1. HeartRhythm Case Reports
Complex organized atrial arrhythmia with alternation between two circuits involving probable epicardial connections: An ultra-high-density mapping study 
Ghassan Moubarak, MD, Alexandre Zhao, MD, Olivier Thomas, MD, Bruno Cauchemez, MD 
HeartRhythm Case Reports 
DOI: /j.hrcr
Copyright © 2019 Heart Rhythm Society Terms and Conditions

2. Figure 1
Tuning of the Rhythmia (Boston Scientific, Marlborough, MA) settings. A: The 2 alternating cycle lengths (CL) with different activation patterns on the coronary sinus catheter. B: The CL graph with a sawtooth pattern and the 2 activations mapped separately: in green, the lower points corresponding to the short CL of 519 ms (circuit 1); and in blue, the upper points corresponding to the long CL of 665 ms (circuit 2). C: For both circuits, the voltage map is shown with the nominal confidence mask at 0.03 mV and at the lowest possible value of 0.01 mV, which was required to understand the activation.
HeartRhythm Case Reports DOI: ( /j.hrcr )
Copyright © 2019 Heart Rhythm Society Terms and Conditions

3. Figure 2
Activation mapping of circuit 1 and circuit 2. Sequential activation propagation is annotated by numbers. The missing endocardial activation is between points 8 and 9 (connecting circuit 1 to circuit 2) and between points 15 and 1 (connecting circuit 2 back to circuit 1). Local electrograms along the circuits are displayed.
HeartRhythm Case Reports DOI: ( /j.hrcr )
Copyright © 2019 Heart Rhythm Society Terms and Conditions

4. Supplemental Figure 1
12-lead ECG. The ECG of the tachycardia (Panel A) and particularly lead V1 of the Rhythmia screen (panel B) which best delineated the P wave. The slope of the P wave corresponding to Circuit 1 showed a plateau phase (arrow) while it was continuously rising in Circuit 2.
HeartRhythm Case Reports DOI: ( /j.hrcr )
Copyright © 2019 Heart Rhythm Society Terms and Conditions

5. Supplemental Figure 2
Circuit 1. Panels A to D show the activation step-by-step of Circuit 1. Starting from the lower ridge, one wavefront propagates superiorly then around the posterior aspect of the left pulmonary vein (PV) antrum, and a second wavefront propagates towards the distal coronary sinus then joins the first wavefront at the level of the lower inferior PV. Note the wide complex fractionated electrogram at the lower ridge level.
HeartRhythm Case Reports DOI: ( /j.hrcr )
Copyright © 2019 Heart Rhythm Society Terms and Conditions

6. Supplemental Figure 3
Missing endocardial activation between the end of Circuit 1 and the start of Circuit 2.
HeartRhythm Case Reports DOI: ( /j.hrcr )
Copyright © 2019 Heart Rhythm Society Terms and Conditions

7. Supplemental Figure 4
Circuit 2. Panels A to D show the activation step-by-step of Circuit 2. Activation from the posterior wall proceeds inferiorly, turns around the left inferior pulmonary vein (LIPV), enters the LIPV at its anterior pole and ends at the posterior aspect of the LIPV.
HeartRhythm Case Reports DOI: ( /j.hrcr )
Copyright © 2019 Heart Rhythm Society Terms and Conditions

8. Supplemental Figure 5
Missing endocardial activation between the end of Circuit 2 and the start of Circuit 1.
HeartRhythm Case Reports DOI: ( /j.hrcr )
Copyright © 2019 Heart Rhythm Society Terms and Conditions

9. Supplemental Figure 6 Atrial tachycardia termination.
HeartRhythm Case Reports DOI: ( /j.hrcr )
Copyright © 2019 Heart Rhythm Society Terms and Conditions

10. Supplemental Figure 7
Alternative mechanism: ligament of Marshall-mediated focal atrial tachycardia with alternation of unidirectional conduction block.
HeartRhythm Case Reports DOI: ( /j.hrcr )
Copyright © 2019 Heart Rhythm Society Terms and Conditions