Idiopathic Mid-Aortic Syndrome in a Young Adult: A Case Report

VASCULAR DISEASE MANAGEMENT 2010;7:E245–E247

Abstract

Idiopathic mid-aortic syndrome is a rare condition characterized by narrowing of the abdominal aorta and stenosis of its major branches. Clinical presentation includes hypertension, claudication, renal failure and intestinal ischemia. Diagnosis is made by angiography. Treatment is necessary because of complications secondary to severe hypertension. We present a case of a 30-year-old male with an incidental finding of severe hypertension. Diagnosis was confirmed with computed tomographic angiography and magnetic resonance angiography. Optimal management in this patient is surgical bypass.

Introduction

Mid-aortic syndrome (MAS) is a rare condition found in children and young adults. MAS is characterized by narrowing of the abdominal aorta and stenosis of its major branches. Symptoms are usually secondary to hypertension, but claudication and intestinal ischemia may be present. Angiography is the gold standard of diagnosis. The goal of treatment is to normalize the patient’s blood pressure to avoid complications secondary to hypertension, to preserve renal function and to resolve claudication if present. The treatment of choice remains surgical revascularization, but antihypertensive drugs can be used as a bridge to surgery. We report a case of a 30-year-old male with an incidental finding of severe hypertension despite multiple antihypertensive drugs. Diagnosis was made with magnetic resonance angiography (MRA) and computed tomographic angiography (CTA). The patient was planned for aortoaortic bypass surgery with reimplantation of the renal and splanchnic arteries.

Case Report

A 30-year-old male was admitted to our hospital after a car accident. He sustained no major injury, but on examination, an elevated blood pressure of 213 mmHg systolic and 122 mmHg diastolic was found without any clinical symptoms. There was no history of headache, nausea or hot flushes, nor complaints of claudication. The patient never smoked. On his maternal side, a family history of hypertension was present. On clinical examination, a bruit was heard over the abdominal aorta. Pulsations in the groin were present. His serum concentrations of creatinine and electrolytes, urine analysis and renal ultrasound were normal. To treat his arterial hypertension a combination of thiazide, metoprolol and nifedepine was prescribed to the patient. However, no substantial decrease in blood pressure was observed at follow-up. MRA of the aorto-iliac arteries showed an abnormal aorta with an almost complete occlusion at the site of the renal arteries. There was extensive collateral blood flow through hypertrophic lumbal, epigastric and mesenteric arteries (Figure 1). To provide additional information on the involvement of the renal and mesenterial arteries, CTA was performed. This also demonstrated severe narrowing of the aorta from the level of the coeliac axis and downward to 5 cm above the orifice of the inferior mesenteric artery. The right renal artery showed a subtotal stenosis at the orifice with post-stenotic dilatation. The left renal artery showed a stenosis of approximately 50% at the orifice. Since no signs or symptoms of vasculitis were present (no fever, normal white blood cell count and no raised sedimentation rate) and the patient’s age made atherosclerosis unlikely, the diagnosis of idiopathic MAS was made. Because of his uncontrollable hypertension with maximum medical treatment, surgical intervention was advised. The patient was scheduled for aorto-aortic bypass surgery with reimplantation of the renal and splanchnic arteries. The patient was seen last 1 year after surgery and there were no complications reported due to surgery, also there were no physical complaints and his blood pressure was normal at time of follow-up.

