Dominant Left Vertebral Artery Research Articles

Gore TAG thoracic branch endograft for treatment of a subacute type B aortic dissection complicated by rupture

An 80-year-old man presented with a subacute zone 3-5 type B aortic dissection complicated by rupture and visceral and lower extremity malperfusion. He underwent emergent zone 2 repair with a Gore TAG thoracic branch endograft with inclusion of the left subclavian artery for a dominant left vertebral artery. The patient's postoperative course was uncomplicated. Type B aortic dissections can be anatomically complex, and rupture is a rare complication in the subacute phase. We report the novel use of a Gore TAG thoracic branch endograft for the management of type B aortic dissection complicated by rupture and demonstrate its feasibility for patients with type B aortic dissection complicated by rupture.

Abstract Number: LBA13 Relationship Between Vertebral Artery Dominance And Incidence Of Embolic Basilar Artery Occlusion

Introduction Vertebral artery asymmetry due to hypoplasia or early termination is common in the general population with 50% left dominance, 25% right dominance, and 25% codominance. Our aim was to identify if an association exists between vertebral artery dominance and incidence of embolic basilar artery occlusion. Methods Retrospective chart review of patients presenting to our comprehensive stroke center with acute ischemic stroke (AIS) secondary to embolic basilar artery occlusion were reviewed. Artery‐to‐artery occlusions related to athersclerotic steno‐occlusive disease or proximal dissection with distal thromboembolism were excluded. Successful recanalization was identified as a modified treatment in cerebral infarction (mTICI) score of 2b and 3. Fisher exact test statistic was used to assess for significant differences in recanalization. Social science statistics software was used for data analysis. Results From May 2017 to November 2019, 29 patients with acute basilar occlusions undergoing thrombectomy were identified. Acute basilar artery occlusion patients had a dominant right vertebral artery (31%, n = 9), codominant vertebral arteries (31%, n = 9) and dominant left vertebral artery (38%, n = 11). Successful recanalization of TICI 2b or higher was achieved in 89.6% (n = 26). Difference between successful recanalization and right or left vertebral artery dominance was not statistically significant (Fisher exact test statistic value 0.48). Conclusions Our study suggests a higher proportion of our patients presenting with basilar artery occlusion had right vertebral artery dominance or codominant pattern. Larger, studies are needed to validate our results.

Giant dissecting aneurysm of basilar artery in a child - treated by flow reversal: A case report.

Although intracranial aneurysms are rare in the paediatric population, the proportion of those involving posterior circulation is higher than that of adults (approximately 25% vs. 8%, respectively). Moreover, posterior circulation aneurysms in kids tend to be larger in size, many of them being giant dissecting types, and treatment of them is often challenging. Treatment of giant dissecting aneurysms, especially involving the Basilar artery is difficult due to strategic location and haemodynamic factors. Use of reconstructive techniques viz. flow-diverters and braided stents is difficult in children because of the lack of standard protocol for use of antiplatelet therapy and the need for prolonged use of the same. Continuous growth of parent vessel is also suggested as a pitfall for the use of a flow diverter/ braided stent which has a fixed caliber. Carefully planned endovascular parent or feeder branch artery occlusion (FAO) is a time-tested method to achieve flow reversal or favourable flow modifications in an arterial segment harbouring dissecting aneurysm. Here, in this case report, we describe a case of a ruptured distal giant basilar artery dissecting aneurysm in a 10-year-old boy treated with flow diversion by FAO. The dominant left vertebral artery was occluded, thereby diverting flow from the right vertebral artery towards the left posterior inferior cerebellar artery and decreasing flow through the aneurysm. On 1-year follow-up, the patient was asymptomatic and on check angiography, there was complete involution of the aneurysm with increased flow through bilateral posterior communicating arteries to distal posterior circulation which proved our hypothesis correct.

Clinical case of Bow Hunter's Syndrome

Bow Hunter‘s Syndrome (BHS) is a mechanical compression of the vertebral artery during head rotation, leading to partial disruption or complete interruption of the blood flow of the affected artery, causing vertebrobasilar vascular insufficiency. There are no established precise diagnostic and therapeutic behavioral algorithms in patients with BHS. I present a case of an 80-year-old woman with syncopal symptoms, in which a dynamic stenosis of the dominant left vertebral artery was diagnosed, and the same artery originates from the aortic arch with a separate ostium.

