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J Thorac Cardiovasc Surg 2008;135:1261-1269
© 2008 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease |
a Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
b Department of Anesthesiology, Osaka University Graduate School of Medicine, Osaka, Japan
c Department of Cardiovascular Surgery, Osaka General Medical Center, Osaka, Japan
d Department of Cardiovascular Surgery, Morinomiya Hospital, Osaka, Japan
Received for publication May 3, 2007; revisions received September 27, 2007; accepted for publication October 31, 2007. * Address for reprints: Yoshiki Sawa, MD, PhD, Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. (Email: sawa{at}surg1.med.osaka-u.ac.jp).
| Abstract |
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Methods: From 1994 to 2004, 126 patients (mean age 67.8 years) with different pathologic conditions of the aortic arch with extension to the descending aorta (57 dissections [acute/chronic = 31/26] and 69 aneurysms) were operated on with an open stent-grafting technique. During deep hypothermic circulatory arrest with selective cerebral perfusion, the stent graft was delivered through the transected proximal aortic arch, and arch replacement with a 4-branched prosthesis was performed.
Results: Operative mortality within 30 days was 3.2%. Perioperative morbidity included 7 (5.6%) strokes and 8 (6.3%) spinal injuries (paraplegia in 3, transient paraparesis in 5). Sixty-three percent of the patients were extubated within 24 hours. In long-term follow-up (mean 60.4 ± 36.5 months, maximum 153 months), survival was 81.1%, 63.3%, and 53.7% at 1, 5, and 8 years. Five (3.9%) late endoleaks were observed but treated with successful additional endovascular repair. Freedom from endoleaks was 98.0%, 91.1%, and 91.1% for 1, 5, and 8 years, respectively.
Conclusion: Long-term observation showed safety and good durability of the open stent-grafting technique for aortic arch disease. This technique could be an attractive treatment option for aortic arch aneurysm with distal extension and aortic dissection requiring aortic arch replacement.
| Introduction |
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Several approaches such as the clamshell incision,1
median sternotomy with left thoracotomy,2
and 2-stage repair with elephant trunk3,4
have been applied in this situation, but a less invasive procedure without left thoracotomy and with completion in a single stage is desired.
Meanwhile, as an emerging, less invasive alternative to conventional surgical repair, thoracic endovascular aortic repair (TEVAR) was brought into clinical use by Dake and his colleagues5
and reported in 1994. Our group has also been using TEVAR since 1993 after animal experimentation,6,7
and satisfactory early outcomes were achieved for type B aortic dissection.8
This method yielded a less invasive alternative for high-risk patients. However, applying TEVAR to aortic arch diseases was difficult because the aortic arch could not provide an adequate proximal landing zone. To mitigate the difficulties in both the distal anastomosis in conventional arch surgery and the proximal landing zone in TEVAR for the aortic arch, our group9
introduced the open stent-grafting technique in 1994. This technique, which subsequently has been described as frozen elephant trunk technique or stented elephant trunk in some articles,10-14
involves conventional replacement of the ascending aorta with a 4-branched graft and stent grafting into the descending aorta through the opened aortic arch. In 2002, we15
reported that this technique is feasible for aortic dissection to obtain clot formation and shrinkage of the false lumen by closing the entry site in the aortic arch and providing continuous compression on the false lumen.
Previous reports10-15
described relatively small series, and it is still controversial whether this technique is safe and useful for long-term results.
The objective of this current report is to elucidate the feasibility of this technique for extended aortic arch replacement and to investigate the long-term durability and efficacy of this hybrid procedure from our 12 years of experience.
| Patients and Methods |
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Informed consent was required in each case. Mean patient age was 67.8 years (range, 35–85 years), and 14 (11.1%) patients were older than 80 years. Thirty-seven (29.3%) operations were of an emergency status. Preoperative comorbidities are shown in
Table 1. Ten (7.9%) patients had previous graft replacement of descending or thoracoabdominal aorta, and 18 (14.3%) had a history of abdominal aortic repair. There were 3 (2.4%) patients with Marfan syndrome.
