Neurol India Home 
 

ORIGINAL ARTICLE
Year : 2022  |  Volume : 70  |  Issue : 2  |  Page : 638--642

Stroke and the Bovine Aortic Arch: Incidental or Deliberate? A Comparative Study and our Experience

Swapnil Samadhiya, Dilip Maheshwari, Vijay Sardana, Bharat Bhushan 
 Department of Neurology, Government Medical College, Kota, Rajasthan, India

Correspondence Address:
Dr. Swapnil Samadhiya
R. No. 45, Pg3 Hostel, MBS Hospital, Kota, Rajasthan
India

Abstract

Aim and Objectives: We aimed to find the prevalence of bovine aortic arch in stroke and non-stroke patients and to study the relationship between bovine aortic arch and the occurrence of stroke. Materials and Methods: One hundred patients with and without stroke underwent computed tomography (CT) angiography of the thoracic aorta and its arch. Fifty diffusion-weighted magnetic resonance imaging (MRI)-confirmed anterior circulation stroke patients who had undergone digital subtraction angiography (DSA) afterward formed the case group. As controls, another 50 patients who had thoracic CT angiograms for disease other than stroke during this time period were randomly selected. Demographics and prevalence of bovine arch were compared between cases and controls. In the case group, demographics and prevalence of bovine arch variants and their relationship to stroke were studied. Results: Prevalence of bovine aortic arch variant in anterior circulation stroke was 22%, compared to 6% in non-stroke patients (P = 0.043). The bovine aortic arch was associated with the younger onset of stroke occurrence (P = 0.046). In the bovine arch group, the proportion of left-sided strokes (P = 0.022) and bilateral strokes (P < 0.00001) was significantly higher. As compared to type A (P = 0.140), type B bovine aortic arch had a better association (P = 0.092). Conclusions: Bovine aortic arch is a risk factor for young-onset anterior circulation stroke. Bilateral and left-sided infarcts were more common. Endovascular procedures are difficult to perform through conventional routes, so brachioradial access is preferred.



How to cite this article:
Samadhiya S, Maheshwari D, Sardana V, Bhushan B. Stroke and the Bovine Aortic Arch: Incidental or Deliberate? A Comparative Study and our Experience.Neurol India 2022;70:638-642


How to cite this URL:
Samadhiya S, Maheshwari D, Sardana V, Bhushan B. Stroke and the Bovine Aortic Arch: Incidental or Deliberate? A Comparative Study and our Experience. Neurol India [serial online] 2022 [cited 2022 Aug 11 ];70:638-642
Available from: https://www.neurologyindia.com/text.asp?2022/70/2/638/344630


Full Text



The arch of the aorta is the part of aorta that lies between the ascending and descending aorta. It is an important structure from which the blood vessels supplying the head, neck, and upper thorax arise. Many variations in the branching pattern are known to exist.[1] The standard branching pattern, which is present in around two-thirds of the population, consists of three major branches. Right to left, they are the brachiocephalic trunk (BT), the left common carotid (LCC) artery, and the left subclavian (LS) artery. Right common carotid artery is a branch of right BT.[2] Among the different branching patterns [Table 1], the bovine aortic arch is also the most common variant of the aortic arch.[3],[4],[5],[6],[7],[8],[9] Its prevalence varies from 6% to 31% in various populations.[11],[12],[13],[14],[15],[16] Due to the varied geometry of the arch of aorta, there are altered flow patterns. In turn, this affects the motion of the clot and the propensity of a stroke. Gold et al.,[2] in 2018, suggested that in patients with standard arches, strokes tend to occur more frequently on the right side. Patients having bovine-type aortic arch have an almost equal chance of developing a right- or left-sided infarction. An abnormality in the arterial branching or arterial origin alters flow hemodynamics and damages the endothelium.[17] In 2013, Ribo et al.[18] demonstrated that the presence of bovine aortic arch can increase the duration of endovascular stroke management. In addition, endovascular procedures such as cannulation and placement of carotid artery stents were difficult.[19],[20] Hence, prior knowledge and planning may help overcome catheterization difficulties. With the growing interest in interventional neurology, it is crucial that interventional neurologists should have a thorough understanding of the anatomic variations of the aortic arch,[21],[22] which can help overcome technical difficulties when performing procedures. There are very few studies investigating the relationship between bovine aortic arch and stroke, and no studies from India. Therefore, we aimed to determine whether there is a connection between anterior circulation stroke and bovine aortic arch, in order to assess whether it is a risk factor. Furthermore, we intend to highlight the issues encountered while maneuvering through it and discuss how to overcome them.{Table 1}

