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Total arch graft replacement in patients with acute type a aortic dissection
Total Arch Graft Replacement in Patients With Acute Type A Aortic Dissection Teruhisa Kazui, MO, Nozomu Kimura, MO, Osamu Yamada, MO, and Sakuzo Komatsu, MO Second Department of Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
Treatment of acute type A aortic dissection with emergency total aortic arch graft replacement remains controversial. Between December 1988 and July 1993, 30 patients with this fatal disease underwent graft replacement of both the ascending aorta and total aortic arch on an emergency basis. All operations were performed with the aid of extracorporeal circulation, blood cardioplegia, selective cerebral perfusion, and open distal anastomosis. The overall early mortality rate was 23.3% (7 patients), but that in patients with complications with shock and
renal/mesenteric ischemia was 57% and 66.7%, respectively. On the other hand, the mortality rate in the 23 patients (77%) in whom neither of these two risk factors was present was low (8.7%). The overall 4-year survival rate was 66.5% ± 8.7%, and that for patients without these two risk factors was 87.0% ± 7.0%. The present data suggest that simultaneous total arch replacement may be justified in selected patients with acute type A aortic dissection. (Ann Thorae Surg 1994;58:1462-8)
I
Material and Methods
t generally is accepted that patients with acute type A aortic dissection require emergency surgical intervention. Ascending aorta repair alone is the procedure of choice in most patients in whom the primary intimal tear is located in the ascending aorta. However, aortic arch dissection in which the intimal tear is located at the aortic arch is present in 10% to 20% of patients, and there is very little agreement as to the appropriate clinical strategy to be used in these cases. Although medical management has been advocated [1], emergency operation is necessary to save the life of patients during the acute stage because of the unfavorable medical outcome [2]. During emergency operation, ascending aorta replacement without resection of the arch tear has been performed in many centers to prevent the fatal cardiac tamponade [3,4]. However, with recent advances in various cerebral protection methods during aortic arch repair, aggressive aortic arch repair is increasingly performed [5-11]. The operative technique used in aortic arch repair varies with the institution and ranges from limited partial arch replacement to extended total arch replacement. For the last 7 years, we have used selective cerebral perfusion (SCP) for prevention of cerebral ischemia in the treatment of more than 100 patients with aortic arch aneurysm, with satisfactory results [12]. We describe herein our experience with simultaneous total arch replacement for acute type A aortic dissection, discuss the indications for this surgical procedure, and describe the operative technique using SCP and the outcome. Accepted for publication May 5,1994. Address reprint requests to Dr Kazui, Second Department of Surgery, Sapporo Medical University School of Medicine, South 1, West 17,Chuo-ku, Sapporo 060, Japan.
© 1994 by The Society of Thoracic Surgeons
Patient Profile The subjects were 30 consecutive patients who underwent graft replacement of the ascending aorta and total aortic arch for acute type A aortic dissection during the period between December 1988 and July 1993. Fifteen patients who underwent limited partial arch replacement during the same period are excluded from this study. Subjects ranged in age from 32 to 71 years, with a mean age (::!:: standard deviation) of 55.6 ::!:: 10.1 years. There were 20 men and 10 women. The preoperative complications included shock state requiring cardiopulmonary resuscitation in 7 patients (23%), cardiac tamponade in 12 (40%), rupture of the left pleural cavity in 1 (3%), aortic regurgitation in 17 (56%) including 5 with annuloaortic ectasia, myocardial ischemia in 2 (6%), transient cerebral ischemia in 507%), paraplegia in 1 (3%), renal/mesenteric ischemia in 6 (20%), leg ischemia in 7 (23%), and ischemia of two or more organs in 5 07%) (including transient cerebral ischemia and renal/mesenteric ischemia in 1 (3%), renal/ mesenteric ischemia and leg ischemia in 3 00%), and renal/mesenteric ischemia and leg ischemia and paraplegia in 1 (3%). Classic Marfan's syndrome was present in 3 patients. Fourteen (47%) of these 30 patients underwent preoperative aortography to confirm the diagnosis, and the remaining patients had undergone either computed tomography performed at another hospital or echocardiography, including transesophageal color Doppler technique after tracheal intubation in the operating room because of their critical condition. Assessment of both the preoperative diagnostic procedures and intraoperative findings indicated that a primary intimal tear was located at the ascending aorta in 7 patients, from the ascending aorta to the aortic arch in 6, at the aortic arch in 9, and at the 0003-4975/94/$7.00
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KAZUI ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
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proximal descending aorta in 5. In the remaining 3 patients, no intimal tear was found at the ascending aorta, aortic arch or proximal portion of the descending aorta during the operation. All operations were performed on an emergency basis during the acute stage within 2 weeks after the onset of symptoms. The average interval between onset and operation was 2.9 ± 2.7 days.
Operative Techniques In all patients, a median sternotomy and left supraclavicular incision were made to expose the heart, ascending aorta, aortic arch, and arch vessels. After systemic heparinization, extracorporeal circulation was instituted with the arterial return cannula placed in a femoral artery and a single two-stage cannula for venous drainage in the right atrium. The left side of the heart was vented through the right superior pulmonary vein. The ascending aorta was cross-clamped under electrical fibrillation; when the patient's temperature reached 32°C, the aorta was opened longitudinally and blood cardioplegia was infused directly into both coronary ostia. During cooling with extracorporeal circulation, aortic valve resuspension was performed in 12 patients with acute aortic regurgitation, and composite graft replacement with coronary reimplantation was performed in 5 patients with annuloaortic ectasia. In one of the latter patients, classic Bentall operation was performed as the operative technique for coronary reimplantation, while the 4 patients treated later in the period underwent Carrel's button technique. In the latter technique, the buttons of aorta from which the coronary arteries arose were excised, reinforced with a ring-shaped Teflon felt on the outside of the aorta and sewn to the side hole of the graft using a running 4-0 polypropylene suture. In 2 patients in whom the severe dissection involving the right coronary ostium was present, vein bypass grafting to the distal right coronary artery after ligation of the coronary ostium was performed. In another patient with significant stenosis of the left anterior descending artery, vein bypass grafting to this coronary artery was performed. After the aortic valve repair and distal graft anastomosis of the coronary artery bypass grafting, the ascending aorta and the aortic arch were reconstructed. Selective cerebral perfusion was used in all patients to prevent cerebral ischemia during the aortic arch repair. The SCP procedure used has been reported in detail elsewhere [13]. The two operative techniques used for aortic arch reconstruction are illustrated in Figure 1 and described below. "EN-BLOC" REPAIR TECHNIQUE. This operative technique was used in the first 4 patients treated in the study period. The aorta was opened, and the proximal false lumen was obliterated with two Teflon strips. When the rectal temperature dropped to 22°C, SCP cannulas were inserted into the innominate and left common carotid arteries. The route of cannula insertion depended on the degree of arch vessel involvement. After systemic circulation was arrested and the aorta was opened, the cannulas were inserted directly into the distal portion of the vessels when the vessels were
Fig 1. Surgical techniques used in graft replacement of both the ascending aorta and the total aorticarch, performed in 30 patients.
not involved with the dissection, and internally through the aortic lumen when the vessels were severely involved. Blood then was perfused into both arteries at the rate of 10 mL· kg-I. min- 1 for both vessels, using a single roller pump separated from the systemic circulation. With the distal end of the aortic arch left open, distal graft anastomosis and aortic arch reconstruction were performed. During this open aortic anastomosis, blood perfusion to the lower half of the body from the femoral artery was arrested or reduced to approximately 500 mL/min. Blood was aspirated from the operative field and returned to the cardiopulmonary bypass circuit. The distal false lumen at the site of the proximal descending aorta just below the junction with the left subclavian artery was obliterated in a similar fashion. A soft woven Dacron graft of low porosity was then anastomosed to the descending aorta using a continuous 3-0 polypropylene suture. The orifices of the arch vessels at the cuff remaining after obliteration of the false lumen in the aortic arch were anastomosed in an end-to-side fashion to the side hole on the graft. Following reconstruction of the arch vessels, the graft was cross-clamped proximally, the SCP cannulas were removed, and cerebral circulation was started and rewarmed by extracorporeal circulation. The proximal end of the graft was then anastomosed to the proximal stump of the ascending aorta using a continuous 3-0 polypropylene suture. Immediately before completion of the anastomosis, air was evacuated from the graft, and coronary circulation was started. Finally, the graft was wrapped with the aneurysmal wall. This operative procedure with "nonwrapping technique" was used in the last 26
SEPARATED GRAFT TECHNIQUE.
