Ann Thorac Surg 2000;70:558-561
© 2000 The Society of Thoracic Surgeons
Original articles: cardiovascular
Complications associated with clamping the aorta between the left common carotid artery and left subclavian artery
Toshihiko Ueda, MDa,
Hideyuki Shimizu, MDa,
Katsumi Moro, MDa,
Hankei Shin, MDa,
Ryouhei Yozu, MDa,
Ichiro Kashima, MDa,
Shiaki Kawada, MDa
a Department of Cardiovascular Surgery, School of Medicine, Keio University, Tokyo, Japan
Address reprint requests to Dr Ueda, Department of Cardiovascular Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, 160–8582 Tokyo, Japan
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Abstract
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Background. Hypothermic circulatory arrest using a left thoracotomy has recently been recommended for repair of distal arch lesions to prevent the atheroembolism that often results from clamp injury. The recommendation holds even for cases in which aortic cross-clamping between the left common carotid artery and left subclavian artery is possible.
Methods. Over the last 16 years, 69 patients underwent repair of the distal arch or descending thoracic aorta using distal perfusion with the proximal aortic clamp placed between the left common carotid and left subclavian artery. The average age of the patients was 61 ± 12 years; 18 of them (26%) were older than 70 years. Forty-four patients (64%) had atherosclerotic true aneurysms.
Results. The surgical procedures used included patch closure of saccular aneurysms in 20 patients (29%) and graft replacement in 47 (71%). The left subclavian artery was reattached in 7 patients (10%). Although there were 3 hospital deaths (4%), no cerebral complications occurred aside from temporary neurologic dysfunction in 4 patients (6%).
Conclusions. An acceptably low incidence of cerebral complications is associated with cross-clamping the aorta between the left common carotid artery and left subclavian artery.
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Introduction
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In recent years, a rapid increase in the prevalence of atheroemboli caused by cross-clamping of the ascending aorta during open heart surgery has been observed [1]. In repair of the distal aortic arch or proximal descending aorta, deep hypothermic circulatory arrest with or without retrograde cerebral perfusion by a left thoracotomy has been recommended to prevent atheroembolism caused by clamp injury of the aortic intima [2, 3].
On the other hand, aortic cross-clamping distal to the left common carotid artery appears to provide relatively safe circulatory conditions. Kay and associates reported that patients in their series who had undergone repair of the distal aortic arch by simple aortic cross-clamping between the brachiocephalic artery and left common carotid artery suffered no postoperative stroke [4]. Their excellent results may, however, have been due to the operators’ skilled surgical techniques, which may have enabled shorter aortic cross-clamp times.
Is hypothermic circulatory arrest using a left thoracotomy for repair of distal arch lesions advisable even in cases in which an aortic cross-clamp between the left common carotid artery and left subclavian artery is technically possible? This retrospective study addresses that question.
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Material and methods
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In 69 patients undergoing repair of the distal aortic arch or descending thoracic aorta between June 1982 and October 1998, a proximal aortic cross-clamp was placed between the left common carotid artery and left subclavian artery (Table 1). This technique was used for patients with true aneurysms in whom proximal extension of disease was more than 1 cm distant from the origin of the left common carotid artery. Patients with type B aortic dissections were also selected for this technique in cases in which the proximal arch was not dilated. During the same period, 166 patients underwent aortic arch repair using selective cerebral perfusion.
Patient characteristics
Patients ranged in age from 31 to 85 years with an average age of 61 ± 12 years. Eighteen patients (26%) were older than 70 years, and 21 (30%) were female. The pathology of the aneurysms included true aortic aneurysm in 47 patients (68%); 44 (64%) of the 47 were athelosclerotic . Aortic dissection was noted in 19 patients (28%). Seven patients (10%) had undergone a prior aortic operation. Preoperative shock was present in 1 patient (1%) who had a ruptured acute Stanford type B aortic dissection. Circulatory conditions were stable in the remaining 68 patients, including 1 with an aortoesophageal fistula and 3 with hemoptysis.
One patient had a history of transient ischemic attack, and one other had medically controlled epilepsy. No significant history of cerebral disorders was present in the remaining patients. A preoperative computed tomography scan or magnetic resonance image of the brain was performed in 22 patients (32%). Most of those patients were operated on after 1992, before which time indications for these studies had been limited to patients with a history of cerebrovascular disease. Among these 22, 10 patients (45%) had studies showing an old cerebral infarction while 3 (14%) had studies showing severe brain atrophy. Eight patients (12%) had coronary artery disease revealed by coronary angiography. Three of the 8 underwent catheter intervention preoperatively. Renal dysfunction (serum creatinine > 2.0 mg/dl or a glomerular filtration rate < 30 ml/min) was present in 4 patients (6%). In addition, 12 patients (17%) suffered left recurrent nerve palsy.
