Incomplete atrial block

Introduction Intra-atrial block, referred to as intra-atrial block, refers to the extension or interruption of the conduction time from the sinus node in the atrium, which is divided into incomplete and complete conduction block. Incomplete atrial block is due to the ectopic activation of the impulse in the atria, which invades the sinus node during the depolarization process, so that the activation cannot be transmitted or delayed.

Cause

(1) The etiology of incomplete atrial block: atrial fibrosis, adipose, amyloidosis and other degenerative changes, hypertrophy and/or dilatation of the left atrium and/or right atrium, atrium Acute or chronic inflammation of the muscle, acute or chronic ischemia of the atrial muscle, or atrial infarction can lead to atrial block. Incomplete atrial block is mostly seen in structural heart disease, such as rheumatic heart disease mitral stenosis, hypertension, heart failure, coronary heart disease, myocardial infarction, myocarditis, some congenital heart disease (such as housing) Interstitial defects, etc., cardiomyopathy, chronic pericarditis, hyperkalemia, increased vagal tone, digitalis and quinidine may lead to incomplete atrial block. Incomplete atrial blockade is not just a block of conduction between the bundle of cells or the internode. In fact, it is often a sign of left atrial hypertrophy, left atrial volume, and persistent or temporary pressure increase in the left atrium, or increased left ventricular end-diastolic pressure.

(2) The etiology of intermittent incomplete atrial block: Intermittent intraventricular block can be seen in all age groups, 7 to 97 years old. There are many cases of organic heart disease reported in China, such as coronary heart disease, cardiomyopathy, hypertensive heart disease, rheumatic heart disease, chronic obstructive pulmonary disease, constrictive pericarditis, and sick sinus syndrome. Intraventricular conduction disorders in the elderly may be associated with degeneration of cardiac conduction tissue. About 36% of those with intermittent intraventricular blockage reported abroad have structural heart disease. Some cases changed from intermittent to fixed (persistent) intraventricular conduction block after several months and years of observation. The occurrence of intermittent intraventricular blockade suggests atrial lesions.

an examination

Related inspection

Electrocardiogram

Incomplete atrial block has no hemodynamic significance, but half of the patients often have recurrent paroxysmal atrial fibrillation or atrial flutter (atrial flutter referred to as atrial flutter, is a common Rapid atrial arrhythmia. Electrocardiogram is a regular flutter wave, atrial activation frequency is 250 ~ 350 beats / min. Atrial flutter can be characterized by paroxysmal and persistent seizures, some patients with atrial flutter can alternate with atrial fibrillation, For the impure atrial flutter, the incidence of atrial flutter increases with age, and the incidence rate of males is about 2.5 times that of females. With the development of mapping technology, the mechanism of atrial flutter has been basically clear, and radiofrequency ablation has gradually become the main treatment. In the medical history, 40% of patients may have a history of atrial premature contraction and atrial tachycardia. Patients may have chest tightness, shortness of breath, and heartbeat.

Differential diagnosis

Intraventricular conduction block: Intraventricular conduction block refers to impulse in the atrial interstitial bundle or room beam block.

Complete atrial block: atrial separation. More common in the critical period of organic heart disease. It also often occurs several hours before the death of critically ill patients. In addition, digitalis poisoning. The effects of uremia and drugs (such as taking amiodarone) can also be seen. More manifested as the clinical manifestations of the primary disease.

Diffuse complete atrial block and sinus-ventricular conduction: both due to hyperkalemia. Only the latter is a wide range of electrical paralysis of the atrial muscles. The atrial muscle loses excitability and conductivity. And the sinus node. The internode and atrioventricular conduction systems are still excitatory and conductive. Sinus agitation can be transmitted to the ventricle; while the conduction and atrial muscles in the atrium of the former are completely excitatory and conductive. It is characterized by sinus arrest. When the sinus arrest is long. Can cause dizziness or syncope. Even A-Syndrome occurs. Long-term sinus arrest is not accompanied by an escape. Can cause sudden death.

Sinus conduction block: the impulse generated by the sinus node, part or all of which can not reach the atria, causing the atrium and ventricle to stop twice or more consecutive times, called sino-auricular block, is less See one of the arrhythmia. Acute sinus block is caused by acute myocardial infarction, acute myocarditis, digitalis or quinidine, and excessive vagal tone. Chronic sinus block is common in coronary heart disease, primary cardiomyopathy, vagal tone or unexplained sick sinus syndrome.

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