Visualization of Critical Isthmus by Delayed Potential Mapping

Transcription

1 Visualization of Critical Isthmus by Delayed Potential Mapping Yong-Seog Oh, MD, PhD Cardiovascular Center, Seoul St. Mary s Hospital, Catholic University of Korea ABSTRACT A 57-year-old man was admitted to our institution with frequent implantable cardioverterdefibrillator (ICD) shock. The ICD was implanted for aborted sudden cardiac death due to nonischemic cardiomyopathy. Recurrent ventricular tachycardia (VT) was suspected, so an electrophysiological study was performed. Four types of VT were induced and delayed potential mapping visualized a critical isthmus. Successful ablation was performed and VT was no longer induced. Key words: 3D mapping ablation delayed potential ventricular tachycardia Introduction Many patients with structural heart disease have hemodynamically unstable ventricular tachycardia (VT). If hemodynamically stable, mapping can be performed. Conventional stable VT mapping consists of voltage mapping for defining scar, 1 electrogram mapping for characterizing the slow conduction zone, and entrainment/pace mapping for isthmus mapping. Mapping systems recreate the geometry of the ventricles using point-by-point sampling. Received: November 9, 2013 Revision Received: December 20, 2013 Accepted: December 27, 2013 Correspondence: Yong-Seog Oh MD, PhD, Director of Electrophysiology Division of Cardiovascular Medicine, Seoul St. Mary's Hospital, Catholic University of Korea, College of Medicine, 505, Banpo-Dong, Seocho-Ku, Seoul, Korea ( ) Tel : Fax : E mail : oys@catholic.ac.kr Here, we present activation mapping guided by delayed potentials, which facilitate simultaneous visualization of a slow conduction zone and isthmus/ exit mapping. Case Report A 57-year-old man presented to our institution with frequent implantable cardioverter-defibrillator (ICD) shock. He had undergone an ICD implantation 12 months previously for the treatment of syncope with non-ischemic cardiomyopathy (ejection fraction, 19%). We performed an electrophysiological study. Four types of VT were induced (Figure 1) using a magnetic navigation system (Noibe ). During the ongoing VT, the patient was hemodynamically stable and activation mapping was performed. De- 40 The Official Journal of Korean Heart Rhythm Society

2 layed potentials observed on the scar guided the activation mapping (Figure 2). A comparison of conventional mapping and our method is shown in Figures 3 and 4. Radiofrequency energies were applied to the critical isthmus and the scar border. No subsequent VT was induced. A B C D Figure 1. Four types of ventricular tachycardia were induced. In analysis of ICD EGM, (A) was culprit VT inducing ICD shock. Figure 2. Sequence of delayed potential represents direction of ongoing ventricular tachycardia. VOL.14 NO.4 41

3 Pre-Editing Post Editing Window Of Interest setting: -175 ms ~ 175 ms (5:5) Window Of Interest setting: -320 ms ~ 30 ms (9:1) Red arrow: tracking true ventricle potential Red arrow: tracking double potential Figure 3. Tracking point and window of interest set. Pre-Editing Figure 4. Activation mapping result (continued on the next page). 42 The Official Journal of Korean Heart Rhythm Society

4 Post Editing Pre-Editing White arrow shows the direction of propagation: from apex to base Post Editing White arrow shows the direction of propagation: figure 8 reenty through isthmus Figure 4. (continued) Activation mapping result. VOL.14 NO.4 43

5 Entrance Outer loop Exit Bystander us thm al is ntr e C Scar Inner loop Bystander Bystander Outer loop Figure 5. Scheme of visualization of critical isthmus by delayed potential mapping. In edited CARTO propagation map, upper to low points showed entry, isthmus and exit site sequentially. When we ablated those points, VT was terminated. site (Figure 5). Discussion References Conventional mapping, which usually consists of voltage mapping, defining delayed potentials, and entrainment mapping, requires VT stability and considerable mapping time. The presence of a delayed potential is referred to as an isthmus. 2,3 As such, sequential mapping can reveal the critical isthmus, the exit of which is located in the end. Our method simultaneously applied activation mapping and delayed potential mapping, and allowed visualization of the critical isthmus and exit 44 The Official Journal of Korean Heart Rhythm Society 1. Marchlinski FE, Callans DJ, Gottlieb CD, Zado E. Linear ablation lesions for control of unmappable ventricular tachycardia in patients with ischemic and nonischemic cardiomyopathy. Circulation. 2000;101: de Chillou C, Lacroix D, Klug D, Magnin-Poull I, Marquie C, Messier M, Andronache M, Kouakam C, Sadoul N, Chen J, Aliot E, Kacet S. Isthmus characteristics of reentrant ventricular tachycardia after myocardial infarction. Circulation. 2002;105: Bogun F, Kim HM, Han J, Tamirissa K, Tschopp D, Reich S, Elmouchi D, Igic P, Lemola K, Good E, Oral H, Chugh A, Pelosi F, Morady F. Comparison of mapping criteria for hemodynamically tolerated, postinfarction ventricular tachycardia. Heart Rhythm. 2006;3:20 26.

6 VOL.14 NO.4 45