Electrical parameters with His-bundle pacing: Considerations for automated programming

BACKGROUND Programming of His-bundle pacing may be challenging because current implantable pulse generators are not specifically designed for this pacing modality. OBJECTIVE The purpose of this study was to evaluate electrical parameters in order to propose preset programming options with different configurations. METHODS Data were collected from 50 patients with His pacing leads connected to various ports (atrial, right ventricular, or left ventricular) of pacemakers and defibrillators during a detailed device interrogation, which included capture thresholds with various pacing vectors, measurement of timing intervals, and performance of automatic threshold algorithms. RESULTS His-bundle pacing thresholds were significantly lower during unipolar pacing compared to bipolar and extended bipolar polarities. However, current drain was offset due to lower impedance. The His pace-right ventricular sensed intervals were measured at 40-150 ms (mean 85 +/- 25 ms), with the longest delays in patients with uncorrected right bundle branch block and selective His capture. This has implications for ventricular safety pacing windows (which were inactivated without evidence of crosstalk) and delays to minimize unnecessary ventricular backup pacing (which was also affected by refractory periods). The measured intervals also impacted the performance of automatic threshold algorithms, which performed differently depending on which port the His lead was connected to and did not distinguish between His and myocardial capture. CONCLUSION Our report provides data that could serve to configure automated programming settings to simplify management of His-bundle pacing.