1. Volume 11, Issue 1, Pages 26-33 (January 2014)
Transthoracic epicardial ablation of mitral isthmus for treatment of recurrent perimitral flutter 
Antonio Berruezo, MD, PhD, Felipe Bisbal, MD, Juan Fernández-Armenta, MD, Naiara Calvo, MD, PhD, José Ángel Cabrera, MD, PhD, Damián Sanchez-Quintana, MD, PhD, David Andreu, MSc, Teresa M. de Caralt, MD, PhD, Josep Brugada, MD, PhD, Lluís Mont, MD, PhD 
Heart Rhythm 
Volume 11, Issue 1, Pages (January 2014)
DOI: /j.hrthm
Copyright © 2014 Heart Rhythm Society Terms and Conditions

2. Figure 1
Top: Left anterior oblique view of the epicardial activation map of perimitral flutter (left) and 12-lead ECG during tachycardia (right). Bottom: Entrainment from the proximal electrodes of the coronary sinus (CS). Pacing intervals, postpacing interval, and tachycardia cycle length are shown. Electrodes p-2 to 3-4 are positioned in high right atrium (RA), 5-6 to 7-8 in the lower lateral RA, 9-10 in the cavotricuspid isthmus, and to 19-d in the proximal to distal CS.
Heart Rhythm  , 26-33DOI: ( /j.hrthm )
Copyright © 2014 Heart Rhythm Society Terms and Conditions

3. Figure 2
Anatomic description of the transthoracic epicardial ablation. A: Activation mapping of perimitral flutter (PMF) projected on the left atrial computed tomographic reconstruction (anterior view). PMF persists after endocardial ablation of the mitral isthmus (MI; red dots). B: Left anterolateral projection of cardiac computed tomography of the same patient showing the epicardial aspect of the MI and location of the coronary sinus and circumflex coronary artery (arrowhead) at the AV groove. C: Same projection showing the epicardial bipolar voltage map after endocardial ablation of the MI. An incomplete line of low voltage with gaps can be seen in the epicardial MI. D: MI epicardial ablation line. Note the presence of low-voltage fractionated electrograms (asterisk in upper panel) at the site of the line gaps. Ablation at this site interrupted the tachycardia.
Heart Rhythm  , 26-33DOI: ( /j.hrthm )
Copyright © 2014 Heart Rhythm Society Terms and Conditions

4. Figure 3
Right (A) and left (B) posterolateral views of the projected voltage map showing a low-voltage area at the mitral isthmus, where prior endocardial radiofrequency ablation lesions were delivered. Low-voltage fractioned electrograms are tagged with pink dots along the epicardial mitral isthmus, suggesting a nontransmural endocardial ablation line. C: Surface ECG leads II and V6 and recordings from the ablation (Map) and duodecapolar catheters (proximal, p-2 to distal, 19-d). Note the presence of low-voltage electrogram recorded by the ablation catheter at the epicardial ablation line.
Heart Rhythm  , 26-33DOI: ( /j.hrthm )
Copyright © 2014 Heart Rhythm Society Terms and Conditions

5. Figure 4
Top: Posteroanterior X-ray projection (left) showing a duodecapolar catheter at the coronary sinus (CS) and the ablation catheter at the endocardial aspect of the mitral isthmus (MI) (Map). Note the presence of the sheath in the pericardial space (arrowhead). Left anterior oblique (LAO) projection (right) showing the ablation catheter at the epicardial aspect of the MI. Bottom: Surface ECG (I-III-V5) and intracardiac recordings of the mapping (Map) and duodecapolar catheter (proximal, p-2 to distal, 19-d). Pacing (asterisk) from proximal CS demonstrates conduction through the MI before epicardial ablation (A). Bidirectional conduction block is demonstrated when pacing from both sites of the MI line (B, C). Note the presence of double potentials at the site of the MI line (arrows). PA = posteroanterior.
Heart Rhythm  , 26-33DOI: ( /j.hrthm )
Copyright © 2014 Heart Rhythm Society Terms and Conditions

6. Figure 5
A: Surface ECG (II) and intracardiac recordings of the ablation (Abl) and duodecapolar catheter (proximal, p-2 corresponds to RA; 3-4 to 19-d corresponds to proximal to distal coronary sinus) showing the presence of a counterclockwise perimitral flutter (same patient as in Figure 4). Note that left atrial activation recorded from the coronary sinus electrodes covers almost the complete cycle length of the tachycardia. Double potentials (arrowheads) were recorded from the dipole corresponding to the mitral isthmus line. Epicardial radiofrequency delivery at the mitral isthmus between the coronary sinus and the inferior pulmonary vein terminated the tachycardia (only the first double-potential component is observed in 11-12). Note also the noise in the Abl electrode during radiofrequency ablation B: Surface recording showing a 6-second asystole after perimitral flutter termination.
Heart Rhythm  , 26-33DOI: ( /j.hrthm )
Copyright © 2014 Heart Rhythm Society Terms and Conditions