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 login to view 2 more bullets Types login to view 7 more bullets Associated conditions login to view 4 more bullets Epidemiology Precipitating factors login to view 3 more bullets Etiology Reentrant circuit involved atrial and/or atrioventricular nodal tissue Presentation Symptoms login to view 4 more bullets Physical exam login to view 1 more bullet Studies Electrocardiogram login to view 6 more bullets Holter monitor login to view 1 more bullet Differential Atrial fibrillation login to view 2 more bullets Treatment Conservative login to view 7 more bullets Medical login to view 7 more bullets Procedural login to view 6 more bullets Complications Tachycardia-mediated cardiomyopathy