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Ann Thorac Surg 2002;74:S1800-S1802
© 2002 The Society of Thoracic Surgeons
a Division of Cardiovascular and Thoracic Surgery, Missouri Baptist Medical Center, St. Louis, Missouri, USA
* Address reprint requests to Dr Kouchoukos, Cardiac, Thoracic and Vascular Surgery, Inc., 3009 North Ballas Rd, Suite 266C, St. Louis, MO 63348, USA
e-mail: ntkouch{at}aol.com
Presented at the Aortic Surgery Symposium VIII, May 2–3, 2002, New York, NY.
Abstract
BACKGROUND: Management of the enlarged, chronically dissected aorta after previous repair of acute ascending aortic dissection or after a previous cardiac operation may present a formidable technical challenge and the optimal method of management is not clearly established.
METHODS: Twenty-one patients with chronic type A aortic dissection (mean age 57 years) underwent resection of the ascending aorta, the aortic arch, and varying segments of the descending thoracic aorta. Single-stage replacement with perfusion of the aortic arch first to minimize the duration of brain ischemia and a bilateral anterior thoracotomy (clamshell) incision were used. Fourteen patients had undergone previous repair of acute type A dissection. Seven patients had type A dissection after aortic valve replacement (3 patients) or coronary artery bypass (4 patients). Marked enlargement of the aorta distal to the left subclavian artery precluded a two-stage repair. The mean interval between the initial and reoperative procedures was 69 months (range, 5 to 249).
RESULTS: There was 1 (4.8%) hospital death. Four patients required reoperation for bleeding. One patient required a right ventricular assist device that was successfully removed. Ten patients required assisted ventilation for more than 48 hours. All were successfully weaned from ventilatory support. No patient had a stroke or other adverse neurologic outcome. There has been 1 late death (mean follow-up 2 years).
CONCLUSIONS: 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 that requires reoperation can occur in as many as 30% of patients [1]. Aortic dissection can occur after aortic valve replacement or coronary artery bypass grafting and may also result in dilatation of the dissected aorta that requires reoperation [2].
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. Some of these patients will also require concomitant treatment of enlarged or dissected aortic sinuses, aortic regurgitation, and coronary artery disease.
We have used a single-stage reoperative procedure in 21 patients with chronic type A aortic dissection who had enlargement of most or all of the remaining thoracic aorta. We used a bilateral anterior thoracotomy approach with tranverse sternotomy to facilitate exposure of the dilated aortic segments and the aortic root, the arch-first technique to minimize the duration of hypothermic circulatory arrest, and intermittent retrograde brain perfusion [3].
Patients and methods
Patient characteristics
Between November 1997 and March 2002, 21 patients with chronic type A 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 57 years (range 30 to 81 years) and 14 were men. Fourteen patients had previously undergone repair of acute type A aortic dissection. Seven patients (4 who had coronary artery bypass grafting and 3 who had aortic valve replacement) had type A dissection that occurred during or after these procedures. Three of the 21 patients had Marfan’s syndrome. The mean interval between the initial and the reoperative procedure was 69 months (range, 5 to 249).
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 12 patients. The dissection extended into the abdominal aorta in 19 of the 21 patients.
Operative technique
The procedure used in all 21 patients has been described previously [3]. The chest is entered through a bilateral anterior thoracotomy in the fourth intercostal space. A femoral or the right axillary artery is used for arterial return. A long cannula is inserted into a femoral vein and positioned in the right atrium. A second venous cannula is placed in the superior vena cava and cardiopulmonary bypass (CPB) is established.
During cooling the ascending aorta and aortic arch are mobilized. The left phrenic and left vagus nerves are encircled as a pedicle and protected. When adequate cooling is achieved circulatory arrest is established. The ascending aorta is incised and a cuff of aortic tissue surrounding the brachiocephalic arteries is prepared. The descending thoracic aorta is incised and the aortic graft, to which a 10 mm graft has been attached, is positioned in the aortic arch with the 10 mm graft opposite the site where the aortic graft will be attached to the brachiocephalic arteries. The distal portion of the graft is passed into the left side of the chest through the opened aorta beneath the phrenic and vagus nerves.
As the anastomosis to the brachiocephalic arteries is being completed, cold oxygenated blood is infused into the superior vena cava to evacuate air and debris. A clamp is placed on the aortic graft just distal to the left subclavian artery. Using a second arterial line from the pump-oxygenator that has been connected to the 10 mm graft, air is evacuated from the graft. The aortic graft is then clamped just proximal to the innominate artery and flow to the brachiocephalic arteries is established at a rate of 800 to 1,200 mL/min at a temperature of 20°C to 22°C. Arterial pressure in the upper body is monitored during the hypothermic perfusion.