 Materials and Methods



Patient Collection

Ethical clearance was obtained for this observational study from the GMC Kota Ethics Committee. The branching pattern of the aortic arch was evaluated in100 patients with (n = 50) and without (n = 50) strokes between March 2020 and September 2020. The cases consisted of 50 patients who were treated for acute anterior circulation stroke and had undergone computed tomography (CT) angiographic imaging of brain, neck vessels, and arch of aorta. This was followed by digital subtraction angiography (DSA) in our Department of Neurology. We only included anterior circulation stroke because the vertebrobasilar circulation was unlikely to be affected by bovine arch. The control group consisted of 50 randomly selected CT angiograms of the chest (arterial contrast phase, slice thickness 1–2 mm) from the same time period. The majority of scans were done for suspected pulmonary embolisms, cancer staging, and trauma. Poor contrast of the thoracic aorta or imaging artifacts, acute dissection, or aortic trauma patients of age less than 18 years were excluded. Thus, 50 stroke and 50 non-stroke patients were included. Patients were considered to suffer from an acute stroke if the clinical features correlated with diffusion-weighted magnetic resonance imaging (MRI) findings. As the perpendicular view of the aortic arch is required, evaluation was done using reconstruction of images taken in left oblique parasagittal planes. Bovine arch is considered when the common trunk is identified in both the axial plane as well as the oblique parasagittal plane.

Statistical Analysis

Microsoft Excel (2019; Microsoft, Washington, USA) and Statistical Package for the Social Sciences (SPSS) (version 25; IBM, New York, USA) were used for statistical analysis. Categorical variables are expressed as a number and percentage of patients and continuous variables as mean ± standard deviation. For categorical data like gender and branching patterns of the aortic arch, Pearson's χ2 test with a Yates' correction was used for the evaluation of statistical independence, followed by P value calculation. Continuous variables (age) were tested for normal distribution using the Shapiro–Wilk test. A P value < 0.05 was considered significant.

 Results



A study of 100 patients was conducted, of whom 50 had embolic strokes. The remaining 50 were non-stroke patients. Stroke patients had an average age of 54 ± 4.1 years, and 78% were males. Among non-stroke patients, the average age was 52.26 ± 4.1 years and 70% were male [Table 2]. In patients with the standard arch, the average age of stroke presentation was 56.66 ± 4.21 years [Table 3], and in patients with the bovine arch, it was 50.81 ± 10.5 years. Statistically, the difference was significant (P = 0.046). Bovine aortic arch variants were more common among patients suffering from anterior circulation stroke, with a prevalence of 22% in the stroke group compared to 6% in the non-stroke group. It was also statistically significant (P = 0.043) [Table 4]. A bovine arch type A was found in 12% of stroke patients (P = 0.140) and a bovine arch type B was found in 10% of stroke patients (P = 0.092). In non-stroke patients, type A was found in 4% and type B in 2% of patients [Table 4]. Patients with standard arches had strokes on the left in 53% of cases, on the right in 45% of cases, and bilaterally in 2% of cases. Left-side (36%, P = 0.249) and right-side (36%, P = 0.022) involvement was equally prevalent in the bovine arch group [Table 5]. Bilateral strokes were significantly higher in the bovine arch group (28%, P < 0.00001) [Table 5].{Table 2}{Table 3}{Table 4}{Table 5}