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Description of the Device
The stent graft was custom-made. It was composed of a Gianturco stent (William Cook Europe A/S, Bjaeverskov, Denmark) and a noncoated polyester fabric graft (WSL graft, Ube, Japan). The diameter of the polyester graft was selected with the measurement results of preoperative 3-dimensional computed tomography (CT). The diameter of the landing zone was calculated by tracing the intimal circumference, and a graft oversized by 10% to 20% was selected. These methods were described in detail in a previous study.9
Average diameter of the stent graft was 25.9 ± 3.5 mm for dissections and 29.5 ± 3.2 mm for degenerative aneurysms. We first used the 30F sheath and pushing rod to deliver the stent graft into the descending aorta. Although this method did not fail to deploy the stent graft, inserting the rigid sheath into the descending aorta under the guidance of transesophageal echocardiography is not easy. In 2001 we developed a sheathless delivery method. The stent graft was mounted on a balloon catheter (20F silicone nephrostomy balloon catheter) and the stented portion was restrained by a silk string. After the stent graft had been inserted into the descending aorta through the transected aortic arch, withdrawal of the restraining string released the self-expandable stented part of the graft.
Surgery
The details of the operation have been described in previous reports.9,15
Via a median sternotomy, the ascending aorta, brachiocephalic artery, and left common carotid artery were dissected. The arterial return cannula was placed in the right axillary artery and femoral artery. Cardiopulmonary bypass was initially started with right axillary perfusion. During core cooling to a 24°C bladder temperature, reconstruction of the left subclavian artery, left common carotid artery, and proximal anastomosis of the 4-branched graft was performed (
Figure 1, A). The left subclavian artery was reconstructed in an extramediastinal fashion at the left infra subclavian space, with the graft branch passing through the second intercostal space. The proximal end of the 4-branched graft was anastomosed to the ascending aorta after cardiac arrest was achieved by crossclamping the ascending aorta and antegrade administration of cardioplegic solution. Selective cerebral perfusion via the 4-branched graft and right axillary artery was established and the perfusion to the lower body was discontinued. The aortic arch was transected at a predetermined line between the brachiocephalic artery and left common carotid artery, and the stented portion of the stent graft was inserted to the descending aorta (Figure 1, B). After deployment, the stented portion was dilated with a balloon catheter under the guidance of transesophageal echocardiography to confirm that the stent graft was fully opened and not kinked. The nonstented graft portion was sutured to the transected stump of the aortic arch, and subsequently continuous anastomosis to the 4-branched graft was made in end-to-end fashion. The debris and air were carefully flushed out from the descending aorta with femoral blood return before this anastomosis was completed. During rewarming, the brachiocephalic artery was reconstructed and the procedure was completed (Figure 1, C). When the ascending aorta was intact and replacement was unnecessary, a bifurcated graft was anastomosed to the ascending aorta instead of 4-branched graft replacement. Reconstruction of the left common carotid artery and left subclavian artery was performed in the same fashion. To prevent ischemic spinal injury, when the time of lower body circulatory arrest extended over 30 minutes, blood return to lower body was established from femoral artery with occluding the stent graft by balloon catheter.
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Patient Follow-up
The follow-up with contrast CT imaging was obtained before hospital discharge, 6 months after the operation, and yearly thereafter. A follow-up CT image was available for 81.9% of patients who survived longer than 6 months. Follow-up clinical status was obtained by medical records from an outpatient clinic or by contacting surviving patients or family members and primary care physician. Follow-up was 92.6% complete, averaging 60.4 ± 36.5 months (maximal follow-up 153 month, total cumulative follow-up = 533 patient-years; 45 patient remaining at risk at 5 years).
Statistical Analysis
All data were reviewed retrospectively. Continuous variables are expressed as mean ± SD and categorical variables as percentages. Survival and freedoms from aortic arch–related death, freedom from endoleaks, freedom from aortic intervention, and freedom from major adverse events were estimated by the Kaplan–Meier method.
