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J Thorac Cardiovasc Surg 2001;122:578-582
© 2001 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease (ACD) |
From the Division of Cardiovascular and Thoracic Surgery, Missouri Baptist Medical Center, St Louis, Mo.
Received for publication Jan 16, 2001. Revisions requested Feb 13, 2001; revisions received March 1, 2001. Accepted for publication March 8, 2001. Address for reprints: Nicholas T. Kouchoukos, MD, 3009 N Ballas Rd, Suite 266C, St Louis, MO 63131 (E-mail NTKouch{at}aol.com).
Abstract
Objective: Management of the enlarged, chronically dissected aorta after previous repair of acute aortic dissection or after a previous cardiac operation may present a formidable technical challenge. Marked enlargement of the proximal descending thoracic aorta precludes safe use of staged procedures, including the elephant trunk technique.
Methods: Sixteen patients with chronic type A aortic dissection (mean age, 56 years) underwent resection of the ascending aorta, the aortic arch, and varying segments of the descending thoracic aorta. We used single-stage replacement, with perfusion of the aortic arch first to minimize the duration of brain ischemia, with a bilateral anterior thoracotomy (clamshell) incision. Eleven patients had undergone previous repair of acute type A dissection. Five patients had type A dissection after aortic valve replacement (2 patients) and coronary artery bypass (3 patients). Marked enlargement of the aorta distal to the left subclavian artery precluded a 2-stage repair. The mean interval between the initial and reoperative procedures was 62 months (range, 5-137 months).
Results: There was 1 (6.2%; 70% confidence limits, 0.3%-24.7%) hospital death. Four patients required reoperation for bleeding. One patient required a right ventricular assist device that was successfully removed. Six patients required assisted ventilation for more than 72 hours, and 3 patients required a tracheostomy. All were successfully weaned from ventilatory support. No patient had a stroke or other adverse neurologic outcome.
Conclusion: The single-stage, arch-first replacement technique is a safe and effective procedure for patients who require extensive reoperations for chronic expanding type A dissection.
After successful surgical treatment of acute type A aortic dissection with graft replacement of only the ascending aorta, dilatation of the aorta distal to the site of graft insertion requiring reoperation can occur in up to 30% of patients.
1-4 Some of these patients may also have aneurysms, dissection of the aortic sinuses, and aortic valve regurgitation. 5-7 Unrecognized aortic dissection can occur after aortic valve replacement or coronary artery bypass grafting and may also result in dilatation of the dissected aorta. 8,9
The optimal surgical treatment of patients with the above conditions who have substantial enlargement of the remaining ascending aorta, the aortic arch, and part or all of the descending thoracic aorta is not clearly established. 10-13 Some of these patients will also require concomitant treatment of enlarged or dissected aortic sinuses, aortic regurgitation, and coronary artery disease.
We present our experience with a single-stage reoperative procedure in 16 patients with chronic type A aortic dissection who had extensive enlargement of most or all of the remaining thoracic aorta. We used a bilateral anterior thoracotomy approach with transverse sternotomy to facilitate exposure of the dilated aortic segments and the aortic root and the arch-first technique to minimize the duration of hypothermic circulatory arrest and retrograde perfusion. 14
Methods
Patient characteristics
Between November 1997 and October 2000, 16 patients with chronic type A aortic dissection underwent single-stage resection of the ascending aorta, the aortic arch, and varying lengths of the descending thoracic aorta. The mean age of the patients was 56 years (range, 30-81 years), and 13 were men. Eleven patients had previously undergone repair of acute type A aortic dissection. Five patients (3 who had coronary artery bypass grafting and 2 who had aortic valve replacement) had a type A dissection during or after these procedures. Three of the 16 patients had Marfan syndrome. The mean interval between the initial and the reoperative procedures was 62 months (range, 5-137 months).
Among the 11 patients with previous acute type A dissection, 6 had graft replacement of the ascending aorta as the initial procedure (2 isolated, 2 with aortic valve resuspension, and 2 with aortic valve replacement), and 5 had replacement of the ascending aorta and the aortic valve with a composite graft. The indications for reoperation were progressive enlargement of the involved aortic segment documented by computed tomography or magnetic resonance imaging in all patients and the presence of symptoms (chest pain, back pain, and congestive heart failure) in 9 patients. All patients underwent preoperative cardiac catheterization and chest and abdominal computed tomography or magnetic resonance imaging (Figure 1). Aortography was performed in 13 patients (Figure 2). The dissection extended into the abdominal aorta in 15 of the 16 patients.
