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Wide and narrow QRS tachycardias: What is the mechanism?
Krishna Kumar Mohanan Nair1, Narayanan Namboodiri1, Ajitkumar Valaparambil1
1Department of Cardiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, 695011, India.
Abstract:
A 50-year-old lady was referred for radiofrequency catheter ablation of narrow QRS tachycardia that was terminated with intravenous adenosine. Twelve-lead Electrocardiogram (ECG) was normal during sinus rhythm. The electrophysiological study showed an Atrio-Hisian (AH) interval of 104 ms and Hisio-Ventricular (HV) interval of 45 ms during sinus rhythm. Atrial pacing reproducibly induced regular broad (left bundle branch block morphology) and narrow QRS tachycardias. A spontaneous premature ventricular ectopic from right ventricular apex has resulted in transition of the tachycardia from wide to narrow. What are the likely mechanisms?
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