Ann Thorac Surg 2004;77:1304-1308
© 2004 The Society of Thoracic Surgeons
Original article: cardiovascular
Thoracoabdominal aortic aneurysm repair through redo left-sided thoracotomy
Nobuyoshi Kawaharada, MD, PhD*a,
Kiyofumi Morishita, MD, PhDa,
Johji Fukada, MD, PhDa,
Yoshikazu Hachiro, MD, PhDa,
Kazuhiro Takahashi, MD, PhDa,
Tomio Abe, MD, PhDa
a Department of Thoracic and Cardiovascular Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
Accepted for publication September 22, 2003.
* Address reprint requests to Dr Kawaharada, Department of Thoracic and Cardiovascular Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
e-mail: nobuyosh{at}sapmed.ac.jp
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Abstract
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BACKGROUND: The outcome of thoracoabdominal aortic aneurysm repair through redo-left thoracotomy after operations for descending thoracic aortic aneurysms was investigated.
METHODS: Between May 1982 and March 2003, 100 patients underwent thoracoabdominal aortic aneurysm repair in elective surgery without profound hypothermic circulatory arrest. Thirty of these patients had previously undergone operations for descending thoracic aortic aneurysms. To evaluate the influence of previous descending thoracic aortic aneurysm repairs on the results of thoracoabdominal aortic aneurysm replacements, patients were divided into two groups: (1) patients who had previously undergone descending thoracic aortic aneurysm repair (group I; n = 30), and (2) patients who had not previously undergone descending thoracic aortic aneurysm repair (group II; n = 70).
RESULTS: The distal aortic perfusion time and operation time were both longer in group I than in group II, but there was no significant difference between the two groups in total selective visceral and renal perfusion time or aortic clamp time. In-hospital mortality rates were 13% in group I and 19% in group II (p = 0.52). Major postoperative complications included paraplegia (10% of patients in group I and 4.3% of patients in group II; p = 0.36), renal failure requiring hemodialysis (20% of patients in group I and 11% of patients in group II; p = 0.35), respiratory failure (30% of patients in group I and 19% of patients in group II; p = 0.22).
CONCLUSIONS: Previously descending thoracic aortic aneurysm and redo-left thoracotomy do not adversely affect the outcome of thoracoabdominal aortic aneurysm repair.
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Introduction
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The long-term results of most thoracic or thoracoabdominal aortic aneurysm (TAAA) reconstructions are satisfactory. However, some patients require a reoperation for a separate aneurysm after the original aortic reconstruction. Thus, there is quite a high risk of development of multiple aortic aneurysms in cases of thoracic or thoracoabdominal aortic aneurysms. Crawford and Cohen [1] reported that multiple aneurysms developed in 59.6% of patients who originally presented with aortic aneurysms involving the ascending, transverse arch, or descending segments, whereas multiple aneurysms developed in only 12% of patients who initially had abdominal aortic aneurysms. Carrel and colleagues [2] reported that 36 (27.7%) of the 130 thoracic aortic reoperations performed in their series of 120 patients were due to new or recurrent aortic aneurysms. Of the 1,509 patients in Crawford's complete TAAA experience reported by Svensson and colleagues [3], 181 patients (12%) had previously undergone a proximal aortic operation; this group of patients was characterized by a lower 30-day mortality rate than that in the group of patients who had not previously undergone thoracic aortic aneurysm repair (4% in the group with previous thoracic aortic aneurysm repair vs 9% in the group without previous thoracic aortic aneurysm repair; p = 0025). Furthermore, Coselli and colleagues [4] reported that previous thoracic aortic aneurysm repair did not adversely affect the outcome of thoracoabdominal aortic aneurysm repair.
The complication and mortality of TAAA repair in patients who have previously undergone thoracic descending aortic aneurysm repair remains uncertain because there have been few reports on results of TAAA repair performed in patients who had previously undergone surgery by a left thoracotomy approach for treatment of aneurysm of the descending thoracic aorta. Therefore, we retrospectively evaluated our experience with TAAA repair to compare the results of patients who had undergone previous descending thoracic aortic aneurysm repair with those patients who had not undergone this previous repair.
