Snapshot A 28-year-old woman presents to the emergency department for palpitations and lightheadedness. She reports that her symptoms began approximately 20 minutes ago and it has not subsided. Medical history is significant for hyperthyroidism. Vital signs are significant for a blood pressure of 135/95 mmHg and a pulse of 155/min. An electrocardiogram is performed that shows a narrow QRS-complex tachyarrhythmia. Carotid sinus massage is performed and her symptoms do not improve. Intravenous adenosine is instituted and her pulse decreases to 79/min. Introduction Definition a tachyarrhythmia that originates above the ventricles (e.g., atrial or atrioventricular node tissues) also known paroxysmal supraventricular tachycardia (SVT) Types atrial fibrillation atrial flutter focal atrial tachycardia multifocal atrial tachycardia atrioventricular reentrant tachycardia atrioventricular nodal reentrant tachycardia Wolff-Parkinson-White syndrome Associated conditions acute myocardial infarctions preexcitation syndromes atrial septal defects chronic lung disease Epidemiology Precipitating factors excessive caffeine or alcohol hyperthyroidism illicit drug use Etiology Reentrant circuit involved atrial and/or atrioventricular nodal tissue Presentation Symptoms palpitations anxiety presyncope/lightheadedness chest pain Physical exam tachycardia Studies Electrocardiogram tachycardia narrow or wide QRS complex if a wide QRS complex is noted, it must be differentiated from a ventricular tachycardia a wide QRS complex can be seen in SVT if there is login to view 2 more bullets Holter monitor consider a 24-hour Holter monitor in patients if the tachycardia is not present Differential Atrial fibrillation differentiating factor narrow QRS complex with an irregularly irregular rhythm Treatment Conservative vagal maneuvers indication login to view 1 more bullet examples login to view 3 more bullets Medical intravenous adenosine indication login to view 1 more bullet AV nodal blocking agents beta-blockers calcium channel blockers login to view 1 more bullet Procedural synchronized cardioversion indication login to view 1 more bullet radiofrequency catheter ablation indication login to view 1 more bullet Complications Tachycardia-mediated cardiomyopathy