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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.
Significance of new electrocardiographic parameters to improve cardiac resynchronization therapy
(2011)
Introduction: Oesophageal left heart electrogram (LHE) is a valuable tool providing electrocardiographic parameters for cardiac resynchronization therapy (CRT). It can be utilized to measure left ventricular (LVCD) and intra-leftventricular conduction delays (ILVCD) in heart failure patients to justify implantation of CRT systems. In the follow-up, LHE enables measurement of implant-related interatrial conduction times (IACT) which are the key intervals defining the hemodynamically optimal AV delay (AVD).
Methods: By TOSlim oesophageal electrode and Rostockfilter (Osypka AG, Rheinfelden, Germany), LHE was recorded in 39 heart failure patients (10f, 29m, 65±8yrs., QRS=163±21ms) after implantation of CRT systems according to guidelines. In position of maximal left ventricular deflection, LVCD and ILVCD were measured and compared with QRS width. In position of maximal left atrial deflection (LA), IACT was determined in VDD and DDD operation as interval As-LA and Ap-LA between atrial sense event (As) or stimulus (Ap), resp., and onset of LA. AVD was individualized using SAV =As-LA + 50ms for VDD and PAV=Ap-LA + 50ms for DDD operation.
Results: The CRT patients were characterized by minimal transoesophageal LVCD of 40ms but 73±20ms, at mean, ILVCD of 90±24ms and QRS/LVCD ratio of 2.4±0.6. The measured As-LA of 39±24ms and Ap-LA of 124±26ms resulted into SAV of 89±24ms and PAV of 174±26ms. In case of empirical AVD programming using 120ms for SAV and 180ms for PAV, the LHE revealed inverse sequences of LA and Vp in 4 patients (10%) during VDD and 13 patients (33%) in DDD pacing. In these patients, Vp preceded LA as IACT exceeded the programmed AVD.
Conclusion: Guideline indication of CRT systems is associated with LVCD of 40ms or more. Therefore, individual LVCD offers the minimal target interval that should be reached during left ventricular electrode placement to increase responder rate. Postoperatively, AV delay optimization respecting implant-related IACTs excludes adverse hemodynamic effects.
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.
Introduction: Cardiac resynchronization therapy (CRT) with left ventricular (LV) pacing is an established therapy for heart failure (HF) patients (P) with ventricular desynchronisation and reduced LV ejection fraction (EF). The aim of this study was to test the utilization of the transesophageal approach to measure arterial pulse pressure (PP) during LV pacing and electrical interventricular conduction delay (IVCD), to better select patients for CRT.
Methods: 32 HF patients (age 64 ± 10 years; 5 females, 27 males) with New York Heart Association (NYHA) class 2.8 ± 0.6, 27 ± 11 % LV EF and 155 ± 35 ms QRS duration were analysed with semi-invasive left cardiac pacing and electrocardiography. Esophageal TO8 Osypka catheter of 10.5 F diameter was perorally applied to the esophagus and placed in the position of maximum left atrial (LA) deflection and maximum LV deflection to measure PP with VAT or D00 pacing modes.
Results: Temporary transesophageal LV pacing was possible with VAT mode (n=16) and D00 mode (n=16) in all patients. In 15 Δ-PP-responders, PP was higher during LV pacing on than LV pacing off (78.3 ± 26.6 versus 65.9 ± 23.7 mmHg, P < 0.001) and NYHA class improved from 3.1 ± 0.35 to 2.1 ± 0.35 (P < 0.001) during 29 ± 26 month biventricular (BV) pacing follow-up (6 Medtronic and 9 Boston BV pacing devices). In 17 Δ-PP-non-responders, PP was not higher during LV pacing on than LV pacing off (61.5 ± 23.9 versus 60.9 ± 23.5 mmHg, P = 0.066). IVCD was significant longer in Δ-PP-responders than in Δ-PP-non-responders (87 ± 33 ms versus 37± 29 ms, P < 0.001).
