ANALYSIS OF ATRIAL SENSED FAR-FIELD VENTRICULAR SIGNALS - A REASSESSMENT

Accurate detection of the spontaneous far-field ventricular signal may be used to determine the ventricular activation, and hence, the inter val from atrial stimulus to the ventricular R wave (AR interval) using a standard atrial pacing lead. This can be useful in developing a phy siological atrial rate responsive (AAIR) pace-maker and in further imp roving DDD(R) pacing algorithms. In order to better characterize the a trial sensed far-field ventricular signal, 200 consecutive patients un dergoing pacemaker implantation were studied. The amplitude of the far -field ventricular signal was significantly smaller than that of the a trial deflection. In all recordings, the slew rate oft he atrial defle ction was larger than that of the far-field ventricular signal. Subdiv ision of the recordings by electrode position, pocket location, or QRS duration on the surface ECG resulted in significantly different signa l characteristics. The amplitude and slew rate of the far-field ventri cular signal were significantly smaller in bipolar versus unipolar sen sing. Atrial sensed far-field ventricular recordings could also be obt ained in the case of ventricular pacing. Our results indicate that acc urate sensing of the far-field ventricular signal from an atrial pacin g lead is conceivable in most patients. The different signal character istics in relation to parameters, such as electrode position, sensing mode, and pocket location, may be useful in determining the optimal co nditions for signal sensing.