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What is QRS duration greater than 0.16 seconds is seen in? and explain in detail?
ANSWER: (A) Bundle branch blocksREF: Harrisons 18th ed chapter 228, Practical Clinical Electrophysiology by Peter J. Zimetbaum,Mark E. Josephson Page 143Normal QRS duration: 0.06 - 0.1 secondsRAISED QRS DURATION IS SEEN IN:Ventricular tachycardia (Assume any wide QRS-complex tachycardia is VT until proven otherwise)Right bundle branch blocks (up to 0.14 sec)Right bundle branch blocks with VT (> 0.14 sec)Left bundle branch blocks (up to 0.16)Left bundle branch blocks with VT(> 0.16)Intraventricular block (as seen in Hyperkalemia, quinidine, procainamide)Implanted ventricular pacemakerNOTE: * Mobitz I heart block (Type 1 Second-degree AV block) is characterized by progressive prolongation of the PR interval on the electrocardiogram (BCG) on consecutive beats followed by a blocked P wave (i.e., a 'dropped' QRS complex). After the dropped QRS complex, the PR interval resets and the cycle repeats.* Mobitz II heart block (Type 2 Second-degree AV block) is characterized on a surface ECG by intermittently non conducted P waves not preceded by PR prolongation and not followed by PR shortening