An Unusual Case of Non-Reentrant Atrioventricular Nodal Tachycardia

Although uncommonly encountered, dual atrioventricular nodal non-reentrant tachycardia (DAVNNRT) is a well described arrhythmia that can manifest in patients with dual atrioventricular nodal pathways physiology. This arrhythmia is characterized on ECG by a single P wave followed by two conducted QRS complexes, and on intracardiac EGMs by a single atrial electrogram followed by two separate His deflections and ventricular electrograms. Our case demonstrates a rare case of “triple atrioventricular non-reentrant tachycardia” in which a patient was found to have 3 distinct AV nodal pathways and multiple “triple fire responses”, both on surface ECG and intracardiac electrograms.

136 Blood vortices analysis in children with Wolff–Parkinson–White syndrome

Aims Wolff–Parkinson–White syndrome (WPW) is a clinical condition characterized by pre-excitation on electrocardiogram (ECG) and symptoms of arrhythmias. It has been described that premature ventricular activation induces septal wall motion abnormalities and ventricular dyssynchrony, causing detrimental effects on cardiac performance. The new speckle-tracking-based technique, blood speckle imaging (BSI), has been previously used to evaluate blood flow characteristics in normal and dysfunctional hearts in patients with normal atrio-ventricular (AV) conduction. We aimed to study the features of left ventricle blood vortices in patients with WPW and short AV conduction by using BSI. Methods and results Nineteen paediatric patients (age 7 ± 2.9 years) were included in the study: 13 patients with manifest WPW (WPW group) and 6 age and sex -matched controls with normal AV conduction (CTR group). A complete echocardiographic evaluation with 2D, color Doppler, and BSI was performed in all the included patients. BSI was recorded in apical 3-chamber view with a 6S-D probe. Vortices characteristics were analysed during the filling phase of the left ventricle. We focused on the anterior vortex generated by the mitral valve, which persisted longer during the cardiac cycle and is assumed to contribute to optimizing cardiac function. For each child in the WPW group, Arruda criteria were used to esteem accessory pathway localization from a 12-lead surface ECG. All patients in the WPW group manifested the accessory pathway in the septal region. All patients in the CTR group presented one major anterior vortex along the septal wall during the filling phase (Figure A), while in the WPW group, 10 patients out of 13 (P = 0.009) lacked this main anterior vortex, showing instead fragmented vortices (Figure B). Interestingly, the main differences in blood vortices pattern were showed in the last part of filling phase, when blood flow could be affected by premature activation of the septal wall. There were no differences in terms of left ventricle function (WPWg 59.8 ± 4.02% vs. CTRg 59.0 ± 2.5%, P = 0.6) and global longitudinal strain (WPWg −18.6 ± 1.0% vs. CTRg −19.6 ± 3.1%, P = 0.5) between the two groups. 136 Figure A and B Conclusions In our preliminary study, patients with WPW showed a fragmented pattern of diastolic blood vortices that adapted to septal dyssynchrony. We speculate this fragmentation may contribute to impair the performance of the left ventricle.

Towards prevention of re-entrant arrhythmias: Injectable hydrogel electrodes enable direct capture of previously inaccessible cardiac tissues

Re–entrant arrhythmias – the leading cause of sudden cardiac death – are caused by diseased and delayed myocardial conduction. Access to the coronary veins that cross the culprit scarred regions where re–entry originates provides improved pacing to prevent ventricular arrhythmias and circumvent the need for painful defibrillation, risky cardiac ablation, or toxic and often ineffective antiarrhythmic medications. To date, this goal has not been achieved due to the lack of pacing electrodes which are small or focal enough to navigate these tributaries. We have developed an injectable conductive hydrogel that can fill the epicardial coronary veins and their mid–myocardial tributaries. When connected to a standard pacing lead, these injected hydrogels can be converted into flexible electrodes that directly pace the previously inaccessible mid–myocardial tissue. In our two–component system, hydrogel precursor solutions can be injected through a dual lumen catheter in a minimally invasive deployment strategy to provide direct access to the diseased regions with relative precision and ease. Mixing of the two solutions upon injection into the vein activates redox–initiated crosslinking of the gel for rapid in situ cure without an external stimulus. An ex vivo porcine model was used to identify the requisite viscosity and cure rate for gel retention and homogeneity. Ionic species added to the hydrogel precursor solutions conferred conductivity above target myocardium values that was retained after implantation. Successful in vivo deployment demonstrated that the hydrogel electrode filled the anterior interventricular vein with extension into the septal (mid–myocardial) venous tributaries, far deeper than current technologies allow. In addition to successful capture and pacing of the porcine heart, analysis of surface ECG tracings revealed a novel pacing paradigm not observed in traditional single–point pacing: capture of extensive swaths of the native conduction system. This is the first report of an injectable electrode used to successfully pace the mid–myocardium and mimic physiologic conduction. As such, this injectable hydrogel electrode can be deployed to any region affected by prior myocardial infarction and consequent scar tissue to provide a reliable pacing modality that most closely resembles native conduction.

