Classification of defects
All congenital defects are divided into three main groups depending on whether blood mixes and how it affects skin color:
- With normal skin color (without blood mixing). Arterial and venous blood flow through their respective pathways without crossing. This group includes coarctation of the aorta, aortic stenosis, and pulmonary stenosis.
- Acyanotic (pale) type defects. Arterial blood shunts into the venous vessels. The patient's skin and mucous membranes become pale. Typical examples: atrial septal defect (ASD), ventricular septal defect (VSD), and patent ductus arteriosus (PDA).
- Cyanotic type defects. Venous blood shunts into the arterial circulation, which decreases blood oxygen saturation. Patients suffer from cyanosis, shortness of breath, and choking spells. This includes tetralogy of Fallot and transposition of the great arteries (TGA).
Most common acyanotic defects
Ventricular septal defect (VSD) is the most common defect. Children are pale and exhibit delayed development. Signs of pulmonary hypertension appear: shortness of breath, harsh breathing, moist rales. It is treated only surgically on a "dry" heart (using cardiopulmonary bypass or deep hypothermia).
Patent ductus arteriosus (Botallo's duct) (PDA) occurs in 10–18% of cases. It manifests with pallor, frequent pneumonia, and growth retardation. A key auscultatory sign is a rough systolic-diastolic murmur in the 2nd intercostal space to the left of the sternum. Surgery (ligation or endovascular duct embolization) can be performed at any age.
Severe cyanotic defects
Tetralogy of Fallot is the most common cyanotic defect. It includes four anatomical components:
- Ventricular septal defect;
- Dextroposition of the aorta (displacement to the right, "overriding aorta");
- Right ventricular outflow tract stenosis;
- Right ventricular myocardial hypertrophy.
It manifests with pronounced cyanosis, limited mobility, and hypercyanotic spells. It requires radical staged surgery under cardiopulmonary bypass.
Transposition of the great arteries (TGA) is characterized by the aorta originating from the right ventricle and the pulmonary artery from the left. It is extremely severe (average life expectancy without treatment is about 13 months). Surgery includes palliative procedures (creating an atrial-level shunt) and radical blood flow switching.
Coarctation of the aorta
This is a narrowing of the aorta, in which the child exhibits delayed development and infantilism. A key diagnostic sign is the absence of a pulse in the vessels of the lower extremities with good pulse volume and high blood pressure in the upper extremities. If the narrowing is mild, blood flow is compensated, and patients can survive to adulthood. Surgical treatment is usually performed at ages 3–10: resection of the narrowed segment with an end-to-end anastomosis or isthmoplasty using the left subclavian artery is performed.
Diagnostics
Clinical diagnostics of CHDs are often difficult, so special instrumental methods play a decisive role:
- Echocardiography (EchoCG) and Doppler sonography;
- Angiocardiography;
- Cardiac catheterization.
In extremely severe anomalies (e.g., cor biloculare or aortic arch atresia) incompatible with life, heart transplantation remains the only prospect.
Briefly: answers to topical questions
Which congenital heart defects belong to acyanotic defects?
Congenital acyanotic (pale) heart defects include those occurring without cyanosis, where arterial blood shunts into venous vessels. This group includes:
- Atrial septal defect
- Ventricular septal defect
- Patent ductus arteriosus
- Atrioventricular septal defect
- Common atrium
- Total anomalous pulmonary venous return
- Isolated pulmonary stenosis
What instrumental methods are used to diagnose congenital heart defects?
A complex of special instrumental methods is used to diagnose congenital heart defects. These include:
- Echocardiography (EchoCG) — the main method for visualizing the anatomical substrate.
- Doppler sonography — to assess hemodynamics and the direction of blood shunting.
- Electrocardiography (ECG) — to record rhythm, conduction, and signs of overload.
- Chest radiography — to assess heart size and the state of the pulmonary circulation.
- Angiocardiography and radiopaque methods.
- Cardiac catheterization.
What types of surgical operations are used to treat coarctation of the aorta?
Open and endovascular interventions are used for the surgical treatment of coarctation of the aorta. The main types of surgery:
- Resection of the narrowed part of the aorta — with an end-to-end anastomosis (for short lesions).
- Isthmoplasty (patch aortoplasty using the subclavian artery) — used for significant length of narrowing when an anastomosis is impossible.
- Aortic replacement — used less frequently.
- Percutaneous transluminal angioplasty — used to treat postoperative recoarctation.
Which congenital heart defects occur without mixing arterial and venous blood?
Defects with normal skin color occur without mixing arterial and venous blood. These include:
- Coarctation of the aorta
- Aortic stenosis
- Pulmonary stenosis
What palliative operations are performed for transposition of the great arteries?
Palliative operations aimed at creating a shunt for the mixing of arterial and venous blood at the atrial level are performed for transposition of the great arteries:
- Atrioseptostomy
- Atrioseptectomy
Triad of Fallot includes 3 features: ASD, pulmonary trunk stenosis, and right ventricular hypertrophy. Tetralogy of Fallot has 4 features (VSD, pulmonary stenosis, dextroposition of the aorta, RV hypertrophy).
Class and exam questions
Why is the pulse measured in the legs in aortic coarctation?
This is the main diagnostic sign of the anomaly: due to vascular narrowing, the pulse in the lower extremities is absent, while in the upper extremities it is well-filled against the background of elevated blood pressure.
How do acyanotic defects differ from cyanotic ones?
In the acyanotic («white») type, arterial blood is shunted into the venous bed, causing skin pallor. In the cyanotic («blue») type, venous blood enters the arteries, leading to cyanosis (bluish discoloration) and hypoxia.
Where is the murmur auscultated in patent ductus arteriosus?
This anomaly is characterized by a harsh systolic-diastolic murmur best auscultated in the 2nd intercostal space to the left of the sternum.
What else to study on this topic
- Hemodynamic correction in transposition of the great arteries
- Endovascular surgical methods (PDA embolization)
- Palliative surgery for cyanotic heart defects (atrioseptostomy)
- Rare cyanotic defects: tricuspid atresia
- Indications and prospects for neonatal heart transplantation
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