Discussion

Mid-aortic syndrome was first described by Quain in 1847,¹ although it wasn’t until 1963 when Sen used the term “mid-aortic syndrome”.² It is a rare condition that accounts for 0.5–2% of all aortic narrowing,³ which mostly occur at the level of the proximal thoracic aorta, and is usually found in children and young adults. Hypertension is the cardinal clinical feature in MAS and is present in more than 90% of the cases.⁴ On clinical examination, weak or absent femoral pulses can be felt. An audible bruit can typically be heard over the aorta. Most often, the patient is asymptomatic, as in the case discussed here, but headache, nosebleed and fatigue are reported.⁵ Claudication and intestinal ischemia are present only in a minority of the patients,^6,7 probably due to the gradual development of stenosis, which gives the body time to create effective collateral pathways.⁴ There are multiple causes for this condition such as Takayasu’s disease, atherosclerosis, neurofibromatosis or Willliams syndrome.^7–9 It is suggested that a failure in fusion of the paired dorsal aortae during the fourth week of gestation is another cause of MAS.¹⁰ In approximately 60% of cases, no etiology can be found.⁴ Renal arteries are involved in about 90% of the cases, and the coeliac axis and superior mesenteric artery in 35–50%.^4,5 The inferior mesenteric artery is almost never affected.¹¹ A common histopathological finding in idiopathic MAS is fibroplasia of the intima and variable distortions of the internal elastic lamina with a lack of inflammatory changes.¹² The gold standard for the diagnosis of MAS remains conventional intra-arterial digital subtraction angiography.¹³ This technique produces excellent radiographic images of the abdominal aorta, although multiple lateral and oblique views of the aorta are necessary to evaluate the status of the renal and visceral arteries.⁶ Iodinated contrast material has to be used, which carries a risk of contrast nephrotoxicity, especially in patients with ischemic nephropathy. Furthermore, an arterial puncture is required and a complication rate of 3% is reported.¹⁴ MRA is a noninvasive technique capable of demonstrating detailed vascular anatomy. Also, multislice CTA can be used in diagnosis, as the acquisition of volumetric data that can be manipulated in infinite planes allows for comprehensive evaluation of thoracic and abdominal structures, vascular as well as non-vascular. This is a particular advantage of CTA over MRA.^15,16 The basic tenet of preoperative imaging, however, remains the same. Renal artery stenoses often involve short ostial lesions that are signaled by the presence of a dilated distal artery.¹⁷ The stenosis of the aorta in idiopathic MAS is situated in 19–52% of the cases at the level of the renal arteries. In 11–40% of the cases, the lesion is suprarenal, in 19–25% it is infrarenal and it is diffuse in 12% of cases.^18,19 Collateral vessels that circumvent a stenosis of suspicious character is prime evidence that the lesion is of hemodynamic importance.²⁰ Additional evaluation of idiopathic MAS consists of tests for baseline renal function, echocardiography and retinal exam. Although MAS is sometimes associated with carotid stenosis, there is no consensus yet regarding the need to evaluate the head and neck vessels for the presence of a bruit. The natural history of untreated symptomatic MAS is invariably death before the fourth decade due to complications secondary to severe hypertension such as cerebral hemorrhage or heart failure.^5,6,12 Therefore, treatment of this syndrome is necessary. Surgical correction remains the only definitive treatment when technically feasible. However, with newer and more effective antihypertensive drugs, surgery can be postponed until the patient reaches a more appropriate age. It is probably best to wait until full adult growth and adult vascular size are reached.¹ One-stage reconstruction with prosthetic and/or autogenous venous graft material is the preferred method.⁷ We believe that for the young adult, aorto-aortic bypass grafting with a Dacron tube, with or without direct reimplantation of the renal and splanchnic arteries to the graft, is the procedure of choice. Life table analysis of renal and splanchnic procedures revealed excellent patencies and no mortality due to this procedure.⁷ In one report, MAS was treated with balloon dilatation and stent implantation.²¹ We believe that this procedure is only applicable in a very small number of selected patients and cannot be used as a standard treatment option. Stanley et al⁷ reported significant improvement in hypertension after surgery and complete relief of symptoms in patients suffering from claudication and intestinal ischemia. Also, they reported no perioperative mortality following the primary aortic or combined aortic and visceral arterial reconstructive procedures.

Conclusion

Idiopathic MAS is a rare condition characterized by narrowing of the abdominal aorta and stenosis of its major branches. Angiography is the gold standard of diagnosis. Treatment is warranted because of severe complications secondary to hypertension. Surgery remains the treatment of choice, but with effective antihypertensive drug treatment, surgery can be postponed to an appropriate age. Bypass surgery for MAS appears to provide adequate long-term relief of hypertension and claudication.

Acknowledgement. We wish to thank vascular surgeon Dr. J.C.H. van der Waal and radiologist Dr. E. Tetteroo for their valuable assistance.

From the Department of Surgery, Amphia Hospital, Breda, The Netherlands. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted August 4, 2010, provisional acceptance given October 24, 2010, final version accepted November 3, 2010.

