Bipolar ECG Research Articles

Precordial electrocardiographic recording and QT measurement from a novel wearable ring device

BackgroundThe availability of portable and wearable electrocardiography devices has increased secondary to technological development. Single-lead ECG recordings have been shown to reliably detect and characterize cardiac rhythms such as atrial fibrillation. Acquisition of precordial electrodes for full 12-lead ECG reconstruction from bipolar recordings is complicated by the absence of a body ground / Wilson central terminal electrode, however the extent of difference between standard precordial lead and those from a wearable bipolar ECG recorder has not been characterized. ObjectiveThis study characterizes precordial ECG lead set from sequential bipolar recordings from an ECG ring wearable device. MethodsIn 70 patients wearing an ECG device on their right finger, sequential precordial leads (CR1-CR6) were obtained along with chest electrodes (V1-V6). During acquisition of the modified precordial lead CR6 a full standardized 12 lead ECG capture was obtained.Using automated analysis software, signal quality was assessed, and the correlation values between the ring-derived ECG precordial leads and standard ECG leads were compared with QRS duration, QT width, and RR interval measurement. ResultsThere is high concordance in the morphology of precordial ECG leads obtained in a standard fashion and those recorded through an ECG ring. Morphologic alignment improved with increasing laterality of the precordial lead with chest to right arm ring recording (CR5, CR6) compared with anterior chest leads to right arm (CR1, CR2). Segmental measurements of QRS duration and QT segment were well aligned and of high correlation. ConclusionWearable ring based electrocardiographic technology is capable of high fidelity recording of precordial leads for non-simultaneous reconstruction of complete ECG sets. These correlate highly with surface-obtained QRS and QT duration measurement, which has significant implications for clinical applications. Uninterpretable tracings were primarily due to electrode noise from poor electrode contact.

Abstract 17557: Single Limb-Lead Electrocardiogram Accuracy in Screening for Ventricular Pre-Excitation

Introduction: Consumer devices capable of recording bipolar ECGs have been investigated and validated for atrial fibrillation detection and QT interval monitoring. Application of the technology to other electrical abnormalities like Wolff-Parkinson-White (WPW) is limited but could enhance the ability to screen for risk of cardiac arrhythmias before they occur. Aims: 1. Determine how frontal lead ECGs perform in identification of ventricular pre-excitation (VPE).2. Determine which of the standard 3 bipolar leads perform best for this detection.3. Quantify the impact of training of the interpreter on identification of VPE with single lead tracings. Methods: Standard 12-lead ECGs were obtained from 20 patients before and after successful radiofrequency ablation of a single manifest accessory pathway. 3-second tracings were abstracted from leads I, II, and III from each ECG and were presented in random order to interpreters of varying experience and specialization who were asked to evaluate whether the tracing showed VPE. Results were tabulated to determine the accuracy of VPE identification. Descriptive statistics of the performance of each lead (alone and in combinations) and interpreter type were calculated. Results: A total of 52 respondents interpreted 5108 ECG tracings. Some respondents did not read all tracings and there were unequal numbers of respondents in the different interpreter categories. The Table below depicts the performance of each lead and respondent subgroups. Conclusions: VPE can be identified with reasonable accuracy using a single limb-lead ECG tracing, with lead I performing better than leads II and III. Addition of lead II or III improved accuracy by 5% only. Most consumer devices record lead I, suggesting that they could be used to screen for WPW. Interpreter specialization correlated more with accuracy than training status.

