Interact CardioVasc Thorac Surg 2007;6:204-207. doi:10.1510/icvts.2006.132233
© 2007 European Association of Cardio-Thoracic Surgery
Institutional report - Vascular thoracic |
Patency of distal false lumen in acute dissection: extent of resection and prognosis
Genichi Sakaguchi*,
Tatsuhiko Komiya,
Nobushige Tamura,
Chieri Kimura,
Taira Kobayashi,
Hiromasa Nakamura,
Tomokuni Furukawa and
Akihito Matsushita
Department of Cardiovascular Surgery, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki City, Okayama, 710-8602, Japan
Received 1 March 2006;
received in revised form 20 October 2006;
accepted 16 November 2006
*Corresponding author. Tel.: +81-86-448-1111; fax: +81-86-421-3424.
E-mail address: gs8722{at}kchnet.or.jp (G. Sakaguchi).
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Abstract
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We assessed the hypotheses that extension of aortic replacement would reduce the patency of the false lumen of the descending aorta and that postoperative patency of the false lumen would result in poor prognosis. One hundred and twenty-four consecutive patients underwent surgical repair for acute type A acute dissection on an emergency basis. Among the 124 patients, 89 patients had De Bakey type I dissection. Among the patients with De Bakey type I dissection, the false lumen of the descending aorta was preoperatively patent in 52 patients. Distal extent of aortic replacement was ascending aorta in 16 patients, hemiarch in 15 patients, partial arch in seven patients, and total arch in 11 patients. Patency of the false lumen was not influenced by distal extent of the aortic replacement. In a one-year follow-up, the maximum diameter of the descending aorta with patent false lumen had increased significantly than that with closed false lumen. Survival rates were 96% at one year and 67% at five years in the patients with patent false lumen and no mortality in the patients with closed false lumen. Patency of the false lumen was not influenced by extension of aortic replacement and associated with poor prognosis.
Key Words: Acute aortic dissection; Prognosis
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1. Introduction
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The aim of an emergent operation for acute aortic dissection (AD) is to rescue the patients at risk of death by rupture of the ascending aorta. When the intimal tear is located in the ascending aorta, replacement of the ascending aorta has been widely accepted as a standard strategy [1]. However, as operative mortality for acute AD has been improving for the last decade with the advances in operative techniques including hypothermic circulatory arrest, retrograde cerebral perfusion, and selective cerebral perfusion which enable complete elimination of the primary tear and open distal anastomosis, extended total arch replacement has been advocated as an aggressive approach with good clinical outcomes instead of ascending and hemi-arch replacements [2]. Nevertheless, the late mortality and aortic complications have still remained high, particularly when the distal false lumen is patent [3–6]. This study was undertaken to assess the impact of the extent of the aortic replacement on the obliteration of the false lumen of the descending aorta and the prognosis of the patent false lumen in De Bakey I AD.
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2. Patients and methods
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2.1. Patients
Between April 1994 and March 2004, 124 patients underwent surgical repair for acute type A AD on an emergency basis. The diagnosis was made by both enhanced computed tomographic (CT) scan and echocardiography. Patency of the false lumen in the descending aorta was measured at the level of the left atrium. Among the 124 patients, 89 patients had De Bakey I dissection, 19 patients had De Bakey type II dissection and 16 patients had De Bakey type III retrograde dissection. Among the 89 patients with De Bakey type I dissection, 15 cases had the dissection which stopped in the transverse arch and no dissection in the descending aorta. Among the remaining 74 cases of De Bakey type I dissection, false lumen of the descending aorta was preoperatively patent in 52 patients. We retrospectively studied 49 patients among the 52 patients, excluding three hospital deaths. Mean follow-up period was 49.5±33.3 months.
