Atrioventricular block

AV block: description

The heart beats 60 to 80 times a minute in a phase without physical stress. In the so-called sinus node in the right atrium of the heart, the electrical impulses for the heartbeats are formed. From the sinus node, they are directed via the so-called AV node into the muscle cells of the left and right ventricle. Then the muscle cells contract.

Sometimes the electrical impulses are conducted very slowly from the AV node to the ventricles. Behind the AV node is a so-called block. People over the age of 70 with heart disease are the most affected. There are three types of AV block:

In a first-degree AV block (AV block 1), the transmission of the electrical signal is not interrupted, but significantly delayed. Mostly those affected have no symptoms. The block becomes visible by chance in the ECG (electrocardiogram).

A 2nd degree AV block (AV block 2) is characterized in that not all electrical signals from the atrium reach the chambers. One distinguishes an AV block Wenckebach from an AV block Mobitz. Either, electrical impulses are alternately forwarded or not, or the forwarding is increasingly sluggish until it completely fails. A 2nd degree AV block can also occur in young, healthy people. However, it is often triggered by a heart muscle inflammation or a heart attack.

In a 3rd degree AV block (AV block 3), the transition of the signal from the atrium to the chamber is completely interrupted. The heart muscles, however, are able to generate very slow strokes themselves. The heart then beats at a rate of 20 to 30 beats per minute. About two percent of those over 70 years old suffer an AV block 3. He is very dangerous.

AV block: symptoms

Complaints usually occur only from a 2nd degree AV block. The heartbeat may feel irregular. Many sufferers do not feel as resilient as usual or they are persistently dizzy. Very rarely do they lose consciousness.

In 3rd degree AV block the heart rate drops below 40 beats per minute. Therefore, various organs can only be supplied with blood poorly. When electrical transmission is completely blocked, it sometimes takes some time for the “replacement rhythm” generated by the muscles to start. Through this form of cardiac arrest, the brain is hardly supplied with blood. Partial dizziness or fainting spells occur. At a standstill lasting more than 20 seconds, seizures or respiratory arrest may occur. Therefore, the AV block 3 is a life-threatening event.

AV Block: causes and risk factors

An atrioventricular block usually arises in diseases of the heart such as heart failure, myocarditis, other cardiac arrhythmias and coronary heart disease. Also, rheumatic diseases, tumors or heart valve and bypass surgery can trigger an AV block. Rarely is the arrhythmia innate.

AV block: diagnosis and examination

The doctor first asks what the sufferer has and whether he suffers from other illnesses. This is followed by a physical examination.

In most cases, a so-called electrocardiogram (ECG) is sufficient to diagnose the arrhythmia. With an ECG, the electrical cardiac currents are measured and recorded by a recorder. Sometimes an ECG must be written for a long time to detect the arrhythmia. Since an AV block sometimes occurs only under physical stress, a so-called stress ECG can also be performed. The patient cycles on a kind of “home trainer” while the ECG is being recorded.

A blood test can provide information about the cause of the arrhythmia. If necessary, the heart must be further examined to find the cause of the AV block.

AV block: treatment

An AV block 1 usually requires no therapy. If the patient takes certain medications, they may need to be discontinued.

In AV block 2, regular ECG checks are performed. When patients have discomfort or have become unconscious, a pacemaker usually needs to be implanted. The pacemaker takes over the tasks of the sinus and AV nodes when the heartbeat becomes too slow. In an AV block 3, a pacemaker can be life-saving.

After implantation of a pacemaker, certain factors should be considered. For example, those affected by security checks at the airport must be aware that the function of the pacemaker can be disturbed by the metal detectors. Immediately after implantation, do not lift heavy weights or perform arm movements above the head.

AV block: Disease course and diagnosis

The prognosis differs depending on the degree of the AV block. After implantation of a cardiac pacemaker, there is usually no longer a risk of complications as it protects against slow heart rates. If the AV block is triggered by medication, it often disappears after it has been discontinued. It is possible for an AV block to become 1 or 2 in a higher gradeAtrioventricular block passes.