What is a Complete Heart Block [Third-degree Atrioventricular (AV) Block]?

Heart Block Overview

Heart block also called atrioventricular (AV) block refers to an issue with the heart’s electrical system. This happens when the heart beats irregularly and very slowly. It may stop for about 20 seconds at a time. This can be due to an obstruction or delay along the path through which the electrical impulses travel. This condition can occur due to any damage or an injury to the heart valves or the heart muscle. Since the heart blocks itself, it does not usually need treatment. However, the underlying related health condition does.

Generally, heart block leads to palpitations, fainting, and lightheadedness. Some may even witness chest pain. Depending on its intensity, heart block may be quite dangerous. For instance, a complete heart block (third-degree heart block) can worsen pre-existing conditions. It may result in unconsciousness or even sudden cardiac arrest.

What is Heart Block?

A heart block is a condition that disrupts the heart’s electrical impulses. Generally, a resting heart rate ranges from 60 to 100 beats per minute. With each heartbeat, the heart muscle contract and pushes blood around our body. Usually, heart muscle contractions are regulated by electrical impulses that travel from the heart’s upper chambers or the atria to the lower chambers or the ventricles.

A partial heart block can be caused when the electrical impulses are delayed or stopped partially. This prevents the heart to pump blood at regular intervals. On the other hand, a complete heart block refers to a condition when the electrical signals are disrupted or stopped entirely. This may lead to a drop in heartbeat to around 40 times a minute. Also, it must be noted that even changes to impulses that last for just a fraction of a second can result in heart block.

Sometimes, a heart block makes it difficult for the heart to pump blood through the circulatory system. This leads to a reduced supply of oxygen to the muscles and organs (including the brain). This may result in impairing their functions.

Types of Heart Block

Heart block is of three types, namely:

First-degree heart block: It refers to minor heartbeat disturbances and can often cause skipped heartbeats. First-degree heart block is not very serious and usually does not require treatment.

Second-degree heart block: This can happen when some electrical signals are unable to reach the heart. This can cause skipped or dropped heartbeats. Since the atrial impulse does not reach the ventricles, it may not contract. The patient may feel dizzy and in some cases, may also require a pacemaker.

Complete heart block or third-degree heart block: A complete heart block is caused when the electrical signals are unable to travel between the lower and upper chambers of the heart. This condition is quite common among heart patients. This may be caused by damage to the atrioventricular node (AV node) during surgery. However, at times, it may also occur naturally. To re-establish a normal heart rhythm or rate, an artificial pacemaker is required. Without a pacemaker, people who are diagnosed with complete heart block are at a higher risk of a heart attack.

Symptoms of  Heart Block

Some of the signs and symptoms that are witnessed in case of a complete heart block are:

• Chest pain
• Palpitations (feeling of fluttering, pounding or skipping in the chest)
• Pre-syncope (feeling of dizziness or faintness)
• Breathlessness
• Fatigue or extreme tiredness
• Syncope (fainting)
• Slow heartbeat (bradycardia)

These signs and symptoms can often be life-threatening. One should call for an ambulance or call their local medical emergency service provider if they experience such symptoms.

Causes of  Heart Block

The majority of people who are diagnosed with complete heart block are already suffering from an underlying heart condition. This may include conditions like congenital heart disease, cardiomyopathy, or coronary heart disease. Age can also be a cause since electrical pathways in the heart ages as well. Few medications and electrolyte imbalances can also lead to complete heart block.

Diagnosis  of  Heart Block

An individual would be advised to visit a heart specialist (cardiologist) to get a complete cardiac evaluation. The cardiologist would require the patient’s past medical records. This would also include records of any heart tests that the patient would have undergone.

The doctor may also ask a few questions about the patient’s general health, diet, activity levels, and also their family medical history. Other than this, they would also ask whether the individual is one any over-the-counter or prescription medicine. They would also want to know whether the patient consumes alcohol, drugs, or smokes.

The patient will then go through a comprehensive physical examination to check the pulse and measure the heart rate or heart rhythm. The specialist may also check for symptoms of heart failure like fluid retention in the feet or legs.

Heart block is diagnosed through Electrocardiogram (ECG or EKG). ECG is used to record the heart’s electrical activity. It creates a graph demonstrating the heart rhythm and heart rate which also includes the timing of electrical signals as they move through the heart.

If the doctor would require to check electrical signals over a long period, the patient would be recommended to wear a Holter Monitor. This is a small, portable ECG machine for cardiac monitoring for at least 24 to 72 hours. This can help in detecting problems that may not get highlighted on a resting ECG.

Treatment of  Heart Block

Complete heart block can be life-threatening. Thus, the specialist may recommend medication or even implanting a pacemaker, depending on the severity.

Medicines

The patient might also be prescribed some anti-arrhythmic medications. This can alter the electrical signals in the heart and even prevent disturbances in the electrical system of the heart.

Pacemaker

Implanting a pacemaker involves minor surgery. The device has two wires that connect to the heart’s right side. It works as a backup electrical system for the heart that reminds the heart to beat at a normal rate if it stops or slows down.

Complete heart block is a serious medical issue. Thus, proper diagnosis and treatment are extremely important. Also, one should only consult a highly-skilled and experienced heart specialist to ensure proper treatment of the condition.

Knowing the symptoms and making lifestyle changes can definitely help. Take action now! Enrol in our comprehensive Healthy Heart Program to keep your heart healthy.