EKG Guidelines

Question 1

Define anterolateral MI, age recent or probably acute?

Answer 1

• Pathological Q waves (must be greater than or equal to 30 ms wide and 0.1mV deep in amplitude or QS complex) in anterolateral leads V3-V6
• Evidence of acute or evolving myocardial injury (i.e. ST-elevation in two contiguous leads greater than or equal to 2mm in men or 1.5mm in women in V3 and/or 1mm in V4-V6)

***Only use this diagnosis when both are present:

• pathological Q waves
• ST-elevation are present

Question 2

What EKG finding can demonstrate “pseudo” anterior MI (q-waves)?

Answer 2

LAFB

• low anterior forces or “pseudo” anterior MI

Question 3

EKG DDx:

• Lead I - Inverted P-wave

Answer 3

• PAC’s
• Atrial Rhythm
  
  • AT
  • MAT
  • SVT
• PJC’s
• PVC’s with retrograde activation
• Dextrocardia
  
  • (inverted P-QRS-T in leads I and aVL)
  • (reverse R wave progression in the precordial leads)
• Reversal of right and left arm leads
  
  • (inverted P-QRS-T in leads I and aVL)
  • (normal R wave progression in the precordial leads)

Question 4

Define Inferior MI

Answer 4

• Pathological Q waves in at least in at least 2 inferior leads
• Evidence of acute or evolving myocardial injury
  
  • ST elevation greater than or equal to 1 mm in two contingous inferior leads

Question 5

Define LAFB

Answer 5

• LAD ( -45 to -90)
• qR complexes in I and aVL
• rS complexes in III
• Prolonged R wave peak time in aVL ( > 45 ms)

Question 6

What are EKG conditions/changes that interfere with the EKG diagnosis of posterior MI?

Answer 6

• RVH
• WPW
• RBBB

Question 7

Define ST and/or T wave abnormalities suggesting myocardial ischemia?

Answer 7

• Greater than 1mm of horizontal or downsloping ST-T segment depression

and/or

• T wave inversion greater than or equal to 2mm

Question 8

How to differentiate the direction of macro re-entry in atrial flutter?

Answer 8

• Flutter wave amplitude in leads aVF and I
  
  • aVF / lead I > 2.5 = counter-clockwise
  • aVF / lead I < 2.5 = clockwise

Question 9

Aberrantly conducted PAC’s are most often this pattern

Answer 9

RBBB

Question 10

What is the differential for irregularly, irregular SVTs?

Answer 10

• Differential Dx:
  
  • MAT
  • ST with PAC’s (frequent)
  • A-fib (coarse)

Question 11

What is required to code for RAE?

Answer 11

NSR

Question 12

What are additional pitfalls to avoid in presence of LAFB?

Answer 12

• May result in a false-positive diagnosis of LVH based on voltage criteria in lead I or aVL
• Can mask presence of inferior wall MI
• Rarely seen in normal hearts

Question 13

True/False:

Posterior MI is usually seen in the setting of acute inferior or inferolateral MI, but may also occur in isolate lateral MI

Answer 13

True

Question 14

Define 2nd degree AV block - Mobitz II?

What are the associated features?

Answer 14

• Regular sinus or atrial rhythm with intermittent non-conducted P waves and no evidence of PAC’s
• Constant P-R interval exists with all conducted beats
• The R-R interval of non-conducted beat is equal to two P-P intervals
• Site of block: more commonly (80%) distal to the AV node (intra- or infra-Hisian) –> wide QRS ( > 120ms)
• Often show signs of conduction system disease (BBB or fascicular block)

Question 15

Define left anterior fascicular block (LAFB) on EKG

Answer 15

• Left axis deviation (usually more negative than -45)
• Slight widening of the QRS complex
• Prominent S wave in V5 and V6

Question 16

Define Anterior or anteroseptal, age recent or probably acute?

Answer 16

• Pathological Q waves (must be greater than 30ms wide and 0.1mV deep in amplitude or QS complex) in anterior (V3-V4) or anteroseptal (V1-V3) leads; Q wave width may only be 20ms wide in V2-V3
• Evidence of acute or evolving myocardial injury (i.e. ST-elevation in two contiguous leads greater than or equal to 2mm in men or 1.5mm in women in V2-V3 and/or 1mm in other anterior or atneroseptal leads)

***Only use this diagnosis when both are present:

• pathological Q waves
• ST-elevation are present

Question 17

What is the diagnosis that should be considered?

• Atrial flutter
• 3rd degree heart block
• Junctional tachycardia

Answer 17

Digoxin toxicity

Question 18

What is the EKG criteria for LPFB?

