EKG Cards Flashcards
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Left Anterior Fascicular Block
* Slightly prolonged QRS duration (Not quite 120 msec or < 3 small boxes)
* Left axis deviation
* qR complex in leads I and aVL (Depolarization going towards these leads)
* rS complex in leads II, III, and aVF (Depolarization going away from these leads)
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Left Anterior Fascicular Block
ECG Criteria
* Left axis deviation (usually -45 to -90 degrees)
* qR complexes in leads I, aVL
* rS complexes in leads II, III, aVF
* Prolonged R wave peak time in aVL > 45ms
In LAFB, the QRS voltage in lead aVL may meet voltage criteria for LVH (R wave height > 11 mm), but there will be no LV strain pattern.
Identify this EKG.
Left Anterior Fascicular Block
ECG Criteria
* Left axis deviation (usually -45 to -90 degrees)
* qR complexes in leads I, aVL
* rS complexes in leads II, III, aVF
* Prolonged R wave peak time in aVL > 45ms
In LAFB, the QRS voltage in lead aVL may meet voltage criteria for LVH (R wave height > 11 mm), but there will be no LV strain pattern.
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Bifascicular block (RBBB w/ LAFB)
Clinically, bifascicular block presents with one of two ECG patterns:
- Right bundle branch block (RBBB) with left anterior fascicular block (LAFB), manifested as left axis deviation (LAD)
- RBBB and left posterior fascicular block (LPFB), manifested as right axis deviation (RAD) in the absence of other causes
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Bifascicular Block (RBBB w/ LPFB and RAD)
Clinically, bifascicular block presents with one of two ECG patterns:
- Right bundle branch block (RBBB) with left anterior fascicular block (LAFB), manifested as left axis deviation (LAD)
- RBBB and left posterior fascicular block (LPFB), manifested as right axis deviation (RAD) in the absence of other causes
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Bifascicular Block (RBBB w/ LPFB and RAD)
Clinically, bifascicular block presents with one of two ECG patterns:
- Right bundle branch block (RBBB) with left anterior fascicular block (LAFB), manifested as left axis deviation (LAD)
- RBBB and left posterior fascicular block (LPFB), manifested as right axis deviation (RAD) in the absence of other causes
EKG:
* RBBB with wide QRS, slurred S wave in lead I and slurred R in V1.
* Right axis deviation (dominant negative deflection in leads I and aVl) with dominant positive deflection in aVf along with rS pattern in lead I and qR pattern leads III and aVf, suggesting left posterior fascicular block.
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Bifascicular block (RBBB w/ LAFB)
Clinically, bifascicular block presents with one of two ECG patterns:
- Right bundle branch block (RBBB) with left anterior fascicular block (LAFB), manifested as left axis deviation (LAD)
- RBBB and left posterior fascicular block (LPFB), manifested as right axis deviation (RAD) in the absence of other causes
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Right Bundle Branch Block
* QRS duration > 120ms
* RSR’ pattern in V1-3 (“M-shaped” QRS complex)
* Wide, slurred S wave in lateral leads (I, aVL, V5-6)
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Right Bundle Branch Block
* QRS duration > 120ms
* RSR’ pattern in V1-3 (“M-shaped” QRS complex)
* Wide, slurred S wave in lateral leads (I, aVL, V5-6)
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Left Bundle Branch Block (INCOMPLETE)
* QRS duration ≥ 120ms (QRS duration <120 ms is considered INCOMPLETE LBBB)
* Dominant S wave in V1
* Broad monophasic R wave in lateral leads (I, aVL, V5-6)
* Absence of Q waves in lateral leads
* Prolonged R wave peak time > 60ms in leads V5-6
* Note: Incomplete LBBB is diagnosed when typical LBBB morphology is associated with a QRS duration < 120 ms.
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Left Bundle Branch Block (COMPLETE)
* QRS duration ≥ 120ms
* Dominant S wave in V1
* Broad monophasic R wave in lateral leads (I, aVL, V5-6)
* Absence of Q waves in lateral leads
* Prolonged R wave peak time > 60ms in leads V5-6
* Note: Incomplete LBBB is diagnosed when typical LBBB morphology is associated with a QRS duration < 120 ms.
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True trifascicular block refers to the presence of conduction delay in all three fascicles below the AV node (RBBB, LAFB, LPFB), manifesting as bifascicular block and 3rd degree AV block. One of two ECG patterns is present:
3rd degree AV block + RBBB + LAFB or;
3rd degree AV block + RBBB + LPFB
Other rare indicators of trifascicular block include:
Normal sinus rhythm with alternating LBBB/RBBB
RBBB with alternating fascicular blocks on a beat-to-beat basis
These herald impending failure of all three fascicles and associated 3rd degree AV block
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ECG Features: PR interval > 200 milliseconds (five small squares)
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Sinus Bradycardia w/ 1st degree AV Block (note that PR Interval is >300 ms)
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AV Block: 2nd Degree, Mobitz I (Wenckebach Phenomenon)
Progressive prolongation of the PR interval culminating in a non-conducted P wave:
PR interval is longest immediately before dropped beat
PR interval is shortest immediately after dropped beat