Modified Sternocleidomastoid Sparing Approach for Vertebral Artery (V1) to Common Carotid Artery Transposition: 2-Dimensional Operative Video.

Vertebral artery (VA) V1 segment to common carotid artery (CCA) transposition is an uncommon operation with existing literature describing dissection of the sternoclavicular head of the sternocleidomastoid (SCM) muscle.1,2 We present a modified approach for transposition without cutting the SCM. Our patient is a 76-yr-old female with history of a previous cerebellar stroke. Despite taking aspirin, she presented with another stroke resulting in severe dysarthria, vertigo, and gait disturbance. Magnetic resonance imaging (MRI) demonstrated several cerebellar infarcts. Catheter angiography demonstrated bilateral vertebral artery occlusion with filling from ascending cervical branches and a dominant left VA. We planned a left V1 to CCA transposition with a modified SCM-sparing approach for which the patient provided written informed consent. She was positioned supine with neck extended and face turned to the right. Neuromonitoring was utilized. A linear incision along the anterior border of the SCM was made, stopping 1.5 cm above the clavicular head. Neurovascular structures of the carotid sheath were dissected circumferentially and mobilized medially. The longus coli muscle over the C6 lateral mass was reflected medially. The vertebral artery was dissected to expose the maximum possible length. The inferior thyroid artery was sacrificed for better exposure. VA was ligated and transected. CCA was clamped. VA to CCA bypass was performed in a standard fashion. Surgical site was closed. The patient clinically did well postoperatively with immediate symptom improvement. Our video demonstrates an SCM-sparing technique of V1 to CCA transposition, which can be a less-extensive operation compared to the traditional approaches, which require transection of SCM head.

Optical Coherence Tomography of Plaque Erosion and Thrombus in Severe Vertebral Artery Stenosis.

A 69-year-old male presented with medically refractory vertebrobasilar insufficiency and paroxysmal subjective dizziness for six months. Severe stenosis of a dominant left V2 vertebral artery segment was identified on digital subtraction angiography (DSA) with an irregular intraluminal filling defect immediately above the stenosis. Optical coherence tomography (OCT) demonstrated a normal lumen at the distal end, with red thrombus detected distal to the stenosis. Atherosclerotic plaque containing fibro-lipid was also identified and treated with a drug-eluting stent. Distal red thrombi were not covered by stenting, indicating embolization risk in the future. Clear posterior fossa symptoms occurred after intervention, and treatment with a standard dual antiplatelet regimen and statin therapy was prescribed for one year. Six months after treatment, the symptoms improved, and six-minute walking distances were successful with no gait impairment. To our knowledge, this is the first V2 segment stenosis assessed by OCT imaging before and after stenting, indicating an intact fibrous cap with thrombus formation, as well as plaque erosion. Understanding the role and careful use of OCT may improve the identification of red thrombus and plaque erosion when clinically indicated.

Endovascular treatment of a saccular aneurysm associated with fenestrated basilar artery and proximal stenosis of vertebral artery origin - A treatment challenge

A 52-year-old woman had subarachnoid haemorrhage due to an aneurysm at a fenestration of the vertebrobasilar artery junction. The fenestration and aneurysm filled by the dominant left vertebral artery (VA). The left VA had a tight stenosis at its origin from the left subclavian artery. The patient underwent a stent-assisted coiling of the aneurysm after balloon dilatation of the proximal stenosis. The management of this unusual and rare entity is discussed. The relevant literature on the subject is presented.

Left Subclavian Artery Revascularization for Thoracic Aortic Stentgrafting: Single Center Experience in 101 Patients

