Fibrillation

Fibrillation refers to rapid, irregular, unsynchronized contractions of muscle fibers. In the heart, fibrillation results in ineffective atrial or ventricular contractions and can compromise cardiac output. The two most clinically important forms are atrial fibrillation (AF), in which the atria beat chaotically and irregularly, and ventricular fibrillation (VF), in which the ventricles quiver instead of contracting normally. Fibrillation can occur in other muscles under certain conditions, but in clinical use the term most often refers to cardiac rhythm disturbances.

AF symptoms include palpitations, shortness of breath, fatigue, and lightheadedness; VF presents with sudden collapse and unresponsiveness. AF is usually chronic or paroxysmal, whereas VF is a medical emergency requiring immediate intervention.

Diagnosis is by electrocardiography. AF shows an irregularly irregular rhythm with absent distinct P waves; VF shows chaotic, disorganized waveforms with no identifiable QRS complexes.

Treatment for AF focuses on rate or rhythm control, symptom relief, and stroke prevention with anticoagulation when indicated. Rate control uses beta-blockers or calcium channel blockers; rhythm control may involve antiarrhythmic drugs or ablation. Long-term management may include consideration of anticoagulation to reduce stroke risk, guided by risk scoring. For VF, immediate defibrillation, CPR, and management of reversible causes are essential; long-term options include implantable cardioverter-defibrillators in selected patients.

Prognosis depends on the type and underlying heart disease. AF increases the risk of stroke and heart-related complications, while VF is immediately life-threatening but can be reversed with prompt resuscitation.