Conclusion: Semi-invasive transesophageale LA and LV pacing with D00 and VAT mode and LV electrogram recording may be useful techniques to predict CRT improvement.
Semi-invasive electromechanical target interval to guide left ventricular electrode placement
(2011)
Using guideline parameters for indication of cardiac resynchronization therapy (CRT), only about two thirds of the patients improve clinically. Unfortunately both, surface ECG and echo are uncertain to predict CRT response. To better characterize cardiac desynchronization in heart failure, interventricular (IVCD) and intra-leftventricular conduction delays (ILVCD) were measured by esophageal left ventricular electrogram (LVE). Recordings in 43 CRT patients (34m, 9f, age: 64.7 ± 9.5yrs) evidenced only weak correlation between IVCD and QRS of 0.53 and between ILVCD and QRS of 0.33. This demonstrated that QRS duration is not a reliable indicator of desynchronization. Therefore, the study resulted into development of LVE feature for a programmer with implant support device. It can be used interoperatively to guide the left ventricular electrode location in order to increase responder rate in CRT.
Background: R-wave synchronised atrial pacing is an effective temporary pacing
therapy in infants with postoperative junctional ectopic tachycardia. In the technique
currently used, adverse short or long intervals between atrial pacing and ventricular
sensing (AP–VS) may be observed during routine clinical practice.
Objectives: The aim of the study was to analyse outcomes of R-wave synchronised
atrial pacing and the relationship between maximum tracking rates and AP–VS
intervals.
Methods: Calculated AP–VS intervals were compared with those predicted by experienced
pediatric cardiologist.
Results: A maximum tracking rate (MTR) set 10 bpm higher than the heart rate (HR)
may result in undesirable short AP–VS intervals (minimum 83 ms). A MTR set 20 bpm
above the HR is the hemodynamically better choice (minimum 96 ms). Effects of either
setting on the AP–VS interval could not be predicted by experienced observers. In our
newly proposed technique the AP–VS interval approaches 95 ms for HR > 210 bpm
and 130 ms for HR < 130 bpm. The progression is linear and decreases strictly
(− 0.4 ms/bpm) between the two extreme levels.
Conclusions: Adjusting the AP–VS interval in the currently used technique is complex
and may imply unfavorable pacemaker settings. A new pacemaker design is advisable
to allow direct control of the AP–VS interval.
Introduction: Radiofrequency ablation allows successful treatment of most supraventricular reentrant and focal tachycardias and an increasing number of ventricular tachycardias. Different catheter tips are used. While AV nodal reentrant tachycardias require catheters with a tip of 4mm length, an 8 mm tip electrodes will be used for atrial flutter. A pulmonary vein isolation will be performed using 4 mm irrigated tip electrodes to achieve larger and deeper lesions. The need of a tubing set and pump for saline transfusion is a disadvantage of this technique. Gold tip electrodes can alternatively be used to produce increases in lesion size. Aim of this study was to compare RF ablation catheters of exactly the same geometry with either platin-iridum or gold tip.
Methods: Gold provides an almost four-fold thermal conductivity compared with platinum-iridium. The Cerablate G flutter (Osypka AG, Rheinfelden-Herten) is a newly designed radiofrequency ablation catheter with an 8 mm gold tip. Its power delivery was compared with the Cerablate flutter of same geometry but platin-iridium tip. Therefore, in-vitro RF ablations were performed using pork meat in a 0.9% saline solution at 37°C temperature. A pulsed volume flow was generated using a pump to simulate the blood flow. Temperature controlled ablations of 60 seconds using 45, 55 and 65°C and a maximum of 70W RF power were performed.
Results: Using the Osypka HAT300smart ablator, cumulative power of 167, 474 and 672W was delivered with gold tip against 121, 227 and 310 W with platin-iridium tip. By the Stockert SmartAblate G4 ablator, 202, 546 and 1075W was delivered with gold tip against 117, 246 and 394W with platin-iridium using 45, 55 and 65°C temperature.
