With AV block, the electrical excitation of the Sinus node from the AV node or subordinate structures only delayed (AV block 1st degree), only partially (2 degrees) or not (3 degrees) forwarded to the ventricular muscles. This means that the flow of electrical potentials is interrupted at a certain point from the AV node downwards.
At the 1st degree AV block every potential in the sinus node (pulse pacemaker of the Heart) arises, still forwarded Indeed the transition is slowed down. So there is actually no real blockage here, just a delay.
Symptoms: The 1st degree AV block does not cause symptoms. You can recognize him alone in the EKG.
Diagnosis: In the case of AV block of the 1st degree, an extension of the PQ time can be seen in the ECG, the distance between the P wave and the Q spike is over 0.20 seconds.
therapy: No therapy is required.
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At the 2nd degree AV block individual potentials of the sinus node are not passed on. A distinction is made here between two forms that have different prognoses.
At the 3rd degree AV block (total AV block) there is a total line interruption. The potentials of the sinus node are not passed on. They only lead to the contraction of the atrium. The chambers contract in time with subordinate structures such as of the AV node. This cycle is significantly slower than the sinus rhythm. Atrial actions and chamber actions are no longer properly coordinated. in the EKG one sees P-waves that occur with a normal frequency. However, they are not related to the QRS complexes that occur with a slower frequency. It usually takes a certain amount of time until the AV node or subordinate structures "start" and generate a replacement clock, this is called pre-automatic pause.
$config[ads_text2] not foundThe symptoms of 2nd and 3rd degree AV block arise from the depressed Heart rate and the consequent reduced pumping capacity. This beats through the delayed or completely blocked potentials heart slower. The blood is transported less quickly in the organism. The reduced pumping performance manifests itself primarily through symptoms such as dizziness or syncope (fainting spells), too Adams-Stokes attacks called. Adam Stokes seizures are characterized by an acute feeling of dizziness with subsequent, brief loss of consciousness, which is caused by the reduced blood supply to the brain. Most of the time, the symptoms do not occur under exertion, but rather at rest, since under exertion the heart beats faster and conductivity is improved. In this way the actual disturbance can be absorbed.
There are two additional dangers with total AV block:
An AV block is usually caused by pathological changes in the conduction system. The KHK (Coronary heart disease), a Heart attack and medication can lead to AV block. Mostly it occurs in older people.
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$config[ads_text3] not foundThe diagnosis is based on the anamnesis and the typical ECG (Electrocardiogram) Changes made.
For information on the process and interpretation of an ECG, also read: EKG or AV block due to myocardial inflammation in the EKG
With a relatively frequent and harmless AV block grade 1, the distance between the P wave and the QRS complex is more than 200 ms. Treatment is not necessary and often it is Incidental finding in the EKG.
A distinction is made between a Mobitz type and a Wenckebach type in AV block grade 2. In the Wenckebach type, the distance between the P wave and the QRS complex increases from beat to beat. When a certain distance is reached, a QRS complex disappears. With the Mobitz type, the stimulus is only transmitted to the chamber every 2 to 3 beats, which leads to a irregular formation of a QRS complex leads.
A grade 3 AV block represents the most dangerous and always in need of treatment AV block Here the excitation is sent so undirected via the heart muscle that the atria and ventricle beat in an uncoordinated manner. The normal human pulse and possibly also blood pressure cannot be maintained in this way. Treatment should be carried out quickly, since with an untreated Grade 3 AV block, the normal supply of blood to the body cannot be guaranteed. The uncoordinated spread of excitation makes itself felt in the EKG P waves and QRS complexes noticeable, which do not appear at certain distances from one another. So it can happen that you first see a QRS spike and then two P waves instead of one P wave followed by QRS complex after a certain time.
Grade 3 AV block is not only noticed symptomatically by the patient (loss of performance, tiredness, malaise), but is also noticeable through a restless pulse. The danger of AV block grade 3 is syncope, i.e. temporary loss of consciousness.
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Was the AV block caused by medication or a disease (e.g. a Myocarditis), the focus is on treating this disease and stopping medication. The AV block can then recede.
In most cases, no further therapy is required for the 1st and 2nd degree Wenckebach AV block.
With 2nd degree AV block type Mobitz and a total AV block there is one Pacemaker therapy indexed. Usually an atrial involved system (e.g. DDD) is implanted.
Of the AV block is also called atrioventricular arousal disorder.
This disturbance of the conduction of excitation in the heart affects the Atrioventricular node (AV node) or subsequent structures like that HIS bundle, the two Tawara thigh or the Purkinje fibers.
The excitation can only be passed on slowly or sometimes not at all through the AV block. The AV block usually develops when the tissue shows degeneration because the affected person is older.
Also, certain medications as well as cardiovascular diseases are also like Heart attack a possible reason. This disorder can vary in severity.
Some patients do not notice anything, while others have a slower heartbeat (Bradycardia), but it can go up to one Cardiac arrest to lead.
There are 3 different degrees of disorder, which have different degrees of severity:
