Contributor: Travis Barlock, MD Educational Pearls: SVT: supraventricular tachycardia Pharmacotherapy for SVT includes drugs that block the AV node, such as adenosine EKG criteria before adenosine administration in SVT Regular rhythm Monomorphic: ​​all QRS complexes are identical If the EKG is polymorphic, with QRS complexes displaying changing morphologies, it is unsafe to administer adenosine  Adenosine can worsen polymorphic VTach and lead to VFib References Ganz, Leonard I., and Peter L. Friedman. “Supraventricular Tachycardia.” New England Journal of Medicine, vol. 332, no. 3, 19 Jan. 1995, pp. 162–173, https://doi.org/10.1056/nejm199501193320307. Smith JR, Goldberger JJ, Kadish AH. Adenosine induced polymorphic ventricular tachycardia in adults without structural heart disease. Pacing Clin Electrophysiol. 1997;20(3 Pt 1):743-745. doi:10.1111/j.1540-8159.1997.tb03897.x Viskin, Sami, et al. “Polymorphic Ventricular Tachycardia: Terminology, Mechanism, Diagnosis, and Emergency Therapy.” Circulation, vol. 144, no. 10, 7 Sept. 2021, pp. 823–839, https://doi.org/10.1161/circulationaha.121.055783. Summarized by Meg Joyce, MS1 | Edited by Meg Joyce & Jorge Chalit, OMS3 Donate: https://emergencymedicalminute.org/donate/