Introduction - Endovascular treatment of thoracic aortic pathology (TEVAR) requires a landing zone of at least 20mm in length, necessitating coverage of the left subclavian artery (LSA) in approximately 40% of the patients.1 Coverage of the LSA may increase the risk of ischaemic stroke, spinal cord ischaemia (SCI) and/or left arm claudication. Besides some endovascular options to preserve LSA flow, in the majority of cases the LSA is surgically revascularized by either a carotid-to-subclavian bypass graft or subclavian-carotid transposition. A relatively safe option, which has been shown to decrease the risk of stroke compared to LSA coverage without revascularization.2,3 Conflicting data and opinions exist in literature on the (additional) risk of surgical LSA revascularization (requiring temporary occlusion of the left common carotid artery (LCCA) for the anastomosis).4,5,6 In this study, we retrospectively analysed the indications, as well as the operative results of LSA revascularization in 97 patients, in our single centre TEVAR experience. Methods - Between 2000 and 2017, a total of 101 consecutive patients underwent surgical revascularization of the LSA prior to, concomitant, or following TEVAR. Data were retrospective collected. Revascularization was performed through a small supraclavicular incision and consisted of a transposition or bypass graft, using perioperative transcranial Doppler. Data regarding the indication for LSA revascularization, procedural details and early and late postoperative results were analysed. Results - A total of 64 carotid-subclavian bypass grafts and 33 subclavian-carotid transpositions were performed in the context of TEVAR. The majority was performed prior to stentgrafting, indicated to reduce the risk of stroke (n=58, incomplete Willis’ circle, dominant left vertebral artery (LVA) and/or exclusion of an arteria lusoria), to reduce the risk of SCI (n=18, in case of previous aortic repair, and/or stenting the entire descending aorta) or to reduce the risk of left arm malperfusion (n=8, small or absent LVA or LVA originating from the aortic arch). In two patients there was a patent left internal mammary artery to coronary artery bypass graft. In fourteen patients LSA revascularization was performed secondary to the stentgraft procedure, either immediately due to acute left arm malperfusion (n=2) or during follow-up due to invalidating left arm claudication (n=12). There was no in-hospital mortality, two ischaemic strokes (2%) were noted and one patient experienced permanent SCI (1%). Both strokes were considered to be related to the stentgraft procedure rather than the preceding LSA bypass. Additional complications observed were sympathetic chain nerve palsy (Horner’s syndrome) (n=6), phrenic nerve palsy (n=5), recurrent nerve palsy (n=4), chyle leakage requiring diet or re-exploration (n=6). In one patient, the LSA bypass occluded during follow-up requiring a redo surgical bypass. Conclusion - Selective surgical revascularization of the left subclavian artery in case of LSA coverage in TEVAR may be indicated to lower the risk of stroke, spinal cord ischaemia, and left arm malperfusion. The procedure can be performed safely when using perioperative monitoring and result in a low risk of stroke and peripheral nerve injury. References1)Kotelis D, Geisbüsch P, Hinz U, Hyhlik-Dürr A, von Tengg-Kobligk H, Allenberg JR, Böckler D. Short and midterm results after left subclavian artery coverage during endovascular repair of the thoracic aorta. J Vasc Surg. 2009 Dec;50(6):1285-1292.2)Patterson BO, Holt PJ, Nienaber C, Fairman RM, Heijmen RH, Thompson MM. Management of the left subclavian artery and neurologic complications after thoracic endovascular aortic repair. J Vasc Surg 2014;60:1491-1497.3)Saouti N, Hindori V, Morshuis WJ, et al. Left subclavian artery revascularization as part of thoracic stent grafting. Eur J Cardiothorac Surg. 2015 Jan;47(1):120-125; discussion 125.4)Maldonado TS, Dexter D, Rockman CB, Veith FJ, Garg K, Arko F, Bertoni H, Ellozy S, Jordan W, Woo E. Left subclavian artery coverage during thoracic endovascular aortic aneurysm repair does not mandate revascularization. J Vasc Surg. 2013 Jan;57(1):116-124.5)Cooper DG, Walsh SR, Sadat U, Noorani A, Hayes PD, Boyle JR. Neurological complications after left subclavian artery coverage during thoracic endovascular aortic repair: a systematic review and meta-analysis. J Vasc Surg. 2009 Jun;49(6):1594-1601.6)Contrella BN, Sabri SS, Tracci MC, Stone JR, Kern JA, Upchurch GR, Matsumoto AH, Angle JF. Outcomes of Coverage of the Left Subclavian Artery during Endovascular Repair of the Thoracic Aorta. J Vasc Interv Radiol. 2015 Nov;26(11):1609-1614.

