The article "SVT Quest: The Adventure Diagnosing Narrow QRS Tachycardia" by Koichi Nagashima, Gregory F. Michaud, Reginald T. Ho, and Yasuo Okumura reviews the diagnostic challenges and techniques for distinguishing supraventricular tachycardias (SVTs). The authors outline a three-step process to differentiate narrow QRS tachycardias, focusing on atrial tachycardia (AT), orthodromic reciprocating tachycardia (ORT), and atrioventricular nodal reentrant tachycardia (AVNRT). Each step involves specific diagnostic maneuvers, such as V-A-V or V-A-A-V responses, ΔAA intervals, differential atrial overdrive pacing, and the last entrainment sequence. The article also discusses the challenges and limitations of these techniques, emphasizing the need for multiple maneuvers to make a definitive diagnosis. The authors highlight the continuous cycle of discovery and refinement in electrophysiology, where new insights and techniques are constantly being developed to improve diagnostic accuracy. The article concludes by acknowledging the ongoing nature of the diagnostic journey in electrophysiology.The article "SVT Quest: The Adventure Diagnosing Narrow QRS Tachycardia" by Koichi Nagashima, Gregory F. Michaud, Reginald T. Ho, and Yasuo Okumura reviews the diagnostic challenges and techniques for distinguishing supraventricular tachycardias (SVTs). The authors outline a three-step process to differentiate narrow QRS tachycardias, focusing on atrial tachycardia (AT), orthodromic reciprocating tachycardia (ORT), and atrioventricular nodal reentrant tachycardia (AVNRT). Each step involves specific diagnostic maneuvers, such as V-A-V or V-A-A-V responses, ΔAA intervals, differential atrial overdrive pacing, and the last entrainment sequence. The article also discusses the challenges and limitations of these techniques, emphasizing the need for multiple maneuvers to make a definitive diagnosis. The authors highlight the continuous cycle of discovery and refinement in electrophysiology, where new insights and techniques are constantly being developed to improve diagnostic accuracy. The article concludes by acknowledging the ongoing nature of the diagnostic journey in electrophysiology.