atrioventricular block
Introduction
Introduction to atrioventricular block Atrioventricular block refers to impulsive blockage during atrioventricular conduction. Divided into two categories of incompleteness and completeness. The former includes first- and second-degree atrioventricular block, the latter also known as third-degree atrioventricular block, and the block can be in the atria, atrioventricular node, His bundle and double bundle. basic knowledge The proportion of illness: 0.012% Susceptible people: no special people Mode of infection: non-infectious Complications: myocardial infarction arrhythmia
Cause
Atrioventricular block
The following factors often cause this disease:
1 Myocardial inflammation is most common for a variety of reasons, such as rheumatic, viral myocarditis and other infections.
2 vagus nerve excitement, often manifested as transient atrioventricular block.
3 drugs: such as digitalis and other antiarrhythmic drugs, most of the discontinuation of the drug, atrioventricular block disappeared.
4 various organic heart diseases such as coronary heart disease, rheumatic heart disease and cardiomyopathy.
5 high blood potassium, uremia and so on.
6 idiopathic conduction system fibrosis, degeneration and so on.
7 trauma, accidental injury during cardiac surgery or affecting atrioventricular conduction tissue can cause atrioventricular block.
Prevention
Atrioventricular block prevention
Atrioventricular block, caused by conduction disorder between the atrial-chamber, according to the condition of the disease is divided into I, II, III degrees, found that the conduction delay should actively find the cause, such as II degree II or III degree AVB When the drug treatment is ineffective, a permanent artificial cardiac pacemaker can be installed. After the operation, normal life and work can be maintained. If there is no symptom, it can be temporarily used without treatment. Usually pay more attention to physical examination and regular life. It is also necessary to stop drinking alcohol.
Complication
Atrioventricular block complications Complications, myocardial infarction, arrhythmia
The disease often occurs as a complication of other diseases, such as acute inferior myocardial infarction, hyperthyroidism, pre-excitation syndrome, etc. can cause the disease, the complications caused by this disease are rare, but once it occurs, it is very Danger, such as high atrioventricular block can be complicated by ventricular fibrillation, patients with ventricular fibrillation before electrocardiogram often have frequent ventricular premature beats, ventricular tachycardia, and most patients have fatigue, palpitations, chest tightness, panic, irritability Symptoms, so the patient should be prepared for rescue in the clinic. The rescue of ventricular fibrillation should be divided into seconds. The ventricular fibrillation often has aura. The ventricular tachycardia is a prelude. Immediately after the discovery, antiarrhythmic drugs are given to avoid Serious complications have occurred.
Symptom
Atrioventricular block symptoms Common symptoms Bradycardia, dizziness, frequent atrial premature beats, convulsions, atrioventricular block, fatigue, transient fainting, vaginal discharge, cerebral ischemia
Patients with atrioventricular block were often asymptomatic, and the first heart sound of the apex was weakened during auscultation. This was due to the prolongation of the PR interval and the closure of the atrioventricular valve leaf at the beginning of ventricular contraction.
Patients with second-degree type I atrioventricular block may have a heartbeat sensation. Patients with second-degree type II atrioventricular block are often fatigued, dizzy, fainting, convulsions, and cardiac insufficiency, often developing to completeness in a relatively short period of time. Atrioventricular block, whether the heart rhythm is auscultated or not, depends on the change in the proportion of atrioventricular conduction.
The symptoms of complete atrioventricular block depend on whether the ventricular arrhythmia and ventricular rate and the basic condition of the myocardium are established. If the ventricular arrhythmia is not established in time, ventricular arrest occurs, and the autonomous rhythm is higher, such as the His bundle. Below, the ventricular rate is as fast as 40-60 beats / min, the patient may be asymptomatic, the ventricular autonomous rhythm point of the double bundle branch lesion is very low, the ventricular rate is slower than 40 beats / min, and cardiac dysfunction and cerebral ischemia may occur. Syndrome (Adams-Stokes, Syndrome) or sudden death, slow ventricular rate often causes increased systolic blood pressure and pulse pressure widening.
Examine
Atrioventricular block
The examination method of this disease mainly depends on the electrocardiogram:
1, once atrioventricular block:
1P-R interval > 0.20 seconds;
2 After each P wave, there are QRS complexes.
2, second degree atrioventricular block: some atrial agitation can not be transmitted to the ventricle, some P wave no QRS wave group, the atrioventricular conduction ratio may be 2:1; 3:2; 4:3..., second degree Atrioventricular block can be divided into two types, type I is also known as Wen's phenomenon, or Mohs type I, type II is also known as Mohs type II.
(1) Second degree type I block - Wen's phenomenon
The 1P-R interval is gradually extended until the P wave is blocked and the ventricle is leaked;
The 2R-R interval is gradually shortened until the P wave is blocked;
3 The RR interval containing the blocked P wave is shorter than the sum of the two PP intervals.
(2) second degree type II atrioventricular block Mohs type II
The 1P-R interval is fixed and can be normal or extended;
The 2QRS wave group has intermittent leakage, and the degree of blockage can be changed frequently, which can be 1:1; 2:1; 3:1; 3:2; 4:3, etc., the QRS complex of the lower pass is mostly bundle-conducting Blocking pattern.
The first and second degree of type I atrioventricular block, the block site is mostly at the atrioventricular node, and the QRS complex does not widen; the second degree of type II atrioventricular block, the block is more in the Greek Below the beam, the QRS complex is often widened.
(3) Complete atrioventricular block
The 1P wave is independent of the QRS complex;
2 atrial rate is faster than ventricular rate, atrial rhythm may be sinus or originated from ectopic;
3 ventricular rhythm is maintained by the junction zone or ventricular autonomous pacemaker.
The shape of the QRS complex mainly depends on the location of the block. If the block is located above the branch of the His bundle, the escape beat point originates from the high ventricular arrhythm near the branch of the atrioventricular junction, and the QRS complex does not. Widening, if the block is located in the double bundle branch, the escape rhythm is low ventricular arrhythmia, the QRS complex is widened or deformed, and the rate of high escape rhythm in the adjacent atrioventricular junction is often between 40-60 beats per minute. The rate of low ventricular autonomic rhythm is between 30-50 times per minute.
Diagnosis
Diagnostic diagnosis of atrioventricular block
An electrocardiogram can be used to determine the diagnosis and should be differentiated as incomplete (I degree and II degree) or complete (III degree) atrioventricular block. If necessary, the conditional person can also use the His bundle beam diagram.
