- Email: [email protected]
Higher Prevalence of Bovine Aortic Arch Configuration in Patients Undergoing Blunt Isthmic Aortic Trauma Repair
Journal Pre-proof Higher Prevalence of Bovine Aortic Arch Configuration in Patients Undergoing Blunt Isthmic Aortic Trauma Repair. Renato Mertens, MD, FACS, Fernando Velásquez, MD, Nicolás Mertens, MD, Francisco Vargas, MD, Ignacio Torrealba, MD, Leopoldo Mariné, MD, FACS, Michel Bergoeing, MD, Francisco Valdés, MD, FACS PII:
S0890-5096(19)30935-5
DOI:
https://doi.org/10.1016/j.avsg.2019.10.080
Reference:
AVSG 4742
To appear in:
Annals of Vascular Surgery
Received Date: 18 September 2019 Revised Date:
18 October 2019
Accepted Date: 20 October 2019
Please cite this article as: Mertens R, Velásquez F, Mertens N, Vargas F, Torrealba I, Mariné L, Bergoeing M, Valdés F, Higher Prevalence of Bovine Aortic Arch Configuration in Patients Undergoing Blunt Isthmic Aortic Trauma Repair., Annals of Vascular Surgery (2019), doi: https://doi.org/10.1016/ j.avsg.2019.10.080. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Elsevier Inc. All rights reserved.
1
Higher Prevalence of Bovine Aortic Arch Configuration in
2
Patients Undergoing Blunt Isthmic Aortic Trauma Repair.
3 4
Renato Mertens MD, FACS 1, Fernando Velásquez MD 1, Nicolás Mertens MD 2,
5
Francisco Vargas MD 1, Ignacio Torrealba MD 1, Leopoldo Mariné MD, FACS1, Michel
6
Bergoeing MD 1, Francisco Valdés MD, FACS 1.
7 8
Submitted as Original Article.
9 10 11
Departamento de Cirugía Vascular y Endovascular 1 y Departamento de Radiología 2,
12
Escuela de Medicina, Pontificia Universidad Católica de Chile.
13 14
Corresponding Author:
15
Renato A. Mertens, MD.
16
3990 Apoquindo #601, Las Condes, Santiago, Chile.
17
Phone: +56992323116
18
e-mail: [email protected]
19 20 21 22
1
23
ABSTRACT
24
INTRODUCTION. The prevalence of a bovine aortic arch configuration is higher in
25
patients treated for thoracic aortic aneurysms and type B dissection, its prevalence in
26
aortic isthmic trauma has not been described. MATERIAL AND METHODS. A Case
27
control study was performed comparing consecutive patients treated at our
28
institution for acute isthmic aortic transection after blunt trauma between 2002-2019
29
and a control group of consecutive sex matched individuals undergoing imaging for
30
non-aortic disease. Imaging and clinical findings were reviewed. Subjects were
31
divided into bovine and non-bovine groups and prevalence was compared. The length
32
of the aortic segment between the left subclavian artery (LSA) and the next proximal
33
great vessel was measured in the control population and a comparison was performed
34
between bovine and non-bovine aortic arch subjects. RESULTS. Thirty three
35
consecutive (30 male) patients were reviewed, 66 individuals (60 male) were
36
included in the control group. A higher incidence of bovine arch in trauma patients
37
was found: 57.6% vs. 34.8% (p=.007). The median (range, mm) and mean (SD)
38
distance between the bovine trunk and the LSA were 13 mm (2-27) and 12.4 mm (5.9)
39
respectively, compared with 5 mm (1-27) and 7.8 mm (6.1) between the left common
40
carotid and LSA in non-bovine aortic arches (p<.005). CONCLUSION. A higher
41
incidence of a bovine arch in patients reaching surgical treatment for traumatic
42
isthmic aortic transection was found in our population. Clinical interpretation of this
43
finding can lead to several alternatives. Confirmation with larger series and data on
44
prevalence of this anatomic variation in non-survivors is needed to provide a better
45
understanding of this finding.
2
46
Key words: aorta, trauma, bovine arch.
47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68
3
69
INTRODUCTION
70
Aortic trauma after a high-energy accident is a lethal condition, most patients die
71
before arrival to a medical facility (1,2,3). The mechanism of aortic rupture has been
72
related to acute deceleration with forward movement of the mobile aortic arch against
73
the rather stable descending aorta, fixed by the intercostal arteries to the spine. The
74
tear is usually located at the isthmic region: the transition area between the mobile
75
and fixed areas of the aorta, where the ligamentum arteriosum is located.
