ECG: Bundle Branch Blocks/Hemiblocks (Johnston) Flashcards
Define intrinsic deflection (ID)
Time lapse from beginning of the QRS to the peak of the R wave
During ventricular depolarization the septum is activated in which direction?
From L –> R
Which feature of the QRS complex is characteristic of bundle branch blocks?
Wide QRS (>0.12 sec) = >3 small squares
List 6 causes of rsR’ variants in V1-V2
- Normal
- Pectus or straight back
- RV diastolic volume overload
- WPW syndrome
- RVH
- Duchenne dystrophy
What are 4 underlying etiologies where LBBB is more likely to occur?
- HTN
- Ischemia
- Aortic stenosis
- Cardiomyopathy
LBBB with RAD is usually due to what?
Congestive Cardiomyopathy
In LBBB which 2 leads share similar features with V6?
Lead I and AVL (point in similar direction)
If T wave polarity is in the same direction of the QRS complex, it is called what type of T wave change?
Usually due to what?
- Primary T wave change
- Due to ischemia
What type of block is this?
Left Anterior Hemiblock
What type of axis deviation is associated with a left anterior hemiblock and a left posterior hemiblock?
- LAH is associated with LAD
- LPH is associated with RAD
What is the morphology of the Q and R waves associated with a left anterior hemiblock and in which leads?
- Small Q in leads I and aVL
- Small R in leads II, III, and aVF
What is the morphology of the Q and R waves associated with a left posterior hemiblock and in which leads?
- Small R in leads I and aVL
- Small Q in leads II, III, and aVF
What is the typical etiology of left anterior hemiblocks?
- Disease in conduction system
- Often associated w/ MI (LAD - occlusion)
Interpret this EKG
Left Anteior Hemiblock
Interpret this EKG
Left Anterior Hemiblock
Interpret this EKG
Bifascicular block: RBBB + Left Anterior Hemiblock
Interpret this EKG
Left Posteior Hemiblock
Interpret this ECG (i.e., axis and rhythm)
RAD w/ left posterior hemiblock and RBBB
