Coarctation of the aorta: symptoms, diagnosis, treatment

Coarctation of the aorta is a localized narrowing of the aortic lumen that leads to hypertension of the vessels of the upper extremities, left ventricular hypertrophy, and hypoperfusion of the abdominal organs and lower extremities. Symptoms of coarctation of the aorta vary depending on the degree of narrowing and its extent - from headache, chest pain, cold extremities, weakness and lameness to fulminant heart failure and shock. A soft murmur can be heard over the site of narrowing. Diagnosis is based on echocardiography or CT or MR angiography. Treatment of coarctation of the aorta is balloon angioplasty with stenting or surgical correction. Endocarditis prophylaxis is recommended.

Coarctation of the aorta accounts for 8-10% of all congenital heart defects. It is observed in 10-20% of patients with Shereshevsky-Turner syndrome. The ratio of boys to girls is 2:1.

Coarctation of the aorta usually occurs in the proximal thoracic aorta just below the origin of the subclavian artery. Rarely, coarctation of the abdominal aorta occurs. Coarctation may be an isolated defect or may be associated with other congenital anomalies (e.g., bicuspid aortic valve, ventricular septal defect, aortic stenosis, patent ductus arteriosus, mitral valve anomalies, cerebral aneurysms).

Physiologic consequences include increased pressure load on the left ventricle, left ventricular hypertrophy, hyperperfusion of the upper body including the brain, and hypoperfusion of the abdominal organs and lower extremities.

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Symptoms of coarctation of the aorta

There are two possible variants of coarctation of the aorta:

• isolated coarctation (adult type);
• coarctation of the aorta in combination with an open arterial duct, the narrowing of the aorta is located pre- or postductally (childhood type).

The infantile type of coarctation is the most unfavorable, as it is accompanied by the very early development of high pulmonary hypertension. Narrowing of the aorta blocks blood flow from the heart to the organs of the lower half of the body, as a result of which arterial pressure increases above the site of narrowing. This leads to the formation of body type features - an "athletic" body type with a well-developed shoulder girdle, as well as to the appearance of complaints characteristic of arterial hypertension (headaches, nosebleeds). With the natural course of the defect, morphological changes in the coronary arteries, secondary fibroelastosis of the endo- and myocardium of the left ventricle, cerebrovascular accidents or cerebral hemorrhages may develop, which also worsens the results of delayed surgical treatment.

With significant narrowing in the neonatal period, circulatory shock with renal failure (oliguria or anuria) and metabolic acidosis may develop, resembling the clinical picture of other systemic diseases, such as sepsis.

Less severe narrowing may not be clinically evident in the first year of life. Nonspecific symptoms of coarctation of the aorta (eg, headache; chest pain; weakness and limping with exercise) may develop as the child grows. Hypertension is common, but heart failure rarely develops after the neonatal period. Rarely, a cerebral aneurysm ruptures, resulting in subarachnoid or intracranial hemorrhage.

Typical physical examination findings include hypertension in the upper extremities. Femoral pulses are weak or delayed, and lower extremity blood pressure is low or undetectable. A 2-3/6 systolic ejection murmur is heard best over the left interscapular region. Dilated intercostal collateral arteries may produce a continuous murmur in the intercostal spaces. Girls with coarctation of the aorta may have Turner syndrome, a congenital disorder that causes lymphedema of the legs, pterygoid folds of the neck, square chest, cubitus valgus, and widely spaced nipples.

If left untreated, left ventricular heart failure, aortic rupture, intracranial hemorrhage, hypertensive encephalopathy, and hypertension may develop in adulthood.

Diagnosis of coarctation of the aorta

The diagnosis is suggested on the basis of clinical data (including blood pressure measurement in all 4 limbs), taking into account chest X-ray and ECG, and the exact diagnosis is established on the basis of two-dimensional echocardiography with color Doppler or CT or MR angiography.

