With coarctation of the aorta, there is a need for drug prevention of infective endocarditis, correction of hypertension and heart failure. The elimination of the anatomical defect of the aorta is carried out only by surgery.
Cardiac surgery for coarctation of the aorta is carried out in the early stages (with a critical defect – up to 1 year, in other cases at the age of 1 to 3 years). Contraindications to surgical treatment of aortic coarctation are irreversible degree of pulmonary hypertension, the presence of severe or uncorrected comorbidities, end-stage heart failure.
The following types of open surgery have been proposed for the treatment of coarctation of the aorta:
- I. Local plastic reconstruction of the aorta: resection of the stenotic portion of the aorta with the imposition of an end-to-end anastomosis; direct isthoplasty with longitudinal dissection of stenosis and aortic suturing in the transverse direction; indirect isthmoplasty (using a flap from the left subclavian artery or a synthetic patch, with the imposition of a carotid-subclavian anastomosis).
- Ii. Aortic coarctation resection with prosthesis: with replacement of the defect by arterial homotransplantation or synthetic prosthesis.
- Iii. Creating bypass anastomoses: bypass bypass using the left subclavian artery, splenic artery, or a corrugated vascular prosthesis.
With local or tandem stenosis and the absence of pronounced calcification and fibrosis in the area of coarctation transluminal balloon dilatation of the aorta is performed. Postoperative complications may include the development of aortic reokarctation, aneurysm, bleeding; ruptures of anastomoses, thrombosis of reconstructed areas of the aorta; ischemia of the spinal cord, ischemic gangrene of the left upper limb, etc.
Coarctation of the aorta is a congenital anomaly of the aorta, characterized by its stenosis, as a rule, in a typical place – distal to the left subclavian artery, at the point of transition of the arc to the descending aorta. In pediatric cardiology, the aorta occurs with a frequency of 7.5%, while 2-2.5 times more often in males. In 60-70% of cases, aortic coarctation is combined with other congenital heart defects: open arterial duct (70%), ventricular septal defect (53%), aortic stenosis (14%), mitral valve stenosis or mitral valve insufficiency (3-5%), less often with the transposition of the great vessels. In some infants with coarctation of the aorta, severe extracardiac congenital malformations are detected.
Causes of aortic coarctation
In cardiac surgery, several theories of aortic coarctation are considered. It is believed that the basis of the defect is a violation of the confluence of aortic arches in the period of embryogenesis. According to the Skoda theory, coarctation of the aorta is formed due to the closure of the open arterial duct (OAD) with simultaneous involvement of the adjacent part of the aorta.
Obliteration of the Batallov duct occurs shortly after birth; at the same time walls of a channel fall down and cicatrize. With the involvement of the aorta wall in this process, its narrowing or complete fusion of the lumen occurs at a certain site.
According to the Anderson – Becker theory, the cause of coarctation may be the presence of the sickle-shaped ligament of the aorta, which causes the narrowing of the isthmus during obliteration of the PDA in the area of its location.
In accordance with the hemodynamic theory of Rudolph, coarctation of the aorta is a consequence of the characteristics of the fetal intrauterine circulation. During prenatal development, 50% of the blood ejection from the ventricles passes through the ascending aorta, 65% through the descending aorta, while only 25% of the blood enters the aortic isthmus. This fact is related to the relative narrowness of the aortic isthmus, which under certain conditions (in the presence of septal defects) is preserved and aggravated after the birth of a child.
Features of hemodynamics during aortic coarctation
A typical location of stenosis is the terminal part of the aortic arch between the arterial duct and the mouth of the left subclavian artery (aortic isthmus region). In this place coarctation of the aorta is detected in 90-98% of patients. Outside, the constriction may be in the form of an hourglass or waist with a normal diameter of the aorta in the proximal and distal sections.
The external narrowing, as a rule, does not correspond to the size of the internal diameter of the aorta, since in the lumen of the aorta there is an overhanging crescent fold or diaphragm, which in some cases completely overlap the internal lumen of the vessel. The length of the coarctation of the aorta can be from a few mm to 10 cm or more, but more often limited to 1-2 cm.
Stenotic change of the aorta at the point of transition of its arc to the descending part causes the development of two blood circulation modes in a large circle: there is arterial hypertension proximal to the site of the obstruction to blood flow, and the distal hypotension.
Due to the existing hemodynamic disturbances in patients with aortic coarctation, compensatory mechanisms are activated – left ventricular myocardial hypertrophy develops, stroke and minute volume increases, the diameter of the ascending aorta and its branches expands, and the network of collaterals expands. In children older than 10 years, atherosclerotic changes are already observed in the aorta and vessels.
Hemodynamic features during coarctation of the aorta are significantly influenced by concomitant congenital heart and vascular defects. Over time, changes occur in the arteries involved in the collateral circulation (intercostal, internal thoracic, lateral thoracic, scapular, epigastric, etc.): their walls become thinner and their diameter increases, predisposing to the formation of prestenotic and post-stenotic aortic aneurysms, aneurysms brain arteries, etc. Usually aneurysmal vasodilation is observed in patients older than 20 years.
