Understanding capture detection

Abstract

Automatic capture detection systems are currently available in several cardiac pacing devices. All current systems use low-polarization electrodes and no beat to beat detection system is available for all types of electrodes. In addition the success ratio for currently available systems is not always 100%. Failure to detect capture reliably is often related to the behaviour of the electrode-tissue interface under different circumstances. Pacemaker electrodes can be considered electrochemical cells with complicated characteristics depending on time, temperature and electrical charge. This electrochemical cell is disturbed when a charge is transferred across the electrode-tissue interface during pacing. Several measures can be taken in order to minimise this disturbance or pace polarization artefact (PPA) including the use of high active surface area electrodes and application of tri-phasic pacing pulses. Another factor influencing detection of evoked potentials is the input circuit of the pacemaker affecting the PPA and the evoked response. Positive PPAs can be falsely interpreted as evoked potentials due to the undershoot of the second order filters applied in modern cardiac pacemakers. This paper explains the behaviour of the interface between the electrode and the cardiac tissue in combination with the pacemaker output circuits and input amplifiers under different circumstances.

Performance of a Ventricular Automatic‐Capture Algorithm in a Wide Clinical Setting

“…For many years, prolonging PM life without compromising patient safety has been a primary goal of the application of AC features. A good device‐based capture‐detection system that is able to continuously adjust the pacing voltage should be based on the reliable beat‐by‐beat detection of the ER which follows each PM stimulus; this is done by minimizing pacing artifacts due to electrode polarization, pacing pulse, and electrode‐tissue interface 4 . Reliable detection of ER should also be unaffected by the amount of current delivered at the lead‐tissue interface and, therefore, by the output pacing voltage.…”

“…Currently, several different ventricular automatic capture (AC) algorithms, which automatically adjust pacing voltage output according to threshold and deliver high‐energy backup pacing in the event of loss of capture (LOC), are commercially available for VVI/R and DDD/R PMs 3 . AC algorithms are based on reliable detection of the ventricular evoked response (ER), which requires a high signal/pacing artifact ratio 4 . This means that either the amplitude or the duration of the postpacing artifact needs to be reduced in order to prevent the pacing artifact from masking the ER.…”

Performance Evaluation of a Right Atrial Automatic Capture Verification Algorithm using Two Different Sensing Configurations

“…In recent decades, various automatic capture verification (ACV) algorithms have been developed to automatically measure the pacing threshold and responsively adjust the pacing output in implantable devices to prevent loss of therapy. Such features are believed to improve patient safety and battery longevity as well as to significantly impact current in‐clinic procedures and future remote device follow‐up 6–13 …”

Clinical Evaluation of Two Different Evoked Response Sensing Methods for Automatic Capture Detection in the Left Ventricle

“…Automatic capture verification (ACV) refers to the ability of a cardiac pacing device to determine if a delivered pacing stimulus results in stimulation of the surrounding myocardium. ACV is a device feature with implications for safety, ease of use, and battery longevity 5–7 . Evaluation of the cardiac depolarization or evoked response (ER) following the pacing pulse is a common method for implementing ACV features 8–13 .…”

“…ACV is a device feature with implications for safety, ease of use, and battery longevity. [5][6][7] Evaluation of the cardiac depolarization or evoked response (ER) following the pacing pulse is a common method for implementing ACV features. [8][9][10][11][12][13] This approach is challenged by the ability to discriminate between the myocardial ER signal and the pace-induced residual voltage or pacing artifact (ART) remaining on the lead/tissue interface.…”