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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.
This paper shows the results of the evaluation of two sets of mobile web design guidelines concerning mobile learning. The first set of guidelines is concerned with the usage of text on mobile device screens. The second set is concerned with the usage of images on mobile devices. The evaluation is performed by eye tracking (objective) as well as questionnaires and interviews (subjective) respectively.
This paper explores the potential of an m-learning environment by introducing the concept of mLab, a remote laboratory environment accessible through the use of handheld devices.
We are aiming to enhance the existing e-learning platform and internet-assisted laboratory settings, where students are offered in-depth tutoring, by providing compact tuition and tools for controlling simulations that are made available to learners via handheld devices. In this way, students are empowered by having access totheir simulations from any place and at any time.
Transthoracic impedance cardiography (ICG) is a non-invasive method for determination of hemodynamic parameters. The basic principle of transthoracic ICG is the measurement of electrical conductivity of the thorax over the time. The aim of the study was the analysis of hemodynamic parameters from healthy individuals and the evaluation of various hemodynamic monitoring devices. Fourteen men (mean age 25 ± 4.59 years) and twelve women (mean age 24 ± 3.5 years) were measured during the cardiovascular engineering laboratory at Offenburg University of Applied Sciences, Offenburg, Germany. The ICG recordings were measured with the devices CardioScreen 1000, CardioScreen 2000 and TensoScreen with the corresponding Software Cardiovascular Lab 2.5 (Medis Medizinische Messtechnik GmbH, Illmenau, Germany). In order to create identical frame conditions, all measurements were recorded in the same position and for the same duration. Various positions were simulated from horizontal lying position to vertical standing position. Altogether, more than 30 hemodynamic parameters were measured.
In contrast to conventional aortic valve replacement, the Transcatheter Aortic Valve Implantation (TAVI) is a new highly specialist alternative to surgical valve replacement for patients with symptomatic severe aortic stenosis and high operative risk. The procedure was performed in a minimally invasive way and was introduced at the university heart centre, Freiburg – Bad Krozingen in 2008. The results have been getting better and better over the years. The aim of the investigation is the analysis of electrocardiogram conduction time and the electrocardiography changes recorded hours and days after the procedure depending on artificial heart valve models, which may lead to pacemaker implantation, even the analysis of the effectiveness of treatment.
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.
Introduction: Despite lots of developments in the last years, radiofrequency ablation of rhythm diseases is a safe but still complex procedure that requires special experience and expertise of the physicians and biomedical engineers. Thus, there is a need of special trainings to become familiar with the different equipment and to explain several effects that can be observed during clinical routine.
Methods: The Offenburg University of Applied Sciences offers a biomedical engineering study path specialized in the fields of cardiology, electrophysiology and cardiac electronic implants. It`s Peter Osypka Institute for Pacing and Ablation provides teaching following the slogan “Learning by watching, touching and adjusting”. It conducts lots of trainings for students as well as young physicians interested in electrophysiology and radiofrequency ablation.
Results: In-vitro trainings will be provided using the Osypka HAT 200 and HAT300s, Stockert EPshuttle and SmartAblate system as well as the Boston EPT-1000XP and Maestro 3000 and the Radionics RFG-3E cardiac radio frequency ablation generators. All of them require different handling as well as special accessories like catheter connection cables or boxes and back plates. The participants will be trained in the setup of temperature, power and cut-off impedance dependent on different ablation catheters. Furthermore troubleshooting in hard- and software is part of the program. Performing procedures in pork or animal protein and using physiological saline solution to simulate the blood flow, they can study the influence of contact force and impedance on lesion geometry etc. and to avoid adverse effects like “plops”. Lots of catheter types are available: 4mm tip, 8mm standard and gold tip, open and closed irrigated tip ablation catheters of different companies. The experiments will be completed by measuring the lesion size dependent on the used catheter type and ablation settings.
Conclusion: In-vitro training in radiofrequency ablation is a challenge for biomedical engineering students and young physicians.
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.
