Automatic Capture Verification Research Articles

Predictors of successful atrial and ventricular auto capture pacemaker algorithm post implantation: single-centre experience

Aim The aim of the present study was to assess the possible predictors of successful threshold optimization from a second-generation device (Evia DR-T Biotronik), with automatic atrial and ventricular capture management post implantation.Background It is mandatory in patients receiving permanent pacemakers to determine the pacing threshold at each follow-up visit. To facilitate pacing threshold measurements, complete automatic pacemaker tests are being developed. A new application of pacemaker algorithm for automatic capture verification is to detect the presence of the evoked response signal after the pacing impulse in the immediate post-implant period. The Evia DR-T (Biotronik, Berlin, Germany) is a device that utilizes this algorithm.Methods and result This was a retrospective single-centre study of 112 patients who received a dual-chamber Evia DR-T Biotronik (Biotronik, Berlin, Germany) pacemaker. Pacemaker interrogation was performed at the time of implantation and one day post implantation to evaluate the success of the automatic algorithm program, focusing on atrial and ventricular auto capture and lead pacing polarity. The sensing, atrial and ventricular threshold, impedance and indication of implantation were analysed as possible predictors.Conclusion In conclusion, automatic programming of the pacing threshold measurements using the Biotronik post-implant algorithm was successfully predicted from the sensing values and the manual threshold during lead implantation. Therefore, fewer requirements are necessary for post-implant auto program control than for presently available systems. Such pacemaker functions may reduce the time taken for device interrogation and patient discomfort during pacemaker implantation and hospitalization.

Biventricular capture verification by means of morphological analysis of intracardiac electrogram†

The aim of this study is to develop a new feature for automatic biventricular capture verification in cardiac resynchronization therapy (CRT) devices, by means of morphological analysis of the intracardiac electrogram (IEGM). The algorithm performs capture classification based on a novel adaptive signed correlation index (ASCI), which measures morphological similarity between the post-pace IEGM and a template waveform representing captured paces. To evaluate the performance of the algorithm, CRT pacemakers were implanted in six dogs. During a mean follow-up of 23 days, 175 biventricular threshold tests were conducted with various configurations of pace/sense polarities. Biventricular IEGMs were recorded and downloaded for offline analysis. Template signals for each pace/sense configuration in each chamber were created for individual dogs during the first follow-up. Each pace was annotated for capture or non-capture by visual examination of the IEGM. A total of 9991 capture paces and 4474 non-capture paces were included for morphological analysis. The calculated ASCI values were well separated for capture and non-capture paces irrespective of right/left pacing chambers, pace/sense configurations, pacing amplitude, individual dogs, and temporal proximity of the capture templates. Overall, the classification accuracy of the algorithm remained ≥99% for any ASCI cut-off value choosing between 0.18 and 0.52. This study demonstrated the feasibility to perform automatic biventricular capture verification based on morphological analysis of the IEGM.

Muscle Noise Effects on Atrial Evoked Response Sensing: Implications on Atrial Auto-Threshold and Auto-Capture Determination

Automatic pacing capture verification algorithms that are based on detection of local evoked response signals are susceptible to interference from myopotential noise. This is especially true in the atrium where the lower signal amplitude and signal-to-noise ratio make pacing capture verification more challenging. The aim of this study is to evaluate the impact of myopotential noise induced by various maneuvers on the atrial evoked response (AER) signal. Data were collected from 18 patients (7 M/11 F, 77.6 ± 8.8 years), implanted with a dual chamber rate response (DDDR) pacemaker and acute and chronic right atrial leads and right ventricular leads, at three regular follow-up visits scheduled at 1, 3, and 6 months after pacemaker implantation or replacement procedures. During each study visit, manual atrial pacing threshold tests during unipolar pacing in the DDD mode were conducted with two evoked response sensing configurations (RA(Ring) → Ind and RA(Ring) → V(Tip) ) while patients performed six different maneuvers. Noise estimates were calculated for each maneuver. The greatest noise estimates in both sensing configurations were measured during the hand-pressing exercise (0.649 ± 0.342 mV in the RA(Ring) → Ind vector, 0.309 ± 0.223 mV in the RA(Ring) → V(Tip) vector). No significant differences in overall noise estimates were observed between the follow-up visits. Of the beats that exhibited noise estimates greater than a sensing floor of 0.3 mV, up to 22% of cardiac beats had a signal-to-noise ratio less than 2 in the RA(Ring) → Ind configuration. Results indicate that myopotential noise generated by performing maneuvers has a demonstrable impact on AER sensing. Therefore, noise mitigation processes are necessary in atrial automatic pacing capture verification algorithms based on evoked response signals to identify and appropriately manage noise.

