Middle Aortic Syndrome in a 68‐Year‐Old Woman

Abstract

To the Editor: Middle aortic syndrome (MAS) is a rare condition characterized by a narrowing of the abdominal aorta and its branches; it typically presents with renovascular hypertension in children and young adults. Herein is described a case of infrarenal MAS in a 68-year-old woman who was otherwise asymptomatic. It was encountered incidentally during an examination of a T12 osteoporotic compression fracture. A 68-year-old woman was transferred to the hospital for a T12 osteoporotic compression fracture that was subsequently confirmed using computed tomography (CT) and magnetic resonance imaging (MRI) of the thoracolumbar spine. Because her backache was severe, an immediate vertebroplasty was scheduled. She was otherwise asymptomatic. Her medical history was unremarkable except for a 10-year history of hypertension, which was effectively controlled with amlodipine 5 mg/d. On routine physical examination, weak bilateral femoral and pedal pulses were noted; her blood pressure was 120–110/80–70 mmHg in the upper extremities and 90–80/70–50 mmHg in the lower extremities. Duplex ultrasound scanning of the lower extremity arteries showed a bilateral pulsus parvus tardus pattern with no obstructive lesion, suggesting a stenosis above the aortoiliac arteries. Review of the spinal CT and MRI (Figure 1) revealed a narrowing of the infrarenal abdominal aorta that had initially been overlooked. The aorta was found to have a segmental tubular stenosis (35 mm long, 8 mm in diameter) just below the origin of the renal arteries. The aorta below the stenotic segment exhibited generalized hypoplasia, and the iliac system was also small, with diameters of 8 to 9 mm at each common iliac artery. The ascending aorta, aortic arch, and descending thoracic aorta were normal. There was no obvious stenosis in the renal arteries, celiac trunk, superior mesenteric artery (SMA), or inferior mesenteric artery (IMA). Compensatory dilation of the SMA and IMA was noted, which allows collateral flow to the legs, and she denied claudication or weakness in her legs. Routine blood tests were all normal except for slightly high C-reactive protein (1.1 mg/L; normal range <0.8 mg/L). With these findings, the diagnosis of MAS was reached. A percutaneous vertebroplasty for T12 was performed uneventfully under fluoroscopy guidance. Her backache improved immediately and dramatically after the operation. Because she was asymptomatic, and her hypertension was well controlled with lower doses of a single drug, no additional vascular examination was planned. She was discharged home the day after the procedure. During follow-up over 12 months, at 1-month intervals for the prescription of alendronate, she was still asymptomatic and maintained normal blood pressure while taking amlodipine 5 mg/d. MAS is a clinico-anatomical classification often used to describe segmental narrowing of the abdominal or distal descending thoracic aorta and ostial stenosis of its major branches, irrespective of its etiology and pathogenesis.1, 2 The most frequent manifestations of MAS are uncontrolled renovascular hypertension and arterial insufficiency of the lower extremities.1-4 Renovascular hypertension is particularly severe in individuals with suprarenal and interrenal involvement. If the stenosis is below the renal arteries, leg discomfort is the primary symptom.3, 5 Lower extremity ischemia occurs less frequently, probably secondary to the rich collateral circulation that develops distal to the stenotic region of the aorta.4, 6 In the present case, the patient showed lower body hypotension but no claudication. This is most likely due to collateral pathways between the SMA and IMA. A narrowing of the aorta below the renal arteries does not lead to life-threatening renovascular hypertension and therefore has a much better prognosis.6, 7 The infrarenal type may occur more commonly than reported because these individuals often remain asymptomatic and do not seek treatment.5 This observation seems to be confirmed in this patient. The diagnosis of MAS is usually made during childhood or young adulthood, although it may present at any age.1-4 There have been a few reported cases occurring in individuals aged 60 and older with related symptoms.6, 8 The current patient is remarkable for two reasons; she is the second oldest reported, and she had no symptoms and the MAS was found incidentally. It may be that severe stenosis presents at an early age, whereas less-severe stenosis presents later. In older adults, diminished blood flow distal to the stenosis may manifest as a pulse differential between the arms and legs and represent the first clinical manifestation of MAS, as in this case. In conclusion, MAS, although rare in elderly adults, should be considered when differential blood pressures or weak femoral pulses are present. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. Author Contributions: Paik and Seo were both involved in analysis and interpretation of data and preparation of manuscript. Sponsor's Role: None.