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Ann Thorac Surg 2001;72:1232-1238
© 2001 The Society of Thoracic Surgeons

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Original article: cardiovascular

Single-stage transmediastinal replacement of the ascending, arch, and descending thoracic aorta

^a Division of Thoracic and Cardiovascular Surgery, University of Florida, Gainesville, Florida, USA

Address reprint requests to Dr Beaver, Division of Thoracic and Cardiovascular Surgery, University of Florida, 1600 SW Archer Rd, Room M602, Gainesville, FL 32610-0286
e-mail: beavetm{at}mail.surgery.ufl.edu

Presented at the Forty-seventh Annual Meeting of the Southern Thoracic Surgical Association, Marco Island, FL, Nov 9–11, 2000.

	Abstract

Top Abstract Introduction Patients and methods Results Comment Discussion References

 
Background. Aneurysms of the ascending, arch, and descending thoracic aorta are typically managed with two operations. The first stage involves replacement of the ascending and arch aorta leaving a segment of graft in the proximal descending aorta with a mortality and stroke risk of 8%. The second stage involves replacement of the descending aorta with a mortality of 5% and a paraplegia risk of 5% to 10%. Some patients refuse surgical completion and others are at increased risk to undergo the second stage thoracotomy, leaving them with untreated descending thoracic aortic aneurysms vulnerable to rupture. A single-stage transmediastinal operation used in 14 patients is described.

Methods. Under circulatory arrest, the descending thoracic aorta is opened. A wire is passed up to the arch and a graft is brought down and secured excluding the descending thoracic aneurysm. The arch vessels are attached as a single patch and the graft is brought forward, replacing the ascending aorta.

Results. Fourteen patients have undergone single-stage replacement of the ascending, arch, and descending aorta with a 14% mortality rate and 14% incidence of paraplegia.

Conclusions. Patients with aneurysms of the ascending, arch, and descending thoracic aorta can be managed with a single operation with comparable mortality and morbidity of the two-stage approach.

	Introduction

Top Abstract Introduction Patients and methods Results Comment Discussion References

 
The 5-year survival of patients with thoracic aortic aneurysms is five times greater among those who undergo elective surgery compared with those who do not [1]. Left untreated, the cause of death in patients with thoracic aortic aneurysms will be rupture in 44% to 56% of cases [1, 2]. The staged "elephant trunk technique" introduced by Borst and colleagues [3–5] in 1983 has become the standard for repair of aneurysms of the ascending, arch, and descending aorta. Using the elephant trunk technique, patients initially undergo repair of the ascending and arch component of their aneurysm through a median sternotomy and a residual length of graft (the "elephant trunk") is left dangling free in the descending aorta; this facilitates the proximal anastomosis when patients return 6 to 8 weeks later for repair of their descending aneurysm. The first procedure is associated with significant morbidity and mortality (7% to 10%, more recently) [6–8]. Because of this, patients are reluctant or unable to return for the second operation, which carries its own complications (paraplegia, 5% to 10%) and mortality (3% to 5%) [7–9]. Patients who do not undergo the second stage are left with large descending aneurysms vulnerable to rupture [4, 8]. Accordingly, we have developed a single-stage transmediastinal operation for aneurysms of the ascending, arch, and descending aorta. In this operation the ascending aorta and proximal arch are repaired as in the standard elephant trunk operation but the distal graft is anastomosed to the descending aorta through a transmediastinal exposure. The results in the first 14 patients are described.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment Discussion References

 
Operative procedure
Patients with aneurysms involving their ascending, arch, and descending thoracic aorta who traditionally would be treated with an elephant trunk approach and who have descending aneurysms that taper to a normal caliber aorta before the level of the diaphragm are candidates for this procedure. Standard median sternotomy is performed. Patients are administered heparin and cannulated in the ascending aorta after epiaortic echocardiography confirms the absence of thrombus. A two-stage venous cannula is placed in the right atrium and a retrograde cardioplegia catheter is placed in the coronary sinus. All patients receive Aprotinin (Bayer, West Haven, CT); typically a high dose (2,000,000 U intravenous load, 2,000,000 U in the pump prime, and 500,000 U per hour) is administered. One gram of Solu-Medrol (Pharmacia Upjohn, Kalamazoo, MI) is in the pump prime. Patients are placed on bypass and cooled; a vent is placed in the right superior pulmonary vein upon fibrillation. Bypass is discontinued when the electroencephalogram is silent (18°C by bladder and esophageal probes). Cardioplegia is initially administered antegrade with direct coronary ostial cannulas then subsequently with retrograde perfusion at 20-minute intervals. During circulatory arrest retrograde cerebral perfusion is employed through a cannula in the superior vena cava.