Actual Pacemaker Longevity: The Benefit of Stimulation by Automatic Capture Verification

We evaluated the impact of an algorithm for automatic right ventricular (RV) stimulation compared to fixed-output pacing (FOP) stimulation on actual pacemaker longevity over a 9-year follow-up. Prospective observation of 300 patients implanted with VDDR/DDDR pacemakers in 1999-2000 up to October 31, 2008. Sixty-one patients were paced by Autocapture pacing (ACP), 239 were paced by FOP; they were seen twice yearly at the pacemaker clinic. Factors known to affect pacemaker longevity were collected: median heart rate, %A&V paced activity, pacing output, and impedance. Patients dead before pacemaker replacement, lost to follow-up, or who developed permanent atrial fibrillation were excluded from analysis. One hundred twenty-six of three hundred patients completed the study. Adverse clinical events due to an increased RV threshold occurred in two FOP patients compared to none among ACP. Pacemaker replacement occurred in 1/34 ACP patients versus 60/92 FOP patients (P < 0.001). ACP was the single independent predictor of pacemaker longevity at multivariable analysis (hazard ratio = 0.03, P < 0.001) either in the overall population or in the specific patients subgroups (sick sinus syndrome, atrioventricular block, and neurally mediated syncope). Automatic verification of stimulation is reliable at long term, and warrants superior safety in the event of pacing threshold changes. It allows a significant longevity increase compared to FOP stimulation that may heavily impact the patients' quality of life and the cost of pacing therapy. Moreover, it is a fundamental technology in a strategy of remote patient and device monitoring, and may enable automatic device follow-up operated by trained, nonmedical personnel.

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

This acute data collection study evaluated the performance of a right atrial (RA) automatic capture verification (ACV) algorithm based on evoked response sensing from two electrode configurations during independent unipolar pacing. RA automatic threshold tests were conducted. Evoked response signals were simultaneously recorded between the RA(Ring) electrode and an empty pacemaker housing electrode (RA(Ring)-->Can) and the electrically isolated Indifferent header electrode (RA(Ring)-->Ind). The atrial evoked response (AER) and the performance of the ACV algorithm were evaluated off-line using each sensing configuration. An accurate threshold measurement was defined as within 0.2 V of the unipolar threshold measured manually. Threshold tests were designed to fail for small AER (< 0.35 mV) or insufficient signal-to-artifact ratio (SAR < 2). Manual threshold measurements were obtained during RA unipolar and bipolar pacing and compared across device indications. Data were collected from 38 patients with RA bipolar leads from four manufacturers. AER signals were analyzed from 34 patients who were indicated for a pacemaker (five), implantable cardioverter-defibrillator (11), or cardiac resynchronization therapy pacemaker (six) or defibrillator (12). The minimum AER amplitude was larger (P < 0.0001) when recorded from RA(Ring)-->Can (1.6+/-0.9 mV) than from RA(Ring)-->Ind (1.3+/-0.8 mV). The algorithm successfully measured the pacing threshold in 96.8% and 91.0% of tests for RA(Ring)-->Can and RA(Ring)-->Ind, respectively. No statistical difference between the unipolar and bipolar pacing threshold was observed. The RA(Ring)-->Can AER sensing configuration may provide a means of implementing an independent pacing/sensing method for ACV in the RA. RA bipolar pacing therapy based on measured RA unipolar pacing thresholds may be feasible.

