Diseases

AV Block – Causes, Symptoms & Treatment

AV block

In a healthy heart, the heart rhythm is determined by the sinus node and transmitted to the ventricles via the AV node. In the case of cardiac arrhythmias such as AV block (atrioventricular block) , this stimulus conduction is disturbed.

What is AV block?

An AV block (atrioventricular block) leads to an abnormal heart rhythm , which is relatively common. While the heart beats around 60 to 80 times per minute in a healthy state, it slows down to up to 40 beats per minute in this disease because the stimulus transmission from the sinus node on the right atrium to the AV node above the right ventricle is insufficient.

The slowing of the heartbeat is also known as bradycardia . Bradyarrhythmia can also occur. Then the normal heartbeat rate is disturbed. AV block can be divided into three different degrees depending on the symptoms.

In the 1st degree there is only a slowing down of the stimulus conduction, which does not cause any symptoms. The 2nd degree denotes the partial failure of the stimulus transmission, while with an AV block of the 3rd degree there is no longer any stimulus conduction.

Causes

An AV block occurs most frequently with increasing age, because the impulse conduction in the heart also ages and thus reduces its performance. Other possible causes include inflammation of the heart muscle and a disruption in the body’s electrolyte balance. Above all, an increased potassium level should be mentioned here.

Taking certain medications, such as digitalis, quinidine , or beta- blockers , can also be a cause. An AV block can also occur temporarily with an underactive thyroid gland , as well as with congenital heart defects or chronic heart diseases such as Lenègre’s disease or coronary heart disease. A heart attack rarely triggers an AV block.

Symptoms, Ailments & Signs

In the worst case, the affected person can die from the AV block. This leads to cardiac arrest . If this is not treated quickly enough, the affected person dies. However, this case usually only occurs if the AV block is not treated and the symptoms are ignored.

One of the main signs and symptoms of AV block is a slow pulse. The pulse itself is often also irregular, which can manifest itself in a strong palpitations. Cardiac arrhythmias also generally occur, which have a negative effect on the quality of life of those affected. The patients often appear tired and exhausted and no longer actively participate in everyday life.

Furthermore, circulatory problems or dizziness occur. This can also lead to unconsciousness , in which the person concerned can injure himself by falling. Most patients also appear pale as a result of the AV block and suffer from severe spasms .

The cramps occur mainly in the chest area and can also lead to fear of death. Many of those affected also develop psychological symptoms as a result of the AV block and suffer from depression and various mental disorders . Symptoms usually worsen if AV block is not treated.

Diagnosis & History

With the recording of the medical history, the doctor already has indications of an AV block. The diagnosis is finally made with an electrocardiogram ( ECG ). The ECG examination is completely painless for the patient. It is used to obtain a graphic representation of the cardiac currents. By comparing the curves with those of a healthy heart, the doctor can determine exactly where the stimulus transmission is disturbed and how severe the disturbance is.

If the AV block only occurs temporarily, a long-term ECG is often also carried out. The patient receives a mobile recording device that is worn for at least 24 hours. To clarify the cause of an AV block, a completely painless ultrasound examination ( echocardiography ) of the heart can also be carried out.

A blood test to determine the electrolytes potassium and sodium is also important . Since first and often second-degree AV block usually does not cause any symptoms, it is advisable to have regular ECG examinations. Third-degree AV block can lead to brief fainting spells. If left untreated, it leads to permanent cardiac insufficiency .

Complications

Complications arising from untreated AV block depend on its etiology and severity. Lighter forms are usually not noticed by those affected and only have a minimal impact. In severe forms, the signals generated by the sinus node, which spread through the atria and lead to their contraction, are not or only incompletely transmitted.

The AV node blocks signals from being transmitted to the ventricles. Typical complications of untreated AV block are short-term dizzy spells and short-term insufficient supply of the retina, so that the affected person “blacks out”, especially after physical exertion. In many cases, there are also short-term fainting spells.

The complications described are based on a lack of oxygen supply , to which the sensitive eyes and the semicircular canals in the inner ear react early with symptoms. If the causative factors are not eliminated, complete AV block can develop, which usually leads to an activation of the second back-up system, the ventricular escape rhythm. The ventricles then contract at the very low and life-threatening rate of 20 to 40 beats per minute.

In special cases, an immediately life-threatening cardiovascular arrest can also occur. If the causes of the AV block can be identified and eliminated, no further complications are to be expected. In many cases, the therapy consists of the implantation of a cardiac pacemaker, which allows a largely uncomplicated lifestyle if certain special features are taken into account.

When should you go to the doctor?

The heart’s atrioventricular (AV) node is made up of specialized heart muscle cells and is part of the heart’s conduction system. It is located in the dividing wall between the right and left atrium near the dividing walls of the two ventricles. Its job is to transmit the electrical contraction signal generated by the sinus node to the ventricular system with a slight delay, so that the ventricles only contract when the atria are already relaxing again.

