<prompt> QRS duration greater than 0.16 seconds is seen in?Bundle branch blockSick sinus syndromeMobitz 1Mobitz 2  <response>: 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 otherwiseRight bundle branch blocks up to 0.14 secRight bundle branch blocks with VT 0.14 secLeft bundle branch blocks up to 0.16Left bundle branch blocks with VT 0.16Intraventricular block as seen in Hyperkalemia, quinidine, procainamideImplanted 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 