Mid-Aortic Syndrome in a 3-Year-Old Girl Successfully Treated by Aorto–Aortic Grafting and Renal Artery Implantation into the Graft

Abstract

Mid-aortic syndrome, an uncommon acquired or congenital condition characterized by segmental narrowing of the abdominal or distal descending thoracic aorta, is frequently accompanied by ostial stenosis of the aorta's branches. If left untreated, it can result in life-threatening complications secondary to severe hypertension.

We report the case of a 3-year-old girl with congenital mid-aortic syndrome, who was diagnosed by chance in the course of a viral illness, and whose high blood pressure values were first dismissed as inaccurate. Attempts to achieve medical or endovascular control of her hypertension were unsuccessful. She was thereafter successfully treated by aorto–aortic bypass grafting, resection of the stenotic segments of both renal arteries, and implantation of the patent arterial segments into the graft.

Mid-aortic syndrome, an uncommon condition characterized by segmental narrowing of the abdominal or distal descending thoracic aorta, is frequently accompanied by ostial stenosis of its branches.^1–5 It can be acquired or congenital. Acquired causes of mid-aortic syndrome include neurofibromatosis, fibromuscular dysplasia, retroperitoneal fibrosis, Williams syndrome, mucopolysaccharidosis, giant cell arteritis (Takayasu disease, temporal arteritis), and acquired insults in utero or in early life that result in developmental disorders of the growing aorta.^1–13 Congenital mid-aortic syndrome is caused by a developmental anomaly in the fusion and maturation of the paired embryonic dorsal aortas and typically manifests itself in young patients.^6,14–19

We report the case of a 3-year-old girl with congenital mid-aortic syndrome, who was diagnosed by chance in the course of a viral illness and in whom high blood pressure values had at first been dismissed as inaccurate. Attempts to achieve medical or endovascular control of her hypertension were unsuccessful, so she was treated surgically.

Case Report

A 3-year-old girl was in apparent good health until 1 week before her admission to our department of pediatric nephrology due to proteinuria and hemoglobinuria. At the time of her initial presentation to her hometown pediatrician, she had an illness that seems to have been viral in nature. She was unwell, had been febrile for 1 day, had no appetite, refused to drink, was restless at night, woke up frequently, and had eyelid edema (first noticed by her parents). Her blood pressure was so extremely high (>200/100 mmHg) that no one believed the measured values.

Upon her admission in January 2010, the child looked well, but had mild signs of respiratory tract infection. She was well-grown with a weight of 15 kg (75th percentile) and a height of 103 cm (95th percentile). Her blood pressure, measured several times, reached 210/145 to 225/165 mmHg; her pulse was around 120 beats/min. A physical examination showed her heart and lungs to be normal, except for a soft murmur (grade 2/6) in her chest. A bruit was heard over the aorta in the abdomen. Her peripheral pulses were normal and symmetrically palpable.

The patient received medical treatment immediately after admission, while simultaneous attempts were made to discover the cause of her extremely elevated blood pressure. The complete blood count, serum electrolytes, urea, creatinine, liver, and coagulation tests were all normal, with the exception of a borderline serum potassium level (3.2 mmol/L). Proteinuria was not confirmed. Levels of thyroid hormones and serum catecholamines were normal, while serum aldosterone (2.35 nmol/L) and plasma renin activity (26.8 μg/L/hr) were elevated. Left ventricular hypertrophy with diastolic dysfunction was confirmed by echocardiography. Ultrasonographically, the kidneys looked normal (left, 65 mm; right, 73 mm), but Doppler showed pulsus tardus in both kidneys. Renovascular hypertension was suspected, and we proceeded to angiography, where the abdominal aorta and all its visceral branches, except for the inferior mesenteric artery, were found to be narrow. The ostium of the right renal artery was occluded, and the ostium of the left was subtotally narrowed. Robust collateral circulation was seen for both kidneys, as well as for the gut (Fig. 1). Whole-body magnetic resonance imaging (MRI) and magnetic resonance angiography showed isolated involvement of the abdominal aorta and its branches. The absence of MRI contrast uptake in the thickened abdominal aorta wall, the complete normalcy of inflammation values (erythrocyte sedimentation rate, C-reactive protein, procalcitonin, complement activity, antineutrophil cytoplasmic antibody, antinuclear antibody, extractable nuclear antigens, anticardiolipin, anti-β₂ glycoprotein I antibodies, and interleukin-6), and the robust collateral circulation all ran contrary to a diagnosis of acute vasculitis and were more in accord with congenital mid-aortic syndrome. In addition, the girl had no signs of neurofibromatosis and, on MRI, no signs of retroperitoneal fibrosis; Williams syndrome was excluded by genetic testing.