Effect of Atrial Lead Position on Atrial Automatic Capture Verification

Optimizing atrial automatic capture verification based on atrial-evoked response (AER) detection requires maximizing the signal artifact ratio (SAR), that is, AER to stimulation artifact (ART). This study evaluated the effect of bipolar atrial lead position on sensed AER, ART, and SAR. A custom-made external research system (INSIGNIA(AC), Boston Scientific Corp. St Paul, MN, USA) was used to perform an automatic voltage step-down atrial pacing protocol at three different right atrial lead positions (A-appendage, L-lateral wall, and S-septal wall) in each studied patient. The atrial pacing and the AER sensing configurations were independent. The pacing was unipolar in an A(tip)-Can configuration while sensing was in A(ring)-I(ndiff). Data from 16 patients (mean age 71.1 +/- 9.6 years) and six-lead models from five different manufacturers were analyzed. Study results show that with all lead types, the atrial lead placement had no significant effect on AER(min), ART(max), and SAR(min) and only one patient had an SAR that was not sufficient to support successful automatic capture verification at all tested atrial pacing sites. The atrial pacing site has minimal effect on AER sensing when using an independent pace/sense configuration. The leads placed at all tested sites were found to have the parameters sufficient to support the atrial automatic capture verification in all but one patient.

RVcoil to Can Evoked Response Comparison between ICD and CRT-D for Automatic Capture Verification

Introduction: Automatic pacing threshold (AT) testing with trending and output adjustment may simplify device follow-up and improve longevity. A right ventricular (RV) AT algorithm was developed for ICD/CRT-D. The algorithm is based on RVcoil to Can evoked response (ER) sensing and utilizes ER consistency for capture verification. The objective of this analysis was to compare ER characteristics between ICD and CRT-D systems. Methods: Patients (pts) scheduled for ICD/CRT-D implant, replacement or upgrade were enrolled.

Abstract 2514: Automatic Biventricular Capture Verification Based On Morphological Analysis of the Intracadiac Electrogram Signal

Objective: We test a new biventricular capture verification algorithm, which can be used to adjust the pacing output in right ventricle (RV) and left ventricle (LV), to ensure the safety and efficacy of the cardiac resynchronization therapy (CRT). Methods: The algorithm calculates a novel index called ASCI, which measures the morphological similarity between the intracardiac electrogram (IEGM) signal and a template waveform representing captured paces. Ventricular capture (CAP) is verified if ASCI is greater than a predefined threshold, whereas non-capture (NC) is declared otherwise. CRT pacemakers were implanted in 6 dogs. During a mean follow-up of 23 days, 175 biventricular threshold tests were conducted by running a customized program, with various combinations of pace/sense polarities. Wideband RV and LV IEGM were recorded and downloaded for off-line analysis by the algorithm. Template signals for each pace/sense configuration in each chamber were created from the average of 4 captured beats. Each pace was annotated for CAP or NC by visual examination of the IEGM and based on stored data log of the pacing parameters. Results: A total of 9991 CAP paces (5104 RV, 4887 LV) and 4474 NC paces (2136 RV, 2338 LV) were eligible for morphology analysis. In both RV and LV, the calculated ASCIs were well separated for CAP and NC paces (Figure ): 0.83 ± 0.12 (RV CAP), 0.85 ± 0.11 (LV CAP), -0.06 ± 0.13 (RV NC), -0.07 ± 0.14 (LV NC). The classification accuracy of the algorithm remained &gt;= 99% for any ASCI threshold value choosing between 0.18 and 0.52. Conclusion: This study demonstrated the feasibility to perform automatic biventricular capture verification based on morphology analysis of the IEGM.

Left ventricular pacing by automatic capture verification

To investigate the feasibility of transvenous left ventricular (LV) pacing by autocapture at long term. A reliable measurement of LV evoked response (ER) is the pivotal requirement for beat-to-beat detection of ventricular capture and automatic output adjustment. Seven patients with accepted class I indication to permanent cardiac pacing received a DDDR pacemaker with automatic output adjustment based on beat-to-beat capture verification (Insignia Ultra 1290, Guidant), whose ventricular port was connected to a LV lead placed in a branch of the coronary sinus. The device allows LV threshold trending, performing a threshold test every 21 h, and diagnoses acute and non-acute issues of ER detection during follow up. Average follow up after implantation was 34 +/- 6 months (range 28-45, median 34). Left ventricular pacing threshold showed an increase from implantation (1.2 +/- 0.4 V at 0.4 ms) that peaked at week 4 (1.6 +/- 0.7 V at 0.4 ms), and returned to baseline (1.1 +/- 0.5 at 0.4 ms) by the end of the 7th week. Autocapture performance at long term, as assessed by the trend of LV threshold and of ER diagnostic issues, did not show any pitfall. Our observations support the feasibility and safety of capture verification during LV pacing alone. A possible application of this pacing technology could be biventricular stimulation.

