12 Lead ECG. Presented by Rebecca Sevigny BSN, RN Professional Practice & Development Dept.

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1 12 Lead ECG Presented by Rebecca Sevigny BSN, RN Professional Practice & Development Dept.

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3 Two Main Coronary Arteries RCA LCA which branches into Left Anterior Descending Circumflex Artery Two Main Coronary Arteries

4 Right Coronary Artery Myocardium Supplied: Right atrium/right ventricle Inferior wall of LV Posterior 1/3 of intraventricular septum Conduction Structures Supplied: SA Node (> 50%) AV Node (~80%) Posterior division of left bundle (part)

5 Circumflex Artery Myocardium Supplied: Left Lateral wall of the left ventricle, back side of heart Conduction Structures Supplied: SA Node (~40%)

6 Cardiac Conduction System

7 Conduction: Normal P-QRS-T

8 Normal P-QRS-T P Wave PR Interval QRS Complex ST Segment Represents Atrial depolarization Atrial depolarization and delay at the AV Node (AV conduction time) Ventricular depolarization Interval between ventricular depolarization and repolarization Duration < 0.12 seconds seconds seconds Measure from end of QRS (J-point) to Height < 2.5 mm Measure start of P wave to start of QRS Shape Smooth Prolonged indicates a conduction block Orientation Positive in Leads I,II,aVF, V4 Negative in avr Shortened indicates accelerated conduction or junctional in origin Q- First negative deflection R- First positive deflection S- Negative deflection after R wave beginning of T wave In relation to isoelectric line: Depression/Negative indicates ischemia Elevation/Positive indicates injury

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10 = Electrical current flowing toward a positive electrode produces an upward deflection of the QRS

11 Electrical current flowing away from a positive electrode produces a downward deflection of the QRS

12 Electrical current flowing perpendicular to a positive electrode produces a biphasic QRS

13 ECG Paper Speed Amplitude

14 Systematic Approach to Interpretation General Impression/Anything that sticks out? Rate, intervals & rhythm Axis P waves & QRS complexes Ischemia or infarction Any other unusual findings Putting it all together for the patient

15 Is a diagrammatic way to show strength and direction of electrical impulse Indicates the direction of the depolarization in time They add up when flowing in the same direction If at an angle they add or subtract energy Vector

16 Vectors & Axis

17 Activation of the Ventricle Vector #1 Septum depolarizes Left to Right Successive Vectors Progressive depolarization of the ventricles Begins in endocardium and spreads to epicardium What ventricle produces more force??

18 Is the mean direction of the cardiac impulse during ventricular depolarization Normal axis is -30 degree to +90 degree. Clinical use of Axis

19 Axis Deviation

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24 The Normal 12 Lead Ten actual leads are placed on the patient: 3 limb leads (Leads I,II,III; AVR,AVL,AVF) 1 ground lead (right leg lead) 6 chest or precordial leads (V 1 V 2, V 3, V 4, V 5, V 6 )

25 Review of Lead Placement & Waveform Production

26 The 12 Lead EKG 12 angles or pictures of the electrical activity of the heart 6 Limb Leads 6 Chest or Pre-cordial Leads I II III AVR AVL AVF V1 V2 V3 V4 V5 V6

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28 Bipolar and Unipolar Leads Bipolar: LEAD 1 LEAD 2 LEAD 3 -Rt arm & +Lt arm -Rt arm & + Lt leg -Rt arm & + Lt leg Unipolar AVR Rt arm AVL Lt arm AVF Lt leg Chest Leads / V Leads

29 Lead I Energy flows toward the positive electrode of lead I, resulting in an upward deflection of the QRS. Bipolar Limb Lead Camera(+) is on Left shoulder looking toward the Right Shoulder Looks at high lateral wall of LV What coronary artery supplies this area of the heart? Positive/upright P QRS T

30 Lead II Mean vector flows directly at the positive lead II electrode, this lead usually has the most upright QRS complexes and the most prominent P waves of the entire 12-lead ECG. Bipolar Limb Lead Camera(+) is on Left leg looking toward the Right Shoulder Looks at inferior wall of LV What coronary artery supplies this area of the heart? Positive/upright P QRS T

31 Lead III Mean vector flow approaches lead III downward from the right, again producing an upward QRS deflection. Bipolar Limb Lead Camera(+) is on Left leg looking toward the Left Shoulder Views inferior wall of LV Supplied by right coronary artery-rca Positive but usually less positive and can be biphasic Why is the QRS biphasic?

