                       EKG READING PEARLS

READING SCHEME:
     1.  Rate
     2.  Rhythm
     3.  Axis
     4.  Hypertrophy & Blocks
     5.  Ischemia, Injury, Myocardial Infarction
     6.  Miscellaneous Effects

RATE:
1.  Number Cycles in 6 secs x 10 = rate

2. Bold Dark Line:
     300   150    100    75    50
          NOTE: If rate < 50 use 6 sec method

RHYTHM
     Sinus in Origin
     Superventricular dysrhythmia
     Junctional Beats & Rhythms
     Ventricular Dysrhythmia
     A-V Irregularities & Blocks

AXIS:
     Look at 1st 0.4 sec of QRS complex in Leads I and AVF
     AXIS DEVIATION Lead 1    Lead AVF       VALUES                 Normal (None)         + (up)                 +      0  - + 90
             RAD              -(down)               +                 +90  - +180
         Extreme RAD                  -                      -                -90 - -180
              LAD                 +                      -                    0 - -90






HYPERTROPHY & BLOCKS
Atrial Hypertrophy:
1. Right Atrial Hypertrophy (p-pulmonale)
     Tall narrow P waves (< 2.5mm) in Leads II (most sensitive), III, AVF
     Width of P wave not increased
      2 mm upright (first part) of P wave in V1 or V2

2.  Left Atrial Hypertrophy (p-mitrale)
     P waves are wide (> 3mm (0.12sec) and notched in 1 or more limb leads
     P waves of V1 and V2 may have negative terminal component with depth &
          width  1mm

3. Biatrial Hypertrophy
     Criteria for both RAH and LAH is met

Ventricular Hypertrophy
1. Right Ventricular Hypertrophy (RVH)
     RAD
     R wave > S wave in V1 (R:S > 1)
     R wave in V1 + S wave in V6  11mm
     Deep S waves in V5 & V 6, I, AVL
     RR' may be present in V1
     2o T wave changes in V1 - 3 = RV Strain Pattern
          S-T depression with upward convexity in leads with + QRS
          Asymmetric T-wave inversion

2. Left Ventricular Hypertrophy
     1.   R or S in V1  15 mm 
          S in V1 - 3  25 mm                
          R in V4 - 6  25 mm
          R in I + S in III  15 mm
          R in V5 or V6 + S in V1  35mm 
          R in II, III or AVF 20 mm
          R in AVL  13 mm
               QRS interval 0.09 sec or more           

3. Biventricular Hypertrophy
     LVH per chest leads (voltage criteria) + RAD per limb leads
     LVH per chest leads + prominent R waves in Right Chest Leads
     Shallow S wave in V1 + strikingly deeper S in V2
     RVH per chest Leads + LAD per limb leads

Fascicular Blocks:
1. Left Bundle Branch Block (LBBB)
     QRS > 0.12 sec
     Broad QS or rS in V1 - 3
     RR' in I, AVL, V4 - 6
     NOTE: CAN'T Diagnose Q wave or Voltage MI if LBBB present
2. Right Bundle Branch Block (RBBB)
     QRS > 0.12 sec
     Deep and slurred S in I, AVL, V4 - 6
     rR' in V1 - 3
     NOTE: Remember to look for Hemiblocks if RBBB present
3. Left Anterior Hemiblock
     LAD, Axis = -45 to -90
     Normal QRS duration unless RBBB also present
     Small q I and small r in III
     No other factors for LVH
4. Left Posterior Hemiblock
     RAD; Axis +105 - +180
     Normal QRS duration unless RBBB also present
     Small r in I and small q in III

Ischemia, Injury, MI
Ischemia:
     Symmetric T wave inversion
     ST segment depression
     U wave inversion
     Tall peaked "hyperacute" T waves
Injury:
     ST segment elevation > 1mm above baseline
     T wave inversion
Myocardial Infarction:
     Significant Q waves (>1mm wide or > 25% of R wave height)
     Reciprocal Changes - occur in leads opposite from area of infarction
          Less magnitude than changes that occur in leads of 1o involvement