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: To simplify AV delay (AVD) optimization in cardiac resynchronization therapy (CRT), we reported that the hemodynamically optimal AVD for VDD and DDD mode CRT pacing can be approximated by individually measuring implant-related interatrial conduction intervals (IACT) in oesophageal electrogram (LAE) and adding about 50ms. The programmer-based St Jude QuickOpt algorithm is utilizing this finding. By automatically measuring IACT in VDD operation, it predicts the sensed AVD by adding either 30ms or 60ms. Paced AVD is strictly 50ms longer than sensed AVD. As consequence of those variations, several studies identified distinct inaccuracies of QuickOpt. Therefore, we aimed to seek for better approaches to automate AVD optimization.
Methods: In a study of 35 heart failure patients (27m, 8f, age: 67±8y) with Insync III Marquis CRT-D systems we recorded telemetric electrograms between left ventricular electrode and superior vena cava shock coil (LVtip/SVC = LVCE) simultaneously with LAE. By LVCE we measured intervals As-Pe in VDD and Ap-Pe in DDD operation between right atrial sense-event (As) or atrial stimulus (Ap), resp., and end of the atrial activity (Pe). As-Pe and Ap-Pe were compared with As-LA an Ap-LA in LAE, respectively.
Results: End of the left atrial activity in LVCE could clearly be recognized in 35/35 patients in VDD and 29/35 patients in DDD operation. We found mean intervals As-LA of 40.2±24.5ms and Ap-LA of 124.3±20.6ms. As-Pe was 94.8±24.1ms and Ap-Pe was 181.1±17.8ms. Analyzing the sums of As-LA + 50ms with duration of As-Pe and Ap-LA + 50ms with duration of Ap-Pe, the differences were 4.7±9.2ms and 4.2±8.6ms, resp., only. Thus, hemodynamically optimal timing of the ventricular stimulus can be triggered by automatically detecting Pe in LVCE.
Conclusion: Based on minimal deviations between LAE and LVCE approach, we proposed companies to utilize the LVCE in order to automate individual AVD optimization in CRT pacing.
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.
Cardiac resynchronization therapy is an established therapy for heart failure patients with sinus rhythm, reduced left ventricular ejection fraction and prolongation of QRS duration. The aim of the study was to evaluate ventricular desynchronization with electrical interventricular delay (IVD) to left ventricular delay (LVD) ratio in atrial fibrillation heart failure patients. IVD and LVD were measured by transesophageal posterior left ventricular ECG recording. In atrial fibrillation heart failure patients with prolonged QRS duration, the mean IVD-to-LVD-ratio was 0.84 +/- 0.42 with a range from 0.17 to 2.2 IVD-to-LVD-ratio. IVD-to-LVD-ratio correlated with QRS duration. IVD-to-LVD-ratio may be a useful parameter to evaluate electrical ventricular desynchronization in atrial fibrillation heart failure patients.
Cardiac resynchronization therapy with atrioventricular and interventricular pacing delay optimized biventricular pacing is an established therapy for heart failure patients with sinus rhythm and reduced left ventricular ejection fraction. The aim of the study was to evaluate atrioventricular and interventricular pacing delay optimization in cardiac resynchroniza-tion therapy by transthoracic impedance cardiography in biventricular pacing with different left ventricular electrode po-sition. In biventricular pacing heart failure patients with lateral, posterolateral and anterolateral left ventricular electrode position, the mean optimal atrioventricular sening delay was 108.6 ± 20.3 ms and the mean optimal interventricular pac-ing delay -12.3 ± 25.9 ms. Transthoracic impedance cardiography may be a useful technique to optimize atrioventricular and interventricular pacing delay in biventricular pacing with different left ventricular electrode position.
Distribution of esophageal interventricular conduction delays in CRT patients and healthy subjects
(2015)
Background: Cardiac resynchronization therapy (CRT) is an established therapy for heart failure (HF) patients (P) with reduced left ventricular (LV) ejection fraction and electrical interventricular desynchronization, but not all P improved clinically. The aim of the study was to evaluate electrical interventricular delay (IVD) to LV delay (LVD) ratio in atrial fibrillation (AF) CRT responder (R) and non-responder (NR).
Methods: AF P (n = 18, age 60.6 ± 11.4 years, 1 female, 17 males) with HF New York Heart Association (NYHA) class 3.0 ± 0.2, 25.3 ± 5.9 % LV ejection fraction and 157.8 ± 24.4 ms QRS duration (QRSD) were measured by surface ECG and focused transesophageal bipolar LV ECG before implantation of CRT pacemaker (n = 2) or CRT defibrillator (n = 16). IVD was measured between onset of QRS in the surface ECG and onset of LV signal in the LV ECG. LVD was measured between onset and offset of LV signal in the LV ECG.
