The document provides an overview of electrocardiography (ECG/EKG) including its uses in diagnosis, components of an ECG reading, normal values, abnormalities, and interpretations. Key aspects of ECG such as P waves, QRS complex, ST segment, T wave, and measurements including axes are defined. Common conditions involving the heart's rhythm and structure that can be identified on ECG are also summarized.

1. Electrocardiogram Lilong Tang M.D., Ph.D Department of Cardiology The First Affiliated Hospital Sun Yat-sen University

3. ECG ( EKG ) is Useful in the Diagnosis of Different kinds of arrhythmia; Enlargement or hypertrophy of atria or ventricles; Myocardial ischemia, injury, infarction; Pericarditis; Effects of some drugs ( Digitalis, Quinidine, Amiodarone, etc. ); Disturbance of electrolyte metabolism ( hypokalemia, hyperkalemia, hypocalcemia, hypercalcemia, etc. )

4. Dipole Theory

5. Electrode Records Upward or Downward Deflection

6. ECG Leads Standard limb leads: Ⅰ, Ⅱ, Ⅲ ( Augmented ) Unipolar limb leads: aVR, aVL, aVF Chest ( precordial ) leads: V1~V6.

11. Precordial Leads

13. Sequence of Ventriclular Depolarization

14. Projection of a QRS Vector-loop onto Frontal and Horizontal Planes

15. Projection of a QRS Vector-loop onto Limb and Predordial Leads

16. Configuration of a QRS in Limb Leads

17. Configuration of a QRS in Precordial Leads

18. Measurements of an EKG

20. Mean QRS Vector

21. Mean QRS Axis The major direction of the depolariation forces in the ventricle expressed as degrees on the hexaxial system. Normal QRS axis: -30 ° ~ +90 ° Left axis deviation( LAD ): -30 ° ~ -90 ° Right axis deviation( RAD ): +90 ~ +180 ° Extreme RAD or Indeterminate axis: +180 ° ~ -90 °

22. QRS Axis Deviation

23. Normal QRS Axis

24. Left Axis Deviation

25. Right Axis Deviation

26. Determination of a QRS Axis by Calculation

27. Causes of LAD or RAD Causes of LAD: Normal variant; LVH; Older age; COPD; LAFB ( left anterior fascicular block); inferior MI; Preexcition syndrome Causes of RAD: Normal variant; RVH; Younger age; COPD; LPFB; Lateral MI; Preexcition syndrome

28. Sequence of Heart Activation

29. Measurements of an EKG

30. ECG Nomenclature P wave : depolarization of right and left atria QRS complex : depolarization of right and left ventricles ( 0.06’’~0.10’’) ST segment : beginning of repolarization of both ventricles T wave : repolarization of both ventricles U wave : late repolarization

31. ECG Nomenclature (Cont.) P-R interval : represents the time for an impulse to travel from SAN through specialized atrial conduction pathway… to Purkinjie cells. Includes depolarization of both atria and passage of the impulse to the point of ventricular muscle stimulation ( 0.12’’~0.20’’) QT interval : the depolarization and repolarization of two ventricles ( 0.32’’~0.44’’)

32. Normal P wave Deflection : ↑ in Ⅱ, aVF, V3~V6; ↓ in aVR; ↑or ↓in V1~V2(varient) (Sinus P: + PR ≥ 0.12’’ ) Amplitude : < 0.25mV in limb leads; < 0.2mV in precordial leads Duration : < 0.11’’

34. Normal QRS Complex R aVL < 1.2; R aVF < 2.0 qR, Rs or rS aVL, aVF < 0.5 QS, rS, rSr’ or Qr aVR 1.2~1.8, < 2.5 qR, qRs, Rs or R V5, V6 - RS (R/S1) V3, V4 < 1.0 rS V1, V2 Amplitude of R (mV) Deflection Leads

35. Progression of R in Precordial Leads

36. Low Voltage | R | + | S | or | Q | + | R | < 0.5mV in every limb leads or < 0.8 mV in every precordial leads Clinical significance: pericardial effusion, pulmonary emphysema, obesity, etc.

