Atrial fibrillation

Introduction Atrial fibrillation ( AF) is the most common persistent arrhythmia. With the increasing incidence of atrial fibrillation, the number of people over the age of 75 can reach 10%. The frequency of atrial excitement during atrial fibrillation is 300-600 beats/min. The heartbeat frequency is often fast and irregular. Sometimes it can reach 100-160 beats/min. It is not only much faster than normal people's heartbeat, but also is not neat, the atrium is lost. Effective shrinkage function. The increase in the prevalence of atrial fibrillation is also closely related to the growth of coronary heart disease, hypertension and heart failure, and atrial fibrillation will become one of the most prevalent cardiovascular diseases in the next 50 years.

Cause

Atrial fibrillation (Af), abbreviated as atrial fibrillation, is one of the most common arrhythmias, and is caused by a number of small reentry rings caused by atrial-dominant reentry rings.

Organic heart disease

(1) Rheumatic heart disease: about 33.7% of the cause of atrial fibrillation, more common with mitral stenosis and insufficiency.

(2) Coronary heart disease: Coronary angiography confirmed coronary heart disease with angina pectoris, the incidence of atrial fibrillation was 1.5%, the incidence of atrial fibrillation in old myocardial infarction was 3.8%, and the incidence of acute myocardial infarction was 8.2%. The incidence of atrial fibrillation was 11% in patients with normal coronary arteries confirmed by coronary angiography. In short, the incidence of coronary heart disease is low.

(3) Hypertensive heart disease: Many small arterial lumens of the atrial muscle may be narrowed or completely occluded due to thickening of the intima, causing ischemic changes and fibrosis of the local myocardium.

(4) Hyperthyroidism: focal myocardial necrosis and lymphocytic infiltration in the early myocardium, the myocardium often showed fine localized fibrosis, the incidence rate was 5%, more common in patients aged 40 to 45 years. Young patients are less common, and even if they occur, they are mostly paroxysmal.

(5) Sick sinus syndrome: When the sinus node arteries have focal dysplasia of the muscle fibers, abnormal collagen structure and degeneration around the sinus node, especially the sinus node degeneration and sinus impulse abnormalities, can promote The occurrence of atrial fibrillation.

(6) Cardiomyopathy: all types of cardiomyopathy, often accompanied by focal atrial muscle inflammation, degeneration or fibrosis, atrial enlargement easily lead to atrial fibrillation, in patients with alcoholic cardiomyopathy, atrial fibrillation is often the disease The initial performance, the incidence is high.

(7) Other heart diseases: such as pulmonary heart disease (incidence rate is 4% to 5%, mostly paroxysmal, and the respiratory function is reduced after the improvement of respiratory function), chronic constrictive pericarditis, congenital heart disease, etc. . Atrial fibrillation is a spontaneously atrial fibrillation with increased autonomy, and some paroxysmal and partial persistent and chronic atrial fibrillation are caused by local micro-reentry mechanisms in the atrium, pulmonary veins, and vena cava.

Pre-excitation syndrome

It may be due to the short-term refractory period of patients with pre-excitation syndrome. Once the reentry conditions are established, the impulses through the bypass increase, and this impulse can be induced to atrial fibrillation after reentry into the left atrial stress period. The incidence of pre-excitation complicated atrial fibrillation was 11.5% to 39%. Pre-excitation syndrome complicated with atrial fibrillation is considered to be serious because the bypass does not have the protective effect of physiological conduction delay like the atrioventricular node, so the ventricular rate transmitted by the bypass is more than 180 times/min, which seriously affects the heart. The amount of blood discharged.

3. Other diseases

(1) Systemic invasive diseases: systemic lupus erythematosus, scleroderma, leukemia, amyloidosis, and the like.

(2) Lung and systemic infections as well as chronic pulmonary insufficiency.

(3) Heart surgery and trauma.

(4) Aflatoxin poisoning, aconitine, nicotine and other poisoning can induce atrial fibrillation.

(5) A variety of cardiac catheterization and transesophageal electrical stimulation, electrical cardioversion, etc. can directly induce atrial fibrillation.

(6) Alcoholism and smoking, emotional excitement, excessive smoking, urination, etc. can occur directly or induce atrial fibrillation based on the original heart disease.

