Ann Thorac Surg 2004;77:1448-1449
© 2004 The Society of Thoracic Surgeons
Case report
Lethal thrombus in the carotid artery during operation for acute aortic dissection with cerebral malperfusion
Kazuhito Imanaka, MDa*,
Motonobu Nishimura, MDa,
Ayumu Masuoka, MDa,
Masanori Ogiwara, MDa,
Masaaki Kato, MDa,
Haruhiko Asano, MDa,
Shunei Kyo, MDa
a Department of Cardiovascular Surgery, Saitama Medical School, Saitama, Japan
Accepted for publication April 28, 2003.
* Address reprint requests to Dr Imanaka, Department of Cardiovascular Surgery, Saitama Medical School, 38 Morohongo, Moroyama-machi, Iruma-gun, Saitama 350-0495, Japan
e-mail: imanaka{at}saitama-med.ac.jp
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Abstract
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A drowsy patient with acute type A aortic dissection and cerebral malperfusion required emergency operation. Because the right carotid artery was totally obstructed, cerebral perfusion was first restored by cannulating it and the left femoral artery before midline sternotomy. However, a long fresh thrombus was found flowing backward from the obstructed carotid artery. This thrombus was removed, and both arteries were connected through a Y-shaped extracorporeal circulation circuit to reperfuse the brain. During the subsequent aortic procedure, both arteries were used for arterial inflow. Such thrombi can cause grave postoperative neurologic dysfunction. Carotid artery cannulation is mandatory in such cases.
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Introduction
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In patients with acute aortic dissection and cerebral malperfusion, neurological disorders tend to get much worse after an emergency surgery. In such a situation, thrombosis in the carotid artery, if present, causes more severe cerebral hypoperfusion or embolization in distal cerebral arteries during and after repair of the aorta, and may result in grave brain damage.
A 58-year-old man experienced sudden severe back pain. An acute type A aortic dissection was diagnosed, and he was transferred to our hospital for surgical repair 6 hours after onset. On admission, the patient was drowsy and had left hemiplegia. Blood pressure was 160/60 mm Hg in the left arm but 80/50 mm Hg in the right. A duplex scan revealed that the right carotid artery, having been totally obstructed, was affected by the dissection. Pericardial effusion was absent. Because obvious signs of mesenteric malperfusion were also present, however, emergency operation was indicated. We recanalized the right carotid artery first. Just after the induction of general anesthesia, the right carotid artery and the left femoral artery were exposed, and heparin was injected. The femoral artery was free of dissection, and an arterial cannula was introduced in the usual fashion. The right carotid artery was then incised, and another arterial cannula was inserted into the true lumen. However, a long fresh thrombus, 7 cm in length and 5 mm in diameter, was carried backward into the cannula. This thrombus was removed, and the femoral artery and right carotid artery were linked through a Y-shaped circuit of the extracorporeal circulation (ECC). Arterial blood started to flow through this shunt from the femoral artery to the carotid artery (Fig 1),
and then a midline sternotomy was made. During the following aortic procedure, both arteries, in which the cannulas were already in place, were used for the arterial inflow of the ECC. The perfusion temperature was rapidly decreased, and replacement of the ascending aorta and hemiarch and extraanatomic bypass from the aorta to the right carotid artery were concomitantly performed.The patient regained consciousness on the same day, and mechanical ventilation was discontinued on the next day. His consciousness became clear, and he recovered partially from the left hemiplegia. No new neurologic deficit was observed. The remaining postoperative course was uneventful.
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Fig 1. Diagram of the method. Before a midline sternotomy, the obstructed right carotid artery and the left femoral artery were exposed. After the thrombus was removed, cannulas were inserted, and the two arteries were connected through a Y-shaped circuit of the extracorporeal circulation, with a clamp just proximal to the bifurcation (*). Arterial blood started to flow from the femoral artery to the carotid artery (arrows).
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Comment
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Malperfusion, especially to the heart or to the brain, is a life-threatening complication of aortic dissection [1]. Emergency aortic operation is often inevitable even in the presence of cerebral malperfusion, although neurologic disorders tend to deteriorate. This case clearly highlighted important aspects of such situations. We encountered a long thrombus in the carotid artery that was undetectable with the duplex scan. Without cannula placement in the carotid artery, this thrombus would have been missed, and severe brain damage may have resulted from more serious hypoperfusion to the right cerebral hemisphere during ECC and from persistent malperfusion or embolization in the distal cerebral arteries after repair of the aorta. Direct carotid artery cannulation prevented further brain damage, although preexisting deficits could not be completely eliminated. In view of this hazardous thrombus, palliative procedures, central aortic repair alone [2], and subclavian or axillary artery cannulation [3] are inappropriate. A cannula must be placed into the obstructed carotid artery, and thrombi, if present, must be removed. To avoid possible recurrent malperfusion, moreover, that carotid artery should be reconstructed separately at the cannulation site.
Another problem was the timing and method of recanalization of the carotid artery. Because the brain is highly vulnerable to ischemia, it is unclear whether early reperfusion is beneficial. In our opinion, it should be attempted before the initiation of ECC. The earliest possible timing is just after the induction of general anesthesia in the operating room, because puncturing the obstructed true lumen is very difficult and because recanalizing the carotid artery before removing a potentially lethal thrombus is even dangerous. This method is reliable for removing possible thrombi and for promptly recanalizing the true lumen, and the cannulas, once in place, can be used during the following aortic procedure. Thus, this method is advantageous and represents little difference in surgical invasiveness or operation time. In patients with coexistent pericardial tamponade, however, midline sternotomy and pericardial fenestration should be performed first because systemic heparinization is necessary.
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References
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- Cambria R.P., Brewster D.C., Gertler J., et al. Vascular complications associated with spontaneous aortic dissection. J Vasc Surg 1988;7:199-209.[Medline]
- Hughes J.D., Bacha E.A., Dodson T.F., Martin T., Smith R.B., III, Chaikof E.L. Peripheral vascular complications of aortic dissection. Am J Surg 1995;170:209-212.[Medline]
- Neri E., Massetti M., Capannini G., et al. Axillary artery cannulation in type A aortic dissection operations. J Thorac Cardiovasc Surg 1999;118:324-329.[Abstract/Free Full Text]
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Abstract
Introduction
