Transcript Document

Steps for Normal Depolarization
The electrical impulse progress through the RBB
and LBB and Fascicles simultaneously.
• Depolarization of IVS
• Synchronous Depolarization of RV & LV
• Note: The electrical activity generated by the
depolarization of the smaller RV is buried in that
generated by the LV.
Depolarization of Septum
• Depolarization of the Interventricular
Septum of the endocardial to epicardial of
the ventricular wall is call the Ventricular
Activation time (VAT) or the Preintrinsicoid
Deflection (IDT), the duration of the
Intrinsicoid Deflection or the R peak time.
VAT Measurement
• Onset of the QRS complex to the peak of
the last R wave in the QRS complex.
• Normally less than .04 second in V1 or V2
or less than .06 second in V5 and V6.
• RBBB & RVH -the VAT is prolonged in
leads V1 & V2
• LBBB & LVH-the VAT is prolonged in
Leads V5 & V6
Pathophysiology of the BB and
Fascicular Blocks
• Ischemia heart disease
• Acute Mi
• Idiopathic degenerative disease of Conduction
system
• Cardiomyopathy
• LVH
• Aberrant ventricular conduction
• Miscellaneous causes such as
– Acute or chronic HF, PE, AoValve Disease, Tumors,
Trauma, Potassium overdose
Right Bundle Branch Block
• The electrical impulses are prevented from
entering the RV directly because of disruption of
conduction system.
• RBBB present with intact viable IVS
• RBBB present without intact viable IVS
• ECG characteristics of the two RBBB’s differ
significantly
• Compare Leads 1 & V1, V6
RBBB
• Impulses travel down the LBB in to the IS &
LV-(Normal)
• IS to right to enter the RV after a short delay
• LV depolarize in normal way: first the septum
from left to right
• Then the LV from right to left
• LV depolarization
• RV depolarizes in a normal direction
• Delay results in a wide bizarre shape/appearance
• .12 seconds or greater (complete)
• .10 and .11 seconds (incomplete)