Localization of MI 
     Anteroseptal        Q or QS in V1 - 3
     Anterior            Q or QS in V2 - 4
     Anterolateral       Q or QS in I, AVL & V4 - 6
     High Lateral        Q or QS in I & AVL
     Extensive Anterior  Q or QS in I, AVL, V1 - 6
     Inferior (Diaphragmatic) Q or QS in II, III, AVF
     Posterior           Significantly Tall R waves in V1 - 3

MISCELLANEOUS EFFECTS
Drug Effects:
1. Quinidine
     Prolonged QT interval is the hallmark
     U wave
     ST segment depression
     W T wave
     Wide notched P wave
Note: Other drugs that can prolong QT interval
     Procainamide, Disopyramide, Phenothiazine, Tricyclic
2. Digitalis
     ST depression with a U shaped configuration
     T wave flattening & Inversion
     Prolongation of P-R interval
     Shortening of Q-T interval 
** Toxicity = Development of dysrhythmia
     Classic = PAT, Double or Triple AV junctional, Bidirectional V-Tach
     Common = PVC's, Ventricular Bigeminy, Nonparoxysmal junction
          tachycardia
3. Digitalis & Quinidine Combined = Closely resembles Hypokalemia 

Electrolyte Abnormalities
1. Potassium
     Hypokalemia = Flattening of T wave & development of prominent U wave
     Hyperkalemia = T wave tenting, Prolonged P-R interval, Shortening of Q-T
          interval, Decreased P wave height (may disappear)
2. Calcium
     Hypocalcemia = Prolongation of Q-T interval 
          ** Corrected QT = Q-T measured / RR interval
         T waves usually normal but can become inverted if severe hypocalcemia  Hypercalcemia = Shortened Q-T interval

Other Conditions:
1. Pericarditis
     ST elevation with a flat or upward concavity
     No significant Q waves
2. Hypothermia
     Sinus Bradycardia
     Prolongation of all intervals
     Atrial Fibrillation or Flutter
     J wave =pointed elevation of the initial portion of the ST segment @ J point
3. Ventricular Aneurysm
     Persistent Current of Injury Pattern (Persistent St elevation)
4. Pulmonary Embolism (Not specific use in conjunction with other observations)
     Sinus Tachycardia
     RAD
     RAH
     Inverted T waves in V1 - 3
     Pseudo-Diaphragmatic MI pattern
          Q wave, ST elevation, & T wave inversion in III only
          Deeps S Wave in II
          Absent Q wave in AVF
     S1,Q3,T3 inverted Pattern
     S1, S2, S3 = prominent S waves in V1 - 3
     Prominent S waves in V5 & V6
     Transient RBBB at onset
5. Wolfe-Parkinson White- Syndrome
     Delta Wave
     Short P-R interval (<0.12)
     Prolonged QRS (> 0.10)
6. Lown-Ganong-Levine Syndrome
     Short P-R interval in all leads
     No Delta Waves
     Intermittent supraventricular tachycardia
7. Subarachnoid Hemorrhage/ CVA
     Deeply inverted, wide T waves with diffuse distribution
     Non-specific ST-T changes
     Prolonged QT interval
     Prominent U wave
     Supraventricular Tachycardia





                       RHYTHM VARIATIONS
     
NSR Criteria:
     1. P waves of sinus origin (P axis 0 - +90)
     2. Constant P wave configuration in a given lead
     3. Constant and normal P-R interval (0.12 - 0.20 sec)
     4.  Rate between 60 and 100 beats per min
     5.  Constant P-P Interval
     6.  Every P has a QRS and every QRS has a P

