AFib

Atrial fibrillation (AF) is a supraventricular tachyarrhythmia in which atrial electrical activation becomes disorganized. The atria no longer contract as a coordinated unit, so the AV node receives irregular impulses and conducts them unpredictably. The result is the classic irregularly irregular ventricular rhythm. Two consequences matter immediately. Loss of effective atrial contraction reduces ventricular filling, particularly when the ventricle is stiff or the patient has heart failure. Irregular, often rapid ventricular activation then shortens diastole further, reducing filling time and sometimes worsening myocardial oxygen demand. In the left atrial appendage, ineffective contraction allows blood stasis and thrombus formation; embolization can produce ischaemic stroke or systemic embolism even when the ventricular rate is not dramatically fast. AF is sustained by electrical and structural remodelling. Atrial stretch, fibrosis, inflammation and autonomic influences make recurrent fibrillation easier to initiate. Common contributors include age, hypertension, heart failure, valvular disease, obesity, sleep-disordered breathing, alcohol, thyroid disease and acute illness. Treating a trigger may terminate an episode, but it does not by itself remove the patient’s long-term embolic risk. Use the Canadian pattern terminology accurately: -...