ELECTRICAL ACTIVITY OF THE HUMAN HEART DURING THE PERIOD OF VENTRICULAR DEPOLARIZATION UNDER ACUTE NORMOBARIC HYPOXIA

Background. The effect of acute hypoxia on the human heart leads to deterioration of the heart function, this is reflected in an increase of the heterogeneity of the depolarization process, which is difficult to reveal when using a traditional ECG.
 Purpose. To investigate the electrical activity of the heart during the ventricular depolarization on the thorax surface under the exposure of acute normobaric hypoxia using multichannel ECG mapping.
 Material and methods. The electrical activity of the heart in apparently healthy young men (20±1 years) was studied during ventricular depolarization under exposure of acute normobaric hypoxia using cardioelectrotopography. Unipolar ECGs were recorded from 64 electrodes on the surface of the chest, simultaneously with bipolar ECGs in limb leads and the amplitudes of R and S waves from the surface electrodes localized in positions V1 and V5 of the traditional ECG were evaluated.
 Results. It was revealed that during hypoxia, in comparison with the initial state, the pattern of distribution and the spatio-temporal dynamics of positive and negative cardiac potentials reflecting the sequence of myocardial activation on the torso surface did not change significantly and were typical for the period of ventricular depolarization of the healthy person. A decrease in the amplitudes of the maximum extrema of cardiac electric potentials, the amplitudes of the SV1 and RV5 waves at hypoxic exposure was revealed: the amplitude of the maximum decreased from 1.88±0.58 mV in the initial state to 1.83±0.55 mV at hypoxia, the minimum – from -2.08±0.76 mV to -1.85±0.73 mV, the SV1 wave from -1.28±0.25 mV to -1.17±0.18 mV, RV5 wave from 1.21±0.25 mV to 1.05±0.29 mV, respectively, while the duration of ventricular depolarization did not change statistically significantly.
 Conclusion. Under hypoxic exposure, the examined persons showed a significant decrease in the amplitudes of the maximum extrema of the electric field of the heart, a direct correlation between changes in the amplitudes of the positive extremum and the RV5 wave, with practically unchanged duration of ventricular depolarization and dynamics of the distribution of cardioelectric potentials.

A finite element model of the embryonic zebrafish heart electrophysiology

Background and objectiveIn the last 30 years, a growing interest has involved the study of zebrafish thanks to its physiological characteristics similar to those of humans. The aim of the following work is to create an electrophysiological computational model of the zebrafish heart and lay the foundation for the development of an in-silico model of the zebrafish heart that will allow to study the correlation between pathologies and drug administration with the main electrophysiological parameters as the ECG signal. MethodsThe model considers a whole body and the two chambers of three days post fertilization (3 dpf) zebrafish. A four-variable phenomenological action potential model describes the action potential of different heart regions. Tissue conductivity was calibrated to reproduce the experimentally described activation sequence. ResultsThe model is able to correctly reproduce the activation sequence and times found in literature, with activation of the atrium and ventricle that correspond to 36 and 59 ms, respectively, and a delay of 14 ms caused by the presence of the atrioventricular band (AV band). Moreover, the obtained in-silico ECG reflects the main characteristics of the zebrafish ECG in good agreement with experimental records, a P-wave with a duration of approximately the total atrial activation, followed by a QRS complex of approximately 109 ms corresponding to ventricle activation. ConclusionsThe model allows the assessment of the main electrophysiological parameters in terms of activation sequence and timing, reproducing monopolar and bipolar ECG signals in line with experimental data. Coupling the proposed model with an electrophysiological detailed action potential model of zebrafish will represent a significant breakthrough toward the development of an in-silico zebrafish heart.

PO-639-01 ENHANCED P WAVE RECOGNITION THROUGH RA-XIPHOIDAL LEAD BY HUAWEI WATCH ECG RECORDING

ECG recording through the Huawei watch’s (GT2 pro ECG edition, Huawei Technology Co., Ltd, Shenzhen, PR China) back electrode on the left wrist and the right index finger on the crown simulates the Einthoven’s bipolar ECG lead I (Huawei Watch Lead I ECG, HWIG), which is not a good trace for arrhythmia diagnosis due to its indistinct P wave in some cases. Therefore, additional smartwatch leads such as right arm-left leg lead, right arm-precordial leads are required to get more accurate ECG information.

Atrial fibrillatory rate as predictor of recurrence of atrial fibrillation in horses treated medically or with electrical cardioversion.

