Atrial Fibrillation

Atrial fibrillation is one of the most common tachyarythmias. There is paroxysmal or persistent form. Paroxysmal form has spontaneous beginning and spontaneous end of fibrillation. In the opposite, persistent form can be ended only by using special therapy (pharmacotherapy or electrical cardioversion).

It can be presented at normal healthy persons but it is quite frequent in patients with :


 * Atrial Dilatation
 * Mitral Stenosis
 * ICHS
 * Sick sinus syndrome
 * Myocarditis
 * Pericarditis
 * Thyreotoxicosis
 * COPD
 * Pulmonary Embolism

Pathophysiology
This kind of arrhythmia is based on focal source of impulses and reentry phenomenon. Focal source is usually localized in left atrium, or in one of pulmonary veins. It leads to unorganized atrial activity with very high rate (400-800/min ). Atrial contraction becomes uneffective. Ventricular response is irregular, because not every atrial repolarization is conducted to ventricles. Common ventricular rate in atrial fibrillation is 150-200/min. In result the heart rate of the patient is not based on physical activity. There is tachycardia at rest and bradycardia in enhanced physical activity.

Symptoms

 * palpitations
 * dyspnea
 * tiredness
 * heart failure
 * pulmonary edema
 * or no symptoms…
 * ECG – there is no P wave, in fact P wave is replaced by many F waves with rate 400-800/min, QRS complex is normal but RR distance is irregular (heart rate is irregular).

Complications
Typical complication in AF is thromboembolic disease. Thrombus can be formed in left atrium with risk of peripheral embolization, especially stroke.

Therapy
Therapy of AF is based on:
 * 1) therapy of AF paroxysm,
 * 2) prevention of AF paroxysm (with therapy of cause of AF),
 * 3) ventricle rate modification,
 * 4) prevention of thrombembolic disiese.

Catheter Ablation
Catheter ablation is a method prefered in younger patient resistent on pharmacotherapy with no structural defect in atrial or ventricular myocardium. Then we expect the source of AF in pulmonary veins which will be isolated by catheter ablation.

Prevention of Thrombembolic Disease
The most offten used drug is warfarin, it should be indicated when patient has CHADS2 score 2 and higher. Warfarin can be replaced in special indications (high risk of bleeding) by antiagregants like ASA.

Related articles

 * Electrocardiography