Fig. 1 Angiography shows robust collateral circulation due to narrowing of the abdominal aorta (arrowhead), narrowing of all its visceral branches except for the inferior mesenteric artery, and narrowing of the left renal artery (arrow). Note that the right renal artery is occluded.

An attempt to control her blood pressure medically was not very successful: the reading was still around 160/80 mmHg after 5 maximal doses of antihypertensive drugs. Therefore, percutaneous transluminal angioplasty of the abdominal aorta and left renal artery was performed, although the right renal artery was inaccessible to the balloon due to complete occlusion. Unfortunately, this technique was not successful in controlling the girl's blood pressure, due to extreme elastic recoil of the vessels (Fig. 2). We therefore proceeded to surgery.

Fig. 2 Angiogram reveals that percutaneous transluminal angioplasty of the abdominal aorta and left renal artery was not successful in controlling the girl's blood pressure due to extreme elastic recoil of these vessels and complete occlusion of the right renal artery.

Exposure of the subdiaphragmatic portions of the abdominal aorta and iliac arteries was followed by exposure and mobilization of both renal arteries. After heparinization, the aorta was cross-clamped immediately below the diaphragm and immediately above the bifurcation. The aorta was opened for end-to-side anastomosis. An aorto–aortic bypass graft was performed with a 12-mm Dacron tubular graft and secured with an interrupted, single 3-0 Prolene suture. After blood flow was instituted through the graft, the graft was partially clamped and both renal arteries were implanted after resection of the congenitally stenotic portions of the native renal artery ostia. Fully 1 cm of the right renal artery had to be resected due to total occlusion; this left only 3 cm of functional vessel, which rendered additional mobilization of the remaining artery impossible. On the other hand, the stenotic part of the left renal artery was much shorter (<1 cm), so we encountered no tension while sewing the artery to the graft. The artery were secured with interrupted 5-0 Prolene suture. The retroperitoneum was closed with a continuous silk suture. No drainage tube was inserted into the wound. The wounds were closed in layers.

After surgery, the patient experienced massive bleeding from the right renal artery anastomosis, which had been sewn under tension. The leaking point at the right anastomosis was secured with additional sutures. Due to hemorrhagic shock and multiorgan failure, the girl was treated at our intensive care unit for a month. The patient recovered completely. The surgical procedure was successful in controlling her hypertension. Her blood pressure was completely normal (110/65 mmHg) with the aid of only one antihypertensive drug, and her left ventricular hypertrophy with diastolic dysfunction subsided completely.

Four months after vascular surgery, magnetic resonance angiography of the abdominal aorta showed a well-functioning subdiaphragmatic aorto–aortic bypass graft with a smoothly passable left renal artery and a partially narrowed, yet passable, right renal artery (Fig. 3). On the other hand, a Doppler ultrasonogram 6 months later showed normal curves and velocities over both renal arteries, indicating that postoperative stenosis of the right renal artery was not as important as we had thought from viewing the first postoperative imaging studies.

Fig. 3 Magnetic resonance angiogram of the abdominal aorta 4 months after surgery shows a well-functioning subdiaphragmatic aorto–aortic bypass graft (arrowhead), an easily passable left renal artery, and a partially narrowed, yet passable, right renal artery (arrow).