 Discussion



The arch of the aorta is the part of the aorta between the ascending and descending portions. As it passes from right to left, it gives rise to the brachiocephalic, LCC, and LS arteries. The brachiocephalic artery is the largest and ascends parallel to the ascending aorta. The LCC lines up perpendicularly to the arch of the aorta. Literature on the relationship between strokes and bovine aortic arch variants is limited. It was previously considered an incidental finding and not given any weight. According to Gold et al., the LCC lies perpendicular to the arch of the aorta, thus reducing the chances of emboli entering it. Consequently, the percentage of right-sided strokes in the standard arch is higher (59% vs. 38%). Further, they found that patients with bovine aortic arch had nearly the same prevalence of right-sided and left-sided anterior circulation stroke (49% vs. 51%). This can be explained by the fact that right and left common carotid arteries share a common origin, which results in equal risks of developing anterior circulation strokes on either side. In our study, we observed right-sided strokes in 36% of patients, left-sided strokes in 36% of patients, and bilateral strokes in 28% of patients. Left-sided infarcts (P = 0.022) and bilateral infarcts (P < 0.0001) were proportionately higher than the standard arch, and the difference was statistically significant. A study by Syperek et al.[1] reported no differences in gender or age between patients with standard aortic arch and bovine aortic arch. We found a significant association between the bovine aortic arch and the younger age of stroke occurrence (P = 0.046). The age of presentation for stroke in the standard arch group was 56.66 ± 4.21 years and in the bovine arch group was 50.81 ± 10.5 years. Syperek et al.[1] found a significant correlation (P = 0.039) between stroke and bovine aortic arch type B. The prevalence of bovine aortic arch in stroke patients was higher than in the general population (25.7% vs. 17.1%). Type B was the most prevalent among patients, accounting for 12.1% of them. The same correlation was found in our study as well. We found an overall significant correlation between bovine aortic arch and stroke (P = 0.043). Our study of 50 stroke patients found 22% (n = 11) had bovine aortic arches, 12% (n = 6) had type A, and 10% (n = 5) had type B [Table 5]. Moorehead et al. found that type B bovine aortic arch patients with aneurysms and dilated arches were more likely to suffer strokes.[23] Our study findings showed that both types A and B of bovine aortic arch contribute to embolic stroke risk. According to Casa L et al., an abnormally curved aortic arch can cause thrombi to form,[24] as in the case of the bovine aortic arch. On the hemodynamic evaluation of bovine aortic arches, Shalhub et al.[25] observed the altered flow patterns and more regional shear stress. This can cause endothelial damage.[26] In the same way, Malone et al. proposed that a fewer number of aortic arch branches may also contribute to this. In such cases, a higher flow velocity of blood may lead to vessel dissection or aneurysm formation.[27] There is a racial predisposition to aortic arch anomalies, according to demographic data. The prevalence of bovine aortic arch was higher in African and South American populations than in North American populations. Also, 24.2% of African populations and 26.8% of South American populations had bovine arch type B.[28] There are no data for Asians or Indians. Our study found that 22% of people with strokes and 3% of people without strokes had a bovine aortic arch. Based on a study of the anatomy of the bovine aortic arch, Celikyay[20] hypothesized that due to the difficult anatomy (tight turns) in the brachiocephalic and LCC arteries, stenting via conventional routes (femoral artery access) is both difficult and risky. Knowing the bovine aortic arch before an endovascular procedure minimizes complications and shortens the duration of the procedure. For these patients, an arterial route such as the radial, brachial, or transcarotid arteries is usually preferable.[27] In addition, a Vitek (VTK), Simmons 2 (Sim 2), or 3 catheter can facilitate easy navigation through the bovine aortic arch. Furthermore, prior to carotid artery stenting[30],[31],[32] and thrombectomies,[33] the patient undergoing a CT angiogram of the head and neck vessels should include the arch of the aorta as well.[5]

 Conclusion



Bovine aortic arch has a significant association with anterior circulation strokes and younger-onset strokes without any significant association with gender. The proportion of left-sided and bilateral infarcts is higher than in a standard arch. It is best to opt for the brachioradial approach for endovascular procedures since navigation is more difficult. In addition to angiograms routinely performed, the arch of the aorta should be evaluated as well.

