EP intervals break conduction into anatomical segments. They are useful because a delay in one interval may point to a different level of the conduction system than a delay in another.
AH and HV
AH intervalMeasured from atrial activation on the His recording to His-bundle activation. It broadly reflects conduction through the AV nodal region.
HV intervalMeasured from His-bundle activation to ventricular activation and reflects His-Purkinje conduction.
Measurement principles
Interval interpretation depends on stable recordings, clear component identification, consistent measurement technique, rhythm, medications and patient context. The educational goal is to know what anatomical segment each interval represents before memorizing normal ranges.
Think anatomically
If an interval changes, ask which part of the conduction system sits between its two endpoints.
Learning objectives
LocateKnow which anatomical conduction segment AH and HV represent.
Measure thoughtfullyRecognize that clear signal identification matters before interval measurement.
Interpret in contextAvoid using an interval value without rhythm, medication and recording context.
Interval checkpoint
Question 1
Which interval best reflects conduction from His-bundle activation to ventricular activation?
Question 2
What is the safest first response when you are unsure whether a small deflection is truly a His potential?
Trusted resources
Heart Rhythm Society — EP Lab Standards Laboratory processes, protocols, equipment, personnel, safety and quality. Open HRS resource →
ESC/EHRA — Heart Rhythm learning references Recommended reading and competency topics for invasive electrophysiology. Open ESC resource →
Educational scope: This lesson explains foundational concepts. It does not teach independent performance or interpretation of invasive EP procedures. Follow institutional training, current professional guidance, and manufacturer instructions.