What Is Third-Degree Heart Block?

Third-degree atrioventricular block is also called complete atrioventricular block, which means that the conduction between the atrioventricles is completely blocked, and all atrial impulses cannot flow into the ventricle, causing the atria and ventricles to move independently. Time is completely out of touch. Blocks can occur in the atrioventricular node (junction), Heath bundle, or bilateral bundle branch system. Complete atrioventricular node block is usually reversible, usually caused by inferior myocardial infarction, acute myocarditis, or digitalis poisoning; while complete AV block is usually permanent, and acute forms Caused by parietal myocardial infarction, the chronic type is often caused by degenerative changes in the conduction system (bilateral bundle branch).

Third-degree conduction block

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Third-degree atrioventricular block is also called complete atrioventricular block, which means that the conduction between the atrioventricles is completely blocked, and all atrial impulses cannot flow into the ventricle, causing the atria and ventricles to move independently. Complete

Third-degree atrioventricular block is also called complete atrioventricular block, which means that the conduction between the atrioventricles is completely blocked, and all atrial impulses cannot flow into the ventricle, causing the atria and ventricles to move independently. Time is completely out of touch. Blocks can occur in the atrioventricular node (junction), Heath bundle, or bilateral bundle branch system. Complete atrioventricular node block is usually reversible, usually caused by inferior myocardial infarction, acute myocarditis, or digitalis poisoning; while complete AV block is usually permanent, and acute forms Caused by parietal myocardial infarction, the chronic type is often caused by degenerative changes in the conduction system (bilateral bundle branch).

(1) P wave and QRS wave have their own laws, which are independent of each other, and the atrial rate is faster than the ventricular rate.

(2) If the block occurs at the atrioventricular junction, the QRS wave is normal with a frequency of 40 to 60 times / minute.

(3) If the block occurs below the branch of the His bundle, and the ventricular pacing point originates from the ventricle, the QRS wave is deformed at a frequency of 20 to 40 beats per minute.

The clinical manifestations of third-degree atrioventricular block depend on the original cardiac function and the rate of ventricular rate. Medical education, Yuwang | Collect and organize patients often have dizziness, fatigue, palpitations, chest tightness, severe cases of cardiogenic syncope, angina pectoris or heart failure. Physical signs: The heart rate is slow and regular, the first heart sound varies in strength, and sometimes it is particularly loud (cannon sound). It is the result of the phase changes of the atrioventricular contraction. Occasionally, the atrial sound can be heard, and sometimes it is easier to hear the low during the interval Blunt atrial sounds, jugular vein pulsations. Due to the increase in ventricular diastolic filling and stroke volume, patients may have increased systolic blood pressure, increased pulse pressure, and even water pulse.

If the ventricular rate is more than 40 beats per minute, and the rhythm point is stable, and there are no obvious symptoms, the cause can be treated; for example, the ventricular rate is too slow, the QRS wave is deformed (block at the complete junction), and the cardiac source has occurred. Patients with sexual syncope should be treated with an artificial pacemaker. Before pacemaker treatment, atropine, 654.2, isoproterenol, etc. can be tried. We used asthma (containing isopropyl adrenaline) to treat one case of acute myocardial infarction with third-degree atrioventricular block, and the heart rate increased from 38 beats / min to 51 beats / min.