32 Its positive monitoring electrode is located on the right arm and looks downward and to the left. Augmented Voltage Right Arm Camera(+) is on Right Shoulder looking somewhere between the Left Shoulder and Left leg Mean vector moves away from avr. What will the complexes look like? Not typically a diagnostic lead

33 Positive electrode on the left arm and looks to the right and downward toward to the center of the heart Augmented Voltage Left Arm Looks at lateral wall of LV Supplied by circumflex artery - CX All complexes should be positive

34 Positive monitoring lead on the left leg and looks straight up to the center of the chest. Augmented Voltage (left) Foot Looks at inferior wall of LV Supplied by right coronary artery RCA All complexes should be positive

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37 R Wave Progression Should see a progression or increase in R wave amplitude from negative to positive in leads V 1 to V 4 - V 1 - R wave is generally smallest or most negative - V 4 - R wave is typically the tallest or most positive Lack of R wave progression may be related to : Disease state, CAD, Septal wall MI, breast tissue, poor lead placement, rotated heart, obesity, COPD

38 Normal EKG

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40 Dextrocardia

41 Systematic Approach to Interpretation General Impression/Anything that sticks out? Rate, intervals & rhythm Axis P waves & QRS complexes Ischemia or infarction Any other unusual findings Putting it all together for the patient

42 Smooth Less than 0.12 wide Less than 2.5 tall Positive in what leads Atrial Enlargement

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45 What about that QRS Big ventricles = big vectors = big QRS s Infarcted areas are electrically inert, therefore: see smaller complexes or see unopposed vectors from area opposite the infarct site Pericardial effusion, excess body fat: see smaller complexes

46 QRS Amplitude & Width Limb leads: < 5mm is abnormal Precordial: < 10mm is abnormal QRS width > 0.10 secs is abnormal Causes - ventricular paced, BBB

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48 Examples of QRS Complexes

49 Left Ventricular Hypertrophy

50 Ventricular Hypertrophy Depth of S wave in V1 or V2 (whichever is deeper) to R wave in V5 or V6 (tallest) > 35 mm The R wave in lead avf is > 20 mm LVH Any precordial lead > 45 mm The R wave in lead I is > 12mm The R wave in avl is > 11mm

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52 RVH

53 Ventricular Hypertrophy R:S ratio is > 10 mm in V1 R V R:S ratio is > 10 mm in V2 H

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55 Normal <.04 Less than a small box Seen in Leads I, III, AvL, V5 & V6 Septal Q waves in Lead I and avl Physiological Q Wave

56 Pathological Q Wave Height is 1/3 the size of entire QRS complex Width is one square or greater than 0.04 seconds in duration Damage from old infarcts cause Q waves that last a lifetime.

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66 This Photo by Unknown Author is licensed under CC BY-NC QRS

67 WPW

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69 PR interval <.12 Delta wave QRS >.110 ms

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73 Wide Complex Tachycardia vs. V-tach Complexes > 160 ms Absence of RBBB or LBBB morphology Extreme axis deviation: Negative in I + avf AV dissociation Capture beats Fusion beats Positive or negative concordance in precordial leads with no RS seen Brugada s sign- Onset of QRS to nadir of S wave >100ms Josephson s sign Notching near the nadir of the S-wave RSR complexes with a taller left rabbit ear.