SUPERVENTRICULAR DYSRHYTHMIA
1. SA Block
     Dropped P waves (non conducted; QRS missing too)
     SA Wenckebach: Shortening of PP interval leading to dropped P wave
     Type II: Absent P wave seen as an exact multiple of the other sinus cycles
     ** Returns in Phase 

2. Sinus Arrest
     Absence of P waves & QRS complex
     Returns out of phase     
          Presence of escape beats after initial pause

3. PAC (Premature Atrial Complexes)
     Premature ectopic P wave
          P' wave appears different from normal P waves
     Incomplete compensatory pause
     Normal QRS


4.  Atrial Tachycardia (run of 6 or more PAC)
     Atrial rate of 160 - 240 beats/min
     First beat is early
     Ectopic P waves look the same as each other but differ in appearance from
          sinus P waves
     Regular constant P-R interval
     Normal QRS
    *** Paroxysmal Atrial Tachycardia - A Tach with sudden onset & abrupt ending

5.  Multifocal Atrial Tachycardia (run of 6 or more PAC from different atrial foci)
     Atrial rate of 100 - 200 beats/min
     First beat is early
     Ectopic P waves differ in appearance from each other ( 3 or more ectopic
          foci) & differ in appearance from sinus P waves
     irregular r P-P interval
     Irregular P-R interval
     Nonconducted ectopic P waves may occur
     Normal QRS

VENTRICULAR DYSRHYTHMIA

1. Premature Ventricular Complexes (PVC) 
     P wave usually lost (unless retrograde conduction- inverted P after PVC)
     Widened & Bizarre QRS
     T Waves opposite in direction to QRS complexes
     Obscured S-T segments
     No measurable P-R interval    

Types OF PVCs  
     Uniform - all PVCs from same focus & are identical
     Multifocal - Different foci & QRS complexes have different appearance
     Interpolated - Located between 2 normal sinus beats without compensatory
          pause
     Malignant - R on T - quickly degenerates into V-Fib
     Couplets- 2 identical PVCs that occur back to back
     Bigeminy - repeating pattern of 1 normal beat followed by PVC
     Trigeminy - PVC after 2 normal beats or normal beat followed by 2 PVCs
Pauses:
     Full Compensatory - interval between QRS preceding PVC and one
          following PVCs is 2x that of normal cycle
     Partial Compensatory Pause - Interval is < 2x normal cycle

2. Ventricular Tachycardia
     Run of 3 or more PVCs
     1 st beat is early
     Rate 100 - 220
     No ectopic P waves
     No measurable P-R interval
     Wide, bizarre QRS (>0.12sec)
     LAD in 75 - 80% of patients
     Slightly irregular rate

3. Ventricular Flutter
     No recognizable atria activity
     Wide QRS
     Sine Wave appearance



ATRIO-VENTRICULAR IRREGULARITIES AND BLOCKS

1. Atrioventricular Dissociation
     Atria & ventricles beat regularly but independently of each other
     Regular P-P intervals
     Regular R-R intervals
     No relationship between P-P & R-R intervals
     No relationship between P & QRS complexes

2. First Degree AV Heart Block
     Fixed prolonged P-R interval > 0.20 in adults & > 0.18 in kids
     Constant P-R interval
     Regular rhythm
     Normal P waves
     Normal QRS
3. 2nd Degree Heart Block
     Wenckebach (Mobitz Type I) 
          Progressive lengthening of P-R interval until QRS is dropped
          Shortening of R-R interval
          Normal P Waves & QRS Complexes
      Infranodal Block (Mobitz Type II)
          Constant P-R in conducted beats
          Widened QRS due to conduction delay
          Occasional dropped QRS-T complex
          Constant R-R intervals in conducted beats
          P-P interval containing non-conducted P waves equal to 2 normal P-P intervals

4. 3rd Degree Heart Block (Complete Heart Block)
     Independent atrial & ventricular pacing
     P-P intervals regular
     R-R intervals regular
     No relationship between P-P & R-R intervals
     Ventricular rate usually < 40