ECG abnormalities 1 Flashcards
Chamber enlargement
- RA -> proximal part of P wave
- LA -> distal part of P wave
- RV -> R wave
- LV -> S wave
Atrial enlargement which leads to look for especially
II
V1
Algorithm of evaluation the right atrial enlargement
-> especially in II and V1
- General contour
1) peaked proximal part of P wave (A-like appearance)
- > it’s called P PULMONALE - P wave duration -> no change
- Amplitudes of P wave -> increased (>0.25 mV in II and > 0.15 in positive phase of V1)
Algorithm of evaluation the left atrial enlargement
-> especially in II and V1
- General contour
1) notch in the middle of P wave followed by 2nd hump (M-like appearance)
- > called P MITRALE - P wave duration -> prolonged >0.12 s
and in V1 negative portion of P wave > 0.04 s - Amplitudes of P wave -> usually doesn’t increase but in V1 -> increased negatively directed portion >0.1 mV
- Axis -> may cause a slight leftward shift in frontal plane (but usually it remains normal)
- > in extreme LAE P wave amplitude May increase and the terminal portion of P wave may become negative in leads II, III and aVF
Algorithm of evaluation the left and right (bilateral) atrial enlargement
- Characteristics of RAE and LAE
Other criteria that may suggest LAE
- Duration of terminal negative P-wave deflection in lead V1 >0.04 s
- Amplitude of terminal negative P-wave deflection in lead V1 >0.1 mV
- Duration between peaks of P-wave notches >0.04 s
- Maximal P-wave duration >0.11 s
- Ratio of P-wave duration to RR segment duration >1:1.6
Ventricular enlargement which leads to look for especially
I
V1
I and V1 QRS amplitude in ventricular enlargement (suggestion, severe)
- LVE
- > V1 -> increase in S wave amplitude
- > V6 -> increase in R amplitude
- > I and aVL-> increase in R wave amplitude - RVE
- > V1 -> increase in R amplitude
- > V6 -> increase in S amplitude - LVE + RVE
- > hybrid of LVE and RVE
Right ventricular enlargement ecg criteria
- Mild no ECG change or axis move rightward (can be S>R in lead I)
- Moderate
- > I - RS (small R),
- > increased R in V1 (RS, R>S)
- > axis may or may not be rightward
- > S wave in V6 - Severe
1) I - rS (small R, R negativity of ST segment and T wave (delayed repolarization, right ventricular strain)
Right ventricular dilation
- QRS axis shifts rightward
- RSR’ appears in V1 and V2
- QRS duration can be prolonged
- Occurs during compensation or volume overload or after it’s hypertrophy fails to compensate for pressure overload
Left ventricular dilation
- Increase of the leftward and posteriorly directed QRS waveforms
- S wave amplitudes are increased in V1-V3
- R wave amplitudes are increased in left-leaning (I, aVL, V5-6)
- T waves amplitudes can be increased in the same leads and direction as amplitude of QRS complex
- > it can be also directed away from QRS complex -> indicating left-ventricular strain - Occurs during compensation or volume overload or after it’s hypertrophy fails to compensate for pressure overload
Left ventricular hypertrophy
- Prolonged intrinsicoid deflection
- Negative ST and T segment (delayed repolarization, reverse repolarization-> from endocardium to epicardium) in leftward-oriented leads (i.e. V5, V6)
- > left-ventricular strain - Increase of the leftward and posteriorly directed QRS waveforms
- S wave amplitudes are increased in V1-V3
- R wave amplitudes are increased in left-leaning (I, aVL, V5-6)
Ventricular hypertrophy algorithm
- General contour
1) prolongation of the intrinsicoid deflection-> can be mid-QRS notches
2) ST segment slope in the direction of the T wave-> when in rightward precordial leads -> called right-ventricular strain, in LV analogously - Duration of QRS complex
1) LVH -> May cause prolongation (progressive, usually slower than in LBBB)