TAA11. Pushing the Limits of Proximal Sealing Zone for Emergency Thoracic Endovascular Aortic Repair by Periprocedural Combined Embolization for Acute Thoracic Aortic Aneurysm Rupture: In the Middle of the Night

Inadequacy of a proximal landing zone (zone 3 or 4) is often a limitation for thoracic endovascular aortic repair (TEVAR), particularly in acute situations. We present a completely new technique of tackling this issue during emergency TEVAR for a ruptured aneurysm of the descending thoracic aorta encroaching on the lesser curvature of the arch. A 66-year-old man was admitted with acute thoracic back pain. Contrast-enhanced computed tomography revealed contained rupture from aneurysm and type B dissection just caudal to the left subclavian artery. Proximal landing at zone 2 was inadequate. TEVAR with debranching and revascularization of neck arteries was an option but was ruled out because of the patient's comorbidities. Branched TEVAR was not an option because of latency in device delivery. Chimney technique was not used because of risk of type IA endoleak. After a left carotid-subclavian bypass (because of dominant left vertebral artery), we deployed a Zenith Alpha thoracic stent graft (ZTA-PT-40-36-217; Cook Medical, Bloomington, Ind) covering the left subclavian artery. However, because of inadequate proximal landing area inferiorly, the inferior margin of the stent graft opened in the aneurysm sac, giving rise to a type IA endoleak (Fig 1). We entered the aneurysm sac through the left subclavian artery and deployed a few Azur detachable macrocoils (Terumo Interventional Systems, Somerset, NJ) for clot formation and stabilization (Fig 2). We then embolized the rest of the aneurysm all the way up to the stent graft margin and also the proximal subclavian artery with Onyx (ev3, Covidien, Plymouth, Minn).Fig 2Aneurysm sac and proximal left subclavian artery are adequately embolized with detachable macrocoils and Onyx.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Computed tomography angiography 1 day after TEVAR showed complete exclusion of the aneurysm without any sign of endoleak as well as a stable and well-functioning stent graft. The patient is doing well 3 months after the procedure. To our knowledge, no similar case of concomitant embolization of aneurysm sac with TEVAR by combined coils and Onyx through the subclavian artery has been described in the literature. This technique was safe and can be used as an alternative, particularly in an emergency situation. However, long-term outcome of the technique is still awaited.

Stent-assisted coiling of a ruptured vertebrobasilar junction aneurysm via direct vertebral artery puncture

A 78-year-old patient was admitted with subarachnoid hemorrhage caused by rupture of a broad-based vertebrobasilar junction aneurysm. Direct endovascular access to the vertebrobasilar circulation was not possible due to chronic...

Minimally invasive surgery to the aortic arch – endovascular repair combined with debranching: 4 case reports

Traditional repair of aortic arch aneurysms requires cardiopulmonary bypass and a period of profound hypothermia and circulatory arrest - allowing detachment of the head vessels off the aneurysm, and their anastomosis onto the graft. The procedure is safe and reproducible, however morbidity is significant and includes air embolism, stroke, excessive bleeding and acidosis. In addition the procedures are time-consuming, and cardioplegic arrest is also necessary, resulting in the potential for low cardiac output. Aortic arch aneurysms are not typically suitable for endovascular intervention. With improving techniques of descending aortic repair with stent grafts, hybrid techniques, which involve aortic arch debranching - thereby creating a proximal landing zone of adequate length, followed by stenting over the aortic arch are becoming popular. Methods: Four cases are presented. The technique involves initial sternotomy or upper sternal split, detachment of the innominate and left common carotid arteries, and their reattachment to the ascending aorta by separate grafts (debranching procedure). During this time a side clamp is placed on the ascending aorta. The left subclavian is usually left intact for technical reasons, unless there is a dominant left vertebral artery. This is safe as the shoulder has adequate collateral circulation, and stenting over this vessel is therefore well tolerated. The aortic arch is then completely covered with a stent graft which is inserted via the femoral artery. Arteriography was performed at the end of the procedure to confirm stent graft position and exclusion of the lesion. Results: All surgical transpositions were successful, and the patients recovered without neurologic, bleeding or cardiac complications. Surgical conversion for aortic graft was never required. There were no endoleaks. Mean duration of follow up was 53.5 months (range 21-77). Conclusions: Endovascular repair of the descending thoracic aorta, initially reserved for inoperable patients, is now becoming the accepted initial management. With improved technology and endografts it is now the safest option, especially for traumatic dissection. These techniques have now extended to the aortic arch. Debranching of the aortic arch enables endovascular grafting in this area, thereby avoiding cardiopulmonary bypass and circulatory arrest. Good pre-operative planning is necessary to make the procedure feasible.

