case_images: PMC5912266_01
case_images: (A) Twelve-lead electrocardiography before treatment showing regular narrow
  QRS tachycardia with a heart rate of 203 bpm. Lead II does not have an
  isoelectric baseline and indicates atrial flutter with 2:1 atrioventricular
  conduction. (B) Electrocardiogram (II, III, aVF-lead) after
  adenosine triphosphate infusion revealing atrial flutter with an F rate of
  about 400 bpm (2:1 atrioventricular conduction).
case_images: 10.1177_1179546818771700-fig1.jpg
case_images: PMC5912266_01_10.1177_1179546818771700-fig1.jpg
case_images: fig1-1179546818771700
case_images: His 12-lead electrocardiography revealed narrow QRS tachycardia (Figure 1A) and indicated atrial flutter (AF) with 2:1 atrioventricular conduction. Electrocardiography after adenosine triphosphate infusion revealed AF with 2:1 atrioventricular conduction (Figure 1B) and that the M-mode diagnosis of 1:1 atrioventricular conduction was incorrect.
case_images: M-mode echocardiography simultaneously displays the movements of the RV and
  LA close to the atrioventricular junction. Arrows indicate right ventricular
  and left atrial contractions. M-mode indicates 1:1 atrioventricular
  conduction. Ao, aorta; LA, left atrium; LV, left ventricle; RV, right
  ventricle.
case_images: 10.1177_1179546818771700-fig2.jpg
case_images: PMC5912266_01_10.1177_1179546818771700-fig2.jpg
case_images: fig2-1179546818771700
case_images: Surprisingly, M-mode, which simultaneously displays right ventricular and left atrial motions (Figure 2), clearly indicated 1:1 atrioventricular conduction.