76
A bovine arch is the most common anatomic variation of the aortic arch (4), it is
77
defined as a common origin of the brachiocephalic trunk (BCT) and the left common
78
carotid (LCC) artery. It has been considered a misnomer, since the actual bovine arch
79
found in cattle and other domestic animals like goats and sheep is a single aortic trunk
80
from which all four great vessels originate (5) and common to other animals with
81
deep chests, where a long distance between the aortic arch and the thoracic inlet
82
would explain the presence of a single great vessel.
83
During development the truncus arteriosus, that later forms the aortic sac, receives six
84
pairs of branchial arches, these undergo selective apoptosis and the remaining vessels
85
constitute the aortic arch, its great vessels and the pulmonary arteries. The aortic sac
86
divides normally into two horns, the right will form the BCT and the left the LCC, if the
87
aortic sac fails to divide, the LCC will not separate from the BCT forming a bovine arch.
88
It is also important to understand that the segment of aortic arch between the LCC and
89
the LSA artery has a different embryological origin than the more proximal and distal
90
arch.
91
It has not been reported if this anatomical variation plays a role in aortic blunt trauma.
4
92
We report the prevalence of bovine aortic arch in patients undergoing blunt aortic
93
trauma repair and a sex matched Chilean population; in order to provide an objective
94
aortic anatomic difference between groups, we compared the length of the segment of
95
aorta between the LSA and the next proximal great vessel for bovine aortic arch
96
subjects and the more common three-vessel arch.
97 98
.
99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114
5
115
MATERIAL AND METHODS
116
A case control study of all patients treated for acute isthmic blunt aortic trauma at our
117
Institution between 2002 and 2019 was performed. Pre and postoperative contrasted
118
computed tomography imaging in arterial phase (CTA) were reviewed by two
119
observers. Bovine aortic arch was defined as a common aortic origin of the BCT and
120
LCC, both variants were included: 1.- The BCT and LCC arise from the aorta as a
121
common trunk with the division between both vessels located above the aortic arch
122
greater curvature and 2.- the LCC originates from the BCT (figure 1). Incidence was
123
calculated and compared with a sex matched control group of individuals undergoing
124
CTA at our Institution ordered for non-aortic disorders, mostly to rule out pulmonary
125
embolism. Individuals were excluded if an asymptomatic aortic aneurysm or
126
dissection was found. There is no other report of the prevalence of this anatomic
127
variation in Chile for comparison.
128
In the control group, the distance between the proximal edge of the origin of the LSA
129
and the distal edge of the bovine trunk or the LCC, for the 3 vessels arch anatomy, was
130
performed using Horos ® software (Horosproject.org, MD, USA). The linear distance
131
between vessels at the greater curvature of the arch was used. These measurements
132
were not performed in the trauma group due to anatomic distortion caused by the
133
transection.
134
Descriptive statistics, chi-square, Mann-Whitney and paired t test were used;
135
significance was defined as a p value of less than .05. Statistical analysis was
136
performed with Stata software (StataCorp LLC, TX, USA).
137
Approval by the Institutional Ethics Committee was obtained.
6
138
RESULTS
139
A total of 36 patients were treated for acute blunt aortic trauma at our Institution. All
140
of them by endovascular repair; there were no open surgical procedures during this
141
period. Mean age was 40.1 years (range 18 to 74), 31 (86.1%) were male. Trauma was
142
caused by motor vehicle accident in 31 subjects (86.1%) and fall from height in 5
143
(13.9%). Mortality after treatment at 30 days was 2.7 %. Two patients presented with
144
non-isthmic distal descending thoracic aortic tears and one patient with a traumatic
145
acute type B dissection, they were excluded from the study. CTA imaging was
146
available for the remaining 33 patients (30 male) included in the study. Sixty six
147
individuals (60 male) were included in the control group.
148
In the trauma group 57.6% of the patients presented a bovine aortic arch, in the
149
control group the prevalence was 34.8 % (p=.007).
150
In the control group the mean and median distance between the common TBC-LCC
151
trunk and the LSA were 12.4 mm (SD 5.9) and 13 mm (range 2-27 mm) respectively
152
for the bovine arch group and 7.8 mm (SD 6.1) and 5 mm (range 1-27 mm) between
153
the LCC and LSA for the 3 vessel arch anatomy group (p<.005). One patient with a
154
non-bovine right aortic arch and a very unusual anatomy was excluded from this
155
measurement. In the bovine arch group 60.9 % of the subjects had a distance of 12
156
mm or greater compared with 22 % in the 3-vessel group (p=.003).
157 158 159 160
7
161
4.- DISCUSSION
162
Aortic trauma after a high-energy accident is a lethal condition, most patients die
163
before reaching a medical facility based on historical data generated 60 years ago (1).
