Ann Thorac Surg 2004;78:1465-1467
© 2004 The Society of Thoracic Surgeons
Case report
Atresia of the Right Vertebral Artery in a Patient with Acute Aortic Dissection
Steffen Altmann, MDa,
Steffen Fröhner, MDa,
Anno Diegeler, MDa,
Paul P. Urbanski, MDa,*
a Herz- und Gefaess-Klinik, Bad Neustadt, Germany
Accepted for publication July 10, 2003.
* Address reprint requests to Dr Urbanski, Herz- und Gefaess-Klinik, Salzburger Leite 1, 97616 Bad Neustadt, Germany
p.urbanski{at}herzchirurgie.de
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Abstract
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A 49-year-old man had severe neurocognitive dysfunction after urgent operation for acute type A aortic dissection. Complete aortic arch replacement with single reimplantation of the arch branches was performed with the patient under deep hypothermic circulatory arrest. Retrospectively, my colleagues and I consider the atresia of the right vertebral artery to be responsible for this complication and discuss whether knowledge of the anomaly and adapting the operative strategy accordingly would have improved the neurologic outcome.
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Introduction
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The described case of an atresia of the right vertebral artery emphasizes the necessity of adequate preoperative assessment, which could improve neurologic outcome. A more individualized surgical strategy would have been chosen with a better preoperative diagnosis.
In a 49-year-old man with chronic arterial hypertension and severe pain, an acute type B aortic dissection was diagnosed by computed tomographic (CT) scan in another hospital. A follow-up echocardiogram showed a slightly progressive pericardial effusion.
After the patient was transferred to our clinic, a contrast-enhanced multislice CT was performed that showed retrograde extension of the dissection into the ascending aorta. On the basis of this finding, an acute type A aortic dissection with an entry in the dilated aortic arch was diagnosed, and the patient underwent urgent operation.
A transverse anterior bilateral thoracotomy in the third intracostal space, which allows excellent exposure of the aortic arch and its branches [1], was chosen. Cardiopulmonary bypass was established by cannulation of the right common femoral artery and the right atrium. After the body temperature was cooled to 18°C, the ascending aorta and the aortic arch were opened under circulatory arrest. In addition to ice packs placed around the head, thiopental and cortisone were used for pharmacologic brain protection. An acute aortic dissection with a large intimal tear in the aortic arch at the level of the left subclavian artery was found. Furthermore, there was antegrade extension into the descending aorta and retrograde extension into the ascending aorta.
After resection of the ascending aorta and of the aortic arch, complete replacement of the aortic arch was performed, beginning with distal end-to-end anastomosis to the descending aorta by using a 20-mm woven collagen-coated polyester prosthesis (InterGard; InterVascular, La Ciotat, France). The anastomosis was sutured in a running fashion with 4-0 polypropylene, including an additional external felt strip to reinforce the dissected aortic wall. Implantation of the innominate artery and of the left common carotid artery into the aortic arch prosthesis was performed with a 16 x 8-mm bifurcation prosthesis. Then the aortic arch prosthesis was cannulated, and after transverse clamping of the prosthesis proximal to the reimplanted branches, the antegrade perfusion with slow rewarming of body temperature was started. The duration of circulatory arrest was 62 minutes.
After perfusion of the coronary arteries with cold crystalloid cardioplegic solution, the proximal aortic repair was performed with a 24-mm collagen-coated Dacron prosthesis with a 10-mm side branch (Hemabridge; InterVascular). Because the aortic root was neither dissected nor dilated, the proximal end-to-end anastomosis was accomplished at the level of the sinotubular junction with continuous 4-0 polypropylene sutures and without additional reinforcement.
After completion of the anastomosis between both grafts, the aortic clamp was removed. Cross-clamping time, including circulatory arrest, was 118 minutes. Finally, end-to-end anastomosis between the side branch of the Hemabridge prosthesis and the left subclavian artery was performed (Fig 1). Weaning from cardiopulmonary bypass (with a duration of 312 minutes) was uneventful.
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Fig 1. Schematic view of the surgical site. (BC = innominate artery; LCC = left common carotid artery; LS = left subclavian artery; RV = right vertebral artery.)