The recurrence rate of atrial fibrillation (AF) in horses after cardioversion to sinus rhythm (SR) is relatively high. Atrial fibrillatory rate (AFR) derived from surface ECG is considered a biomarker for electrical remodelling and could potentially be used for the prediction of successful AF cardioversion and AF recurrence. Evaluate if AFR was associated with successful treatment and could predict AF recurrence in horses. Retrospective multicentre study. Electrocardiograms (ECG) from horses with persistent AF admitted for cardioversion with either medical treatment (quinidine) or transvenous electrical cardioversion (TVEC) were included. Bipolar surface ECG recordings were analysed by spatiotemporal cancellation of QRST complexes and calculation of AFR from the remaining atrial signal. Kaplan-Meier survival curve and Cox regression analyses were performed to assess the relationship between AFR and the risk of AF recurrence. Of the 195 horses included, 74 received quinidine treatment and 121 were treated with TVEC. Ten horses did not cardiovert to SR after quinidine treatment and AFR was higher in these, compared with the horses that successfully cardioverted to SR (median [interquartile range]), (383 [367-422] vs 351 [332-389] fibrillations per minute (fpm), P<.01). Within the first 180days following AF cardioversion, 12% of the quinidine and 34% of TVEC horses had AF recurrence. For the horses successfully cardioverted with TVEC, AFR above 380 fpm was significantly associated with AF recurrence (hazard ratio=2.4, 95% confidence interval 1.2-4.8, P=.01). The treatment groups were different and not randomly allocated, therefore the two treatments cannot be compared. Medical records and the follow-up strategy varied between the centres. High AFR is associated with failure of quinidine cardioversion and AF recurrence after successful TVEC. As a noninvasive marker that can be retrieved from surface ECG, AFR can be clinically useful in predicting the probability of responding to quinidine treatment as well as maintaining SR after electrical cardioversion.

Multichannel electrocardiograms obtained by a smartwatch for the diagnosis of acute coronary syndromes: the SMARTAMI TRIAL

Abstract Background Smartwatches are increasingly popular and used for digital health information. A new smart watch introduced an integrated ECG tool, which allows recording a single-lead ECG that has been used for atrial fibrillation detection. The aim of the present study was to prospectively investigate the feasibility and the accuracy of the Apple Watch in patients admitted in the CCU with the diagnosis of Acute Coronary Syndrome compared with a standard 12-lead ECG. Methods A commercially available smart watch series 4 was used and the posterior sensor of the watch was positioned in different standardized body positions to obtain nine bipolar ECGs (corresponding to Einthoven leads I, II and III and Precordial leads V1-V6) that were compared with a simultaneous standard 12-lead ECG. One hundred subjects were included in the study. Fifty-five patients had a STEMI, twenty-seven patients had an NSTEMI all treated with percutaneous coronary revascularization. Eighteen age-matched subjects were included as controls. Results A very good agreement was found between Smartwatch ECG and Standard ECG for the identification of normal ECG, ST segment elevation and NSTE alterations (Cohen's kappa 0.90 [95% CI 0.78 to 1], 0.88 [95% CI 0.78 to 0,97], 0.85 [95% CI 0.74 to 0.96]), respectively. The sensitivity and specificity of Smartwatch ECG for the diagnosis of normal ECG were 84% (95% CI 60 to 97) and 100% (95% CI 95 to 100), STE deviation were 93% (95% CI 82 to 99) and 95% (95% CI 85 to 99), NSTE ECG alterations were 94% (95% CI 81 to 99) and 92% (95% CI 83 to 97), respectively. No significant differences between Smartwatch ECG and Standard ECG for the amplitude of ST changes were reported for each lead (see Figure). Conclusions The Smart Ami Trial demonstrated a very good agreement between the Smartwatch ECG and Standard ECG for the identification of ST-segment elevation and ST depression in patients with acute coronary syndromes opening the possibility of using this tool when a standard ECG is not available. Figure 1 Funding Acknowledgement Type of funding source: None

Comparison between smartphone electrocardiography and standard three-lead base apex electrocardiography in healthy horses

BackgroundCardiac arrhythmias are commonly auscultated during routine physical examinations in horses and determining the underlying electrical abnormality using an ECG is important. The most commonly used device is a three-lead...

