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Complete Heart Block or Third-Degree Atrioventricular (AV) Block

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Third-degree atrioventricular (AV) block, also commonly known as third-degree heart block or complete heart block (CHB), is an irregular heart rhythm that emerges because of a deformity in the cardiovascular conduction system in which there is an absence of conduction through atrioventricular node (AVN), prompting a lack of association between the atria and ventricles.

The ventricular escape component can happen in anyplace from the AVN to the Purkinje cells. The third degree or complete heart blocks happens when the electrical stimulus can’t pass typically from the atria, which are also known as the heart’s upper chambers, to the lower chambers or the ventricles.

On the off chance that the atrioventricular (AV) node is harmed, this may require a medical procedure, third-degree or complete heart block. Sometimes complete heart block happens without any warning signs and requires an immediate medical procedure or bypass surgery. To restore the normal heart rhythm, a pacemaker may come to the rescue.


Each time your heart thumps, an electrical signal makes a trip from the upper to the lower chambers. En route, the signal gestures your heart to contract and pump the blood out. At the point when that signal is backed off or kept from transmitting its message, it results in a condition called heart block. This influences the rhythm and the rate of your heart, the number of times it pulsates and the pattern of the pulsations.

On the off chance that you have heart block that is not congenital or you weren’t born with, the doctor refers it as “acquired” heart blocks.

Acquired heart blocks are the most widely recognized sort and can result from:

  • Certain kinds of medical procedures that influence the heart’s electrical framework
  • Changes in your genetic patterns
  • Damage occurred due to heart attack
  • Heart issues like blocked arteries, irritation of the heart muscle, and heart failure, heartburn
  • Muscle issues or different illnesses
  • Side effects of medicines

On the off chance that drug is the reason, change in the dosage or solution and switching prescriptions could address the issue.

Degrees of Heart Block

Doctors can group heart blocks into classes based on how extreme it is.

  • First Degree Heart Blocks 

This is the soft type of heart block; the heart’s electrical signal is impeded, but it is still moving, which you may not notice.

  • Second Degree Heart Blocks

If a portion of the signals doesn’t reach the correct places, this implies your heart may not pulsate as frequently or as routinely as it is supposed to.

  • Third Degree Heart Blocks (also called complete blocks)

At this stage no electrical signal gets through, the rhythm and rate of your pulse are moderate or it might even stop altogether. This type of heart block can also prove to be deadly.


When the heart starts pulsating abnormally it indicates there is a change in either the speed or the pattern of your heartbeat — the heart may pulsate too quickly, too slowly or sporadically. During this time, the heart also pulsates very slowly, where little blood is siphoned to the entire body. And when the heart pumps too rapidly, it can’t fill totally so the body doesn’t get the blood volume it needs to work appropriately. Low rates of pulses are called bradycardias. Quick heart pulses are called ventricular tachycardia.

The heart is comprised of four chambers. The upper chambers are called atria and are responsible for receiving and collecting blood. The lower chambers are called the ventricles and are responsible for pumping the blood out to the body. Cooperating together, both the chambers of heart circulate life-sustaining blood throughout the body.

A heart that pulsates too rapidly or too slowly can cause:

  • Lightheadedness or dizziness
  • Palpitations (skipping, rippling or pounding in the chest)
  • Fatigue
  • Atrial flutter
  • Chest pain
  • Shortness of breath
  • Fainting spells

Sometimes there may not be any manifestation of any of these symptoms. If left untreated, certain irregular heart rhythms can be life-threatening. Then again, a few arrhythmias are normal and not related to any untoward conditions, purported as benign arrhythmias. One of the objectives of assessment is to separate the serious from the innocuous type of heartbeat disturbances.

Risk Factors

The most widely recognized reason for heart block is scarring of the heart tissue as individuals grow old. A few people are congenial to this condition. However, people with a history of heart disease and frequent smokers are at high risk.