2) RVH -> usually normal duration (but in dilation can be slight increase) - Amplitudes
1) see criteria - Axis
A) frontal
1) RVH -> rightward or vertical
2) LVH -> leftward
Ventricular hypertrophy criteria
- RVH
1) Butler-Leggett formula
2) Sokolow-Lyon criteria - LVH
1) Romhilt-Estes scoring system
2) Sokolow-Lyon criteria
3) Cornell Voltage criteria
Butler-Leggett formula for RVH
A+R-PL ≥ 0.70 mV in RVH
A (anterior) -> tallest R or R’ amplitude in V1 or V2
R (rightward) -> deepest S amplitude in I or V6
PL (posterior lateral) -> S amplitude in V1
Sokolow-Lyon criteria for RVH
R-> R wave amplitude in V1
S -> S wave amplitude in V5 or V6 (bigger)
In RVH
R+S ≥ 1.10 mV
Romhilt-Estes scoring system for LVH
- (3 points)
R or S wave in any limb ≥ 2 mV
or S in lead V1 or V2 ≥ 2 mV
or R in lead V5 or V6 ≥ 3 mV - Left ventricular strain (ST and T in opposite direction to QRS complex)
1) without digitalis -> 3 points
2) with digitalis -> 1 point - (3 points)
Left atrial enlargement (terminal negativity of P wave in V1 is:
-> ≥0.1 mV in amplitude AND
-> ≥0.04 s in duration - (2 points)
Left axis deviation ≥-30 degrees - (1 point)
QRS duration ≥ 0.09 s - (1 point)
Intrinsicoid deflection in V5 or V6 ≥0.05 s
Max 13 points
LVH ≥5 points
4 points-> probably LVH
Sokolow-Lyon criteria for LVH
R-> R wave amplitude in V5 or V6
S -> S wave amplitude in V1
In LVH
R + S ≥ 3.50 mV
or
R ≥ 2.6 mV
Cornell Voltage criteria for LVH
R-> R wave amplitude in aVL
S -> S wave amplitude in V3
LVH when
- Females:
R + S ≥ 2 mV - Males
R + S ≥ 2.8 mV
Conditions that can mimic or complicate the diagnosis of bundle-branch block (BBB)
- LVH or RVH
- Myocardial ischemia or infarction
- Accessory pathways for conduction from the atria to the ventricles
BBB main changes and the most important lead
V1:
- RBBB -> right ventricular activation after left -> R’ wave in V1
- LBBB -> postponed LV activation -> abnormally prominent S wave in V1 + mid-QRS notching in I, aVL, V1, V2, V5 or V6
Division of His bundle
- RBB -> right bundle branch
- LBB -> left bundle branch (division after 1-2 cm)
1) LAF -> left anterior fascicle
2) LPF -> left posterior fascicle
Division of intraventricular blocks
- Unifascicular blocks-> unilateral-> isolated:
1) LAFB -> common
2) LPFB -> rare
3) RBBB -> common - Bifascicular blocks
1) LBBB (LAFB + LPFB)
2) RBBB + LAFB
3) RBBB + LPFB - Trifascicular blocks
1) LBBB + RBBB
Criteria for RBBB
- QRS ≥ 0.12 s (incomplete ≥ 0.11 s)
- V1 or V2: M-shaped QRS (RSR’) and
- I and V6: S wave wider than R wave or ≥ 0.04 s)
- Possible changes of ST (oblique decrease) and T (negative) -> V1, V2, V3
- > (if not -> consider myocardial infarction) - Late intrinsicoid in V1 R’ peak or late R peak, >0.05 s
LAFB criteria
-> all
- Left axis deviation (-45 to -90 degrees)
- Small Q (qR) in aVL and I
- Small R (rS) in III and aVF
- QRS <0.12 s
- Late intrinsicoid deflection in aVL >0.045 s (qR)
(6. Often increased QRS voltage in limb leads)
LPFB criteria
-> all
- Right axis deviation (90 to 180 degrees)
- Small Q (qR) in III and aVF and
- Small R (rS) in I and aVL
- QRS <0.12 s
- Late intrinsicoid deflection in aVF (>0.045 s)
- No evidence of RVH
(7. Often increased QRS voltage in limb leads)
LBBB criteria
- QRS ≥ 0.12s (incomplete ≥ 0.11 s)
- Mid QRS notching/ slurring in two of the left-leaning leads (I, aVL, V5, V6)
- QS or rS in V1-V3
- V5,V6 -> late (>0.06 s) intrinsicoid
- Possible changes in ST and T opposite to QRS amplitude (if not -> consider myocardial infarction)
- Always look for STEMI criteria with LBBB
LBBB incomplete criteria
- QRS duration ≥ 110 ms i < 120 ms.
- Wide, peaky R wave, sometimes with notch in leads I, V5 or V6
- Intrinsicoid deflection in V5, V6 > 60 ms
- No q waves in leads I, V5, V6.
