Fetal echocardiography

The role of echocardiography in prenatal screening

Echocardiography (EchoCG) is recognized as the most informative method of prenatal visualization of congenital cardiovascular anomalies. Unlike routine ultrasound examinations, targeted EchoCG allows for a detailed study of the anatomy of all fetal heart structures. The physician evaluates the structure of the atria and ventricles, the integrity of the interatrial and interventricular septa, the condition of the valve apparatus, and the correct origin of the great vessels. Additionally, the method provides the opportunity to analyze the characteristics of intracardiac hemodynamics in real time. The optimal time for performing such advanced screening is considered to be the 2nd trimester of pregnancy, when the fetal cardiovascular system is already sufficiently developed for adequate visualization.

Action algorithm upon detecting fetal CHD

If fetal congenital heart disease is diagnosed based on prenatal echocardiography results, obstetric management is strictly regulated.

The first mandatory step is fetal karyotyping. This genetic test is necessary to confirm or rule out concomitant chromosomal abnormalities, which are frequently associated with structural heart defects.

Once a normal karyotype is confirmed, the further pregnancy management plan depends on the feasibility of surgical correction of the identified defect. The evaluation of condition curability is performed exclusively by a pediatric cardiovascular surgeon. This specialist determines the prognosis and plans the stages of surgical intervention both before and after the child's birth.

Postnatal verification: physical examination

After the birth of a child with a prenatally established diagnosis of CHD, a thorough clinical evaluation is performed. The primary diagnostic stage is auscultation, which confirms the presence of organic pathology. The physician evaluates:

• The character, localization, and radiation of heart murmurs.
• The presence of visible skin cyanosis.
• The character of the pulse in peripheral arteries. Comparing the pulse in the upper and lower extremities is extremely critical (a key sign for diagnosing coarctation of the aorta).
• Blood pressure (BP), which must be measured in all extremities.

Instrumental confirmation of the diagnosis

EchoCG remains the primary imaging modality after birth, especially for complex pathologies such as coarctation of the aorta or transposition of the great vessels. The mandatory minimum evaluation for a newborn also includes:

1. Pulse oximetry — monitoring of oxygen saturation (SpO2) to detect occult hypoxemia.
2. Electrocardiography (ECG) — basic screening for rhythm disturbances. It allows for the detection of asymptomatic forms of pathology (WPW syndrome, AV conduction blocks, wandering pacemaker, single extrasystoles). Important: sinus arrhythmia and isolated incomplete right bundle branch block (RBBB) in children are considered age-related norms.
3. Chest X-ray — helps identify specific signs, such as rib notching (indentations on the lower margins due to collateral blood flow development through intercostal arteries) in coarctation of the aorta.
4. Laboratory diagnostics — complete blood count (CBC) and acid-base balance (ABB) assessment to determine the degree of hypoxemia and metabolic shifts.

In complex cases (e.g., transposition of the great vessels), radiopaque methods are used: angiocardiography and right heart catheterization with a pulmonary vascular reactivity test.

Differential diagnosis and management

Structural changes detected on EchoCG must be differentiated from other diseases. In newborns and infants, CHDs are primarily differentiated from congenital carditis. In patients older than 3 years, acquired inflammatory diseases (acute rheumatic fever, infective endocarditis, non-rheumatic carditis) and myocardial pathologies (cardiomyopathies) come to the forefront.

Differential diagnosis is also performed with minor heart anomalies (patent foramen ovale, mitral valve prolapse, false tendons) and systemic hereditary connective tissue disorders (Marfan and Ehlers-Danlos syndromes).

Upon final diagnosis of CHD, especially in the presence of clinical symptoms and signs of hemodynamic impairment, the priority organizational step is referring the child for a consultation with a cardiovascular surgeon to determine the necessity and timing of surgical intervention.

Class and exam questions

What else to study on this topic

• Clinical features of cyanotic heart defects using the tetralogy of Fallot as an example
• Algorithms for neonatal pulse oximetry screening for critical CHDs (SpO2 threshold values)
• Radiopaque methods: right heart catheterization with a pulmonary vascular reactivity test
• Differential diagnosis of CHD with hereditary Marfan and Ehlers-Danlos syndromes
• Outcomes of acute rheumatic fever (ARF) and acquired valvular heart disease

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.