164
This has probably improved overtime with faster victim’s rescue and transportation
165
to dedicated trauma centers. Contemporary data still reports that 20 – 30% of the
166
patients dying after high-energy blunt trauma present an aortic tear (2,3).
167
An aortic bovine arch has been described in 13.6-14% of the European and USA
168
population (4,6), 14.6% in China (7), 18.3% in Peru (8), 11.4%-17.2% in Colombia
169
(9,10) and 34.5% in Argentina (11). A higher incidence has been reported in South
170
American (24.2%) and African (26.8%) populations compared to the US and Europe
171
in a metanalysis that included worldwide literature (4), but only two reports from
172
South America were considered (8,11). There are no prevalence reports from Chile.
173
The 34.8% incidence we found in our sex-matched (91% male) control group is higher
174
than described in other populations worldwide, but similar to the one described in
175
Argentina, our neighbour country (11).
176
A higher prevalence of bovine arch has been reported in patients with type B aortic
177
dissection and aneurysmal disease (6,12), type B dissection alone (13) and has also
178
been described as a possible predictor of increased long-term mortality in aortic
179
dissection (14). These findings have been challenged by other reports (7). An
180
increased shear stress on the inner curvature of the arch in patients with bovine arch
181
has been described as a possible cause to explain these findings (13).
182
A higher prevalence of a bovine aortic arch has also been described related to blunt
183
trauma of the aortic arch branches (15,16,17,18). This observation is based in a single
8
184
center experience (15); they found that 3 of 7 patients treated for blunt traumatic
185
lesions of the BCT had a bovine arch. Later on, a few reports of single cases have
186
derived into this conclusion. Since it is based on the prevalence found in very few
187
patients that arrived alive to a hospital and were diagnosed and treated, there is an
188
important bias: the prevalence in patients that expired before being diagnosed is
189
unknown, therefore concluding that a bovine arch is a risk factor facilitating rupture
190
may be mistaken.
191
We did find a higher incidence of a bovine aortic arch configuration in patients treated
192
for isthmic aortic blunt trauma.
193
We can reasonably assume that the prevalence of a bovine arch in subjects involved in
194
an accident is equal to the general population of the same sex in that area. The fact
195
that it is more prevalent in patients surviving long enough to be treated and up to
196
90% of the subjects with an unknown aortic arch anatomy never reach a hospital alive
197
(1,2,3) has two possible explanations. It may be a condition that facilitates the aortic
198
tear, as some concluded for the supra-aortic trunks, or it “protects” the patient after it
199
occurs preventing immediate exsanguinating hemorrhage and allowing treatment.
200
Anatomically, an obvious difference of the bovine and the more common 3-vessel arch
201
is a longer distance between the LSA and the common bovine trunk compared with
202
the LSA to LCC artery distance, as we demonstrated in our control group. This
203
segment of aorta has a different embryological origin than the rest of the arch. Even
204
though it is very hard to prove, it is possible that this longer segment of aorta provides
205
also a larger area of elastic tissue to dissipate the deceleration energy of the trauma,
206
probably causing a smaller tear and also providing a larger area of periadventitial and
9
207
mediastinal connective tissue that can potentially contain the rupture, therefore
208
preventing acute exsanguination.
209
Confirmation of this finding in a larger series and data on the incidence of bovine
210
aortic arch comparing survivors and non-survivors of blunt aortic trauma cannot only
211
increase the understanding of the mechanism of this lethal condition, but also provide
212
information to improve safety measures in vehicle design.
213
LIMITATIONS AND CONCLUSIONS
214
Aortic blunt trauma patients are not common; only two cases per year have been
215
treated at our Institution during the 17-year period reviewed. In a recent review the
216
average number of cases treated at institutions reporting results is only 25 patients
217
(19). The prevalence of bovine arch in subjects that do not survive the trauma and
218
never reach a hospital has not been reported to the best of our knowledge and is a
219
vital piece of information to allow firm conclusions.
220
Patients reaching treatment for isthmic aortic blunt trauma have a higher incidence of
221
a bovine aortic arch and therefore a longer distance between the LSA and the next
222
proximal great vessel. This finding and further research may provide a better
223
understanding of the mechanism of this highly lethal injury, the conditions that
224
facilitate survival and could eventually influence the design of safety measures.
225 226 227 228 229
10
230
REFERENCES
231
1.- Parmley L, Mattingly T, Manion W and Jahnke Jr, E. Nonpenetrating traumatic
232
injury of the aorta. Circulation 1958; 17: 1086–1101.
