Introduction: When the Signal Gets Stuck
Your heart doesn’t just beat. It communicates. An electrical signal starting the process sets up a systematic pathway that orders the heart to contract and push blood out. However, sometimes the signal does not transfer properly across the heart. When the signal is interrupted as it travels from the atria to the ventricles, it is called an atrioventricular block (AV block).
In simpler terms? An AV block means there is a hold or shutdown of the electrical signal telling the heart to contract. Based on how bad the block is, it might not do any harm or could cause serious problems.
So let’s break it down. What is AV block? How does it affect your heart? And why does it matter?
First, a Quick Recap of How the Heart Beats
We have to understand how your heart’s electrical system works to begin learning about AV block.
The heart’s pacemaker, the sinoatrial (SA) node, is found in the right atrium and sets off every heartbeat. The SA node causes an electrical pulse that makes the atria pump blood into the ventricles.
After that, the impulse goes to the atrioventricular (AV) node, located in between the atria and the ventricles. The AV node stops and pauses the heartbeat for a moment to allow blood to enter the ventricles. This leads the signal to the His bundle which then gives a command to the Purkinje fibers to make the ventricles contract and push blood into the body.
If all systems are in balance, your heart maintains a normal beat. If the AV node is prevented from passing the signal due to a delay, distortion or stop, you will get an AV block.
So, What Is an AV Block?
When someone has an atrioventricular block, it is most affected by a problem in the way electrical signals move between the atria and ventricles in their heart.
It ends up like a message that somehow never reaches the recipient. The result? You might experience a slow, uneven or skipped heartbeat.
Usually, AV (atrioventricular) block is classified into three degrees depending on the level of disruption.
First-Degree AV Block: A Minor Delay
This is the mildest form.
When there is first-degree AV block, it slows down the signal from the atria to the ventricles, but it continues to pass. You might not even feel any symptoms. The condition shows as a PR interval that lasts longer than it should, though your heart rate remains regular.
Common causes:
- Aging
- Medications (like beta blockers or calcium channel blockers)
- Heart inflammation
Symptoms:
- Usually none
- Sometimes fatigue or lightheadedness
First-degree AV block is often not a big concern and usually does not need treatment. The doctor may watch your calcium level when you are taking heart medicines, even if you do not have medical concerns.
Second-Degree AV Block: Some Signals Get Dropped
Now things get more serious. During second-degree AV block, some of the signals going to the ventricles get blocked. This can lead to dropped or skipped heartbeats.
There are two types:
Type I (Mobitz Type I or Wenckebach)
- It keeps getting slower until it misses one whole beat.
- Then the cycle repeats.
- Often seen in athletes or during sleep.
Symptoms:
- Dizziness
- Fatigue
- Feeling like your heart skips a beat
Many times this type requires no treatment, but it should still be watched.
Type II (Mobitz Type II)
- The AV node suddenly blocks a signal without warning.
- The pattern is less predictable—and more dangerous.
Symptoms:
- Chest pain
- Fainting (syncope)
- Difficulty exercising
This type often requires a pacemaker. Why? Since the threat of a sudden block becomes greater due to the unpredictability.
Third-Degree AV Block: The Complete Disconnect
It is often called complete heart block which is the most serious type. This type of block prevents any Of the atrial electrical signals from moving to the ventricles. So, the ventricles turn to a backup pacemaker located in the heart which gives them a slower, irregular beat.
They’re like two musicians who are trying to play without a conductor—they are totally off beat.
Symptoms:
- Severe fatigue
- Fainting
- Shortness of breath
- Confusion
- Risk of cardiac arrest
It is considered a medical emergency and usually a permanent pacemaker must be put in to correct the irregular heart rhythm.
What Causes AV Block?
AV block may be there at birth or start developing later in life. Common causes include:
- Changes in the heart’s functions are typical with aging.
- Heart disease: Especially coronary artery disease or heart attacks
- Sometimes, procedures done near the heart or ablation may harm the AV node.
- Autoimmune diseases: Like lupus or sarcoidosis
- Infections such as Lyme disease or a viral infection might block the heart for a short period
- Some heart conditions can be managed by medicines like digoxin, beta blockers, calcium channel blockers and antiarrhythmics which slow down how quickly impulses travel in the heart
In some cases, there is no definite explanation for the symptoms—although this is something that happens quite often.
How Is AV Block Diagnosed?
People may experience fainting, dizziness, tiredness or a slow rate of pulse at first. Still, people who discover these conditions are often surprised: it’s discovered while performing an ordinary ECG or with a Holter monitor.
Common tests include:
Spotting AV block is best done through an electrocardiogram (ECG).
Holter monitor: A device you wear for 24 to 48 hours to monitor your heart rhythm.
Event monitor: For keeping an eye on your symptoms when their appearance is rare.
Electrophysiology study is sometimes used to pinpoint where the intrinsic imaging mapping (i) defect happens.
What Are the Treatment Options?
How much of your airway is blocked and how noticeable your symptoms are guides the treatment.
For First-Degree and Type I Second-Degree AV Block:
Usually, no treatment is needed.
Your doctor may adjust medications or monitor you regularly.
For Type II Second-Degree and Third-Degree AV Block:
- These usually require a pacemaker.
- A pacemaker helps by sending signals to your heart to maintain a regular rhythm.
- Until a permanent pacemaker can be placed, you might use a temporary pacemaker during an emergency.
The good news? Pacemakers function well with no fuss, usually restoring effectiveness, mental sharpness and inner confidence in daily life.
Living with AV Block
With mild AV block, you might not have to do much differently. Just keep up with checkups.
You’ll be expected to have follow-up visits if you have a pacemaker to make sure everything is fine. However, the majority of survivors return to active lives that are just like before their trauma. You are allowed to fly, exercise when advised and go through airport security, but tell TSA you have a pacemaker.
Remember: managing heart health is a team effort. Keep to your care plan, take the medications instructed by your doctor and pay attention to how your body feels.
Final Thoughts: When Communication Breaks Down, Backup Is Essential
Atrioventricular block is mainly a problem where one chamber of the heart does not receive information from another chamber. That said, when the cause is understood and a solution like a pacemaker can help—just like any communication challenge—things run smoothly again.
Both mild and severe cases of AV block can be treated with successful resolutions. Early detection is key. Don’t brush off symptoms like fatigue or fainting. Sometimes such sensations can be your heart trying to warn you about something.