Results: Electrical ventricular desynchronization in AF CRT P were 61.9 ± 26.9ms IVD, 80.6 ± 24.3ms LVD, 0.85 ± 0.41 IVD-LVD-ratio (Figure), 3.12 ± 1.89 QRSD-IVD-ratio and 2.07 ± 0.47 QRSD-LVD-ratio. There were 72.2 % AF CRT R (n = 13) with 64.2 ± 24.6ms IVD and 77.8 ± 21.6ms LVD with Pearson correlation to 0.89 ± 0.39 IVD-LVD-ratio (r = 0.87, P < 0.01; r = -0.69, P < 0.01), 2.82 ± 1.32 QRSD-IVD-ratio (r = -0.76, P < 0.01; r = 0.67, P = 0.011) and 2.13 ± 0.46 QRSD-LVD-ratio (r = 0.57, P = 0.041; r = -0.85, P < 0.01). There were 27.8% AF CRT NR (n = 5) with 56.0 ± 34.5ms IVD and 87.8 ± 31.9ms LVD without correlation to 0.74 ± 0.48 IVD-LVD-ratio, 3.88 ± 2.98 QRSD-IVD-ratio and 1.90 ± 0.48 QRSD-LVD-ratio. During 15.3 ± 13.1 month CRT follow-up, the AF CRT R NYHA class improved from 3.0 ± 0.2 to 2.2 ± 0.3 (P < 0.001). During 18.8 ± 20.7 month CRT follow-up, the AF CRT NR NYHA class not improved from 3 to 3.3 ± 0.97.
The electrical field (E-field) of the biventricular (BV) stimulation is important for the success of cardiac resynchronization therapy (CRT) in patients with cardiac insufficiency and widened QRS complex.
The aim of the study was to model different pacing and ablation electrodes and to integrate them into a heart model for the static and dynamic simulation of BV stimulation and HF ablation in atrial fibrillation (AF).
The modeling and simulation was carried out using the electromagnetic simulation software CST. Five multipolar left ventricular (LV) electrodes, four bipolar right atrial (RA) electrodes, two right ventricular (RV) electrodes and one HF ablation catheter were modelled. A selection were integrated into the heart rhythm model (Schalk, Offenburg) for the electrical field simulation. The simulation of an AV node ablation at CRT was performed with RA, RV and LV electrodes and integrated ablation catheter with an 8 mm gold tip.
The BV stimulation were performed simultaneously at amplitude of 3 V at the LV electrode and 1 V at the RV electrode with a pulse width of 0.5 ms each. The far-field potential at the RA electrode tip was 32.86 mV and 185.97 mV at a distance of 1 mm from the RA electrode tip. AV node ablation was simulated with an applied power of 5 W at 420 kHz at the distal ablation electrode. The temperature at the catheter tip was 103.87 °C after 5 s ablation time and 37.61 °C at a distance of 2 mm inside the myocardium. After 15 s, the temperature was 118.42 °C and 42.13 °C.
Virtual heart and electrode models as well as the simulations of electrical fields and temperature profiles allow the static and dynamic simulation of atrial synchronous BV stimulation and HF ablation at AF and could be used to optimize the CRT and AF ablation.
Spectral analysis of signal averaging electrocardiography in atrial and ventricular tachyarrhythmias
(2017)
Background: Targeting complex fractionated atrial electrograms detected by automated algorithms during ablation of persistent atrial fibrillation has produced conflicting outcomes in previous electrophysiological studies. The aim of the investigation was to evaluate atrial and ventricular high frequency fractionated electrical signals with signal averaging technique.
Methods: Signal averaging electrocardiography (ECG) allows high resolution ECG technique to eliminate interference noise signals in the recorded ECG. The algorithm uses automatic ECG trigger function for signal averaged transthoracic, transesophageal and intracardiac ECG signals with novel LabVIEW software (National Instruments, Austin, Texas, USA). For spectral analysis we used fast fourier transformation in combination with spectro-temporal mapping and wavelet transformation for evaluation of detailed information about the frequency and intensity of high frequency atrial and ventricular signals.
