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Intrathoracic carotid bifurcation in Klippel-Feil syndrome

2008; Elsevier BV; Volume: 47; Issue: 5 Linguagem: Inglês

10.1016/j.jvs.2007.11.022

1097-6809

James P. Rielly,

Esophageal and GI Pathology

Intrathoracic carotid bifurcation is rare with only five other cases reported. This anatomic variant with posteromedial origin of the internal carotid artery (ICA) appears to be part of the Klippel-Feil syndrome, a rare congenital defect characterized by fusion of the cervical vertebrae. Caution is advised when planning thoracic and cervical vascular procedures. Angiography carries higher risk of unintentional ICA catheterization due to the short common carotid artery length. The intrathoracic location of the carotid bifurcation makes endarterectomy difficult and patients may do better with carotid artery stenting. Ultrasound can be confusing in these patients and MRA may be preferable. Intrathoracic carotid bifurcation is rare with only five other cases reported. This anatomic variant with posteromedial origin of the internal carotid artery (ICA) appears to be part of the Klippel-Feil syndrome, a rare congenital defect characterized by fusion of the cervical vertebrae. Caution is advised when planning thoracic and cervical vascular procedures. Angiography carries higher risk of unintentional ICA catheterization due to the short common carotid artery length. The intrathoracic location of the carotid bifurcation makes endarterectomy difficult and patients may do better with carotid artery stenting. Ultrasound can be confusing in these patients and MRA may be preferable. The carotid bifurcation is fairly constant at the C3-C5 level, although cervical variation is well reported.1Anu V.R. Pai M.M. Rajalakshmi R. Latha V.P. Rajanigandha V. D'Costa S. Clinically-relevant variations of the carotid arterial system.Singapore Med J. 2007; 48: 566-569PubMed Google Scholar, 3Vitek J.J. Reaves P. Thoracic bifurcation of the common carotid artery.Neuradiology. 1973; 5: 133-139Crossref PubMed Scopus (23) Google Scholar Intrathoracic bifurcation, however, is a rare entity with only five cases found in a recent review of the angiographic literature.2Gailloud P. Murphy K.J. Rigamonti D. Bilateral thoracic bifurcation of the common carotid artery associated with Klippel-Feil anomaly.Am J Neuroradiol. 2000; 21: 941-944PubMed Google Scholar, 3Vitek J.J. Reaves P. Thoracic bifurcation of the common carotid artery.Neuradiology. 1973; 5: 133-139Crossref PubMed Scopus (23) Google Scholar, 4Brill C.B. Peyster R.G. Keller M.S. Galtman L. Isolation of the right subclavian artery with subclavian steal in a child with Klippel-Feil anomaly: an example of the subclavian artery supply disruption sequence.Am J Med Genet. 1987; 2: 933-940Crossref Scopus (38) Google Scholar This anatomic variant appears to be part of the Klippel-Feil syndrome, an uncommon congenital disorder characterized by fusion of the cervical vertebrae. A 42-year-old normotensive, nondiabetic, smoking white female presented with complaints of right arm claudication and right-sided amaurosis fugax. She was diagnosed in childhood with Klippel-Feil syndrome, a rare congenital disorder characterized by fusion of the cervical vertebrae. Associated abnormalities included a short, webbed neck with low hairline and congenital absence of the left kidney, ovary, and fallopian tube. Diagnostic ultrasound was technically difficult due to the patient's short, webbed neck (4 cm from mandibular angle to clavicle). Magnetic resonance angiogram (MRA) showed innominate artery occlusion and 40% left subclavian artery stenosis (Fig 1). A study done for cervical pain 2 years prior had shown the innominate artery to be 50% stenosed with antegrade flow. The left common carotid artery (CCA) was seen to bifurcate at the T3 level, with the internal carotid artery (ICA) posteromedial to the external carotid artery (ECA) (Fig 2). The right CCA bifurcated at a normal level, C5 of the fused C5-C7 vertebral complex, with the ECA in the normal medial position. Angiography confirmed the MRA findings and innominate artery occlusion. Attempts at antegrade catheterization of the innominate artery for angioplasty/stenting were unsuccessful.Fig 2Intrathoracic bifurcation of the left common carotid artery with posteromedial orientation of the internal carotid artery (thin arrow).View Large Image Figure ViewerDownload Hi-res image Download (PPT) Under general anesthesia, the right CCA was exposed through an anterior sternocleidomastoid incision and retrograde crossing of the innominate artery was unsuccessfully attempted. Retrograde angiography again confirmed occlusion. With Sundt shunts in place, the left ICA was exposed and a left ICA- right CCA bypass was performed with 7-mm externally supported polytetrafluoroethylene graft. The left ECA branched very low, and only branches were seen in the dissection. These were felt to be too small to use for bypass inflow. Postoperative recovery was uncomplicated. Postoperative brachial pressures were 118/78 left and 99/67 right with palpable radial pulses bilaterally and ultrasound confirmed satisfactory antegrade flow in both distal ICAs and retrograde right CCA flow. Klippel-Feil syndrome is a rare disorder characterized by the congenital fusion of at least two cervical vertebrae. Since description by Maurice Klippel and Andre Feil in 1912 with the clinical triad of a short, webbed neck, low posterior hairline, and decreased neck mobility, multiple associated anomalies have been reported including congenital scoliosis (60%), scapular deformity (33%), hearing loss (30%), syndactyly, hypoplastic thumb, renal aplasia, cleft palate, synkinesis, cervical stenosis, spina bifida, and brain stem, cardiac, and genitourinary abnormalities.4Brill C.B. Peyster R.G. Keller M.S. Galtman L. Isolation of the right subclavian artery with subclavian steal in a child with Klippel-Feil anomaly: an example of the subclavian artery supply disruption sequence.Am J Med Genet. 