3 Standardization Standardization mark 10 mm vertical deflection = 1 mVolt
4 Rate Ventricular rate (heart rate) Atrial rate 3rd degree AV block RR intervalAtrial ratePP interval3rd degree AV block
5 Heart Rate Calculation 1500 divided by the number of small boxes between two R wavesmost accuratetake time to calculateonly use with regular rhythms1 lg sq = 300 bpm2 lg sq = 150 bpm3 lg sq = 100 bpm4 lg sq = 75bpm5 lg sq = bpm6 lg sq = bpm300 divided by the number of large boxes between two R wavesquicknot too accurateonly use with regular rhythm10 multiplied by the number of R waves in 6 secondsless preciseuse with irregular rhythmsvery quick
6 Rhythm Sinus rhythm - consistent P waves Atrial rhythm - irregular P wavesJunctional/Nodal rhythm - no P waves, late P waves, or inverted P wavesVentricular rhythm - no P waves, wide QRS
7 AV Junctional RhythmsRetrograde P waves immediately preceding the QRS complexes in aVR and II.Retrograde P waves immediately following the QRS complexesAbsent P waves
8 ECG Waves P wave atrial depolarization ≤ 2.5 mm in amplitude < 0.12 sec in widthPR interval ( sec.)time of stimulus through atria and AV nodeprolonged interval = first-degree heart block
16 Q Waves Abnormal if wider than 0.04 sec Greater than 25% of the R wave Leads I, II, III, aVf or leads V3 - V6.Greater than 25% of the R waveNote: Not all Q waves are abnormal, Not all Q waves are the result of MI.
17 QRS WidthWideRBBB or LBBBPremature ventricular beatsWPW
22 Transmural MI Pathalogical Q waves ST segment elevation. IschemiaTall T waves(and/or reciprocal T wave inversion)InjuryST segment elevation.T wave inversion of the previously tall T wavesInfarctPathalogical Q waves(at least one small box wide or 11/3 the entire QRS height)
23 Posterior (reciprocal) OverviewLEADAREA OF THE HEARTV1-V2Anterior/SeptumV3-V4Anterior WallV5-V6Anterior/LateralII, III, aVFInferiorI and aVLLateralPosterior (reciprocal)
24 ST Segments J point: end of QRS wave beginning of ST segment beginning of ventricular repolarizationnormally isoelectric (flat)changes, elevation or depression, may indicate pathological condition
25 Subendocardial Ischemia ST segment depression criteria1 mm or morehorizontal or downwardlasts 0.08 secondsdepression of only the J point with rapid upward sloping are considered normal.