Guido Gaggini

Programming Optimal Atrioventricular Delay in Dual Chamber Pacing Using Peak Endocardial Acceleration: Comparison with a Standard Echocardiographic Procedure

DUPUIS, J.‐M., et al .: Programming Optimal Atrioventricular Delay in Dual Chamber Pacing Using Peak Endocardial Acceleration: Comparison with a Standard Echocardiographic Procedure. Optimization of programmed atrioventricular delay in dual chamber pacing is essential to the hemodynamic efficiency of the heart. Automatic AV delay optimization in an implanted pacemaker is highly desirable. Variations of peak endocardial acceleration (PEA) with AV delay at rest correlate well with echocardiography derived observations, particularly with end‐diastolic filling and mitral valve closure timings. This suggests the possibility of devising a procedure for the automatic determination of the optimal AV delay. The aim of this study was to compare a proposed algorithm for optimal AV delay determination with an accepted echocardiographic method. Fifteen patients with high degree AV block received BEST‐Living pacing systems. Automatic AV delay scans were performed at rest (60–300 ms in 20‐ms steps with 60 beats per step) in DDD at 90 ppm, while simultaneously recording cycle‐by‐cycle PEA values, which were averaged for each AV delay to obtain a PEA versus AV delay curve. Nonlinear regression analysis based on a Boltzmann sigmoid curve was performed, and the optimal AV delay (OAVD) was chosen as the sigmoid inflection point of the regression curve. The OAVD was also evaluated for each patient using the Ritter echocardiographic method. Good sigmoid fit was obtained in 13 of 15 patients. The mean OAVD obtained by the PEA sigmoid algorithm was 146.9 ± 32.1  ms , and the corresponding result obtained by echocardiography was 156.4 ± 34.3  ms (range 31.8–39.7 ms). Correlation analysis yielded r = 0.79, P = 0.0012. In conclusion, OAVD estimates obtained by PEA analysis during automatic AV delay scanning are consistent with those obtained by echocardiography. The proposed algorithm can be used for automatic OAVD determination in an implanted pacemaker pulse generator. (PACE 2003; 26:[Pt. II]:210–213)

Hemodynamic assessment of right, left, and biventricular pacing by peak endocardial acceleration and echocardiography in patients with end-stage heart failure.

Multisite ventricular pacing acutely improves the hemodynamic status in heart failure, though longer‐term observations require invasive procedures. The hemodynamics of multisite ventricular pacing were assessed by echocardiography and peak endocardial acceleration (PEA) measured by a pacemaker sensor. PEA variations are highly correlated with those of dP/dt. Thirteen end‐stage heart failure patients (left ventricular ejection fraction < 0.30) with a QRS ≤140 ms received a DDD PEA sensor‐driven pacemaker allowing right (RV), left (LV) and biventricular (BV) pacing. Ten days after implantation, standard echocardiographic parameters and variations in PEA were measured after 20 minutes at each pacing mode. The aortic systolic preejection time interval was statistically comparable between RV and LV pacing (218 ± 24 vs 219 ± 34 ms; P = NS), and significantly shorter with BV pacing (198 ± 27 ms; P = 0.013). Aortic ejection duration was nonsignificantly shorter during BV pacing than during LV pacing (‐.061, P = 0.09). The aortic velocity time integer increased during LV pacing versus RV pacing (+21 %, P < 0.05) and during BV pacing versus RV pacing (+37%, P = 0.05). As a result, the values of the PEA variations over a 15‐minute period were significantly greater during LV pacing and BV pacing versus RV pacing (+43%, P < 0.05, and +38%, P = 0.05, respectively) and were statistically comparable between BV pacing and LV pacing (+5.9% for LV pacing, P = NS). During various ventricular pacing configurations, PEA measurements were consistent with echocardiographic data, showing comparable hemodynamic effects of BV and LV pacing. The PEA sensor is a promising tool for long‐term hemodynamic monitoring and serial evaluation of the effects of multisite ventricular pacing in heart failure patients.

Atrioventricular interval optimization in the right atrial appendage and interatrial septum pacing: a comparison between echo and peak endocardial acceleration measurements.

PADELETTI, et al.: Atrioventricular Interval Optimization in the Right Atrial Appendage and Interatrial Septum Pacing: A Comparison Between ECHC and Peak Endocardial Acceleration. Interatrial septum pacing (IASP) reduces interatrial conduction time and consequently may interfere with atrioventricular delay (AVD) optimization. We studied 14 patients with an implanted BEST Living system device able to measure peak endocardial acceleration (PEA) signal. The aims of our study were to compare the (1) optimal AVD (OAVD) in right atrial appendage pacing (RAAP) and IASP, and (2) OAVD derived by the PEA signal versus OAVD derived by Echo/Doppler evaluation of the left ventricular filling time (LVFT) and cardiac output (CO). Measurements were performed in DDD VDD modes Eight patients (group A) had RAAP and six patients (group B) had IASP. In group A, OAVD measured by LVFT, CO, and PEA was 185 ± 23 ms, 177 ± 19 ms, and 192 ± 23 ms in DDD and 147 ± 19 ms, 135 ± 27 ms, and 146 ± 20 ms in VDD, respectively. OAVD measured by LVFT, CO, and PEA was significantly longer in DDD mode than in VDD (P < 0.01, P < 0.01, P < 0.001). In group B, OAVD measured by LVFT, CO, and PEA was 116 ± 19 ms, 113 ± 10 ms, and 130 ± 30ms in DDD and 106 ± 16 ms, 96 ± 15 ms, and 108 ± 26 ms in VDD, respectively. No statistical differences were observed between DDD and VDD. Significant correlations between OAVDs PEA derived and OAVDs LVFT and CO derived were observed (r = 0.71, r = 0.69, respectively). When new techniques of atrial stimulation, as IASP, are used an OAVD shorter and similar in VDD and DDD has to be considered. The BEST Living system could provide a valid method to ensure, in every moment, the exact required OAVD to maximize atrial contribution to CO.

