D1-2 Normal ECG July 2024 Dip.pdf

Diploma in ECG Interpretation The Normal ECG Relationship between sequence of electrical events and ECG 1. Atrial 2. AV nodal 3. Ventricular 4. Ventricular depolarisation depolarisation depolarisation repolarisation P wave PR segment QRS complex...

Diploma in ECG Interpretation The Normal ECG Relationship between sequence of electrical events and ECG 1. Atrial 2. AV nodal 3. Ventricular 4. Ventricular depolarisation depolarisation depolarisation repolarisation P wave PR segment QRS complex T wave (c) D Richley 2022 ▪ P Wave: atrial activation Nomenclature QRS complex: ventricular activation – R wave composed of the following components, not all of which need to be present: T wave ▪ Q wave: a negative deflection which is not preceded by a positive deflection ST segment ▪ R wave: a positive deflection ▪ S wave: a negative deflection following a positive deflection ▪ T wave: ventricular recovery – may P wave be positive or negative s wave q wave ▪ U wave: Small waveform, sometimes seen after T wave, usually positive Normal U waves V1 Normally best seen V1-V4 Smaller than T wave Positive V2 V3  R wave T wave P wave S wave  R wave Q wave  Terminology R R Q s QS R’ r r r q s S S  Electrocardiographic amplitude and time scales 1 mV 40 ms 0.2 s 1.0 s Vertical scale: 1 cm = 1 millivolt Horizontal scale: 25 mm = 1 second  Waveforms and Intervals PR interval QRS Start of P wave to start duration of QRS complex Normal range = 0.12 – 0.2 s QRS duration Start of QRS complex to end of QRS complex Normal value 0.5 mV in amplitude Isoelectric ST segment (+/-0.5 mm) T wave and QRS polarities similar (not different in >1 lead) T wave amplitude 5 mm Chest leads Initial small r wave in V1, followed by a deeper S wave R:S ratio increases from V1 to V6 Dominant R in V6 No q wave V1-V3 No q wave >25% amplitude of following R-wave or >0.04 s V4-V6 At least 1 QRS >1 mV in amplitude S wave in V1 + R wave in V5 or V6 2.5 mm LA abnormality Hypertension RA abnormality MV disease Cor pulmonale Cardiomyopathy  Normal QT interval QTc 0.04s in I, II or aVF Normal, small q waves in I & II Normal ECG Abnormal Q waves due to myocardial infarction Normal QRS axis Dominant R-wave in I and II  QRS vector On balance, depolarisation of the ventricles proceeds downwards and to the left  QRS amplitudes in limb leads At least 1 QRS amplitude >0.5 mV in amplitude 1.3 mV  Normal ECG I aVR V1 V4 II aVL V2 V5 Small QRS complexes in limb V3 leads due to cardiac amyloidosis aVF V6 III Normal ST segments in limb leads Isoelectric ST segment (+/- 0.5 mm)  Normal ECG http://cdn.lifeinthefastlane.com/wp-content/uploads/2011/10/lateral-MI-1st-diagonal.jpg ST elevation in I & aVL (+ depression in III & aVF) due to acute MI Normal T in limb leads T and QRS polarities similar T wave amplitude ≤5 mm  Normal ECG Abnormal T wave inversion  T wave amplitudes in limb leads T and QRS polarities similar T wave amplitude ≤5 mm Not a hard-and-fast rule: T wave height is related to QRS height  Normal ECG Tall T waves due to hyperkalaemia 9 mm Normal QRS progression in chest leads LA LA V6 LV V5 V4 V1 V2 V3 Initial small r in V1, followed by a deeper S R:S ratio ↑ from V1 to V6 Dominant R in V6  Normal ECG Poor R wave progression due to anterior MI  Normal q waves in chest leads No q-wave V1 to V3 No q-wave >25% of following R-wave or >0.04 s V4-V6  Normal ECG Widespread Q waves due to MI  Normal QRS amplitudes in chest leads S-wave V1 + tallest R-waveV5/V6 1 mV Normal ECG Abnormally small QRS complexes chest leads Hypothyroidism Normal ST segments in chest leads No ST↑ 2 mm ≥ V2/V3; no ST↑ ≥ 1 mm other V leads No ST↓ Normal ECG ST elevation due to MI  Normal ST depression due to NSTEMI  Normal T waves in chest leads upright V2-V6 ≤5 mm in amplitude ≥10% R wave height V2-V6 Normal T waves in chest leads Upright T-waves ≤ 10 mm in height V2 to V6 Normal T wave inversion due to non-ST