The patient is placed in a steep Trendelenburg position and the entire ascending aorta is excised and the transverse arch is opened longitudinally. The heart is retracted cephalad and the descending aorta is exposed through the posterior pericardium and opened transversely. A guidewire is passed from the descending aorta up into the arch. A woven Dacron graft is then pulled down into the descending thoracic aorta using the wire as a guide and anastomosed to the descending thoracic aorta at the level of the transverse aortotomy (Fig 1). This anastomosis effectively seals the upper descending thoracic aorta from retrograde flow. The arch vessels are reimplanted in the graft as a single anastomosis and the transverse arch aortotomy is closed around the graft. At this time the graft is inverted and sewn to the aortic wall proximal to the arch vessels, sealing the aorta around the graft effectively excluding the arch and descending aorta from systemic flow and pressure (Fig 2). Collateral vessels feeding the body of the aneurysm appear to thrombose as seen with thoracic stent grafts (Fig 3). We find sewing proximal to the arch vessels as described by Kusuhara [10] technically easier than sewing distally as described by Borst and colleagues [3] and Heineman and associates [4]. At this point the graft is unfolded and deaired, and the aortic cannula is placed in the graft. The proximal graft is then sewn to the ascending aorta. The patient is rewarmed and weaned from cardiopulmonary bypass. Follow-up computed tomography scans are performed before discharge to confirm absence of leakage at anastomotic sites and thrombosis of the excluded aneurysmal segment around the graft (Fig 3).

View larger version (43K): [in this window] [in a new window]   Fig 1. Technique for distal aortic anastomosis using the single-stage transmediastinal technique. (A) The heart is retracted cephalad and the pericardium is incised to expose the descending thoracic aorta. (B) A wire is passed into the arch to guide the graft down through the aorta. (C) The distal anastomosis is completed.

View larger version (41K): [in this window] [in a new window]   Fig 2. Modified "elephant trunk" technique as described by Kusuhara showing (A) anastomosis of the arch vessels, with (B) the aorta sealed around the graft anterior to the arch vessel anastomosis.

View larger version (89K): [in this window] [in a new window]   Fig 3. Postoperative computed tomography scan showing thrombosis of an ascending, arch, and descending thoracic aneurysm around a graft placed through the single-stage transmediastinal approach.

	Results

Top Abstract Introduction Patients and methods Results Comment Discussion References

One patient (number 14) was dialysis dependent preoperatively. Renal failure developed postoperatively in 4 (28%) patients; this resolved in 2 patients and the other 2 patients eventually died of multiple organ failure. Five patients (35%) required tracheostomy. One patient eventually required a DDD pacemaker. The first patient required reoperation for bleeding. Length of stay (LOS) after the operation ranged from 8 to 77 days with a mean of 31 days. However, 4 patients were discharged home after reasonably short stays. There were no perioperative deaths; 2 patients (14%) died in hospital. Both hospital deaths were from multiple organ failure; 1 of these was the patient (number 10) who had sustained a brainstem stroke.

Follow-up ranged from 5 to 54 months (Table 4). Seven patients are alive and doing well, although some had prolonged recovery times. One patient was paralyzed but states he is otherwise doing well. Another patient is alive but complains of balance difficulties. There were 3 late deaths at 5, 14, and 28 months after surgery—1 of pneumonia and 2 of unknown etiology. In this elderly patient population with complex and extensive aortic disease, 50% had excellent results; 14% had acceptable results. There were 2 (14%) hospital deaths and 3 (21%) late deaths.

	Comment

Top Abstract Introduction Patients and methods Results Comment Discussion References

The second operation itself carries significant risk for morbidity and mortality. Heinemann and associates [4] reported paraplegia in 3 of 24 patients (12.5%) undergoing downstream procedures but no deaths. Williams and coworkers [9] report a 3% to 10% risk of a spinal cord injury in descending aortic aneurysms. Svensson and colleagues [7] reported a 5% mortality for the second-stage procedure. Furthermore, in an era of cost containment there is a significant savings by avoiding a second operation.

