Demonstration of the Anatomical Tachycardia Circuit in Sinoatrial Node Reentrant Tachycardia: Analysis Using the Entrainment Method

<jats:sec xml:lang="en"> <jats:title>Background</jats:title> <jats:p xml:lang="en"> The anatomical tachycardia circuit of sinoatrial node reentrant tachycardia ( <jats:styled-content style="fixed-case">SANRT</jats:styled-content> ) has not been well clarified. This study aimed to elucidate the tachycardia circuit of <jats:styled-content style="fixed-case">SANRT</jats:styled-content> . </jats:p> </jats:sec> <jats:sec xml:lang="en"> <jats:title>Methods and Results</jats:title> <jats:p xml:lang="en"> Exit and entrance of the intranodal sinoatrial node conduction (I‐ <jats:styled-content style="fixed-case">SANC</jats:styled-content> ) of the reentry circuit were identified in 15 <jats:styled-content style="fixed-case">SANRT</jats:styled-content> patients. After identifying the earliest atrial activation site ( <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ) during the tachycardia ( <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ‐ <jats:styled-content style="fixed-case">SANRT</jats:styled-content> ), rapid atrial pacing was delivered from multiple atrial sites to identify the entrainment pacing site where manifest entrainment and orthodromic capture of the <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ‐ <jats:styled-content style="fixed-case">SANRT</jats:styled-content> were demonstrated. Radiofrequency energy was then delivered starting at a site 2 cm proximal to the <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ‐ <jats:styled-content style="fixed-case">SANRT</jats:styled-content> in the direction of the entrainment pacing site and gradually advanced toward the <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ‐ <jats:styled-content style="fixed-case">SANRT</jats:styled-content> until tachycardia termination to localize the I‐ <jats:styled-content style="fixed-case">SANC</jats:styled-content> entrance. The <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ‐ <jats:styled-content style="fixed-case">SANRT</jats:styled-content> was orthodromically captured by pacing delivered from the distal coronary sinus (n=7), high posteroseptal right atrium (n=2), low posteroseptal right atrium (n=2), low anterolateral right atrium (n=2), or coronary sinus ostium (n=2). Radiofrequency energy delivery to the entrance of the I‐ <jats:styled-content style="fixed-case">SANC</jats:styled-content> , 10.4±2.8 mm away from the <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ‐ <jats:styled-content style="fixed-case">SANRT</jats:styled-content> , terminated tachycardia immediately after onset of energy delivery (3.4±2.3 seconds). The successful ablation site was located further from the <jats:styled-content style="fixed-case">EAAS</jats:styled-content> during sinus rhythm ( <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ‐sinus) than the <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ‐ <jats:styled-content style="fixed-case">SANRT</jats:styled-content> (12.8±4.5 versus 7.2±3.1 mm; <jats:italic>P</jats:italic> <0.0001). </jats:p> </jats:sec> <jats:sec xml:lang="en"> <jats:title>Conclusions</jats:title> <jats:p xml:lang="en"> The reentry circuit of <jats:styled-content style="fixed-case">SANRT</jats:styled-content> was composed of the entrance and exit of the I‐ <jats:styled-content style="fixed-case">SANC</jats:styled-content> being located at distinctly different anatomical sites. <jats:styled-content style="fixed-case">SANRT</jats:styled-content> was eliminated by radiofrequency energy delivered to the I‐ <jats:styled-content style="fixed-case">SANC</jats:styled-content> entrance, which was further from the <jats:styled-content style="fixed-case">EAAS</jats:styled-content> ‐sinus than I‐ <jats:styled-content style="fixed-case">SANC</jats:styled-content> exit. </jats:p> </jats:sec>