Future Direction

Other anatomical variants of vessels and their association with stroke can be studied.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

The bovine aortic arch has recently been identified as a risk factor for the younger onset of anterior circulation stroke and has a predisposition for bilateral anterior circulation stroke. Navigating during diagnostic or therapeutic procedures becomes challenging as well. Knowledge reduces the risk of complications.

References

1Syperek A, Angermaier A, Kromrey M, Hosten N, Kirsch M. The so called “bovine aortic arch”: A possible biomarker for embolic strokes? Neuroradiology 2019;61:1165-72.
2Gold M, Khamesi M, Sivakumar M, Natarajan V, Motahari H, Caputo N. Right-left propensity of cardiogenic cerebral embolism in standard versus bovine aortic arch variant. Clin Anat 2018;31:310-3. doi: 10.1002/ca.23045.
3Liechty JD, Shields TW, Anson BJ. Variations pertaining to the aortic arches and their branches; with comments on surgically important types. Q Bull Northwest Univ Med Sch 1957;31:136-43.
4Wacker F, Lippert H, Pabst R. Atlas der arteriellenVariationen. Klassifikation und Haufigkeit. 1st ed. Stuttgart: Thieme; 2017.
5Muller M, Schmitz BL, Pauls S, Schick M, Rohrer S, Kapapa T, et al. Variations of the aortic arch-A study on the most common branching patterns. Acta Radiol 2011;52:738-42.
6Berko NS, JainVR, Godelman A, Stein EG, Ghosh S, Haramati LB. Variants and anomalies of thoracic vasculature on computed tomographic angiography in adults. J Comput Assist Tomogr 2009;33:523-8.
7Jakanani GC, Adair W. Frequency of variations in aortic arch anatomy depicted on multidetector CT. Clin Radiol 2010;65:481-7.
8Natsis KI, Tsitouridis IA, Didagelos MV, Fillipidis AA, Vlasis KG, Tsikaras PD. Anatomical variations in the branches of the human aortic arch in 633 angiographies: Clinical significance and literature review. Surg Radiol Anat 2013;31:319-23.
9Ruken Z, Celikyay Y, Koner AE, Denız C, Acu B, Firat MM. Frequency and imaging findings of variations in human aortic arch anatomy based on multidetector computed tomographydata. Clin Imaging 2013;37:1011-9.
10Vucurevic G, Marinkovic S, Puskas L, Kovacevic I, Tanaskovic S, Radak D, et al. Anatomy and radiology of the variations of aortic arch branches in 1,266 patients. Folia Morphol 2013;72:113-22.
11Ergun O, Gunes Tatar I, Birgi E, Durmaz HA, Akçalar S, Kurt A, et al. Angiographic evaluation of branching pattern and anatomy of the aortic arch. Turk Kardiyol Dern Ars 2015;43:219-26.
12Piyavisetpat N, Thaksinawisut P, Tumkosit M. Aortic arch branches variations detected on chest CT. Asian Biomed 2011;5:817-23.
13Mustafa AG, Allouh MZ, Ghaida JHA, al-Omari MH, Mahmoud WA. Branching patterns of the aortic arch: A computed tomography angiography-based study. Surg Radiol Anat 2017;39:235-42.
14Ogeng'o JA, Olabu BO, Gatonga PM, Munguti JK. Branching pattern of aortic arch in a Kenyan population. J Morphol Sci 2010;27:51-5.
15Lale P, Toprak U, Kaya T. Variations in the branching pattern of the aortic arch detected with computerized tomography angiography. Adv Radiol 2015;66:44-52.
16Rea G, Valente T, Iaselli F, Urraro F, Izzo A, Sica G, et al. Multi-detector computed tomography in the evaluation of variants and anomalies of aortic arch and its branching pattern. Ital J Anat Embryol 2014;119:180-92.
