Heart Block: Symptoms, Causes, Treatment

What are the symptoms of a heart block?

A heart block, also known as atrioventricular (AV) block, is a condition in which there is a delay or complete interruption of the electrical signals that control the heartbeat. The symptoms of a heart block can vary depending on the severity of the block and the individual’s overall health. Here are some common symptoms of a heart block:

Mild (First-degree AV block):

• None or mild symptoms, such as:
  • No palpitations or irregular heartbeats
  • Normal heart rate
  • No shortness of breath
  • No chest pain

Moderate (Second-degree AV block):

• Symptoms may include:
  • Irregular heartbeat (arrhythmia)
  • Palpitations
  • Shortness of breath
  • Chest pain or discomfort
  • Fatigue
  • Dizziness or lightheadedness
  • Fainting or near-fainting spells

Severe (Third-degree AV block):

• Symptoms are often more severe and may include:
  • Rapid and irregular heartbeat (ventricular tachycardia)
  • Palpitations
  • Shortness of breath
  • Chest pain or discomfort
  • Confusion
  • Loss of consciousness (syncope)
  • Cardiac arrest

Other symptoms that may occur in people with a heart block include:

• Exercise intolerance
• Difficulty exercising or engaging in physical activities
• Fatigue
• Weakness or swelling in the legs, ankles, or feet (due to decreased blood flow)
• Decreased urine output or dark-colored urine (due to decreased blood flow to the kidneys)

It’s essential to seek medical attention if you experience any of these symptoms, especially if they are severe, sudden, or persistent. A healthcare provider will perform tests to diagnose and treat a heart block accordingly.

What are the causes of a heart block?

A heart block, also known as atrioventricular (AV) block, is a condition where there is a delay or complete interruption of the electrical signals that control the heartbeat. The causes of a heart block can vary, and it may be classified into different types based on the location and severity of the blockage. Here are some common causes of a heart block:

Congenital heart block:

• Present at birth, often due to a defect in the development of the heart’s electrical system

Acquired heart block:

• Develops over time due to various factors, such as:
  • Age-related degeneration of the heart’s electrical system (common in older adults)
  • Inflammation or infection (e.g., rheumatic fever, viral infections)
  • Heart attack or myocardial infarction
  • Cardiomyopathy (disease of the heart muscle)
  • Valve disease (e.g., mitral valve disease)
  • Surgery or cardiac catheterization procedures

Specific conditions that can cause a heart block:

• Wolff-Parkinson-White syndrome: A congenital condition characterized by an extra electrical pathway in the heart that can cause irregular heartbeat and heart block.
• Lyme disease: An infectious disease caused by a tick bite that can affect the heart’s electrical system.
• Sarcoidosis: An inflammatory disease that can affect various organs, including the heart, and cause cardiac arrhythmias and heart block.
• Amyloidosis: A condition where abnormal proteins build up in tissues, including the heart, which can disrupt normal electrical function.
• Medications: Certain medications, such as beta blockers, calcium channel blockers, and certain antidepressants, can cause a heart block as a side effect.

Other factors that may contribute to a heart block:

• Age: The risk of developing a heart block increases with age.
• Family history: A family history of cardiac arrhythmias or heart block can increase the risk.
• Weakened or damaged heart muscle: Conditions like cardiomyopathy or myocardial infarction can increase the risk of developing a heart block.

It’s essential to note that some cases of heart block may be idiopathic, meaning that no specific cause is identified. If you experience symptoms of a heart block, it’s crucial to seek medical attention to determine the underlying cause and receive appropriate treatment.

How is the diagnosis of a heart block made?

The diagnosis of a heart block, also known as atrioventricular (AV) block, typically involves a combination of physical examination, medical history, and diagnostic tests. Here are the steps involved in diagnosing a heart block:

Physical Examination:

• The doctor will perform a physical examination to check for signs of heart failure, such as swollen legs, ankles, or feet, and listen to the heart sounds using a stethoscope.
• The doctor may also check for other signs of cardiac disease, such as murmurs or gallops.