233
2.- Bertrand S, Cuny S, Petit P, Trosseille X, Page Y, Guillemot H and Drazetic
234
P. Traumatic rupture of thoracic aorta in real-world motor vehicle crashes. Traffic Inj
235
Prev 2008; 9: 153–161.
236
3.- Richens D, Kotidis K, Neale M, Oakley C and Fails A. Rupture of the aorta following
237
road traffic accidents in the United Kingdom 1992–1999. The results of the co-
238
operative crash injury study. Eur J Cardio-thoracic Surg 2003; 23: 143–148.
239
4.- Popieluszko P, Henry B, Sanna B, Hsieh W, Saganiak, K MD, Pękala P, Walocha J,
240
Tomaszewski K. A systematic review and meta-analysis of variations in branching
241
patterns of the adult aortic arch. J Vasc Surg 2018;68:298-306.
242
5.- Layton K, Kallmes D, Cloft H, Lindell E, Cox V. Bovine Aortic Arch Variant in
243
Humans: Clarification of a Common Misnomer. AJNR 2006;23:1541-42.
244
6.- Dumfarth J, Chou A, Ziganshin B, Bhandar R, Peterss S, Tranquilli M, Mojibian H,
245
Fang H, Rizzo J, Elefteriades J. Atypical aortic arch branching variants: A novel
246
marker for thoracic aortic disease. J Thorac Cardiovasc Surg 2015;149:1586-92 .
247
7.- Pullas Tapia G, Zhu X, Xu J, Liang P, Su G, Liu, H, Liu Y, Shu L, Liu S, Huang C.
248
Incidence of Branching Patterns Variations of the Arch in Aortic Dissection in Chinese
249
Patients. Medicine 2015;94:e795.
250
8.- Huapaya J, Chávez-Trujillo K, Trelles M, Dueñas R, Ferrandiz R. Anatomic variations
251
of the branches of the aortic arch in a Peruvian population. Medwave 2015;15:e6194
252
doi: 10.5867
11
253
9.- Rojas M, Muete W, Quijano Y. Anatomical variations of the aortic arch in a sample
254
of Colombian population. Rev Fac Med 2017;65: 49-54.
255
10.- Herrera N, Ballesteros L, Forero P . Caracterizacion de las Ramas del Arco Aó rtico
256
en una Muestra de Poblacion Colombiana. Un Estudio con Material de Autopsia. Int J
257
Morphol 2012;30:49-55.
258
11.- Yeri L, Gómez J, Fontaneto S, Espósito M. Variation of the origin of aortic arch
259
branches: in relationship with plates of atheroma. Int J Morphol.2011;29:182-186.
260
12.- Moorehead P, Kim A, Miller C, Kashyap T, Kendrick D, Kashyap V. Prevalence of
261
Bovine Aortic Arch Configuration in Adult Patients with and without Thoracic Aortic
262
Pathology. Annals of Vascular Surgery 2016;30:132-37.
263
13.- Shalhub S, Schä fer M, Hatsukami T, Sweet P, Reynolds J, Bolster F, Shin S, Reece T,
264
Singh N, Starnes B, Jazaeri O. Association of variant arch anatomy with type B aortic
265
dissection and hemodynamic mechanisms. J Vasc Surg 2018;68:1640-8.
266
14.- Mylonas S, Barkans A, Ante M, Wippermann J, Böckler D, Brunkwall J. Prevalence
267
of Bovine Aortic Arch Variant in Patients with Aortic Dissection and its Implications in
268
the Outcome of Patients with Acute Type B Aortic Dissection. Eur J Vasc Endovasc
269
Surg 2018;55:385-391.
270
15.- Graham J, Feliciano D, Mattox K, Beall A. Innominate vascular injury. J Trauma.
271
1982;22:647-55.
272
16.- Al-khaldi A, Robbins R. Successful repair of blunt injury of aortic archbranches in
12
273
the setting of bovine arch. J Vasc Surg 2006;43:396-8.
274
17.- Wells P, Estrera A. Blunt traumatic innominate pseudoaneurysm and left
275
common carotid occlusion with an associated bovine aortic arch. J Thorac Cardiovasc
276
Surg 2005;130:928-9.
277
18.- Moise M, Hsu V, Braslow B, Woo Y. Innominate artery transection in the setting of
278
a bovine arch. J Thorac Cardiovasc Surg 2004;128:632-4.
279
19.- Van der Zee C, Vainas T , van Brussel F, Tielliu I, Zeebregts C, van der Laan M.
280
Endovascular treatment of traumatic thoracic aortic lesions: a systematic review and
281
meta-analysis. The Journal of Cardiovascular Surgery 2019;60:100-10.
