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Currently, QRS width and bundle branch block morphology are used as electrocardiographic guideline criterias to selectheart failure (HF) patients with interventricular desynchronization in sinus rhythm (SR) for cardiac resynchronisationtherapy (CRT). Nevertheless, up to 30% of these patients do not benefit from implantation of CRT systems. Esophagealleft ventricular electrogram (LVE) enables semi-invasive measurement of interventricular conduction delays (IVCD)even in patients with atrial fibrillation (AF). To routinely apply this method, a programmer based semi-invasiveautomatic quantification of IVCD should to be developed. Our aims were todefine interventricular conduction delaysby analyzing fractionated left ventricular (LV) deflections in the esophageal left ventricular electrogram of HF patientsin SR or AF.
In 66 HF patients (49 male,17 female, age 65 ± 10 years) a 5F TOslim electrode (Osypka AG, Germany) was perorallyapplied. Using BARD EP Lab, cardiac desynchronization was quantified as interval IVCD between onset of QRS insurface ECG and the investigator-determined onset of the left ventricular deflection in LVE. IVCD was compared withthe intervals between QRS onset and the first maximum (IVCDm1) and between QRS onset and the second maximum(IVCDm2) of the LV complex.
QRS of 173 ± 26 ms was linked with empirical IVCD of 75 ± 25 ms, at mean. First and second LV maximum could beascertained beyond doubt in all patients. Significant correlations of the p<0,01 level were found between IVCD and theIVCDm1 of 96 ± 28 ms as well as between IVCD and the IVCDm2 of 147 ± 31 ms, at mean. To standardize automatic measurement of interventricular conduction delays with respect to patients with fractionatedLV complexes, the first maximum of the LV deflection should be utilized to qualify the IVCD of HF patients with sinusrhythm and atrial fibrillation.
Cardiac resynchronization therapy (CRT) with biventricular (BV) pacing is an established therapy in approximately two-thirds of symptomatic heart failure (HF) patients (P) with left bundle branch block (LBBB). The aim of this study was to evaluate left atrial (LA) conduction delay (LACD) and left ventricular (LV) conduction delay (LVCD) using pre-implantational transesophageal electrocardiography (ECG) in sinus rhythm (SR) CRT responder (R) and non-responder (NR).
Methods: SR HF P (n=52, age 63.6±10.4 years; 6 females, 46 males) with New York Heart Association (NYHA) class 3.0±0.2, 24.4±7.1 % LV ejection fraction and 171.2±37.6 ms QRS duration (QRSD) were measured by bipolar filtered transesophageal LA and LV ECG recording with hemispherical electrodes (HE) TO catheter (Osypka AG, Rheinfelden, Germany). LACD was measured between onset of P-wave in the surface ECG and onset of LA deflection in the LA ECG. LVCD was measured between onset of QRS in the surface ECG and onset of LV deflection in the LV ECG.
Results: There were 78.8 % SR CRT R (n=41) with 171.2±36.9 ms QRSD, 73.3±25.7 ms LACD, 80.0±24.0 ms LVCD and 2.3±0.5 QRSD-LVCD-ratio. SR CRT R QRSD correlated with LACD (r=0.688, P<0.001) and LVCD (r=0.699, P<0.001). There were 21.2 % SR CRT NR (n=11) with 153.4±22.4 ms QRSD (P=0.133), 69.8±24.8 ms LACD (n=6, P=0.767), 54.2±31.0 ms LVCD (P<0.0046) and 3.9±2.5 QRSD-LVCD-ratio (P<0.001). SR CRT NR QRSD not corre-lated with IACD (r=-0.218, P=0.678) and IVCD (r=0.042, P=0.903). During a 22.8±21.3 month CRT follow-up, the CRT R NYHA class improved from 3.1±0.3 to 1.9±0.3 (P<0.001). In CRT NR, NYHA class not improved (2.9±0.4 to 2.9±0.2, P=1) during 11.2±9.8 months BV pacing.
Conclusions: Transesophageal LA and LV ECG with HE can be utilized to analyse LACD and LVCD in HF P. Pre-implantational LVCD and QRSD-LVCD-ratio may be additional useful parameters to improve P selection for SR CRT.
Capture threshold (CT) for transesophageal left atrial (LA) pacing (TLAP) and transesophageal left ventricular (LV) pacing (TLVP) with conventional cylindrical electrodes (CE) are higher than TLAP feeling threshold (FT). Purpose of the study was to evaluate focused TLAP CT and FT for supraventricular tachycardia (SVT) initiation and focused TLVP CT for cardiac resynchronisation therapy (CRT) simulation.
Methods: SVT initiation in patients (P) with palpitations (n=49, age 47 ± 17 years) was analysed during spontaneous rhythm and during focused bipolar TLAP with atrial constant current stimulus output, distal CE and three or seven 6 mm hemispherical electrodes (HE) (TO, Osypka AG, Rheinfelden, Germany). CRT simulation in heart failure P (n=75, age 62 ± 11 years) was evaluated by focused bipolar TLAP and/or TLVP with ventricular constant voltage stimulus output and different pacing mode.
