Feasibility of electroanatomic mapping and radiofrequency catheter ablation in Boxer dogs with symptomatic ventricular tachycardia

Figures

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  FIGURE 1. Pace mapping of ventricular tachycardia in a Boxer using the PASO module on the CARTO system. The native rhythm (green) is shown on a 12‐lead surface ECG at 200 mm/s, and consists of ventricular tachycardia with a left bundle branch block morphology and inferior axis. The paced rhythm (yellow) is superimposed onto the native rhythm starting at the third complex and the PASO module calculated the correlation between paced and native QRS morphologies in each lead. For example, in lead I, the correlation is 0.971, or 97.1%. An overall correlation percentage is shown at the top of the figure, illustrating 0.979 or 97.9% concordance at this paced location. Radiofrequency catheter ablation was subsequently performed at this site

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  FIGURE 2. Bipolar voltage mapping of the right ventricle (RV) and the left ventricle (LV) in 2 Boxers during sinus rhythm. The voltage signals of intracardiac EGMs are displayed in the RV and LV. Red represents voltages that are ≤0.5 mV and purple represents voltages that are ≥1.5 mV. Intermediate ranges are represented on a color scale as displayed in the top left corner of the figures. Regions with voltages <1.5 mV are consistent with electroanatomic scar, whereas regions with voltages >1.5 mV are consistent with normal conducting myocardium. The voltage mapping density was sufficient to allow detailed endocardial surface geometric reconstruction with a fill threshold ≤10 mm. A, This Boxer had evidence of electroanatomic scar at the endocardial surface of the right ventricular outflow tract (RVOT). B, This Boxer had no evidence of electroanatomic scar; the minor color changes represent ablation sites and perivalvular structures. Bi, bipolar

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  FIGURE 3. Activation mapping of a ventricular premature complex (VPC) in a Boxer with a focal activation pattern. A, The surface ECG appearance of a VPC is shown at the top (white trace) at 200 mm/s, and an intracardiac electrogram (EGM) of the same VPC at the septal aspect of the right ventricular outflow tract (RVOT) is shown below (blue trace). The vertical yellow dotted line marks the earliest appearance of the EGM, whereas the vertical red line marks a reference time (time 0 s) at the peak of the R wave on the surface ECG. The intracardiac EGM occurs 16 ms before the onset of the QRS complex in the surface ECG and approximately 98 ms before the reference time, demonstrating that the location of the mapping catheter is at or near the site of earliest activation. B, An isochronal map is shown in the right ventricle, demonstrating centrifugal activation of the same VPC from a focal site at the septal RVOT. Each individual point signifies the earliest activation time of a local EGM, represented by a color that covers an area up to 15 mm away. These local activation times (LATs) are signified by layers of different colors, with the earliest activation (−98 ms) represented in red and the…