| Results |
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Operative mortality within 30 days was 4 of 126 (3.2%). Two death were in acute type A dissection (1 due to postoperative heart failure, 1 due to uncontrollable hemmorage from the aortic root with coagulopathy), and another 2 death were in degenerative aneurysm (1 due to stroke, 1 due to postoperative thoracoabdominal aneurysm rupture). There were 7 in-hospital deaths after 30 days (in-hospital mortality 5.5%). The causes of in-hospital mortality were brain infarction (n = 1), sepsis (n = 3), aortoesophageal fistula (n = 1), rupture of thoracoabdominal aortic aneurysm (n = 1), and acute myocardial infarction (n = 1). Aortoesophageal fistula occurred in a patient with ruptured type B aortic dissection with mediastinal hematoma. This patient was treated successfully with the open stent-grafting technique and the aneurysm was successfully excluded, but an aortoesophageal fistula developed after the mediastinal hematoma had absorbed at 38 days postoperatively. The causes of early death within 1 year are listed in
Table 2. Perioperative morbidity included 7 (5.6%) strokes, 3 (2.4%) cases of paraplegia, and 5 (3.9%) cases of transient paraparesis. No spinal cord ischemia was observed in the patients treated by the delayed exclusion technique. The average number of packed red blood cells transfusions was 14.0 ± 3.1 units and re-exploration for bleeding was required in 3 (2.4%) patients. In 6 (4.8%) with renal failure, transient hemodialysis was required. The length of stay in the intensive care unit ranged from 0 to 60 days, median 4 days.
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The demographics of patients with paraplegia and transient paraparesis are shown in
Table 3. All patients with transient paraparesis had recovered enough to be able to walk by themselves. The median hospital stay was 29 days, and 11 (8.7%) of the patients were discharged to an institution for rehabilitation.
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Operative mortality, aortoesophageal fistula, stent graft–related mortality (perforation, occlusion, and thromboembolism), and cerebral graft–related mortality were defined as aortic arch–related death, and the freedom from aortic arch–related death was 95.8%, 92.4%, and 92.4% at 1, 5, and 8 years, respectively (
Figure 3).
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Late endoleaks were observed in 5 (3.9%) cases (4 in degenerative/atherosclerotic aneurysms, 1 in chronic type B aortic dissection). Type I endoleak from the distal end of the stent graft had occurred in 3 cases, and type III endoleak from the stent-in-stent site in 2 cases. Endoleaks were observed an average of 24.8 months postoperatively, and all of them were successfully treated with additional endovascular repair. Actuarial freedom from endoleaks was 98.0%, 91.1%, and 91.1% for 1 year, 5 years, and 8 years, respectively.
Intervention of another aortic lesion was administered in 10 (7.9%) cases. There were 7 TEVARs and 3 graft replacements (1 thoracoabdominal aortic aneurysm and 2 aascending aortic aneurysms). All of these cases that required intervention for other aortic lesions were aortic dissection cases. The average postoperative duration for intervention of other aortic lesions was 38.3 months (range 3–89 months). Actuarial freedom from aortic intervention (freedom from intervention of endoleaks and other aortic aneurysms) was 97.2%, 83.8%, and 75.4% for 1, 5, and 8 years, respectively.
Major adverse events
In-hospital death, stroke, spinal cord ischemia, aortic rupture, aortoesophageal fistula, and endoleak were defined as major adverse events, and the freedom from major adverse events was 79.9%, 73.8%, and 73.8% at 1, 5, and 8 years, respectively.
| Discussion |
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In this cohort of 126 patients, the overall operative mortality within 30 days was 3.2%. In degenerative aneurysms, the operative mortality within 30 days was 2.9%. This is comparable with the operative mortality within 30 days of the first-stage operation with the elephant trunk technique in contemporary reports (2.1%–12%).16,17
However, the elephant trunk technique requires a second-stage operation (mortality 4%–8.5%) to complete the procedure, and there are even a considerable number of patients who do not survive to the second operation. The open stent-grafting technique has an advantage over the elephant trunk technique in that it completes the procedure within a single operation.
In acute type A dissection, the entire intimal tear resection is desirable to achieve a good fate of the remaining dissected aorta.18
However, extending the procedure to the aortic arch could be associated with increasing mortality.18
In our series, the mortality in acute dissection is satisfactorily low (6.9%), and this could relate to the fact that this procedure could achieve total arch repair without manipulating more distally to the left common carotid artery, which facilitates the control of bleeding.