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Material and methods
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Patients
During the period from May 1982 to March 2003, 100 patients underwent thoracoabdominal aortic aneurysm repair in elective surgery without profound hypothermic circulatory arrest. Data from the hospital records of these patients were obtained from our departmental registry. These 100 patients included 70 men (70%) and 30 women (30%), whose ages ranged from 29 to 78 years (median, 61 years). There were 11 patients (11%) with Marfan's syndrome. Thirty-nine patients (39%) had aortic dissection and 61 (61%) had nondissecting aneurysms. Nine of the patients presenting with dissection had Marfan's syndrome. Mean aneurysm size was 64 ± 13 mm. Associated risk factors included hypertension in 58 patients (58%), chronic renal insufficiency (serum creatinine > 1.5 mg/dL) in 8 patients (8%), and diabetes in 6 patients (6%). According to the TAAA extent classification of Crawford and colleagues [5], 24 aneurysms (24%) were extent I, 26 (26%) were extent II, 34 (34%) were extent III, and 17 (17%) were extent IV.
Thirty of the 100 patients (30%) had previously undergone operations for descending thoracic aortic aneurysm. To evaluate the influence of previous descending thoracic aortic aneurysm repair on the results of TAAA replacement, patients were divided into two groups: (1) patients who had previously undergone descending thoracic aortic aneurysm repair through a left thoracotomy (group I; n = 30), and (2) patients who had not previously undergone descending thoracic aortic aneurysm repair (group II; n = 70). The characteristics of these patients in the two groups are shown in Table 1.
Twenty of the 30 patients (67%) in group I had dissection (p < 0.0002). Six of the 11 patients (55%) with Marfan's syndrome were also in group I. Deep hypothermic circulatory arrest for spinal cord protection was not used in any of the patients in group I or group II.
Surgical procedure
The patients were treated according to a previously reported procedure [6]. Briefly, under double-lumen endotracheal-tube anesthesia, a left thoracoabdominal incision was made with circumferential division of the left hemidiaphragm. Dissection was performed along the extraperitoneal plane. After dissection was completed, a femoro-femoral bypass was started with full heparinization. Lower body blood pressure was maintained at more than 50 mm Hg. A clamp was placed proximal to the aneurysm. The aorta was transected above the aneurysm and anastomosed proximally in an end-to-end fashion to a woven Dacron graft. Although the proximal end was being anastomosed, segmental, visceral and renal arteries were perfused by placing a distal clamp at the midthoracic level. Next, the distal clamp was moved to the supra-celiac level, patent intercostal arteries at the T4 to T8 level were oversewn, and segmental arteries below the T9 level (if patent) were reconstructed using the inclusion button technique. After implantation of the segmental arteries, the proximal clamp was moved below these arteries, allowing perfusion of the lower intercostal and lumbar arteries. Visceral and renal arteries were also reimplanted as a large Carrel patch or preserved in a beveled distal aortic anastomosis. During reconstruction, selective visceral and renal perfusions with 10 to 12 French balloon cannulas were performed by clamping the outflow tubing to the lower extremities. Each artery was perfused at a flow rate of 200 to 300 mL per minute [7]. After completion of the anastomosis of the visceral and renal arteries, the balloon cannulas were removed from the origins of these arteries, and the clamp was placed across the graft distal to the reimplanted arteries, thereby restoring flow to the reimplanted arteries. The distal end of the graft was sutured to the aortic bifurcation or the common iliac arteries.
