AF Inducibility Is Related to Conduction Abnormalities at Bachmann’s Bundle

Figures

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  Figure 1. Mapping procedure and signal annotation. (a) Epicardial mapping scheme designed to cover the entire atria. (b) The steepest negative deflection of each atrial potential, indicated by the red cross, was marked as the LAT. (c) Color-coded activation map of a sinus rhythm beat, reconstructed by using LATs. Isochrones are drawn at 10 ms intervals and the arrow indicates the main direction of propagation. A: atrial potential, BB: Bachmann’s bundle, ICV: inferior vena cava, LA: left atrium, LAT: local activation time, PV: pulmonary veins, RA: right atrium, SCV: superior vena cava, V: ventricular far-field potential.

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  Figure 2. Maximum length of lines of conduction block. (a) The longest line of CB for each individual patient in the NI (green markers) and susAF group (red markers). Lines of CB longer than 28 mm were only found in the susAF group, occurring in 35% of the susAF group. (b) Three color-coded activation maps in which orientation and length of lines of CB are demonstrated. The upper map shows only 2 short lines of CB (4 and 2 mm, magnitude: each 13 ms), whereas lengths up to 22 mm (magnitude: 27 ms) and 40 mm (magnitude 46 ms) are observed in the middle and lower activation maps, respectively. Thick black lines indicate lines of CB. CB: conduction block, NI: non-inducibility, SusAF: sustained atrial fibrillation.

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  Figure 3. Total activation time of Bachmann’s bundle. (a) Increasingly complex patterns of activation observed in three patients with different TATs, ranging from 37 ms (upper) to 143 ms (lower). (b) Boxplot of TAT for each individual patient in the NI and susAF groups. Compared to patients from the NI group, excitation time was prolonged in susAF patients (TAT 55 m (28–143 ms) versus 46 ms (24–73 ms), p = 0.012). Arrows indicate main wavefront direction, whereas crowding of isochrones, drawn at 10 ms intervals, indicates conduction delay. BB: Bachmann’s bundle, NI: non-inducibility, SusAF: sustained AF, TAT: total activation time.

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  Figure 4. Areas of simultaneous activation. (a) Bachmann’s bundle is activated by wavefronts that enter from both the RA and LA side and are extinguished at the perimeter of an area of SimAct (dashed red lines). This SimAct area covers 41% of the mapping area. (b) Two SR wavefronts enter the RA and LA side, propagate towards the opposite side of the array along, respectively, the left and right border but remain separated by multiple areas of SimAct, covering 66% of the mapping area. Areas of SimAct are partly delineated by long lines of CB (indicated by crowding of isochrones). Isochrones are drawn at 10 ms intervals and arrows indicate main wavefront direction. CB: conduction block, LA: left atrium, RA: right atrium, SimAct: simultaneous activation, SR: sinus rhythm.

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  Figure 5. Peak-to-peak amplitudes of the unipolar potentials. (a) Relative frequency distributions of peak-to-peak amplitudes of U-EGM for the entire NI and susAF group. U-EGM amplitudes < 1 mV occurred more frequently in the susAF group (12% versus 6%). (b) Likewise, the amount of low voltages per patient was larger in the susAF group (susAF: 6 (0–77)%, NI: 1 (0–38%), p = 0.035), as illustrated by the scatterplot. NI: non-inducibility, SimAct: simultaneous activation, susAF: sustained atrial fibrillation, U-EGM: unipolar electrocardiogram.