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KAZUI ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
patients treated in the study period. The ascending aorta just above the aortic commissures was completely transected, and the proximal false lumen was obliterated with two Teflon strips. When the patient's temperature cooled to 22°C during extracorporeal circulation, the aorta was declamped and the systemic circulation from the femoral artery was arrested. Selective cerebral perfusion cannulas were inserted directly into the innominate and left common carotid arteries through the aortic lumen internally, and SCP was started. Open aortic anastomosis was then performed. The descending aorta just distal to the origin of the left subclavian artery was transected circumferentially, and the distal false lumen was obliterated in a similar fashion. In patients with DeBakey type retrograde IIIb dissection, the descending aorta distal to the site of intimal tear was transected. A graft provided with three limbs was then anastomosed to the distal stump of the descending aorta using a continuous 3-0 polypropylene suture. After completion of the distal graft anastomosis, the proximal graft was cross-clamped, and recirculation and rewarming with extracorporeal circulation were started at the graft of the left subclavian artery or the fourth graft attached to the main graft, rather than at the femoral cannula. During the rewarming period, the proximal graft was anastomosed to the proximal stump of the ascending aorta using a continuous 3-0 polypropylene suture. Before completion of the proximal anastomosis, the air was evacuated from the graft and coronary circulation was started. The three limbs of the graft were then anastomosed in succession to, respectively, the innominate, left common carotid, and left subclavian arteries using a running 4-0 polypropylene suture. Each SCP cannula was removed immediately before completion of the respective arch vessel anastomosis. In most patients, the heart was defibrillated with direct-current countershock during the arch vessel reconstruction. In no patient was the graft wrapped with aneurysmal wall to obtain hemostasis.
Statistical Methods The continuous data in this article are expressed as the mean ± standard deviation. Differences between categoric parameters were assessed by >1 test or Student's t test; a p value of less than 0.05 was considered to be statistically significant. The actuarial survival rates were calculated by the Kaplan-Meier method (with variability expressed as standard error of the estimate) and compared using the log rank test.
Results Early Mortality The overall 30-day mortality rate was 23.3% (7 of the 30 patients). One patient died in the operating room. Table 1 shows the relationship of various preoperative and perioperative variables to the early postoperative mortality rate. This rate was 57.1% in patients with the preoperative complication of shock and 66.7% those with renal/ mesenteric ischemia; this rate was significantly higher than that in patients without the respective factor (both p <
Table 1. Preoperative and Perioperative Variables and Early Mortality Rate Earll; Morta ity Variable Total patients Sex Male Female Age (y) 24-35 36-45 46-55 56-65 66-75
No. of Patients
No. of Patients
%
30
7
23.3
20 10
4 3
20 30
1 3 8 12 6
0 0 2 4 1
0 0 25 33.3 16.7
NS NS
Interval between onset and operation (h) 0-24 25-48 49-72 73-108 109-336
Site of intimal tear AscAo Aso AD-Arch Arch Des Ao Unknown Shock (+) (-)
NS 10 8 6 4 2
2 1 2 2 0
20.0 12.5 33.3 50.0 0
7 6 9 5 3
3 2 0 1 1
42.8 33.3 0 20.0 33.3
7 23
4 3
57.1 13.0
12 18
4 3
33.3 16.7
1 29
0 7
0 29.1
17 13
3 4
17.6 30.0
2 28
1 6
50.0 21.4
5 25
0 7
0 28
1 29
1 6
100 20.7
6 24
4 3
66.7 12.5
7 23
3 4
42.9 17.4
NS
<0.05
Cardiac tamponade (+) (-)
NS
Pleural rupture (+) (-)
NS
AR (+) (-)
NS
Myocardial ischemia (+) (-)
NS
Cerebral ischemia (+) (-)
NS
Paraplegia (+) (-)
NS
Renal! mesenteric ischemia (+) (-)
Leg ischemia (+) (-)
<0.05
NS NS
Two or more organs ischemia (+) (-)
p Value
5 25
3 4
60 16.0
Continued on next page
KAZU1 ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
Ann Thorac Surg 1994;58:1462-8
Causes of Early Mortality
Table 1. Continued Early Mortality Variable
No. of Patients
No. of Patients
%
7 23
5 2
71.4 8.7
12 18
3 4
25.0 22.2
5 25
0 7
0 28.0
3 27
1 6
33.3 22.2
NS
A/V resuspension (+) (-)
NS
Composite graft (+) (-)
NS
CABG (+) (-)
Arch reconstruction En bloc Separated graft Graft replacement Inclusion technique Nonwrapping technique
p Value <0.01
Shock + renal/mesenteric ischemia (+) (-)
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NS 4 26
0 7
0 26.9
4 26
0 17
0 26.9
NS
AR = aortic regurgitation; Asc Ao = ascending aorta; A/V = aortic Des Ao = descendvalve; CABG = coronary artery bypass grafting; ing aorta; NS = not significant.
The patient who died in the operating room had distal fenestration at the site of descending aortic anastomosis; the cause of death was rupture of the descending aorta. In 1 patient each, the cause of early death was hemorrhage at the anastomosed site of the aorta secondary to postoperative mediastinitis on the fifteenth postoperative day, multiple organ failure on the eighteenth postoperative day in a patient with preoperative paraplegia, renal/mesenteric ischemia and leg ischemia, abdominal aortic rupture into the retroperitoneal cavity on the third postoperative day, and low cardiac output syndrome in a patient requiring intraaortic balloon pump and a left ventricular assist device on the thirteenth postoperative day. The remaining 2 patients died of respiratory failure on the fourteenth and twenty-fourth postoperative days, respectively.
Extracorporeal Circulation Data The data concerning extracorporeal circulation in the surviving patients in en bloc repair and separated graft groups are compared in Table 2. Total pump time, cardiac ischemia time, SCP time, and open distal anastomosis time in the en bloc repair group were significantly longer than those in the separated graft group.
Late Survival
0.05). Moreover, in the 7 patients (23%) with both of these factors, the early mortality rate was 71.4% (high-risk group). On the other hand, in the 23 patients (77%) in whom both of these factors were absent, the early mortality rate was 8.7% (low-risk group), which was significantly lower than that in the high-risk group (p < 0.01). The early mortality rate was not correlated with patient age, sex, cardiac tamponade, pleural rupture, aortic regurgitation, myocardial ischemia, cerebral ischemia, paraplegia, ischemia of two or more organs, interval between onset and operation, site of intimal tear, aortic valve resuspension, composite graft replacement, coronary artery bypass grafting, or operative technique for arch vessel reconstruction or graft replacement.
The 23 patients who survived the early postoperative period were followed up postoperatively for an average of 1.4 years (range, 4 months to 4 years and 9 months). Figure 2 shows the actuarial survival rate calculated by the Kaplan-Meier method. The overall survival curve reached a plateau 1 year after the operation. The 4-year survival rate for all patients, including those with early mortality, was 66.5% ± 8.7%. All 7 patients in the high-risk group with both preoperative shock and renal/mesenteric ischemia died within 1 year after the operation. The 4-year survival rate for the 23 patients in the low-risk group was 87.0% ± 7.0%, which was significantly higher than that in the high-risk group (p < 0.001). Three patients died during the late postoperative period. The cause of late death in these patients was multiple organ failure in the fourth postoperative month, hepatic failure in the sixth postoperative month, and pneumonitis
Early Morbidity
Table 2. Extracorporeal Circulation Data
All patients who survived the operation (n = 29) regained consciousness postoperatively without any distinct sign of stroke. Postoperative complications included hemorrhage requiring rethoracotomy in 1 patient, pulmonary failure requiring the aid of a respirator for more than 5 days after operation in 19 patients, renal failure indicated by blood urea nitrogen level of more than 70 mg/dL or serum creatinine level of more than 3.0 mg/dL in 7 patients, hepatic failure with total bilirubin level of more than 3.0 mg/dL or glutamic-pyruvic transaminase level of more than 100 units in 3 patients, low cardiac output syndrome requiring intraaortic balloon pump and left ventricular assist device in 1 patient, and multiple organ failure in 5 patients.