Left subclavian artery revascularization as part of thoracic stent grafting†

Intentional covering of the left subclavian artery (LSA) as part of thoracic endovascular aortic repair (TEVAR) can cause (posterior) strokes or left arm malperfusion. LSA revascularization can be done as prophylaxis against, or as treatment of, these complications. We report our experience with the surgical technique, indications and the results of LSA revascularization. Between 2000 and 2013, 51 patients of 444 patients who were treated by TEVAR, had LSA revascularization. All elective patients had a preoperative work-up with magnetic resonance angiography to evaluate the circle of Willis. In all, surgical access was through a left supraclavicular incision only. The majority (90%) had prophylactic LSA revascularization because of incomplete circle of Willis and or dominant left vertebral artery (LVA) (n=29), patent left internal mammary artery (n=1), prevention spinal cord ischaemia (SCI) (n=2), prevention left arm ischaemia due to small LVA (n=2) and LVA origin in arch (n=1). Fourteen percent had secondary revascularization, either immediate because of malperfusion of the left arm (n=2) or late after TEVAR because of persisting left arm claudication (n=5). In 12 patients, the following early complications were observed: re-exploration for bleeding, n=1; left recurrent nerve paralysis, n=2; left phrenic nerve paralysis, n=1; left sympathetic chain neuropraxia, resulting in Horner's syndrome, n=3; Chyle duct lesions, resulting in persistent Chyle leakage, n=3. Neither strokes nor SCI was observed. One patient experienced occlusion of the bypass at 6 months. The present study shows that the procedure of LSA revascularization as part of TEVAR is safe with low morbidity consisting of mainly (transient) nerve palsy.

Hybrid Treatment of a Complex Aortic Arch Aneurysm with an Aberrant Left Vertebral Artery

We report a case of an elderly male with significant comorbidities and a dominant aberrant left vertebral artery originating on an aneurysmal aortic arch. The patient underwent a successful staged hybrid procedure with aortic arch debranching and left vertebral artery transposition onto the left common carotid artery, followed by endovascular aneurysmal repair.

Results With a Selective Revascularization Strategy for Left Subclavian Artery Coverage During Thoracic Endovascular Aortic Repair

The need for routine left subclavian artery (LSCA) revascularization when this vessel is covered during thoracic endovascular aortic repair remains controversial. We report our results with a selective LSCA revascularization strategy during thoracic endovascular aortic repair. Between May 2002 and March 2010, 287 thoracic endovascular aortic repair procedures were performed at our institution. LSCA coverage occurred in 145 (51%), which form the basis of this report. Left subclavian artery revascularization was performed in 32 patients (22%) through a left common carotid-LSCA bypass. Indications for selective LSCA revascularization included spinal cord protection in 10, patent pedicled left internal mammary artery graft in 9, left arm ischemia after LSCA coverage in 5, origin of the left vertebral artery from the arch in 4, dialysis access in the left arm in 2, and vertebrobasilar insufficiency in 2. There were no instances of dominant left vertebral artery. The revascularized and non-revascularized groups had similar rates of death (6.3% vs 1.8%; p=0.21), stroke (3.1% vs 3.5%; p>0.99), permanent paraplegia or paraparesis (3.1% vs 0%; p=0.22), and type II endoleak (4.3% vs 6.5%; p>0.99). There were no instances of ischemic stroke related to left posterior circulation hypoperfusion. Four complications of carotid-subclavian bypass occurred in 3 patients (9.4%). Selective LSCA revascularization is safe and does not appear to increase the risk of neurologic events. Further, subclavian revascularization is not without complications, which should be considered with regards to a nonselective revascularization strategy.

Management of Blunt Traumatic Thoracic Aorta Injuries With Endovascular Stent-Grafts in a Tertiary Hospital in an Urban Asian City