Peak Endocardial Acceleration Reflects Heart Contractility Also in Atrial Fibrillation

Previous studies demonstrated that peak endocardial acceleration (PEA) in sinus rhythm is related to LV dP/dtmax. Until now, PEA was never evaluated during R‐R interval variations in AF. The aim of this study was to establish the behavior of PEA in AF and the relationship of PEA versus LV dP/dtmax. Six sheep (65 ± 6 kg) were instrumented with a LV Millar catheter and with an accelerometer lead. AF was induced and PEA, LV dP/dtmax, and ECG were monitored. AF persisted for 5 ± 1.3 minutes. From sinus rhythm to AF, the heart rate went from 92 ± 3 to 130 ± 35 beats/mm (P < 0.05), LV dP/dtmax from 684 ± 18 to 956 ± 344 mmHg/s (P = NS) and PEA from 0.82 ± 0.06 to 0.94 ± 0.33 g (P = NS). The correlation between PEA and LV dP/dtmax was significative in sinus rhythm (r = 0.7, P < 0.05) and in AF (r = 0.8, P < 0.05). A positive relationship was found between the preceding interval and PEA (r = 0.4 ± 0,07, P < 0.05) and LV dP/dtmax (r = 0.61 ± 0.08, P < 0.05), while a negative one was found between the prepreceding interval and both PEA (r =− 0.39 ± O.11.P < 0.05) and LV dP/dtmax (r =− 0.64 ± 0.05, P < 0.05). At the onset of AF, LV dP/dtmax and PEA showed similar changes: beat‐to‐beat correlation between PEA and LV dP/dtmax was high. As for LV dP/dtmax, PEA is positively related to the preceding interval and negatively related to the prepreceding interval. These data confirm that PEA reflects heart contractility also during AF and hold promise for the use of this sensor in therapeutic implantable devices.

Relationship between Amplitude and Timing of Heart Sounds and Endocardial Acceleration

Objective: To study the correlation between heart sounds and peak endocardial acceleration (PEA) amplitudes and timings, by modulation of paced atrioventricular (AV) delay in recipients of dual chamber pacemakers.

Mixed microprocessor-random logic approach for innovative pacing systems.

Modern pacing systems are becoming more and more sophisticated. Conversion of the information supplied by a sensor into suitable parameters for a rate controlling algorithm and the management of complex timing are common tasks for an integrated circuit (IC) in cardiac pacing. An effective solution consists of using a microprocessor to implement algorithms and pacing modes in a flexible way. The key point of using the same hardware resources for different tasks on a time sharing basis allows the design of a less complex 1C when compared to a random logic structure with the same performances. The major design problems in a full microprocessor solution are its relatively low operating speed due to the low frequency clock necessary for low current drain, and the sequential structure of the machine itself. This can lead to unacceptable timing inaccuracy in all situations requiring the management of complex decision trees. In order to take full benefit from the advantages of a microprocessor structure without these drawbacks, a mixed microprocessor‐random logic approach has been investigated. This architecture uses a microprocessor core to perform all high level nonreal‐time operations (setup of the pacing cycle, data reduction and processing, data integrity checks) while a set of random logic peripherals is used for all critical timing aspects.

CRT46: BEAT-TO-BEAT EVALUATION OF SYSTOLIC TIME INTERVALS BY ANALYSIS OF ENDOCARDIAL ACCELERATION

Background Echo evaluation of cardiac timings is a widely recognized method for assessing CRT patients. Endocardial Acceleration (EA), in its systolic (PEA I) and diastolic (PEA II) components, allows estimation of cardiac timings. Aim: to evaluate the correlation between Echo and EA measurements of Aortic Pre-ejection Interval (AoPEI) and Ejection Time (ET). Methods Fifteen CRT patients (10M, age 71.2±7.0 y) (NYHA III-IV, EF 25.6±7.6%) were implanted with Sorin Biomedica Living CHF Pacemakers, able to record and transmit EA signal via telemetry. Several pacing configurations were evaluated for each patient (R, L, Biventricular at different VV and AV delays). EA and Intracardiac EGM were recorded via telemetry for 20 s in each configuration. At the same time, AoPEI and Aortic Valve Closure (AVC) times were measured by Echo. Automatic EA analysis was carried out offline. AoPEI by EA was defined as the interval from the stimulus to the end of PEA I (TPEA1); AVC by EA was defined as the interval between TPEA1 and the onset of PEA II. ET by Echo was defined as the time interval between AoPEI and AVC on the echo tracings. Results AoPEI by Echo was 202.3±24.6 ms; AoPEI by EA was 196.1±29.9 ms (p=ns); correlation between the two was r=0.82 (p>0.0001). ET by Echo was 234.5±34.7 ms; ET by EA was 253.7±37.9 ms (p=ns); correlation between the two was r=0.74 (p>0.0001). Conclusion Echographic and EAbased estimation of systolic timings are well correlated. The chronical monitoring of such parameters by an implanted device using Endocardial Acceleration is attracting and opens new possibilites for day-by-day CRT therapy optimization.