RBBB + LAFB
- Bilateral block
- Common sign of a large anteroseptal infarction
- Criteria:
1) late prominent R or R’ in V1 -> increased intrinsicoid deflection (RBBB)
2) initial R and prominent S in II, III, aVF of LAFB
3) duration of QRS ≥ 0.12 s
4) axis -> leftward (between -45 and -120 degrees)
RBBB + LPFB
- Rarely
- Criteria
1) no RVH
2) V1 -> changes typical for RBBB
3) I, aVL -> changes typical for LPFB (initial R and prominent S)
4) QRS duration ≥ 0.12 s
5) frontal axis ≥ +90 degrees
Differentiating LBBB and LVH
- The greater the amplitude of QRS complex-> the more likely is LVH
- The greater the duration of QRS complex-> the more likely is LBBB
- Klein criteria -> in the presence of LBBB either of following criteria is associated with LVH:
1) S wave in V2 amplitude + R wave in V6 > 4.5 mV
2) Evidence of atrial enlargement with a QRS complex duration > 0.16 s
Causes of BBB
- Fibrosis of Purkinje fibers (Lenegre disease or Lev disease)
- Chagas disease (usually RBBB with LAFB)
- Distention of RV -> volume overload (RBBB)
- Right heart catheterization (catheter tip induced trauma) -> RBBB
- Myocardial infarction
Other serious cardiac diseases
-> after many years (>10) it can turn into the AV block
BBB coronary artery perfusion
- LAD -> RBB and LAF in 90% of the cases
- RCA -> LPF in 90%
-> dual arterial supply of LAF and LPF in 40-50%
Intermittent BBB
- Occurs usually before permanent block
- Can occur in tachycardia-> tachycardia-dependent BBB
- > slowing the heart -> normal conduction
- > because RR shortens -> descending impulse finds one of the bundle branches still in refractory period - Can be also bradycardia-dependent BBB
1) rare
2) pairs of beats -> normal with shorter cycle and BBB with longer cycle
WPW syndrome
Wolff-Parkinson-White syndrome
- Accessory connection between atria and ventricle -> Kent bundle
- Ventricular preexcitation with symptomatic tachycardia -> usually due to reentry in Kent bundle
Ventricular preexcitation ecg criteria
- PR interval duration < 0.12 s (but in ab to 25% can be normal)
- Delta wave at the beginning of the QRS complex
- QRS > 0.12 s (but in ab to 25% can be normal)
- Changes in ST segment and T wave -> usually opposite side of the QRS complex
ECG localization of Kent bundle -> Rosenbaum classification
- Group A:
- > QRS mainly positive in V1 and V2 -> LA-LV - Group B:
- > QRS mainly negative in V1 and V2 -> RA-RV
ECG localization of Kent bundle -> Milstein’s algorithm
- Negative or isoelectric delta wave in at least one of I, aVL or V6
1) LBBB present -> right anteroseptal (RA) location of Kent bundle
2) no LBBB -> left lateral (LL) - Positive delta wave in all of I, aVL and V6
1) Negative or isoelectric delta wave in at least two of II, III, aVF
1. Positive delta wave in at least one of V1, V2 or V3 -> Posteroseptal (PS)
2. Negative delta wave in all: V1, V2, V3-> right lateral (RL)2) Positive delta wave in at least two of II, III, aVF
1. LBBB present
1) QRS axis > +30 degrees-> right anteroseptal (RAS)
2) QRS axis <= + 30 degrees-> right lateral (RL)2. No LBBB 1) positive delta wave in V1 or V2 -> left lateral (LL) 2) negative delta wave in both V1 and V2 -> undetermined
-> > 90% correctness of localization
Location of Kent bundle
- Left laterally (50%) -> between LA and LV
- Posteriorly between the atrial and ventricular septa (30%)
- Right laterally or anteriorly-> between RA and RV (20%)
Tonkin criteria for localizing the accessory pathway
-> consideration of the vector between point 0.02 s after the onset of delta wave in QRS complex and this onset
Direction of preexcitation
- Rightward-> location LA-LV free wall (100%)
- Leftward and superior -> posterior wall (90%)
- Leftward and inferior -> RA-RV free wall (86%)
Diagnostic procedures when the ventricular preexcitation is suspected in a patient with tachyarrhythmia but no ECG evidence of preexcitation
- Pace the atria electronically at increasingly rapid rates to induce conduction via any existing accessory pathways
- Produce vagal nerve stimulation to impair normal conduction through the AV node
- Infuse digoxin iv. (same purpose as 2)
