The heartbeat is controlled by electrical signals (impulses), which instruct your heart to contract. Normally, a heartbeat occurs when the SA node (sinoatrial node) generates an electrical signal in the atria (upper chamber of the heart) which then moves to the ventricles (lower chamber of the heart) via the atrioventricular (AV) node. The ventricles thus contract and pump blood to the rest of your body. A heart block occurs when there is an interference in allowing the electric signals to move from the atria to the ventricles.

Complete heart block or third degree heart AV block occurs when the electrical signal cannot move from the atria to the ventricles i.e. it stops completely. This causes the heartbeat to drop to as low as 40 beats per minute as against the normal beat which is 60 to 100 beats per minute (bpm), for an adult. Often, this condition is found to be very common for people suffering from heart diseases.

In such cases, a natural back-up system in the ventricles takes over, but the heart rhythm is much slower and more irregular than normal.

Signs and Symptoms

You may experience the following:

  • Irregular heartbeats, or palpitations
  • Trouble in breathing or shortness of breath
  • Excessive fatigue
  • Light-headedness and fainting
  • Angina or discomfort in the chest
  • Cardiac arrest

If a heart block is ignored and not treated will lead to internal organ injury or cardiac arrest.


If your doctor suspects that you having irregular heartbeats, then:

  • Your overall health condition and medical history will be reviewed.
  • Your family history of heart disease will be checked.
  • Your current medication will be reviewed, to check for any medicine induced heart block.
  • Your lifestyle will be discussed (like alcohol, smoking, drugs etc.)
  • An ECG (electrocardiogram) will be done to determine the pattern of heart’s electrical impulses and to diagnose arrhythmias and heart damage.
  • Holter monitor, a portable device that you will wear for around 24 hours will record the ECG as you carry out your daily routine. Holter monitor detects arrhythmias which is often missed by ECG due to resting position.
  • A stress test, sometimes called a treadmill test or exercise test is recommended to measure the heart’s ability to respond under stress but in a controlled clinical environment.
  • Head up tilt table test, is performed to monitor and record your blood pressure, heart rate (on beat-by-beat basis) and heart rhythm as the table is tilted in different angles.
  • Cardiac MRI, is a non-invasive technique recommended to capture images inside your heart. It helps your doctor to detect heart diseases like blockage, structural problem, damage to heart muscles etc.
  • An electrophysiology study is performed to know more accurate and detailed information about your heart’s electrical system like, nature of abnormal heart rhythms, to know from where the abnormal heartbeat is coming from etc.


If you are diagnosed with a third degree heart block, your cardiologist will recommend a pacemaker, unless the problem can be managed by stopping the medication that may have caused the heart block.

A Pacemaker is a small device which is implanted under the skin in your chest. The pacemaker is like an electrical system which uses electrical pulses to keep your heart beating normally.

Life after heart block

Life after heart block with a pacemaker is definitely better than before. You can lead an active life by following the measures listed below:

  • After some types of pacemaker implantation, you cannot undergo MRI scan.
  • During your visit to any doctor due to some other health condition, please mention about your pacemaker implantation.
  • Always carry a card that has the details of pacemaker implanted.
  • Stay active, eat healthy and follow your doctor’s advice.
  • Get your pacemaker checked on routine basis.


Heart block is not always avoidable and complete heart block is the most severe form of heart block. They can worsen your pre-existing health conditions, due to insufficient supply of oxygen. Third degree heart AV block can be congenital or acquired. In case of acquired heart blocks, the risk increases with age, due to existing heart diseases etc. Prevention of heart blocks mainly focuses on the management of risk factors i.e. knowing your medication (to avoid medicine induced heart block), by leading a healthy lifestyle, eating appropriately, regular exercise and consulting your doctor at the onset of first sign of heart block.