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82 Systematic Approach to Interpretation General Impression/Anything that sticks out? Rate, intervals & rhythm Axis P waves & QRS complexes Ischemia or infarction Any other unusual findings Putting it all together for the patient

83 ST Segment ST Segment: Measured from the J point to the T wave ST should be isoelectric ST depression & T wave in opposite direction from what is normal, usually indicates myocardial ischemia

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85 ST Depression = Ischemia St depression 0.5mm in 2 or more contiguous leads Inverted, symmetrical T waves T wave deflection is opposite from QRS T wave inversion is usually in same leads that demonstrates signs of acute infarction

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87 ST Segment cont d ST Depression can also be related to: Digoxin Toxicity Pulmonary Embolism Ventricular Hypertrophy Left Bundle Branch Block ST elevation with/without T wave changes believe it to be associated with myocardial injury

88 ST Elevation = Current Injury Depicts current myocardial injury If elevated >1mm in two or more contiguous leads suspect acute injury > 2mm of ST elevation in precordial leads Can see reciprocal ST depression in other leads ST elevation with/ without T wave changes believe it to be associated with myocardial injury

89 Sgarbosa s Criteria Concordant ST elevation > 1mm in leads with a positive QRS complex (score 5) Concordant ST depression > 1 mm in V1- V3 (score 3) Sgarbossa s Criteria Excessively discordant ST elevation > 5 mm in leads with a negative QRS complex (score 2). A total score of 3 is reported to have a specificity of 90% for diagnosing myocardial infarction.

90 ST segments with LBBB

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93 Left Ventricle Lead Orientation Wall of LV Leads Artery Inferior II, III,AVF RCA Anterior (extensive) V 1-6, I, AVL LM Anterior-Septal V 1-4 LAD Lateral V 5-6, I, AVL Cx Posterior V 1 & V 2 (mirror image) RCA

94 Causes for ST elevation Pericarditis Coronary Vasospasm LBBB LVH Paced rhythms Ventricular aneurysm Elevated ICP Drug induced Myocardial Infarction

95 AMI Location Correlation I Lateral avr V 1 Septal V 4 Anterior II Inferior avl Lateral V 2 Septal V 5 Lateral III Inferior avf Inferior V 3 Anterior V 6 Lateral

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97 Acute Anterior MI

98 Extensive Anterior/Lateral MI

99 Acute Inferoposterior MI with RV Infarct

100 Systematic Approach to Interpretation General Impression/Anything that sticks out? Rate, intervals & rhythm Axis P waves & QRS complexes Ischemia or infarction Any other unusual findings Putting it all together for the patient

101 And those T waves.. Think shape, polarity and amplitude Shape: asymmetry is the norm! Polarity: can be positive, negative or in between. Amplitude: > 5 in Limb leads is abnormal > 10 mm in precordial leads is abnormal

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103 T Waves Shape Polarity Size

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105 Shortened down sloping ST segment Long PR interval T wave inversion

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109 Electrolytes and the EKG

110 HYPERKALEMIA Peaked T waves Wide bizarre QRS Bradyarrhythmias AV blocks Junctional rhythms

111 HYPOKALEMIA Mild ST depression Decreased T wave amplitude Minimal prolong in QRS U wave

112 HYPOCALCEMIA Prolonged QTc ST segment depression At risk for torsades

113 HYPERCALCEMIA Short QT interval Decrease in ST segment duration Prolonged PR interval Flattened or inverted t waves for some people

114 HYPOMAGNESEMIA Prolonged QT Widening of QRS Peaked T waves

115 HYPERMAGNESEMIA Prolonged PR interval Prolonged QRS duration Prolonged QT interval

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119 LVH with Strain RVH with Strain

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122 Dubin, D. (2000) Rapid Interpretation of EKG s Cover Publishing Company Fort Meyers Florida Garcia, B. (2013). 12-Lead EKG The Art of Interpretation. Jones & Bartlett Burlington, MA. Phalaen, T. (1996) The 12-Lead ECG in Acute Myocardial Infarction Mosby LifelineLearning. Phalen, T., Aehlert, B. (2006) The 12-Lead ECG in Acute Coronary Syndromes Elsevier Mosb St. Louis, Mo Thaler, M. (2012) The Only EKG Book You ll Ever Need Lipincott & Williams & Wilkins Philadelphia, PA Reeder, G.s., Kennedy, H.L Criteria for the diagnosis of Acute Myocardial Infrarction UpToDate References