The pressure of the tortuous and dilated intercostal arteries on the ribs contributes to the formation of uzurs (notches) at the lower edges of the ribs. These changes appear in patients with coarctation of the aorta over the age of 15 years.
Classification of aortic coarctation
Taking into account the localization of the pathological narrowing, coarctation is distinguished in the area of the isthmus, ascending, descending, thoracic, abdominal aorta. Some sources distinguish the following anatomical variants of the defect – preductal stenosis (narrowing of the aorta proximal to the confluence of the AAP) and postductal stenosis (narrowing of the aorta distalny the confluence of the AAP).
According to the criterion of a plurality of anomalies of the heart and blood vessels, A. V. Pokrovsky classifies 3 types of aortic coarctation:
- Type 1 – isolated aortic coarctation (73%);
- Type 2 – a combination of coarctation of the aorta with PDA; with arterial or venous discharge of blood (5%);
- Type 3 – a combination of coarctation of the aorta with other hemodynamically significant anomalies of the vessels and CHD (12%).
In the natural course of aortic coarctation, there are 5 periods:
- I (critical period) – in children under 1 year; characterized by symptoms of circulatory failure in a small circle; high mortality from severe cardiopulmonary and renal failure, especially when aortic coarctation is combined with other CHDs.
- II (adaptive period) – in children from 1 to 5 years; characterized by a decrease in the symptoms of circulatory failure, which is usually represented by fatigue and shortness of breath.
- III (compensatory period) – in children from 5 to 15 years; characterized by a predominantly asymptomatic course.
- IV (the period of development of relative decompensation) – in patients 15-20 years; in puberty, signs of circulatory failure increase.
- V (decompensation period) – in patients of 20-40 years; characterized by signs of arterial hypertension, severe left and right ventricular heart failure, high mortality
Symptoms of aortic coarctation
The clinical picture of aortic coarctation is represented by a multitude of symptoms; manifestations and their severity depend on the period of flow of the disease and related anomalies that affect intracardiac and systemic hemodynamics. In young children with coarctation of the aorta, growth retardation and weight gain can be noted. Symptoms of left ventricular failure predominate: orthopnea, shortness of breath, cardiac asthma, pulmonary edema.
At an older age, due to the development of pulmonary hypertension, complaints of dizziness, headache, palpitations, tinnitus, reduced visual acuity are characteristic. When coarctation of the aorta are frequent nosebleeds, fainting, hemoptysis, numbness and chilliness, intermittent claudication, cramps in the lower extremities, abdominal pain due to intestinal ischemia.
The average life expectancy of patients with coarctation of the aorta is 30-35 years, about 40% of patients die in a critical period (up to 1 year of age). The most frequent causes of death in the period of decompensation are heart failure, septic endocarditis, ruptures of aortic aneurysms, hemorrhagic stroke.
Diagnosis of aortic coarctation
On examination, attention is paid to the presence of an athletic body type (the predominant development of the shoulder girdle with thin lower limbs); increased pulsation of the carotid and intercostal arteries, weakening or absence of pulsation in the femoral arteries; increased blood pressure in the upper extremities with a decrease in blood pressure in the lower extremities; systolic murmur above the apex and base of the heart, on the carotid arteries, etc.
In the diagnosis of coarctation of the aorta, instrumental examinations play a crucial role: ECG, EchoCG, aortography, chest X-ray and X-ray of the heart with esophageal contrast, sensing of the heart cavities, ventriculography, etc.
Electrocardiographic data indicate overload and hypertrophy of the left and / or right heart, ischemic changes in the myocardium. The X-ray picture is characterized by cardiomegaly, protrusion of the pulmonary arch, a change in the configuration of the aortic arch shadow, and contraction of the ribs.
Echocardiography allows you to directly visualize aortic coarctation and determine the degree of stenosis. Older children and adults may have transesophageal echocardiography.
During catheterization of the heart cavities, prestenotic hypertension and poststenotic hypotension, a decrease in the partial pressure of oxygen in the poststenotic aorta are determined. With the help of ascending aortography and left ventriculography, stenosis is detected, its degree and anatomical variant are assessed. Coronary angiography for coarctation of the aorta is shown in the case of the presence of angina pectoris episodes, as well as when planning an operation for patients over 40 years old to exclude IHD.
Coarctation of the aorta should be differentiated from other pathological conditions that occur with symptoms of pulmonary hypertension: vasorenal and essential arterial hypertension, aortic heart disease, nonspecific aortitis (Takayasu disease).
Aortic Coarctation Prediction
The natural course of coarctation of the aorta is determined by the option of narrowing the aorta, the presence of other CHD and in general has a very poor prognosis. In the absence of cardiac surgery, 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 was performed before the age of 10 years.
Operated patients with aortic coarctation are under life supervision by a cardiologist and a cardiac surgeon; they are recommended to limit physical activity and stress, regular dynamic examinations to exclude postoperative complications. The outcome of pregnancy after reconstructive surgery for coarctation of the aorta is usually favorable.
In the process of pregnancy management, antihypertensive drugs are prescribed for the prevention of aortic rupture, and infectious endocarditis is prevented.