Answer 18

• RAD ( > +90 degrees)
• Small R waves with deep S waves (rS complexes) in leads I and aVL
• Small Q waves with tall R waves (qR complexes) in leads II, III, aVF
• QRS normal or slightly prolonged
• Prolonged R wave peak time in aVF
• Increased QRS voltage in limb leads
• No evidence of RVH or any other cause of RAD

Question 19

Define posterior MI

Answer 19

• V2-V3
  
  • dominant R waves (R wave > S wave with and R wave duration ≥ 40 msec)
  • ST-depression ≥ 1 mm with upright T-waves

Question 20

What are the EKG criteria for LAFB?

Answer 20

• LAD (usually between -45 and -90 degrees)
• Small Q waves with tall R waves (qR complexes) in leads I and aVL
• Small R waves with deep S waves (rS complexes) in leads II, III, aVF
• QRS duration normal or slightly prolonged (80-110ms)
• Prolonged R wave peak time in aVL > 45ms
• Increased QRS voltage in the limb leads

Question 21

Define 1st degree AV block?

When is this seen (acquired)?

Answer 21

• P-R interval greater than or equal to 200msec
• Each P-wave is followed appropriated by a QRS
• High vagal tone (during sleep)
• Treatment with BB or CCB’s

Question 22

What are causes of LBBB?

Answer 22

• CAD
• HTN
• Aortic stenosis
• Anterior MI
• Dilated Cardiomyopathy
• Primary degenerative disease of the conducting system (Lenegre disease)
• Hyperkalemia
• Digoxin toxicity

Question 23

Why does SVT typically occur with aberrant conduction in RBBB morphology?

Answer 23

• Right bundle has a longer refractory period than the left bundle
• Aberrant conduction usually travels down the left bundle
• Resulting in QRS morphology with RBBB pattern

Question 24

What are the EKG diagnostic criteria of LBBB?

Answer 24

• QRS duration > 120ms
• Dominant S wave in V1
• Broad monophasic R wave in lateral leas (I, aVL, V5-V6)
• Prolonged R wave peak time > 60ms in left precordial leads (V5-V6)
• Associated features
  
  • Appropriate discordance
    
    • ST segments and T waves always go in the opposite direction to the main vector of the QRS complex
  • Poor R wave progression the precordial leads
  • Left axis deviation

Question 25

Define EKG criteria for WPW?

Answer 25

* short PR interval ( \< 120ms in adults and \< 90ms in children during sinus rhythm) * Slurring of QRS complex (delta wave), resulting in the QRS being \> 120 ms in adults and \> 90 ms in children * widened QRS results from fusion of two electrical impulses, one through the normal AV node and the other through the bypass tract * Secondary ST-T wave changes * ST-T segment deviation opposite in direction of main QRS deflection * Pseudo-infarction pattern can be seen in up to 70% of patients * due to negatively deflected delta waves in the inferior/anterior leads ("pseudo-Q waves"), or as a prominent R wave in V1-V3 (mimicking posterior infarction)

Question 26

Differentiate MAT from: * ST with PAC's * A-fib

Answer 26

* MAT (from ST with PAC's) * will not demonstrate a **single, dominant, atrial pacemaker** * MAT (from A-fib) * **isoelectric baseline between P-waves**

Question 27

# Define 3rd degree (complete) AV block? When can this be seen? adenosine

Answer 27

* Complete failure of atrial impulses to pass through the AV node and stimulate ventricular activity * Results in constant P-P intervals, but the atrial and ventricular rhythms are independent of each other * Atrial rate is typically faster than the ventricular rate, as the ventricular rate is driven by either a junctional rhythm, ventricular escape complex, or a ventricular pacemaker * MI, degnerative diseases (Lev's, Lenegre's), infiltrative diseases (sarcoidosis, amyloidosis), digitalis toxicity, endocarditis, marked hyperkalemia, Lyme disease, myocardial contusion, acute rheumatic fever, severe valvular disease.

Question 28

EKG DDx: * Lead II - Multiple P wave morphologies

Answer 28

* Wandering atrial pacemaker (rate \< 100 bpm) * MAT (rate \> 100 bpm) * Sinus or atrial rhythm with multifocal PAC's

Question 29

# Define 2nd degree AV block - 2:1? When can this be seen?

Answer 29

* Regular sinus or atrial rhythm with two P waves for every QRS complex (only every other P wave is conducted) * Can be secondary to Mobitz type I or Mobitz Type II AV block

Question 30

# Define 2nd degree AV block - Mobitz 1 (Wenckebach)? When can this be seen?

Answer 30

* Progressive prolongation of the PR interval until a P wave is blocked * R-R interval of non-conducted beat must be less than 2 times the P-P interval (otherwise, high degree of AV block exists) * Will give the appearance of group beating * Site of block: usually in the AV node * High vagal tone, AV nodal blocking agents (BB, CCB's)

Question 31

Define Inferior MI, age recent or probably acute?