Arm-ECG Wireless Sensor System for Wearable Long-Term Surveillance of Heart Arrhythmias

This article presents the devising, development, prototyping and assessment of a wearable arm-ECG sensor system (WAMECG1) for long-term non-invasive heart rhythm monitoring, and functionalities for acquiring, storing, visualizing and transmitting high-quality far-field electrocardiographic signals. The system integrates the main building blocks present in a typical ECG monitoring device such as the skin surface electrodes, front-end amplifiers, analog and digital signal conditioning filters, flash memory and wireless communication capability. These are integrated into a comfortable, easy to wear, and ergonomically designed arm-band ECG sensor system which can acquire a bipolar ECG signal from the upper arm of the user over a period of 72 h. The small-amplitude bipolar arm-ECG signal is sensed by a reusable, long-lasting, Ag–AgCl based dry electrode pair, then digitized using a programmable sampling rate in the range of 125 to 500 Hz and transmitted via Wi-Fi. The prototype comparative performance assessment results showed a cross-correlation value of 99.7% and an error of less than 0.75% when compared to a reference high-resolution medical-grade ECG system. Also, the quality of the recorded far-field bipolar arm-ECG signal was validated in a pilot trial with volunteer subjects from within the research team, by wearing the prototype device while: (a) resting in a chair; and (b) doing minor physical activities. The R-peak detection average sensibilities were 99.66% and 94.64%, while the positive predictive values achieved 99.1% and 92.68%, respectively. Without using any additional algorithm for signal enhancement, the average signal-to-noise ratio (SNR) values were 21.71 and 18.25 for physical activity conditions (a) and (b) respectively. Therefore, the performance assessment results suggest that the wearable arm-band prototype device is a suitable, self-contained, unobtrusive platform for comfortable cardiac electrical activity and heart rhythm logging and monitoring.

Single-Lead ECG Recordings Including Einthoven and Wilson Leads by a Smartwatch: A New Era of Patient Directed Early ECG Differential Diagnosis of Cardiac Diseases?

Background: Smartwatches that are able to record a bipolar ECG and Einthoven leads were recently described. Nevertheless, for detection of ischemia or other cardiac diseases more leads are required, especially Wilson’s chest leads. Objectives: Feasibility study of six single-lead smartwatch (Apple Watch Series 4) ECG recordings including Einthoven (I, II, III) and Wilson-like pseudo-unipolar chest leads (Wr, Wm, Wl). Methods: In 50 healthy subjects (16 males; age: 36 ± 11 years, mean ± SD) without known cardiac disorders, a standard 12-lead ECG and a six single-lead ECG using an Apple Watch Series 4 were performed under resting conditions. Recording of Einthoven I was performed with the watch on the left wrist and the right index finger on the crown, Einthoven II was recorded with the watch on the left lower abdomen and the right index finger on the crown, Einthoven III was recorded with the watch on the left lower abdomen and the left index finger on the crown. Wilson-like chest leads were recorded corresponding to the locations of V1 (Wr), V4 (Wm) and V6 (Wl) in the standard 12-lead ECG. Wr was recorded in the fourth intercostal space right parasternal, Wm was recorded in the fifth intercostal space on the midclavicular line, and Wl was recorded in the fifth intercostal space in left midaxillary line. For all Wilson-like chest lead recordings, the smartwatch was placed on the described three locations on the chest, the right index finger was placed on the crown and the left hand encompassed the right wrist. Both hands and forearms also had contact to the chest. Three experienced cardiologists were independently asked to allocate three bipolar limb smartwatch ECGs to Einthoven I–III leads, and three smartwatch Wilson-like chest ECGs (Wr, Wm, Wl) to V1, V4 and V6 in the standard 12-lead ECG for each subject. Results: All 300 smartwatch ECGs showed a signal quality useable for diagnostics with 281 ECGs of good signal quality (143 limb lead ECGs (95%), 138 chest lead ECGs (92%). Nineteen ECGs had a moderate signal quality (7 limb lead ECGs (5%), 12 chest lead ECGs (8%)). One-hundred percent of all Einthoven and 92% of all Wilson-like smartwatch ECGs were allocated correctly to corresponding leads from 12-lead ECG. Forty-six subjects (92%) were assigned correctly by all cardiologists. Allocation errors were due to similar morphologies and amplitudes in at least two of the three recorded Wilson-like leads. Despite recording with a bipolar smartwatch device, morphology of all six leads was identical to standard 12-lead ECG. In two patients with acute anterior myocardial infarction, all three cardiologists recognized the ST-elevations in Wilson-like leads and assumed an occluded left anterior descending coronary artery correctly. Conclusion: Consecutive recording of six single-lead ECGs including Einthoven and Wilson-like leads by a smartwatch is feasible with good ECG signal quality. Thus, this simulated six-lead smartwatch ECG may be useable for the detection of cardiac diseases necessitating more than one ECG lead like myocardial ischemia or more complex cardia arrhythmias.

