An Unusual Type of Long RP Tachycardia - What is the Mechanism?

Case Presentation: An 81 year-old man underwent diagnostic electrophysiologic study because of daily rapid palpitations. His 12-lead ECG and echocardiogram were normal. At baseline, he was in a nearly incessant tachycardia which otherwise was easily inducible with atrial and ventricular stimulation (Figure 1, top). The response of tachycardia to ventricular premature depolarizations (VPDs) and entrainment from the ventricle are shown in Figure 1 (middle, bottom) and Figure 2, respectively. Based upon the tracings, what is the mechanism of tachycardia?

Source: Heart Rhythm - July 11, 2019 Category: Cardiology Authors: Reginald T. Ho Source Type: research