Mucopolysaccharidosis

Introduction: Stenotic aorto-arteriopathy (SAA) is a constellation of uncommon vascular diseases characterized by segmental stenosis of the aorta and its branches. Etiologies of SAA include Takayasu's arteritis (TA), fibromuscular dysplasia (FD), neurofibromatosis, Williams syndrome, mucopolysaccharidosis, and middle aortic syndrome (MAS). In the absence of associated physical stigmata, the differential considerations are limited to TA, FD, or MAS.

Case presentation: A twenty month old black male presented with one day history of cough, fever and shortness of breath. In the Emergency Department he was found to be in severe respiratory distress with wheezing that did not respond to conventional therapy. He was admitted to the Pediatric Critical Care Unit. Vital signs on admission were: heart rate (HR) 150/min, respiratory rate (HR) 68/min, blood pressure (BP) 160/90 mm Hg. He was intubated due to progressive acidosis and hypercarbia. The physical examination postintubation was remarkable for no wheezing, HR 120-130/rain, and persistent hypertension despite adequate sedation and analgesia. Four extremities BP was obtained: right ripper 160/90 mm Hg, left tipper 158/90 mm Hg, right and left lower extremity had a systolic pressure of 30 by Doppler. Pertinent physical findings included per)orbital edema, diffuse rales and rhonchis, harsh grade III/VI systolic ejection murmur at left upper sternal border radiating to the left lower sternal border. The femoral and popliteal pulses were detectable by Doppler. The dorsalis pedis pulse was not present. Hepatosplenomegaly was present. Laboratory values were: arterial blood gas (ABC) pH = 7.18, Pa[CO.sub.2] = 59, Pa[O.sub.2] = 79, base deficit of -8, hemoglobin = 7, hematocrit = 25, with normal white count and platelets, normal electrolytes except elevated SGOT = 119, treat)nine = 0.6 and BUN = 17, VDRL negative. Chest X-ray (CxR) revealed cardiomegaly, diffuse bibasilar infiltrates, and right lower lobe consolidation as well as pulmonary edema. The electrocardiogram had biventricular enlargement with right axis deviation. The transthoracic and transesophageal echocardiograms demonstrated concentric left ventricular (LV) hypertrophy with narrowing of the thoracic aorta distal to the left subclavian artery. The descending abdominal aorta appeared mildly hypoplastic. The actual coarctation "shelf" could riot be demonstrated therefore a gadolinium enhanced magnetic resonance arteriogram (MRA) was obtained. The study revealed progressive narrowing of the aorta distal to the take off of the left subclavian leading to a severely stenotic segment in the mid thoracic portion (T7). The major branches of the aorta were unremarkable. Surgical intervention was recommended due to complicated hypertension with secondary LV dysfunction and congestive heart failure. Intraoperative findings were described as a low coarctation of the aorta at T7 with proximal tubular hypoplasia extending over four vertebral segments from just below the ligamentum arteriosum (not involved) to the mid thoracic level. There was hyperemia, mild external narrowing, and progressive thickening with palpation, defining the surgical margins. The aorta was mobilized from below the diaphragm to the left carotid artery. The ligamentum was divided avoiding the phrenic and recurrent laryngeal nerves. The ligamentum was not pulled. After confirming the extent of resection, the area was transected and a beveled anastomosis was performed sacrificing two levels of intercostal arteries. Postoperatively there was no pressure gradient across the anastomosis. He was treated with esmolol and diuretics due to persistent hypertension. The gross and microscopic evaluation of the surgical specimen revealed immature fibromyxomatous intimal plaque, fibrosis with focal inflammation and disruption of the media and intima. The scattered inflammation was composed of lymphocytes, plasma cells, eosinophils and histocytes. These findings are suggestive of aortitis most likely TA. He was started on steroids and discharged home on metoprolol with a planned angiogram in 6 weeks.

Discussion: Aortitis with obliterative involvement of the great vessels and renal arteries is a rare disease not easily distinguished from other causes of vascular disease, such as FD or MAS. Takayasu's arteritis, is a chronic inflammatory disease of unknown etiology, primarily involving the aorta and its major branches, with changes most marked at branch points. The early stages of tire disease are characterized by granulomatous changes, with secondary alterations in the media and adventitia. The disease progresses towards sclerosis with intimal hyperplasia, medial degeneration, and adventitial fibrosis leading to obliterative changes in the aorta and other arteries. At the time of the diagnosis most patients have symptoms of vascular insufficiency and hypertension that may be due to renal artery involvement or acquired coarctation of the aorta leading to congestive heart failure. Coronary artery involvement may cause angina or myocardial infarction. Due to the great variability in the natural history and lack of pathoguomonic findings there are developed criteria for the classification of TA. Studies have shown a small number of young patients who do not completely fulfill the criteria. For such eases histopathologic diagnosis may be helpful. Takayasu's arteritis and FD are vaso-occlusive diseases. The signs and symptoms of the two disease processes reflect end-organ damage. Fibromuscular dysplasia the most common cause of occlusive renal artery disease and childhood hypertension is solely a histopathologic diagnosis. However, extensive aortitis with irregularity and diffuse narrowing is not a characteristic of FD. Middle aortic syndrome is an uncommon condition characterized by severe narrowing of the thoracic and abdominal descending aorta with involvement of the renal and visceral branches. The differentiation between MAS and TA may be difficult since there are no clear criteria distinguishing the two entities. Aortography is the only investigation diagnostic for MAS.

Conclusions: This case report highlights a number of important diagnostic and management essentials in patients with SAA. Takayasu's arteritis, fibromuscular dysplasia and middle aortic syndrome, are rare clinical entities in childhood, with similar clinical manifestations and resultant end-organ damage. The only essential difference in the therapy is the well-established role of glucocorticosteroids in high dose in TA. Angiography and biopsy remain the only tools in establishing an accurate diagnosis.

Arabella C. Stock, MD, J. Glickstein, MD, G. Crooke, MD, J. Weingarten-Arams, MD--Department of Pediatrics, Divisions of Critical Care and Pulmonary Medicine, Cardiology and Department of Cardiothoracic Surgery, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY 10467

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