Coarctation of the aorta (CoA)

Definition

Coarctation of the aorta is a congenital segmental stenosis (or complete atresia) of the aorta in the region of the isthmus – the transition of the arch to the descending part; less often – in the descending, ascending, or abdominal sections. Coarctation of the aorta is manifested in childhood by restlessness, cough, cyanosis, dyspnea, hypotrophy, fatigue, dizziness, palpitations, and nosebleeds. When diagnosing coarctation of the aorta, ECG data, chest X-ray, echocardiography, cardiac cavity catheterization, aortography, left ventriculography, and coronary angiography are considered. Methods of surgical treatment of coarctation of the aorta include transluminal balloon dilatation, isthmoplasty (direct and indirect), resection of coarctation of the aorta, bypass surgery.

General information

Coarctation of the aorta is a congenital anomaly characterized by its stenosis, usually in a typical location – distal to the left subclavian artery, at the transition of the arch to the descending aorta. In pediatric cardiology, coarctation of the aorta occurs with a frequency of 7.5% and 2-2.5 times more often in males. In 60-70% of cases, coarctation of the aorta is combined with other congenital heart defects: open ductus arteriosus (70%), interventricular septal defect (53%), aortic stenosis (14%), mitral valve stenosis or insufficiency (3-5%), less often with transposition of the main vessels. A proportion of newborns with coarctation of the aorta have severe extracardiac congenital anomalies.

Causes of coarctation of the aorta

According to the hemodynamic theory, the aorta’s coarctation is a consequence of the fetus’s intrauterine circulation. During intrauterine development, 50% of blood ejection from the ventricles passes through the ascending aorta and 65% through the descending aorta, while only 25% of blood enters the aortic isthmus. This fact is associated with the relative narrowness of the aortic isthmus, which, under certain conditions (in the presence of septal defects), persists and worsens after birth.

Features of hemodynamics in coarctation of the aorta

The typical location of stenosis is the terminal part of the aortic arch between the ductus arteriosus and the left subclavian artery mouth (the region of the aortic isthmus). Coarctation of the aorta is detected in 90-98% of patients at this location. Externally, the narrowing may have an hourglass or constriction appearance with normal aortic diameter in the proximal and distal portions. The external narrowing usually does not correspond to the size of the internal aortic diameter because the aortic lumen contains an overhanging sickle fold or diaphragm, which, in some cases, completely occludes the internal lumen of the vessel. The extent of aortic coarctation can range from a few mm to 10 or more cm but is more often limited to 1-2 cm.

Stenotic change of the aorta at the point of transition of its arch to the descending part causes the development of two modes of blood circulation in the great circle: arterial hypertension proximal to the place of blood flow obstruction and hypotension distal to it. In connection with the existing hemodynamic disorders in patients with coarctation of the aorta, compensatory mechanisms are activated – left ventricular myocardial hypertrophy develops, stroke and minute volume increase, the diameter of the ascending aorta and branches of its arch expands, the network of collaterals expands. In children over ten years of age, atherosclerotic changes are already noted in the aorta and vessels.

Classification of coarctation of the aorta

Considering the localization of pathological narrowing, coarctation is distinguished in the region of the isthmus, ascending, descending, thoracic, and abdominal aorta. Some sources distinguish the following anatomic variants of the malformation: preductal stenosis (aortic narrowing proximal to the PDA) and postductal stenosis (aortic narrowing distal to the PDA).

According to the criterion of multiple anomalies of the heart and vessels, three types of aortic coarctation are classified:

• Type 1 – isolated coarctation of the aorta (73%);
• Type 2 – a combination of coarctation of the aorta with PDA with arterial or venous effusion (5%);
• Type 3 – a combination of aortic coarctation with other hemodynamically significant vascular anomalies and congenital heart disease (12%).

There are five periods in the natural course of coarctation of the aorta:

• I (critical period) – in children under one year of age; characterized by symptoms of circulatory insufficiency in the small circle; high mortality from severe cardiopulmonary and renal failure, especially when aortic coarctation is combined with other heart defects.
• II (adaptive period): This period occurs in children from 1 to 5 years of age and is characterized by a decrease in the symptoms of circulatory insufficiency, which are usually represented by increased fatigue and dyspnea.
• III (compensatory period): This condition affects children from 5 to 15 years of age and is characterized by a predominantly asymptomatic course.
• IV (period of development of relative decompensation) – in patients 15-20 years old; in the period of puberty, signs of circulatory insufficiency increase.
• V (decompensation period) – in patients 20-40 years old; characterized by signs of arterial hypertension, severe left and right ventricular heart failure, and high mortality.

Symptoms of coarctation of the aorta

The clinical picture of coarctation of the aorta presents a variety of symptoms; the manifestations and their severity depend on the period of the course of the malformation and associated anomalies affecting intracardiac and systemic hemodynamics. In young children with coarctation of the aorta, growth retardation, and weight gain may be noted. Symptoms of left ventricular failure predominate orthopnea, dyspnea, cardiac asthma, and pulmonary edema.