Recording of Bipolar Multichannel ECGs by a Smartwatch: Modern ECG Diagnostic 100 Years after Einthoven.

Aims: Feasibility study of accurate three lead ECG recording (Einthoven I, II and III) using an Apple Watch Series 4. Methods: In 50 healthy subjects (18 male; age: 40 ± 12 years) without known cardiac disorders, a 12-lead ECG and three bipolar ECGs, corresponding to Einthoven leads I, II and III were recorded using an Apple Watch Series 4. Einthoven I was recorded with the watch on the left wrist and the right index finger on the crown, Einthoven II with the watch on the left lower abdomen and the right index finger on the crown, Einthoven III with the watch on the left lower abdomen and the left index finger on the crown. Four experienced cardiologists were independently asked to assign the watch ECGs to Einthoven leads from 12-lead ECG for each subject. Results: All watch ECGs showed an adequate signal quality with 134 ECGs of good (89%) and 16 of moderate signal quality (11%). Ninety-one percent of all watch ECGs were assigned correctly to corresponding leads from 12-lead ECG. Thirty-nine subjects (78%) were assigned correctly by all cardiologists. All assignment errors occurred in patients with similar morphologies and amplitudes in at least two of the three recorded leads. Erroneous assignment of all watch ECGs to leads from standard ECG occurred in no patient. Conclusion: Recording of Einthoven leads I-III by a smartwatch is accurate and highly comparable to standard ECG. This might contribute to an earlier detection of cardiac disorders, which are associated with repolarization abnormalities or arrhythmias.

Standard ECG lead I prospective estimation study from far-field bipolar leads on the left upper arm: A neural network approach

In this study, the feasibility of interpreting heart rhythms from far-field bipolar ECG arm-band lead recordings on the left-upper-arm (LUA), is evaluated in a clinical multichannel arm-ECG mapping database (N = 153 subjects) for the prospective development of long-term heart rhythm monitoring from comfortable arm wearable devices. A preliminary multivariable linear regression analysis on ECG chest Lead I from 10 selected far-field bipolar leads along the left arm, indicated that 3 of them in the LUA were relevant and worth evaluating in more detail from a heart rhythm information perspective.To derive a good and effective estimation process, a time series non-linear regression point estimator, using an artificial neural network with 2 lags was investigated, showing a correlation coefficient of up to 0.969 for a single subject. Then, a vector approach was adopted for the whole LUA database, aiming to develop a subject independent estimation process of the P-QRS-T waveform interval and its heart rhythm attributes in the standard chest Lead I. In the same study, the first 96 coefficients, of the Discrete Cosine Transform on the P-QRS-T interval were used as a means for reducing the dimensionality of the input space, with a loss of just 0.1% in power, and reducing the dimensionality to just 5% of the original size. The trained ANN for ECG Lead I estimation from one upper arm Lead-1 showed a correlation coefficient above 80% on a beat-to-beat basis, an improvement on all but 1.34% of the beats estimated for a typical train/test partition of the LUA database. The non-triviality of the results was tested with random and intentional true negatives. Information theory analytics revealed that there is an estimated information of 1.6 bits/beat between LUA armband bipolar leads and the standard Lead I.