Thoracic aortic injury from blunt trauma is a life-threatening condition with significant mortality and morbidity with open surgical repair. Endovascular means of treatment is emerging as an attractive and less invasive option. We report our experience with endovascular stent-graft repair for blunt traumatic thoracic aorta injury. Between January 2003 and August 2009, six patients underwent endovascular repair of blunt traumatic thoracic aorta injury. Data from the medical records of these patients were analyzed. All patients had deceleration injury resulting in thoracic aorta pseudoaneurysm at the aortic isthmus just distal to the left subclavian artery. Four patients were motorcyclists who had been involved in road-traffic accidents and two had fallen from a height. The mean Injury Severity Score was 33.8 (range, 21-43). All procedures were performed within 48 hours of admission and technical success was 100%. Five patients (83.3%) had the left subclavian artery intentionally covered by the stent-graft to achieve adequate proximal landing zone. None of them had any left upper limb ischemic complications or cerebrovascular events after the procedure. One patient had preservation of the left subclavian artery because intraoperative vertebral angiogram showed a hypoplastic right vertebral artery. No other procedural complications, paraplegia, or deaths were reported. Mean follow-up was 18.8 months (range, 1.5-42 months). Our early experience of endovascular stent-grafting for blunt traumatic thoracic aorta injury suggests that this emerging technique is safe for treatment of such pathology in our inherently Asian population. Left subclavian artery may be sacrificed if adequate proximal landing zone is required for the stent-graft; and when vertebral angiogram was performed which did not show a dominant left vertebral artery.

Cervical Vertebral Artery Rerouting

The endovascular treatment of intracranial aneurysms can be hampered by the tortuosity of extracranial vessels. Percutaneous or surgical vessel puncture can resolve the problem of inaccessibility. We describe rerouting of a kinked vertebral artery (VA) to restore transfemoral endovascular access to an aneurysm. A 63-year-old woman presented with progressive hemiparesis. Magnetic resonance imaging demonstrated a left fusiform vertebrobasilar aneurysm with mass effect on the brainstem. The patient was found to have a dominant left VA on angiography with a severe kink in its V1 segment. Tight loops of this segment prevented catheter progression past V1 during endovascular treatment. The left VA was rerouted from its subclavian origin to the C5 transverse foramen through a combined lateral and supraclavicular approach. Release of the VA off the C6 transverse process and C6 and C7 cranial nerve roots permitted unfolding of the VA. The excess length of the VA, initially present between the subclavian artery and the C6 transverse process, was spread over a longer distance. The tight angles present preoperatively were converted into a harmonious curvature. The rerouted VA was attached to surrounding soft tissue to maintain its position. The patient's postoperative course was uneventful. Endovascular treatment of the aneurysm was performed 15 days later. The VA rerouting technique can be used successfully in patients in whom tight loops in the VA prevent endovascular access to intracranial vessels.

Management of the Left Subclavian Artery During Endovascular Repair of the Thoracic Aorta

Endovascular repair is rapidly becoming the treatment of choice for thoracic aortic disease, which oftentimes involves or lies in close proximity to the left subclavian artery (LSA). In order to extend the proximal landing zone for the stent-graft and obtain an adequate seal, the LSA ostium is often covered, with or without concomitant subclavian artery revascularization. In this article, we review the LSA anatomy and consequences of LSA coverage as a backdrop for a discussion of the ramifications of LSA coverage during endovascular thoracic aortic repair (TEVAR). Early series reported high rates of LSA revascularization as an adjunct to endovascular repair for aortic pathology adjacent to the LSA ostium. Initial reports of low morbidity associated with simple LSA ostium coverage are not supported by contemporary literature, which suggests revascularization reduces the risks of cerebrovascular accident and spinal cord ischemia. Coverage of the LSA without revascularization may be justified only in emergency situations or when thorough investigations of cerebral and vertebrobasilar circulation have concluded that the risk to brain and spinal cord is low. Subclavian revascularization should be considered in the presence of a dominant left vertebral artery, bilateral carotid artery disease, an occluded/stenosed right vertebral artery, presence of a left internal mammary artery graft, or when a long length of thoracic aorta is covered.

