| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 2002;74:S1853-S1856
© 2002 The Society of Thoracic Surgeons
a Department of Thoracic and Cardiovascular Surgery, Saga Medical School, Saga, Japan
* Address reprint requests to Dr Ohtsubo, Department of Thoracic and Cardiovascular Surgery, Saga Medical School, 5-1-1 Nabesima, Saga-City 849-8501 Japan
e-mail: ootsubt2{at}post.saga-med.ac.jp
Presented at the Aortic Surgery Symposium VIII, May 2–3, 2002, New York, NY.
Abstract
BACKGROUND: The appropriate surgical strategy for patients with an arch tear in acute type A dissection remains controversial. We retrospectively compared surgical results after hemiarch as compared with transverse aortic arch replacement in patients with an arch tear in acute type A dissection.
METHODS: The records of 88 patients who consecutively underwent graft replacement for acute type A dissection between 1989 and 2001 were reviewed. The patients were divided into three groups: patients with ascending aortic replacement (group AS, n = 41), those with hemiarch replacement (group HA, n = 23), and those with transverse arch replacement (group AR, n = 24). Operative mortality and morbidity and late outcome were compared among the three groups.
RESULTS: The overall early (30 day) mortality was 11.3% (10/88), and in-hospital mortality was 14.7% (13/88). In-hospital mortality in groups AS, HA, and AR were 7.3%, 8.6%, and 33.3%, respectively (p = 0.011). Cardiopulmonary bypass, circulatory arrest, and operation times were significantly shorter in group HA than in group AR (p < 0.001). A smaller amount of intraoperative transfusion of red blood cells (p = 0.0006) and fresh-frozen plasma (p = 0.0003) was needed in group HA than in group AR, and postoperative bleeding during the first 24 hours postoperatively was significantly less in group HA than in group AR (p = 0.0028). The incidence of postoperative coma did not differ among the three groups (p = 0.89), nor did the incidence of postoperative patent false channel in the descending thoracic aorta (p = 0.57). Actuarial survival rates after 5 years were significantly better in group HA (91.3% ± 5.9%) than in group AR (44.4% ± 14.3%, p = 0.018). Freedom from reoperation on the distal aorta within 5 years did not differ among the groups (p = 0.46).
CONCLUSIONS: Hemiarch replacement for acute type A dissection demonstrated favorable early and late outcome. The extent of graft replacement influenced surgical mortality and morbidity. Whenever the intimal tear is located in the lesser curvature of the transverse arch, hemiarch replacement is recommended to improve overall operative mortality and morbidity.
In acute type A dissection, the selection of a procedure for patients who have an arch tear remains controversial. Surgical results of total arch replacement have improved recently [1, 2], but this has been a challenging procedure for preoperatively compromised patients. Hemiarch replacement facilitates resection of the arch tear when it is localized in the lesser curvature of the transverse arch. Hemiarch repair preserves all the ostia of the arch vessels and avoids the need for their reconstruction. These features may contribute to decreasing surgical morbidity and mortality that would otherwise be caused by extended arch replacement. However, details of early and late outcome of hemiarch replacment for acute type A dissection have not been well documented.
The objective of this study was to evaluate our surgical experience of hemiarch replacement for acute type A dissection and to retrospectively compare mortality and morbidity between hemiarch and extended transverse arch replacement in those who needed resection of an arch tear. This study also attempted to determine whether or not the extent of surgical resection influences the early and late outcome after surgery for acute type A dissection.
Material and methods
Indications for procedures
The type of procedure was chosen based on the location of the intimal tear. Hemiarch replacement was done in cases with primary tears localized in the lesser curvature and anterior wall of the transverse aortic arch distal to the innominate artery. When the tear was seen in the anterior wall, it was required that there be at least 10 mm of intact intima between the tear and the orifices of the arch vessels for a patient to undergo hemiarch repair. If the tears extend to the orifices of arch vessels and the posterior wall of the arch, total arch replacement was performed. Other indications for total arch replacement were: (1) tear located at the proximal descending aorta, (2) rupture or impending rupture of the dissected arch, (3) coexisting arch aneurysm, (4) Marfan syndrome. Ascending aortic replacement was done when the tear was localized to the ascending aorta. Root replacement was done in cases with a destroyed aortic root or preexisting root pathology such as Marfan syndrome.