282 283 284 285
CONFLICT OF INTEREST STATEMENT: none
286
FUNDING: This research did not receive funding.
287
288 289 290 291 292
13
293
FIGURE LEGEND.
294
Figure 1, CTA of blunt aortic trauma patients. A. Three-vessel aortic arch, B. Bovine
295
arch, with a left common carotid originating from the brachiocephalic trunk.
296
14
S0890-5096(19)30935-5
DOI:
https://doi.org/10.1016/j.avsg.2019.10.080
Reference:
AVSG 4742
To appear in:
Annals of Vascular Surgery
Received Date: 18 September 2019 Revised Date:
18 October 2019
Accepted Date: 20 October 2019
Please cite this article as: Mertens R, Velásquez F, Mertens N, Vargas F, Torrealba I, Mariné L, Bergoeing M, Valdés F, Higher Prevalence of Bovine Aortic Arch Configuration in Patients Undergoing Blunt Isthmic Aortic Trauma Repair., Annals of Vascular Surgery (2019), doi: https://doi.org/10.1016/ j.avsg.2019.10.080. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Elsevier Inc. All rights reserved.
1
Higher Prevalence of Bovine Aortic Arch Configuration in
2
Patients Undergoing Blunt Isthmic Aortic Trauma Repair.
3 4
Renato Mertens MD, FACS 1, Fernando Velásquez MD 1, Nicolás Mertens MD 2,
5
Francisco Vargas MD 1, Ignacio Torrealba MD 1, Leopoldo Mariné MD, FACS1, Michel
6
Bergoeing MD 1, Francisco Valdés MD, FACS 1.
7 8
Submitted as Original Article.
9 10 11
Departamento de Cirugía Vascular y Endovascular 1 y Departamento de Radiología 2,
12
Escuela de Medicina, Pontificia Universidad Católica de Chile.
13 14
Corresponding Author:
15
Renato A. Mertens, MD.
16
3990 Apoquindo #601, Las Condes, Santiago, Chile.
17
Phone: +56992323116
18
e-mail: [email protected]
19 20 21 22
1
23
ABSTRACT
24
INTRODUCTION. The prevalence of a bovine aortic arch configuration is higher in
25
patients treated for thoracic aortic aneurysms and type B dissection, its prevalence in
26
aortic isthmic trauma has not been described. MATERIAL AND METHODS. A Case
27
control study was performed comparing consecutive patients treated at our
28
institution for acute isthmic aortic transection after blunt trauma between 2002-2019
29
and a control group of consecutive sex matched individuals undergoing imaging for
30
non-aortic disease. Imaging and clinical findings were reviewed. Subjects were
31
divided into bovine and non-bovine groups and prevalence was compared. The length
32
of the aortic segment between the left subclavian artery (LSA) and the next proximal
33
great vessel was measured in the control population and a comparison was performed
34
between bovine and non-bovine aortic arch subjects. RESULTS. Thirty three
35
consecutive (30 male) patients were reviewed, 66 individuals (60 male) were
36
included in the control group. A higher incidence of bovine arch in trauma patients
37
was found: 57.6% vs. 34.8% (p=.007). The median (range, mm) and mean (SD)
38
distance between the bovine trunk and the LSA were 13 mm (2-27) and 12.4 mm (5.9)
39
respectively, compared with 5 mm (1-27) and 7.8 mm (6.1) between the left common
40
carotid and LSA in non-bovine aortic arches (p<.005). CONCLUSION. A higher
41
incidence of a bovine arch in patients reaching surgical treatment for traumatic
42
isthmic aortic transection was found in our population. Clinical interpretation of this
43
finding can lead to several alternatives. Confirmation with larger series and data on
44
prevalence of this anatomic variation in non-survivors is needed to provide a better
45
understanding of this finding.
2
46
Key words: aorta, trauma, bovine arch.
47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68
3
69
INTRODUCTION
70
Aortic trauma after a high-energy accident is a lethal condition, most patients die
71
before arrival to a medical facility (1,2,3). The mechanism of aortic rupture has been
72
related to acute deceleration with forward movement of the mobile aortic arch against
73
the rather stable descending aorta, fixed by the intercostal arteries to the spine. The
74
tear is usually located at the isthmic region: the transition area between the mobile
75
and fixed areas of the aorta, where the ligamentum arteriosum is located.