1987; 2: 933-940Crossref Scopus (38) Google Scholar, 5Sullivan AJ. Klippel-Feil syndrome. In: Emedicine from WebMD, revised Mar 9, 2007 at http://www.emedicine.com/orthoped/topic408.htmGoogle Scholar, 6National Institute of Neurological Disorders and Stroke (NINDS) Klippel-Feil Syndrome Information Page, revised Feb 13, 2007 at http://www.ninds.nih.gov/disorders/klippel_feil/klippel_feil.htmGoogle Scholar Associated carotid anomalies have been noted with low cervical and intrathoracic carotid bifurcation.A second patient with posteromedial take-off of the ICAs relative to the ECA, an uncommon variant, was previously reported.In this patient, the relative positions of the ICA and ECA on the right were normal; the left side branched very low and the ECA proper was not seen in the cervical dissection, only branches which appeared to be in their expected positions. Klippel-Feil syndrome occurs due to failure of normal segmentation of cervical somites during the third and eight weeks of gestation. This may be due to disruption of the embryonic blood supply in the subclavian artery around the sixth week of development, termed subclavian artery supply disruption sequence. This is thought to be responsible for a group of birth defects including Klippel-Feil, Poland syndrome (underdevelopment or absence of the pectoralis muscles), and Mobius syndrome of congenital facial diplegia caused by the absence or underdevelopment of the sixth and seventh cranial nerves.7Bavinck J.N. Weaver D.D. Subclavian artery supply disruption sequence: hypothesis of a vascular etiology for Poland, Klippel-Feil, and Mobius anomalies.Am J Med Genet. 1986; 23: 903-918Crossref PubMed Scopus (426) Google Scholar, 8Issaivanan M. Virdi V.S. Parmar V.R. Subclavian artery supply disruption sequence – Klippel-Feil and Mobius anomalies.Indian J Pediatr. 2002; 69: 441-442Crossref PubMed Scopus (19) Google Scholar Knowledge of this association is important when evaluating the arch and great vessels. Ultrasound is confusing in these patients, and MRA appears to be the preferred imaging technique. Care must be taken to include the aortic arch and its branches when evaluating the cervical vasculature of these patients. When indicated, angiography carries a higher risk of unintentional ICA catheterization due to the very short CCA length. Further, the intrathoracic location of the carotid bifurcation makes endarterectomy difficult, and these patients may do better with carotid artery stenting. In this patient, the carotid bifurcations were without significant disease. The amaurosis was presumably atheroembolic secondary the innominate lesion before it occluded: antegrade and retrograde angiograms both showed innominate occlusion and postoperative ultrasound confirmed retrograde right carotid flow so the risk of recurrent atheroembolism seems quite low. The etiology of this lesion remains unproven. Radiographic (including subclavian stenosis) and clinical findings (amaurosis fugax, smoking) suggest atherosclerotic disease, despite her young age. A review of the published literature concerning Klippel-Feil syndrome describes neither advanced nor premature atherosclerosis. There does appear to be an association with aortic coarctation but such rapid progression of a congenital vascular stenosis seems unlikely. Thoracic outlet syndrome is also associated with the Klippel-Feil syndrome but would not affect the innominate artery. In terms of repair, several options were presented. Direct repair with innominate endarterectomy or bypass was offered but refused. This patient has markedly decreased upper body range of motion and had poor outcomes for surgery to correct cervical spinal stenosis and scapular malformation (Sprengel's deformity) and was very worried that sternotomy could lead to worsening of her debilitating thoracic back, shoulder, and neck problems. She preferred an endovascular approach or extra-anatomic bypass. Thinking the occlusion to be recent, antegrade crossing with a distal embolic protection device was attempted but unsuccessful. A retrograde open approach with cerebral protection by distal CCA clamping and flushing of antegrade flow was considered but, again, the lesion could not be successfully crossed. Extra-anatomic flow with inflow from the contralateral system successfully restored flow to the right brachiocephalic system. Klippel-Feil syndrome is associated with intrathoracic CCA bifurcation and posteromedial origin of the ICA. Caution is advised when planning thoracic and cervical vascular procedures. Angiography may carry higher risk of unintentional ICA catheterization due to the short CCA length, underscoring the routine use of arch angiography prior to branch cannulation. Ultrasound will not visualize the bifurcation and so may be inappropriate as a diagnostic tool in these patients. Further evaluation with MRA, CTA, or angiography may be needed to better explain this uncommon anatomy.