Diagnostic accuracy of multi-lead ECGs obtained using a pocket-sized bipolar handheld event recorder

BackgroundHandheld ECG event recorders are useful for rhythm monitoring but only record a single lead, which may limit interpretation. We sought to investigate if a multi-lead ECG may be reconstituted using this device, and aimed to evaluate diagnostic accuracy. MethodsA commercially-available handheld bipolar ECG event recorder was used to reconstruct a 9-lead ECG (leads I, II and III, V1–6). Tracings were analyzed independently by a cardiologist and a fellow. ResultsA total of 52 patients were evaluated. Accuracy was excellent (85–98%) for identifying atrial fibrillation, atrioventricular block, bundle branch block and left ventricular hypertrophy, but lower (77–88%) for ST-segment changes and prolonged QTc. ConclusionsA 9-lead ECG can be reconstituted using a handheld single-lead ECG event recorder, and provides good diagnostic accuracy for common findings.

Electrical interventricular delay and left ventricular delay in right ventricular pacemaker pacing before upgrading to cardiac resynchronization therapy

Abstract Cardiac resynchronization therapy with biventricular pacing is an established therapy for heart failure patients with sinus rhythm, reduced left ventricular ejection fraction and electrical ventricular desynchronization. The aim of the study was to evaluate electrical interventricular delay and left ventricular delay in right ventricular pacemaker pacing before upgrading to cardiac resynchronization therapy. Heart failure patients with right ventricular pacing, DDD pacemaker, DDD defibrillator and 24.5 ± 4.9 % left ventricular ejection fraction were measured by surface ECG and transesophageal bipolar left ventricular ECG before upgrading to cardiac resynchronization therapy. Interventricular and intraventricular desynchronization in right ventricular pacemaker pacing were 228.2 ± 44.8ms QRS duration, 86.5 ± 32.8ms interventricular delay and 94.4 ± 23.8ms left ventricular delay. Cardiac resynchronization therapy was optimized by impedance cardiography. Transesophageal electrical interventricular delay and left ventricular delay in right ventricular pacemaker pacing may be additional useful ventricular desynchronization parameters to improve patient selection for upgrading right ventricular pacemaker pacing to cardiac resynchronization therapy.

P1526Interventricular delay and left ventricular delay in right ventricular pacemaker pacing before upgrading to biventricular pacing

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.

Wireless sensor node for non-invasive high precision electrocardiographic signal acquisition based on a multi-ring electrode

Abstract Concentric ring electrodes (CRE) have been proposed for sensing bioelectrical activity with high spatial resolution. Computational studies have revealed that the CRE dimensions are closely related to the electric dipole depth they can sense, but further experimental confirmation is needed. We aimed to develop and test a wireless multichannel ECG recording system based on a new flexible multi-ring electrode and to check the influence of CRE dimensions on the acquired signals. The system provided high-precision ECG signals by a simple procedure. The bipolar concentric ECG signal amplitude and SNR increase with the CRE’s outer ring dimension. Differences in the signal morphologies, associated with different sensitivities to the location of the active dipoles, were also obtained in the case of diameters smaller than 34 mm. A system with several wireless sensor nodes developed could be easily used by clinical staff for non-invasive cardiac monitoring and diagnosis with high spatial and temporal resolution.

Left cardiac atrioventricular delay and inter-ventricular delay in cardiac resynchronization therapy responder and non-responder

Abstract Cardiac resynchronization therapy is an established therapy for heart failure patients. The aim of the study was to evaluate electrical left cardiac atrioventricular delay and interventricular desynchronization in sinus rhythm cardiac resynchronization therapy responder and non-responder. Cardiac electrical desynchronization were measured by surface ECG and focused transesophageal bipolar left atrial and left ventricular ECG before implantation of cardiac resynchronization therapy defibrillators. Preoperative electrical cardiac desynchronization was 195.7 ± 46.7 ms left cardiac atrioventricular delay and 74.8 ± 24.5 ms interventricular delay in cardiac resynchronization therapy responder. Cardiac resynchronization therapy responder New York Heart Association class improved during long term biventricular pacing. Transesophageal left cardiac atrioventricular delay and interventricular delay may be additional useful parameters to improve patient selection for cardiac resynchronization therapy.