Answer 31

* Pathological Q waves (must be greater than or equal to 30ms wide and 0.1mV deep in amplitude or QS complex) in at least two inferior (II, III, or aVF) leads * Evidence of acute or evolving myocardial injury (i.e. ST-elevation greater than or equal to 1 mm in two congiusou inferior leads) \*\*\*Only use this diagnosis when _both_ are present: * pathological Q waves * ST-elevation are present

Question 32

Describe the different types of WPW

Answer 32

* Type A: positive delta wave in all precordial leads with R/S \> 1 in V1 * Type B: negative delta wave in leads V1 and V2

Question 33

Classic features for a rhythm originating in ventricular myocardium

Answer 33

* Wide QRS ( \> 0.28s) * R wave in lead aVR ("northwest axis") * capture complexes * \> 100 ms from onset of R wave to the nadir of the S wave in \> 1 chest lead * atypical RBBB = R \> R' in V1 * R wave usually \< R'

Question 34

What is the term for rhythm of ventricular origin with HR \< 100 bpm?

Answer 34

AIVR

Question 35

How do you distinguish between: * coarse A-fib * MAT

Answer 35

MAT → isoelectric baseline between P-waves

Question 36

Describe differences in etiologies of QT prolongation:

Answer 36

QT prolongation due to: * **Hypocalcemia → normal T waves** * ST lengthening without a change in T wave duration or morphology * **Medications or Genetic disorders → complex T wave morphology**

Question 37

What is “T-wave memory?" When is it seen?

Answer 37

* TWI's occurring in ECG of patients in their NSR when they had abnormal ventricular activation transiently due to various causes * Causes: * RV pacing * VT * intermittent LBBB * intermittent WPW syndrome

Question 38

Differentiate location of conduction delay in 1st degree AV block

Answer 38

* Narrow QRS * conduction delay typically occurs in the AV node * usually due to: * medications that delay AV conduction (BB, CCB, Digoxin) * normal physiology / High vagal tone (high fitness levels, nausea, pain, sleep) * Wide QRS * may represent conduction delay in the His-Purkinje system * usually in conjunction with RBBB, LAFB, LPFB, LBBB

Question 39

Posterior MI cannot be diagnosed in the presence of this?

Answer 39

RBBB

Question 40

What is one key finding when coding for acute inferior Q wave MI?

Answer 40

aVL * there will virtually always be **reciprocal ST segment depression** * even if the ST segment elevation in other leads is minimal

Question 41

What is one key finding when coding for acute lateral Q wave MI?

Answer 41

aVF * there will virtually always be **reciprocal ST segment depression** * even if the ST segment elevation in other leads is minimal

Question 42

What is required for the diagnosis? * Acute cor pulmonale including pulmonary embolus

Answer 42

* Symptoms of acute decompensation (sudden onset dyspnea, collapse) * EKG findings: * RV strain pattern (ST-depression + TWI in R precordial leads) * Rhythm change (ST, A-fib)

Question 43

When evaluating for signs of acute or active CAD? * ST-T changes suggesting myocardial ischemia

Answer 43

* significant ST depression is observed * often with concomitant inverted or biphasic T waves * but **without abnormal Q waves**

Question 44

When evaluating for signs of acute or active CAD? * ST-T changes suggesting myocardial injury

Answer 44

* ST elevation * with or without abnormal Q waves

Question 45

When evaluating for signs of acute or active CAD? * Old or age indeterminate

Answer 45

* abnormal Q waves are observed in 2 or more contiguous leads * not associated with ST-elevation

Question 46

What distinguishes acute or recent? * Anterior * Anteroseptal

Answer 46

ST elevation in **lead V1**

Question 47

What distinguishes age acute or recent? * Lateral * Anterolateral

Answer 47

* Anterolateral * must show \> 1 mm ST-elevation in at least two contiguous leads * **V4-V6** * Lateral * must show \> 1 mm ST-elevation in at least two contiguous leads * **I, aVL**

Question 48

Define Juvenile T-waves, normal variant

Answer 48

* TWI - localized to R precordial leads (V1 - V3) * shallow in depth * seen in younger, healthy individuals * typically females * Upright T waves in I, II, V5, V6

Question 49

What is a major key to differentiating wide QRS tachycardias? * VT * SVT with aberrancy

Answer 49

Evaluate how tachycardia begins and ends * VT * starts - PVC * ends - gradual slowing of the rate and then termination * SVT with aberrancy * starts - PAC with long PR interval + narrow QRS complex * ends - narrow complexes at a similar rate and retrograde P waves

Question 50

# Define: * Poor R-wave progression

Answer 50

* R wave in V3 \< 3 mm or * R/S transition zone in V5 or V6 * first precordial lead with R/S \> 1

Question 51

What is the differential diagnosis: * Dominant R wave in V1

Answer 51

* Normal * RBBB * RVH * Dextrocardia * Limb lead reversal * Pacing * WPW * Duchenne muscular dystrophy * HCM * Posterior MI