Arch Reconstruction
Variable Total pump time (min) Cardiac ischemia time (min) SCP time (min) Open distal anastomosis time (min)
En bloc Repair (n = 4)
Separated graft" (n = 25)
Value
300 :': 65 217 :': 51
215 :': 65 137:': 41
<0.05 <0.01
125 :': 25 100:': 10
96:': 20 51:': 16
<0.05 <0.01
p
a Data for 1 patient who died in the operating room are excluded from this analysis.
SCP = selective cerebral perfusion.
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KAZUl ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
Ann Thorae Surg 1994;58:1462-8
100% , . . , . . . . - - - - - - - - - - - - - - - - - - - - - - ,
h"c
1\ L I
(21)
(21)
(23)
(23)
,
870+70"1.
'--(1·g)--------(i5j-------i9i---------(6i------·-=(~)·,. (20)
I I
0~
~
~
66.5+8.7%
~
I
1 L
- - Overall (n.30) - - - - - _. Low risk group{n=23) - - - High risk group (n.7) P
28.8±17.1'10
(2)----'
I
*
(2) L _ _ ~
I
o
1M
3M
8M
lY
2Y
3Y
4Y
Survival Time
Fig 2. Actuarial survival curvesfor patients who underwent graft replacement of both the ascending aorta and total aortic arch for acute type A aortic dissection by risk group. (Numbers in parentheses indicate number of patients at risk at each interval.)
in the fifth postoperative month. Two former causes of late death were apparently related to preoperative critical condition, including renal/mesenteric ischemia. The other 20 patients are presently leading normal lives. Postoperative aortography and computed tomographic scans performed on 20 patients to evaluate the patency of residual false lumen in the distal descending and abdominal aorta revealed patency of the distal false lumen in the distal aorta in 11 (55%) of these patients. One patient with patent false lumen underwent total graft replacement of the thoracoabdominal aorta for aneurysmal dilation of the false channel in the distal aorta 1 year 5 months postoperatively. This patient was discharged in good condition without paraplegia. Comment There is no disagreement that emergency operation should be performed for acute type A aortic dissection to prevent fatal cardiac tamponade during the acute stage. Because the primary intimal tear is usually located at the ascending aorta in the majority of patients with acute type A aortic dissection, resection of the intimal tear and graft replacement of the ascending aorta are routinely performed. However, there is controversy regarding the operative procedure which should be used in aortic arch dissection in which the primary intimal tear is located at or extends into the aortic arch. The theoretical ideal in such cases would be resection of the aortic arch tear and simultaneous aortic arch repair with graft replacement of the ascending aorta. However, the Stanford group has been reluctant to perform the concomitant aortic arch repair because the operative mortality rate is as high as 50% to 75% in these patients, and because there is no significant difference between groups with and without resection of the intimal tear in the aortic arch in operative or late mortality rate [1, 2]. However, the reoperation rate within 1 year after the operation is as high as 30% in patients without resection of the intimal tear [2]. On the other hand, with the recent improvement of adjunct technique for the prevention of
cerebral ischemia during aortic arch repair, aortic arch reconstruction is increasingly more aggressive, even in emergency operation for acute type A aortic dissection [5-11]. The operative technique used for aortic arch reconstruction ranges from partial to total arch replacement. In most reported operations, the open distal and hemiarch inclusion technique was performed with the aid of hypothermic circulatory arrest [14, 15]. In the patients we treated in the early period, we used this technique for aortic arch dissection in which the intimal tear was located adjacent to the orifice of the innominate artery. The 4-year survival rate for the partial arch group was 73.3% :t 11.4%, which was not statistically significant from 66.5% :t 8.7% for the total arch group. However, since 2 of our patients who underwent partial arch replacement required reoperation for late aneurysmal formation of a residual false lumen in the aortic arch, we now more often perform the more extended total arch replacement. As the technique for graft replacement we used the graft inclusion technique in the early period, but more recently we have used the nonwrapping technique because of the advantage of more accurate graft anastomosis associated with lower risk of hemorrhage in the early postoperative period and of false aneurysm at the site of graft anastomosis in the late period [7]. In addition, as the operative technique for total aortic arch replacement, we now use the separated graft technique instead of en bloc repair technique, not because it allows more precise reconstruction of the arch vessels in patients with the complication of compromise of arch vessels, but also because the total bypass and operation times are reduced. Specifically, the myocardial ischemia time, open distal anastomosis time, and total bypass time in the separated graft group in our study were significantly shorter than those in the en bloc repair group (Table 2). In the former group, after the distal graft anastomosis is completed, recirculation and rewarming with extracorporeal circulation are started through the side graft attached to the main graft, coronary circulation is started following the completion of the proximal graft anastomosis, and the arch vessels are then constructed while the heart is beating. We previously reported that both hypothermic circulatory arrest and SCP are useful methods in the prevention of cerebral ischemia during surgical reconstruction of the aortic arch [16]. Hypothermic circulatory arrest requires no special equipment or cannulation of arch vessels, and the procedure itself is simple, but the time available for cerebral circulatory arrest is restricted; the safe limit is 40 to 60 minutes, even with profound hypothermia [17-19]. Moreover, there are complications of coagulopathy or pulmonary insufficiency related to profound hypothermia, as well as cerebral complication. The incidence of cerebral complication after aortic arch repair in acute aortic dissection is reported to be 7% to 35% [6,8, 14, 15]. On the other hand, SCP presents the advantage of less restricted cerebral protection, and it did not produce any serious postoperative cerebral complications in our patients, even after about 100 minutes of cerebral protection. Therefore, to ensure safety, we used SCP in all patients with acute aortic dissection requiring total arch replace-
Ann Thorac Surg 1994;58:1462-8
ment, because it is difficult to estimate how long before operation the circulation of the aortic arch should be interrupted. One disadvantage of SCP is that it involves a complicated manipulation process. We made an effort to simplify our SCP technique, such as using two-vessel perfusion with a single pump and monitoring the right radial pressure as a measure of perfusion pressure, with satisfactory results. Another disadvantage of SCP is that the arch vessels, which might be involved in the dissection, should be cannulated. In our experience, the cannulas could be inserted easily into the distal portion of the branches when the arch vessels were not involved with dissection, and safely inserted internally if the true lumen could be distinguished from the aortic lumen when the branches to be cannulated were extensively involved. No complications due to cannulation were observed in any of our patients. The SCP cannulas used in our surgical procedure are flexible silicone tubes and do not usually obscure the operative field. When hypothermic circulatory arrest is used, "open distal anastomosis", in which the distal graft anastomosis is performed while the distal aortic arch is left open, is performed [5,8, 14]. This open distal anastomosis presents several advantages, including protection of the fragile aortic wall from damage by the aortic cross-clamp, easy obliteration of the distal false lumen, reinforcement of the aortic wall in a bloodless operative field, and accurate anastomosis of the graft to the distal aorta. For these reasons, we used open distal anastomosis combined with SCP in acute aortic dissection when reconstruction of the aortic arch was required. There was no postoperative paraplegia due to spinal cord ischemia during over 70 minutes of circulatory arrest at the temperature of 22°C in our patients. Aortic valve resuspension was performed to repair acute aortic regurgitation in most of our patients with acute type A aortic dissection, with satisfactory results. However, composite graft replacement is indicated in patients with acute dissection associated with annuloaortic ectasia or Marfan's syndrome. Although the operative risk of the simultaneous composite graft replacement with total arch replacement was expected to be extremely high, we observed no operative or late deaths in the 5 patients we treated in this manner using recently refined surgical adjuncts and techniques. Although we used the original Bentall operation together with graft inclusion technique in the early period, we have observed the late complication of false aneurysm at the site of coronary anastomosis after Bentall operation, and therefore we currently use Carrel's button technique. Our current surgical indications for concomitant arch replacement in acute type A aortic dissection are as follows: aortic arch dissection, DeBakey type retrograde IIIb aortic dissection, rupture or massive false lumen of the aortic arch (or both), compromise of arch vessels, and Marfari's syndrome in a young patient without serious complications. In our series, the overall early mortality rate was 23.3%, which is not significantly different from that recently