37. Abnormal (Pathological) Q Amplitude: > 1/4R Duration: > 0.04’’ Clinical significance: myocadial infarction (MI), LBBB

38. T Wave Deflection: same as the main deflection of QRS in the same lead ( ( ↑ ) in Ⅰ , Ⅱ, and V4~V6; ( ↓ ) in aVR; ( ↑ ) or (+/-) or ( ↓ ) in Ⅲ, aVL, aVF, V1~V3 Amplitude: > 1/10 R, 1.2~1.5mV in precordial leads( T V1 < 0.4mV)

39. S-T Segment ↑ : < 0.3mV in V1~V3, < 0.1mV in V4~V5 and limb leads ↓ : < 0.05mV in any leads

40. Interpretation of an Electrocardiography 1) Rhythm and rate: P-R interval; P abnormalities; abnormalities of rhythm 2) QRS: Mean electrical axis; abnormalities of configuration 3) S-T and T QRS-T angle; abnormalities( elevation or depression of ST, flat or inverted or sharp-peaked T ) 4) Q-T Interval: Impression and Comment

41. A Normal EKG

42. Enlargement of Left Atrial

44. Left Atrial Enlargement Broad notched P Duration: > 0.11’’, distance between peaks > 0.04’’ P mitrale . PtfV1: < -0.04mms

45. Right Atrial Enlargement

47. Right Atrial Enlargement Tall, peaked P. Amp.: > 0.25mV in Ⅱ, aVL or aVF. P pulmonale

48. Left Ventricular Hypertrophy

50. Left Ventricular Hypertrophy 1) Increased mV of QRS: R V5 > 2.5, R V5 +S V1 ≥ 3.5 (F), 4.0 (M); R Ⅰ > 1.5, R aVL > 1.2, R Ⅰ +S Ⅲ > 2.5 or R aVF > 2.0, R Ⅱ +R Ⅲ > 4.0 2) LAD: usually < -30 ° 3) Delayed onset of intrinsicoid deflection: VAT ( R peak time ) V5 > 0.05’’ 4) Repolarization changes: depressed ST and inverted T in V5, V6, ( Ⅰ, aVL)

51. Right Ventricular Hypertrophy

52. Right Ventricular Hypertrophy 1) Increased mV of QRS: R V 1 > 1.0, R V1 +S V5 >1.05( 1.2), R V1 /S V1 > 1 S Ⅰ / R Ⅰ > 1, R aVR ↑ 2) RAD: usually -90 ° ~ -110 ° 3) Delayed onset of intrinsicoid deflection: VAT( R peak time ) V1 > 0.05’’ 4) Repolarization changes: depressed ST and inverted T in V1, V2

54. AMI-99

58. Sinus Arrythmia Sinus P; PRx-PRn ≥ 0.12’’ Clinical Significance: None

59. Sinus Arrythmia

60. Sinus Tachycarcardia and Bradycardia Sinus Tachycarcardia: 1) Sinus P 2) Frequency of P > 100/min. Clinical Significance: Fever, anemia, hyperthyrodism, myocarditis, heart failure, etc. Sinus Bradycardia (Sinus P < 60 / min ): Clinical Significance: Sports men, Inferior AMI, hypothyrodism, obstructive jaundice, ICP ↑, etc.

62. Atrial Premature Contraction (APC) Premature P’: differs from Sinus P ( bizarre or inverted). PR ≥ 0.12’’ QRS’ similar to sinus beat Compensatory pause: Incomplete Nonconducted or block APC Clinical significance:

65. Ventricular Premature Contraction

66. Ventricular Premature Contraction (VPC) Premature an abnormal QRS without a preceded P : wide and bizarre; Duration of QRS ≥ 0.12’’; Deflection of T: opposite to main deflection of QRS; Compensatory pause: complete Interpolated VPC; Multiform VPCs; Bigeminy; trigeminy; couplet; triplet (V. techycardia) Clinical significance:

68. PVC

69. Junctional Premature Contraction

70. Junctional Premature Contraction (JPC) Premature QRS with or without a Retrograde P (P’) (preceding or following QRS); P’-QRS < 0.12’’ or QRS-P’ < 0.20’’; Compensatory pause: Completed or incompleted. Clinical Significance:

71. Paroxymal Supraventricular Tachycardial ( PVST )

72. Supraventricular Paroxysmal Tachycardia Frequency of QRS > 140 (160)/min; Rhythm: regularly; Duration of QRS: ≤ 0.10’’. Clinical significance:

