1. EKG

2. Reading: Klabunde, Cardiovascular Physiology Concepts
Chapter 2 (Electrical Activity of the Heart) pages 27-37
Dubin, Rapid Interpretation of EKG’s, 6th Edition.

3. Check these hyperlinks out!
Dubin’s EKG Pocket Guide

4. Basic Principles

5. Basic Principles
The EKG records the electrical activity of contraction of the heart muscle
Depolarization may be considered an advancing wave of positive charges within the heart’s myocytes

7. – + – + + – - - - - - - - - - - - + + + + + + + +

8. – + – + + – - - - - - - - - - - - - - - - - - - - - - - +
Depolarization Wave –

9. Depolarization
Repolarization

10. Conduction System

11. AN Region N Region NH Region
SA Node
Right Atrial Tracts
Anterior
Internodal
Pathway
Middle
Internodal
Pathway
Posterior
Internodal
Pathway
Anterior interatrial
myocardial band
(Bachmann’s Bundle)
Left Atrium
AN Region N Region NH Region
AV Node
Bundle of His
Right Bundle Branch
Left Bundle Branch
Anterior Division
Posterior Division

12. Sinus Rhythm The SA (Sinus) Node is the heart’s dominant pacemaker.
The ability of a focal area of the heart to generate pacemaking stimuli is known as Automaticity.
The depolarization wave flows from the SA Node in all directions.

13. Atrio-Ventricular (AV) Valves
Prevent blood backflow to the atria
Electrically insulate the ventricles from the atria

14. AV Conduction
AV node is situated on right side of interatrial septum near the ostium of the coronary sinus
When the wave of depolarization enters the AV Node, depolarization slows, producing a brief pause, thus allowing time for the blood in the atria to enter the ventricles.

20. Rapid Repolarization Phase
ST Segment
Rapid Repolarization Phase
Plateau

23. QT Interval
Ventricular Systole

24. Recording the EKG

25. Limb Leads I II
III
AVR
AVL
AVF
Chest Leads V1 V2 V3 V4 V5 V6

33. Autonomic Nervous System

38. Check for these on every EKG
RATE
Rhythm
Axis
Hypertrophy
Infarction

39. Sinus Rhythm The SA (Sinus) Node is the heart’s dominant pacemaker.
The generation of pacemaking stimuli is automaticity.
The depolarization wave flows from the SA Node in all directions.

40. Sinus Rhythm The Sinus Node is the heart’s normal pacemaker
Normal Sinus Rhythm: /min.
Sinus Bradycardia: Less than 60/min.
Sinus Tachycardia: More than 100/min.

41. Automaticity Foci Level Inherent Rate Range Atria AV Junction
Ventricles
Inherent Rate Range
60-80/min.
40-60/min.
20-40/min.

42. Overdrive Suppression

50. RATE
Say “300, 150, 100” …“75, 60, 50”
But for bradycardia: rate = cycles/6 sec. strip ✕ 10

51. Check for these on every EKG
Rate
RHYTHM
Axis
Hypertrophy
Infarction

52. RHYTHM
Identify the basic rhythm, then scan tracing for prematurity, pauses, irregularity, and abnormal waves.
Check for: P before each QRS.
Check for: QRS after each P.
Check: PR intervals (for AV Blocks).
Check: QRS interval (for Bundle Branch Block)

53. Sinus Rhythm Origin is the SA Node (“Sinus Node”)
Normal sinus rate is 60 to 100/minute
Rate more than 100/min. = Sinus Tachycardia
Rate less than 60/min. = Sinus Bradycardia

55. Sinus Bradycardia

56. Sinus Tachycardia

57. Arrhythmias
Irregular rhythms
Escape
Premature beats
Tachy-arrhythmias

58. Irregular Rhythms Sinus Arrhythmia Wandering Pacemaker
Multifocal Atrial Tachycardia
Atrial Fibrillation

59. Sinus Arrhythmia Irregular rhythm that varies with respiration.
All P waves are identical.
Considered normal.

60. Wandering Pacemaker Irregular rhythm.
P waves change shape as pacemaker location varies.
Rate under 100/minute

62. Multifocal Atrial Tachycardia
Irregular rhythm.
P waves change shape as pacemaker location varies.
Rate greater than 100/minute

64. Atrial Fibrillation Irregular ventricular rhythm.
Erratic atrial spikes (no P waves) from multiple atrial automaticity foci.
Atrial discharges may be difficult to see.

