If AV valves are closing before iso-volumetric contraction why S1 is being shown after QRS complex (which is coinciding with iso-volmetric contraction). Shouldn’t it be heard at the start of QRS complex or before ? Kindly clear my doubt
Depolarisation (sodium channels open/stage 0-sodium getting in=QRS) contraction(due to calcium influx stage 2) therefore depolarisation occurs first and contraction occurs next