73. Ventricular Paroxysmal Tachycardia

74. Ventricular Paroxysmal Tachycardia

75. Ventricular Paroxysmal Tachycardia ≥ 3 rapid and continuous PVC; Frequency: 140~200/min ( faster than P); Shape of QRS: wide, bizarre, t ≥ 0.12’’; Deflection of T: Ventricular capture or Fusion. Clinical significance:

76. Atrial Flutter

78. Atrial Flutter Disappearance of P, substituted by F waves; Frequency of F: 250~350/min ( saw-tooth ); Ratio of atrial to ventricular conduction: 2:1, 3:1, 4:1, etc. Clinical significance:

79. Atrial Fibrillation Disappearance of P, substituted by irregular undulations of the baseline ( f waves ); Frequency of f: 350~600/min; Irregularly irregular R-R intervals. Clinical significance

80. Ventricular Flutter

81. Ventricular Flutter Undulating regular QRS waves; Frequency: 180~250/min; ST or T: Not identified. Clinical Significance : Precursor of ventricular fibrillation.

82. Ventricular Fibrillation Bizarre, irregularly irregular fibrillatory waves; Frequency: 250~500/min; P, QRS, T: not identified Clinical significance:

85. Ⅰ 0 Auriculo-Ventricular Block ( Ⅰ 0 AVB ) P-R > 0.20”; There is a QRS followed each P. Clinical significance:

86. 2nd Degree AV Block, Type I

87. Ⅱ 0 Degree AV Block ( 1. Mobitz Type Ⅰ ) ( Wenckebach) Group beating; Progressive lengthening of P-R until a P is completely block ->An absent QRS; Repeated cycle. Clinical significance:

88. Mobitz II 2nd degree AV block

89. Ⅱ Degree AV Block ( 2. Mobitz Type Ⅱ ) Constant P-R; Absent of a QRS periodically. High degree or advanced AV block: A / V ≥ 3:1 Clinical significance:

90. Ⅲ Degree AV Block

91. Ⅲ Degree AV Block ( Complete AV Block ) The atria ( P waves ) beat independently of the ventricles ( QRS ) Atrial rate is faster than ventricular rate ( escape rhythm ) Clinical significance: Drugs ( digoxin… ), degeneration from aging, AMI, etc.

93. Right Bundle Branch Block

94. Right Bundle Branch Block (RBBB ) QRS duration ( ≥ 0.12’’- complete; 0.10~ 0.11- incomplete ); RSR’ ( R’ > R ) in the “right ventricular leads” - V1, V2; Wide or slurred S in the “left ventricular leads” - V5, V6 ( Ⅰ , aVL); Ventricular repolarization changes ( downsloping ST and inverted T- opposite direction to R’) in V1, V2 Late onset of intrinsicoid defletion ( R peak time ) in V1, V2 ( ≥ 0.04’’ )

95. RBBB

96. Left Bundle Branch Block

97. Left Bundle Branch Block (LBBB ) QRS duration ( ≥ 0.12’’- complete; 0.10~ 0.11 - incomplete ); Wide and notched R in the left ventricular leads”- V5, V6 ( Ⅰ , aVL); Wide or slurred S in the “Right ventricular leads”- V1, V2; Ventricular repolarization changes ( downsloping ST and inverted T- opposite direction to R) in V5, V6 Late onset of intrinsicoid defletion ( R peak time ) in V5, V6 ( ≥ 0.06’’ )

98. LBBB

99. Coronary Artery

100. Angina Pectoris

101. Classic Angina Pectoris ( Transient subendocardial ischemia ) Depression of ST; ( flat or inverted T )

102. Classic Myocardial Infarction

103. Evolutionary Changes of EKG in AMI

104. Stages of MI Hyperacute; Acute; Subacute; Old.

105. Location of MI

106. Hyperacute Inferior MI

107. Acute Inferior MI

108. Acute Extensive Anterior/ Anterolateral MI

109. Subacute Inferior MI ( Inferior and Anteroseptal )

110. Old Inferior MI, PVCs, and Af

111. Mechanism of WPW

113. Preexcitation Syndrome (WPW) ( Type A )

114. Preexcitation Syndrome (WPW) ( Type B )

115. Thank You !

118. Angina Variant ( Prinzmetal angina , Transient subepicardial ischemia ) Slope-elevation of ST; Tall and widened T; Increased VAT. Clinical significance:

119. Precordial Leads

120. Sequence of Heart Activation