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14 In brief, the chest is entered through a bilateral anterior thoracotomy in the fourth intercostal space. The pericardium is incised over the right atrium, and unless coronary artery bypass grafting will be performed, it is mobilized only enough to permit separate cannulation of the superior and inferior venae cavae, insertion of a venting catheter through the right inferior pulmonary vein (or alternatively through the left superior pulmonary vein), and placement of a cannula into the coronary sinus for delivery of cardioplegic solution. Arterial return is established through a common femoral artery or the right axillary artery. Intraoperative transesophageal echocardiography is used routinely.
Cardiopulmonary bypass is established, and cooling is initiated. During cooling, the ascending aorta is freed from the undersurface of the sternum. If clamping of the ascending aorta is possible and there is no aortic regurgitation, cold cardioplegic solution is infused into the aortic root through a cannula at 15- to 20-minute intervals. The left lung is collapsed, and the inferior pulmonary ligament is divided. The left phrenic and left vagus nerves are identified and isolated as a pedicle with a vascular tape. When coronary bypass grafting is required, the distal anastomoses can be performed during the period of cooling. When the appropriate nasopharyngeal and bladder temperatures are reached and the electroencephalogram becomes isoelectric, 14 the head is packed in ice and circulatory arrest is established. The ascending aorta is incised, and a cuff of aortic tissue containing the brachiocephalic vessels is prepared. The descending thoracic aorta is incised beyond the left vagus nerve, and the aortic graft, to which a 10-mm graft has been attached, is passed into the opened arch and down into the descending thoracic aorta. The 10-mm graft is positioned opposite the site where the anastomosis to the brachiocephalic vessels will be performed, an opening is made in the graft at the site of the arch vessels, and the aortic tissue surrounding the arch vessels is sutured to the graft. As this anastomosis is being completed, cold (20°C-22°C) oxygenated blood is infused in a retrograde manner into the superior vena caval cannula. 15 The aortic graft is clamped just distal to the arch anastomosis, and the proximal portion of the graft is allowed to fill with blood. Arterial flow is established through a second arterial line from the pump-oxygenator that is connected to the 10-mm graft or through the axillary artery if it is used for arterial return. The aortic graft is then clamped proximal to the arch anastomotic site. Antegrade perfusion of the brachiocephalic vessels is established at a flow rate of 800 to 1200 mL/min and at a temperature of 20°C to 22°C. The anastomosis of the graft to the distal thoracic aorta is then performed during the period of hypothermic low flow by an open technique. If dissection is present at the anastomotic site, a portion of the septum between the true and false aortic lumina is excised to permit perfusion of both channels. Patent intercostal arteries above the sixth intercostal space are ligated. If the resection extends below this level, the distal aorta is beveled to preserve the lower intercostal arteries. When the anastomosis is completed and air has been removed from the graft, the clamp on the aortic graft distal to the aortic arch is removed, and flow is established in the antegrade direction. Rewarming is begun at this time. Aortic valve or root replacement, if indicated, is performed during the period of rewarming. The proximal end of the aortic graft is trimmed and is sutured to the aorta just above the level of the aortic commissures or to the existing ascending or composite aortic graft. Saphenous vein bypass grafts, if present, are anastomosed to the aortic graft. When rewarming is complete, air is removed from the heart, and cardiopulmonary bypass is discontinued.
Extent of resection and concomitant procedures
The remaining dissected ascending aorta, the entire aortic arch, and varying lengths of the descending aorta were resected and replaced in all 16 patients (Table 1). Dissection was present in the remaining descending thoracic and abdominal aorta in 15 of the 16 patients. In these patients the aorta was transected at a level where its diameter did not exceed 3 to 3.5 cm. Four patients had composite graft replacement of the aortic root, 2 had coronary artery bypass grafting, and 1 required mitral valve replacement (Table 1).
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Mortality
There was 1 (6.2%; 70% confidence limits [CL], 0.3%-24.7%) hospital death. A 47-year-old man with previous ascending aortic replacement and aortic valve resuspension for acute type A dissection had biventricular failure postoperatively, as well as acute renal failure requiring dialysis, because of persisting severe aortic regurgitation. He also had progressive enlargement of the residual ascending aorta, the arch, and the descending thoracic aorta. At reoperation 9 months later, composite graft replacement of the aortic root, as well as replacement of the ascending aorta, the aortic arch, and the proximal two thirds of the descending aorta, were performed. After an initially uneventful course that included extubation, he had a cardiac arrest on the eighth postoperative day. At autopsy, the surgical repair was intact. There was severe cardiomegaly and evidence of a recent acute inferior wall myocardial infarction. There was also 1 late death in the follow-up period, which extends to 36 months. This patient had severe aortic regurgitation and congestive failure preoperatively and required aortic root replacement, as well as replacement of the arch and of the proximal one third of the descending thoracic aorta. He died 3 months postoperatively as a result of sepsis and metastatic carcinoma of the prostate.