Clinical diagnostics of coarctation of the aorta is specific, characteristic symptoms attract attention already at the first examination. The heart area is visually unchanged. The boundaries of relative cardiac dullness are not expanded. An intense systolic murmur is heard at the base of the heart, the point of maximum listening is between the shoulder blades at the level of the second thoracic vertebra. The pulse in the femoral artery is weakened or not palpable. Blood pressure in the legs is significantly reduced or not determined. If the defect is first detected at the age of over 1 year, this indicates its relatively minor severity. Severe coarctation of the aorta manifests itself already in the first months of life with anxiety, poor weight gain, and lack of appetite. Since measuring blood pressure in infants is difficult, the pulse in the femoral arteries is necessarily determined during the examination and its characteristics are assessed.

The ECG usually shows left ventricular hypertrophy, but the ECG may be normal. In newborns and infants, the ECG more often shows right ventricular hypertrophy or right bundle branch block than left ventricular hypertrophy.

Radiographically, it is possible to detect erosion of the lower edges of the ribs due to pressure of sharply dilated and tortuous intercostal arteries. The heart may have a spherical or "aortic", ovoid configuration with an elevated apex. Radiography of the chest organs demonstrates coarctation in the form of a "3" sign in the area of the shadow of the upper anterior mediastinum. The heart size is normal, unless heart failure develops. Dilated intercostal collateral arteries can erode the 3rd-8th ribs, as a result of which indentations appear on the ribs in the area of the lower contour, while rib erosions rarely form before the age of 5.

When scanning the aorta, a suprasternal position is used. Indirect echocardiographic signs confirming coarctation are poststenotic dilation of the aorta, hypertrophy and dilatation of the ventricles.

Cardiac catheterization and angiocardiography are indicated in cases where the nature of associated heart defects is unclear or there is a suspicion of aortic arch interruption.

Differential diagnostics are performed with all conditions accompanied by increased blood pressure. Significant weakening or absence of pulse in the femoral arteries indicates coarctation of the aorta. Similar clinical signs may be present in nonspecific aortoarteritis - an autoimmune disease in which a proliferative process develops on the inner lining of large vessels, resulting in a decrease in the lumen of the vessels and an increase in blood pressure. Due to the asymmetrical vascular damage, nonspecific aortoarteritis is called "the disease of different pulses."

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Treatment of coarctation of the aorta

Treatment is surgical. In children of the first months and years of life, the defect can be severe due to the small number of collaterals, which makes early surgical intervention necessary. If the course of the defect is not severe, then in order to avoid recoarctation at the correction site, it is better to postpone the operation until 6-14 years. Surgical treatment consists of resection of the narrowed section of the aorta and application of a synthetic patch to this section.

In clinically symptomatic neonates, stabilization of cardiopulmonary dysfunction is required, usually by infusion of prostaglandin E1 [0.05-0.10 mcg/(kg x min), then tapered to the lowest effective dose] to open the ductus arteriosus. Blood from the pulmonary artery can then flow into the descending aorta through the ductus, improving systemic perfusion and preventing the development of metabolic acidosis. Short-acting inotropic agents (eg, dopamine, dobutamine), diuretics, and O2 are used to treat heart failure.

Before correction, blockers can be used to treat hypertension; ACE inhibitors should be avoided. After surgery, blockers, ACE inhibitors, or angiotensin II receptor blockers are used to correct hypertension.

The preferred method for radical correction of the defect is debatable. Some centers prefer to perform balloon angioplasty with or without stenting, but others prefer surgical correction and reserve balloon angioplasty for recoarctation after surgical correction. The initial success rate after balloon angiography is 80-90%; subsequent catheterizations can be expanded as the child grows.

Surgeries to correct coarctation include resection and end-to-end anastomosis, patch aortoplasty, and left subclavian artery flap aortoplasty. The choice depends on the anatomy of the defect and center preference. Surgical mortality is less than 5% in symptomatic infants and less than 1% in older children. Residual coarctation often persists (6-33%). Rarely, paraplegia results from aortic clamping during surgery.

All patients, whether or not the defect has been corrected, should receive endocarditis prophylaxis before dental or surgical procedures that may result in bacteremia.