AMPLITUDE AND DIRECTION OF ATRIAL DEPOLARIZATION USING A MULTIPOLAR FLOATING CATHETER - PRINCIPLES FOR A SINGLE LEAD VDD PACING

VDD stimulation using a single catheter for atrial sensing and ventricular sensing and pacing has become a reality. In order to compare the quality of the cavitary atrial electrogram (AEG) and to determine the intraatrial P wave direction and conduction time (CT), we compared, in an acute study, three different types of atrial electrode systems using four different leads, in 53 patients in sinus rhythm. The three electrode systems were: (1) one experimental system with quadripolar orthogonal electrodes using the Goldreyer concept; (2) one experimental system with quadripolar whole ring electrodes; (3) two systems with diagonally oriented half-ring electrodes, one experimental quadripolar and one bipolar CCS commercial (Polysafe A-Track lead). For the experimental systems, the four electrodes forming two independent bipolar pairs were situated on the intraatrial floating portion of a single lead and one supplemental electrode was distally positioned in the right ventricular apex. Bipolar AEGs were recorded at the high and at the low levels of the right atrium. For the CCS lead, the single bipolar AEG was recorded at the high level of the right atrium only. The highest AEG amplitude and the highest values for ventricular far-field rejection were provided by both diagonally oriented half-ring electrodes at the high atrial level and by the whole ring electrodes at the low atrial level. For both atrial levels, the orthogonal electrode system provided the smallest AEG amplitudes, the highest ventricular electrogram amplitudes, and therefore, the smallest values for ventricular far-field rejection. With the three quadripolar experimental systems, in sinus rhythm, the direction of the intraatrial depolarization was high-low in 46 patients (87%) and low-high in 3 patients (6%), with a mean CT of 28.9 ms and 23.3 ms, respectively; high and low AEGs were recorded simultaneously in 4 patients (7%). During ventricular pacing, retrograde (V-A) conduction was present in 35 patients. The intraatrial depolarization was low-high in 25 of them (71%) and high-low in 7 patients (20%), with a mean CT of 32.6 ms and 23.4 ms, respectively; high and low AEGs were recorded simultaneously in 3 patients (9%), but with different morphology and polarity than in sinus rhythm. In conclusion, the floating multipolar whole ring and half-ring electrodes are capable of recording high quality AEG and, because of their multipolarity, they are capable of providing information about atrial activation sequences. These features may theoretically be useful for a monolead VDD pacing system with diagnostic features.