Morbidity
Four (25%) patients required reoperation for bleeding. The intraoperative mean transfusion requirements were 9.1 units (range, 1-22 units), of packed red cells, 8.8 units (range, 4-23 units) of fresh frozen plasma, 6.8 units (range, 2-16 units) of platelets , and 1 unit (range, 0-4 units) of cryoprecipitate. The postoperative mean transfusion requirements were 4 units (range, 0-15 units) of packed red cells, 1.9 units (range, 0-9 units) of fresh frozen plasma, 0.4 units (range, 0-2 units) of platelets, and no cryoprecipitate.
Nine (56%) patients required ventilatory support for more than 48 hours, and 3 (19%) patients required temporary tracheostomy. The mean duration of ventilatory support was 9.2 days (median, 3 days; range, 1-42 days). All patients were weaned from mechanical ventilation. Left vocal cord paralysis, presumably caused by stretching of the left recurrent laryngeal nerve by the aortic graft, occurred in 3 (19%) patients. This resolved spontaneously in all 3 cases.
Inotropic support with more than 5 µg · kg–1 · min–1 dobutamine for more than 24 hours was required in 4 (25%) patients. One patient required intraoperative insertion of a right ventricular assist device (centrifugal pump) for right heart failure. This was removed successfully on the third postoperative day, and the patient made a full recovery.
Renal failure requiring temporary hemofiltration or hemodialysis occurred in 3 (19%) patients. All had return of blood urea nitrogen and creatinine levels to baseline levels before discharge from the hospital. One patient required a femoro-femoral bypass graft for acute occlusion of the left external iliac artery on the third postoperative day.
Stroke and transient neurologic dysfunction were evaluated according to the classification of Ergin and colleagues. 16 No patient had a stroke. Transient neurologic dysfunction occurred in 6 (38%) patients and resolved completely in all. No patient had evidence for spinal cord ischemic injury.
There were no deep wound infections. The mean duration of the postoperative hospital stay was 21 days (median, 13 days; range, 8-66 days). At a mean follow-up interval of 13 months, all 14 surviving patients are alive and well (New York Heart Association class I, 10 patients; New York Heart Association class II, 4 patients). All patients have been evaluated with computed tomography at 6-month intervals, and no patient has required reoperation for proximal or distal aortic disease.
Discussion
After repair of acute type A aortic dissection by graft replacement of the ascending aorta and aortic valve repair or replacement (a standard technique), the false lumen distal to the aortic graft remains patent in 70% to 100% of patients. 4,17,18 Aneurysmal dilatation of the residual dissected aorta may also occur, particularly if the intimal tear involved the aortic arch at the time of the initial operation. 19,20 Periodic follow-up after repair of acute type A aortic dissection has shown that reoperation for distal aortic disease is required in 20% to 30% of patients within the first 5 to 7 years. 21-24 The need for reoperation is higher in patients with Marfan syndrome. 25-27
Replacement of the ascending aorta and the entire aortic arch at the initial operation for acute type A dissection may prevent or reduce the prevalence of aneurysmal dilatation of the remaining dissected aorta and the need for subsequent operations on the distal aorta. 28-30 However, the operative mortality for these more extensive procedures may be higher than that for the conventional operation. 28,31 Staged procedures for the management of extensive disease of the remaining thoracic aorta, including the use of the elephant trunk technique, have been successfully used to treat the conditions we have described. 13,32 Although these are useful techniques, marked aneurysmal dilatation of the proximal descending thoracic aorta, the usual site for attachment of the aortic graft, is often present in the setting of chronic aortic dissection and may preclude safe anastomosis of a graft to the aorta in this area. Furthermore, the aggregate mortality and morbidity for the staged procedure may be substantial. 13,32 We use the single-stage technique in patients with chronic dissection when the diameter of the aorta just distal to the left subclavian artery exceeds 4.5 to 5 cm and the aneurysmal dilatation does not extend into the abdominal aorta.
The technique we have described offers certain advantages over the staged techniques in patients with chronic type A dissection, in whom most or all of the remaining thoracic aorta is involved, particularly in those in whom the proximal descending thoracic aorta is substantially enlarged. The transverse bilateral anterior thoracotomy incision provides excellent exposure of the heart, the brachiocephalic arteries, the left phrenic and left vagus nerves, and the entire descending thoracic aorta. If coronary artery bypass grafting is not required, mobilization of the heart from the pericardium is necessary only on the lateral surface of the right atrium and the adjacent interatrial groove. If coronary artery bypass grafting is necessary, exposure of the 3 major coronary arterial systems is satisfactory. The aortic root is also accessible if aortic valve or aortic root replacement is indicated.
