Congenital heart block is a rare condition in which there is an abnormal delay or blockage in the electrical conduction system of the heart, present at birth. This block can interfere with the normal rhythm of the heart, causing it to beat too slowly or irregularly.
Types of Congenital Heart Block:
There are three degrees of heart block, and they can occur at different levels of severity:
- First-degree heart block: This is the mildest form, where the electrical signals are delayed but still reach the ventricles. It usually does not cause symptoms and may not need treatment.
- Second-degree heart block: In this type, some electrical signals fail to reach the ventricles. It can cause the heart to skip beats, which may result in symptoms like dizziness or fainting.
- Third-degree (complete) heart block: This is the most severe form, where the electrical signals from the atria are completely blocked from reaching the ventricles. The ventricles may beat on their own at a much slower rate, which can lead to significant symptoms, including fatigue, fainting, and heart failure.
Causes of Congenital Heart Block:
Congenital heart block can occur due to several reasons:
- Maternal autoimmune disease: The most common cause is a maternal autoimmune condition, particularly lupus (systemic lupus erythematosus, SLE) or Sjogren's syndrome, where antibodies from the mother can cross the placenta and affect the baby’s heart. These antibodies can damage the electrical conduction system of the fetus.
- Genetic factors: In some cases, congenital heart block can run in families, suggesting a genetic predisposition.
- Idiopathic: In some cases, no specific cause is identified.
Symptoms:
Symptoms of congenital heart block can vary depending on the severity of the condition:
- Mild cases (first-degree heart block) may have no noticeable symptoms.
- Moderate cases (second-degree heart block) can lead to fatigue, dizziness, or lightheadedness due to irregular heartbeats.
- Severe cases (third-degree heart block) can cause symptoms such as:
- Fatigue
- Fainting (syncope)
- Shortness of breath
- Pale or blue skin color (cyanosis) due to insufficient blood flow
- Heart failure in severe cases, particularly if the slow heart rate leads to poor blood circulation.
Diagnosis:
Congenital heart block is typically diagnosed through:
- Electrocardiogram (ECG): This test records the electrical activity of the heart and helps identify the type and degree of heart block.
- Fetal echocardiography: In cases where a mother has autoimmune disease, fetal heart block can sometimes be detected during pregnancy using ultrasound.
- Physical examination: Doctors may also identify abnormal heart rhythms through auscultation (listening to the heart with a stethoscope) or palpation of the pulse.
Treatment:
The treatment for congenital heart block depends on the severity and symptoms:
- Mild cases (first-degree heart block) may require no treatment or only regular monitoring.
- Moderate cases (second-degree heart block) may require medications or pacing devices to help regulate the heart's rhythm.
- Severe cases (third-degree heart block) often require a pacemaker, which is a device implanted under the skin to regulate the heart rate. In infants, a temporary pacemaker may be used until a permanent pacemaker can be implanted, usually when the child is older.
Prognosis:
- The outlook for children with congenital heart block depends largely on the degree of heart block and the presence of symptoms. Mild cases may not affect the child’s quality of life and may resolve on their own.
- Severe cases with third-degree heart block usually require pacemaker implantation to prevent complications such as heart failure, and with proper treatment, most children can live normal or near-normal lives.
- Regular follow-up with a cardiologist is often necessary, especially for those with more severe forms of heart block, to monitor heart function and ensure the pacemaker is working properly.
