1. Paroxysmal supraventricular tachycardia (PSVT)  (Trust Mark: Doctor-Reviewed)
Paroxysmal supraventricular tachycardia (PSVT) is an occasional rapid heart rate. "Paroxysmal" means from time to time.• Reviewer: Larry A. Weinrauch, MD, Assistant Professor of Medicine, Harvard Medical School, and Private practice specializing in Cardiovascular Disease, Watertown, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

2. Arrhythmias  (Trust Mark: Doctor-Reviewed)
An arrhythmia is a disorder of the heart rate (pulse) or heart rhythm, such as beating too fast (tachycardia), too slow (bradycardia), or irregularly.• Reviewer: Alan Berger, MD, Assistant Professor, Divisions of Cardiology and Epidemiology, University of Minnesota, Minneapolis, MN. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.