Impulse wavelength is the product of the conduction velocity and the effective refractory period.

This is termed the effective refractory period (ERP) of the tissue.

Effective refractory period (Medicine- Cardiac electrophysiology)

Bretylium prolongs the action potential duration (APD) and the effective refractory period (ERP; the time after an action potential when a cell cannot be depolarized) without affecting conduction.

This atrial-selective activity of AZD1305 prolongs effective refractory period (ERF) and induces post-repolarization refractoriness (PRR) in atrial myocytes, which aids in suppressing atrial fibrillation.

High risk features that may be present during PES include an effective refractory period of the accessory pathway less than 270 ms, multiple pathways, septal location of pathway, and inducibility of supraventricular tachycardia.

Reduction of K+ current by 69% led to increased AP duration and increased effective refractory periods, thus shown to suppress pacemaker potential of the SA node and return patients to a normal heart rhythm.