Surgical procedures
A median incision was necessary to facilitate exposure of the proximal arch in patients with a large proximal and anterior aneurysmal protrusion. A median approach was also indicated in patients in whom pleural adhesion was anticipated. When the aneurysms involved less than one half proximally of the descending thoracic aorta, a T-shaped thoracotomy was performed. Whenever the aneurysms involved the distal descending thoracic aorta, both a median sternotomy and a left thoracotomy were performed. Whenever the anterior and proximal protrusion of the aneurysms were not prominent, the operations were performed using a left thoracotomy.
During aortic cross-clamping, distal bypass techniques were carried out in all patients. In the first few years of the series, a temporary external long bypass or a shunt tube was used (32%) [5]. In more recent years, an aortofemoral bypass or left atriofemoral bypass using centrifugal pump, total cardiopulmonary bypass, and femoral venoarterial partial cardiopulmonary bypass were performed [6].
Once the distal bypass was established, the left subclavian artery, the proximal aorta between the left common carotid artery and left subclavian artery, and the distal aorta were cross-clamped. The left subclavian artery was clamped using a tourniquet or an ordinary vascular clamp. Fogarty clamps were used for cross-clamping the aorta in most patients.
A Dacron patch closure was primarily performed for repair of saccular aneurysms, especially in the earlier cases in this series. A prosthetic graft replacement was performed for the other aneurysms. The left subclavian artery was reattached using a graft interposition technique. Reattachment of intercostal arteries was done by a bevel-fashioned distal aortic anastomosis.
In order to prevent atheroemboli, special care was taken not to move the proximal clamps before unclamping. The proximal suture line was carefully irrigated by flashing saline solution inside the graft before releasing the cross-clamp. The left subclavian artery was the first to be unclamped. The surgeon then reclamped the artery with his fingers while any backbleeding was aspirated. Next the proximal aortic clamp was released while manually controlling any bleeding through the graft. After a certain amount of blood had been evacuated along with debris, the graft was cross-clamped and the left subclavian artery opened.
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Results
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Surgical approaches for aneurysm included left thoracotomy in 28 patients (41%), combined median sternotomy and left thoracotomy in 21 (30%), and T-shaped thoracotomy in 17 (25%) (Table 2). The aneurysm was approached via the median sternotomy alone in 1 patient. An aortic occluder balloon was used for the distal clamp in this patient. A temporary external long bypass or a shunt tube was used in 22 patients (32%), aortofemoral bypass or left atriofemoral bypass with a centrifugal pump in 10 patients (14%), total cardiopulmonary bypass in 4 (6%), and femoral venoarterial partial cardiopulmonary bypass in 33 (48%) (Table 3).
Patch closure was performed in 20 patients (29%). The remaining 49 patients (71%) underwent prosthetic graft replacement; of those, more than half of the descending thoracic aorta was replaced in 19 (28% of the total patient group). The left subclavian artery was repaired in 7 patients (10%), and reattachment of the intercostal arteries was performed in 10 patients (14%).
The time required for surgery ranged from 200 to 580 minutes (mean, 371 ± 91 minutes). The extracorporeal circulation time ranged from 38 to 198 minutes (mean, 102 ± 41 minutes). The aortic cross-clamp time ranged from 34 to 188 minutes (mean, 89 ± 36 minutes). Mean transfused blood components totalled 16 ± 13 U. Platelet transfusion was done in 23 patients (33%). Seven patients did not require a blood transfusion (10%).
One patient who experienced transient shock during the operation as a result of explosion of the aortic occluder balloon did not regain consciousness until postoperative day 2. All remaining patients regained consciousness within 24 hours postoperatively. Temporary neurologic dysfunction, as defined by Ergin and associates [6], was seen in 4 patients (6%) (Table 4). Delayed awakening was observed in 1 of those patients, convulsion in 1, and delirium in 2. All of these 4 patients were referred to neurologists and subsequently underwent brain CT scan, which failed to detect any lesion associated with symptoms. No patient suffered stroke or permanent global brain dysfunction. One patient with medically controlled epilepsy experienced a seizure, and postoperative paraplegia or paraparesis occurred in 2 patients (3%).
