A delta wave is the result of concealed retrograde conduction from the ventricle during normal sinus rhythm. True or False?

• A. True
• B. False. It is considered manifest
• C. False. It is considered concealed
• D. Not enough information

Answer: (B)

Delta waves come from pre-excitation where an accessory pathway conducts from atria to ventricles during normal sinus rhythm, causing early ventricular activation. This antegrade conduction through the pathway shortens the PR interval and creates the characteristic slurred upstroke of the QRS complex. Because this early ventricular activation is visible on the surface ECG, the pre-excitation is manifest, not hidden. Concealed conduction refers to retrograde conduction (ventricle to atrium) that does not produce a delta wave during sinus rhythm and is not the mechanism behind a delta wave. So the statement is false—the delta wave represents manifest pre-excitation, not concealed retrograde conduction.