Conclusion: During in-vitro investigations, the gold tip electrodes allowed a in power delivery increase of 117 up to 173%. Thus, gold tips can be used to increase lesion depth and diameter without cooling equipment.
Introduction: Patient selection for cardiac resynchronization therapy (CRT) requires quantification of left ventricular conduction delay (LVCD). After implantation of biventricular pacing systems, individual AV delay (AVD) programming is essential to ensure hemodynamic response. To exclude adverse effects, AVD should exceed individual implant-related interatrial conduction times (IACT). As result of a pilot study, we proposed the development of a programmer-based transoesophageal left heart electrogram (LHE) recording to simplify both, LVCD and IACT measurement. This feature was implemented into the Biotronik ICS3000 programmer simultaneously with 3-channel surface ECG.
Methods: A 5F oesophageal electrode was perorally applied in 44 heart failure CRT-D patients (34m, 10f, 65±8 yrs., QRS=162±21ms). In position of maximum left ventricular deflection, oesophageal LVCD was measured between onsets of QRS in surface ECG and oesophageal left ventricular deflection. Then, in position of maximum left atrial deflection (LA), IACT in VDD operation (As-LA) was calculated by difference between programmed AV delay and the measured interval from onset of left atrial deflection to ventricular stimulus in the oesophageal electrogram. IACT in DDD operation (Ap-LA) was measured between atrial stimulus and LA..
Results: LVCD of the CRT patients was characterized by a minimum of 47ms with mean of 69±23ms. As-LA and Ap-LA were found to be 41±23ms and 125±25ms, resp., at mean. In 7 patients (15,9%), IACT measurement in DDD operation uncovered adverse AVD if left in factory settings. In this cases, Ap-LA exceeded the factory AVD. In 6 patients (13,6%), IACT in VDD operation was less than or equal 10ms indicating the need for short AVD.
Conclusion: Response to CRT requires distinct LVCD and AVD optimization. The ICS3000 oesophageal LHE feature can be utilized to measure LVCD in order to justify selection for CRT. IACT measurement simplifies AV delay optimization in patients with CRT systems irrespective of their make and model.
AV delay (AVD) optimization is mandatory in cardiac resynchronization (CRT) for heart failure. Several time consuming methods exist. We initialized development of left-atrial electrogram (LAE) feature for Biotronik ICS3000 programmer. It can be utilized to approximate optimal AV delay in CRT patients with pacing systems irrespective of make and model. Using this feature, we studied the share of interatrial conduction intervals (IACT) on individual echo AVD in 45 CRT patients (34m, 11f, mean age 69±6yrs.). The percentage of IACT on optimal echo AVD resulted in44.5±22.1% for VDD and 70.7±10.9% for DDD operation. In all patients, optimal echo AVDs exceeded the individual IACT by a duration of 52.5±33.3ms (p<0.001), at mean. Therefore, if AV delay optimization is not possible or not practicable in CRT patients, AVD should be approximated by individually measuring IACT and adding about 50ms.
Commercial simulators can only reproduce electrocardiograms (ECG) of the normal and diseased heart rhythm in a simplified waveform and with a low number of channels. With the presented project, the variety of digitally archived ECGs, recorded during electrophysiological examinations, should be made usable as original analogue signals for research and teaching purposes by the development of a special printed circuit board for the mini-computer “Raspberry-Pi “.
Special implant connection module was developed to combine full features of two commercial heart rhythm simulators, ARSI-4 and Intersim II, into a master-slave teaching system. Seven workstations were equipped with the Carelink and Homemonitoring remote patient monitoring systems. This combination enables in-vitro training of physicians, nurses and students in pace-maker and defibrillator measurements during implantation and individual programming in the follow-up. Thus, extended sets of arrhythmias and electrode problems can be used to simulate problems and their solutions in a wide range of the clinical routine.
