Free
Case Report  |   June 2011
Aortic Dissection With Vascular Abnormalities
Author Notes
  • From the Ohio Valley Medical Center in Wheeling, West Virginia. 
  • Address correspondence to D. Kade Rasmussen, DO, Emergency Medicine, 2000 Eoff St, Wheeling, WV 26003-3823.E-mail: krodeo85@yahoo.com 
Article Information
Cardiovascular Disorders / Emergency Medicine
Case Report   |   June 2011
Aortic Dissection With Vascular Abnormalities
The Journal of the American Osteopathic Association, June 2011, Vol. 111, 407-409. doi:10.7556/jaoa.2011.111.6.407
The Journal of the American Osteopathic Association, June 2011, Vol. 111, 407-409. doi:10.7556/jaoa.2011.111.6.407
Abstract

A limited number of cases have been reported in the medical literature in which aortic dissection occurs with an aberrant right subclavian artery and a common carotid trunk. The authors report the case of a 59-year-old man who presented to the emergency department with sudden onset pain of 30 minutes duration on the right side of the buttocks. After presentation, the patient developed chest pain, which radiated to the back. Computed tomography angiogram revealed a Stanford type A aortic dissection that extended down to the bifurcation of the iliac arteries. He was also found to have an aberrant right subclavian artery with a retroesophageal tract and a common trunk of the common carotid arteries. The patient was transferred to a tertiary care center and underwent surgery for aortic arch replacement. The authors also discuss the embryologic development of these vascular abnormalities.

Aortic dissection is a life-threatening disease in which the layers of the aortic wall separate. Although aortic dissection was first described over 200 years ago, surgical intervention was not available until the 1950s, when cardiopulmonary bypass was first introduced.1 Various presenting symptoms are associated with the disease, ranging from chest pain to numbness in an extremity. It is important to diagnose aortic dissection as soon as possible to enable repair; up to 33% of individuals with the disease will die within the first 24 hours and 50% will die within 48 hours of symptom onset.2 
We present a case of an atypical presentation of Stanford type A aortic dissection involving the left subclavian artery. The patient had several vascular anomalies, including an aberrant right subclavian artery with a retroesophageal tract that was included in the aortic dissection and a common trunk for the common carotid arteries. 
Report of Case
A 59-year-old man presented to the emergency department with complaints of sudden onset pain on the right side of the buttocks and the inability to move his right leg without great pain. He also described numbness in his right leg and foot. The symptoms had lasted approximately 30 minutes prior to arrival. Soon after presentation, the patient also developed mild midsternal chest pain with radiation to his back. The patient thought the pain in his buttocks was caused by sciatica, for which he had seen a chiropractor in the past. However, the patient described the pain as more intense than that associated with his prior sciatica-related back complaint. In addition to sciatica, the patient had a history of hypertension, migraines, and an enlarged prostate. Past surgical procedures included a cholecystectomy. The patient was taking metoprolol (25 mg daily) to control his blood pressure. 
Initial vital signs included the following: temperature, 97.4°F (36.3°C); pulse, 61 beats per minute; respiration, 16 breaths per minute; and blood pressure, 157/50 mm Hg. He rated the pain in his leg as 8 out of 10 on a visual analog scale, with 10 indicating extreme pain. Results from physical examination were notable for generalized diaphoresis. Findings from head, neck, cardiovascular, lung, and abdominal examinations were normal. Strength of pulses palpated on the left upper and left lower extremities were normal (2+). On the right upper extremity, strength of the radial pulse was decreased but present (1+). We were unable to palpate dorsalis pedis or popliteal pulses on the right (0). We were also unable to obtain a pulse in these regions using handheld Doppler ultrasonography. The patient had a greatly diminished right femoral pulse by palpation. Range of motion in all extremities was equal, but sensation in the right lower extremity was decreased. 
Laboratory test results were normal for complete blood cell count, comprehensive metabolic profile, international normalized ratio, and troponin I (0.02 ng/mL). Laboratory values were elevated for creatinine kinase (351 U/L) and creatinine kinase-MB fraction (8.7 ng/mL). Results of a portable chest radiograph were normal (Figure 1). 
Results of the electrocardiogram showed sinus bradycardia without ST-T segment abnormalities. The patient underwent a computed tomography angiogram of the thorax, abdomen, and pelvis. Results of the computed tomography angiogram of the chest showed a Stanford type A aortic dissection involving the left subclavian artery (Figure 2). In addition, the patient had a dissection flap extending into the aberrant right subclavian artery, which had a retroesophageal tract (Figure 2). He also had a common origin for the common carotid arteries (Figure 2). The dissection continued into the abdomen and extended into the left renal artery approximately 3 cm. The dissection continued into the bifurcation of the aorta and involved the left common iliac artery. Because of the patient's vascular anomalies, the cardiothoracic surgeon requested that the patient be transferred to a tertiary care center by helicopter. At the tertiary care center, the patient underwent surgery and the aortic arch was replaced. At 6-month follow-up, the patient was still receiving metoprolol (increased to 50 mg daily) for blood pressure control. He was active with minimal discomfort. 
