Midaortic syndrome (MAS) is an uncommon condition marked by a narrowing of the aorta as it passes through the chest and abdomen. This constriction reduces blood flow to the abdominal organs and legs. The condition predominantly affects children and young adults, forcing the heart to pump harder to circulate blood, which leads to numerous effects throughout the body.
Causes and Associated Conditions
The origins of midaortic syndrome are categorized as either congenital, meaning present at birth, or acquired. Congenital MAS results from a developmental anomaly during embryonic life where the aorta forms improperly. This can lead to a segment of the aorta being narrower than it should be from birth.
Acquired cases of MAS develop after birth and are often linked to other medical conditions. Inflammatory diseases that affect blood vessels, such as Takayasu’s arteritis, can cause the aortic wall to thicken and narrow. Certain genetic syndromes also have a known association with MAS, including neurofibromatosis type 1 (NF1), Williams syndrome, and Alagille syndrome, all of which can affect blood vessel development. In some instances, the direct cause remains unidentified.
Signs and Symptoms of Midaortic Syndrome
The most prominent sign of midaortic syndrome is severe high blood pressure (hypertension) that is often difficult to control with multiple medications. This hypertension is a direct result of the kidneys receiving insufficient blood flow, a condition known as renovascular hypertension. The body misinterprets this reduced flow as low blood pressure and releases hormones that raise the pressure throughout the body to dangerous levels.
Other symptoms stem from the restricted blood supply to various parts of the lower body. Individuals may experience significant pain or weakness in their legs after physical activity, a symptom known as claudication. Abdominal pain that begins after eating occurs because the digestive system lacks the blood flow needed for digestion. In children, the condition can manifest as a failure to grow properly, known as failure to thrive. Headaches, vision changes, and even seizures can also occur due to the effects of extreme hypertension on the brain.
The Diagnostic Process
Diagnosing midaortic syndrome often begins during a physical examination when a healthcare provider detects unusually high blood pressure, especially in a younger person. A key finding is a noticeable difference in blood pressure readings between the arms and the legs, with the pressure in the arms being much higher. An abdominal bruit, an abnormal whooshing sound heard with a stethoscope, may also be present due to turbulent blood flow through the narrowed aorta.
While physical findings raise suspicion, definitive diagnosis requires detailed imaging of the aorta. A Computed Tomography Angiogram (CTA) or a Magnetic Resonance Angiogram (MRA) are the primary tools used. These tests use contrast dye to create detailed maps of the blood vessels, showing the location, length, and severity of the aortic narrowing. In some cases, a more invasive catheter-based angiogram is performed, where a thin tube is guided through blood vessels to the aorta to inject dye directly, providing highly detailed images and allowing for pressure measurements.
Treatment Approaches for Midaortic Syndrome
Treatment for midaortic syndrome is tailored to the individual based on age, the anatomy of the narrowing, and overall health. The initial goal is to manage the severe hypertension to prevent damage to organs like the heart, kidneys, and brain. This involves a combination of several different types of antihypertensive medications, as hypertension associated with MAS is often resistant to treatment with a single drug.
The definitive treatment involves correcting the physical narrowing of the aorta. Open surgery is a common approach, especially for long segments of narrowing. One surgical technique is a bypass graft, where a tube is used to create a detour around the constricted section. Another option is patch aortoplasty, where the narrowed segment is surgically widened by sewing a patch of material into the aortic wall.
For some patients, less invasive endovascular procedures may be an option. Balloon angioplasty involves inserting a catheter with a small balloon at its tip into the narrowed artery, which is then inflated to stretch the vessel open. Often, a stent—a small, expandable metal mesh tube—is placed during angioplasty to help hold the artery open. The choice between open surgery and an endovascular approach depends heavily on the specific characteristics of the aortic lesion and the patient’s anatomy.
Long-Term Management and Outlook
Life after treatment for midaortic syndrome requires lifelong monitoring and care. Regular follow-up appointments with specialists are necessary to ensure the aorta and any surgical repairs, grafts, or stents are functioning properly. This often involves periodic imaging studies, such as CTA or MRA, to check for any new narrowing or complications.
Continuous management of blood pressure remains a focal point of long-term care, as hypertension can persist or recur even after a successful procedure. Patients may need to remain on blood pressure medications indefinitely.
With successful treatment and diligent follow-up, the outlook for individuals with midaortic syndrome is positive. Correcting the aortic narrowing can alleviate symptoms and significantly reduce the risks associated with severe hypertension. This allows many individuals to lead a good quality of life, with the ability to grow, develop, and participate in normal activities.