Clinical validation of new pacing-sensing configurations for atrial automatic capture verification in pacemakers

Atrial Automatic Pacing Capture Verification. Introduction: This study eval uated an atrial automatic capture verification scheme based on atrial evoke d response (AER). Atrial pacing was between At,p and Can (A(tip)-Can) using different coupling capacitances (CCs). Independent pairs of sensing electr odes between A(ring) and V-tip (A(ring)-V-tip) or between A(ring) and a sep arate indifferent electrode (A(ring)-Indiff) were used to reduce pacing-ind uced afterpotentials. Methods and Results: A custom-made external pacing system was used to perfo rm automatic step-up and step-down pacing (0.1 to 7.1 V at 0.5 msec, step s ize of 0.1 V) using different CCs (2 or 15 muF). Intracardiac signals from A(ring)-Indiff and A(ring)-V-tip were independently recorded and analyzed b oth in real time and off-line to detect AER. Every paced beat also was visu ally inspected and compared with surface ECG to verify the captures. With t he intracardiac signals properly filtered, AER detection was based on the s ignal within a window of 12 to 65 msec after the stimulus. Data from 27 pat ients (4 chronic and 23 acute implantations; age 65.6 +/- 13.9 years) were analyzed. Bipolar atrial lead measurements using a standard pacing system a nalyzer were as follows (mean +/- SD): impedance 695 +/- 227 Omega, P wave amplitude 4.2 +/-2.3 mV, slew rate 1.1 +/-0.9 V/sec, and pacing threshold a t 0.5 msec 1.0 +/-0.5 V. The results with CC = 2 muF showed that of 9,500 a trial paced beats, correct capture verification rates were 99.8% (A(ring)-I ndiff) and 99.4% (A(ring)-V-tip)- Similar results were achieved with CC = 1 5 muF (99.7% and 99.5%, respectively). Conclusion: AER can be reliably detected using independent pacing (A(tip)-C an) and sensing (A(ring)-V-tip or A(ring)-Indiff) electrodes. Therefore, at rial automatic capture verification by AER detection is feasible.