Corrected transposition of the main vessels: symptoms, diagnosis, treatment

Corrected transposition of the great vessels is considered a rare congenital heart defect. However, clinical abnormalities in corrected transposition of the great vessels are minimal and, most likely, the defect often remains undiagnosed. Corrected transposition of the great vessels is characterized by the following changes. The morphologically formed right ventricle with a tricuspid valve is located on the left, arterial blood circulates in it and the aorta, which occupies a left-sided position, branches off from it; the morphologically formed left ventricle with a bicuspid valve is located on the right. It receives venous blood, which is directed to the pulmonary artery, located to the right of the aorta. Corrected transposition of the great vessels is characterized by an abnormal location of the cardiac conduction system. The AV node is located at the lower part of the interatrial septum above and to the left of the central fibrous body, the bundle of His is elongated as it passes from the right to the left atrium, then to the posterior part of the interventricular septum. Hemodynamics in this anomaly without other concomitant congenital heart defects has no peculiarities, except for the age-related insufficiency of the arterial (tricuspid) valve, which is not adapted to functioning under high pressure conditions. The functional state of the myocardium of the right (left) ventricle is of great importance, since it pumps blood into the systemic circulation. With its dilation, relative "mitral" insufficiency may occur.

In the absence of other concomitant congenital heart defects, children have no complaints. Against the background of the abnormal location of the conduction system, attacks of paroxysmal tachycardia and high-grade AV block may occur, which is often attributed to possible myocarditis. Suspecting corrected transposition of the great vessels is possible based on electrocardiographic examination data: deviation of the electrical axis of the heart to the left from 0 to -20°, sometimes the Wolff-Parkinson-White phenomenon, signs of overload of the arterial ventricle, absence of the Q wave in the left chest leads and its presence in II, III, aVF and right chest leads. It should be remembered, however, that there are no specific ECG signs of corrected transposition of the great vessels.

This defect is often an accidental finding during echocardiographic examination. The main signs of the defect are:

• changes in the echogram of the tricuspid valve located behind the interventricular septum are evidence of ventricular inversion;
• echogram of the aorta located in front and to the left and the absence of contact between the arterial AV valve and the main vessels, which indicates an inverted arrangement of the vessels.

Cardiac catheterization and angiocardiography do not have any advantages over echocardiography; studies are carried out to clarify the nature of pulmonary hypertension.

Treatment of corrected transposition of the great vessels

In a variant not complicated by other congenital heart defects, with age there may be a need for arterial valve replacement in case of severe insufficiency.

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