Department of Surgery, Amphia Hospital, Molengracht 21, Breda, The Netherlands 4800 RK. E-mail: kevin_de_leur@hotmail.com

REFERENCES

1. Kumar S, Bury RW, Roberts DH. Unusual case of refractory hypertension: Late presentation of the mid-aortic syndrome. Heart 2002;87:E3–E3.

2. Sen PK, Kinare SG, Engineer SD, Parulkar GB. The middle aortic syndrome. Br Heart J 1963;225:610–618.

3. Connely JE, Wilson SE, Laxrence PL, Fujitani RM. Middle aortic syndrome: Distal thoracic and abdominal coarctation, a disorder with multiple etiologies. J Am Coll Surg 2002;194:774–781.

4. Sethna CB, Kaplan BS, Cahill AM, et al. Idiopathic mid-aortic syndrome in children. Pediatr Nephrol 2008;23:1135–1142.

5. Panayiotopoulos YP, Tyrrell MR, Koffman G, et al. Mid-aortic syndrome presenting in childhood. Br J Surg 1996;83:235–240.

6. Sohn V, Herbert G, Arthurs Z, et al. Mid-aortic syndrome and renovascular hypertension in a 14-year-old Iraqi girl: Pitfalls in diagnosis and surgical management. Ann Vasc Surg 2007;21:648–651.

7. Stanley JC, Criado E, Eliason JL, et al. Abdominal aortic coarctation: Surgical treatment of 53 patients with thoracoabdominal bypass, patch aortoplasty, or interposition aortoaortic graft. J Vasc Surg 2008;48;1073–1082.

8. Petrak B, Bendova S, Seeman T, et al. Mid-aortic syndrome with renovascular hypertension and multisystem involvement in a girl with familiar neurofibromatosis von Recklinghausen type 1. Neuro Endocrinol Lett 2007;28:734–738.

9. Sumboonnanonda A, Robinson BL, Gedroye WMW, et al. Middle aortic syndrome: Clinical and radiological findings. Arch Dis Child 1992;67:501–505.

10. Stanley JC, Graham LM, Whitehouse WM Jr, et al. Developmental occlusive disease of the abdominal aorta and the splanchnic and renal arteries. Am J Surg 1981;142:190–196.

11. Lin YJ, Hwang B, Lee PC, et al. Mid-aortic syndrome: A case report and review of the literature. Int J Cardiol 2008;123:348–352.

12. Poulias GE, Skoutas B, Doundoulakis N, et al. The mid-aortic dysplastic syndrome. Surgical considerations with a 2 to 18 year follow-up and selective histopathological study. Eur J Vasc Surg 1990;4:75–82.

13. Lewis VD, Meranze SG, McLean GK, et al. The middle aortic syndrome: Diagnosis and treatment. Radiology 1988;167:111–113.

14. Egglin TKP, O’Moore PV, Feinstein AR, Waltman AC. Complications of peripheral arteriography: A new system to identify patients at increased risk. J Vasc Surg 1995;22:787–794.

15. Sanz J, Rajagopalan S. MR angiography of the abdominal aorta with protocols. In: Mukherjee D (ed). CT and MR Angiography of the Peripheral Circulation, 11th Edition. London: Informa Healthcare UK, 2007: pp. 247–261.

16. Rajagopalan S, Sanz J, Ribeizo V, Dellegrottaglie S. CT angiography of the thoracic aorta with protocols. In: Mukherjee D (ed). In: CT and MR Angiography of the Peripheral Circulation, 11th Edition. London: Informa Healthcare UK, 2007: pp. 91–111.

17. Messina LM, Goldstone J, Ferrell LD, et al. Middle aortic syndrome. Effectiveness and durability of complex arterial revascularization techniques. Ann Surg 1986;204:331–339.

18. Graham LM, Zelenock GB, Erlandson EE, et al. Abdominal aortic coarctation and segmental hypoplasia. Surgery 1979;86:519–529.

19. Onat T, Zeren E. Coarctation of the abdominal aorta. Review of 91 cases. Cardiologia 1969;54:140–157.

20. Stanley JC, Zelenock GB, Messina LM, Wakefield TW. Pediatric renovascular hypertension: A thirty-year experience of operative treatment. J Vasc Surg 1995;21:212–226. 21. Brzezinska-Rajszys G, Qureshi SA, Ksiazyk J, et al. Middle aortic syndrome treated by stent implantation. Heart 1999;81:166–170.