76
A bovine arch is the most common anatomic variation of the aortic arch (4), it is
77
defined as a common origin of the brachiocephalic trunk (BCT) and the left common
78
carotid (LCC) artery. It has been considered a misnomer, since the actual bovine arch
79
found in cattle and other domestic animals like goats and sheep is a single aortic trunk
80
from which all four great vessels originate (5) and common to other animals with
81
deep chests, where a long distance between the aortic arch and the thoracic inlet
82
would explain the presence of a single great vessel.
83
During development the truncus arteriosus, that later forms the aortic sac, receives six
84
pairs of branchial arches, these undergo selective apoptosis and the remaining vessels
85
constitute the aortic arch, its great vessels and the pulmonary arteries. The aortic sac
86
divides normally into two horns, the right will form the BCT and the left the LCC, if the
87
aortic sac fails to divide, the LCC will not separate from the BCT forming a bovine arch.
88
It is also important to understand that the segment of aortic arch between the LCC and
89
the LSA artery has a different embryological origin than the more proximal and distal
90
arch.
91
It has not been reported if this anatomical variation plays a role in aortic blunt trauma.
4
92
We report the prevalence of bovine aortic arch in patients undergoing blunt aortic
93
trauma repair and a sex matched Chilean population; in order to provide an objective
94
aortic anatomic difference between groups, we compared the length of the segment of
95
aorta between the LSA and the next proximal great vessel for bovine aortic arch
96
subjects and the more common three-vessel arch.
97 98
.
99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114
5
115
MATERIAL AND METHODS
116
A case control study of all patients treated for acute isthmic blunt aortic trauma at our
117
Institution between 2002 and 2019 was performed. Pre and postoperative contrasted
118
computed tomography imaging in arterial phase (CTA) were reviewed by two
119
observers. Bovine aortic arch was defined as a common aortic origin of the BCT and
120
LCC, both variants were included: 1.- The BCT and LCC arise from the aorta as a
121
common trunk with the division between both vessels located above the aortic arch
122
greater curvature and 2.- the LCC originates from the BCT (figure 1). Incidence was
123
calculated and compared with a sex matched control group of individuals undergoing
124
CTA at our Institution ordered for non-aortic disorders, mostly to rule out pulmonary
125
embolism. Individuals were excluded if an asymptomatic aortic aneurysm or
126
dissection was found. There is no other report of the prevalence of this anatomic
127
variation in Chile for comparison.
128
In the control group, the distance between the proximal edge of the origin of the LSA
129
and the distal edge of the bovine trunk or the LCC, for the 3 vessels arch anatomy, was
130
performed using Horos ® software (Horosproject.org, MD, USA). The linear distance
131
between vessels at the greater curvature of the arch was used. These measurements
132
were not performed in the trauma group due to anatomic distortion caused by the
133
transection.
134
Descriptive statistics, chi-square, Mann-Whitney and paired t test were used;
135
significance was defined as a p value of less than .05. Statistical analysis was
136
performed with Stata software (StataCorp LLC, TX, USA).
137
Approval by the Institutional Ethics Committee was obtained.
6
138
RESULTS
139
A total of 36 patients were treated for acute blunt aortic trauma at our Institution. All
140
of them by endovascular repair; there were no open surgical procedures during this
141
period. Mean age was 40.1 years (range 18 to 74), 31 (86.1%) were male. Trauma was
142
caused by motor vehicle accident in 31 subjects (86.1%) and fall from height in 5
143
(13.9%). Mortality after treatment at 30 days was 2.7 %. Two patients presented with
144
non-isthmic distal descending thoracic aortic tears and one patient with a traumatic
145
acute type B dissection, they were excluded from the study. CTA imaging was
146
available for the remaining 33 patients (30 male) included in the study. Sixty six
147
individuals (60 male) were included in the control group.
148
In the trauma group 57.6% of the patients presented a bovine aortic arch, in the
149
control group the prevalence was 34.8 % (p=.007).
150
In the control group the mean and median distance between the common TBC-LCC
151
trunk and the LSA were 12.4 mm (SD 5.9) and 13 mm (range 2-27 mm) respectively
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for the bovine arch group and 7.8 mm (SD 6.1) and 5 mm (range 1-27 mm) between
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the LCC and LSA for the 3 vessel arch anatomy group (p<.005). One patient with a
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non-bovine right aortic arch and a very unusual anatomy was excluded from this
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measurement. In the bovine arch group 60.9 % of the subjects had a distance of 12
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mm or greater compared with 22 % in the 3-vessel group (p=.003).
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4.- DISCUSSION
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Aortic trauma after a high-energy accident is a lethal condition, most patients die
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before reaching a medical facility based on historical data generated 60 years ago (1).
