Reduction of pacing output coupling capacitance for sensing the evoked response

Area of Science:

• Biomedical Engineering
• Cardiovascular Technology
• Implantable Electronic Devices

Background:

• Intracardiac evoked response (ER) sensing is crucial for pacemaker capture verification.
• Large pacing afterpotentials interfere with reliable ER detection.
• Existing solutions include triphasic pulses and low polarizing electrodes.

Purpose of the Study:

• To investigate the impact of reduced coupling capacitance (CC) on afterpotential magnitude.
• To assess the efficacy of automated ventricular evoked response detection with reduced CC.
• To evaluate a new capture verification scheme using a 2.2 microF CC and specific timing settings.

Main Methods:

• A clinical study involving 54 patients with ventricular pacing leads.
• Testing of a 2.2 microF CC with four blanking/recharge time settings.
• Utilized an automatic step-down threshold algorithm and a pacing system analyzer (PSA).
• Evaluated unipolar (UP) and bipolar (BP) configurations with wide-band (WB) and narrow-band (NB) filters.

Main Results:

• The new capture verification scheme (2.2 microF CC, 10/12 ms timing) succeeded in 96% of patients (52/54).
• Wide-band (6-250 Hz) sensing in unipolar configuration showed significantly higher signal-to-artifact ratios (SAR) (P < 0.01).
• No restrictions on pacing lead models or pacing/sensing configurations were observed.

Conclusions:

• Reducing coupling capacitance is effective in minimizing afterpotentials for improved ER sensing.
• A dedicated unipolar ER sensing configuration with a small output capacitor and wide-band filter enables robust automatic capture verification.
• This approach offers a versatile solution for automatic capture verification in pacemakers.