What is atrial fibrillation?

Atrial fibrillation is what we often call arrhythmia. The harm this symptom brings to the body is immeasurable. From the clinical manifestations, there are many causes of this disease, such as organic heart disease, including rheumatic heart disease, coronary heart disease, hypertensive heart disease, hyperthyroidism, sick sinus syndrome, cardiomyopathy, etc.; it may also be caused by preexcitation syndrome.

1. Organic heart disease

(1) Rheumatic heart disease:

It accounts for about 33.7% of the causes of atrial fibrillation, with mitral stenosis and insufficiency being the most common.

(2) Coronary heart disease:

The incidence of atrial fibrillation in patients with angina pectoris due to coronary heart disease confirmed by coronary angiography is 1.5%, the incidence of atrial fibrillation in patients with old myocardial infarction is 3.8%; and the incidence in patients with acute myocardial infarction is 8.2%. Among patients who underwent coronary angiography due to chest pain and whose coronary arteries were confirmed to be normal, the incidence of atrial fibrillation was 11%. In short, the incidence of coronary heart disease is low.

(3) Hypertensive heart disease:

The lumens of many small arteries in the atrial muscle may be narrowed or completely occluded due to intimal thickening, causing ischemic changes and fibrosis in the local myocardium.

(4) Hyperthyroidism:

In the early stage, the myocardium has focal necrosis and lymphocyte infiltration. In patients with a long course of the disease, the myocardium often shows fine localized fibrosis, with an incidence rate of 5%, which is more common in patients aged 40 to 45 years. It is less common in young patients, and even if it occurs, it is mostly paroxysmal.

(5) Sick Sinus Syndrome:

When the focal muscle fiber structure of the sinoatrial node artery is dysplastic, the collagen structure is abnormal, and the degeneration around the sinoatrial node, especially the degeneration around the sinoatrial node and the abnormality of the sinus impulse, can promote the occurrence of atrial fibrillation.

(6) Cardiomyopathy:

Various types of cardiomyopathy are often accompanied by focal atrial myocardial inflammation, degeneration or fibrosis, and atrial enlargement, which can easily lead to the occurrence of atrial fibrillation. Among them, atrial fibrillation is often the first manifestation of the disease in patients with alcoholic cardiomyopathy, and the incidence rate is high.

(7) Other heart diseases:

Such as cor pulmonale (the incidence rate is 4% to 5%, mostly paroxysmal, and the attacks will decrease as respiratory function improves); chronic constrictive pericarditis; congenital heart disease, etc. Atrial fibrillation is a focal origin atrial fibrillation with increased automaticity; some paroxysmal, some persistent and chronic atrial fibrillation are caused by local micro-reentry mechanisms in the atrium, pulmonary veins and vena cava.

2. Preexcitation syndrome

This may be because the refractory period of the bypass pathway in patients with preexcitation syndrome is very short. Once the reentry conditions are established, the impulse through the bypass pathway increases, and this impulse reenters the left atrium during the stress period, which can induce atrial fibrillation. The incidence of preexcitation complicated by atrial fibrillation is 11.5% to 39%. Preexcitation syndrome complicated by atrial fibrillation is considered a serious condition because the bypass pathway does not have the protective effect of physiological conduction delay like the atrioventricular node, so the ventricular rate transmitted through the bypass pathway is often above 180 beats/min, seriously affecting the heart's blood output.

3. Other diseases

(1) Systemic infiltrative diseases: systemic lupus erythematosus, scleroderma, leukemia, amyloidosis, etc.

(2) Pulmonary and systemic infections and chronic lung failure.

(3) Cardiac surgery and trauma.

(4) Poisoning by digitalis, aconitine, nicotine, etc. can all induce atrial fibrillation.

(5) Various cardiac catheterization procedures, transesophageal electrical stimulation, and electrical cardioversion can directly induce atrial fibrillation.

(6) Excessive drinking and smoking, emotional agitation, excessive smoking, and urination can directly cause atrial fibrillation or induce it on the basis of existing heart disease.

4. Familial Atrial Fibrillation

It is caused by gene mutation and the inheritance mode is AD. It mostly occurs after adulthood and is paroxysmal. Atrial fibrillation occurs and ends unknowingly. The symptoms of atrial fibrillation are mild and are mostly triggered by fatigue, mental stress, infection, pain, drinking, smoking, etc. Heart function remains normal. The prognosis is generally good.

5. Unknown cause

Idiopathic atrial fibrillation in healthy people often has no evidence of organic heart disease.