Heart Block: Symptoms, Causes, and Diagnosis

Heart block is a type of disorder in the heart’s rhythm caused due to a defect in the natural pacemaker called SA node. It is caused by a block or an obstruction in the electrical conductivity system of the heart, from the atria (upper chambers) to the ventricles (lower chambers). The heart muscles contract due to the electrical signals and cause the heart to beat. A heart rate of fewer than 60 beats per minute is known as bradycardia. 

Heart blocks are of three types, First-degree, Second-degree, and Third-degree heart block. The First-degree heart block is the mildest form of heart block. In this, electrical signals pass slowly through the heart but reach the ventricles. Generally, it does not cause symptoms. The Second-degree heart block has irregular heart rhythm and the Third-degree heart block is the most critical form. In this, the heart rate is slower and irregular than usual.

Heart block may occur in children or adults. Children can be born with this disorder if they suffer from a congenital heart defect or can inherit it if their mother has an autoimmune disorder like lupus. This disorder is known as a congenital heart block. 

Some Common Facts about Heart Block

  • Heart block is a type of heart rhythm disorder
  • It is caused due to a defect in the natural pacemaker. 
  • It is commonly abbreviated as HB. 
  • Heart block is a type of arrhythmia. 
  • It is also called the atrioventricular block (AV). 
  • It may occur in children or adults. 
  • Sometimes, no cause of the heart block can be identified.
  • There are three types of heart block, 1st-degree heart block, 2nd-degree heart block, and 3rd-degree heart block. 
  • Ischemic heart disease is responsible for approximately 40% of cases of heart block.
  • Heart block is associated with cardiomyopathies, which include hypertrophic obstructive cardiomyopathy and infiltrative conditions like amyloidosis and sarcoidosis.
  • Infectious causes like rheumatic fever, endocarditis, viruses, Lyme disease, and autoimmune disease like systemic lupus erythematosus are also associated with heart block.
  • Medications, cardiac surgery, and inherited conditions are potential triggers of heart block. 

Causes of Heart Block

Heart block can be congenital or develops later in life. The causes of congenital heart block are:

  • Birth defect: The heart may not have developed accurately in the womb. 
  • Autoimmune disease: Disorders like lupus can be transferred by the mother in the form of proteins through the umbilical cord.

The causes of acquired heart block are:

  • Damage caused by a heart attack
  • Heart problems like inflammation of the heart muscle, clogged arteries, and heart failure
  • Rheumatic fever
  • Surgeries that affect the electrical system of the heart
  • Muscle disorders
  • Cardiomyopathy
  • Certain medications

Symptoms of Heart Block

Some of the symptoms of heart block are:

  • Abnormal heartbeats
  • Dizziness
  • Pain in the chest
  • Shortness of breath
  • Lightheadedness

The first-degree heart block has generally no noticeable symptoms. The Second-degree heart block has symptoms like:

  • Dizziness
  • Light-headedness
  • Fainting
  • Shortness of breath
  • Chest pain
  • Hypertension
  • Low blood pressure

The symptoms of Third-degree heart block are:

  • Bradycardia
  • Palpitations
  • Breathlessness
  • Fatigue
  • Fainting
  • Chest pain

Diagnosis of Heart Block

If there are signs and symptoms of heart block, then the doctor will conduct some tests to determine the heart’s condition. The first-degree heart block and second-degree heart block usually do not need treatment. To diagnose the condition, the doctor may consider these things:

  • ECG: Heart block can be diagnosed by an ECG (electrocardiogram). It records the electrical activity of the heart.
  • The overall health history
  • Medications, if any
  • Physical examination
  • Family history of heart disorder or heart block
  • Lifestyle choices, like using illegal drugs or smoking 
  • Implantable loop recorder


Heart block or atrioventricular block is a disorder of abnormal heart rhythm caused due to a defect in the natural pacemaker. If you are experiencing lightheadedness, dizziness, or fatigue, seek professional help as soon as possible.

The risk factors involved in Heart Block are:

  • Coronary thrombosis
  • Cardiomyopathy
  • Endocarditis
  • Myocarditis
  • Lyme disease
  • Hyperthyroidism
  • High potassium levels
  • Older age
  • Coronary artery disease
  • Sarcoidosis

The possible complications involved in Heart Block are:

  • Bradycardia
  • Arrhythmia
  • Cardiac arrest 
  • Circulatory failure
  • Low heart rate

Heart Block can be prevented by following a healthy lifestyle as it helps in maintaining the overall health of the body. Eating a healthy diet and exercising can assist in maintaining good health.

There are three types of heart blocks, First-degree heart block, Second-degree heart block, and Third-degree heart block. 

A patient with a heart block can do mild exercises like swimming, cycling, jogging, etc. for two and a half-hour in a week if the patient has no other heart-related issues. 


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