Anastomosis of the aortic graft to the brachiocephalic arteries before performance of the distal aortic anastomosis reduces the duration of brain ischemia. In our series the duration of circulatory arrest did not exceed 60 minutes in any patient and exceeded 50 minutes in only 3 patients. Retrograde brain perfusion to facilitate evacuation of air and debris from the cerebral circulation was used in all patients. This was easily accomplished by use of a cannula in the superior vena cava. No patient had a permanent neurologic deficit.
Nine of the 16 patients required prolonged ventilatory support. This may have resulted, in part, from manipulation of the left lung, which was required for exposure of the middle and distal portions of the descending thoracic aorta. Maintaining the lung in a totally collapsed state during the entire procedure will minimize injury, and this was attempted in all patients.
In our total experience with this technique, which includes patients with extensive thoracic aortic disease but without dissection, there have been 2 (8%) hospital deaths among 25 patients.
The present study documents our experience with a small number of patients and a short follow-up period. However, the low early mortality and the absence of major morbidity suggest that the technique is a suitable alternative to a staged approach for patients with chronic type A aortic dissection and aneurysmal degeneration that is confined to the thoracic aorta. It may represent the optimal method of management for patients in whom substantial enlargement of the proximal descending thoracic aorta precludes safe suturing of a prosthetic graft to this segment of the aorta. It is our preferred method of management. A larger number of patients and longer follow-up will be required to confirm these initial results.
References
This article has been cited by other articles:
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  M. Karck and H. Kamiya Progress of the treatment for extended aortic aneurysms; is the frozen elephant trunk technique the next standard in the treatment of complex aortic disease including the arch? Eur. J. Cardiothorac. Surg., June 1, 2008; 33(6): 1007 - 1013. [Abstract] [Full Text] [PDF]
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 J. P. Schwartz, M. Bakhos, A. Patel, S. Botkin, and S. Neragi-Miandoab Repair of aortic arch and the impact of cross-clamping time, New York Heart Association stage, circulatory arrest time, and age on operative outcome Interactive CardioVascular and Thoracic Surgery, June 1, 2008; 7(3): 425 - 429. [Abstract] [Full Text] [PDF]
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 T. B. Reece, G. R. Green, and I. L. Kron Aortic Dissection Card. Surg. Adult, January 1, 2008; 3(2008): 1195 - 1222. [Full Text]
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 M. A. Pichlmaier, O. E. Teebken, H. Baraki, and A. Haverich The frozen elephant trunk technique MMCTS, March 29, 2007; 2007(0329): 1990. [Abstract] [Full Text] [PDF]
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M. Gorlitzer, W. Wislocki, J. Meinhart, and M. Grabenwoger Treatment of chronic aortic type A dissection with a new designed hybridprosthesis Eur. J. Cardiothorac. Surg., February 1, 2007; 31(2): 315 - 317. [Abstract] [Full Text] [PDF]
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M. Karck, A. Chavan, N. Khaladj, H. Friedrich, C. Hagl, and A. Haverich The frozen elephant trunk technique for the treatment of extensive thoracic aortic aneurysms: operative results and follow-up Eur. J. Cardiothorac. Surg., August 1, 2005; 28(2): 286 - 290. [Abstract] [Full Text] [PDF]
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M. Sasaki, A. Usui, M. Yoshikawa, T. Akita, and Y. Ueda Arch-first technique performed under hypothermic circulatory arrest with retrograde cerebral perfusion improves neurological outcomes for total arch replacement Eur. J. Cardiothorac. Surg., May 1, 2005; 27(5): 821 - 825. [Abstract] [Full Text] [PDF]
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M. Doss, T. Woehleke, J. P. Wood, S. Martens, G. W. Greinecker, and A. Moritz The clamshell approach for the treatment of extensive thoracic aortic disease J. Thorac. Cardiovasc. Surg., September 1, 2003; 126(3): 814 - 817. [Abstract] [Full Text] [PDF]
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T. Kazui, K. Yamashita, N. Washiyama, H. Terada, A. H. M. Bashar, T. Suzuki, and K. Ohkura Impact of an aggressive surgical approach on surgical outcome in type A aortic dissection Ann. Thorac. Surg., November 1, 2002; 74(5): S1844 - 1847. [Abstract] [Full Text] [PDF]
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N. T. Kouchoukos, P. Masetti, and C. K. Rokkas Single-stage replacement of the thoracic aorta Ann. Thorac. Surg., October 1, 2002; 74(4): 1292 - 1292. [Full Text] [PDF]
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