EKG Guidelines Flashcards
Define anterolateral MI, age recent or probably acute?
- 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
What EKG finding can demonstrate “pseudo” anterior MI (q-waves)?
LAFB
- low anterior forces or “pseudo” anterior MI
EKG DDx:
- Lead I - Inverted P-wave
- 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)
Define Inferior MI
- 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
Define LAFB
- LAD ( -45 to -90)
- qR complexes in I and aVL
- rS complexes in III
- Prolonged R wave peak time in aVL ( > 45 ms)
What are EKG conditions/changes that interfere with the EKG diagnosis of posterior MI?
- RVH
- WPW
- RBBB
Define ST and/or T wave abnormalities suggesting myocardial ischemia?
- Greater than 1mm of horizontal or downsloping ST-T segment depression
and/or
- T wave inversion greater than or equal to 2mm
How to differentiate the direction of macro re-entry in atrial flutter?
- Flutter wave amplitude in leads aVF and I
- aVF / lead I > 2.5 = counter-clockwise
- aVF / lead I < 2.5 = clockwise
Aberrantly conducted PAC’s are most often this pattern
RBBB
What is the differential for irregularly, irregular SVTs?
- Differential Dx:
- MAT
- ST with PAC’s (frequent)
- A-fib (coarse)
What is required to code for RAE?
NSR
What are additional pitfalls to avoid in presence of LAFB?
- 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
True/False:
Posterior MI is usually seen in the setting of acute inferior or inferolateral MI, but may also occur in isolate lateral MI
True
Define 2nd degree AV block - Mobitz II?
What are the associated features?
- 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)
Define left anterior fascicular block (LAFB) on EKG
- Left axis deviation (usually more negative than -45)
- Slight widening of the QRS complex
- Prominent S wave in V5 and V6
Define Anterior or anteroseptal, age recent or probably acute?
- 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
What is the diagnosis that should be considered?
- Atrial flutter
- 3rd degree heart block
- Junctional tachycardia
Digoxin toxicity
What is the EKG criteria for LPFB?
- 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
Define posterior MI
- V2-V3
- dominant R waves (R wave > S wave with and R wave duration ≥ 40 msec)
- ST-depression ≥ 1 mm with upright T-waves
What are the EKG criteria for LAFB?
- 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
Define 1st degree AV block?
When is this seen (acquired)?
- 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
What are causes of LBBB?
- CAD
- HTN
- Aortic stenosis
- Anterior MI
- Dilated Cardiomyopathy
- Primary degenerative disease of the conducting system (Lenegre disease)
- Hyperkalemia
- Digoxin toxicity
Why does SVT typically occur with aberrant conduction in RBBB morphology?
- 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
What are the EKG diagnostic criteria of LBBB?
- 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
- Appropriate discordance
Define EKG criteria for WPW?
- 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)
Differentiate MAT from:
- ST with PAC’s
- A-fib
- MAT (from ST with PAC’s)
- will not demonstrate a single, dominant, atrial pacemaker
- MAT (from A-fib)
- isoelectric baseline between P-waves
Define 3rd degree (complete) AV block?
When can this be seen?
adenosine
- 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.
EKG DDx:
- Lead II - Multiple P wave morphologies
- Wandering atrial pacemaker (rate < 100 bpm)
- MAT (rate > 100 bpm)
- Sinus or atrial rhythm with multifocal PAC’s
Define 2nd degree AV block - 2:1?
When can this be seen?
- 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
Define 2nd degree AV block - Mobitz 1 (Wenckebach)?
When can this be seen?
- 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)
Define Inferior MI, age recent or probably acute?
- 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
Describe the different types of WPW
- 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
Classic features for a rhythm originating in ventricular myocardium
- 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’
What is the term for rhythm of ventricular origin with HR < 100 bpm?
AIVR
How do you distinguish between:
- coarse A-fib
- MAT
MAT → isoelectric baseline between P-waves
Describe differences in etiologies of QT prolongation:
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
What is “T-wave memory?”
When is it seen?
- 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
Differentiate location of conduction delay in 1st degree AV block
- 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
- may represent conduction delay in the His-Purkinje system
Posterior MI cannot be diagnosed in the presence of this?
RBBB
What is one key finding when coding for acute inferior Q wave MI?
aVL
- there will virtually always be reciprocal ST segment depression
- even if the ST segment elevation in other leads is minimal
What is one key finding when coding for acute lateral Q wave MI?
aVF
- there will virtually always be reciprocal ST segment depression
- even if the ST segment elevation in other leads is minimal
What is required for the diagnosis?
- Acute cor pulmonale including pulmonary embolus
- 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)
When evaluating for signs of acute or active CAD?
- ST-T changes suggesting myocardial ischemia
- significant ST depression is observed
- often with concomitant inverted or biphasic T waves
- but without abnormal Q waves
When evaluating for signs of acute or active CAD?
- ST-T changes suggesting myocardial injury
- ST elevation
- with or without abnormal Q waves
When evaluating for signs of acute or active CAD?
- Old or age indeterminate
- abnormal Q waves are observed in 2 or more contiguous leads
- not associated with ST-elevation
What distinguishes acute or recent?
- Anterior
- Anteroseptal
ST elevation in lead V1
What distinguishes age acute or recent?
- Lateral
- Anterolateral
- 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
Define Juvenile T-waves, normal variant
- 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
What is a major key to differentiating wide QRS tachycardias?
- VT
- SVT with aberrancy
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
Define:
- Poor R-wave progression
- R wave in V3 < 3 mm or
- R/S transition zone in V5 or V6
- first precordial lead with R/S > 1
What is the differential diagnosis:
- Dominant R wave in V1
- Normal
- RBBB
- RVH
- Dextrocardia
- Limb lead reversal
- Pacing
- WPW
- Duchenne muscular dystrophy
- HCM
- Posterior MI