Cardiac resynchronisation therapy (CRT) is a promising treatment option in patients with chronic heart failure. In this article the roles of semi-invasive esophageal left-heart electrocardiography and functional cardiac nuclear imaging in the field of CRT are highlighted, as the combination of both could be a favourable diagnostic approach in special cardiac situations. Also original esophageal left heart electrogram data of exemplary CRT patients is presented.
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.
About 20% of those heart failure patients receiving cardiac resynchronization therapy (CRT) are in atrial fibrillation (AF). Current guidelines apply for patients in sinus rhythm only. Recent studies have shown again, that successful resynchronization is closely linked to a pre-existent ventricular desynchronization. In those studies, the interventricular conduction delay (IVCD) was determined prior to device implantation by ultrasound in patients with sinus rhythm (SR)only. In patients with AF this method ́s use is limited.
To implement left-heart electrogram (LHE) into standard programmers and to simplify IVCD measurement in heart failure patients with AF, LHE was recorded in 11 AF patients with heart failure by Biotronik ICS3000 programmer via a15Hz Butterworth high-pass filter. Therefore, TOslim esophageal electrode (Dr. Osypka GmbH, Rheinfelden, Germany) was perorally applied and fixed in position of maximal left ventricular defection. IVCD was measured between onset of QRS in surface ECG and left ventricular defection (LV) in LHE. In addition, intra-left ventricular conduction delay (ILVCD) was measured as duration of LV in LHE.
In all of the 11 AF patients, desynchronization was quantifiable by LHE. Mean QRS of 162 ± 27ms (120-206ms) was linked with IVCD of 62ms ± 27ms (37-98ms) and ILVCD of 110 ± 20ms (80-144ms), at mean. Correlation between IVCD and QRS was 0.39 (n. s.) with IVCD/QRS ratio of 0.38 ± 0.11 (0.22-0.81).
A 15Hz high-pass filtered LHE feature of the Biotronik ICS3000 programmer is feasible to quantify ventricular dyssynchrony in heart failure patients with AF in order to clearly indicate implantation of CRT systems. As relations between QRS duration, IVCD and ILVCD considerably differ interindividually, the predictive values of IVCD, ILVCD and IVCD/QRS ratio for individual CRT response or non-response shall be identified in follow-up studies.
Non-fluoroscopic Imaging with MRT/CT Image Integration - Catheter Positioning with Double Precision
(2014)
Introduction: When antiarrhythmic drug therapy has failed, different approaches of pulmonary vein isolation are considered a reasonable option in the treatment of atrial fibrillation. It will be performed predominantly by radiofrequency catheter ablation. As the individual anatomy of left atrium and the pulmonary veins differs considerably, accurate visualization of these structures is essential during catheter positioning. Using non-fluoroscopic electroanatomic mapping system with image integration, electroanatomic mapping can be combined with highly detailed anatomical MRT or CT information on complex left atrial structures. This may facilitate catheter navigation during ablation for atrial fibrillation.
Methods: The CARTO XP electroanatomic system was used in a project during biomedical engineering study to practice image integration of anonymized real patients that underwent pulmonary vein isolation by CARTO XP and a MRT/CT procedure. Using the image integration software, MRT or CT images were imported into the CARTO XP system. The next process was segmentation of the acquired images. It involves dividing the images into different regions in order to select the structures of interest. In clinical routine, this segmentation has to be performed before catheter ablation. Then, the segmented images were aligned with the reconstructed electroanatomic maps. This consists of several steps, including selection of the left atrium, scaling of the reconstructed geometry, fusion of the structures using landmarks, and optimization of the integration by adjusting the reconstructed geometry of the left atrium.
Results: In the 3 months lasting period of the project, image integration was trained in 13 patients undergoing catheter ablation for atrial fibrillation. Within this period, time consumption for the process decreased from about 90 minutes at the beginning to about 35 minutes at the end for one patient.
Conclusion: Image integration into non-fluoroscopic electroanatomic map is a sophisticated tool in cardiac radiofrequency catheter ablation. Intensive training is necessary to control the procedure.
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.