Results: Spectral-temporal mapping and wavelet transformation of the signal averaged ECG allowed the evaluation of high frequency fractionated atrial signals in patients with atrial fibrillation and high frequency ventricular signals in patients with ventricular tachycardia. The analysis in the time domain evaluated fractionated atrial signals at the end of the signal averaged P-wave and fractionated ventricular signals at the end of the QRS complex. The analysis in the frequency domain evaluated high frequency fractionated atrial signals during the P-wave and high frequency fractionated ventricular signals during QRS complex. The combination of analysis in the time and frequency domain allowed the evaluation of fractionated signals during atrial and ventricular conduction.
Conclusions: Spectral analysis of signal averaging electrocardiography with novel LabVIEW software can utilized to evaluate atrial and ventricular conduction delays in patients with atrial fibrillation and ventricular tachycardia. Complex fractionated atrial electrograms may be useful parameters to evaluate electrical cardiac arrhythmogenic signals in atrial fibrillation ablation.
Heart rhythm model and simulation of electrophysiological studies and high-frequency ablations
(2017)
Background: The simulation of complex cardiologic structures has the potential to replace clinical studies due to its high efficiency regarding time and costs. Furthermore, the method is more careful for the patients’ health than the conventional ways. The aim of the study was to create an anatomic CAD heart rhythm model (HRM) as accurate as possible, and to show its usefulness for cardiac electrophysiological studies (EPS) and high-frequency (HF) ablations.
Methods: All natural heart components of the new HRM were based on MRI records, which guaranteed electronic functionality. The software CST (Computer Simulation Technology, Darmstadt) was used for the construction, while CST’s material library assured genuine tissue properties. It should be applicable to simulate different heart rhythm diseases as well as various diffusions of electromagnetic fields, caused by electrophysiological conduction, inside the heart tissue.
Results: It was achievable to simulate normal sinus rhythm and fourteen different heart rhythm disturbance with different atrial and ventricular conduction delays. The simulated biological excitation of healthy and sick HRM were plotted by simulated electrodes of four polar right atrial catheter, six polar His bundle catheter, ten polar coronary sinus catheter, four polar ablation catheter and eight polar transesophageal left cardiac catheter (Fig.). Accordingly, six variables were rebuilt and inserted into the anatomic HRM in order to establish heart catheters for ECG monitoring and HF ablation. The HF ablation catheters made it possible to simulate various types of heart rhythm disturbance ablations with different HF ablation catheters and also showed a functional visualisation of tissue heating. The use of tetrahedral meshing HRM made it attainable to store the results faster accompanied by a higher degree of space saving. The smart meshing function reduced unnecessary high resolutions for coarse structures.
Conclusions: The new HRM for EPS simulation may be additional useful for simulation of heart rhythm disturbance, cardiac pacing, HF ablation and for locating and identification of complex fractioned signals within the atrium during atrial fibrillation HF ablation.
Heart rhythm model and simulation of electrophysiological studies and high-frequency ablations
(2017)
Background: The simulation of complex cardiologic structures has the potential to replace clinical studies due to its high efficiency regarding time and costs. Furthermore, the method is more careful for the patients’ health than the conventional ways. The aim of the study was to create an anatomic CAD heart rhythm model (HRM) as accurate as possible, and to show its usefulness for cardiac electrophysiological studies (EPS) and high-frequency (HF) ablations.
Methods: All natural heart components of the new HRM were based on MRI records, which guaranteed electronic functionality. The software CST (Computer Simulation Technology, Darmstadt) was used for the construction, while CST’s material library assured genuine tissue properties. It should be applicable to simulate different heart rhythm diseases as well as various diffusions of electromagnetic fields, caused by electrophysiological conduction, inside the heart tissue.
Results: It was achievable to simulate normal sinus rhythm and fourteen different heart rhythm disturbance with different atrial and ventricular conduction delays. The simulated biological excitation of healthy and sick HRM were plotted by simulated electrodes of four polar right atrial catheter, six polar His bundle catheter, ten polar coronary sinus catheter, four polar ablation catheter and eight polar transesophageal left cardiac catheter (Fig.). Accordingly, six variables were rebuilt and inserted into the anatomic HRM in order to establish heart catheters for ECG monitoring and HF ablation. The HF ablation catheters made it possible to simulate various types of heart rhythm disturbance ablations with different HF ablation catheters and also showed a functional visualisation of tissue heating. The use of tetrahedral meshing HRM made it attainable to store the results faster accompanied by a higher degree of space saving. The smart meshing function reduced unnecessary high resolutions for coarse structures.