Because spinal cord ischemia occurred in more than 10% of all patients including emergency patients operated on by using the previously described surgical procedure, we decided to modify the procedure to attempt a reduction in the incidence of postoperative neurologic complications. In the modified procedure, a prosthesis is prepared by suturing 8-mm grafts to an aortic graft. Small tubular grafts are used as interposition grafts for reattachment of individual intercostal or lumbar arteries. Proximal anastomosis is performed in the usual fashion. After completion of anastomosis, the proximal clamp is positioned on the graft, and the distal clamp is placed at a level between T8 and T9. Before T8 arteries are reattached to the sidearm grafts, the intercostal arteries above the T7 level are oversewn. After the reconstruction of T8 arteries, the proximal clamp is moved caudally below the reconstructed sidearm grafts while maintaining perfusion to the reimplanted arteries. The distal clamp is then moved to a level between T9 and T10. In the same fashion, patent segmental arteries are reconstructed segment-by-segment from the T9 level to the L1 level. The reason for reimplanting all patent arteries between T8 and L1 is that the blood supply to the spinal cord in 91% of patients is provided by some arteries from T8 through to L1 and the great anterior medullary artery (the artery of Adamkiewicz, arteria radicularis magna) does not always originate from the larger segment arteries [8]. The segment-by-segment reattachment technique is used to shorten the ischemic time as much as possible. The mean time required for reconstruction of the individual arteries is less than 10 minutes. The nonused sidearm grafts are occluded and sutured. However, the T8 through L1 operative strategy has some problems, that is, reattaching all of these arteries from T8 to L1 prolongs the clamping time, which may cause spinal cord injury, and also some of the arteries that are reattached may not need to be reattached. Obviously an accurate and reliable technique for identifying arteries that need to be reattached is required. In our patients, if the Adamkiewicz artery existed in the region of graft replacement in TAAA, only intercostal or lumbar arteries in aneurysms that were detected as the origin of the Adamkiewicz artery were reattached to the graft.
Since 2000, we have been using magnetic resonance angiography for preoperative detection of the Adamkiewicz artery to reduce the incidence of ischemic injury of the spinal cord and reduce the time of an operation for repair of an aneurysm of the thoracoabdominal aorta [9]. We have also been able to perform femoro-femoral bypass by using a heparin-coated perfusion apparatus with a centrifugal pump (Carmeda Closed Chest Support System [Medtronic, Anaheim, CA]) that has allowed us to reduce the heparin dosage [10]. We have adjusted flow rates to keep the mean distal aortic pressure above 50 mm Hg, and we have carried out visceral and renal perfusion in conjunction with distal aortic perfusion. Each flow rates depends on visceral or renal vessel resistance and ranges from 80 to 220 mL per minute (mean flow rates, 155 mL/min). Blood flow rate is considered appropriate when the patient's urine output is 0.5 mL per minute [11].
Statistical analysis
Data were processed using Stat View J-5.0 software (Abacus Concepts Inc, Berkeley, CA). Variables in group I and II were compared using the 
2 test, Fisher's exact test, and the Mann–Whitney U test. Data for times and age are presented as means ± standard deviation.
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Results
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The average duration between the first and second operation was 2,316 days (6.3 years). Twenty-four of the 30 patients in reoperations had intercostal artery reattachment.
We modified the surgical procedure to try to reduce the incidence of postoperative neurologic complications in 1996. However there is no significant difference between the numbers of patients with spinal cord injury before and after modification of the operative technique. The incidence of paraplegia before modification of the operative technique was 6.4% (4 of 63 patients who underwent elective operations), whereas the incidence of paraplegia after modification of the operative technique was 5.4% (2 of 37 patients who underwent elective operations).
With regard to intraoperative techniques (Table 2),
the distal aortic perfusion time and operative time were longer in group I than in group II, but there was no significant difference between the two groups in total selective visceral and renal perfusion time or total aortic clamp time.
The overall 30-day and in-hospital mortality rates for the 100 patients treated with TAAA repair were 8% (8 patients) and 17% (17 patients), respectively. There was one intraoperative death due to hemorrhage secondary to rupture, and this patient was excluded when calculating and analyzing morbidity rates. Rates of mortality, paraplegia or paraparesis, renal failure, pulmonary complication, postoperative bleeding, and gastrointestinal complications are summarized in Table 3.
The incidence of paraplegia or paraparesis was 6% (6 patients). Twelve patients (12%) were returned to the operation room due to postoperative bleeding. Postoperatively, 22 patients (22%) had pulmonary complications, 8 patients (8%) had gastrointestinal complications, and 14 patients (14%) had renal failure, which required temporary or chronic hemodialysis. There were no statistically significant differences between the rates of these complications or rates of renal failure in group I and group II. Although the differences did not reach statistical significance, postoperative paraparesis or paraplegia rates were higher in patients who had undergone previous descending thoracic aortic aneurysm repair. However, there was no significance difference between in-hospital mortality rates in the two groups. There was also no difference between the causes of in-hospital mortality for patients who had undergone previous descending thoracic aortic aneurysm repair and those who had not (Table 4).