4. Familial atrial fibrillation

The gene is caused by mutation, and the genetic mode belongs to AD inheritance. It occurs mostly after adulthood and is paroxysmal. Atrial fibrillation occurs and terminates unconsciously. The symptoms of atrial fibrillation are mild, mostly induced by fatigue, nervousness, infection, pain, drinking, smoking, etc., and the heart function remains normal. The general prognosis is good.

5. The reason is unknown

Idiopathic atrial fibrillation in healthy people often has no basis for organic heart disease.

Heart disease can also occur. Causes serious complications, such as heart failure and arterial embolism, which pose a serious threat to human health.

an examination

Related inspection

Dynamic electrocardiogram (Holter monitoring) ECG

Atrial fibrillation can be initially diagnosed based on clinical signs and symptoms, but an electrocardiogram is required for diagnosis. For patients with a brief episode of atrial fibrillation, a dynamic electrocardiogram or the like is required.

Differential diagnosis

Differential diagnosis

Atrial fibrillation: P wave disappears, replaced by "f" wave, "f" wave is easier to identify in V1 and II leads, "f" wave frequency is 350-600bpm, RR interval is absolutely equal, if combined completeness The RR interval can be equal when the atrioventricular block is present.

I. Differential diagnosis of atrial fibrillation with differential conduction and ventricular premature contraction

The characteristics of ventricular premature contraction are:

The 1V1 lead QRS wave is unidirectional or bidirectional, and V6 is QS or rS.

2 is more common with left bundle branch block.

3 There is a fixed inter-law interval, followed by a complete compensatory interval.

The starting vector of the 4 malformed QRS wave is different from the normal descendant.

Second, the differential diagnosis of atrial fibrillation with indoor differential conduction and ventricular tachycardia

1 The former's rhythm is mostly irregular: the basic rule is only when the heart rate is extremely fast, while the latter basic rule (the RR interval is only 0.02 to 0.04 s) or absolute rule.

2 The former QRS time limit is mostly 0.12~0.14s, and the variability is large, while the latter QRS time limit can be greater than 0.14s. For example, >0.16s is definitely ventricular tachycardia, and the variability is small.

3 The former has no compensatory interval, and the latter has a joint interval and is fixed. There is a compensatory interval after the termination of the attack.

4 The former has no ventricular fusion wave and the latter has.

The 5S1~V6 lead QRS wave has the same direction, both upwards or downwards, and the height indicates ventricular tachycardia.

6 If there is a continuous malformed QRS wave, such as the directional change of the electric axis. Mostly ventricular tachycardia (torsional ventricular tachycardia).

Third, the pre-excitation syndrome combined with atrial fibrillation and ventricular tachycardia identification of ventricular tachycardia is:

1 ventricular rate is 140 ~ 200 times / min, more than 180 times / min is rare.

2 The ventricular rhythm may be slightly irregular or completely neat, and the RR interval is only 0.02 to 0.04 s.

The 3QRS wave is rarely a right bundle branch block pattern with no pre-shock.

4 can be seen in the ventricle captured, there is a ventricular fusion wave.

The electrocardiogram before and after the onset of 5-ventricular tachycardia can present ventricular premature contractions of the same morphology.

4. The characteristics of pre-excitation syndrome with atrial fibrillation are:

1 ventricular rate is more than 180 ~ 240 times / min.

2 The ventricular rhythm is absolutely irregular, and the difference between RR intervals can be greater than 0.03~0.10s.

The 3QRS wave is malformed, but a pre-shock is visible at the beginning.

4 no ventricle was captured without a ventricular fusion wave.

Before and after the onset of the attack, the ECG showed a pattern of pre-excitation syndrome.

V. Identification of atrial fibrillation and atrioventricular junctional heart rhythm In some cases, the f-wave of atrial fibrillation is very small, so that it cannot be clearly displayed on the conventional electrocardiogram. At this time, it is easy to be misdiagnosed as atrioventricular junction tachycardia. . However, the ventricular rhythm of the atrial fibrillation is absolutely irregular (except for the atrioventricular block). The heart rhythm of the atrioventricular junction is absolutely uniform. In addition, if the gain f wave can be increased, it may appear. If you can trace the f wave in a special lead (such as the esophageal lead). It can be diagnosed as atrial fibrillation.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.