Machine learning-derived electrocardiographic algorithm for the detection of cardiac amyloidosis

BackgroundDiagnosis of cardiac amyloidosis (CA) requires advanced imaging techniques. Typical surface ECG patterns have been described, but their diagnostic abilities are limited.ObjectiveThe aim was to perform a thorough electrophysiological characterisation of patients with CA and derive an easy-to-use tool for diagnosis.MethodsWe applied electrocardiographic imaging (ECGI) to acquire electroanatomical maps in patients with CA and controls. A machine learning approach was then used to decipher the complex data sets obtained and generate a surface ECG-based diagnostic tool.FindingsAreas of low voltage were localised in the basal inferior regions of both ventricles and the remaining right ventricular segments in CA. The earliest epicardial breakthrough of myocardial activation was visualised on the right ventricle. Potential maps revealed an accelerated and diffuse propagation pattern. We correlated the results from ECGI with 12-lead ECG recordings. Ventricular activation correlated best with R-peak timing in leads V1–V3. Epicardial voltage showed a strong positive correlation with R-peak amplitude in the inferior leads II, III and aVF. Respective surface ECG leads showed two characteristic patterns. Ten blinded cardiologists were asked to identify patients with CA by analysing 12-lead ECGs before and after training on the defined ECG patterns. Training led to significant improvements in the detection rate of CA, with an area under the curve of 0.69 before and 0.97 after training.InterpretationUsing a machine learning approach, an ECG-based tool was developed from detailed electroanatomical mapping of patients with CA. The ECG algorithm is simple and has proven helpful to suspect CA without the aid of advanced imaging modalities.

Ex vivo Validation of Noninvasive Epicardial and Endocardial Repolarization Mapping

Background: The detection and localization of electrophysiological substrates currently involve invasive cardiac mapping. Electrocardiographic imaging (ECGI) using the equivalent dipole layer (EDL) method allows the noninvasive estimation of endocardial and epicardial activation and repolarization times (AT and RT), but the RT validation is limited to in silico studies. We aimed to assess the temporal and spatial accuracy of the EDL method in reconstructing the RTs from the surface ECG under physiological circumstances and situations with artificially induced increased repolarization heterogeneity.Methods: In four Langendorff-perfused pig hearts, we simultaneously recorded unipolar electrograms from plunge needles and pseudo-ECGs from a volume-conducting container equipped with 61 electrodes. The RTs were computed from the ECGs during atrial and ventricular pacing and compared with those measured from the local unipolar electrograms. Regional RT prolongation (cooling) or shortening (pinacidil) was achieved by selective perfusion of the left anterior descending artery (LAD) region.Results: The differences between the computed and measured RTs were 19.0 ± 17.8 and 18.6 ± 13.7 ms for atrial and ventricular paced beats, respectively. The region of artificially delayed or shortened repolarization was correctly identified, with minimum/maximum RT roughly in the center of the region in three hearts. In one heart, the reconstructed region was shifted by ~2.5 cm. The total absolute difference between the measured and calculated RTs for all analyzed patterns in selectively perfused hearts (n = 5) was 39.6 ± 27.1 ms.Conclusion: The noninvasive ECG repolarization imaging using the EDL method of atrial and ventricular paced beats allows adequate quantitative reconstruction of regions of altered repolarization.

New Onset of AV- Nodal Reentrant Tachycardia (AVNRT) in the elderly – an uncommon diagnosis?

Background Arrhythmias in elderly patients (>70 years) are common in daily clinical practice. Most frequently, they are based on atrial fibrillation or other atrial tachycardia with an indication for oral anticoagulation and specific antiarrhythmic medications. The electrographic (ECG) documentation related to symptoms is essential before therapy initiation. In case of suspected AVNRT based on surface ECG, an electrophysiological study (EP) with ablation as curative strategy should be planned. Methods We analysed all patients >70 years with AVNRT diagnosed by electrophysiologic (EP) studies between May 2018 and December 2020. Results An EP study for suspected AVNRT was performed in 27 patients >70 years. The diagnosis of AVNRT was confirmed in 20 patients (75%). From all EP- studies with the diagnosis of AVNRT (n=93) in this period, 20 patients (22%) were older than 70 years (mean age 77 years with a range of 70–85 years), 12 were women. In most of the patients, the duration of symptoms was short (3 month). Only 4 patients had symptoms of paroxysmal tachycardia longer than 10 years. Except for 2 patients, all patients had at least one ECG- documentation (12- lead- ECG, Holter- ECG, telemetric ECG and/or in the loop recorder). In 12 patients, a 12- lead- ECG- documentation was available, in 5 patients the tachycardia has been registered in the Holter-ECG and in 1 in a loop recorder. In the 12- lead- ECG before ablation in sinus rhythm the PQ interval was with 196 (120- 300) ms in the upper range. In 16/ 20 patients was during the EP- study a sustained AVNRT (CL 410, 314- 538 ms) inducible. In the others, up to 3 typical AV- nodal- echo beats were induced in the EP- study. A slow pathway ablation/ modification was performed in all patients in typical position. In 2 patients, the implantation of a dual- chamber- pacemaker was necessary due to intermittent high- degree AV-nodal-block during the same hospital stay. In both patients, a first degree AV-block with PQ- interval of 250 and 300 ms was pre-existing. Discussion Especially for the elderly patients with new onset of clinical symptoms of arrhythmia, clinical anamnesis including an ECG- documentation is required for planning the therapeutic strategy. A borderline long PQ- interval as sign of an age- dependent fibrosis in the AV- node and, therefore, altered conduction properties in the AV node can be a cause of AVNRT in these older patients. In patients with pre-existing long PQ- interval (>250 ms), the risk of pacemaker implantation after successful ablation is higher. In this group of patients, medical therapeutic options are limited and often associated with the need of pacemaker implantation. FUNDunding Acknowledgement Type of funding sources: None.