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After extubation on the fourth postoperative day, the patient had severe neurocognitive dysfunction with a complete deficit of visual recognition. Subsequent CT of the neurocranium showed slight hypodense changes in the circulation area of the left and, especially, the right posterior cerebral artery. A contrast-enhanced magnetic resonance angiography of the aortic arch was made to verify the postoperative outcome and to check for possible causes of the neurologic symptoms. It showed a regular postoperative result after replacement of the ascending aorta and of the aortic arch with new insertion of all supraaortic vessels. In addition, a complete atresia of the right vertebral artery was diagnosed and assumed to be the cause of the cerebral ischemia (Fig 2). Because of the localization of the ischemic injury in the catchment area of the occluded right vertebral artery, an embolic cause of the cerebral ischemia seems unlikely. The prolonged duration of circulatory arrest is a more probable cause. However, my colleagues and I believe that in this patient the circulation area of the right vertebral artery had a collateral flow by the enlarged left vertebral artery rather than by the right carotid artery. The delay in revascularizing the left subclavian artery during reperfusion is therefore the most probable reason for the intraoperative cerebral ischemia.
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Fig 2. Postoperative contrast-enhanced magnetic resonance angiography shows a regular position of the reimplanted arch vessels and atresia of the right vertebral artery, with a compensatorily enlarged left vertebral artery (arrows).
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On the 19th postoperative day, the patient was transferred to a neurologic rehabilitation center. Under intensive neurologic care, the patient gradually regained visual recognition. At 12-month follow-up, the patient was living at home. However, because of severe organic personality disorders, with the extent of the remaining visual impairment and neurocognitive brain dysfunction difficult to quantify, the patient requires the permanent care of his wife.
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Comment
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Despite improved surgical techniques for complex operations on the aortic arch, optimal cerebral protection is still a matter of controversy [2, 3]. The case described underlines the significance of adequate preoperative diagnostics, which is possible without delay of operation or increased risk, even under emergency conditions. Such diagnostics not only reveal changes due to dissections, but also detect unforeseeable and rare pathologic conditions of the arch vessels [4, 5]. Such findings (as, in our case, the complete atresia of the right vertebral artery) would have markedly influenced the decision for an individual surgical strategy, for example, by earlier reimplantation of the left subclavian artery, use of selective cerebral perfusion, or both. The use of an arch prosthesis with 4 side branches would also be advantageous because of the decreased time needed for separate reimplantation of the arch vessels.
In our opinion, thorough preoperative diagnostics, even in the case of an emergency, are required for the planning of an aortic arch operation. Knowledge of the condition of the arch vessels helps in choosing the individual operative strategy and more effective cerebral protection, especially because a sufficient collateral pathway in the area of the circle of Willis is not always present [6].
In aortic dissections, the diagnostic tool best suited for the imaging of arch vessels under emergency conditions is by multislice CT angiography, which is not invasive and gives a very good view of these vessels. The scan range for thoracic CT angiography should be enlarged toward the middle neck area. A higher amount of contrast medium is not necessary, and the scan time increases for only a few seconds. Thin maximum intensity projection reconstructions are required to show the vessel pathway accurately. CT angiography of the supraaortal branches is also possible with single-slice spiral CT scans, which provide thicker slices and a slight reduction in detail resolution.
The case described here subsequently caused us to add an examination of the arch vessels to preoperative thoracic CT angiography for diagnosis of acute aortic dissection. In addition, we recently started to cannulate the left common carotid artery if a complex aortic arch repair is necessary [7]. Thereby a partial cerebral perfusion is retained during circulatory arrest.
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References
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- Kouchoukos NT, Rokkas CK. Single-stage extensive replacement of the thoracic aorta: the arch-first technique. J Thorac Cardiovasc Surg. 1999;117:99–105[Abstract/Free Full Text]
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- Hagl C, Ergin MA, Galla JD, et al. Neurologic outcome after ascending aorta-aortic arch operations: effect of brain protection technique in high-risk patients. J Thorac Cardiovasc Surg. 2001;121:1107–1121[Abstract/Free Full Text]
- Ad N, Lee P, Cox JL. Type A aortic dissection with associated anomaly of the carotid and vertebral vessels. J Thorac Cardiovasc Surg. 2002;123:570–571[Free Full Text]
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- Hoksbergen AWJ, Legemate DA, Ubbink DT, Jacobs MJHM. Collateral variations in circle of Willis in atherosclerotic population assessed by means of transcranial color-coded duplex ultrasonography. Stroke. 2000;31:1656–1660[Abstract/Free Full Text]
- Urbanski PP. Cannulation of the left common carotid artery for proximal aortic repair. J Thorac Cardiovasc Surg 2003;126:887–8
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Abstract
Introduction