Comment
Aberrant right subclavian artery (ARSCA) is the most common anomaly of the aortic arch.3 According to Edwards,3 the incidence rate for ARSCA is 0.48%, or about 1 in 200 individuals. A series of autopsies performed by Holzapfel4 found that, in patients with this anomaly, the ARSCA travels in a retroesophageal track 80% of the time, between the trachea and esophagus 15% of the time, and in front of the trachea 5% of the time. In 3 studies5-7on dissection of the aorta involving the ARSCA, 12 of 28 patients had a Stanford type A aortic dissection, as our patient had. The acute angle of the ARSCA may cause a weakening of the aortic wall, which could increase the risk of dissection.5 
In addition to the ARSCA, our patient had another vascular anomaly: a common trunk for the common carotid arteries. A search of the medical literature using the National Library of Medicine's PubMed database revealed a limited number of reported cases in which ARSCA occurs with a common trunk for the common carotid arteries and thoracic aortic dissection.8-10 In one of these cases, the patient was reported to have an aneurysm of the ARSCA.9 Another case, discovered during a routine cadaver dissection, involved an ARSCA and common trunk for the common carotid arteries but not aortic dissection.11 
Figure 1.
Radiograph of the chest of a 59-year-old man with aortic dissection (anteroposterior view).
Figure 1.
Radiograph of the chest of a 59-year-old man with aortic dissection (anteroposterior view).
The embryologic variation of the aorta has been discussed in many articles. These articles have focused on 2 major theories in the development of the aortic anomalies. The first theory, which involves the Rathke diagram,12 describes ventral and dorsal aortas with their 6 pairs of interconnecting branchial arches. In this theory, the right aortic arch 4 degenerates, which causes the right seventh cervical intersegmental artery and the right dorsal aorta that is caudal to it to fuse and become the ARSCA.13,14 
The second theory, first described by Edwards,3 involves a “double arch system.” This hypothesis involves a double aortic arch with a ductus arteriosus on each side. Each arch produces a common carotid and subclavian artery. The malformation of the ARSCA is formed by an interruption in the connection of the right arch between the right common carotid artery and the origin of the right subclavian artery. This interruption, in turn, causes the subclavian artery to lose its connection with the ventral part of the aorta. The right subclavian artery then connects to what was the dorsal portion of the right aortic arch.3,15,16 Poultsides et al14 describe how the third cervical aortic arches give rise to the carotid arteries. At 7 weeks gestation, the common carotid arteries have a common trunk and, if a failure of separation occurs at this stage, then a common carotid trunk will remain. 
These embryologic variations are important to be aware of when it comes to the repair of aortic dissection, because they could mandate a change in the surgical approach. For example, Kikuchi et al5 described a total arch replacement and additional “elephant trunk” procedure necessitated by the vascular anomalies. In this procedure, part of the prosthetic arch is left behind in the proximal descending aortic arch to help protect against a more severe dissection. 
High blood pressure is the largest risk factor for aortic dissection. During an acute dissection, the blood pressure and the contractility of the heart will propagate the dissection. Systolic blood pressure should be lowered to 100 mm Hg to 120 mm Hg, or the lowest tolerable blood pressure if this range is unreachable. In addition, the heart rate should be lowered to 60 beats per minute. Intravenous β-blockers such as labetalol hydrochloride and esmolol hydrochloride are the first line therapy. Other medication such calcium channel blockers maybe used only if β-blockers are contraindicated. Intravenous sodium nitroprusside may be used but only in conjunction with a β-blocker.2 
Figure 2.
Computed tomography angiogram of a 59-year-old man's chest depicting (A) axial view of an aberrant right subclavian artery (red arrow) with a dissection flap traveling behind the esophagus (blue arrow), (B) coronal view of an aberrant right subclavian artery (red arrow) with dissection flap, (C) axial view of a common origin of the common carotid arteries (red arrow) and aberrant right subclavian artery attaching to the descending aorta with dissection flap (blue arrow), and (D) coronal view of a common origin of the common carotid arteries (red arrow).
Figure 2.
Computed tomography angiogram of a 59-year-old man's chest depicting (A) axial view of an aberrant right subclavian artery (red arrow) with a dissection flap traveling behind the esophagus (blue arrow), (B) coronal view of an aberrant right subclavian artery (red arrow) with dissection flap, (C) axial view of a common origin of the common carotid arteries (red arrow) and aberrant right subclavian artery attaching to the descending aorta with dissection flap (blue arrow), and (D) coronal view of a common origin of the common carotid arteries (red arrow).