Conclusions: The new HRM for EPS simulation may be additional useful for simulation of heart rhythm disturbance, cardiac pacing, HF ablation and for locating and identification of complex fractioned signals within the atrium during atrial fibrillation HF ablation.
Background: Cardiac resynchronization therapy (CRT) with biventricular (BV) pacing is an established therapy for heart failure (HF) patients (P) with sinus rhythm, reduced left ventricular (LV) ejection fraction (EF) and electrical ventricular desynchronization. The aim of the study was to evaluate electrical interventricular delay (IVD) and left ventricular delay (LVD) in right ventricular (RV) pacemaker pacing before upgrading to CRT BV pacing.
Methods: HF P (n=11, age 69.0 ± 7.9 years, 1 female, 10 males) with DDD pacemaker (n=10), DDD defibrillator (n=1), RV pacing, New York Heart Association (NYHA) class 3.0 ± 0.2 and 24.5 ± 4.9 % LVEF were measured by surface ECG and transesophageal bipolar LV ECG before upgrading to CRT defibrillator (n=8) and CRT pacemaker (n=3). IVD was measured between onset of QRS in the surface ECG and onset of LV signal in the transesophageal ECG. LVD was measured between onset and offset of LV signal in the transesophageal ECG. CRT atrioventricular (AV) and BV pacing delay were optimized by impedance cardiography.
Results: Interventricular and intraventricular desynchronization in RV pacemaker pacing were 228.2 ± 44.8 ms QRS duration, 86.5 ± 32.8ms IVD, 94.4 ± 23.8ms LVD, 2.6 ± 0.8 QRS-IVD-ratio with correlation between IVD and QRS-IVD-ratio (r=-0.668 P=0.0248) and 2.3 ± 0.7 QRS-LVD-ratio. The LVEF-IVD-ratio was 0.3 ± 0.1 with correlation between IVD and LVEF-IVD-ratio (r=-0.8063 P=0.00272) and with correlation between QRS duration and LVEF-IVD-ratio (r=-0.7251 P=0.01157). Optimal sensing and pacing AV delay were 128.3 ± 24.8 ms AV delay after atrial sensing (n=6) and 173.3 ± 40.4 ms AV delay after atrial pacing (n=3). Optimal BV pacing delay was -4.3 ± 11.3 ms between LV and RV pacing (n=7). During 30.4 ± 29.6 month CRT follow-up, the NYHA class improved from 3.1 ± 0.2 to 2.2 ± 0.3.
Conclusions: Transesophageal electrical IVD and LVD in RV pacemaker pacing may be additional useful ventricular desynchronization parameters to improve P selection for upgrading RV pacemaker pacing to CRT BV pacing.
Background: The electrical field (E-field) of the biventricular (BV) stimulation is essential for the success of cardiac resynchronization therapy (CRT) in patients with cardiac insufficiency and widened QRS complex. 3D modeling allows the simulation of CRT and high frequency (HF) ablation.
Purpose: The aim of the study was to model different pacing and ablation electrodes and to integrate them into a heart model for the static and dynamic simulation of BV stimulation and HF ablation in atrial fibrillation (AF).
Methods: The modeling and simulation was carried out using the electromagnetic simulation software. Five multipolar left ventricular (LV) electrodes, one epicardial LV electrode, four bipolar right atrial (RA) electrodes, two right ventricular (RV) electrodes and one HF ablation catheter were modeled. Different models of electrodes were integrated into a heart rhythm model for the electrical field simulation (fig.1). The simulation of an AV node ablation at CRT was performed with RA, RV and LV electrodes and integrated ablation catheter with an 8 mm gold tip.