Improved ER Signal Quality and Capture Discrimination during Early vs. Late LV Pacing Using the Reduced Coupling Capacitor Technology with Biventricular Pacing

Introduction: Automatic Capture Verification (ACV) technology enables advancement in automated and remote patient management. The reliability of evoked response (ER) sensing via reduced output coupling capacitor technology has been clinically proven. This technology was applied to the LV and used in this study to evaluate the effect of interventricular pacing timing or LV Offset (LVO) during biventricular (BiV) pacing for a new ACV algorithm. Methods: Sinus rhythm patients (pts) indicated for CRT-D implantation were enrolled for intraoperative evaluation.

Failure of Automatic Capture Verification in an Epicardial Pacemaker System

Epicardial pacing is frequently used in pediatric patients with congenital heart disease. Automatic threshold determination has been reported to be safe in epicardial lead systems. We report a case of falsely low ventricular thresholds determined by automatic capture verification in a patient with complete loss of capture due to a lead fracture.

Clinical Performance of a Ventricular Automatic Capture Verification Algorithm

This study was conducted to evaluate the clinical performance of the ventricular automatic capture feature as implemented in the Insignia I Ultra pacemaker system (Guidant) utilizing a variety of ventricular leads. Currently, the optimal programming of the pacemaker output considers both pacemaker efficiency (prolonging battery longevity) and patient safety (adequate safety margin). The ability of a pacemaker to automatically adjust the ventricular output above the pacing threshold while maintaining the appropriate safety margin has been explored since the early 1970s and is only available today in conjunction with a specific low polarization lead system. One hundred and five patients were enrolled from 17 European centers utilizing 31 different types of ventricular leads were followed through their 3-month follow-up visit. There were no restrictions on the type of ventricular leads used. The average mean difference between the commanded autothreshold test (0.652 + 0.335 V) and the manual threshold test (0.651 + 0.335 V) was 0.001 + 0.49 (P < 0.0001). The average mean difference between the ambulatory autothreshold test (0.696 + 0.322 V) and the commanded autothreshold test (0.682 + 0.315 V) was 0.002 + 0.74 (P < 0.0001). Holter recordings confirmed that there were no loss of capture incidences without a backup pulse being delivered. In addition, the mean number of backup pulses delivered in a 24-hour period was less than 0.1% of the total number of paced beats. This study provided that the automatic capture feature while using a variety of leads accurately determines the ventricular stimulation threshold and safely delivers a backup pulse when required.

Algorithm for ventricular capture verification based on the mechanical evoked response

Automatic pacemaker capture verification is important for maintaining safety and low energy consumption in pacemaker patients. A new algorithm was developed, based on impedance measurement between pacing electrode poles, which reflects the distribution of the conducting medium between the poles and changes with effective contraction. Data acquired during pacemaker implant in 17 subjects were analysed, with intracardiac impedance recorded while pacing was performed in the ventricle at varying energies, resulting in multiple-captured and non-captured beats. The impedance signals of all captured/non-captured beats were analysed using three different algorithms, based on the morphology of the impedance signal. The algorithm decision for each beat was compared with an actual capture or non-capture, as determined from the simultaneous recording of surface ECG. Two of the three algorithms (Z1 and Zn) were based on impedance values, and one (Z'n) was based on the first derivative of the impedance. Z1 was based on a single sample, whereas Z'n and Z'n were based on several samples in each beat. The total accuracy for each was Z1: 43%, Zn: 87%, Z'n: 92%. It was concluded that impedance-based capture verification is feasible, that a multiple rather than single sample approach for signal classification is both feasible and superior, and that first derivative analysis with multiple samples (Z'n) provides the best results.

BIV capture verification utilizing RVcoil to can evoked response in CRT-D patients

Objectives: Automatic capture verification may be used to ensure adequate pacing output level and consistent resynchronization therapy in CRT patients. During CRT threshold testing, it is difficult to assess LV capture without multiple surface ECGs. Previously, a Capture Detection Algorithm (CDA) for ICD RV threshold testing was developed using RVcoil to Can evoked response morphology, with accurate discrimination ability. In this study, we demonstrated the feasibility of an extended CDA for CRT-D device to detect capture in a bi-ventricular setting (BiV, RV only and LV only capture).

