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Biomedical subjects

S Furman

Publications and source records attributed to S Furman.

353 records · Page 20Linked to original sources
PubMed1965

Cardiac pacing.

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Humans↗
PubMedDate not supplied

Unipolar and bipolar right atrial appendage electrodes: comparison of sensing characteristics.

To optimize atrial sensing and reject far-field signals (i.e., ventricular potentials seen in the atrium), the atrial amplitudes of electrograms (EGMs) should be as high as possible and the ventricular amplitudes as low as possible. To compare clinical sensing results obtained with unipolar and bipolar electrodes, endocardial EGMs were recorded on a high-speed multichannel recorder with a paper speed of 200 mm/second and frequency cutoffs at 0.1 and 2,000 Hz. Forty acute unipolar and 18 acute bipolar electrodes (in different patients), three matched pairs of unipolar and bipolar electrodes, and seven coronary sinus electrodes were measured. Unipolar and bipolar right atrial appendage (RAA) electrode EGMs were compared for 1) amplitude of EGM, 2) slew rate (dv/dt); and 3) amplitude of the ventricular EGM as measured through the RAA electrode. Unipolar RAA EGMs were compared with unipolar coronary sinus EGMs. Three bipolar leads were measured as unipolar and bipolar simultaneously. Bipolar atrial EGMs had equal amplitudes (unipolar, 4.2 +/- 2.1 mV, versus bipolar, 5.9 +/- 2.5; NS), higher slew rates (unipolar, 2.6 +/- 1.6 V/second, versus bipolar, 4.4 +/- 2.1; P less than 0.005), and lower ventricular (far-field) amplitudes (unipolar, 1.1 +/- 1.1 mV, versus bipolar, 0.7 +/- 0.6; P less than 0.02) when compared with unipolar RAA electrodes. This observation was confirmed in the measurement of the matched pairs atrial/ventricular amplitude ratio (unipolar, 4.7 +/- 2.2, versus bipolar, 8.7 +/- 2.0; P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Function↗
PubMedDate not supplied

Endocardial electrograms and pacemaker sensing.

Endocardial electrograms in 77 acute cases (at time of pacemaker implant) and 56 chronic cases (at time of pulse generator replacement, with electrodes in service for at least 6 months) were recorded. The peak-to-peak voltage and rate of rise, or slew rate, were compared acutely and chronically. Both parameters must simultaneously exceed given thresholds to trigger the sensing circuits of implantable pacemakers. The average chronic slew rate was half the average acute value. The maximum slew rate and voltage swing occur during the intrinsic deflection as a virtually straight line segment of the electrogram. The findings are consistent with the predictions of a mathematical model for genesis of the electrogram, and also with a model for explaining acute-to-chronic changes in stimulation current thresholds.

Electrocardiography↗