AV delay (AVD) optimization can improve hemodynamics and avoid nonresponding to cardiac resynchronization therapy (CRT). AVD can be approximated by the sum of the individual implant-related interatrial conduction interval and a mean electromechanical interval of about 50ms. We searched for methods to facilitate automatic, implant-based AV delay optimization. In 25 patients (19m, 6f, age: 65±8yrs.) with Medtronic Insync III Marquis CRT-D series systems and left ventricular electrode at lateral or posterolateral wall, we determined interatrial conduction intervals by telemetric left ventricular tip versus superior vena cava coil electrogram (LVCE). Compared with esophageal measurements, the duration of optimal AV delay by LVCE showed good correlation (k=0.98, p=0.01) with a difference of 1.5±4.9ms, only. Therefore, LVCE is feasible to determine interatrial conduction intervals in order to automate AV delay optimization in CRT-D pacing promising increased accuracy compared to other algorithms.
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.
Langzeit-EKG-Scripte
(2016)
Die kardiale Resynchronisationstherapie ist ein großer Segen für viele Patienten mit einer Herzschwäche, die auf einen krankhaften Verlust der synchronen Kontraktion beider Herzkammern zurückzuführen ist. Warum einige von ihnen jedoch nicht darauf ansprechen, wird gegenwärtig erforscht. Als eine neue Methode mit dem Ziel der Effektivitätssteigerung dieser Therapie mit elektronischen Implantaten demonstrieren wir die Nutzbarkeit von durch eine Schluckelektrode aus der Speiseröhre abgeleiteten Elektrokardiogrammen.
In-vivo and in-vitro comparison of implant-based CRT optimization - What provide new algorithms?
(2011)
Introduction: In cardiac resynchronization therapy (CRT), individual AV delay (AVD) optimization can effectively increase hemodynamics and reduce non-responder rate. Accurate, automatic and easily comprehensible algorithms for the follow-up are desirable. QuickOpt is the first attempt of a semi-automatic intracardiac electrogram (IEGM) based AVD algorithm. We aimed to compare its accuracy and usefulness by in-vitro and in-vivo studies.
Methods: Using the programmable ARSI-4 four-chamber heart rhythm and IEGM simulator (HKP, Germany), the QuickOpt feature of an Epic HF system (St. Jude, USA) was tested in-vitro by simulated atrial IEGM amplitudes between 0.3 and 3.5mV during both, manual and automatic atrial sensing between 0.2 and 1.0mV. Subsequently, in 21 heart failure patients with implanted biventricular defibrillators, QuickOpt was performed in-vivo. Results of the algorithm for VDD and DDD stimulation were compared with echo AV delay optimization.
Results: In-vitro simulations demonstrated a QuickOpt measuring accuracy of ± 8ms. Depending on atrial IEGM amplitude, the algorithm proposed optimal AVD between 90 and 150ms for VDD and between 140 and 200ms for DDD operation, respectively. In-vivo, QuickOpt difference between individual AVD in DDD and VDD mode was either 50ms (20pts) or 40ms (1pt). QuickOpt and echo AVD differed by 41 ± 25ms (7 – 90ms) in VDD and by 18 ± 24ms (17-50ms) in DDD operation. Individual echo AVD difference between both modes was 73 ± 20ms (30-100ms).
Conclusion: The study demonstrates the value of in-vitro studies. It predicted QuickOpt deficiencies regarding IEGM amplitude dependent AVD proposals constrained to fixed individual differences between DDD and VDD mode. Consequently, in-vivo, the algorithm provided AVD of predominantly longer duration than echo in both modes. Accepting echo individualization as gold standard, QuickOpt should not be used alone to optimize AVD in CRT patients.
Introduction: Cardiac resynchronisation therapy (CRT) with atrioventricular (AV) and interventricular (VV) optimized biventricular pacing (BV) is an established therapy for heart failure (HF) patients with electrical interventricular conduction delay (IVCD). The aim of the study was to compare AV and VV delay optimization with cardiac output (CO) and acceleration index (ACI) impedance cardiographic (ICG) methods.
