Sensing of concealed ventricular extrasystoles by pacemakers. Fifty years later.

Whether a pacemaker can sense concealed ventricular extrasystoles still remains debatable since its occurrence was first proposed in 1972. It must remain a diagnosis of exclusion if it really exists. Isoelectric complexes and all the causes of oversensing especially discrete false signals generated by a defective pacemaker lead must be excluded before concealed ventricular extrasystoles can be postulated.