A machine learning-derived electrocardiographic algorithm for the detection of cardiac amyloidosis

Background The diagnosis of cardiac amyloidosis (CA) requires advanced imaging techniques. Typical surface ECG patterns have been described, but their diagnostic value is limited. Purpose The aim of this study was to perform a comprehensive electrophysiological characterization in CA patients and to develop a robust, easy-to-use diagnostic tool. Methods First, we applied electrocardiographic imaging (ECGI) to generate detailed electroanatomical maps in CA patients and controls. Then, a machine learning approach was used to generate a surface ECG-based diagnostic algorithm from the complex dataset. Results Areas of low voltage were localized in the basal inferior regions of both ventricles and the remaining right ventricular segments in CA. The earliest epicardial breakthrough of myocardial activation was visualized in the right ventricle. Potential maps showed an accelerated and diffuse propagation pattern. We correlated the results from ECGI with 12-lead ECG recordings. Ventricular activation correlated best with R-peak timing in leads V1 to V3. Epicardial voltage showed a strong positive correlation with R-peak amplitude in inferior leads II, III, aVF. Ten blinded cardiologists were then asked to identify CA patients by analyzing 12-lead ECGs before and after training for the defined ECG patterns. Training resulted in significant improvements in the detection rate of CA with an AUC of 0.69 before and 0.97 after training (Figure). Conclusion Using a machine learning approach, a robust ECG-based tool was developed to detect CA from detailed electroanatomical mapping of CA patients. The developed tool proved to be a simple and reliable diagnostic tool to suspect CA without the aid of advanced imaging modalities. FUNDunding Acknowledgement Type of funding sources: None.

Differentiating the origin of outflow tract premature ventricular complexes using the QRS-right ventricular apex interval

Background For localization of outflow tract Premature ventricular complexes (PVCs) many ECG criteria have been proposed, however in some cases it is difficult to accurately localize the origin of PVCs using the surface ECG. Objective This study aims to study the relation between QRS-right ventricular apex interval and the origin of the outflow tract PVCs. Patients and Methods The study included 30 patients (27 female, age 37.20 ± 7.87, RVOT origin 18) referred for PVCs ablation and we measured the interval from the onset of the earliest QRS complex of premature ventricular contractions (PVCs) to the distal right ventricular apical signal, (the QRS-RVA interval) and correlated this interval with origin of outflow tract PVCs as identified by the successful ablation during the procedure. Results Compared to PVCs originating from RVOT, the QRS-RVA interval was significantly longer in PVCs originating from LVOT (67.33±7.56 for LVOT PVCs vs. 37.11±4.34 for RVOT PVCs, p < 0.001). Receiver operating characteristic (ROC) analysis showed that a QRSRVA interval ≥47 ms has a sensitivity, specificity, positive and negative predictive values of 100%, 100%, 100%, 100% respectively, for prediction of an LVOT origin of PVCs Conclusion The QRS-RVA interval is a simple and accurate criterion for differentiating the origin of outflow tract arrhythmia during electrophysiology study, A QRS-RVA interval ≥47 ms suggests an LVOT origin of PVCs.

А new electrocardiographic criterion in diagnosis right ventricular myocardial infarction

The aim of this study is to identify the features of ST-changes in 12-leads surface ECG, which help to diagnose the right ventricular involvement in inferior myocardial infarction. The study included 145 patients with inferior myocardial infarction, the right ventricular infarction (RVI) was detected by echocardiography in 62 (42.8%) patients. ST segment depression in lead aVL was deeper than in lead V3 in 93.5% of patients with RVI. This feature is revealed in 4.9% patients with inferior myocardial infarction without RVI only. The sensitivity of this criterion for diagnosis RVI is 93.5%, the specificity is 95.2%, the predictive value of positive and negative results make up 93.5 and 95.2%.