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Narrow QRS Tachycardia with Transition: What Is the Mechanism?
Krishna Kumar Mohanan Nair1, Narayanan Namboodiri2, Bharatraj Banavalikar1
1Department of Cardiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India.
Abstract:
A 50-year-old woman underwent radiofrequency catheter ablation of narrow QRS tachycardia that was terminated with intravenous adenosine. Twelve-lead electrocardiogram was normal during sinus rhythm. The electrophysiological study showed normal atriohisian and hisioventricular intervals during sinus rhythm. Atrial burst pacing reproducibly induced two narrow QRS tachycardias. Figure 1 shows spontaneous switch of tachycardia 1 to tachycardia 2. What are the likely mechanisms of the tachycardia and the transition?
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