[Peculiarities in the follow up of resynchronization therapy]

While resynchronization therapy (CRT) is based on conventional pacemaker- and ICD technology, its main intention is to minimize inter- and intraventricular asynergy and to establish optimal AV timing if sinus rhythm is preserved. The focus of this contribution is a series of conditions which jeopardize the therapeutic goal of CRT and should be recognized and hopefully corrected during follow up of CRT systems. These scenarios include uncertainties about left ventricular capture, double sensing in the ventricles, inhibition of the ventricular output (and loss of resynchronization), atrial and ventricular tachycardia and rate adaptation. Technical issues of following rhythm management devices are only discussed in the context of CRT requirements.