The conditions mentioned below can increase the hazards of heart blocks:

  • Cardiomyopathy
  • Coronary thrombosis
  • Myocarditis, or inflammation of the muscles in the heart
  • Endocarditis, or inflammation of the heart valves
  • Scar tissue in the heart, following any medical procedure or a heart assault.

Intense, or sudden, heart blocks may happen after a heart attack or after any heart surgery. It can also happen as a complication of Lyme infection.


During diagnosis, the doctor will discuss the entire issue with the patient and will also analyze their heart rhythm and heartbeat. Considering their age and medical condition the specialist may speculate coronary illness and can refer the patient to a cardiologist, or a heart valve surgery

There are various indicative tests which are taken when there is a heart block.

An electrocardiogram (ECG) is the most widely recognized test. It records the activity of the heart. Tests put on the skin of the chest demonstrates the electric impulses through the heart as a pattern of waves.

Any irregularities in the wave may show heart block. An ECG can likewise uncover whether the left or right branch is affected.

Holter tape is a compact gadget which records the patient’s pulse all through 24 hours. The patient needs to wear it under their clothes, and it records data about the electrical movement of the heart while the individual can carry out their typical activities for 1 to 2 days.

At the point when symptoms occur, the patient needs to press a button. This makes a record of the heart rhythms available there.

An echocardiogram is an ultrasound test that enables the specialist to see the heart muscles and valves.

An electrophysiology test utilizes modest electrical shocks to decide the reason for the unusual rhythm, and where it is happening in the heart.

In a tilt-table test, the patient needs to lie on a bed that changes position. This can incite arrhythmia or irregular heart pulses.


Pregnant women who have autoimmune disorders may be able to get treatment to decrease the hazard for heart blocks in their babies.

Prevention of heart blocks only revolves around predominantly on dealing with the risk factors. Adopting a healthy lifestyle helps in your overall wellbeing and it also helps improve your heart’s health. Exercising and maintaining a balanced diet and avoiding smoking all eventually contribute to the betterment of your health and heart. Understanding the hazards of your medications and taking the advice of your medical practitioner can help you stay away from medicine induced heart blocks. Consult with your medical practitioner before taking any herbal supplements or medicines, particularly on the off chance you are already prone for heart blocks.


There is no specific treatment for heart-block. Some people having a bundle branch block have no visible symptoms, and they don’t need any treatment. But in the presence of any underlying medical condition such as hypertension, treatment may become necessary.

On the off chance that an individual with left bundle branch blocks suffers heart attacks, reperfusion therapy treatment can be given to reestablish blood flow through the blocked arteries.

This should be possible by utilizing an anti-clogging agent, for example, streptokinase, to break up blood clusters and increase blood flow to the heart. However, these drugs may increase the hazards of bleeding.

An artificial pacemaker, a little, battery-worked gadget, might be embedded under the skin in a patient with a past history of fainting. It is put close to the collarbone during the surgery lasting for 1 to 2 hours, under local anesthetic.

Pacemakers can be set to create an electrical impulse only when required. Some can detect if the heart stops pulsating, and create an electrical impulse to restart the same. The duration of the battery can be for many years.

Pacemakers are not influenced by mobile phones, individual stereos, or other appliances, however, an individual with a pacemaker are advised not to undergo a (MRI) Magnetic resonance imaging scan. There are MRI friendly pacemakers too.


Individuals with a left side bundle branch block have a higher degree of complications compared to people with a right side block.

Some possible complications include:

  • Experiencing arrhythmia, or sporadic heartbeat
  • bradycardia, or low heart pulse
  • Insufficient contraction
  • Cardiac and circulatory failure
  • Sudden cardiovascular complications, which can be deadly

Heart block cannot be avoided always, however, the danger of coronary illness can be reduced by disciplined eating with a heart-healthy diet, a regular exercise regimen, avoiding alcohol intake and staying tobacco-free.

Verified By Apollo Cardiologist

The content is reviewed and verified by our experienced and highly specialized team of heart specialists who diagnose and treat more than 200 simple-to-complex heart conditions. These specialists dedicate a portion of their clinical time to deliver trustworthy and medically accurate content

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