Etymology: L, intervallum, space between ramparts
the time between an atrial polarization and the next ventricular polarization. In a surface electrocardiogram, the A-V interval is the time between the beginning of the P wave and the beginning of the QRS complex. A normal interval is less than 200 msec. In His bundle electrograms (HBEs), the A-V interval is the time between the A wave and the V deflection. The A wave is the first deflection on the HBE and represents low right atrial activation. The V deflection is the last deflection on the HBE and represents ventricular activation; it is concurrent with the QRS complex on a surface electrocardiogram. Prolongation of this interval is known as first-degree heart block.