Electrocardiogram reconstruction from high resolution voltage optical mapping.

Electrocardiogram recordings during opucal mapping experiments in heart tissue are commonly used tu monitor the health of the preparation and to obtain dominant frequencies during arrhythmic and defibrillatory studies. However the use of ECG reconstructed from optical mapping is seldom used and to date it has not been strictly validated. In this manuscript we present the first detailed validation and comparison of Optical Mapping ECG, or OM-ECG, with standard ECG recordings by calculating the electrostatic potential in space as a function of the voltage measured optically and describe the different approximations that can be used to obtain unipolar or bipolar ECG recordings. We found that in small/medium hearts, such as rabbits, leads that are aligned apex to base only require activation recording from one surface (anterior or posterior) for the OM-ECG to match the ECG while leads aligned left to right may require both an anterior and posterior optical mapping recording. The discrepancy between leads is due to symmetries in the ventricular activations. In the case of ischemic hearts where activations even-out more, the match between the OM-ECG and standard ECG may require only one surface recording for both left-right and base-apex leads. We believe that this methodology has two main and direct applications in the study of cardiac dynamics. The first is during studies of defibrillation where information after the shock may be crucial in the development of new strategies, OM-ECGs do not suffer the current artifacts of standard ECGs during shocks and can be calculated during the entire activation. We present examples in rabbit ventricles where even low amplitude pacing artifacts are captured by the ECG but do not appear in the OM-ECG. The second use of this technique is for reconstructions of intramural dynamics in larger hearts where differences between the ECG and OM-ECG obtained from anterior and posterior recordings can be used to derive the intramural activation.

19-01: Electrical interventricular delay to left ventricular delay ratio in atrial fibrillation cardiac resynchronization therapy responder and non-responder

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.

Towards the clinical use of concentric electrodes in ECG recordings: influence of ring dimensions and electrode position

To overcome the limited spatial resolution of standard 12-lead ECG recordings, concentric ring electrodes (CRE) have been proposed to provide valuable data for the diagnosis of a wide range of cardiac abnormalities, including infarction and arrhythmia. Although theoretical studies indicate that the dimensions of the CRE regulate the depth of the electric dipoles sensed by these electrodes, this has not been experimentally confirmed. The aim of this work was to analyze the influence of CRE dimensions and position of a wireless multi-CRE sensor node on the cardiac signal recorded. For this, four wireless multichannel ECG recording nodes based on flexible multi-ring electrodes were placed at positions CMV1 (position comparable to V1), CMV2, CMV4R and CMV5; each node providing three bipolar concentric ECG signals (BC-ECG). Standard 12-lead ECG and 12 BC-ECG signals were recorded in 29 volunteers. The results revealed that a ring with an outer diameter of 33.5 mm achieves a balance between the ease-of-use and spatial resolution of smaller electrodes and improved detectability and higher amplitudes of signals from larger ring electrodes. Although a standard 12-lead ECG outperforms BC-ECC recordings in detectability of cardiac waves, if the relative amplitude of the wave is also considered, BC-ECG at CMV1 proved superior at picking up atrial activity. In fact, in most of the BC-ECG signals picked up at CMV1, P1 and P2 atrial activity waves were more clearly identified than in simultaneous 12-Lead ECG signals. Likewise, BC-ECG signals revealed higher spatial resolution in detecting anomalous electrical activity in local regions, such as impaired intraventricular driving, or atrioventricular blocks. Finally, the wireless multi-CRE sensor node provides enhanced comfort and handling to both patient and clinician over wired systems.