Etiology
Common causes of atrial fibrillation include hypertension, coronary artery disease, cardiac surgery, valvular disease, heart failure, cardiomyopathy, congenital heart disease, pulmonary embolism, hyperthyroidism, etc. It is associated with alcohol consumption, mental stress, water-electrolyte or metabolic imbalance, and severe infections; in addition, it can be combined with other types of arrhythmias.
Classification
There is no uniform definition for the classification of atrial fibrillation, which can be divided into paroxysmal atrial fibrillation, persistent atrial fibrillation and permanent atrial fibrillation according to the duration. Paroxysmal atrial fibrillation is usually considered to be a condition that can return to sinus rhythm within 7 days on its own, usually for less than 48 hours; persistent atrial fibrillation is a condition that lasts for more than 7 days and requires drugs or electric shock to return to sinus rhythm; permanent atrial fibrillation is a condition that cannot return to sinus rhythm or recurs within 24 hours after the return.
Atrial fibrillation is classified according to the presence or absence of underlying heart disease as pathological atrial fibrillation (atrial fibrillation with other underlying heart disease) and idiopathic atrial fibrillation (no underlying heart disease on clinical examination). Idiopathic atrial fibrillation tends to occur in younger people, mostly younger than 50 years of age, and is sometimes referred to as isolated atrial fibrillation.
Clinical manifestations
1. Palpitations
Feeling of disturbed or rapid heartbeat, physical fatigue or exertion.
2, vertigo
Dizziness or fainting.
3, chest discomfort
Pain, pressure or discomfort.
4.Shortness of breath
Breathing difficulty during mild physical activity or at rest; in addition, some patients may not have any symptoms.
In atrial fibrillation, the atria lose their contractile function, and blood is easily stagnated in the atria and forms thrombi, which can be dislodged and travel throughout the body, leading to cerebral embolism (stroke) and arterial embolism of the limbs (even amputation in severe cases). Risk factors for stroke in patients with atrial fibrillation include a history of previous embolism, hypertension, diabetes, coronary artery disease, heart failure, and left atrial enlargement.
Examination
Initial diagnosis of atrial fibrillation can be made based on clinical symptoms and signs, but ECG examination is required to confirm the diagnosis; for patients with transient episodes of atrial fibrillation that are difficult to capture, tests such as ambulatory ECG are required.
Treatment
1.Treatment principles
(1) Restore sinus rhythm Only by restoring sinus rhythm (normal heart rhythm) can we achieve the goal of completely treating atrial fibrillation, so any patient with atrial fibrillation should try the treatment method of restoring sinus rhythm.
(2) Control of rapid ventricular rate For patients with atrial fibrillation who cannot regain sinus rhythm, medications can be used to slow down the faster ventricular rate.
(3) Prevention of thrombosis and stroke If sinus rhythm cannot be restored in atrial fibrillation, anticoagulants can be used to prevent thrombosis and stroke.
For certain diseases such as hyperthyroidism, acute alcoholism, and drug-induced atrial fibrillation, atrial fibrillation may disappear on its own after removing the cause, or it may persist.
2.Medication
Medication is still an important treatment for atrial fibrillation, which can restore and maintain sinus rhythm, control ventricular rate and prevent thromboembolic complications.
Drugs to restore sinus rhythm (normal rhythm): For new-onset atrial fibrillation, because of its high rate of self-recurrence within 48 hours (about 60% within 24 hours), it can be observed first, and propafenone or flucarbamate can also be used as a method of administration. For those with atrial fibrillation lasting more than 48 hours but less than 7 days, intravenous medications such as flecainide, dofetilide, propafenone, ibuprofen and amiodarone can be used to transcend the rhythm with a success rate of up to 50%. For AF episodes lasting longer than a week (persistent AF), the effectiveness of pharmacological cardioversion is greatly reduced. The commonly used and proven effective drugs include amiodarone, Ibutilide, and dofetilide.
Drugs to control the ventricular rate (frequency control): Controlling the ventricular rate can ensure the basic function of the heart and minimize the cardiac dysfunction caused by atrial fibrillation. Commonly used drugs include.