Results: Focused electrical pacing field between CE and HE (n=28) allowed low threshold TLAP with 8.0 ± 2.6 mA CT at 9.9 ms stimulus duration (SD) which was lower than 9.2 ± 4.5 mA FT at 9.9 ms SD. Focused electrical pacing field between HE and HE (n=21) allowed low threshold TLAP with 8.1 ± 2.2 mA CT at 9.9 ms SD which was lower than 9.8 ± 5.0 mA FT at 9.9 ms SD. SVT initiation by programmed AAI TLAP was possible in 23 P and not possible in 26 P. CRT simulation was evaluated with TLAP and TLVP with VAT, D00 and V00 pacing mode and 95.5 ± 10.9 V TLVP CT at 4.0 ms SD.
Conclusions: Programmed focused AAI TLAP allowed initiation of SVT with very low CT and high FT and focused electrical pacing field between CE-HE and HE-HE.CRT simulation with focused TLAP and/or TLVP with VAT, D00 and V00 pacing mode may be a useful technique to detect responders to CRT.
ECG simulators, available on the market, imitate the electric activity of the heart in a simplified manner. Thus, they are suitable for education purposes but not really for testing algorithms to recognize complex arrhythmias needed for pacemakers and implantable defibrillators. Especially certain discrimination between various morphologies of atrial and ventricular fibrillation needs simulators providing native electrograms of different patients’ heart rhythm events. This explains the necessity to develop an ECG simulator providing high-resolution native intracardiac and surface electrograms of in-vivo rhythm events. In this paper we demonstrate an approach for an ECG simulator based on a consumer multichannel soundcard and a corresponding software application for a laptop computer. This Live-ECG Simulator is able to handle invasive electrogram recordings from electrophysiological studies and send the data to a modified external soundcard for subsequent digital to analog conversion. The hardware is completed with an electronic circuit providing level adjustment to adapt the output amplitude to the input conditions of several cardiac implants.
In cardiac resynchronization therapy (CRT) for heart failure, individualization of the AV delay is essential to improve hemodynamics and to minimize non-responder rate. In patients in sinus rhythm having additional disposition to bradycardia, optimization is necessary for both situations, atrial sensing and pacing. Therefore, echo-optimization is the goldstandard but time consuming. Unfortunately, it depends on the particular CRT systems parameter set if the resulting individually optimal AV delays can be programmed or not. Some CRT systems provide a set of AV delays for DDD operation combined with a set of the pace-sense-compensation to optimize the AV delay in DDD and VDD operation. The pace-sense-compensation (PSC) can be defined by the difference of implant-related interatrial conduction intervals in DDD and VDD operation measured in the esophageal left atrial electrogram. In a cohort of 96 CRT patients we found mean PSC of 59-35ms ranging between 0-143ms. As a consequence, allowing 10ms tolerance, AVD optimization is completely impossible in one of the two modes, VDD or DDD operation, in 34 (35%) or 5 (5%) patients with implants restricting the PSC range to 60ms or 100ms, respectively. Thus, we propose companies to provide CRT systems with programmable pace-sense- compensation between 0ms and 150ms.
Responder-rate in cardiac resynchronization therapy (CRT) of patients in sinus rhythm (SR) or atrial fibrillation (AF) mainly depends on accurat selection, optimal position of the left ventricular electrode and individualization of hemodynamical parameters of the implanted biventricular pacing system during follow-up. High resolution esophageal left heart electrocardiography offers a quick and semi-invasive approach to the electrical activity of left atrium and left ventricle. It was used in 62 heart failure patients in sinus rhythm and 11 in atrial fibrillation after implantation of CRT systems to compare the semi-invasive interventricular conduction delay (IVCDE) with QRS width. In all of the patients, guideline decision for CRT was linked with IVCDE of about 40ms and up. From logical point of view, IVCDE provides the minimal target interval for the left ventricular electrode placement in order to exclude non-responders. Esophageal measurement of interatrial conduction intervals in VDD and DDD pacing was utilized to individualize the AV delay and to exclude adverse hemodynamic effects.
New frontiers of supraventricular tachycardia and atrial flutter evaluation and catheter ablation
(2012)
Radiofrequency catheter ablation (RFCA) has revolutionized treatment for tachyarrhythmias and has become first-line therapy for some tachycardias. Although developed in the 1980s and widely applied in the 1990s, the technique is still in development. Transesophageal atrial pacing (TAP) can used for initiation and termination of supraventricular tachycardia (SVT).
Methods: The paroxysmal SVT include a wide spectrum of disorders including, in descending order of frequency, atrial flutter, atrioventricular (AV) nodal reentry, Wolff-Parkinson-White syndrome, and atrial tachycardia. While not life-threatening in most cases, they may cause important symptoms, such as palpitations, chest discomfort, breathlessness, anxiety, and syncope, which significantly impair quality of life. Medical therapy has variable efficacy, and most patients are not rendered free of symptoms. Research over the past several decades has revealed fundamental mechanisms involved in the initiation and maintenance of all of these arrhythmias. Knowledge of mechanisms has in turn led to highly effective surgical and catheter-based treatments. The supraventricular arrhythmias and their treatment are described in this report. SVT initiation was analysed with programmed TAP in 49 patients with palpitations (age 47 ± 17 years, 24 females, 25 males).