KAZUI ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
1467
reported by other authors for patients with concomitant total arch replacement [6-8, 10]. The early mortality rate was, however, more than 50% to 60% in our patients with complication of shock or renal/mesenteric ischemia. The reported operative mortality rate for replacement of the ascending aorta is 50% to 70% in patients with acute, type A aortic dissection complicated by renal/mesenteric ischemia [3, 20]. Thus, it is clear that the preoperative critical condition of patients greatly influences the outcome of the operation, regardless of whether arch repair is performed. Consequently, relatively conservative surgical management, such as ascending aortic replacement alone or partial arch replacement, is indicated for patients with these severe dissection-related complications. The early mortality rate was 8.7%, and the 4-year survival rate 87%, in our 23 low-risk patients who had neither of these two risk factors. These rates are quite similar to the less than 10% early mortality rate reported by other authors for patients who underwent ascending aorta repair alone or partial arch replacement [3, 11]. Thus, it is suggested that, with refined modern technology, concomitant total arch replacement does not significantly increase the operative risk of patients with acute type A aortic dissection without serious dissection-related complications, or the presence of diabetes, coronary artery disease, and poor functional class as demonstrated by Crawford and associates [11]. Analysis of the operative results by site of primary intimal tear revealed that the early mortality rate was 43% in the 7 patients with intimal tear located at the ascending aorta. This high mortality rate was due to the presence of high risk factors in some of these patients. On the other hand, the operative mortality rate was 13.3% in the 15 patients with aortic arch dissection, which compares favorably with the rate in cases reported in the literature [9]. It has been reported that the distal false lumen remains patent postoperatively in most patients who have undergone ascending aorta repair for acute aortic dissection [21-24], whereas the event-free rate, including reoperation, for distal aortic lesion is only 70% at 6-year postoperatively, and even lower in young patients [11]. Moreover, Crawford and associates [25] reported that previous operation involving the ascending aorta or the aortic arch was a significant risk factor in patients who required aortic arch repair. These findings indicate that, even in patients with acute type A aortic dissection with intimal tear located at the ascending aorta or in young patients without risk factors, the ascending aorta and the total aortic arch should be replaced at the same time in the same surgical field. Repair of remaining lesions distal to the aortic arch, particularly in the thoracoabdominal aorta, may be performed if necessary at the second stage, through a left thoracotomy, in the late postoperative period. We may, therefore, reasonably conclude that simultaneous total arch replacement may be justified in selected patients with acute type A aortic dissection.
References 1. DeSanctis RW, Doroghazi RM, Austen WG, Buckley MJ.
Aortic dissection. New Engl J Med 1987;317:1060-7.
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2. Roberts CS, Roberts We. Aortic dissection with the entrance tear in transverse aorta: analysis of 12 autopsy patients. Ann Thorac Surg 1990;50:762-6. 3. Miller DC, Mitchell RS, Oyer PE, Stinson EB, Jamieson SW, Shumway NE. Independent determinants of operative mortality for patients with aortic dissections. Circulation 1984;70 (Suppl 1):153-64. 4. Haverich A, Miller DC, Scott WC, et al. Acute and chronic aortic dissection: determinants of long-term outcome for operative survivors. Circulation 1985;72 (Suppl II):22-34. 5. Graham JM, Stinnett DM. Operative management of acute aortic arch dissection using profound hypothermia and circulatory arrest. Ann Thorac Surg 1987;44:192-8. 6. Bachet I, Teodori G, Goudot B, et al. Replacement of the transverse aortic arch during emergency operation for type A acute aortic dissection. Report of 26 cases. J Thorac Cardiovasc Surg 1988;96:876-86. 7. Massimo CG, Presenti LF, Marranci P, et al. Extended and total aortic resection in the surgical treatment of acute type A aortic dissection: experience with 54 patients. Ann Thorac Surg 1988;46:420-4. 8. Lansman SL, Raissi S, Ergin MA, Griepp RB. Urgent operation for acute transverse aortic arch dissection. J Thorac Cardiovasc Surg 1989;97:334-41. 9. Yun KL, Glower DD, Miller DC, et al. Aortic dissection resulting from tear of transverse arch: is concomitant arch repair warranted? J Thorac Cardiovasc Surg 1991;102:355-70. 10. Heinemann M, Laas I, Iurmann M, Karck M, Borst HG. Surgery extended into the aortic arch in acute type A dissection. Indications, techniques, and results. Circulation 1991;87 (Suppl 3):25-30. 11. Crawford ES, Kirklin JW, Naftel DC, Svensson LG, Coselli JS, Safi HJ. Surgery for acute dissection of ascending aorta. Should the arch be included? J Thorac Cardiovasc Surg 1992;104:46-59. 12. Kazui T, Kimura N, Yamada 0, Komatsu S. Surgical outcome of aortic arch aneurysms using selective cerebral perfusion. Ann Thorac Surg 1994;57:904-11. 13. Kazui T, Inoue N, Yamada 0, Komatsu S. Selective cerebral perfusion during operation for aneurysms of the aortic arch: a reassessment. Ann Thorac Surg 1992;53:109-14. 14. Livesay JJ, Cooley DA, Duncan JM, Ott DA, Walker WE, Reul
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15. 16. 17.
18.
19.
20. 21.
22. 23. 24.
25.
GJ. Open aortic anastomosis: improved results in the treatment of aneurysms of the aortic arch. Circulation 1982;66 (Suppl 1):122-7. Galloway AC, Colvin SB, LaMendola CL, et al. Ten-year operative experience with 165 aneurysms of the ascending aorta and aortic arch. Circulation 1989;80 (Suppl 1):249-56. Kazui T, Inoue N, Komatsu S. Surgical treatment of aneurysms of the transverse aortic arch. J Cardiovasc Surg 1989;30:402-6. Treasure T, Naftel DC, Conger KA, Garcia JH, Kirklin JW, Blackstone EH. The effect of hypothermic circulatory arrest time on cerebral function, morphology, and biochemistry. J Thorac Cardiovasc Surg 1983;86:761-70. Fessatidis IT, Thomas VL, Shore DF, Sedgwick ME, Hunt RH, Weller RO. Brain damage after profoundly hypothermic circulatory arrest: correlations between neurophysiologic and neuropathologic findings. An experimental study in vertebrates. J Thorac Cardiovasc Surg 1993;106:32-41. Svensson LG, Crawford ES, Hess KR, et al. Deep hypothermia with circulatory arrest. Determinant of stroke and early mortality in 656 patients. J Thorac Cardiovasc Surg 1993;106: 19-31. Farm JI, Sarris GE, Mitchell RS, et al. Treatment of patients with aortic dissection presenting with peripheral vascular complications. Ann Surg 1990;212:705-13. Thomas CS Jr, Alford WC Jr, Burrus GR, Frist RA, Stoney WS. The effectiveness of surgical treatment of acute aortic dissection. Ann Thorac Surg 1978;26:42-9. Guthaner DF, Miller DC, Silverman JF, Stinson EB, Wexler L. Fate of the false lumen following surgical repair of aortic dissections: an angiographic study. Radiology 1979;133:1-8. Turley K, Ullyot DI, Godwin JD, et al. Repair of dissection of the thoracic aorta. Evaluation of false lumen utilizing computed tomography. J Thorac Cardiovasc Surg 1981;81:61-8. Cachera JP, Vouhe PR, Loisance DY, et al. Surgical management of acute dissections involving the ascending aorta. Early and late results in 38 patients. J Thorac Cardiovasc Surg 1981;82:576-84. Crawford ES, Svensson LG, Coselli JS, Safi HI, Hess KR. Surgical treatment of aneurysm and/or dissection of the ascending aorta, transverse aortic arch, and ascending aorta and transverse aortic arch. Factors influencing survival in 717 patients. J Thorac Cardiovasc Surg 1989;98:659-74.
