Abstract
DDD pacing has been used to maintain AV synchrony and to improve hemodynamics. However, continuous effective atrialsensing unnecessary condition for proper DDD pacing. For this reason, it is wellknown that the possibility ofrapid ventricularpacing exists during atrialtachyarrhythmia (AA). Thirty-one patients (pts) with a ODD or DDDRpacemaker —META DOOR 1250 (n=7), META DDDR 1254 (n=5), Chorus I (n=2), Chorus II (n=5), Relay (n=5), Cosmos (n=7), were studied retrospectively. Inappropriate high rate tracking was observed in 4/7 pts with a conventional DDD pacemaker (Cosmos). Other pacemakers designed to prevent rapid ventricular tracking of AA effectively reduced and regularized the ventricular responses during AA. Despite the successful controlofhigh rate trackmg, sinus tachycardia caused an undesirable mode switch to occur in some pts and every newalgorithm had its own limits. These results suggest that the conventional DDD pacemaker is a poor choice for ptswith AA and that newalgorithms (automatic mode switching) may be an acceptable mode to controlthe ventricular rate in pts with AA and those who require duatchamber pacemaker.
