Differences Between the Unipolar Versus Bipolar Potential‐Based Activation Maps of Ventricular Premature Contractions Arising From Ventricular Outflow Tracts

Figures

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  Figure 1. This illustrates local electrogram analysis. A 12‐lead electrocardiogram of a ventricular premature contraction (VPC) with bipolar and unipolar electrograms is shown at a sweep speed of 400 mm/s. The white dotted line indicates the timing of the first rapid bipolar deflection, which was annotated manually. This corresponds to the first rapid unipolar deflection. The red dotted line indicates the QRS onset, and the yellow dotted line indicates the timing of the unipolar −dV/dTmax as determined by the automated algorithm in the mapping system. −dV/dTmax = maximal negative derivative of the extracellular unipolar potential; VPC = ventricular premature contraction.

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  Figure 2. An example of the VPC case arising from RVOT free wall where ablation resulted in immediate suppression. (A) The red arrow in the left panel indicates the earliest activation site (EAS) in the unipolar‐based activation map. The right panel shows the intracardiac signals at this EAS. The yellow dotted line in the right panel indicates the timing with −dV/dTmax determined based on the automated annotation algorithm in the mapping system. It precedes the QRS onset by 26 ms. (B) The red arrow in the left panel indicates the EAS in the bipolar‐based activation map. The right panel shows the intracardiac signals at this EAS. The white dotted line in the right panel indicates the timing of the first bipolar deflection corresponding to the first unipolar deflection. It also precedes the QRS onset by 26 ms. The EASs in both unipolar‐ and bipolar‐based activation maps are identical, which results in the distance between the two EAS of “0 mm.” EAS = earliest activation site; RVOT = right ventricular outflow tract; other abbreviations as in Figures 1 and 2.

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  Figure 3. An example of the VPC case arising from the septal RVOT where ablation resulted in delayed suppression. (A) The red arrow in the left panel indicates the EAS in the unipolar‐based activation map. The right panel shows the intracardiac signals at this EAS. The timing with the unipolar −dV/dTmax (yellow dotted line) preceded the QRS onset by 14 ms. (B) The red arrow in the left panel indicates the EAS in the bipolar‐based activation map. The right panel shows the intracardiac signals at this EAS. The first bipolar deflection (white dotted line) precedes the QRS onset by 26 ms, corresponding to the first unipolar deflection. The unipolar −dV/dTmax occurs 23 ms later than this first bipolar deflection (i.e., 3 ms ahead of the QRS onset). (C) The blue and pink tags denote the EASs in the unipolar‐ and bipolar‐based activation maps, respectively. The distance between these points was 4.5 mm. Abbreviations as in Figures 1, 2, 3.

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  Figure 4. An example of the VPC case arising from ASC where ablation resulted in immediate suppression. (A) The red arrow in the left panel indicates the EAS in the unipolar‐based activation map. The right panel shows the intracardiac signals at this EAS. The unipolar −dV/dTmax (yellow dotted line) occurred 4 ms after the QRS onset. (B) The red arrow in the left panel indicates the EAS in the bipolar‐based activation map. The right panel shows the intracardiac signals at this EAS. The first bipolar deflection (white dotted line) precedes the QRS onset by 23 ms, corresponding to the first unipolar deflection. The unipolar −dV/dTmax occurs 37 ms later than this first bipolar deflection (i.e., 14 ms later than the QRS onset). (C) The blue and pink tags denote the EASs in the unipolar‐ and bipolar‐based activation maps, respectively. The distance between these points is 16.8 mm. ASV = aortic sinus of Valsalva; NC = non‐coronary; other abbreviations as in Figures 1, 2, 3.

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  Figure 5. Distribution of the distance between EASs in the unipolar‐ and bipolar‐based maps between ASC versus non‐ASC origin VPCs. Abbreviations as in Figures 2 and 3. *Remained significant with a Bonferroni correction (p < 0.0083).

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  Figure 6. Distribution of the distance between EASs in the unipolar‐ and bipolar‐based maps depending on the successful ablation site. Abbreviations as in Figures 2 and 3. *Remained significant with a Bonferroni correction (p < 0.0083). **p < 0.001.