Accordingly, we have developed a single-stage transmediastinal approach for patients with ascending, arch, and descending aneurysms. We consider all patients with aneurysms of their ascending, arch, and descending thoracic aorta who traditionally would be treated with an elephant trunk approach and who have descending aneurysms that taper to a normal caliber aorta before the level of the diaphragm to be candidates for this procedure. The decision to proceed with a single-stage operation is made based on technical considerations (extent and size of the aneurysm at the level of the diaphragm). The size of the graft was typically that of the descending aorta, although in patient 9 a 28-mm graft was sewn into a slightly larger 33-mm descending aorta. We advocate consideration of this operation for all patients despite comorbidities as the single-stage approach assures completion at a risk at or less than that of a staged approach.

There are potential pitfalls with a one-stage exclusion technique including the theoretically increased risk of paralysis incurred by not reimplanting the spinal arteries and the potential for later dilation of the aneurysm around the graft if collateral vessels do not thrombose. However, in this small series computed tomography scans before discharge have shown thrombosis of the aneurysms in all patients.

Borst and coworkers [5] have previously described leaving a long distal elephant trunk in a patient with a descending aneurysm who underwent coronary bypass grafting for unstable angina. In this patient there was no ascending or arch component and the graft was not secured distally; the large descending aneurysm subsequently thrombosed around the graft without sequelae. The use of a long distal elephant trunk in acute aortic dissection of the descending aorta has also been reported by Buffolo and coworkers [11]; the mortality rate was 15% and the complication rate was 60%. In contrast to acute dissection, patients with aneurysmal disease usually have mural thromboses, which theoretically may lead to improved development of collaterals and thus preserved spinal artery flow; because of this, a long elephant trunk may not be ideal for cases of dissection. However, Crawford and associates [12] and Svensson [13] have noted postoperative paraplegia in patients with aneurysms who had long elephant trunk segments.

The Stanford University group has described endovascular stenting of descending thoracic aortic aneurysms [14, 15]. Before the procedure aortography is performed to delineate intercostal, visceral, and arch vessel anatomy. A stent graft is then placed through a cut-down on the femoral artery or retroperitoneal aorta. This group’s most recently reported series of 103 patients revealed a mortality rate of 9%, a stroke rate of 7%, and a paraplegia rate of 3%; 5 patients required surgical intervention [15]. Complete thrombosis of the aneurysms was eventually achieved in 86% of patients. Although they had no late ruptures after stent graft placement, it has been reported [16]. The major reason for incomplete thrombosis around the stent grafts was attributed to perigraft leaks or "endoleaks" found in 24% of their patients. That should not be seen in the transmediastinal approach as the graft is sutured into position. None of our patients has had late rupture from intercostal vessels or from endoleaks.

The concern for neurologic sequelae with transmediastinal single-stage repair of ascending, arch, and descending aneurysms has been mitigated to some degree by the Stanford stent experience, as they report only a 3% paraplegia incidence after stent grafting of the descending thoracic aorta [15]. However, we did see neurologic deficits in 2 of our 14 patients. Of note, 1 of our patients (number 13) had undergone a previous aortobiiliac repair for an abdominal aortic aneurysm, which when combined with the thoracic aorta replacement may have left him with inadequate spinal perfusion. Of the 3 patients with paraplegia in the Stanford stent series, 1 had undergone an aortobifemoral bypass [15].

Although it was not performed in this series it may be necessary that all patients undergoing single-stage transmediastinal repair undergo thoracic aortic arteriography to assure that no major spinal arterial compromise will occur with graft exclusion. The greatest contribution of blood supply to the anterior spinal artery of the spinal cord comes from the artery of Adamkiewicz, which arises from the collateral network of intercostal vessels between T9 and T12 in approximately 70% of patients. Williams and colleagues [9] performed selective arteriography in 47 patients with extensive thoracoabdominal aneurysms to identify this vessel but they were only able to localize it 55% of the time.