Results: In comparison to antiarrhythmic drug therapy the radiofrequency catheter ablation in patients suffering from atrial flutter, atrioventricular nodal reentry, atrioventricular reentry and atrial tachycardia is the better choice in most cases. TAP SVT initiation was possible in 23 patients before RFCA. Atrial cycle length of SVT was 320 ± 59 ms. We initiated AV nodal reentrant tachycardia (AVNRT, n=15), atrial tachycardia (AT, n=6) and AV reentrant tachycardia with Kent pathway conduction (AVRT, n=2) before RFCA.
Conclusions: Radiofrequency catheter ablation is a successful and safe method to cure most patients with paroxysmal supraventricular tachycardias. TAP allowed initiation and termination of SVT especially in outpatients.
Cardiac resynchronization therapy (CRT) with biventricular pacing is an established therapy for heart failure (HF) patients (P) with ventricular desynchronization and reduced left ventricular (LV) ejection fraction. The aim of this study was to evaluate electrical right atrial (RA), left atrial (LA), right ventricular (RV) and LV conduction delay with novel telemetric signal averaging electrocardiography (SAECG) in implantable cardioverter defibrillator (ICD) P to better select P for CRT and to improve hemodynamics in cardiac pacing.
Methods: ICD-P (n=8, age 70.8 ± 9.0 years; 2 females, 6 males) with VVI-ICD (n=4), DDD-ICD (n=3) and CRT-ICD (n=1) (Medtronic, Inc., Minneapolis, MN, USA) were analysed with telemetric ECG recording by Medronic programmer 2090, ECG cable 2090AB, PCSU1000 oscilloscope with Pc-Lab2000 software (Velleman®) and novel National Intruments LabView SAECG software.
Results: Electrical RA conduction delay (RACD) was measured between onset and offset of RA deflection in the RAECG. Interatrial conduction delay (IACD) was measured between onset of RA deflection and onset of far-field LA deflection in the RAECG. Interventricular conduction delay (IVCD) was measured between onset of RV deflection in the RVECG and onset of LV deflection in the LVECG. Telemetric SAECG recording was possible in all ICD-P with a mean of 11.7 ± 4.4 SAECG heart beats, 97.6 ± 33.7 ms QRS duration, 81.5 ± 44.6 ms RACD, 62.8 ± 28.4 ms RV conduction delay, 143.7 ± 71.4 ms right cardiac AV delay, 41.5 ms LA conduction delay, 101.6 ms LV conduction delay, 176.8 ms left cardiac AV delay, 53.6 ms IACD and 93 ms IVCD.
Conclusions: Determination of RA, LA, RV and LV conduction delay, IACD, IVCD, right and left cardiac AV delay by telemetric SAECG recording using LabView SAECG technique may be useful parameters of atrial and ventricular desynchronization to improve P selection for CRT and hemodynamics in cardiac pacing.
Cardiac resynchronization therapy with biventricular pacing is an established therapy for heart failure patients with electrical left ventricular desynchronization. The aim of this study was to evaluate left atrial conduction delay, intra left atrial conduction delay, left ventricular conduction delay and intra left ventricular conduction delay in heart failure patients using novel signal averaging transesophageal left heart ECG software.
Methods: 8 heart failure patients with dilated cardiomyopathy (DCM), age 68 ± 9 years, New York Heart Association (NYHA) class 2.9 ± 0.2, 24.8 ± 6.7 % left ventricular ejection fraction, 188.8 ± 15.5 ms QRS duration and 8 heart failure patients with ischaemic cardiomyopathy (ICM), age 67 ± 8 years, NYHA class 2.9 ± 0.3, 32.5 ± 7.4 % left ventricular ejection fraction and 167.6 ± 19.4 ms QRS duration were analysed with transesophageal and transthoracic ECG by Bard LabDuo EP system and novel National Intruments LabView signal averaging ECG software.
Results: The electrical left atrial conduction delay was 71.3 ± 17.6 ms in ICM versus 72.3 ± 12.4 ms in DCM, intra left atrial conduction delay 66.8 ± 8.6 ms in ICM versus 63.4 ± 10.9 ms in DCM and left cardiac AV delay 180.5 ± 32.6 ms in ICM versus 152.4 ± 30.4 ms in DCM. The electrical left ventricular conduction delay was 40.9 ± 7.5 ms in ICM versus 42.6 ± 17 ms in DCM and intra left ventricular conduction delay 105.6 ± 19.3 ms in ICM versus 128.3 ± 24.1 ms in DCM.
Conclusions: Left heart signal averaging ECG can be utilized to analyse left atrial conduction delay, intra left atrial conduction delay, left ventricular conduction delay and intra left ventricular conduction delay to improve patient selection for cardiac resynchronization therapy.