Evaluation of Fusion Beat Detection with a New Ventricular Automatic Capture Algorithm in ICDs

This study evaluated a newly developed automatic capture verification scheme for implantable cardioverter defibrillators (ICDs) regarding discrimination of capture, fusion, and noncapture beats, with an emphasis on fusion detection. The algorithm uses evoked response detection based on a sensing vector from right ventricular shocking coil to Can. Patients undergoing ICD implant or replacement were enrolled in this study. An external system was used for pacing and data acquisition. To provoke ventricular fusion beats, VVI patients were paced close to the rate of their intrinsic rhythm and DDD patients were paced close at their intrinsic PR interval. Surface ECG and wideband filtered intracardiac electrograms were recorded for off-line analysis. Each paced beat was independently classified visually by surface ECG and by the automatic detection algorithm. The algorithm performance was then evaluated by comparing the classification results. Twenty-seven patients (22 males, 5 females; 63.8 +/- 12.5 years) were analyzed. Device and lead demographics were: 18 DDD/9 VVI; 16 dedicated bipolar, 11 integrated bipolar leads; 18 acute, 9 chronic (3.7 +/- 2.0 years) leads. In total, 2064 beats were analyzed, including 1,477 fusion beats and 587 capture beats. Fusion detection sensitivity and specificity were 99.5% and 99.0%, respectively. Seven true-fusion beats (0.5%) were classified as capture and 6 capture beats (1.0%) were identified as fusions. Capture or fusion beats were never detected as non-capture beats. It is concluded that the algorithm was effective in detecting fusion beats. It could potentially be used in ICD applications that need accurate fusion detection.

Accelerometer-based heart sound detection for autocapture

An implantable cardiac rhythm management device capable of automatically detecting intrinsic and evoked response of a patient's heart. The device operates in an automatic capture verification mode, wherein a global accelerometer signal is utilized to identify heart sounds (S1 and S2) of the patient's heart. The presence or absence of one or more of the heart sounds S1 and S2 in the accelerometer signal indicates whether a stimulation pulse evokes a response by the patient's heart. The device may automatically adjust the stimulation output in accordance with a step down stimulation protocol, wherein the presence of a predetermined heart sound indicates capture. Also, the device may suspend the automatic capture verification sequence if the patient's physical activity level exceeds a predetermined threshold.

P-368 Clinical validation of a new automatic atrial capture verification algorithm

P-368 Clinical validation of a new automatic atrial capture verification algorithm

P-368 Clinical validation of a new automatic atrial capture verification algorithm

P-368 Clinical validation of a new automatic atrial capture verification algorithm

P378 Clinical validation of a new automatic atrial capture verification algorithm

P378 Clinical validation of a new automatic atrial capture verification algorithm

Automatic capture verification in ICD lead systems using intracardiac ventricular evoked response and reduced coupling capacitance.

Intracardiac ventricular evoked-response (ER) signals detected by implanted cardioverter defibrillator (ICD) lead systems were investigated for automatic capture verification (AC). ER signals were evaluated with an external pacing system equipped with a reduced coupling capacitance (CC=2.2 microF) in the pacing output circuit during ventricular step-down threshold testing at 0.4 ms pulse duration. Real-time pacing markers, surface ECG and intracardiac electrograms pre- and post-filtering were digitally recorded. Twenty consecutive patients, age 61+/-12 years, with leads from two different manufacturers were tested - 10 were implanted with acute leads (AL) and 10 with chronic leads (CL). The analysis was based on the ER amplitude during capture and on the ER-to-afterpotential ratio (SAR), with SAR>2 as the criterion for successful capture detection. ER amplitudes (median and range) were 8.1 mV (2.1-19.5 mV) for AL and 8.3 mV (3.7-14.2 mV) for CL. SAR values (median and range) were 48.0 (2.5-682.6) for AL and 13.2 (6.3-35.9) for CL, indicating that AC could successfully be applied in all patients. Reducing the pacing CC allows adequate ER detection for automatic capture verification on non-selected ICD lead systems. The effect of high-voltage shock treatment on ER signal detection requires further investigation.