Methods: HF patients with IVCD 86.8 ± 33 ms (n=15, age 66 ± 10 years; 2 females, 13 males), New York Heart Association (NYHA) functional class 3.1 ± 0.4, left ventricular (LV) ejection fraction 21.3 ± 7.8 % and QRS duration 176.1 ± 31.7 ms underwent AV and VV delay optimization with CO and ACI methods (Cardioscreen, Medis GmbH, Ilmenau, Germany). After evaluation of optimal AV delay, we evaluated optimal VV delay during simultaneous LV and right ventricular (RV) pacing (LV=RV), LV before RV pacing (LV-RV) and RV before LV pacing (RV-LV).
Results: Optimal VV delay was -12.3 ± 25.9 ms LV-RV pacing with VV delay range from -80 ms LV-RV pacing to +20 ms RV-LV pacing and RV=LV pacing. Optimal AV delay after atrial sensing was 108.6 ± 20.3 ms (n=14) and optimal AV delay after atrial pacing 190 ± 14.1 ms (n=2) with AV delay range from 80 ms to 200 ms. RV versus BV pacing mode resulted in improvement of CO from 3.4 ± 1.2 l/min to 4.4 ± 1.4 l/min (p<0.001) and ACI from 0.667 ± 0.227 1/s² to 0.834 ± 0.282 1/s² (p<0.002). During 34 ± 26 month BV pacing, the NYHA class improved from 3.1 ± 0.4 to 2.1 ± 0.4 (p<0.001).
Conclusion: AV and VV delay optimized BV pacing acutely improve ICG CO and ACI and their NYHA class during long-term follow-up. ICG may be a simple and useful technique to optimize AV and VV delay in CRT.
Non-responder rate in cardiac resynchronization therapy (CRT) could be partly decreased by individualized parameter optimization excluding adverse hemodynamic timing. In heart failure patients with sinus rhythm, an atrial kick enables the completion of atrial contraction and may significantly enhance the ventricular filling. Compared to that, exclusion of atrial kick is a sign of suboptimal atrioventricular timing. However, the recognition of atrial kick by echocardiography will be negatively affected in patients requiring a very short or long AV delays.
Since direct current high energy shock fulguration was initially performed in the mid 1980s, ablation of cardiac arrhythmias has come to widespread use. Today the most frequently used energy source for catheter ablation is radio frequency (RF). It was the German engineer Peter Osypka who made available the HAT 100 as the first simple commercial RF ablator.
Nevertheless, in the first years of ablation, physicians were effectively working in the dark. Until today with an increasing understanding of arrhythmia mechanisms, both at the atrial and ventricular levels, this curative technology has made tremendous progress. Now, due to crucial improvement of RF ablation generators, temperature and contact force sensor catheters in combination with non-flouroscopic electroanatomical mapping technologies, computerized temperature and impedance controlled radiofrequency catheter ablation can be used to cure all types of arrhythmias including atrial and ventricular fibrillation. For the latter, cooled ablation by saline solution irrigated catheters has been developed to a widely used standard method. This procedure resulting in pulmonary vein isolation requires transseptal puncture and is technically demanding. Nevertheless, it has shown to be more effective than antiarrhythmic drug therapy.
While earliest RF ablations were performed with non-steerable catheters, today are used steerable sensor catheters without or with external and internal cooling and tips of 4mm or 8mm length. Further innovations like integration of mapping and cardiac imaging give exact information of the number of pulmonary veins and branching patterns and help to correlate electrical signals with anatomical structures.
The magnetic navigation significantly improved the success rates and safety of catheter ablation. Thus, in most cases RF catheter ablation has developed in the treatment of supraventricular arrhythmias from an alternative approach to drug therapy into the first therapeutic choice providing low complication rates.
In future, robotic navigation will further simplify procedures and reduce radiation exposure of this curative approach.
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.