Figure legends:
Fig 1: Body surface ECG (I, II and V1) and intracardiac electrograms during sinus rhythm (sinus cycle length, 1000 ms) (A) and during pacing from the distal coronary sinus (pacing cycle length, 600 ms) (B) at a sweep speed of 25 mm/s (A-1/B-1) and 100 mm/s (A-2/B-2).
RA indicates right atrium; LSPV, left superior pulmonary vein; CS p/m/d, proximal/mid/distal coronary sinus; CL, cycle length.
Fig 2: Body surface ECG (I, II and V1) and intracardiac electrograms during pacing from the distal coronary sinus (pacing cycle length, 750 ms) at a sweep speed of 25 mm/s (A) and 50 mm/s (B).
RA indicates right atrium; LSPV, left superior pulmonary vein; CS p/m/d, proximal/mid/distal coronary sinus; CL, cycle length.
Fig 3: (A) Body surface ECG (I, II and V1) and intracardiac electrograms during pacing from the distal coronary sinus [pacing cycle length (CL), 750 ms] at a sweep speed of 150 mm/s. Arrows indicate the earliest pulmonary vein (PV) potential of each beat. Asterisks represent far-field signal from adjacent left atrial appendage. The numbers denote cycle length (ms).
RA indicates right atrium; LSPV, left superior pulmonary vein; CS p/m/d, proximal/mid/distal coronary sinus; CL, cycle length.
(B) Proposed mechanism of the intra-PV reentry causing the echoes.
Pink areas indicate atrial myocardium or myocardial sleeves. Purple areas represent slow conduction zones. LA denotes left atrium.