Rotational vertebral artery syndrome

Whether the rotational vertebral artery syndrome (RVAS), consisting of attacks of vertigo, nystagmus and tinnitus elicited by head-rotation induced compression of the dominant vertebral artery (VA), reflects ischemic dysfunction of uni- or bilateral peripheral or central vestibular structures, is still debated. We report on a patient with bilateral high-grade carotid stenoses, in whom rightward headrotation led to RVAS symptoms including a prominent nystagmus. Three-dimensional kinematic analysis of the nystagmus pattern, recorded with search coils, revealed major downbeat nystagmus with minor horizontal and torsional components. Magnetic resonance angiography demonstrated a hypoplastic right VA terminating in the posterior inferior cerebellar artery, a dominant left VA, and a hypoplastic P1-segment of the left posterior cerebral artery (PCA) that was supplied by the left posterior communicating artery (PCoA). The right PCA and both anterior inferior cerebellar arteries were supplied by the basilar artery. The right PCoA originated from the right internal carotid artery. Color duplex sonography showed severe reduction of diastolic blood flow velocities in the left VA during RVAS attacks. The nystagmus pattern can be best explained by vectorial addition of 3D sensitivity vectors of stimulated right and left anterior and horizontal semicircular canals with slightly stronger stimulation on the left side. We hypothesize that in RVAS, compression of dominant VA leads to acute vertebrobasilar insufficiency with bilateral, but asymmetric ischemia of the superior labyrinth. With regard to RVAS etiology, our case illustrates a type of pure vascular RVAS. Severity of attacks markedly decreased after successful bilateral carotid endarterectomy.

Risk Factors for Perioperative Stroke during Thoracic Endovascular Aortic Repairs (TEVAR)

To determine the clinical and anatomical risk factors for cerebrovascular accidents (CVA) in patients undergoing thoracic endovascular aortic repair (TEVAR). Between September 2000 and December 2006, 196 patients (135 men; mean age 68.6+/-13.5 years, range 17-92) underwent TEVAR for a variety of aortic pathologies. The majority (156, 79.6%) were treated with the TAG stent-graft. Demographics, pathologies, intraoperative procedure-related measures, device usage, and postoperative outcomes were assessed. CVA was defined as a new focal or global neurological (motor or sensory) deficit lasting >48 hours associated with acute intracranial abnormalities on computed tomography or magnetic resonance brain imaging. Spinal cord ischemia was excluded. In a subset of patients with planned left subclavian artery (LSA) coverage and an incomplete circle of Willis or a dominant left vertebral artery, prophylactic carotid-subclavian bypasses were performed. Nine (4.6%) patients suffered a CVA. Factors not predictive of a CVA on univariate analysis included aortic pathology, urgency of repair, ASA classification, type of anesthesia, blood loss, procedure time, and device used. Proximal extent of repair (with or without extra-anatomical revascularization) was significantly associated with a higher incidence of strokes (zones 0-2 versus 3-4, p=0.025). Five (55.6%) patients with a CVA had documented intraoperative hypotension (systolic blood pressure<80 mmHg). Additionally, while 2 patients had hemispheric infarcts, 5 had acute posterior circulation infarcts involving the cerebellum and brainstem; a single patient had both anterior and posterior circulation infarcts. Seven of the CVA patients had proximal coverage of the thoracic aorta in zones 0-2; of these, 6 had posterior circulation infarcts. Selective LSA revascularization based on preoperative cerebrovascular imaging resulted in lower rates of CVA (6.4% to 2.3%, p=0.30) and posterior circulation infarcts (5.5% to 1.2%, p=0.13). Proximal extent of repair may serve as a surrogate marker for greater severity of degenerative disease of the aortic arch. Avoidance of intraoperative hypotension and preservation of antegrade vertebral perfusion may be important in prevention of posterior circulation strokes.

Intraoperative dynamic angiography to detect resolution of Bow Hunter's syndrome: technical case report

Background Bow Hunter's syndrome is a rare form of vertebrobasilar insufficiency that may be successfully treated by surgical intervention. Use of intraoperative dynamic transcranial Doppler ultrasound for surgical treatment of vertebrobasilar insufficiency has been described in literature. However, this technique was inconsistent and unreliable in some patients. We present a case of a patient with Bow Hunter's syndrome treated surgically and emphasize the valuable addition of intraoperative dynamic angiography to determine resolution of vertebral artery compromise. Case Description The patient was a 58-year-old man with complaints of dizziness, vertigo, and near-syncopal episodes that occurred when he rotated his head to the left. Imaging revealed compromise of the dominant left vertebral artery with leftward head rotation. An anterior cervical approach with decompression of the left subaxial vertebral artery was performed. Significant osteophyte formation was observed. Removal of bone and decompression of the vertebral artery was performed. Intraoperative dynamic angiography confirmed resolution of vertebral artery compression and minimized the amount of decompression. No further intervention was required. Conclusion Intraoperative dynamic angiography is a definitive test to determine hemodynamic resolution of Bow Hunter's syndrome. It offers real-time feedback of vertebral artery decompression, potentially minimizes the amount of decompression, and can be performed safely.