Treatment of acute type A aortic dissection with emergency total aortic arch graft replacement remains controversial. Between December 1988 and July 1993, 30 patients with this fatal disease underwent graft replacement of both the ascending aorta and total aortic arch on an emergency basis. All operations were performed with the aid of extracorporeal circulation, blood cardioplegia, selective cerebral perfusion, and open distal anastomosis. The overall early mortality rate was 23.3% (7 patients), but that in patients with complications with shock and
renal/mesenteric ischemia was 57% and 66.7%, respectively. On the other hand, the mortality rate in the 23 patients (77%) in whom neither of these two risk factors was present was low (8.7%). The overall 4-year survival rate was 66.5% ± 8.7%, and that for patients without these two risk factors was 87.0% ± 7.0%. The present data suggest that simultaneous total arch replacement may be justified in selected patients with acute type A aortic dissection. (Ann Thorae Surg 1994;58:1462-8)
I
Material and Methods
t generally is accepted that patients with acute type A aortic dissection require emergency surgical intervention. Ascending aorta repair alone is the procedure of choice in most patients in whom the primary intimal tear is located in the ascending aorta. However, aortic arch dissection in which the intimal tear is located at the aortic arch is present in 10% to 20% of patients, and there is very little agreement as to the appropriate clinical strategy to be used in these cases. Although medical management has been advocated [1], emergency operation is necessary to save the life of patients during the acute stage because of the unfavorable medical outcome [2]. During emergency operation, ascending aorta replacement without resection of the arch tear has been performed in many centers to prevent the fatal cardiac tamponade [3,4]. However, with recent advances in various cerebral protection methods during aortic arch repair, aggressive aortic arch repair is increasingly performed [5-11]. The operative technique used in aortic arch repair varies with the institution and ranges from limited partial arch replacement to extended total arch replacement. For the last 7 years, we have used selective cerebral perfusion (SCP) for prevention of cerebral ischemia in the treatment of more than 100 patients with aortic arch aneurysm, with satisfactory results [12]. We describe herein our experience with simultaneous total arch replacement for acute type A aortic dissection, discuss the indications for this surgical procedure, and describe the operative technique using SCP and the outcome. Accepted for publication May 5,1994. Address reprint requests to Dr Kazui, Second Department of Surgery, Sapporo Medical University School of Medicine, South 1, West 17,Chuo-ku, Sapporo 060, Japan.
© 1994 by The Society of Thoracic Surgeons
Patient Profile The subjects were 30 consecutive patients who underwent graft replacement of the ascending aorta and total aortic arch for acute type A aortic dissection during the period between December 1988 and July 1993. Fifteen patients who underwent limited partial arch replacement during the same period are excluded from this study. Subjects ranged in age from 32 to 71 years, with a mean age (::!:: standard deviation) of 55.6 ::!:: 10.1 years. There were 20 men and 10 women. The preoperative complications included shock state requiring cardiopulmonary resuscitation in 7 patients (23%), cardiac tamponade in 12 (40%), rupture of the left pleural cavity in 1 (3%), aortic regurgitation in 17 (56%) including 5 with annuloaortic ectasia, myocardial ischemia in 2 (6%), transient cerebral ischemia in 507%), paraplegia in 1 (3%), renal/mesenteric ischemia in 6 (20%), leg ischemia in 7 (23%), and ischemia of two or more organs in 5 07%) (including transient cerebral ischemia and renal/mesenteric ischemia in 1 (3%), renal/ mesenteric ischemia and leg ischemia in 3 00%), and renal/mesenteric ischemia and leg ischemia and paraplegia in 1 (3%). Classic Marfan's syndrome was present in 3 patients. Fourteen (47%) of these 30 patients underwent preoperative aortography to confirm the diagnosis, and the remaining patients had undergone either computed tomography performed at another hospital or echocardiography, including transesophageal color Doppler technique after tracheal intubation in the operating room because of their critical condition. Assessment of both the preoperative diagnostic procedures and intraoperative findings indicated that a primary intimal tear was located at the ascending aorta in 7 patients, from the ascending aorta to the aortic arch in 6, at the aortic arch in 9, and at the 0003-4975/94/$7.00
Ann Thorae Surg 1994;58:1462-8
KAZUI ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
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proximal descending aorta in 5. In the remaining 3 patients, no intimal tear was found at the ascending aorta, aortic arch or proximal portion of the descending aorta during the operation. All operations were performed on an emergency basis during the acute stage within 2 weeks after the onset of symptoms. The average interval between onset and operation was 2.9 ± 2.7 days.
Operative Techniques In all patients, a median sternotomy and left supraclavicular incision were made to expose the heart, ascending aorta, aortic arch, and arch vessels. After systemic heparinization, extracorporeal circulation was instituted with the arterial return cannula placed in a femoral artery and a single two-stage cannula for venous drainage in the right atrium. The left side of the heart was vented through the right superior pulmonary vein. The ascending aorta was cross-clamped under electrical fibrillation; when the patient's temperature reached 32°C, the aorta was opened longitudinally and blood cardioplegia was infused directly into both coronary ostia. During cooling with extracorporeal circulation, aortic valve resuspension was performed in 12 patients with acute aortic regurgitation, and composite graft replacement with coronary reimplantation was performed in 5 patients with annuloaortic ectasia. In one of the latter patients, classic Bentall operation was performed as the operative technique for coronary reimplantation, while the 4 patients treated later in the period underwent Carrel's button technique. In the latter technique, the buttons of aorta from which the coronary arteries arose were excised, reinforced with a ring-shaped Teflon felt on the outside of the aorta and sewn to the side hole of the graft using a running 4-0 polypropylene suture. In 2 patients in whom the severe dissection involving the right coronary ostium was present, vein bypass grafting to the distal right coronary artery after ligation of the coronary ostium was performed. In another patient with significant stenosis of the left anterior descending artery, vein bypass grafting to this coronary artery was performed. After the aortic valve repair and distal graft anastomosis of the coronary artery bypass grafting, the ascending aorta and the aortic arch were reconstructed. Selective cerebral perfusion was used in all patients to prevent cerebral ischemia during the aortic arch repair. The SCP procedure used has been reported in detail elsewhere [13]. The two operative techniques used for aortic arch reconstruction are illustrated in Figure 1 and described below. "EN-BLOC" REPAIR TECHNIQUE. This operative technique was used in the first 4 patients treated in the study period. The aorta was opened, and the proximal false lumen was obliterated with two Teflon strips. When the rectal temperature dropped to 22°C, SCP cannulas were inserted into the innominate and left common carotid arteries. The route of cannula insertion depended on the degree of arch vessel involvement. After systemic circulation was arrested and the aorta was opened, the cannulas were inserted directly into the distal portion of the vessels when the vessels were
Fig 1. Surgical techniques used in graft replacement of both the ascending aorta and the total aorticarch, performed in 30 patients.
not involved with the dissection, and internally through the aortic lumen when the vessels were severely involved. Blood then was perfused into both arteries at the rate of 10 mL· kg-I. min- 1 for both vessels, using a single roller pump separated from the systemic circulation. With the distal end of the aortic arch left open, distal graft anastomosis and aortic arch reconstruction were performed. During this open aortic anastomosis, blood perfusion to the lower half of the body from the femoral artery was arrested or reduced to approximately 500 mL/min. Blood was aspirated from the operative field and returned to the cardiopulmonary bypass circuit. The distal false lumen at the site of the proximal descending aorta just below the junction with the left subclavian artery was obliterated in a similar fashion. A soft woven Dacron graft of low porosity was then anastomosed to the descending aorta using a continuous 3-0 polypropylene suture. The orifices of the arch vessels at the cuff remaining after obliteration of the false lumen in the aortic arch were anastomosed in an end-to-side fashion to the side hole on the graft. Following reconstruction of the arch vessels, the graft was cross-clamped proximally, the SCP cannulas were removed, and cerebral circulation was started and rewarmed by extracorporeal circulation. The proximal end of the graft was then anastomosed to the proximal stump of the ascending aorta using a continuous 3-0 polypropylene suture. Immediately before completion of the anastomosis, air was evacuated from the graft, and coronary circulation was started. Finally, the graft was wrapped with the aneurysmal wall. This operative procedure with "nonwrapping technique" was used in the last 26
SEPARATED GRAFT TECHNIQUE.