17Satti SR, Cerniglia CA, Koenigsberg RA. Cervical vertebral artery variations: An anatomic study. AJNR Am J Neuroradiol 2007;28:976-80.
18Ribo M, Flores A, Rubiera M, Pagola J, Mendonca N, Rodriguez-Luna D, et al. Difficult catheter access to the occluded vessel during endovascular treatment of acute ischemic stroke is associated with worse clinical outcome. J Neurointerv Surg 2013;5:i70-3.
19Celikyay ZR, Koner AE, Celikyay F, Deniz C, Acu B, Firat MM. Frequency and imaging findings of variations in human aortic arch anatomy based on multidetector computed tomography data. Clin imaging 2013;37:1011-9.
20Karacan A, Turkvatan A, Karacan K. Anatomical variations of aortic arch branching: Evaluation with computed tomographic angiography. Cardiol Young 2014;24:485-93.
21Bhattacharyya N. The increasing workload in head and neck surgery: An epidemiologic analysis. Laryngoscope 2011;121:111-5.
22Etzioni DA, Starnes VA. The epidemiology and economics of cardiothoracic surgery in the elderly. In: Katlic MR, editor. Cardiothoracic Surgery in the Elderly. New York: Springer New York; 2011. p. 5-24.
23Moorehead PA, Kim AH, Miller CP, Kashyap TV, Kendrick DE, Kashyap VS. Prevalence of bovine aortic arch configuration in adult patients with and without thoracic, aortic, pathology. Ann Vasc Surg 2016;30:132-7.
24CasaL DC, Deaton DH, Ku DN. Role of high shear rate in, thrombosis. J Vasc Surg 2015;61:1068-80.
25Shalhub S, Schäfer M, Hatsukami TS, Sweet MP, Reynolds JJ, Bolster FA, et al. Association of variant arch anatomy with type B aortic dissection and hemodynamic mechanisms. J Vasc Surg. 2018 Dec;68(6):1640-1648. doi: 10.1016/j.jvs.2018.03.409. Epub 2018 May 24. PMID: 29804742.
26Poullis MP, Warwick R, Oo A, Poole RJ. Ascending aortic curvature as an independent risk factor for type A dissection, and ascending aortic aneurysm formation: A mathematical, model. Eur J Cardiothorac Surg 2008;33:995-1001.
27Malone CD, Urbania TH, Crook SE, Hope MD. Bovine aortic arch: A novel association with thoracic aortic dilation. Clin Radiol 2012;67:28-31.
28Patil ST, Meshram MM, Kamdi NY, Kasote AP, Parchand MP. Study on branching pattern of aortic arch in Indian. Anatomy Cell Biol 2012;45:203-6.
29Dumfarth J, Chou AS, Ziganshin BA, Bhandari R, Peterss S, Tranquilli M, et al. Atypical aortic arch branching variants: A novel marker for thoracic aortic disease. J Thorac Cardiovasc Surg 2015;149:1586-92.
30Werner M, Bausback Y, Braunlich S, Ulrich M, Piorkowski M, Friedenberger J, et al. Anatomic variables contributing to a higher periprocedural incidence of stroke and TIA in carotid artery stenting: Single center experience of 833 consecutive cases. Catheter Cardio vasc Interv 2012;80:321-8.
31Shaw JA, Gravereaux EC, Eisenhauer AC. Carotid stenting in the bovine arch. Catheter Cardiovasc Interv 2003;60:566-9.
32Faggioli GL, Ferri M, Freyrie A, Gargiulo M, Fratesi F, Rossi C, et al. Aortic arch anomalies are associated with increased risk of neurological events in carotid stent procedures. Eur J Vasc Endovasc Surg 2007;33:436-41.
33Snelling BM, Sur S, Shah SS, Chen S, Menaker SA, McCarthy DJ, et al. Unfavorable vascular anatomy is associated with increased revascularization time and worse outcome in anterior circulation thrombectomy. WorldNeurosurg 2018;120:e97683.