Atrioventricular block is an impairment of the conduction of impulses directed from the atrium to the ventricles. A rare pulse and syncope (fainting) conditions become manifestations of heart disease. In severe cases, AV block leads to loss of consciousness, brain oxygen deprivation, and can cause sudden cardiac death. The treatment of atrioventricular block requires pacemaker implantation. After this procedure, the heart rate is completely normalized.
Content
- Causes
- Degrees of heart block
- Symptoms
- Diagnostics
- Treatment
- How to get treatment in the world's leading hospitals
Causes
Atrioventricular block can occur due to functional or organic causes. Functional AV block is potentially a reversible, and often asymptomatic disorder. It can be associated with increased vagal tone, electrolyte disorder, drugs, or toxins. Organic AV block has a worse prognosis and often requires invasive treatment. Even in first-degree heart block, the risk of death from all causes increases.
Atrioventricular conduction disorder is associated with a large number of diseases, which lead to myocardial lesions:
- Coronary artery disease and myocardial infarction (after a heart attack, severe AV blocks develop in 3% of patients).
- Autoimmune inflammation.
- Storage diseases.
- Congenital diseases.
The prevalence of AV block is relatively low – it is detected in 0.5-2% of the population. The risk of pathology increases with age.
Normally, first-degree heart block in children is not associated with structural heart damage. It is detected in 8% of children during ECG and in 20% during 24-hour heart rate monitoring. The main cause is the high tone of the vagus nerve.
Second-degree heart block and higher occurs after surgery to repair congenital heart defects caused by drugs or toxic damage to the myocardium, in anomalies of the cardiac conduction system.
Degrees of heart block
First-degree atrioventricular block. It usually does not cause any symptoms. Atrioventricular conduction is preserved, although it is slowed down.
Second-degree atrioventricular block. Bradycardia is associated with the fact that not all impulses generated by the sinus node located in the atria reach the ventricles. There are two options for this block:
- Mobitz type 1 is more favorable prognostically. Heart conduction is slowed down. Ventricular contractions periodically drop out. Mobitz type 1 is characterized by variability of the PQ interval on the cardiogram. It reflects the period of time between the contractions of the atria and ventricles. In each heartbeat, the PQ interval gets longer. Then one ventricular contraction is absent and the cycle begins again.
- Mobitz type 2 has a constant PQ interval. Not all impulses reach the ventricles, but only every second or every third does. The fewer impulses are received, the lower the pulse rate and the more severe the disease progresses. This is a prognostically unfavorable form of pathology, which often develops after anterior myocardial infarction and is a precursor of complete atrioventricular block.
Third-degree atrioventricular block. This type of block is called complete. There are no impulses passing from the atria to the ventricles. Dissociation of the activity of the atria and ventricles is observed. The atria contract in a normal rhythm. The ventricles no longer receive signals from the sinus node, which causes them to contract at a rate of 60-80 per minute. Now they contract at their own rhythm. The pulse rate depends on the level of damage. If the rhythm is set by the AV node, its frequency is about 40 beats per minute, the bundle of His provides 30 beats per minute, and the Purkinje fibers – 20 beats per minute.
Symptoms
Mobitz 1 first- and second-degree AV blocks usually do not manifest any symptoms.
Mobitz 2 is characterized by attacks of dizziness and fainting. The worst prognosis is in the intermittent type of the disease, when the AV block is either complete or incomplete. In this case, there is no constant ventricular rhythm, and the atrial rhythm is interrupted periodically.
The patients with these conditions develop Morgagni-Adams-Stokes Syndrome. When the flow of impulses from the atria stops, the heart actually arrests for 1-2 minutes or the heart rate is only 10-20 beats per minute. There is not enough oxygen supplied to the brain, so the person loses consciousness. Then the pacemaker of the next order is turned on. The heartbeats are restored and the patient regains consciousness.
Complete AV block, which has a permanent form, proceeds more favorably. In this case, the rhythm is slow but steady. The person does not tolerate physical activity, but usually does not lose consciousness at rest.
Diagnostics
The diagnosis is made by ECG. If the abnormality of AV conduction is not recorded on the cardiogram, ECG is made within 24 hours.
To clarify the diagnosis, an electrophysiological test is performed. With its help, doctors determine the degree of the block.
To determine the causes of AV block, laboratory tests and echocardiography are used. Cardiac MRI, coronary angiography, and cardiac catheterization can be conducted, if indicated.
Treatment
The main treatment method is the implantation of a pacemaker (AP). It is indicated in the following cases:
- Type 2 second-degree atrioventricular block (most of the operations are performed in the case of this type of heart block).
- Second-degree type I atrioventricular block – only in the presence of syncope (fainting) conditions caused by large pauses in the rhythm.
- Complete heart block.
The patients with this disease are implanted with a dual chamber pacemaker. One electrode is placed in the atrium, and the other one in the ventricle. The body of the pacemaker is implanted in the subcutaneous fat of the chest.
The treatment procedure is minimally invasive. The operation is performed under local anesthesia. The doctor makes an incision in the thorax a few centimeters long to implant the body of the pacemaker. The electrodes are delivered to the heart through the blood vessels. The recovery period after such an operation is minimal. The electrical stimulator can serve up to 8 years, and then it will be replaced.
How to get treatment in the world's leading hospitals
You can get diagnostics and treatment of atrioventricular blocks abroad. The Booking Health specialists will select a specialized cardiac surgery hospital for you and organize your trip. Booking Health is a medical tourism provider that has been organizing the treatment of patients from 75 countries in the world's leading hospitals for more than 10 years. Compliance of the quality of the company's work with high international standards is confirmed by the prestigious ISO 9001:2015 certificate.
Both doctors and patient case managers working at Booking Health undergo regular training to gain new medical knowledge and provide effective medical and organizational assistance. Booking Health offers the following benefits for you:
- Selection of a specialized hospital with high treatment success rates.
- Direct communication with your attending physician.
- Preliminary preparation of the medical care program, without repeating previous diagnostic examinations.
- Provision of a favorable cost of treatment, without extra charges and additional coefficients for foreigners (saving up to 50%).
- Doctor's appointment on the most suitable dates.
- Independent control of the medical care program at all its stages.
- Assistance in buying and forwarding medicines.
- Communication with the hospital after the completion of treatment.
- Control of invoices and return of unspent funds.
- Organization of additional diagnostic examinations or rehabilitation (if necessary).
- Top-class service: booking hotels, airline tickets, transfer.
- Interpreting services and assistance of a personal medical coordinator.
Please leave your request on the Booking Health website, and a medical advisor or a patient case manager will contact you on the same day.
Authors: Dr. Nadezhda Ivanisova, Dr. Farrukh Ahmed
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