Coarctation of Distal Thoracic Aorta — The Middle Aortic Syndrome in an Elderly Female with Severe Coronary Artery Disease

ABSTRACT: Coarctation of the distal aorta or middle aortic syndrome is a segmental stenosis of the middle portion of the aorta, between the arch and the terminal bifurcation. Middle aortic syndrome is a rare disease of infants and young adults presenting with hypertension, lower limb claudication and renal insufficiency and is diagnosed by aortography or magnetic resonance angiography. Our case is unique because this condition was an incidental finding diagnosed during cardiac catheterization in a 70-year-old patient with hypertension in the absence of lower limb claudication. Recognition of this rare condition as a potential cause of secondary hypertension is important, especially given the wide age range of presentation. J INVASIVE CARDIOL 2010;22:E47–E48 Case Report. A 70-year-old female with past medical history of coronary artery disease, prior coronary artery bypass grafting in 1999, diabetes mellitus type 2, hypercholesterolemia, chronic kidney disease stage III and chronic hypertension on five anti hypertensive medications (Labetolol 200 mg TID, Hydralazine 50 mg three times daily, clonidine 0.3 mg BID, amlodipine 10 mg and benzapril 40 mg combination) presented to our institution with severe hypertension and congestive heart failure. On the day of admission she complained of chest pain and shortness of breath for a few hours duration and her blood pressure was 220/156 mmHg. She was tachypneic with normal heart sounds, no murmurs and bibasilar crackles on auscultation. Her chest X-ray revealed pulmonary vascular congestion and an EKG demonstrated ST segment depression in the inferior and lateral precordial leads. Her troponin T was 0.24 ng/ml (normal range 0.0–0.09). In addition to her anti-hypertensive treatment she received oxygen, nitroglycerin, and furosemide. This resulted in a significant clinical improvement in her symptoms. An echocardiogram showed moderate thickness of the left ventricular wall with no regional wall motion abnormality and an ejection fraction of 65%. Cardiac catheterization was performed after she was hemodynamically stabilized. It showed severe native three-vessel coronary artery disease with widely patent bypass grafts and left ventricular end diastolic pressure of 18mm Hg. Interestingly, hemodynamic assessment during catheterization was significant for a resting gradient of 50–55 mm Hg within the descending thoracic aorta distal to the site of typical coarctation (Figure 1). A follow-up MRA of the chest was reported as coarctation of the distal thoracic aorta with a residual lumen of 0.6–0.9 cm in diameter with no apparent collateral circulation (Figure 2). No intervention was done for the coarctation as the patient refused further aggressive management. She needed temporary hemodialysis after catheterization, and was discharged home after renal function returned to baseline and optimum blood pressure control was achieved. Discussion. The term “middle aortic syndrome” was first used by Sen et al1 to describe segmental stenosis of the middle portion of the aorta, between the arch and the terminal bifurcation. Sen described 16 patients in 1963, all under 30 years of age, with presenting symptoms of heart failure, intermittent claudication and chronic abdominal pain. Systemic hypertension was noted in all patients and a majority had a weak femoral pulse and a systolic bruit in the low interscapular or abdominal area. The coarctation was usually in the supradiaphragmatic area. Since then, few cases of middle aortic syndrome have been reported, predominantly those involving subdiaphragmatic aorta with renal and visceral artery involvement.^2,3 Middle aortic syndrome is a disease of infants and young adults. There have been only two reported cases occurring at advanced age (54 and 61 years) presenting with hypertension, lower limb claudication and renal insufficiency.4,5 We present a unique case of this condition presenting at the age of 70 as an incidental finding during cardiac catheterization. Notable also was the absence of obstructive symptoms such as limb claudication or an audible systolic murmur on auscultation of the back. The etiology of the middle aortic syndrome is not well understood. Some authors report a congenital origin of the disease but others believe it is secondary to aortitis. Histopathological examinations of the lesions have shown variable results, including severe atherosclerosis, cystic medial necrosis and medial degeneration with intimal atherosclerosis.6 Given the absence of obvious collateral circulation on MRA with multiple atherosclerosis risk factors in our patient, we postulate that subacute atherosclerotic disease of the distal thoracic aorta is a probable etiologic factor. This syndrome usually occurs as an isolated abnormality although it may be associated with Takayasu arteritis, Williams’s syndrome, neurofibromatosis and renal artery stenosis. ^7,8 The diagnosis of middle aortic syndrome has almost always been made by aortography. MRA can also be used to assess the severity of the obstruction in addition to providing anatomical information.9 Conventional aortography may still be necessary for detailed anatomic information about the collateral circulation. Medical management can be considered in treating asymptomatic patients with good blood pressure control. An ankle brachial index might be a useful non-invasive tool for monitoring. Endovascular procedures or surgical bypass grafting may be an option in patients with uncontrolled hypertension or symptoms of claudication. ^10–12 To the best of our knowledge, this is the first reported case of middle aortic syndrome in an elderly patient. This case highlights the importance of hemodynamic measurement during catherization in diagnosing this uncommon condition. The teaching point is to recognize that this condition may be asymptomatic, hence remain undiagnosed. Most importantly, it could be a potential cause of secondary hypertension at any age. A high degree of clinical suspicion is the key in the diagnosis of middle aortic syndrome and this could initiate appropriate investigation and will help in early diagnosis and avoid delays in treatment.

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From the Baystate Medical Center/Tufts University School of Medicine, Internal Medicine Department, Springfield, Massachusetts. The authors report no conflicts of interest regarding the content herein. Manuscript submitted July 23, 2009, provisional acceptance given August 11, 2009, final version accepted August 31, 2009. Address for correspondence: Siddharth A. Wartak MD, MRCP, Baystate Medical Center/Tufts University School of Medicine, Internal Medicine Department, 759 Chestnut Street, Springfield, MA 01199. E-mail: drwartak@gmail.com

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