Technique of hemiarch replacement and extended arch replacement
Cardiopulmonary bypass was established between the femoral artery and the right atrium. Axillary perfusion was added when malperfusion was found preoperatively. Cardiac arrest was obtained with cold blood cardioplegia. Under profound hypothermic circulatory arrest, the transverse aortic arch was opened and inspected closely. The lesser curvature of the aortic arch, including the primary tear, was resected. Antegrade cerebral perfusion was not routinely used for hemiarch replacement.
When prolonged circulatory arrest was expected (n = 5, 21.7%), antegrade selective cerebral perfusion at 10 mL/kg/min was used. Reinforcement of the aortic stumps was carried out using felt strips both inside and outside the aortic wall, and gelatin resorcin formol (GRF) glue was used to obliterate the false lumen. A beveled incision was made for the distal end of a vascular graft to replace the arch. After completion of the open distal anastomosis, the graft was cross-clamped, and antegrade systemic perfusion was resumed through a side branch of the vascular graft.
The technique of extended arch replacement is identical to the method advocated by Kazui et al [1]. A minor difference in cerebral protection from Kazui’s method is that we perfuse all three arch vessels for the possible benefit of the posterior cerebral vessels and for spinal cord protection.
Patients and methods
In our institution, a consecutive series of 88 emergency operations were performed for acute type A aortic dissection within 2 weeks from onset of symptoms between January 1989 and October 2001. There were 32 male and 56 female patients, aged 20 to 89 years (median 66.2 ± 11.1) including 4 Marfan patients and 3 octogenarians. Complete resection of primary tears was achieved in 86 patients (97.7%); the exceptions were those patients whose primary tear was not found despite inspection under circulatory arrest.
Group AS was defined as 41 patients who underwent ascending aortic replacement with a tube vascular graft, including 2 with concomitant root replacements. Group HA was defined as 23 patients who underwent hemiarch replacement with a tailored tube graft with a beveled distal end, replacing the underside of the arch (and resecting the tears). Group AR was defined as 24 patients who underwent transverse aortic arch replacement with a branched vascular graft, and included 4 patients with concomitant root replacements. Preoperative risk factors are summarized in Table 1 and there were no significant differences among the three groups.
|
|
2 analysis, and Fisher’s test, if necessary. Differences were considered significant at the level of p < 0.05. Actuarial survival rates and reoperation-free rates were estimated by the Kaplan-Meier method, and statistical differences were analyzed using the log-rank test. All statistical analysis was performed with Statview 5.5 (SAS Inc., Chicago, IL). Data are expressed as medians ± SD. Results
The overall early (30-day) mortality was 11.3% (10/88), and in-hospital mortality was 14.7% (13/88). In-hospital mortality in groups AS, HA, and AR was 7.3%, 8.6%, and 33.3%, respectively. Group HA had significantly lower mortality than group AR (p = 0.01). The causes of hospital death included low output syndrome in 5, infection in 3, ruptured abdominal aortic aneurysm in 1, bowel necrosis in 1, global cerebral infarction in 2, and disseminated intravascular coagulopathy in 1 patient.
As seen in Table 2, cardiopulmonary bypass (CPB), circulatory arrest, and operation times were significantly shorter in groups AS and HA than in group AR (p < 0.001). Selective cerebral perfusion was used only in 5 patients in groups AS and HA, but in all patients in group AR. Median SCP times in groups HA and AR were 29 and 106 minutes, respectively. A smaller amount of intraoperative transfusion of red blood cells (p = 0.0006) and fresh-frozen plasma (p = 0.0003) was needed in AS and HA groups than in group AR. The amount of bleeding from chest drainage during the first 24 hours after surgery was significantly less in groups AS and HA than in group AR (p = 0.0028). As also seen in Table 2, the groups did not differ in the incidence of postoperative coma, focal neurologic deficit, or patent false channel in either the descending thoracic or the abdominal aorta.