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Comment
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The patients who had not previously undergone descending thoracic aortic aneurysm repair (group II) were older than those who had previously undergone descending thoracic aortic aneurysm repair (group I), but no significant difference was found between incidences of comorbid diseases in group I and group II. There was no significant difference between complication rates or mortality rates in the two groups. In group I patients, there was a greater risk of lung damage during thoracotomy due to lung adhesion; it was believed that there would be a higher incidence of postoperative respiratory complications in this group, but a significant difference between incidences of pulmonary complications in the two groups was not found. The fact that there were more Crawford type I patients in group II may have been the cause of the higher incidence of pulmonary complications in group II.
More patients who had previously undergone descending thoracic aortic aneurysm repair (group I) had Marfan's syndrome than did those patients who had not previously undergone such aneurysm repair (group II). An increase in chronic dissection accounted for 64% of the causes of TAAA in group I (p = 0.003). The larger proportion of patients with Marfan's syndrome in group I undoubtedly contributed to these differences in age and coexisting disease. However the fact that there was no significant difference between complications in the two groups suggests that chronic dissection has no effect on the probability of paraplegia or other postoperative complications occurring. Coselli and colleagues [12] reported that chronic aortic dissociation is not a risk factor for postoperative paraplegia in cases of TAAA.
Despite having less extensive aneurysms and shorter clamp and perfusion times, the 30-day mortality and in-hospital mortality rates in patients in group II were higher. However there was no significant difference between the two groups in 30-day mortality rates or in-hospital mortality rates. An intrinsic selection bias for group I may have contributed to the lower 30-day mortality rate in this group. Careful medical follow-up after the initial operation may have resulted in risk factor prevention. In addition, because some patients who would have needed future TAAA repair did not survive their initial aortic operation, several patients with significant comorbid disease may have been automatically eliminated from group I. Therefore by surviving the previous operation, the group of patients who had previously undergone descending thoracic aortic aneurysm repair may have been inherently more likely to tolerate the TAAA repair compared with those who had not previously undergone the descending thoracic aortic repair.
Although a significant difference was not found between incidences of postoperative paraplegia in the two groups in the present study, the incidence of paraplegia was higher in the patients who had previously undergone descending thoracic aortic aneurysm repair. However, Coselli and colleagues [4] reported a low rate of paraplegia in patients who had previously undergone descending thoracic aortic aneurysm repair.
Many recent studies have shown that cerebrospinal fluid drainage is useful for protection of the spine [13]. We have been using cerebrospinal fluid drainage since 1999, but we have not yet accumulated sufficient case data to be able to conclude whether cerebrospinal fluid drainage is effective or not.
Recent developments in the noninvasive technique of magnetic resonance angiography have enabled detection of the Adamkiewicz artery before an operation for descending or thoracoabdominal aortic repair [9, 14]. Identification of this artery has provided useful preoperative information. To prevent ischemic injury of the spinal cord, preoperative detection of an intercostal artery that may be related to the Adamkiewicz artery is very useful for establishing the best strategy for an operation for descending aortic aneurysm or thoracoabdominal aortic aneurysm repair, because surgical repair can be performed with intensive care to revascularize the intercostal and lumbar arteries at or near the level of the Adamkiewicz artery. The artery of Adamkiewicz is identifiable in about 80% of patients, the laterality of the arteries originating from the left side in 95% of patients and between T9 and T12 in 90% of patients. Identification of this artery provides useful information for reconstruction of intercostal arteries and the lumbar artery in TAAA as well as enabling surgery time to be reduced.
In summary, previous descending thoracic aortic aneurysm repair did not adversely affect the outcome of TAAA repair. Therefore, we recommend computed tomography of the chest and abdomen once or twice a year for follow-up in patients who have undergone initial aortic aneurysm repair.
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References
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Abstract
Introduction
