In this Heart Rhythm Challenging Case Discussion, Mayo Clinic cardiology experts Samuel J. Asirvatham, M.D., Abhishek J. Deshmukh, M.B.B.S., Christopher V. DeSimone, M.D., Ph.D., and Siva K. Mulpuru, M.D., M.P.H., and Ammar M. Killu, M.B.B.S., discuss AV nodal reentrant tachycardia (AVNRT).