Discussion

Mid-aortic syndrome usually presents as arterial hypertension and is commonly diagnosed in children after a long delay, because children are often asymptomatic, their blood pressure is not frequently measured, and high values are generally dismissed as inaccurate. Headache, early fatigue on exertion, and lower-limb claudication can also be presenting symptoms of mid-aortic syndrome.7,14,16,18,20 In addition, when mid-aortic syndrome is acquired, it can be accompanied by symptoms and signs of the causal disease.^1–13

The treatment of mid-aortic syndrome can be medical, endovascular, or surgical. In light of the poor prognosis of patients with mid-aortic syndrome who are managed conservatively (and these form the majority), surgery remains the treatment of choice. In most patients, however, an attempt to achieve medical control of hypertension is still mandatory before surgical intervention.1–5,7–10,13–16,18,20–27 In general, it is recommended that surgery be deferred until the child reaches full growth potential, but exceptions are made in cases of severe hypertension refractory to medical therapy.1,8,18,28 Endovascular treatment, primarily in the form of balloon angioplasty, has also been used with variable success in the treatment of mid-aortic syndrome.10,22–24,29–34

If left untreated, most patients with mid-aortic syndrome die before the age of 40 because of myocardial infarction, heart failure, intracranial hemorrhage, or aortic rupture.3,9,18,35,36 It was certainly the case with our patient that her initial blood pressure measurements were dismissed as inaccurate. Timely treatment of mid-aortic syndrome is highly advisable.

Most patients have failed to respond to medical treatment alone, and endovascular treatment has been shown to have little long-term success. On the other hand, surgical treatment has been shown to be curative in most patients and is therefore, in spite of its complexity, the treatment of choice in patients with mid-aortic syndrome.1–5,7–10,13–16,18,20–27,29–34

The timing of surgery depends on the severity of hypertension and the age of the patient. Although it is preferable to postpone surgery until a child has reached full growth potential, the presence of severe intractable hypertension requires immediate surgery independent of the age of the patient.1,8,18,28 We attempted to control the blood pressure in our patient medically, as well as with the endovascular procedure, but without much success. Due to her severe, intractable hypertension, we were obligated to proceed with surgery, even though the child was only 3 years old at the time.

Few published papers have documented the results of surgical treatment of mid-aortic syndrome in children. These have reported the almost exclusive use of bypass techniques: aorto–aortic, aorto–renal, or aorto–visceral. In most instances, autogenous vessels have been used for bypass, because prosthetic grafts of small diameter are liable to failure from thrombosis and occlusion. To the best of our knowledge, only 2 reports have been published concerning children whose renal arteries were resected and directly reimplanted into the aorto-aortic graft,^35,36 as was the case in our patient. Even though this operation is shorter in duration than the autogenous-vessel bypass procedure, it is technically harder to perform. The whole length of a renal artery in a 3-year-old child is only around 4 cm. In our patient, the right renal artery had to be resected due to total occlusion of a 1-cm segment. Additional mobilization of the remaining artery (3 cm in length) was impossible. In spite of our technical difficulties and our patient's major complication, we still believe that renal artery resection and direct reimplantation into the aorto–aortic graft is a better choice than autogenous-vessel bypass for a very young and growing child.

In conclusion, what we have learned and would like to share with others is that high blood pressure values in a child should not be dismissed as inaccurate, even when the child is asymptomatic. Such blood pressure values can be the first sign of an illness that might take a disastrous course if left untreated. We confirmed that medical and endovascular treatment of mid-aortic syndrome was of little value in our patient, which obligated us to treat her surgically, even though she was only 3 years old. Surgery remains the treatment of choice in patients with mid-aortic syndrome, although it can be technically challenging, especially in small children. Resection of the congenital stenotic portion of the native renal artery ostium and direct implantation into the aorto–aortic graft (if possible) seems better than constructing an aorto–renal bypass, for it avoids another bypass in a growing child.