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This has probably improved overtime with faster victim’s rescue and transportation
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to dedicated trauma centers. Contemporary data still reports that 20 – 30% of the
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patients dying after high-energy blunt trauma present an aortic tear (2,3).
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An aortic bovine arch has been described in 13.6-14% of the European and USA
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population (4,6), 14.6% in China (7), 18.3% in Peru (8), 11.4%-17.2% in Colombia
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(9,10) and 34.5% in Argentina (11). A higher incidence has been reported in South
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American (24.2%) and African (26.8%) populations compared to the US and Europe
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in a metanalysis that included worldwide literature (4), but only two reports from
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South America were considered (8,11). There are no prevalence reports from Chile.
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The 34.8% incidence we found in our sex-matched (91% male) control group is higher
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than described in other populations worldwide, but similar to the one described in
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Argentina, our neighbour country (11).
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A higher prevalence of bovine arch has been reported in patients with type B aortic
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dissection and aneurysmal disease (6,12), type B dissection alone (13) and has also
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been described as a possible predictor of increased long-term mortality in aortic
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dissection (14). These findings have been challenged by other reports (7). An
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increased shear stress on the inner curvature of the arch in patients with bovine arch
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has been described as a possible cause to explain these findings (13).
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A higher prevalence of a bovine aortic arch has also been described related to blunt
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trauma of the aortic arch branches (15,16,17,18). This observation is based in a single
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center experience (15); they found that 3 of 7 patients treated for blunt traumatic
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lesions of the BCT had a bovine arch. Later on, a few reports of single cases have
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derived into this conclusion. Since it is based on the prevalence found in very few
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patients that arrived alive to a hospital and were diagnosed and treated, there is an
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important bias: the prevalence in patients that expired before being diagnosed is
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unknown, therefore concluding that a bovine arch is a risk factor facilitating rupture
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may be mistaken.
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We did find a higher incidence of a bovine aortic arch configuration in patients treated
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for isthmic aortic blunt trauma.
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We can reasonably assume that the prevalence of a bovine arch in subjects involved in
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an accident is equal to the general population of the same sex in that area. The fact
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that it is more prevalent in patients surviving long enough to be treated and up to
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90% of the subjects with an unknown aortic arch anatomy never reach a hospital alive
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(1,2,3) has two possible explanations. It may be a condition that facilitates the aortic
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tear, as some concluded for the supra-aortic trunks, or it “protects” the patient after it
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occurs preventing immediate exsanguinating hemorrhage and allowing treatment.
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Anatomically, an obvious difference of the bovine and the more common 3-vessel arch
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is a longer distance between the LSA and the common bovine trunk compared with
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the LSA to LCC artery distance, as we demonstrated in our control group. This
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segment of aorta has a different embryological origin than the rest of the arch. Even
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though it is very hard to prove, it is possible that this longer segment of aorta provides
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also a larger area of elastic tissue to dissipate the deceleration energy of the trauma,
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probably causing a smaller tear and also providing a larger area of periadventitial and
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mediastinal connective tissue that can potentially contain the rupture, therefore
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preventing acute exsanguination.
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Confirmation of this finding in a larger series and data on the incidence of bovine
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aortic arch comparing survivors and non-survivors of blunt aortic trauma cannot only
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increase the understanding of the mechanism of this lethal condition, but also provide
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information to improve safety measures in vehicle design.
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LIMITATIONS AND CONCLUSIONS
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Aortic blunt trauma patients are not common; only two cases per year have been
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treated at our Institution during the 17-year period reviewed. In a recent review the
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average number of cases treated at institutions reporting results is only 25 patients
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(19). The prevalence of bovine arch in subjects that do not survive the trauma and
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never reach a hospital has not been reported to the best of our knowledge and is a
219
vital piece of information to allow firm conclusions.
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Patients reaching treatment for isthmic aortic blunt trauma have a higher incidence of
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a bovine aortic arch and therefore a longer distance between the LSA and the next
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proximal great vessel. This finding and further research may provide a better
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understanding of the mechanism of this highly lethal injury, the conditions that
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facilitate survival and could eventually influence the design of safety measures.
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REFERENCES
231
1.- Parmley L, Mattingly T, Manion W and Jahnke Jr, E. Nonpenetrating traumatic
232
injury of the aorta. Circulation 1958; 17: 1086–1101.
233
2.- Bertrand S, Cuny S, Petit P, Trosseille X, Page Y, Guillemot H and Drazetic
234
P. Traumatic rupture of thoracic aorta in real-world motor vehicle crashes. Traffic Inj
235
Prev 2008; 9: 153–161.
