LECTURES:
1. Intrinsicoid Deflection
2. Full ECG Course
3. The EKG Guy Lectures

Intrinsicoid deflection: time between QRS complex onset & R wave peak (in leads that begin with R wave & have no Q wave)

• Cardiac event: impulse transmission from Purkinje network in endocardium to epicardium surface directly under electrode

Intrinsicoid deflection duration:

• Right-precordial leads (V1-V2): <0.035 s (35 ms)
• Left-precordial leads (V5-V6): <0.045 s (45 ms)
• Note: shorter in right-precordial leads due to thinner right ventricle (vs. left ventricle)