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KAZUI ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
patients treated in the study period. The ascending aorta just above the aortic commissures was completely transected, and the proximal false lumen was obliterated with two Teflon strips. When the patient's temperature cooled to 22°C during extracorporeal circulation, the aorta was declamped and the systemic circulation from the femoral artery was arrested. Selective cerebral perfusion cannulas were inserted directly into the innominate and left common carotid arteries through the aortic lumen internally, and SCP was started. Open aortic anastomosis was then performed. The descending aorta just distal to the origin of the left subclavian artery was transected circumferentially, and the distal false lumen was obliterated in a similar fashion. In patients with DeBakey type retrograde IIIb dissection, the descending aorta distal to the site of intimal tear was transected. A graft provided with three limbs was then anastomosed to the distal stump of the descending aorta using a continuous 3-0 polypropylene suture. After completion of the distal graft anastomosis, the proximal graft was cross-clamped, and recirculation and rewarming with extracorporeal circulation were started at the graft of the left subclavian artery or the fourth graft attached to the main graft, rather than at the femoral cannula. During the rewarming period, the proximal graft was anastomosed to the proximal stump of the ascending aorta using a continuous 3-0 polypropylene suture. Before completion of the proximal anastomosis, the air was evacuated from the graft and coronary circulation was started. The three limbs of the graft were then anastomosed in succession to, respectively, the innominate, left common carotid, and left subclavian arteries using a running 4-0 polypropylene suture. Each SCP cannula was removed immediately before completion of the respective arch vessel anastomosis. In most patients, the heart was defibrillated with direct-current countershock during the arch vessel reconstruction. In no patient was the graft wrapped with aneurysmal wall to obtain hemostasis.
Statistical Methods The continuous data in this article are expressed as the mean ± standard deviation. Differences between categoric parameters were assessed by >1 test or Student's t test; a p value of less than 0.05 was considered to be statistically significant. The actuarial survival rates were calculated by the Kaplan-Meier method (with variability expressed as standard error of the estimate) and compared using the log rank test.
Results Early Mortality The overall 30-day mortality rate was 23.3% (7 of the 30 patients). One patient died in the operating room. Table 1 shows the relationship of various preoperative and perioperative variables to the early postoperative mortality rate. This rate was 57.1% in patients with the preoperative complication of shock and 66.7% those with renal/ mesenteric ischemia; this rate was significantly higher than that in patients without the respective factor (both p <
Table 1. Preoperative and Perioperative Variables and Early Mortality Rate Earll; Morta ity Variable Total patients Sex Male Female Age (y) 24-35 36-45 46-55 56-65 66-75
No. of Patients
No. of Patients
%
30
7
23.3
20 10
4 3
20 30
1 3 8 12 6
0 0 2 4 1
0 0 25 33.3 16.7
NS NS
Interval between onset and operation (h) 0-24 25-48 49-72 73-108 109-336
Site of intimal tear AscAo Aso AD-Arch Arch Des Ao Unknown Shock (+) (-)
NS 10 8 6 4 2
2 1 2 2 0
20.0 12.5 33.3 50.0 0
7 6 9 5 3
3 2 0 1 1
42.8 33.3 0 20.0 33.3
7 23
4 3
57.1 13.0
12 18
4 3
33.3 16.7
1 29
0 7
0 29.1
17 13
3 4
17.6 30.0
2 28
1 6
50.0 21.4
5 25
0 7
0 28
1 29
1 6
100 20.7
6 24
4 3
66.7 12.5
7 23
3 4
42.9 17.4
NS
<0.05
Cardiac tamponade (+) (-)
NS
Pleural rupture (+) (-)
NS
AR (+) (-)
NS
Myocardial ischemia (+) (-)
NS
Cerebral ischemia (+) (-)
NS
Paraplegia (+) (-)
NS
Renal! mesenteric ischemia (+) (-)
Leg ischemia (+) (-)
<0.05
NS NS
Two or more organs ischemia (+) (-)
p Value
5 25
3 4
60 16.0
Continued on next page
KAZU1 ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
Ann Thorac Surg 1994;58:1462-8
Causes of Early Mortality
Table 1. Continued Early Mortality Variable
No. of Patients
No. of Patients
%
7 23
5 2
71.4 8.7
12 18
3 4
25.0 22.2
5 25
0 7
0 28.0
3 27
1 6
33.3 22.2
NS
A/V resuspension (+) (-)
NS
Composite graft (+) (-)
NS
CABG (+) (-)
Arch reconstruction En bloc Separated graft Graft replacement Inclusion technique Nonwrapping technique
p Value <0.01
Shock + renal/mesenteric ischemia (+) (-)
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NS 4 26
0 7
0 26.9
4 26
0 17
0 26.9
NS
AR = aortic regurgitation; Asc Ao = ascending aorta; A/V = aortic Des Ao = descendvalve; CABG = coronary artery bypass grafting; ing aorta; NS = not significant.
The patient who died in the operating room had distal fenestration at the site of descending aortic anastomosis; the cause of death was rupture of the descending aorta. In 1 patient each, the cause of early death was hemorrhage at the anastomosed site of the aorta secondary to postoperative mediastinitis on the fifteenth postoperative day, multiple organ failure on the eighteenth postoperative day in a patient with preoperative paraplegia, renal/mesenteric ischemia and leg ischemia, abdominal aortic rupture into the retroperitoneal cavity on the third postoperative day, and low cardiac output syndrome in a patient requiring intraaortic balloon pump and a left ventricular assist device on the thirteenth postoperative day. The remaining 2 patients died of respiratory failure on the fourteenth and twenty-fourth postoperative days, respectively.
Extracorporeal Circulation Data The data concerning extracorporeal circulation in the surviving patients in en bloc repair and separated graft groups are compared in Table 2. Total pump time, cardiac ischemia time, SCP time, and open distal anastomosis time in the en bloc repair group were significantly longer than those in the separated graft group.
Late Survival
0.05). Moreover, in the 7 patients (23%) with both of these factors, the early mortality rate was 71.4% (high-risk group). On the other hand, in the 23 patients (77%) in whom both of these factors were absent, the early mortality rate was 8.7% (low-risk group), which was significantly lower than that in the high-risk group (p < 0.01). The early mortality rate was not correlated with patient age, sex, cardiac tamponade, pleural rupture, aortic regurgitation, myocardial ischemia, cerebral ischemia, paraplegia, ischemia of two or more organs, interval between onset and operation, site of intimal tear, aortic valve resuspension, composite graft replacement, coronary artery bypass grafting, or operative technique for arch vessel reconstruction or graft replacement.
The 23 patients who survived the early postoperative period were followed up postoperatively for an average of 1.4 years (range, 4 months to 4 years and 9 months). Figure 2 shows the actuarial survival rate calculated by the Kaplan-Meier method. The overall survival curve reached a plateau 1 year after the operation. The 4-year survival rate for all patients, including those with early mortality, was 66.5% ± 8.7%. All 7 patients in the high-risk group with both preoperative shock and renal/mesenteric ischemia died within 1 year after the operation. The 4-year survival rate for the 23 patients in the low-risk group was 87.0% ± 7.0%, which was significantly higher than that in the high-risk group (p < 0.001). Three patients died during the late postoperative period. The cause of late death in these patients was multiple organ failure in the fourth postoperative month, hepatic failure in the sixth postoperative month, and pneumonitis
Early Morbidity
Table 2. Extracorporeal Circulation Data
All patients who survived the operation (n = 29) regained consciousness postoperatively without any distinct sign of stroke. Postoperative complications included hemorrhage requiring rethoracotomy in 1 patient, pulmonary failure requiring the aid of a respirator for more than 5 days after operation in 19 patients, renal failure indicated by blood urea nitrogen level of more than 70 mg/dL or serum creatinine level of more than 3.0 mg/dL in 7 patients, hepatic failure with total bilirubin level of more than 3.0 mg/dL or glutamic-pyruvic transaminase level of more than 100 units in 3 patients, low cardiac output syndrome requiring intraaortic balloon pump and left ventricular assist device in 1 patient, and multiple organ failure in 5 patients.