66. Escape Escape Rhythm Escape Beat Atrial Escape Rhythm
Junctional Escape Rhythm
Ventricular Escape Rhythm
Escape Beat
Atrial Escape Beat
Junctional Escape Beat
Ventricular Escape Beat

71. Premature Beats Premature Atrial Beat Premature Junctional Beat
Premature Ventricular Contraction (PVC)

75. Atrial Bigeminy

79. PVC’s

81. Bigeminy

84. Tachyarrhythmias

85. Paroxysmal Atrial Tachycardia (Supraventricular Tachycardia)
An irritable atrial focus discharging at /min. produces a normal wave sequence, if P’ waves are visible.

86. P.A.T. with block (Supraventricular Tachycardia)
Same as P.A.T. but only every second (or more) P’ wave produces a QRS.

87. Paroxysmal Junctional Tachycardia
AV Junctional focus produces a rapid sequence of QRS-T cycles at /min.
QRS may be slightly widened.

88. Paroxysmal Ventricular Tachycardia
Ventricular focus produces a rapid ( /min) sequence of (PVC-like) wide ventricular complexes.

90. Atrial Flutter
A continuous (“saw tooth”) rapid sequence of atrial complexes from a single rapid-firing atrial focus.
Many flutter waves needed to produce a ventricular response.

92. Ventricular Flutter
A rapid series of smooth sine waves from a single rapid-firing ventricular focus
Usually in a short burst leading to Ventricular Fibrillation.

95. Atrial Fibrillation
Multiple atrial foci rapidly discharging produce a jagged baseline of tiny spikes.
Ventricular (QRS) response is irregular.

96. Ventricular Fibrillation
Multiple ventricular foci rapidly discharging produce a totally erratic ventricular rhythm without identifiable waves.
Needs immediate treatment.

97. Block
Sinus Block
AV Block
Bundle Branch Block
Hemiblock

98. Sinus (SA) Block
An unhealthy Sinus (SA) Node misses one or more cycles (sinus pause)
The Sinus Node usually resumes pacing
However, the pause may evoke an “escape” response from an automaticity focus

100. 1° AV Block
PR interval is prolonged to greater than 0.2 sec (one large square)

101. 1° AV Block

103. 2° AV Block (Some P waves without QRS Response)
Wenkebach
PR gradually lengthens with each cycle until the last P wave in the series does not produce a QRS

104. 2° AV Block (Some P waves without QRS Response)
Mobitz
Some P waves don’t produce a QRS response.
Intermittent may cause an occasional QRS to be dropped.
More advanced may produce a 3:1 pattern or higher AV ration.

105. 2° AV Block (Some P waves without QRS Response)
May be Mobitz or Wenkebach.

107. 2° AV Block

109. 3° AV Block (“Complete” Block)
P waves of SA node origin
QRS’s if narrow, and if the ventricular rate is 40-60/min., then origin is a junctional focus.

110. 3° AV Block (“Complete” Block)
P waves of SA node origin
QRS’s if PVC-like, and if the ventricular rate is 20-40/min., then origin is a ventricular focus.

111. 3° AV Block

112. Bundle Branch Block Find R, R' in right or left chest leads
Always check: Is QRS within 3 tiny squares?

114. Left Bundle Branch Block

116. Right Bundle Branch Block

117. Hemiblock
Block of Anterior or Posterior Fasicle of the Left Bundle Branch
Always check: Has Axis shifted outside normal range?
Anterior Hemiblock:
Axis shifts leftward > L.A.D. Look for Q1S3
Posterior Hemiblock:
Axis shifts rightward > R.A.D. Look for S1Q3

118. Left Anterior Hemiblock

119. Check for these on every EKG
Rate
Rhythm
AXIS
Hypertrophy
Infarction

120. Using Vectors to Represent Electrical Potentials
A vector is an arrow that points in the direction of the electrical potential generated by current flow
The arrowhead of the vector is in the positive direction
The length of the arrow is drawn proportional to the voltage of the potential

