Atrial tachycardia with atrioventricular block
Introduction
Introduction to atrial tachycardia with atrioventricular block Atrial tachycardia with atrioventricular block is significantly different from other paroxysmal supraventricular tachycardia in terms of etiology, basic cardiac status, clinical manifestations, ECG changes, treatment and prognosis. basic knowledge The proportion of the disease: the incidence rate of the elderly over 50 years old is about 0.04%-0.09% Susceptible people: no special people Mode of infection: non-infectious Complications: Myocarditis Hyperkalemia
Cause
Atrial tachycardia with atrioventricular block
(1) Causes of the disease
The most common cause is due to the use of digitalis in patients with structural heart disease and heart failure, especially in digitalis patients. A group of 88 patients with structural heart disease have 64 cases of digitalis. 83 cases of paroxysmal atrial tachycardia with atrioventricular block, caused by digitalis, accompanied by significant hypokalemia, when the potassium supplementation treatment has a significant effect, another feature is Digitalis preparations can develop atrial tachycardia with atrioventricular block during the application of small doses. Digitalis poisoning accounts for more than 50% of atrial tachycardia with atrioventricular block.
In patients who are not due to the use of digitalis, atrial tachycardia with atrioventricular block, the main cause is hypokalemia and some organic heart disease, such as coronary heart disease, myocardial infarction, hypertension, lung Heart disease, rheumatic heart disease, etc., also reported that quinidine, isoproterenol, etc., and young people without structural heart disease have this type of atrial tachycardia, there are also reports of atrial tachycardia with room Ventricular conduction block can be converted by atrial flutter in the process of taking quinidine, due to a slow rate of atrial rate, there are reports of paroxysmal atrial tachycardia can be treated with digitalis, before conversion to sinus rhythm Causes varying degrees of atrioventricular block to form atrial tachycardia with atrioventricular block.
(two) pathogenesis
Due to the increased self-discipline of the ectopic excitatory in the room, or due to the triggering of the activation, due to the occurrence of atrioventricular block, the atrial tachycardia caused by reentry can be excluded. This conduction block can be atrioventricular conduction. Obstruction is caused by the presence of atrioventricular block after treatment to restore sinus rhythm. Partial conduction block is caused by atrial tachycardia during conduction in the atrioventricular conduction, conduction delay or conduction due to interference Interruption, concurrent with atrioventricular conduction, this may be due to atrial tachycardia, P'-P' interval is short, P' wave is prone to systolic or early diastolic, prone to interfering atrioventricular block.
Prevention
Atrial tachycardia with atrioventricular block prevention
1. In the correction of organic heart disease, digitalis drugs are often used. During the course of medication, the clinical manifestations of the patients should be closely observed and the blood drug concentration of the drugs should be monitored at any time. Once the digitalis is excessive, the above method can be used.
2. Diet has a section, daily life is always, emotional comfort, work and rest, avoiding evil spirits, appropriate participation in physical exercise to enhance physical fitness.
Complication
Atrial tachycardia with complications of atrioventricular block Complications Myocarditis Hyperkalemia
The sinus block is called sinus block between the sinus node and the atrium. It is called atrioventricular block between the atrium and the ventricle, as well as intraventricular block, indoor block, and bundle branch block. Myocardial inflammation is most common, such as rheumatic, viral myocarditis and other infections. Transient atrioventricular block, rheumatic heart disease and cardiomyopathy, hyperkalemia, uremia, etc.
Symptom
Atrial tachycardia with atrioventricular block symptoms Common symptoms Heart rate irregular tachycardia atrioventricular blockade frequent atrial premature beats atrioventricular tube malformation
The clinical manifestations of atrial tachycardia with atrioventricular block caused by digitalis have the following three forms:
1. Heart failure treated with digitalis had once improved, and then significantly increased again.
2. During the process of using digitalis, the heart rate slowed down and then suddenly accelerated and turned into irregular rhythm.