236
3.- Richens D, Kotidis K, Neale M, Oakley C and Fails A. Rupture of the aorta following
237
road traffic accidents in the United Kingdom 1992–1999. The results of the co-
238
operative crash injury study. Eur J Cardio-thoracic Surg 2003; 23: 143–148.
239
4.- Popieluszko P, Henry B, Sanna B, Hsieh W, Saganiak, K MD, Pękala P, Walocha J,
240
Tomaszewski K. A systematic review and meta-analysis of variations in branching
241
patterns of the adult aortic arch. J Vasc Surg 2018;68:298-306.
242
5.- Layton K, Kallmes D, Cloft H, Lindell E, Cox V. Bovine Aortic Arch Variant in
243
Humans: Clarification of a Common Misnomer. AJNR 2006;23:1541-42.
244
6.- Dumfarth J, Chou A, Ziganshin B, Bhandar R, Peterss S, Tranquilli M, Mojibian H,
245
Fang H, Rizzo J, Elefteriades J. Atypical aortic arch branching variants: A novel
246
marker for thoracic aortic disease. J Thorac Cardiovasc Surg 2015;149:1586-92 .
247
7.- Pullas Tapia G, Zhu X, Xu J, Liang P, Su G, Liu, H, Liu Y, Shu L, Liu S, Huang C.
248
Incidence of Branching Patterns Variations of the Arch in Aortic Dissection in Chinese
249
Patients. Medicine 2015;94:e795.
250
8.- Huapaya J, Chávez-Trujillo K, Trelles M, Dueñas R, Ferrandiz R. Anatomic variations
251
of the branches of the aortic arch in a Peruvian population. Medwave 2015;15:e6194
252
doi: 10.5867
11
253
9.- Rojas M, Muete W, Quijano Y. Anatomical variations of the aortic arch in a sample
254
of Colombian population. Rev Fac Med 2017;65: 49-54.
255
10.- Herrera N, Ballesteros L, Forero P . Caracterizacion de las Ramas del Arco Aó rtico
256
en una Muestra de Poblacion Colombiana. Un Estudio con Material de Autopsia. Int J
257
Morphol 2012;30:49-55.
258
11.- Yeri L, Gómez J, Fontaneto S, Espósito M. Variation of the origin of aortic arch
259
branches: in relationship with plates of atheroma. Int J Morphol.2011;29:182-186.
260
12.- Moorehead P, Kim A, Miller C, Kashyap T, Kendrick D, Kashyap V. Prevalence of
261
Bovine Aortic Arch Configuration in Adult Patients with and without Thoracic Aortic
262
Pathology. Annals of Vascular Surgery 2016;30:132-37.
263
13.- Shalhub S, Schä fer M, Hatsukami T, Sweet P, Reynolds J, Bolster F, Shin S, Reece T,
264
Singh N, Starnes B, Jazaeri O. Association of variant arch anatomy with type B aortic
265
dissection and hemodynamic mechanisms. J Vasc Surg 2018;68:1640-8.
266
14.- Mylonas S, Barkans A, Ante M, Wippermann J, Böckler D, Brunkwall J. Prevalence
267
of Bovine Aortic Arch Variant in Patients with Aortic Dissection and its Implications in
268
the Outcome of Patients with Acute Type B Aortic Dissection. Eur J Vasc Endovasc
269
Surg 2018;55:385-391.
270
15.- Graham J, Feliciano D, Mattox K, Beall A. Innominate vascular injury. J Trauma.
271
1982;22:647-55.
272
16.- Al-khaldi A, Robbins R. Successful repair of blunt injury of aortic archbranches in
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273
the setting of bovine arch. J Vasc Surg 2006;43:396-8.
274
17.- Wells P, Estrera A. Blunt traumatic innominate pseudoaneurysm and left
275
common carotid occlusion with an associated bovine aortic arch. J Thorac Cardiovasc
276
Surg 2005;130:928-9.
277
18.- Moise M, Hsu V, Braslow B, Woo Y. Innominate artery transection in the setting of
278
a bovine arch. J Thorac Cardiovasc Surg 2004;128:632-4.
279
19.- Van der Zee C, Vainas T , van Brussel F, Tielliu I, Zeebregts C, van der Laan M.
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Endovascular treatment of traumatic thoracic aortic lesions: a systematic review and
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meta-analysis. The Journal of Cardiovascular Surgery 2019;60:100-10.
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CONFLICT OF INTEREST STATEMENT: none
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FUNDING: This research did not receive funding.
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FIGURE LEGEND.
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Figure 1, CTA of blunt aortic trauma patients. A. Three-vessel aortic arch, B. Bovine
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arch, with a left common carotid originating from the brachiocephalic trunk.
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14