There is a wide range of AV blocks, which are divided into grades I, II and III. In grade I, there is only a delayed contraction of the ventricles because the transmission of the contraction signal through the AV node is delayed by more than 200 milliseconds. The symptoms are usually not subjectively noticeable and are only discovered if an electrocardiogram (ECG) is made by chance. Symptoms such as an irregular heart rhythm, dizziness and reduced exertion are only noticeable in severity II.

If such symptoms recur or even persist, a doctor who has an EKG machine should be consulted. The doctor will refer to a cardiologist depending on the diagnosis. In the case of an AV block III, the excitation signal is completely interrupted, so that the so-called ventricular replacement rhythm kicks in, which can produce a heart rate of less than 40 Hertz. It is a life-threatening condition that may be accompanied by fainting and requires immediate clinical attention.

Treatment & Therapy

Treatment for AV block depends on the severity of the condition and its cause. If taking certain medications leads to the occurrence of the cardiac arrhythmia, these must be omitted or replaced by other preparations.

If another disease is responsible, it must be treated in order to achieve a normalization of the heart rhythm. In symptom-free first-degree AV block, no further treatment is often necessary. There are two types of AV block of the second degree, which lead to different prognosis for the patient. If it is an AV block of the Wenkebach type, there are often no symptoms. No treatment is then necessary.

With Mobitz-type AV block and third-degree AV block, a pacemaker may be necessary to relieve the patient’s symptoms. Otherwise, circulatory disorders in the brain or what are known as Adam-Stokes seizures, which in turn can lead to respiratory arrest, can otherwise occur, particularly in the case of third-degree AV block . If an AV block is suspected, a doctor should always be consulted immediately.

Outlook & Forecast

The so-called AV block causes symptoms and disorders in the heart. In the worst case, these disorders can lead to cardiac arrest and thus to the death of the patient. As a rule, patients suffer from a very slow pulse and cardiac arrhythmias. It is also not possible for the person concerned to carry out physical or sporting activities. Severe exertion can lead to dizziness or even loss of consciousness. The affected person feels weak and looks pale. Seizures, which can be associated with pain, are common.

In most cases, a diagnosis can be made at an early stage so that treatment can begin quickly. Other problems arise when certain regions of the body are not supplied with enough oxygen. These can be damaged or die off completely. The pulse can also slow down so much that cardiac arrest finally occurs. This can also occur unexpectedly without prior complications. Treatment usually takes place with the help of drugs or implants that support the heart. This can reduce a large part of the complaints. However, life expectancy is reduced due to AV block.

Prevention

Since an AV block often occurs with increasing age, patients are usually unable to take active preventive measures to avoid it. In general, a healthy lifestyle also helps to prevent heart disease. When taking medication, attention should be paid to the corresponding side effects. If symptoms occur, a doctor should be consulted at an early stage to clarify an AV block.

Aftercare

In the case of an AV block, the patient only has very limited options for aftercare. As a rule, with this disease, a pacemaker must be installed in the patient’s body in order to permanently relieve the symptoms. Early diagnosis and treatment have a very positive effect on the further course of the disease and can prevent the affected person from dying prematurely.

In some cases, the sufferer must also take medication to relieve the symptoms. Regular intake and possible interactions with other medications should be taken into account. The treatment of the AV block should be initiated as soon as the first symptoms appear in order to prevent a possible respiratory arrest.

It is not uncommon for those affected to experience psychological upsets or even depression as a result of the AV block. Discussions with friends or with one’s own family can also have a positive effect on the course of the disease. Contact with other people affected by the disease can also be very useful.

In general, the affected person should not do any strenuous or sporting activities in order not to put unnecessary strain on the heart. A healthy lifestyle with a healthy diet also has a positive effect on the course of the disease. The patient should refrain from smoking.

You can do that yourself

Everyday life and self-help measures when AV block occurs depend on the type and severity of the AV block. A typical problem with AV block is the transmission of the electrical contraction signal generated by the sinus node from the atria to the ventricles. Either the signal is delayed too much or it is not transmitted at all.

A first-degree AV block usually progresses without any subjectively noticeable symptoms. Special behavior in everyday life or even self-help measures are therefore unnecessary in these cases. After a second-degree AV block of the Wenckebach type or Mobitz type has been diagnosed, it is initially advisable to check and adjust prescribed drugs such as cardiac glycosides , beta blockers or calcium antagonists in consultation with the doctor treating you.

As self-help measures and behavior in everyday life, light exercise training without extreme physical strain is recommended, a diet that contains as many natural foods as possible and is particularly rich in omega-3 fatty acids . Omega-3 fatty acids are polyunsaturated fatty acids, a few of which are essential for metabolism and are important components of all membranes and serve as the basis for the body’s synthesis of some hormones.

Regular relaxation exercises such as autogenic training , Qi Gong or yoga are helpful and effective . Complete third-degree AV block is an acute cardiac emergency that requires immediate clinical treatment. In most cases, the implantation of a cardiac pacemaker is necessary.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.