Results: The RV and LV stimulation were performed simultaneously at amplitude of 3 V at the LV electrode and 1 V at the RV electrode, each with a pulse width of 0.5 ms. The far-field potentials generated by the BV stimulations were perceived by the RA electrode. The far-field potential at the RA electrode tip was 32.86 mV. A far-field potential of 185.97 mV resulted at a distance of 1 mm from the RA electrode tip. AV node ablation was simulated with an applied power of 5 W at 420 kHz at the distal 8 mm ablation electrode. The temperature at the catheter tip was 103.87 ° C after 5 s ablation time, 44.17 ° C from the catheter tip in the myocardium and 37.61 ° C at a distance of 2 mm. After 10 s, the temperature at the three measuring points described above was 107.33 ° C, 50.87 ° C, 40.05 ° C and after 15 seconds 118.42 ° C, 55.75 ° C and 42.13 ° C.
Conclusions: Virtual heart and electrode models as well as the simulations of electrical fields and temperature profiles allow the static and dynamic simulation of atrial synchronous BV stimulation and HF ablation at AF. The 3D simulation of the electrical field and temperature profile may be used to optimize the CRT and AF ablation.
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.
BiCI users’ sensitivity to interaural phase differences for single- and multi-channel stimulation
(2016)
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.
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.
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.
Introduction: Cardiac resynchronisation therapy (CRT) with atrioventricular (AV) and interventricular (VV) optimized biventricular pacing (BV) is an established therapy for heart failure (HF) patients. The aim of the study was to compare AV and VV delay optimization with cardiac output (CO), cardiac index (CI), contractility index (IC) and acceleration index (ACI) impedance cardiographic (ICG) methods in CRT.
Methods: 15 HF patients (age 66 ± 10 years; 2 females, 13 males) in New York Heart Association (NYHA) 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, CI, IC and ACI (Cardioscreen ®, Medis GmbH, Ilmenau, Germany) at different AV and VV delay BV pacing settings versus right ventricular (RV) pacing one day after implantation of a CRT device.
Results: 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. Optimal VV delay was -12.3 ± 25.9 ms left ventricular before RV pacing. 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), CI from 1.8 ± 0.64 l/min/m² to 2.4 ± 0.78 l/min/m² (p<0.001), IC from 0.028 ± 0.011 1/s to 0.036 ± 0.013 1/s (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 hemodynamic parameters of transthoracic ICG 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.
Introduction: Cardiac resynchronization therapy (CRT) with biventricular (BV) pacing is an established therapy for heart failure (HF) patients with ventricular desynchronization and reduced left ventricular (LV) ejection fraction. The aim of this study was to evaluate electrical ventricular desynchronization with transthoracic and transesophageal signal averaging electrocardiography in HF, to better select patients for CRT.
Methods: 13 HF patients (age 68 ± 10 years; 2 females, 11 males) with New York Heart Association (NYHA) class 2.8 ± 0.5, 28.6 ± 12.6 % LV ejection fraction and 155 ± 24 ms QRS duration (QRSD) were analysed with transthoracic and transesophageal electrocardiogram recording and novel National Intruments LabView 2009 signal averaging software. Esophageal TO Osypka catheter was perorally applied to the esophagus and placed in the position of maximum LV de-flection. The 0.05-Hz high-pass filtered surface electrocardiogram and the 10-Hz high-pass filtered bipolar transesophageal electrocardiogram were recorded with Bard EP-System and 1000-Hz sampling rate.
Results: Transesophageal LV electrogram recording was possible in all HF patients (n=13). Transesophageal interventricular conduction delay (IVCD) was 51 ± 19 ms and measured between the earliest onset of QRS in the 12-channel surface electrocardiogram and the onset of the LV deflection in the transesophageal electrocardiogram. Transesophageal intra-left ventricular delay (LVCD) was 90 ± 16 ms and measured between the onset and offset of the LV deflection in the transesophageal electrocardiogram. QRSD to transesophageal IVCD ratio was 3.43 ± 1.31 ms, QRSD to transesophageal LVCD ratio was 1.75 ± 0.28 ms and QRSD was evaluated between onset and offset of QRS signal in the 12-channel surface electrocardiogram.
Conclusion: Determination of IVCD, LVCD, QRSD-to-IVCD-ratio and QRSD-to-LVCD-ratio by transesophageal LV electrogram recording with LabView 2009 signal averaging technique may be useful parameters of ventricular desynchronisation to improve patient selection for CRT.
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.