Heart Block

Heart block, also known as atrioventricular (AV) block, is a medical condition that affects the electrical conduction system of the heart. It occurs when there is a delay or interruption in the electrical signals that control the heartbeat, causing the heart to beat too slowly or irregularly.

Types of Heart Block

• First-degree heart block (1° AV block): This is the mildest form of heart block, where the electrical signal from the atria to the ventricles is delayed, but all signals are still conducted.
• Second-degree heart block (2° AV block): This type of heart block is further divided into two subtypes:
  • Mobitz Type I (Wenckebach): The delay in electrical signal conduction increases with each heartbeat, until a beat is finally dropped.
  • Mobitz Type II: Some electrical signals are not conducted to the ventricles, resulting in dropped beats.
• Third-degree heart block (3° AV block): This is the most severe form of heart block, where no electrical signals are conducted from the atria to the ventricles, and the ventricles beat independently of the atria.

Causes of Heart Block

Heart block can be caused by a variety of factors, including:

• Age-related wear and tear on the heart's electrical conduction system
• Coronary artery disease or heart attack
• Cardiomyopathy (diseases of the heart muscle)
• Infections, such as Lyme disease or endocarditis
• Certain medications, such as beta blockers or calcium channel blockers
• Genetic conditions, such as muscular dystrophy

Symptoms of Heart Block

The symptoms of heart block can vary depending on the severity and type of block. Common symptoms include:

• Fainting or near-fainting (syncope)
• Dizziness or lightheadedness
• Shortness of breath
• Chest pain or discomfort
• Fatigue or weakness
• Palpitations or irregular heartbeat

Diagnosis of Heart Block

Heart block is typically diagnosed using:

• Electrocardiogram (ECG or EKG): A test that measures the electrical activity of the heart.
• Holter monitor: A portable device that records the heart's electrical activity over a 24-hour period.
• Event monitor: A device that records the heart's electrical activity over a longer period, typically 30 days.
• Echocardiogram: An ultrasound test that evaluates the heart's structure and function.

Treatment of Heart Block

The treatment for heart block depends on the severity and type of block. Common treatments include:

• Pacemaker implantation: A small device that is implanted under the skin to regulate the heartbeat.
• Medications: To control symptoms, such as beta blockers or anti-arrhythmic medications.
• Lifestyle modifications: Such as avoiding strenuous exercise or managing underlying medical conditions.