Postoperative occurrence of vocal cord paralysis after aortic surgery is considered to be an independent predictor of pulmonary complications and leads to a longer duration of hospital stay.19
Even with preservation of the recurrent laryngeal nerve, vocal cord paralysis occurs in 21.9% to 32% of aortic arch operations and in most cases does not return to normal movement.20
Our procedure does not require resection distally to the left artery, and it has the advantage of avoiding recurrent nerve injury. Postoperative vocal cord paralysis was observed in 9.5%, and 58% of them had fully recovered during hospitalization. Mechanical ventilation for more than 72 hours was required in 20.0% in our series and could be low in comparison with other series of aortic arch replacement through a left thoracotomy (36–50%).21,22
These results suggest that the open stent-grafting technique could contribute to reduced postoperative respiratory failure.
Spinal cord ischemia is a devastating complication of aortic surgery. Our series showed 3 (2.4%) cases of paraplegia and 5 (3.9%) of paraparesis. Among the 3 patients with paraplegia, 2 had intraoperatively hypotensive perfusion of the lower body associated with stent graft stenosis. Inasmuch as hypotension is widely known to be a risk factor for the development of spinal cord ischemia,23
stent graft stenosis is an important pitfall of this procedure. Designing the stent graft carefully is mandatory when custom-made stent grafts are used.
Among the 5 cases of temporal paraparesis, 2 were type A acute dissections with preoperative malperfusion. Both of them had a clotted false chamber and severely narrowed true chamber in the descending aorta associated with hypoperfusion of the visceral arteries and lower extremity, which raised concern about the occurrence of spinal cord ischemia. The remaining 3 cases except for the hypoperfusion cases were associated with a history of abdominal aortic repair. From 1997, we started to administer CSFD before the operation in cases of previous thoracoabdominal or abdominal aortic repair. No spinal cord ischemia was observed since then except the 2 cases of acute type A dissection with preoperative malperfusion.
In our study, survival at 1, 5, and 8 years was 81.1%, 63.3%, and 53.7%, respectively. Long-term results of extended aortic arch repair are not well described, but our result is comparable with those of other series of simple aortic arch replacement (5-year survival 46%–79%).23-25
Despite encouraging early results, there are few reports describing long-term results of endovascular stent graft repair. Demers and his colleagues26
reported in their study of 103 TEVARs for descending thoracic aorta that freedom from endoleak was 78%, 64%, and 50% at 1, 5, and 8 years, respectively. Freedom from endoleak in this series was 98.0%, 91.1%, and 91.1% for 1, 5, and 8 years, respectively, which could be superior to TEVAR. TEVAR is inevitably associated with some frequency of proximal type I endoleak in the early and long-term follow-up periods, but this is avoidable in the open stent-grafting technique because the proximal end of the stent graft was sutured in a surgical fashion. All 5 patients who had a late distal endoleak were successfully treated with additional TEVAR, and there have been no secondary endoleaks.
Although shrinkage of the aneurysm sac after endovascular repair may be desirable, the persistence of the aneurysm does not represent a failure because a stable aneurysm without endoleak has not been linked to any untoward effects.27
On the other hand, sac enlargement implies increased pressure within the aneurysm sac and should be treated promptly. In our series, 3 aneurysms showed enlargement on late follow-up and all of them were associated with type I/type III endoleaks. Also, we have to consider that the intercostal arteries are opened to the excluded aneurysm (type II endoleak) and this requires that the transected stump of the aortic arch be sutured to the stent graft. Inasmuch as these issues should be carefully studied, we perform postoperative CT with contrast medium at the arterial phase and delayed phase to detect endoleaks.
However, type I/type III endoleaks can be treated with additional endovascular repair with a good result. According to type II endoleak, Ohki and colleagues28
had reported a study using an implantable wireless aneurysm pressure sensor for endovascular repair of abdominal aorta. They showed that the postexclusion pulse pressure was significantly decreasing. In no patient in our series was trouble caused by the pressure inside the aneurysm, such as continuous leaking from ruptured aneurysm or enlargement of the aneurysm with type II endoleak. From these results, the pressure inside the aneurysm (endotension) could be low enough in the clinical point of view.
Limitation of the Study
This is a retrospective cohort study, and the lack of a concurrent control group restricts direct comparison with total arch replacement associated with left thoracotomy. For the precise advantage of open stent-grafting technique to be elucidated, a prospective case–control study would be required. This study includes our earliest experience with stent grafting, so both the technical immaturity and the lack of adequate spinal protection could have caused spinal ischemia. Improved stent graft design, delivery system, and consideration of spinal protection could be associated with better outcomes.
| Conclusion |
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| Footnotes |
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| References |
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