(1) beta-blockers The most effective, most commonly used and often applied alone.
(2) Calcium channel antagonists such as verapamil and diltiazem can also be used effectively for ventricular rate control in atrial fibrillation, especially for the control of ventricular rate during exercise than digoxin, and the effect of combining with digoxin is also better than using them alone. It is particularly useful in patients without organic heart disease or with normal left ventricular systolic function and in patients with chronic obstructive pulmonary disease.
(3) Digitalis is the first-line drug for ventricular rate control in atrial fibrillation in emergency situations, and is currently used in clinical practice for ventricular rate control in the presence of left heart failure.
(4) Amiodarone can reduce the ventricular rate in atrial fibrillation, and is not recommended for long-term ventricular rate control in chronic atrial fibrillation, except that amiodarone may be preferred in combination with digitalis when other drugs are ineffective or contraindicated, or when atrial fibrillation combined with heart failure requires urgent ventricular rate control.
3.Non-pharmacological treatment
Non-pharmacological treatment of atrial fibrillation includes electrical cardioversion (conversion of sinus rhythm), radiofrequency ablation therapy and surgical maze (complete cure of atrial fibrillation).
(1) Electrical cardioversion is a method of restoring sinus rhythm by using two electrode pads placed on the appropriate part of the patient’s chest and distributing electric current through a defibrillator. Electrical resuscitation is indicated for: emergency atrial fibrillation (such as myocardial infarction, extremely fast heart rate, hypotension, angina pectoris, heart failure, etc.), atrial fibrillation with severe symptoms that are difficult for the patient to tolerate, atrial fibrillation that was successfully resuscitated last time and has recurred without maintenance with medication. Electrical resuscitation is not a cure for atrial fibrillation, and the patient’s atrial fibrillation often recurs, and some patients need to continue to take antiarrhythmic drugs to maintain sinus rhythm.
(2) Catheter ablation therapy is suitable for most patients with atrial fibrillation and is less invasive and easily accepted by patients.
(3) Surgical maze surgery Currently, it is mainly used for patients with atrial fibrillation who need cardiac surgery for other heart diseases.
(4) Anticoagulation therapy is necessary to prevent thrombosis and embolism in patients with atrial fibrillation. Anticoagulation therapy with warfarin can reduce the risk of stroke by 68%; however, anticoagulation therapy cannot eliminate atrial fibrillation and cannot improve the clinical symptoms of patients such as palpitations, weakness and heart failure. Patients with atrial fibrillation should be treated with anticoagulation if they have: age ≥ 65 years; a history of previous stroke or transient ischemic attack; congestive heart failure; hypertension; diabetes mellitus
coronary artery disease; left atrial enlargement; and left atrial thrombus detected by echocardiography. Anticoagulation must be supervised by a specialist. Excessive anticoagulation may lead to bleeding, while insufficient anticoagulation strength has no preventive effect, and long-term use of warfarin requires testing.
Long-term use of warfarin requires testing of the national standard ratio (INR), especially at the beginning of the drug, and requires repeated blood tests, which many patients cannot adhere to over the long term. The effects of warfarin are easily influenced by other drugs or diet, and dose adjustment is not easy to control. Some patients who cannot tolerate warfarin can be treated with aspirin or/and clopidogrel. Some new anticoagulants that do not require INR monitoring, such as dabigatran and rivaroxaban, are being used in clinical practice.
Prognosis
Stroke is one of the greatest risks of AF. The incidence of stroke in patients with non-valvular AF is 5.6 times higher than normal, and the incidence of stroke in valvular AF is 17.6 times higher than normal; moreover, the consequences of stroke caused by AF are more serious, with a disability rate of about 25% and a mortality rate of up to 25%.
Prevention
Some patients may need to avoid caffeine-containing substances such as tea, coffee, cola, and some over-the-counter medications. Caution should be exercised with certain cough or cold medications that may contain stimulants that may promote irregular heart rhythms.