Arch Reconstruction
Variable Total pump time (min) Cardiac ischemia time (min) SCP time (min) Open distal anastomosis time (min)
En bloc Repair (n = 4)
Separated graft" (n = 25)
Value
300 :': 65 217 :': 51
215 :': 65 137:': 41
<0.05 <0.01
125 :': 25 100:': 10
96:': 20 51:': 16
<0.05 <0.01
p
a Data for 1 patient who died in the operating room are excluded from this analysis.
SCP = selective cerebral perfusion.
1466
KAZUl ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
Ann Thorae Surg 1994;58:1462-8
100% , . . , . . . . - - - - - - - - - - - - - - - - - - - - - - ,
h"c
1\ L I
(21)
(21)
(23)
(23)
,
870+70"1.
'--(1·g)--------(i5j-------i9i---------(6i------·-=(~)·,. (20)
I I
0~
~
~
66.5+8.7%
~
I
1 L
- - Overall (n.30) - - - - - _. Low risk group{n=23) - - - High risk group (n.7) P
28.8±17.1'10
(2)----'
I
*
(2) L _ _ ~
I
o
1M
3M
8M
lY
2Y
3Y
4Y
Survival Time
Fig 2. Actuarial survival curvesfor patients who underwent graft replacement of both the ascending aorta and total aortic arch for acute type A aortic dissection by risk group. (Numbers in parentheses indicate number of patients at risk at each interval.)
in the fifth postoperative month. Two former causes of late death were apparently related to preoperative critical condition, including renal/mesenteric ischemia. The other 20 patients are presently leading normal lives. Postoperative aortography and computed tomographic scans performed on 20 patients to evaluate the patency of residual false lumen in the distal descending and abdominal aorta revealed patency of the distal false lumen in the distal aorta in 11 (55%) of these patients. One patient with patent false lumen underwent total graft replacement of the thoracoabdominal aorta for aneurysmal dilation of the false channel in the distal aorta 1 year 5 months postoperatively. This patient was discharged in good condition without paraplegia. Comment There is no disagreement that emergency operation should be performed for acute type A aortic dissection to prevent fatal cardiac tamponade during the acute stage. Because the primary intimal tear is usually located at the ascending aorta in the majority of patients with acute type A aortic dissection, resection of the intimal tear and graft replacement of the ascending aorta are routinely performed. However, there is controversy regarding the operative procedure which should be used in aortic arch dissection in which the primary intimal tear is located at or extends into the aortic arch. The theoretical ideal in such cases would be resection of the aortic arch tear and simultaneous aortic arch repair with graft replacement of the ascending aorta. However, the Stanford group has been reluctant to perform the concomitant aortic arch repair because the operative mortality rate is as high as 50% to 75% in these patients, and because there is no significant difference between groups with and without resection of the intimal tear in the aortic arch in operative or late mortality rate [1, 2]. However, the reoperation rate within 1 year after the operation is as high as 30% in patients without resection of the intimal tear [2]. On the other hand, with the recent improvement of adjunct technique for the prevention of
cerebral ischemia during aortic arch repair, aortic arch reconstruction is increasingly more aggressive, even in emergency operation for acute type A aortic dissection [5-11]. The operative technique used for aortic arch reconstruction ranges from partial to total arch replacement. In most reported operations, the open distal and hemiarch inclusion technique was performed with the aid of hypothermic circulatory arrest [14, 15]. In the patients we treated in the early period, we used this technique for aortic arch dissection in which the intimal tear was located adjacent to the orifice of the innominate artery. The 4-year survival rate for the partial arch group was 73.3% :t 11.4%, which was not statistically significant from 66.5% :t 8.7% for the total arch group. However, since 2 of our patients who underwent partial arch replacement required reoperation for late aneurysmal formation of a residual false lumen in the aortic arch, we now more often perform the more extended total arch replacement. As the technique for graft replacement we used the graft inclusion technique in the early period, but more recently we have used the nonwrapping technique because of the advantage of more accurate graft anastomosis associated with lower risk of hemorrhage in the early postoperative period and of false aneurysm at the site of graft anastomosis in the late period [7]. In addition, as the operative technique for total aortic arch replacement, we now use the separated graft technique instead of en bloc repair technique, not because it allows more precise reconstruction of the arch vessels in patients with the complication of compromise of arch vessels, but also because the total bypass and operation times are reduced. Specifically, the myocardial ischemia time, open distal anastomosis time, and total bypass time in the separated graft group in our study were significantly shorter than those in the en bloc repair group (Table 2). In the former group, after the distal graft anastomosis is completed, recirculation and rewarming with extracorporeal circulation are started through the side graft attached to the main graft, coronary circulation is started following the completion of the proximal graft anastomosis, and the arch vessels are then constructed while the heart is beating. We previously reported that both hypothermic circulatory arrest and SCP are useful methods in the prevention of cerebral ischemia during surgical reconstruction of the aortic arch [16]. Hypothermic circulatory arrest requires no special equipment or cannulation of arch vessels, and the procedure itself is simple, but the time available for cerebral circulatory arrest is restricted; the safe limit is 40 to 60 minutes, even with profound hypothermia [17-19]. Moreover, there are complications of coagulopathy or pulmonary insufficiency related to profound hypothermia, as well as cerebral complication. The incidence of cerebral complication after aortic arch repair in acute aortic dissection is reported to be 7% to 35% [6,8, 14, 15]. On the other hand, SCP presents the advantage of less restricted cerebral protection, and it did not produce any serious postoperative cerebral complications in our patients, even after about 100 minutes of cerebral protection. Therefore, to ensure safety, we used SCP in all patients with acute aortic dissection requiring total arch replace-
Ann Thorac Surg 1994;58:1462-8
ment, because it is difficult to estimate how long before operation the circulation of the aortic arch should be interrupted. One disadvantage of SCP is that it involves a complicated manipulation process. We made an effort to simplify our SCP technique, such as using two-vessel perfusion with a single pump and monitoring the right radial pressure as a measure of perfusion pressure, with satisfactory results. Another disadvantage of SCP is that the arch vessels, which might be involved in the dissection, should be cannulated. In our experience, the cannulas could be inserted easily into the distal portion of the branches when the arch vessels were not involved with dissection, and safely inserted internally if the true lumen could be distinguished from the aortic lumen when the branches to be cannulated were extensively involved. No complications due to cannulation were observed in any of our patients. The SCP cannulas used in our surgical procedure are flexible silicone tubes and do not usually obscure the operative field. When hypothermic circulatory arrest is used, "open distal anastomosis", in which the distal graft anastomosis is performed while the distal aortic arch is left open, is performed [5,8, 14]. This open distal anastomosis presents several advantages, including protection of the fragile aortic wall from damage by the aortic cross-clamp, easy obliteration of the distal false lumen, reinforcement of the aortic wall in a bloodless operative field, and accurate anastomosis of the graft to the distal aorta. For these reasons, we used open distal anastomosis combined with SCP in acute aortic dissection when reconstruction of the aortic arch was required. There was no postoperative paraplegia due to spinal cord ischemia during over 70 minutes of circulatory arrest at the temperature of 22°C in our patients. Aortic valve resuspension was performed to repair acute aortic regurgitation in most of our patients with acute type A aortic dissection, with satisfactory results. However, composite graft replacement is indicated in patients with acute dissection associated with annuloaortic ectasia or Marfan's syndrome. Although the operative risk of the simultaneous composite graft replacement with total arch replacement was expected to be extremely high, we observed no operative or late deaths in the 5 patients we treated in this manner using recently refined surgical adjuncts and techniques. Although we used the original Bentall operation together with graft inclusion technique in the early period, we have observed the late complication of false aneurysm at the site of coronary anastomosis after Bentall operation, and therefore we currently use Carrel's button technique. Our current surgical indications for concomitant arch replacement in acute type A aortic dissection are as follows: aortic arch dissection, DeBakey type retrograde IIIb aortic dissection, rupture or massive false lumen of the aortic arch (or both), compromise of arch vessels, and Marfari's syndrome in a young patient without serious complications. In our series, the overall early mortality rate was 23.3%, which is not significantly different from that recently