Conclusion
Because approximately half of patients with aortic dissection die within the first 48 hours of symptom onset, a quick diagnosis is essential. Physicians should be aware of the presenting symptoms of this disease as well as the potential vascular anomalies that can be associated with it. Embryologic variations can impact the surgical approach for aortic dissection repair. 
 Financial Disclosures: None reported.
 
Manchini MC. Aortic dissection. Medscape Web site. http://emedicine.medscape.com/article/425118-overview. Updated May 10, 2011. Accessed May 24, 2011.
Wiesenfarth JM. Emergent management of acute aortic dissection. Medscape Web site. http://emedicine.medscape.com/article/756835-overview. Updated May 24, 2011. Accessed May 25, 2011.
Edwards JE. Malformations of the aortic arch system manifested as vascular rings. Lab Invest. 1953;2(1):56-75.
Holzapfel G. Ungewohlicher ursprung and verlauf der arteria subclavia dextra. Anat Hefte. 1899;12:373-521.
Kikuchi K, Makuuchi H, Oono M, Murakami H, Suzuki T, Ando T. Surgery for aortic dissection involving an aberrant right subclavian artery. Jpn J Thorac Cardiovasc Surg. 2005;53(12):632-634.
Kawamoto S, Bluemke DA, Fishman EK. Aortic dissection involving an aberrant right subclavian artery: CT and MR findings. J Comput Assist Tomogr. 1998;22(6):918-921.
Weinberger G, Randall PA, Parker FB, Kieffer SA. Involvement of an aberrant right subclavian artery in dissection of the thoracic aorta: diagnostic and therapeutic implications. AJR Am J Roentgenol. 1977;129(4):653-655.
Li QL, Zhang XM, Zhang XM. Aortic dissection originating from an aberrant right subclavian artery. J Vasc Surg.. (2007). ;46(6):1270-1273.
Murzi M, Mariani M, Tiwari K, et al. Aberrant right subclavian artery aneurysm in coexistence with a common carotid trunk. Ann Thorac Surg. 2009;88(1):e8 .
Turkbey B, Hazirolan T, Canyigit M, Peynircioglu B, Cil BE. Coexistence of aberrant right subclavian artery and common carotid trunk: diagnosis with CT angiography. Eur J Radiol Extra. 2007;62(2):63-64. doi: 10.1016/j.ejrex.2007.02.007 .
Sangam MR, Anasuya K. Arch of aorta with bi-carotid trunk, left subclavian artery, and retroesophageal right subclavian artery. Folia Morphol (Warsz).. (2010). ;69(3):184-186.
Kimura-Hayama ET, Meléndez G, Mendizábal AL, Meave-González A, Zambrana GF, Corona-Villalobos CP. Uncommon congenital and acquired aortic diseases: role of multidetector CT angiography. Radiographics. 2010;30(1):79-98. doi: 10.1148/rg.301095061 .
Nayak RS, Pai MM, Prabhu LV, D'Costa S, Shetty P. Anatomical organization of aortic arch variations in the Indian population: embryological basis and review. J Vasc Bras. 2006;5(2):95-100.
Poultsides GA, Lolis ED, Vasquez J, Drezner AD, Venieratos D. Common origins of carotid and subclavian arterial systems: report of a rare aortic arch variant. Ann Vasc Surg. 2004;18(5):597-600.
Becker AE, Anderson RH. Malformations of the aortic arch. In: Becker AE, Anderson RH, eds. Pathology of Congenital Heart Disease. London, England: Butterworth-Heinemann;1981 : 321-338.
Daseler EH, Anson BJ. Surgical anatomy of the subclavian artery and its branches. Surg Gynecol Obstet. 1959;108(2):149-174.
Figure 1.
Radiograph of the chest of a 59-year-old man with aortic dissection (anteroposterior view).
Figure 1.
Radiograph of the chest of a 59-year-old man with aortic dissection (anteroposterior view).
Figure 2.
Computed tomography angiogram of a 59-year-old man's chest depicting (A) axial view of an aberrant right subclavian artery (red arrow) with a dissection flap traveling behind the esophagus (blue arrow), (B) coronal view of an aberrant right subclavian artery (red arrow) with dissection flap, (C) axial view of a common origin of the common carotid arteries (red arrow) and aberrant right subclavian artery attaching to the descending aorta with dissection flap (blue arrow), and (D) coronal view of a common origin of the common carotid arteries (red arrow).
Figure 2.
Computed tomography angiogram of a 59-year-old man's chest depicting (A) axial view of an aberrant right subclavian artery (red arrow) with a dissection flap traveling behind the esophagus (blue arrow), (B) coronal view of an aberrant right subclavian artery (red arrow) with dissection flap, (C) axial view of a common origin of the common carotid arteries (red arrow) and aberrant right subclavian artery attaching to the descending aorta with dissection flap (blue arrow), and (D) coronal view of a common origin of the common carotid arteries (red arrow).