2.2. Procedures
Operations were performed within 48 h after the onset of symptoms (10.3±8.9 h). Cardiopulmonary bypass (CPB) was established by using the femoral artery for the arterial return in 42 patients and the right axillary artery in seven patients. The interior of the aortic arch and the proximal descending aorta were examined during the circulatory arrest and the location of the primary entry was identified. Then, the extent of the aortic replacement was determined according to the location of the primary entry. Our surgical strategy for type A AD has been to eliminate the primary entry. Ascending aortic replacement was performed when the primary entry was located in the ascending aorta. Hemiarch or partial arch replacement was performed when the primary entry was located in the lesser curvature of the transverse arch. When hemiarch replacement was considered to be unfavorable because of a long suture line in the distal anastomosis, partial arch replacement (innominate artery reconstruction) was chosen. Total arch replacement was performed when the primary entry was located in the anterior wall of the transverse arch or with rupture of the transverse arch. The extent of distal resection was the ascending aorta in 16 patients, the hemiarch in 15 patients, the partial arch in seven patients, and the total arch in 11 patients. Distal anastomosis was performed by an open distal technique during deep hypothermic circulatory arrest (21.5±3.6 °C). Selective antegrade cerebral perfusion was used in 36 patients and retrograde cerebral perfusion in 14 cases for cerebral protection during the deep hypothermic circulatory arrest. The dissected layers at the anastomosis were reapproximated with gelatin resorcin formaldehyde (GRF) glue and the suture line was reinforced by a Teflon strip externally. After completion of the open distal anastomosis, the graft was clamped and antegrade systemic perfusion was started through a side branch of the graft. The arch vessels were independently reconstructed by using a tube graft with four limbs in cases with total arch replacement.
2.3. Informed consent
The Institutional Review Board of Kurashiki Central Hospital approved this study, and waived the individual consent because this study was retrospective.
2.4. Statistical analysis
The continuous data are expressed as the mean±S.E.M. Categorical variables were compared by means of  2 analysis. Continuous variables were compared by means of Student's t-test or one-way analysis of variance (ANOVA). Changes in the size of descending aorta were analyzed by means of two-way repeated measures ANOVA. The univariate analysis was followed by stepwise logistic regression to determine independent risk factors for patency of the false lumen. Survival analysis was performed with Kaplan–Meier analysis. Differences were considered significant at the level of P<0.05.
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3. Results
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In postoperative CT studies, the false lumen of the descending aorta was still patent in 32 patients (patent group) and totally thrombosed in 17 patients (thrombosed group). Patient characteristics are shown in Table 1. Preoperative maximum size of the descending aorta in the patent group was significantly larger than that in the thrombosed group. Fig. 1 shows changes in the maximum size of descending aorta. The patent false lumen was significantly larger than the closed false lumen after one year. Two-way repeated measures ANOVA showed high group and time effects within two years after the surgery. Operative techniques are shown in Table 2. Patency of the distal false lumen was not significantly different among four types of the operations (ascending replacement: 81%, hemiarch: 53%, partial arch: 57%, total arch: 64%, P=0.397). CPB and cerebral perfusion (selective antegrade or retrograde perfusion) times were significantly longer in the total arch replacement than those in the other replacements. Patency of the false lumen was not influenced by the site of the arterial return (femoral artery: 67%, axillary artery: 57%). Multivariate analysis revealed that statistically significant independent predictors of postoperative patent false lumen were preoperative hypertension which required aggressive use of an anti-hypertensive drug (odds ratio: 8.18, 95% CI: 1.36–49.11, P=0.022) and the preoperative size of the descending aorta at 35 mm (odds ratio: 22.91, 95% CI: 3.43–152.85, P=0.0012). Fig. 2 shows the actuarial survival curves and re-operation free curves according to the postoperative patency of the false lumen. During the follow-up after discharge, there were 6 late deaths in the patent group. Two patients died at the re-operation. Six patients in the patent group underwent late re-operations. One patient in the closed group underwent aortic root replacement for re-dissection in the aortic root.
