<prompt> P wave in ECG is due to :Ventricular depolarizationAtrial repolarizationVentricular repolarizationAtrial depolarization  <response>: Ans. d Atrial depolarizationECG findingSignificanceP waveAtrial DepolarizationQRSVentricular depolarizationT waveVentricular repolarizationU waveDelayed repolarization of papillary musclesPR intervalSpread of impulse from SAN to AVNST segmentIso-electric segment 