KAZUI ET AL ARCH REPLACEMENT IN AORTIC DISSECTION
1467
reported by other authors for patients with concomitant total arch replacement [6-8, 10]. The early mortality rate was, however, more than 50% to 60% in our patients with complication of shock or renal/mesenteric ischemia. The reported operative mortality rate for replacement of the ascending aorta is 50% to 70% in patients with acute, type A aortic dissection complicated by renal/mesenteric ischemia [3, 20]. Thus, it is clear that the preoperative critical condition of patients greatly influences the outcome of the operation, regardless of whether arch repair is performed. Consequently, relatively conservative surgical management, such as ascending aortic replacement alone or partial arch replacement, is indicated for patients with these severe dissection-related complications. The early mortality rate was 8.7%, and the 4-year survival rate 87%, in our 23 low-risk patients who had neither of these two risk factors. These rates are quite similar to the less than 10% early mortality rate reported by other authors for patients who underwent ascending aorta repair alone or partial arch replacement [3, 11]. Thus, it is suggested that, with refined modern technology, concomitant total arch replacement does not significantly increase the operative risk of patients with acute type A aortic dissection without serious dissection-related complications, or the presence of diabetes, coronary artery disease, and poor functional class as demonstrated by Crawford and associates [11]. Analysis of the operative results by site of primary intimal tear revealed that the early mortality rate was 43% in the 7 patients with intimal tear located at the ascending aorta. This high mortality rate was due to the presence of high risk factors in some of these patients. On the other hand, the operative mortality rate was 13.3% in the 15 patients with aortic arch dissection, which compares favorably with the rate in cases reported in the literature [9]. It has been reported that the distal false lumen remains patent postoperatively in most patients who have undergone ascending aorta repair for acute aortic dissection [21-24], whereas the event-free rate, including reoperation, for distal aortic lesion is only 70% at 6-year postoperatively, and even lower in young patients [11]. Moreover, Crawford and associates [25] reported that previous operation involving the ascending aorta or the aortic arch was a significant risk factor in patients who required aortic arch repair. These findings indicate that, even in patients with acute type A aortic dissection with intimal tear located at the ascending aorta or in young patients without risk factors, the ascending aorta and the total aortic arch should be replaced at the same time in the same surgical field. Repair of remaining lesions distal to the aortic arch, particularly in the thoracoabdominal aorta, may be performed if necessary at the second stage, through a left thoracotomy, in the late postoperative period. We may, therefore, reasonably conclude that simultaneous total arch replacement may be justified in selected patients with acute type A aortic dissection.
References 1. DeSanctis RW, Doroghazi RM, Austen WG, Buckley MJ.
Aortic dissection. New Engl J Med 1987;317:1060-7.
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2. Roberts CS, Roberts We. Aortic dissection with the entrance tear in transverse aorta: analysis of 12 autopsy patients. Ann Thorac Surg 1990;50:762-6. 3. Miller DC, Mitchell RS, Oyer PE, Stinson EB, Jamieson SW, Shumway NE. Independent determinants of operative mortality for patients with aortic dissections. Circulation 1984;70 (Suppl 1):153-64. 4. Haverich A, Miller DC, Scott WC, et al. Acute and chronic aortic dissection: determinants of long-term outcome for operative survivors. Circulation 1985;72 (Suppl II):22-34. 5. Graham JM, Stinnett DM. Operative management of acute aortic arch dissection using profound hypothermia and circulatory arrest. Ann Thorac Surg 1987;44:192-8. 6. Bachet I, Teodori G, Goudot B, et al. Replacement of the transverse aortic arch during emergency operation for type A acute aortic dissection. Report of 26 cases. J Thorac Cardiovasc Surg 1988;96:876-86. 7. Massimo CG, Presenti LF, Marranci P, et al. Extended and total aortic resection in the surgical treatment of acute type A aortic dissection: experience with 54 patients. Ann Thorac Surg 1988;46:420-4. 8. Lansman SL, Raissi S, Ergin MA, Griepp RB. Urgent operation for acute transverse aortic arch dissection. J Thorac Cardiovasc Surg 1989;97:334-41. 9. Yun KL, Glower DD, Miller DC, et al. Aortic dissection resulting from tear of transverse arch: is concomitant arch repair warranted? J Thorac Cardiovasc Surg 1991;102:355-70. 10. Heinemann M, Laas I, Iurmann M, Karck M, Borst HG. Surgery extended into the aortic arch in acute type A dissection. Indications, techniques, and results. Circulation 1991;87 (Suppl 3):25-30. 11. Crawford ES, Kirklin JW, Naftel DC, Svensson LG, Coselli JS, Safi HJ. Surgery for acute dissection of ascending aorta. Should the arch be included? J Thorac Cardiovasc Surg 1992;104:46-59. 12. Kazui T, Kimura N, Yamada 0, Komatsu S. Surgical outcome of aortic arch aneurysms using selective cerebral perfusion. Ann Thorac Surg 1994;57:904-11. 13. Kazui T, Inoue N, Yamada 0, Komatsu S. Selective cerebral perfusion during operation for aneurysms of the aortic arch: a reassessment. Ann Thorac Surg 1992;53:109-14. 14. Livesay JJ, Cooley DA, Duncan JM, Ott DA, Walker WE, Reul
Ann Thorac Surg 1994;58:1462-8
15. 16. 17.
18.
19.
20. 21.
22. 23. 24.
25.
GJ. Open aortic anastomosis: improved results in the treatment of aneurysms of the aortic arch. Circulation 1982;66 (Suppl 1):122-7. Galloway AC, Colvin SB, LaMendola CL, et al. Ten-year operative experience with 165 aneurysms of the ascending aorta and aortic arch. Circulation 1989;80 (Suppl 1):249-56. Kazui T, Inoue N, Komatsu S. Surgical treatment of aneurysms of the transverse aortic arch. J Cardiovasc Surg 1989;30:402-6. Treasure T, Naftel DC, Conger KA, Garcia JH, Kirklin JW, Blackstone EH. The effect of hypothermic circulatory arrest time on cerebral function, morphology, and biochemistry. J Thorac Cardiovasc Surg 1983;86:761-70. Fessatidis IT, Thomas VL, Shore DF, Sedgwick ME, Hunt RH, Weller RO. Brain damage after profoundly hypothermic circulatory arrest: correlations between neurophysiologic and neuropathologic findings. An experimental study in vertebrates. J Thorac Cardiovasc Surg 1993;106:32-41. Svensson LG, Crawford ES, Hess KR, et al. Deep hypothermia with circulatory arrest. Determinant of stroke and early mortality in 656 patients. J Thorac Cardiovasc Surg 1993;106: 19-31. Farm JI, Sarris GE, Mitchell RS, et al. Treatment of patients with aortic dissection presenting with peripheral vascular complications. Ann Surg 1990;212:705-13. Thomas CS Jr, Alford WC Jr, Burrus GR, Frist RA, Stoney WS. The effectiveness of surgical treatment of acute aortic dissection. Ann Thorac Surg 1978;26:42-9. Guthaner DF, Miller DC, Silverman JF, Stinson EB, Wexler L. Fate of the false lumen following surgical repair of aortic dissections: an angiographic study. Radiology 1979;133:1-8. Turley K, Ullyot DI, Godwin JD, et al. Repair of dissection of the thoracic aorta. Evaluation of false lumen utilizing computed tomography. J Thorac Cardiovasc Surg 1981;81:61-8. Cachera JP, Vouhe PR, Loisance DY, et al. Surgical management of acute dissections involving the ascending aorta. Early and late results in 38 patients. J Thorac Cardiovasc Surg 1981;82:576-84. Crawford ES, Svensson LG, Coselli JS, Safi HI, Hess KR. Surgical treatment of aneurysm and/or dissection of the ascending aorta, transverse aortic arch, and ascending aorta and transverse aortic arch. Factors influencing survival in 717 patients. J Thorac Cardiovasc Surg 1989;98:659-74.