneurysm repair in the past. One patient also had previous descending thoracic aneurysm repair several years earlier, 1 patient presented with acute type A dissection, and 1 patient underwent extensive descending aorta coverage, all of which likely rendered their spinal cords increasingly susceptible to ischemia because of compromised collateral flow. Fortunately these 3 patients responded to emergency placement of an intrathecal drainage catheter and induced hypertension in the intensive care unit. The disproportionately elevated incidence of spinal cord injury (24%) noted in the series of Flores and associates [13] may be directly attributable to the greater proportion (40%) of patients with previous aortic repairs in that study. The authors cited previous abdominal aneurysm repair and a distal landing zone below T7 as independent risk factors for spinal cord injury after FET repair. We now place spinal drains the day before surgery for patients at risk because of previous aortic repair so that we can institute these measures immediately after stent graft deployment. Moreover if the aortic coverage will extend into the distal half of the thoracic aorta, we avoid performing the FET procedure. For these patients, our preferred treatment option is a 2-staged repair, with endovascular elephant trunk completion as the second stage [23]. By deferring the descending repair at least until after the perioperative edema has abated, we think that the risk of spinal cord injury is reduced.
The stroke rate was higher than anticipated but is comparable to most series [21] (Table 4). Of the 5 strokes, only 1 occurred in the electively performed cases (1 of 27, 3.7%). This patient was a 72-year-old woman with chronic dissection, and preoperative imaging demonstrating chronic small vessel (intracerebral) disease by magnetic resonance imaging and moderate bilateral internal carotid stenosis with heterogeneous plaque by duplex ultrasonography. The other 4 strokes occurred in the setting of emergency operations for acute dissection (n = 2), aneurysm rupture (n = 1), and symptomatic aneurysm (n = 1).
Dialysis-dependent renal failure and respiratory failure requiring tracheostomy each occurred in 6% and 4% of patients, respectively. The rates of similarly defined renal and respiratory failure in the study of Shimamura and colleagues [15] were 4.8% and 6.3%, respectively. All 3 patients in whom renal failure developed in our study were undergoing emergency FET repairs performed for acute dissection. One patient had preexisting renal failure and the other 2 patients eventually recovered renal function. Interestingly, all 3 patients with respiratory failure were also emergency cases for acute dissection, including 1 RFET repair. It is also important to relate the incidence of these complications to alternative single-stage approaches in extensive thoracic aortic disease. In the 2 recently published series of electively performed single-stage total aortic repair by bilateral anterior thoracotomy, Kouchoukos and associates [7, 24] reported rates of renal failure and respiratory failure as high as 10% and 18%, respectively.
RFET
The RFET was a modification proposed for patients in whom the distal aorta must be replaced first because of refractory symptoms or actual or impending rupture [3, 25]. Advancements in endovascular stent graft technology and operator skill set have ushered in a veritable shift in the treatment paradigm of complex thoracic aortic disease. Increasingly patients are presenting with proximal aortic complications, including proximal endoleaks, migration, and retrograde dissections. These patients with diffuse aortic pathologic conditions can be safely treated with open reconstruction under circulatory arrest by suturing the conventional graft to the previously placed stent graft. In the current study, reasonably low (5%) mortality was observed despite the urgent/emergency indications for nearly half of the cases. The single early mortality in our RFET series occurred in a patient with a ruptured proximal aneurysm who survived the repair but succumbed to the neurologic sequelae of an ischemic stroke. Based on the successes and refinement of technique in these urgent indications, elective RFET was developed to address patients with small true lumens after chronic dissections.
The endovascular facet of the RFET approach offers a readily discernible advantage over the open reversed elephant trunk. Specifically, this initial minimally invasive component facilitates completion of the 2 stages given the markedly reduced period of recovery required compared with a left thoracotomy. In fact most patients could likely have their second stage proximal repair completed during the same hospitalization. Such was the case for 50% of the patients presented in this series. By expanding this approach to a number of patients who eventually require all segments of the thoracic aorta repaired, the RFET approach will play an increasingly important role in this challenging patient population. More long-term studies with larger patient cohorts comparing this approach with open techniques will be necessary to assess this operation.
Limitations of the Study
The primary objective of this study was to convey our early experience with the modified FET repair as well as with the novel reversed adaptation of this technique. As such the study design was retrospective in nature, with all the implicit biases such methodologies impart. This study was composed of a relatively small group of patients, thus meaningful comparisons with outcomes from other larger series may be deemed scientifically unsound. Interpretation of results from this study is further hampered by the lack of a contemporaneous control group, ie, patients undergoing the classic, 2-stage elephant trunk procedure. Moreover, long-term outcomes were not evaluated in this study and therefore the durability of FET repairs requires ongoing evaluation.
Conclusions
Single-stage FET repair represents an alternative surgical strategy for the management of high-risk patients with extensive pathologic conditions of the thoracic aorta who are traditionally offered a 2-stage open approach. Results from the present study suggest that FET using commercially available stent grafts can be successfully performed with reasonably low morbidity and mortality. For patients with multifocal disease of the thoracic aorta necessitating distal aortic repair first or for those who experience proximal aortic complications after descending aortic stent grafting, the reversed modification of the FET repair is a safe and effective strategy that facilitates timely completion of proximal aortic repair.
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Discussion |
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DR LIMA: All 5 were embolic.
DR MARTIN: In looking back on this, I know they were emergencies, but was there some reason that these embolic strokes were higher in this group than in the standard TEVAR or even in the elephant trunk group, and is there anything you might think about doing differently?
DR LIMA: Well, 1 single stroke that occurred on an elective repair was in an elderly woman with significant intracranial occlusive disease as well as bilateral carotid stenosis. With regard to the other 4 strokes in emergency cases, we didn't have adequate preoperative imaging for stroke assessment. For elective cases it would be preferable to complete a more thorough preoperative risk assessment before deciding to proceed with a procedure of this complexity.
DR MARTIN: I don't know if anybody else has any comments, Dr Roselli, anybody have any comments as to perfusion techniques, because you can do all the workup you want, but most of these embolic strokes come from manipulation of the arch or atheroma or debris in your frozen elephant trunk when you are doing it.
DR ROSELLI: The strokes that we saw in most of these patients (and part of the reason why we selected this approach for these patients) is because they were the kind of patients who had the very diffusely atherosclerotic aortas. When you open it up, it looks like a bomb went off in there with saccular aneurysms and soft atheromatous debris throughout the aorta. The thought was that by using circulatory arrest and limiting the amount of manipulation of the aorta in these people that we could reduce their stroke risk, but we still had strokes in some of these folks, and so I think some of these patients with just really horrible aortas are better off just letting them be, but not all of the strokes were devastating either. We need to be better able to predict stroke in these patients.
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This article has been cited by other articles:
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  E. E. Roselli, A. Rafael, E. G. Soltesz, L. Canale, and B. W. Lytle Simplified frozen elephant trunk repair for acute DeBakey type I dissection J. Thorac. Cardiovasc. Surg., March 1, 2013; 145(3_suppl): S197 - S201. [Abstract] [Full Text] [PDF]
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A. C. Pujara, E. E. Roselli, A. V. Hernandez, L. M. Vargas Abello, J. M. Burke, L. G. Svensson, and R. K. Greenberg Open repair of chronic distal aortic dissection in the endovascular era: Implications for disease management J. Thorac. Cardiovasc. Surg., October 1, 2012; 144(4): 866 - 873. [Abstract] [Full Text] [PDF]
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