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4. Discussion
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Acute type AD is a catastrophic event, which requires urgent surgical treatment to rescue the patients at risk of death by the rupture of the ascending aorta. The operative mortality rate has been decreasing over time with advances in surgical techniques and early diagnosis [1,7]. The in-hospital mortality of AD in our institution was 7.5% for the last decade. Our surgical strategies are to resect the primary entry and open distal anastomosis under deep hypothermic circulatory arrest. These strategies might contribute to these satisfactory early results [8]. On the other hand, there were six re-operations and the mortality of the re-operation was greatly increased (33%). Dilatation of the descending aorta due to patent false lumen resulted in late re-operation in four cases. Patent false lumen is responsible for progressive aortic dilatation and late mortality [4,6,9]. The present study showed progressive dilatation of the descending aorta with patent false lumen even after the primary entry was resected. The secondary tears and the leaks through the distal suture lines into the false lumen may account for the persistent patent false lumen after the complete resection of the primary entry [3]. The present study showed the preoperative size of the descending aorta at 35 mm as a strong independent predictor for the postoperative patent false lumen. The preoperative large size of the descending aorta (particularly large patent false lumen) would be related to the pulsatile antegrade flow through the primary tear, exiting via the secondary tears in the downstream aorta [3]. In such cases, even after the complete resection of the primary tear, the remaining secondary tears may still allow the pulsatile flow in the false lumen, resulting in its dilatation. The results indicate that the preoperative size of the patent false lumen can predict the poorer prognosis regarding the late dilatation of the distal aorta.
Even though operative mortality for acute AD has been improving with increased surgical experiences and advances in operative techniques, we believe it is still a surgical challenge if the resection is extended toward the total arch replacement, especially in high-risk patients. In our series, while CPB and cerebral perfusion time were significantly longer in the total arch replacement than in the other replacements, the patency of the false lumen in the descending aorta was not influenced by the extension of the replacement. It remains controversial whether aortic replacement should be extended beyond the transverse arch in De Bakey type I AD even when the primary tear is located in the ascending aorta or the proximal arch. Extension of the aortic replacement may not increase the surgical risk, because the risk depends not only on the complexity of the procedure, but also the preoperative complications including malperfusion, cardiac tamponade, and rupture [10,11]. Apaydin and colleagues reported that the location of the intimal tear and extent of the replacement did not have any impact on the early mortality [11]. In addition, extended total arch replacement has been advocated as an aggressive approach with good clinical outcomes instead of ascending and hemi-arch replacements [2,12,13]. On the other hand, Ehrlich and colleagues reported, analyzing a large consecutive series of patients with acute type A AD, that the site of the intimal tear did not influence outcome, but mortality rate was higher with more extensive resection [14]. The mortality of resection, including the descending aorta, was 43% and that of ascending aorta or hemiarch replacement was 14%. If the primary tear is located in the lesser curvature of the transverse arch, hemiarch replacement is one of choice instead of total arch replacement. Moon et al. reported that hemiarch replacement was not associated with increased operative risk compared with ascending aortic replacement [15]. In our series, we resected the primary tears and the distal anastomosis was performed under deep hypothermic circulatory arrest even in the ascending aortic replacement. As a result, hemiarch replacement was not more invasive than ascending aortic replacement in terms of CPB time and cerebral perfusion time. In this series, we performed partial arch replacement in seven cases. If the primary tear is located in the lesser curvature of the transverse arch, the partial arch is one of good choice, in addition to hemiarch replacement. The suture line of the distal anastomosis of partial arch replacement is shorter than that of hemiarch replacement and cerebral perfusion time was similar between hemiarch and partial arch replacement (Table 2). The conclusions are limited by some characteristics of this study. These include the retrospective and uncontrolled nature of this series, that it is based on a single institution's experience, and the small size of the patient population. Although, in this study, the extent of aortic resection and the sites of arterial return did not significantly differ in the obliteration of the false lumen of the descending aorta in comparison with ascending aortic replacement, larger cohorts might allow a statistically significant difference. Further clinical studies are needed.
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Abstract
1. Introduction
