What is Heart Block?
Heart Block (AV Block) is a type of arrhythmia in which the electrical conduction between the upper and lower chambers of the heart slows down or completely stops. This disruption can cause the heart to beat slower than normal or irregularly. The severity of heart block varies depending on its degree, leading to different symptoms and associated risks.
This conduction disturbance can sometimes be temporary, but it can also become permanent and lead to serious arrhythmias. Especially in cases of advanced heart block, close monitoring and appropriate treatment are crucial. Treatment options include medication and the implantation of a pacemaker.
In addition to AV Block, there is also a condition called SA (Sinoatrial) Block. SA block occurs when there is an issue with the propagation of the initial electrical signal from the sinoatrial node to the atria. SA block can sometimes lead to serious heart stoppages.
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What are the Types of Heart Block?
Heart block is classified into three main types based on the degree of disruption in electrical conduction. Each type has its own characteristics and risk levels. Depending on how much the electrical signals are blocked, heart block is divided into first, second, and third-degree blocks.
First degree AV Block
The mildest form of heart block, first-degree AV block occurs when electrical signals pass through the AV node, but the conduction is delayed. This means the heart rate is slower than normal, but each signal still reaches the ventricles. Typically, this condition does not cause significant symptoms and often does not require treatment.
Second degree AV Block
Second-degree heart block is more serious than first-degree and involves partial blockage of the electrical signals. This type of block is further divided into two types: Second-degree type I and second-degree type II.
- Type I AV block: In this type, electrical signals passing through the AV node progressively slow down until eventually, one signal fails to reach the ventricles. This is usually a temporary and mild condition.
- Type II AV block: In this type, signals are intermittently blocked, but the rhythm can suddenly return to normal. Type II AV block is generally more dangerous and can carry the risk of heart stoppage.
People with second-degree block may experience the following symptoms:
- Fainting, dizziness, or feeling light-headed
- Feeling fatigued
- Shortness of breath
- Chest pain
- In some cases, no symptoms may occur.
Third degree AV Block (Complete Heart Block)
Third-degree AV block, or complete AV block, is the most serious type of heart block. In this condition, the electrical signals are completely blocked. The signals from the atria cannot reach the ventricles, and the heart continues to beat at its own slow pace. The heart rate is typically very low. Most people with third-degree heart block experience symptoms. The symptoms may be similar to those of second-degree block but tend to be more severe. Third-degree heart block can be life-threatening.
What are the Symptoms of Heart Block?
Heart block symptoms vary depending on the type and severity of the block. While some people may not notice any symptoms, others may experience:
- Feeling dizzy or lightheaded
- Fainting spells
- Feeling your heart racing or skipping beats
- Feeling unusually tired
- Finding it hard to breathe
- Chest pain or discomfort
- Slow or irregular heartbeat
What Causes Heart Block?
Heart block occurs when the electrical signals are delayed or completely blocked from passing through the AV node. The main causes of heart block include:
- Degeneration of the conduction system: With age, the heart’s electrical conduction system may weaken, causing a delay or blockage in signal transmission.
- Cardiac procedures or surgeries: Heart surgery or other cardiological interventions can affect electrical conduction and lead to blockages.
- Medications: Certain medications, especially those used to regulate heart rhythm, may cause heart block.
- Aortic valve infections: Infections of the aortic valve can impact the heart’s electrical system and lead to blockages.
- Congenital factors: Although rare, some individuals are born with heart block, often due to genetic factors.
How is an Heart Block Diagnosed?
The diagnosis and type of heart block are typically determined using an ECG or rhythm Holter monitoring. These tests record the heart’s electrical activity and can show the degree and characteristics of the block.
An ECG (Electrocardiogram) provides an instant snapshot of the heart’s electrical activity. Electrodes placed on the skin record the heart’s electrical signals. The ECG can detect the presence and degree of the block by evaluating the transmission time and pattern between the atria and ventricles.
A Holter monitor is a portable device that continuously records the heart rhythm for 24 to 48 hours. It is especially useful for detecting intermittent blocks or conduction issues that vary throughout the day. Holter monitoring provides a more detailed evaluation by documenting the frequency, duration, and relationship of the block with daily activities.
How is an Heart Block Treated?
The treatment of heart block depends on its degree. Most people with first-degree heart block do not require treatment. Some individuals with second-degree type I block may need a pacemaker. Most people with second-degree type II or third-degree heart block (unless it’s congenital) require a pacemaker.
Another important aspect of treatment is identifying and addressing any underlying conditions that are causing the heart block. For example, certain medications can cause heart block, in which case discontinuing or changing the medication may be necessary. Similarly, imbalances in electrolytes or infections in the body can lead to heart block and should be treated accordingly.
What are the Complications of Heart Block?
Untreated heart block can lead to serious complications. Especially in the case of complete block, the heart may not be able to pump enough blood to the body, increasing the risk of organ damage, fainting, and sudden cardiac arrest.
FAQs About Heart Block
Can Someone with Heart Block Travel by Air?
Most patients can travel by air, but those with advanced blocks, especially those with pacemakers, should seek medical advice before flying.
Do Heart Block Symptoms Appear Suddenly?
Symptoms can appear suddenly or gradually depending on the type and cause of the block. Sudden-onset symptoms are usually more serious and require immediate intervention.
What Precautions Should Be Taken After Pacemaker Implantation?
Patients with pacemakers should avoid strong magnetic fields and attend regular pacemaker check-ups. Additionally, certain devices or technological equipment may affect pacemaker function, so medical advice is important.
Is the Situation Different for Children with Heart Block?
Congenital heart blocks can occur in children and are usually diagnosed earlier. Treatment and monitoring methods may differ from adults.
Can Someone with Heart Block Lead a Normal Life?
Yes, most patients can lead a normal life with appropriate treatment and monitoring.
Can Heart Block Be Prevented?
Some cases cannot be prevented, but a healthy lifestyle, regular check-ups, and maintaining heart health can reduce the risk.
Is Heart Block Genetic?
Some rare forms can be genetic, but most heart blocks are acquired.
Does Exercise Affect Heart Block?
The effects of exercise vary depending on the individual and the type of block. Exercise programs should be planned under medical supervision.
Is It Safe for Someone with Heart Block to Get Pregnant?
Many women can safely become pregnant, but close medical supervision is required.
Reference: Atrioventricular Block