The descending thoracic aorta is transected at the appropriate level. A portion of the septum between the true and false lumens is excised and the distal end of the aortic graft is anastomosed to the outer rim of the aorta. After removal of air the clamp on the aortic graft distal to the left subclavian artery is removed and antegrade flow is established to the lower body. Rewarming is begun at this time.
During rewarming, the proximal end of the aortic graft is anastomosed to the previously inserted ascending aortic graft. If aortic root or aortic valve replacement is required, it is performed at this time. Coronary artery bypass grafting if indicated is also performed. When rewarming is completed CPB is discontinued.
The extent of descending thoracic aortic replacement and the concomitant procedures performed in the 21 patients are shown in Table 1. The perfusion data are shown in Table 2. The duration of circulatory arrest averaged 42 minutes. It exceeded 50 minutes in only 4 patients and did not exceed 60 minutes in any patient.
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Results
Mortality
There was 1 hospital death (4.8%; 70% confidence limits, 0% to 9.6%). 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. There was 1 late death as a result of sepsis and metastatic carcinoma of the prostate in the follow-up period, which extends to 52 months (mean 24).
In our total experience with this technique for patients with chronic dissection or extensive degenerative aortic disease, there have been 2 (6.1%) hospital deaths among 33 patients.
Morbidity
Four patients (19%) required reoperation for bleeding. Ten patients (48%) required ventilatory support for more than 48 hours and 3 patients (19%) required temporary tracheostomy. The mean duration of ventilatory support was 7.4 days (median 2.5, range 1 to 42). All patients were weaned from mechanical ventilation.
Inotropic support with more than 5 µg · kg-1 · min-1 of dobutamine for more than 24 hours was required in 4 patients (19%). One patient required intraoperative insertion of a right ventricular assist device (centrifugal pump) for right-side 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 patients (14%). All had return of the blood urea nitrogen and creatinine to base line levels before discharge from the hospital. One patient required a femorofemoral 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 [4]. No patient sustained a stroke. Transient neurologic dysfunction occurred in 9 (43%) patients, and resolved completely in all. No patient had evidence for spinal cord ischemic injury. No patient developed permanent left vocal cord paralysis.
There were no deep wound infections. The mean duration of the postoperative hospital stay was 19 days (median 12, range 8 to 66). At a mean follow-up interval of 25 months all 19 surviving patients are alive and well (New York Heart Association class I, 14 patients, and NYHA class II, 5 patients). All patients have been evaluated with computed tomography at 6-month intervals. One patient underwent successful reoperation for a false aneurysm resulting from an erosion of the graft. No patient has required reoperation for proximal or distal aortic disease.
Comment
We believe that the technique we have described offers certain advantages over a median sternotomy approach or staged techniques in patients with chronic type A dissection in whom most or all of the remaining thoracic aorta is involved, particularly 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. Unless coronary artery bypass grafting is 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 three 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. The duration of circulatory arrest did not exceed 60 minutes in any patient and exceeded 50 minutes in only 4 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 sustained a permanent neurologic deficit.
Because of the small number of patients a strict comparison of our technique with other surgical approaches is not possible. It is not known whether use of a median sternotomy incision or a median sternotomy with a T extension into the left chest in comparable patients would be associated with less mortality and morbidity. However, our previous experience with these techniques would suggest that this is not the case. These approaches do not provide adequate exposure of the distal half of the descending thoracic aorta. They do not permit easy placement of a clamp on the aortic graft distal to the left subclavian artery, which is necessary to perfuse the brachiocephalic arteries before performing the distal aortic anastomosis. The bilateral anterior thoracotomy incision provides sufficient exposure to permit these maneuvers without excessive manipulation of the left lung, which should be avoided in fully heparinized patients to minimize intraparenchymal hemorrhage.
A two-stage approach such as the elephant trunk procedure could also be utilized as an alternative to the technique we have described. However, the large size (>4.5 to 5 cm) of the dissected proximal descending thoracic aorta that was present in these patients would, we believe, preclude a safe anastomosis to an aortic graft. It is of interest that Safi and colleagues [5] reported an interval mortality between the first and second stages of the elephant trunk procedure of 3.6% (4 of 111 patients) and that 3 of the 4 deaths were due to aortic rupture. In addition, there were 13 deaths among 43 patients who did not return for the second-stage procedure. Four of these 13 deaths were also due to aortic rupture. The anastomosis of the elephant trunk to the proximal descending thoracic aorta may be at risk for rupture if the aorta is large or dissected in this area.
In summary, our extended experience with this technique in patients who require reoperation for chronic type A aortic dissection suggests that 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.
References
This article has been cited by other articles:
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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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