121. N W E S

123. + + + – + – + – + + – + – + + – – + + + + – – + + – + + – + – + + + – + – + + – – + + + + + + + + +

124. LV RV

130. + + + – + – + – + + – + – + + – – + + + + – – + + – + + – + – + + + – + – + + – – + + + + + + + + +

131. Lead I – +

133. Axis
QRS above or below baseline for Axis Quadrant (Normal vs. R or L Axis Dev.)
For Axis in degrees, find isoelectric QRS in a limb lead
Axis rotation in the horizontal plane (chest leads) find “transitional” (isoelectric) QRS

138. Causes of Axis Deviation
Change of the position of the heart in the chest
Hypertrophy of one ventricle
Myocardial infarction
Bundle branch block

139. Check for these on every EKG
Rate
Rhythm
Axis
HYPERTROPHY
Infarction

140. Hypertrophy P wave for Atrial hypertrophy
R wave for Right Ventricular Hypertrophy
S wave depth in V1 + R wave height in V5 for Left Ventricular Hypertrophy

141. Right Atrial Hypertrophy
Large, diphasic P wave with tall initial component
Seen in lead V1

142. Left Atrial Hypertrophy
Large, diphasic P wave with wide terminal component
Seen in lead V1

143. Right Ventricular Hypertrophy
R > S wave in V1
R wave gets progressively smaller from V1-V6
S wave persists in V5-V6
RAD with slightly widened QRS
Rightward rotation in the horizontal plane

145. Left Ventricular Hypertrophy
mm of S in V1 +
mm of R in V5
Total:
If more than 35 mm there is LVH

146. Left Ventricular Hypertrophy
LAD with slightly widened QRS
Leftward rotation in the horizontal plane
Inverted T wave
Slants downward gradually, but up rapidly

147. Hypertrophy Left Ventricle and Left Atrium

148. Check for these on every EKG
Rate
Rhythm
Axis
Hypertrophy
INFARCTION (and Ischemia)

149. Infarction Scan all leads for: Q waves Inverted T waves
ST segment elevation or depression
Find the location of the pathology and then identify the occluded coronary artery

150. Necrosis = Q wave (significant Q’s only)
Significant Q wave:
One mm wide (0.04 sec in duration) or
1/3 the amplitude (or more) of the QRS
Omit lead AVR when looking for significant Q’s
Old infarcts: Q waves remain for a lifetime

151. Injury = ST elevation Signifies an acute process
ST elevation associated with significant Q waves indicates an acute (or recent) infarct
ST depression (persistent) may represent a “subendocardial infarction”

153. Ischemia = T wave inversion
Inverted T wave (of ischemia) is symmetrical
Normally T wave is upright when QRS is upright, and vice versa
Usually in the same leads that demonstrate signs of acute infarction (Q waves and ST elevation)

160. Inferior Infarction

161. Inferior Infarction (+ LBBB)

164. Anterior Infarction

166. Postero-Lateral Infarction

167. Miscellaneous

168. Digitalis EKG appearance with digitalis Salvador Dali mustache
T waves depressed or inverted
QT interval shortened

169. Digitalis Digitalis Excess (Blocks) Digitalis Toxicity
SA Block
P.A.T. with Block
AV Blocks
AV Dissociation
Digitalis Toxicity
(Irritable foci firing rapidly)
Atrial Fibrillation
Junctional or Ventricular Tachycardia
Multiple PVS’s
Ventricular Fibrillation

170. Calcium

171. Decreased Potassium (Hypokalemia)

172. Hyperkalemia

173. Pulmonary Embolism S1Q3T3 Acute Right Bundle Branch Block
Wide S in I, large Q and inverted T in III
Acute Right Bundle Branch Block
R.A.D. and clockwise rotation
Inverted T waves in V1 – V4
ST depression in II

174. Pulmonary Embolism

175. Pacemakers

176. Wolf-Parkinson-White Syndrome

177. Wolf-Parkinson-White Syndrome

178. Review the 12-lead EKG on top in the next slide (EKG b).
Anything unusual about it?

181. The End