Snapshot A 66-year-old man presents to the emergency deparment with palpitations and lightheadedness. The patient has been experiencing these symptoms for the past few days. He reports mild chest discomfort. Medical history is significant for hypertension, type 2 diabetes mellitus, and rheumatic heart disease. An electrocardiogram is immediately performed, which demonstrates a narrow QRS complex tachyarrhythmia that is irregularly irregular. (Atrial fibrillation) Introduction Aberrant rhythms can occur anywhere along the cardiac conduction system (SA node to a single cardiomyocyte) these aberrant rhythm can originate from the atrium (thus a supraventricular arrhythmia) ventricles Etiology there are a number of causes and they include myocardial infarction cardiac scarring can interrupt the cardiac conduction system atrial stretch alters the cardiac conduction system (e.g., significant mitral stenosis) reentrant circuit accessory pathway (e.g., atrioventricular re-entry tachycardia) normal atrioventricular node (e.g., atrioventricular nodal reentrant tachycardia) Symptoms asymptomatic palpitation light headedness syncope sudden cardiac death Atrial Arrhythmias Type Electrocardiogram Findings Treatment Comments Atrial fibrillation A tachyarrhythmia that is irregularly irregular rhythm and has absent P-waves Stable patients rate control e.g.,β-blockers and non-dihydropyridine calcium channel blockers rhythm control e.g.,amiodarone Unstable patients synchronized cardioversion Anticoagulation options include aspirin warfarin new oral anticoagulant (NOAC) e.g., dabigatran Most common type of atrial arrhythmia A dilated left atrium can result in atrial fibrillation e.g., mitral stenosis Can result in a thromboembolic event (e.g., stroke) The ventricular rate is determined by the AV node refractory period Often originates in the pulmonary veins Atrial flutter A tachyarrhythmia with a"sawtooth"appearance Stable patients treat similarly as atrial fibrillation Unstable patients synchronized cardioversion Definitive treatment is with catheter ablation Caused by are-entrant circuit in the right atrium Sick sinus syndrome A bradyarrhythmia with episodes of tachycardia acute patients assess for reversible causes such as medications (calcium channel blockers, digoxin, lithium) chronic patients anticoagulation pacemaker placement --