PMC8419514_01
When atrial RS2 program stimulation reached 130 min; the wide QRS tachycardia of the left bundle branch block was induced at 259 bpm.
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F1
When the program stimulus negative scan to the combined rhythm interval was 130 ms, the S2-R interval was not significantly prolonged, and the wide QRS tachycardia of the left bundle branch block was induced at 259 bpm (Figure 1).
Wide QRS tachycardia suddenly and automatically changed to narrow QRS tachycardia. After zooming in the image and slowing down the paper speed to 50 mm/s, we measured the ECG in the esophageal lead. The RP interval was 112 ms, and the PR interval was 120 ms in wide QRS tachycardia, while the RP interval was 76 ms and the PR interval was 120 ms in narrow QRS tachycardia.
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F2
Sixteen seconds later, the tachycardia suddenly changed to a regular narrow QRS tachycardia of 306 bpm (Figure 2).
The tachycardia stopped abruptly after the atrium was captured by eight overdrive stimuli with a frequency of 350 bpm.
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F3
After capturing the atria with eight overspeed stimuli with a frequency of 350 bpm, the tachycardia suddenly stopped (Figure 3).