Thirty-nine patients (57%) were weaned from the ventilator within 24 hours postoperatively. Although 63 patients (91%) had been weaned by 72 hours, 5 patients still had not been weaned by day 7 (7%). Three patients suffered pneumonia or adult respiratory distress syndrome (4%).
One patient with no coronary lesion evident on angiography presented with acute inferior myocardial infarction, probably as a result of a spasm of the right coronary artery. No cases of low cardiac output syndrome were observed. Reexploration and drainage were required in 2 patients (3%) for late cardiac tamponade.
Other postoperative complications included renal failure necessitating hemodialysis or peritoneal dialysis in 2 patients (3%), serum hepatitis in 2 (3%), and new left recurrent nerve palsy in 23 of 57 patients (40%). In addition, catastrophic mediastinitis occurred in a 62-year-old woman with aortoesophageal fistula.
Three patients died in the hospital (4%). The patient with mediastinitis died on postoperative day 12. A 68-year-old woman who had been weaned from the ventilator on postoperative day 2 suffered refractory pneumonia and died of respiratory failure on postoperative day 21. Severe pancreatitis occurred in a 73-year-old male patient who had previously suffered paraplegia. He died of respiratory failure on postoperative day 78.
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Comment
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In their series, Ergin and associates reported that strokes due to emboli occurred in 11.8% of patients who had undergone an aortic arch repair using hypothermic circulatory arrest [7]. They observed furthermore that the prevalence of stoke was higher in patients with descending aorta and distal arch replacement than in those with total arch replacement. Okita and associates reportedly performed 148 aortic arch operations using retrograde cerebral perfusion and found that stroke occurred in 7% of patients undergoing the procedure by way of left thoracotomy and in only 2% of patients undergoing the procedure by way of median sternotomy [8].
We also performed hypothermic circulatory arrest using a left thoracotomy in patients for whom the technique was feasible [9], despite the fact that atheromatous debris is believed to fall into the ascending aorta and proximal aortic arch because patients are lying in a left decubitus position. Despite this concern, and despite the fact that 64% of the patients in our series had atherosclerotic aneurysms and that 26% were older than 70 years, only 6% of the total study population presented with postoperative temporary neurologic dysfunction. No patient suffered stroke or global cerebral dysfunction.
In our clinical experience of patients with true aneurysms involving the distal aortic arch or proximal descending aorta, it is not uncommon to encounter cases in which aortic cross-clamping between the left common carotid artery and left subclavian artery is technically possible. We recommend employing this technique whenever proximal extension of the disease is more than 1 cm distant from the origin of the left common carotid artery. In most patients with Stanford type B aortic dissection, there is also room to clamp the distal aortic arch. Whenever proximal or anterior protrusion of the aneurysm is prominent, a combined median sternotomy and left thoracotomy or a T-shaped incision is recommended [10].
In their series, Yamashita and associates reported that distal arch aneurysms could be repaired more safely by retrograde cerebral perfusion with a left thoracotomy than by aortic cross-clamping and left heart bypass or by retrograde cerebral perfusion with an open-door thoracotomy [11]. Only a small number of patients (5 of 14) in the former group had an atherosclerotic aneurysm, whereas all the patients in the latter two groups had an atherosclerotic aneurysm. Furthermore, no patient was more than 70 years old and only 3 patients underwent reconstruction of the left subclavian artery in the former group. Nevertheless, the prevalence of postoperative complications was not negligible.
We agree with previous researchers that deep hypothermia is an extremely effective spinal preservation technique for patients undergoing extended repair of the thoracoabdominal aorta [12]. However, as Crawford and associates have noted, the incidence of complications—pulmonary complications in particular—was remarkably high even in low-risk patients who had undergone distal arch and descending aortic repair with hypothermic circulatory arrest by a posterolateral exposure [2]. In contrast, pulmonary complications occurred in only 4% of our patients, and more than 90% were weaned from the ventilator within 3 days of the operation. No patient presented with low cardiac output syndrome. The most prevalent complication associated with our procedure was left recurrent nerve palsy, which might have been avoided had a circulatory arrest and no-clamp method been used. However, the incidence of this complication has not been clearly established by the previously cited studies.
The incidence of cerebral complications associated with repair of the distal aortic arch and descending aorta is shown to be acceptably low when cross-clamping the aorta between the left common carotid artery and left subclavian artery using ordinary normothermic distal perfusion techniques.
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References
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Accepted for publication December 31, 1999.
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Abstract
Introduction