As for late outcome, actuarial survival rates (including early death) at 5 years were significantly better in group HA (91.3% ± 5.9%) and in group AS (86.8% ± 6.8%) than in group AR (44.4% ± 14.3%, p = 0.018). During follow-up after discharge, 16 patients died; 13, however, died of noncardiovascular events, suggesting that late death was not directly related to the type of surgical procedure.
Seven patients needed reoperation on the residual aorta, including 3 patients with Marfan’s syndrome. The rates of freedom from reoperation on the distal aorta at 5 years in groups AS, HA, and AR were 96.4% ± 3.5%, 93.8 ± 6.3 and 100% ± 0.0%. respectively. There was no significant difference between the groups (p = 0.86).
Comments
The appropriate surgical approach for patients with an arch tear in acute type A dissection has remained controversial [3, 4]. Unresected arch tears may cause bleeding from suture lines, postoperative arch rupture, and cerebral malperfusion. Extensive transverse arch replacement has the benefit of complete resection of the tear and the dissected arch wall, but it has been a challenging procedure with a high mortality rate of 20% to 30% [4–6]. Hemiarch replacement allows resection of arch tears extending not only onto the lesser curvature, but also over a broad area of the anterior wall of the transverse aortic arch. Even if the distal end of the primary tear extends to the level of the subclavian artery, an anterior arch tear can be resected using hemiarch replacement. Therefore, quite a few patients with arch tears can benefit from hemiarch replacement [7–9]. Hemiarch replacement preserves the ostia of the three arch vessels and avoids the need for arch vessel reconstruction. A beveled tube graft replacement can easily be incorporated under circulatory arrest, and therefore, hemiarch replacement results in a low mortality and morbidity comparable with ascending aorta replacement. In this study, the hospital mortality of ascending aorta replacement and hemiarch replacement was 7.1% and 8.6%, respectively.
Some investigators have advocated that extended total arch replacement should be performed irrespective of location of primary tears as the operative strategy in acute type A dissection [10, 11]. Whether acute type A dissection should always be treated by transverse arch replacement or by a procedure based on the location of the tear is a legitimate question. In this study, the extent of surgical resection influenced mortality and morbidity. Our experience showed that CPB, circulatory arrest, and operation times were shortened significantly in patients with hemiarch replacement and ascending aorta replacement compared with transverse arch replacement. The need for and duration of extracorporeal cerebral perfusion was significantly less in patients with hemiarch replacement compared with arch replacement. Prolonged cerebral perfusion for brain protection increases postoperative neurologic morbidity [12]. From our institutional experience, it is difficult to justify performance of transverse arch replacement for all patients with acute type A dissection.
A patent false channel in the distal aorta after surgery for acute type A dissection increases the risk of reoperation and late vascular events [6, 13–15]. In our institution, both patency of the distal false channel and reoperation rate did not differ among the types of procedures. The comparable incidence of patency of the distal false channel and reoperation rate are possibly explained by the fact that complete tear resection was accomplished in 97.6% of patients in this study. It is suggested that late vascular events are influenced not by the extent of resection but by the feasibility of primary tear resection. Selective use of hemiarch and transverse arch replacement allowed aggressive resection of arch tears while decreasing overall late vascular events.
In summary, the mortality and morbidity of hemiarch replacement was as low as that of ascending aortic replacement. Hemiarch replacement (in comparison with extended arch replacement) demonstrated a lower mortality; shorter CPB, circulatory arrest, and operation times; less bleeding; a decreased requirement for blood transfusion; and a comparable incidence of a patent distal false channel and of late vascular events. Whenever the intimal tear is localized in the lesser curvature of the arch, hemiarch replacement is recommended to improve overall surgical results of acute type A dissection.
References
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