Due to the development of pulmonary hypertension in older age, complaints of dizziness, headache, palpitations, tinnitus, and decreased visual acuity are characteristic. In coarctation of the aorta, nosebleeds, fainting, hemoptysis, numbness, chilliness, intermittent claudication, cramps in the lower extremities, and abdominal pain due to intestinal ischemia are not uncommon.

The average life expectancy of patients with coarctation of the aorta is 30-35 years, about 40% of patients die in the critical period (up to 1 year of age). The most frequent causes of death in the decompensation period are heart failure, septic endocarditis, ruptured aortic aneurysms, and hemorrhagic stroke.

Diagnosis of coarctation of the aorta

During examination, attention is drawn to the presence of an athletic type of physique (preferential development of the shoulder girdle with thin lower extremities), increased pulsation of the carotid and intercostal arteries, weakening or absence of pulsation in the femoral arteries; increased BP in the upper extremities with decreased BP in the lower extremities; systolic murmur over the apex and base of the heart, on the carotid arteries, etc.

Instrumental studies play a crucial role in diagnosing coarctation of the aorta: ECG, echocardiography, aortography, chest, and cardiac radiography with esophageal contrast, cardiac cavity probing, ventriculography, and others.

Electrocardiographic data indicate overload and hypertrophy of the left and/or right heart and ischemic myocardial changes. The radiological picture is characterized by cardiomegaly, bulging of the pulmonary artery arch, changes in the configuration of the aortic arch shadow, and rib usurations.

Echocardiography allows direct visualization of aortic coarctation and determination of the degree of stenosis. Transesophageal echocardiography can be performed in older children and adults.

Prestenotic hypertension and poststenotic hypotension, as well as decreased partial pressure of oxygen in the poststenoticaorta, are determined by cardiac cavity catheterization. Using ascending aortography and left ventriculography, stenosis is detected, and its degree and anatomic variant are assessed. Coronarography for aortic coarctation is indicated in the presence of episodes of angina pectoris, as well as when planning surgery for patients over 40 years of age to exclude CHD.

Treatment of coarctation of the aorta

In coarctation of the aorta, drug prophylaxis of infective endocarditis, correction of arterial hypertension, and heart failure are needed. Correction of anatomical aortic malformation is performed only surgically.

Cardiac surgery for coarctation of the aorta is performed early (in critical malformation – up to 1 year of age, in other cases at the age of 1 to 3 years). Contraindications to surgical treatment of coarctation of the aorta include irreversible degree of pulmonary hypertension, presence of severe or uncorrectable concomitant pathology, and terminal heart failure.

The following types of open surgery are currently proposed for the treatment of coarctation of the aorta:

• I. Reconstructive surgery: resection of the stenosed part of the aorta with end-to-end anastomosis; direct isthmoplasty with longitudinal dissection of the stenosis and cross-linking of the aorta; indirect isthmoplasty (using a flap from the left subclavian artery or synthetic patch, with carotid-subclavian anastomosis).
• II. Resection of aortic coarctation with a prosthesis: replacing the defect with arterial homograft or synthetic prosthesis.
• III. Creation of bypass anastomoses: bypass using the left subclavian artery, splenic artery, or vascular prosthesis.

Transluminal balloon aortic dilatation is performed in case of local or tandem stenosis and the absence of significant calcinosis and fibrosis in the coarctation area. Postoperative complications may include the development of aortic recurrent coarctation, aneurysms, bleeding, ruptures of anastomoses, thrombosis of reconstructed aortic sections, spinal cord ischemia, ischemic gangrene of the left upper extremity, etc.

All these treatment options are available in more than 580 hospitals worldwide (https://doctor.global/results/diseases/coarctation-of-the-aorta-coa). For example, Coarctectomy in children can be done in 21 clinics across Turkey for an approximate price of $12.2 K (https://doctor.global/results/asia/turkey/all-cities/all-specializations/procedures/coarctectomy-in-children). 

Prognosis for coarctation of the aorta

The natural course of aortic coarctation is determined by the variant of aortic narrowing and the presence of other heart defects. In general, it has an extremely unfavorable prognosis. In the absence of cardiac surgical care, 40-55% of patients die in the first year of life. With timely surgical treatment of aortic coarctation, good long-term results can be achieved in 80-95% of patients, especially if the operation is performed before the age of 10 years.

Operated patients with coarctation of the aorta are under the supervision of a cardiologist and cardiac surgeon for life; they are recommended to limit physical activity and loads and regular dynamic examinations to exclude postoperative complications. The outcome of pregnancy after reconstructive surgery for coarctation of the aorta is usually favorable. In the course of pregnancy management, hypotensive agents are prescribed to prevent aortic rupture, and infective endocarditis is prevented.