Medical History:

• The doctor will ask questions about the patient’s medical history, including:
  • Previous heart problems or surgeries
  • Family history of cardiac arrhythmias or heart block
  • Medications currently being taken
  • Symptoms experienced, such as dizziness, lightheadedness, or shortness of breath

Electrocardiogram (ECG):

• A 12-lead ECG is the most common diagnostic test for a heart block. It measures the electrical activity of the heart and can help diagnose the type and severity of the block.
• An ECG can detect:
  • P-waves (atrial activity)
  • QRS complexes (ventricular activity)
  • T-waves (ventricular repolarization)
  • PR interval (the time it takes for the electrical signal to travel from the atria to the ventricles)

Other diagnostic tests:

• Holter monitor: A Holter monitor is a portable device that records the heart’s rhythm over 24-48 hours. It can help diagnose abnormal heart rhythms and identify periods of heart block.
• Event monitor: An event monitor is similar to a Holter monitor but is used to record specific symptoms or events, such as palpitations or dizziness.
• Echocardiogram: An echocardiogram uses sound waves to create images of the heart. It can help evaluate cardiac function and identify any structural abnormalities.
• Cardiac catheterization: In some cases, a cardiac catheterization may be performed to evaluate coronary artery disease or valve function.
• Stress test: A stress test may be performed to assess the heart’s ability to respond to exercise.

Diagnostic criteria:

• The American Heart Association and the American College of Cardiology have established criteria for diagnosing AV block:
  • First-degree AV block: Prolongation of the PR interval (>200 ms) without other evidence of AV nodal dysfunction.
  • Second-degree AV block: Prolongation of the PR interval (>200 ms) with intermittent failure of impulse conduction.
  • Third-degree AV block: Complete absence of conduction between the atria and ventricles.

A healthcare provider will consider all these factors to diagnose and classify a heart block. If you suspect you have a heart block or are experiencing symptoms, it’s essential to consult with a healthcare provider for an accurate diagnosis and appropriate treatment.

What is the treatment for a heart block?

The treatment for a heart block, also known as atrioventricular (AV) block, depends on the type and severity of the block, as well as the individual’s overall health and other medical conditions. Here are some common treatments for heart block:

Mild heart block (First-degree AV block):

• No specific treatment is usually needed, as the condition is often asymptomatic.
• Patients may be monitored with an event monitor or Holter monitor to track the heart’s rhythm.
• If symptoms occur, treatment may include beta blockers to slow the heart rate.

Moderate heart block (Second-degree AV block):

• Medications:
  • Beta blockers to slow the heart rate and reduce symptoms.
  • Anti-arrhythmic medications to regulate the heartbeat.
  • Calcium channel blockers to relax blood vessels and reduce blood pressure.
• Pacemakers or implantable cardioverter-defibrillators (ICDs) may be considered for patients with frequent or prolonged episodes of second-degree AV block.
• Surgery: In rare cases, surgery may be necessary to repair or replace damaged heart valves.

Severe heart block (Third-degree AV block):

• Emergency treatment:
  • Cardiac pacing: Temporary or permanent pacemakers are used to regulate the heartbeat.
  • ICDs: Implantable devices that can detect and correct abnormal heart rhythms.
• Medications:
  • Anti-arrhythmic medications to regulate the heartbeat.
  • Beta blockers to slow the heart rate.
• Surgery: In severe cases, surgery may be necessary to repair or replace damaged heart valves or restore normal conduction.

Other treatments:

• Cardiac resynchronization therapy (CRT): For patients with left bundle branch block (LBBB) and systolic heart failure, CRT can help synchronize the heartbeat and improve symptoms.
• Biventricular pacing: A type of cardiac pacing that involves placing electrodes in both ventricles to improve synchronization of the heartbeat.

Lifestyle changes:

• Patients with a heart block should avoid strenuous activities that can exacerbate symptoms.
• Regular exercise, such as walking, is recommended to improve overall cardiovascular health.
• Quitting smoking, reducing stress, and managing high blood pressure and cholesterol levels can help reduce the risk of developing a heart block.

It’s essential to work closely with a healthcare provider to determine the best course of treatment for a heart block. They will consider your individual situation, medical history, and other health factors when developing a treatment plan.