Korean Circ J.  2016 Jan;46(1):56-62. 10.4070/kcj.2016.46.1.56.

Visualization of the Critical Isthmus by Tracking Delayed Potential in Edited Windows for Scar-Related Ventricular Tachycardia

• Kim JY
• Shin WS
• Kim TS
• Kim SH
• Kim JH
• Jang SW
• Pak HN
• Nam GB
• Lee MY
• Rho TH
• Oh YS

• KMID: 2223770
• DOI: http://doi.org/10.4070/kcj.2016.46.1.56

Abstract

BACKGROUND AND OBJECTIVES
Identifying the critical isthmus of slow conduction is crucial for successful treatment of scar-related ventricular tachycardia. Current 3D mapping is not designed for tracking the critical isthmus and may lead to a risk of extensive ablation. We edited the algorithm to track the delayed potential in order to visualize the isthmus and compared the edited map with a conventional map.
SUBJECTS AND METHODS
We marked every point that showed delayed potential with blue color. After substrate mapping, we edited to reset the annotation from true ventricular potential to delayed potential and then changed the window of interest from the conventional zone (early, 50-60%; late, 40-50% from peak of QRS) to the edited zone (early, 80-90%; late, 10-20%) for every blue point. Finally, we compared the propagation maps before and after editing.
RESULTS
We analyzed five scar-related ventricular tachycardia cases. In the propagation maps, the resetting map showed the critical isthmus and entrance and exit sites of tachycardia that showed figure 8 reentry. However, conventional maps only showed the earliest ventricular activation sites and searched for focal tachycardia. All of the tachycardia cases were terminated by ablating the area around the isthmus.
CONCLUSION
Identifying the channel and direction of the critical isthmus by a new editing method to track delayed potential is essential in scar-related tachycardia.

Keyword

Electroanatomical mapping; Delayed potential; Scar-related ventricular tachycardia

MeSH Terms

Tachycardia
Tachycardia, Ventricular*

Figure

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  Fig. 1 12-lead ECG of clinical VT and that of VT that was induced and targeted during the induction study. Nonclinical VT showed different axis and cycle lengths. VTs that were documented in the ICD electrograms showed similar cycle lengths and could not be terminated by anti-tachycardial pacing. ECG: electrocardiogram, VT: ventricular tachycardia, ICD: implantable cardioverter-defibrillator.

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  Fig. 2 Editing the annotation and the window of interest. (A) In conventional mapping, annotation was set to the maximum ventricular potential (arrow), and the window of interest was set to 5:5. (B) After we reset the conventional map, annotation was set to the local delayed potential (arrow), and the window of interest was reset to 9:1.

• 

  Fig. 3 Voltage map showing the locations of delayed potentials (AP view). Blue dots denote delayed potentials, which are noted along the scar border zone. Tracing of the diastolic potentials (black arrow) and entrainment of the exit and bystander sites were shown. Entrainment showed concealed fusion. AP: anterior-posterior, S-QRS: stim to QRS, PPI: post-pacing interval, VTCL: ventricular tachycardia cycle length.

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  Fig. 4 Activation map before (A) and after (B) editing. Voltage map showing the locations of the delayed potentials (C). Delayed potentials are tagged with blue dots, and scar sites are tagged with grey dots. After editing, the activation map shows the area where the early zone meets the late zone, which represents the reentry mechanism.

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  Fig. 5 Propagation map before (A) and after (B) editing. Delayed potentials are tagged with blue dots, and scar sites are tagged with grey dots. The white arrow shows the direction of propagation. (A) from apex to base; (B) figure 8 reentry through the isthmus.

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