3. There will be other digitalis poisoning performance, such as nausea, vomiting, and yellow vision.
In patients with heart failure, the heart rate is gradually slowed down during the treatment of digitalis, which often indicates that the condition is improved. If the heart rate is slow and the rule suddenly turns fast and not complete, or the heart failure is significantly increased again, it should be highly alert to atrial heartbeat. In the case of overspeed with atrioventricular block, blood potassium should be measured in time.
Examine
Atrial tachycardia with atrioventricular block
Mainly based on ECG examination:
1.P' wave is an atrial ectopic P' wave. In the case of short burst, it can be seen that it is different from sinus P wave. P' wave can also be retrograde P wave, atrial tachycardia caused by digitalis poisoning. With atrioventricular block, the ectopic P' wave depolarization direction is still normal, but the amplitude is very small, and the P wave with sinus tachycardia is clear, clearly distinct.
2. The P' wave is located before the QRS wave, and the P'-R interval
3. The atrial rate is 150-250 times/min, and the P'-P' interval in the atrial law can be regular or irregular (even 0.12 s difference). About half of the patients caused by digitalis overdose have irregular atrial rate, and With the continued use of digitalis, the room rate has gradually increased.
4. QRS wave is supraventricular, form, and time limit are normal.
5. In the atrioventricular block can have the following forms
(1) Second degree type I atrioventricular block (Figure 1, 2, 3).
(2) Second degree type II atrioventricular block: can be 2:1 ~ 4:1 atrioventricular block, with 2:1 atrioventricular block is the most common (Figure 4, 5).
(3) Alternating Venturi phenomenon (double-layer conduction block) (Fig. 6, 7).
(4) The ventricular rate irregularity is caused by the irregularity of the atrial itself. When the ventricular rate is irregular, it can be misdiagnosed as atrial fibrillation. At this time, attention should be paid to the P' wave law of the V1 lead or esophageal lead.
6. Pressing the carotid sinus, the atrial tachycardia caused by digitalis is not effective with atrioventricular block, but it can cause the degree of atrioventricular block to increase, and the ventricular rate is slowed down, which is caused by non-digitalis The atrial tachycardia with atrioventricular block, after pressing the carotid sinus, the P wave frequency has a significant slowdown, sometimes can terminate the episode, because digitalis can improve the sensitivity of the carotid sinus, so the use of the ocean Rehmannia patients should be careful to press the carotid sinus, atropine can increase the atrial rate of non-digitalis, and no effect on the atrial tachycardia caused by digitalis with atrioventricular block.
7. For atrial tachycardia with atrioventricular block caused by digitalis, the ST-T changes caused by the digitalis effect can be seen on the electrocardiogram, and about 40% of cases can be accompanied by a room. Pre-sexual contraction occurs.
Diagnosis
Diagnosis and differential diagnosis of atrial tachycardia with atrioventricular block
According to the characteristics of the patient's medical history, clinical manifestations and ECG characteristics, a correct diagnosis can be made. This arrhythmia is very difficult to distinguish from other various atrial tachycardia and sinus speed. Because of the atrioventricular block, the P wave that has not been transmitted may be covered by QRS or T wave. Carotid sinus compression or intravenous adenosine may be used. Increase the degree of atrioventricular block to make the P wave better. The esophageal lead electrocardiogram can also be used to confirm the presence of atrioventricular block and atrioventricular block.
A small part of digitalis caused by atrioventricular block with atrial rate of more than 250bpm, the identification of atrial flutter is very important and difficult, the main performance of the room velocity is the presence of equipotential lines between the P waves, and Atrial flutter is characterized by a continuous wave-like baseline (also known as a sawtooth pattern of atrial flutter). In addition, discontinuation of digoxin or potassium supplementation can slow down the frequency of the house and cause digitalis. The speed of the room is terminated. On the contrary, continuing to take digitalis can increase the heart rate of paroxysmal atrial rate caused by digitalis.