elevation MI NormalTTwaves Normal wavesininchest chestleads leads upright V2-V6 ≤5 mm in amplitude ≥10% R wave height V2-V6 Tall T waves due to hyperkalaemia (+ broad QRS, absent P waves, ST elevation)  Normal T waves in chest leads upright V2-V6 ≤5 mm in amplitude ≥10% R wave height V2-V6 Flat/low amplitude T waves V4-V6 (old MI)  Normal variants Deep Q in aVL Deep Q in III -ve T waves in limb leads (with –ve QRS) ‘early repolarisation’ Juvenile T wave inversion ‘Athlete’s heart’  Normal Q aVL No significance if an isolated finding Usually associated with negative P in aVL  Normal Q III Very common and of no significance if no abnormal Q in aVF too Some people advocate deep inspiration to determine whether Q is pathological. This has no validity. Normal neg T waves: T wave and QRS polarities similar  Normal T wave inversion: slight difference between T wave and QRS polarities Normal ECG: T and QRS polarities may differ in one lead  Normal ST elevation J waves Early repolarisation pattern Usually considered a benign normal variant: More frequent in athletes May be seen in healthy young adults More frequent in black people More frequent in males ‘Benign early repolarisation’ J wave J waves Most common in young, athletic & black males Upwardly concave ST segment (smiley face ) Negative T waves: juvenile pattern Normal in children from V1 to V3: T waves gradually become positive with age, often passing through a biphasic stage  2 year old male Sinus tachycardia @ 125 bpm Dominant R in V1 & V2 T wave inversion V1& V2 8 year old female T wave inversion V1 & V2 8 year old male Biphasic T in V1 Notched T in V2 T waves in transition from juvenile to adult pattern 16y male  ? persistent juvenile T wave pattern Inverted T waves occasionally seen in V1 and V2 in normal adults  Endurance runner ST elevation V2/V3 T wave inversion V1-V3 Highly trained athletes may have very abnormal ECGs …but athletes may have heart disease  Normal variant: black athlete ST elevation T wave inversion Large QRS amplitudes …but athletes may have heart disease  Normal or abnormal? If abnormal, list the abormalities 1  1 HR at upper limit of normal (100 bpm) Abnormally broad QRS (140 ms) Abnormal QRS axis: -ve QRS in lead II Deep Q wave aVF ST depression I, aVL, V5, V6 ST elevation III, aVR, aVF, V1-V4 Inverted T in I, aVL & V6 (discordant T also in II, III, aVF & aVR) Abnormally tall T waves No initial R in V1 High amplitude QRS in chest leads (SV1+RV6 > 3.5 mV) 2  2 Inverted T in I, II, aVL and V2-V6 Deep Q waves V2-V5 ST elevation V1-V4 Also: broad, blunt Q wave in aVL (similar but less pronounced in I) 3  3 Deep Q waves in II & aVF (& III) - borderline in V6 Slight ST elevation II, III, aVF, V5 & V6 ST depression in I, aVL, V2 and V3 Dominant R wave in V1 Low amplitude T waves 4  4 Inverted T in I, aVL and V4-V6 ST depression in I , aVL, V5 & V6 ST elevation V1 (+ V2/V3) High amplitude QRS in chest leads (SV1+RV6 > 3.5 mV) 5  5 HR > 100 bpm Abnormal QRS axis (-ve QRS in lead I) Tall, pointed P waves in II, III & aVF Flat or shallowly inverted T waves in II, III & aVF T wave inversion V2-V5 (& V1) No initial R wave in V1 (Q wave instead) QRS in V6 is not predominantly +ve Slight ST elevation V4 & V5 (+ V2/V3) Also: predominantly –ve P in V1, biphasic P in V2 6  6 Abnormal QRS axis (-ve QRS in leads I & II) Abnormal Q waves in I, II, aVF & V6 Discordant T waves in II & aVF Dominant R wave in V1 Abnormal R:S ratio progression in chest leads T wave inversion in V6 ST elevation in aVL and V4-V6 Also, terminal T wave inversion in V5 7  7 Normal ECG 8  8 Abnormal QRS axis (-ve QRS in lead II) Long PR interval (400 ms) 9  9 Deep Q waves in I, II, aVF and V4-V6 Relatively tall initial R wave in V1 (with 2nd small R wave) Abnormal R:S ratio progression from V1-V3 Bradycardia (55 bpm) 10  10 Abnormal QRS axis (-ve QRS in lead II) QRS/T discordance in II, III, aVF and aVR Equiphasic QRS in V6