Circulation. 2007;115:e418-e421
doi: 10.1161/CIRCULATIONAHA.106.673855
(Circulation. 2007;115:e418-e421.)
© 2007 American Heart Association, Inc.
Images in Cardiovascular Medicine |
Percutaneous Epicardial Mapping and Ablation of a Posteroseptal Accessory Pathway
Ivan Ho, MD;
Andre d’Avila, MD;
Jeremy Ruskin, MD;
Moussa Mansour, MD
From the Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Mass.
Correspondence to Moussa Mansour, MD, Cardiac Arrhythmia Service and Cardiac Unit, Massachusetts General Hospital, 55 Fruit St, Gray 109, Boston, MA 02114. E-mail mmansour{at}partners.org
A 20-year-old man with no past medical history experienced a syncopal episode. He was found to be pulseless, and cardiopulmonary resuscitation was initiated. When emergency medical service arrived, rhythm strip showed an irregular wide-complex tachycardia consistent with preexcited atrial fibrillation with cycle length as short as 180 ms (333 beats per minute) (Figure 1A). He was defibrillated successfully into sinus rhythm. A 12-lead ECG showed sinus rhythm with PR interval of 110 ms, delta waves and pseudo-infarct pattern in the inferior leads consistent with a posteroseptal accessory pathway (Figure 1B). He was referred to us for an electrophysiology study.
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Figure 1. A, Rhythm strip of patient during the cardiac arrest, showing irregular wide-complex tachycardia very suggestive of preexcited atrial fibrillation. B, 12-lead ECG after resuscitation. The short PR interval, delta wave and pseudo-infarct pattern in the inferior leads are consistent with the presence of a manifest accessory pathway (Wolff-Parkinson-White Syndrome).
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During the procedure, extensive mapping in the right atrium, the coronary sinus (CS) and its branches, and the left atrium (via transseptal approach) was performed. A CS angiogram showed the presence of a diverticulum. The area of earliest ventricular activation was localized to the posteroseptal region in the proximal CS near the os. Radiofrequency applications in this area failed to eliminate the preexcitation pattern on surface ECG. At this point, a cryoablation catheter was used to create more lesions in the proximal CS, but these applications were also unable to eliminate preexcitation. At the end of this initial procedure, the accessory pathway remained intact.
The patient returned to the electrophysiology laboratory 1 week later for a repeat mapping and ablation procedure. Subxiphoid percutaneous epicardial access was obtained, and extensive endocardial and epicardial mapping was performed. The earliest ventricular activation was mapped to the epicardial surface in the posteroseptal region (Figure 2B through 2D). Preprocedural computed tomographic imaging of the heart demonstrated the course of the right coronary artery and its branches along the inferoposterior surface (Figure 2A). Because of the epicardial ablation target, a coronary angio-gram was performed to ensure that the ablation catheter was not in close proximity to one of the epicardial coronary arteries (Figure 2B). The accessory pathway was eliminated after 6.5 seconds of radiofrequency application (25 Watts, maximum temperature 44°C) in the area (Figure 3).
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Figure 2. A, Posterior-anterior projection of the heart by computed tomographic imaging integrated with CARTO-MERGE electroanatomic mapping system (Biosense Webster, Diamond Bar, Calif.), with all four chambers and the thoracic aorta shown. The 2 red circles, indicated by white arrows, depict ablation lesions that successfully eliminated the preexcitation. LA indicates left atrium; RA, right atrium; LV, left ventricle; RV, right ventricle; and Ao, aorta. B, Posterior-anterior projection of the heart by computed tomography with three-dimensional reconstruction. The white arrow shows the right coronary artery and the black arrow shows the posterior descending artery, demonstrating the potential close proximity of the ablation target to the epicardial coronary vessels. C, Left anterior oblique fluoroscopic projection of the intracardiac and epicardial catheters. The right coronary artery was opacified by contrast injection, and the distal right coronary artery (blue arrow) was separated by at least 5 mm away from the ablation catheter (yellow arrow). White arrow indicates coronary sinus decapolar catheter; black arrow, transseptal sheath with a quadripolar catheter resting in the left inferior pulmonary vein; red arrow, right atrial quadripolar catheter; and dashed arrow, right coronary catheter. D, Right anterior oblique fluoroscopic projection of intracardiac and epicardial catheters. Asterisk indicates ablation catheter; white arrow, coronary sinus decapolar catheter; black arrow, quadripolar catheter resting in the left inferior pulmonary vein; and red arrow, right atrial quadripolar catheter.
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Figure 3. Intracardiac electrograms during epicardial ablation. On the left panel, a sharp potential preceding ventricular depolarization was noted on the ablation catheter at a site of early ventricular activation, likely representing an accessory pathway potential. On the right panel, black arrows denote the disappearance of delta wave after 6.5 seconds of ablation at that location. The atrioventricular interval measured in the coronary sinus catheter was also markedly lengthened from 65 ms to 106 ms (red arrows), implying loss of accessory pathway anterograde conduction. The bottom panel shows the persistent disappearance of preexcitation during the same RF application (recorded at 50 mm/s speed). A indicates atrial signal; V, ventricular signal; AP, accessory pathway potential; ABL d, distal channel of the ablation catheter; CS p, proximal channel of the coronary sinus catheter (CS 9 to 10); CS d, distal channel of the coronary sinus catheter (CS 1 to 2); and RF, radiofrequency application.
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Successful epicardial mapping and ablation of difficult accessory pathways have been previously reported,1–4 with the majority being in the posteroseptal area. Because of the thickness of the myocardium in this area, energy delivered from endocardial ablation often may not reach the epicardial location of the accessory pathway. In this case, the epicardial ablation lesions were clearly at a distance away from the sites of attempted endocardial ablation (Figure 4A and 4B). For this reason, epicardial approach should be considered when repeated attempts of endocardial ablation fail to terminate accessory pathway conduction.
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Figure 4. A, Superior ("top-down") view of the computed tomography image of the heart (with the right and left atria removed). The white arrow denoted points marked at areas of earliest ventricular activation during epicardial mapping. Note the distance away from the coronary sinus where endocardial ablations were previously attempted (red arrow). RV indicates right ventricle; LV, left ventricle. B, Right lateral projection of the computed tomography image of the heart. Again noted is the distance of the ablation lesions (white arrows) from the posteroseptal region (red arrow) targeted by the endocardial approach. RA indicates right atrium; RV, right ventricle.
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Disclosures
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None.
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References
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3. de Paloa AA, Leite LR, Mesas CE. Nonsurgical transthoracic epicardial ablation for the treatment of a resistant posteroseptal accessory pathway. Pacing Clin Electrophysiol. 2004; 27 (2): 259–261.[CrossRef][Medline]
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4. Sapp J, Soejima K, Couper GS, Stevenson WG. Electrophysiology and anatomic characterization of an epicardial accessory pathway. J Cardiovasc Electrophysiol. 2001; 12 (12): 1411–1414.[CrossRef][Medline]
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References