Minale and colleagues [17] have also described replacement of the entire thoracic aorta in a single-stage operation in 12 patients using a bilateral thoracotomy technique in 7 patients and a sternotomy in 5. They had 2 perioperative deaths. Interestingly they did not reimplant intercostals and in fact oversewed them. They had no spinal cord injury and postulated that profound hypothermia had a protective effect. Massimo and associates [18] have described single-stage replacement of the entire aorta from the aortic valve to the iliac bifurcation. Using both a median sternotomy and a thoracoabdominal incision under deep hypothermia, this operation was performed in 21 patients with combined thoracic and abdominal emergencies. There were 3 deaths in the first month, for a mortality rate of 14%. They had neurologic deficits in 3 patients (14%); however, in contrast to our experience their deficits were all reversible. Of note, all 3 of these patients did have intercostal reimplantation. Our mortality of 14% compares favorably with these reports and with the literature if one were to combine the mortality associated with both stages of the elephant trunk procedure [4, 7, 8]. Even though our overall morbidity was high in this small series, we believe that with experience the transmediastinal approach through a standard median sternotomy will prove to be the least morbid of the single-stage techniques.

Our overall circulatory arrest times (mean 72 minutes) were longer than expected with a standard elephant trunk procedure and may have contributed to the development of multiple organ failure in 3 patients, 2 of whom died. Svensson and colleagues [7] have shown the risk of stroke increases with the length of circulatory arrest. Despite long circulatory arrest times, we had only 1 brainstem stroke, in a patient who had replacement of all her arch vessels under both circulatory arrest and isolated antegrade perfusion. We attribute the increased circulatory arrest times to a multitude of factors including proper placement and alignment of the descending graft and closure of the descending aorta through the posterior pericardium.

In a technique similar to our described transmediastinal aortic replacement, the Stanford group has performed initial elephant trunk repair of an ascending and arch aortic aneurysm through a median sternotomy followed by stent exclusion of a descending aneurysm in a patient with a forced expiratory volume in 1 second of 1.13. The patient avoided a potentially morbid thoracotomy, had no neurologic compromise, and the descending aneurysm thrombosed around the graft [19]. However, the Stanford group later reported 3 cases of stent grafting after ascending repair, and 1 patient needed emergency repair of the descending aorta, which ruptured during placement of a stent graft [14].

With transmediastinal aortic replacement the morbidity and cost of a second surgical or stenting procedure is obviated. Furthermore, no patients are left with untreated descending aneurysms vulnerable to rupture. Therefore, in our institution single-stage transmediastinal replacement of the thoracic aorta is considered for all patients with ascending, arch, and descending aneurysms that have tapering of the descending aneurysm at the level of the diaphragm. With increased experience we believe the morbidity and mortality associated with this procedure will decrease, making it the procedure of choice in our institution for these complex and technically demanding cases.

	Discussion

Top Abstract Introduction Patients and methods Results Comment Discussion References

 
DR THORALF SUNDT (St. Louis, MO): I would just note a word of caution. When reviewing the literature for the expected incidence of paraplegia and complications, it is critical that you pay attention to which techniques were used. Significant progress has been made in this area in the treatment of thoracoabdominal aneurysms, and in fact one such paper is being presented on this program. At Washington University, we have adopted Dr Safi’s technique of visceral artery perfusion, et cetera, combined with left atrial to femoral bypass in our thoracoabdominal aneurysms and have seen a significant reduction in the mortality risk and the incidence of paraplegia. It is important that you predict expected mortality and morbidity on the basis of contemporary, not historical reports. I would also note that you may not want to take too much comfort from the stent graft experience thus far. Among 9 patients, we have already seen 1 case of paraplegia with the stent grafts.

DR BEAVER : Thank you for your comments. In fact, when we do descending thoracic aneurysms, we do use the techniques of Dr Safi (distal femoral perfusion and spinal CSF drainage). The approach I am presenting is simply to treat that subset of patients that have ascending arch and descending aneurysms and to address the problem of patients not being completely treated. I would submit that if you only do the ascending or first stage of an elephant trunk procedure and don’t complete the second stage, you haven’t served that patient population.

	References

Top Abstract Introduction Patients and methods Results Comment Discussion References

 

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This Article Abstract Full Text (PDF) 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): Thomas M. Beaver Tomas D. Martin Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Beaver, T. M. Articles by Martin, T. D. Search for Related Content PubMed PubMed Citation Articles by Beaver, T. M. Articles by Martin, T. D. Related Collections Great vessels