Methodology for detection of paroxysmal atrial fibrillation based on P-Wave, HRV and QR electrical alternans features

The detection of Paroxysmal Atrial Fibrillation (PAF) is a fairly complex process performed manually by cardiologists or electrophysiologists by reading an electrocardiogram (ECG). Currently, computational techniques for automatic detection based on fast Fourier transform (FFT), Bayes optimal classifier (BOC), k-nearest neighbors (K-NNs), and artificial neural network (ANN) have been proposed. In this study, six features were obtained based on the morphology of the P-Wave, the QRS complex and the heart rate variability (HRV) of the ECG. The performance of this methodology was validated using clinical ECG signals from the Physionet arrhythmia database MIT-BIH. A feedforward neural network was used to detect the presence of PAF reaching a general accuracy of 97.4%. The results obtained show that the inclusion of the information of the P-Wave, HRV and QR Electrical alternans increases the accuracy to identify the PAF event compared to other works that use the information of only one or at most two of them.

ICD-Electrode-Perforation of the Right Ventricle to the Pericardium with and without Pericardial Effusion

Two cases are described of iatrogenic traumatic perforation of an ICD electrode through the myocardium in the right ventricle and to the pericardium. The diagnostic gold standard gated CT was not necessary in either case. In the first case the lead insertion was difficult, time-consuming, and complicated by the PostCardiac Injury Syndrome and a slowly accumulating hemorrhagic pericardial effusion causing cardiac tamponade, diagnosed by the clinical picture, elevated CRP, ECG with low voltage and electrical alternans, chest X-ray revealing enlarged cardiac silhouette and echocardiography a large effusion, treated with pericardiocentesis and drainage. In the other case there was painful pericardial irritation and extracardiac pacing and ICD failure with loss of capture, no diagnostic changes in ECG, chest X-ray, and echocardiography; diagnosed by fluoroscopy during replacement at the lead, which went without complications and without pericardial effusion.

Mechanistic insights into ventricular arrhythmogenesis of hydroxychloroquine and azithromycin for the treatment of COVID-19

ABSTRACTAimsWe investigate mechanisms for potential pro-arrhythmic effects of hydroxychloroquine (HCQ) alone, or combined with azithromycin (AZM), in Covid-19 management supplementing the limited available experimental cardiac safety data.MethodsWe integrated patch-clamp studies utilizing In Vitro ProArrhythmia Assay (CiPA) Schema IC50 paradigms, molecular modelling, cardiac multi-electrode array and voltage (RH237) mapping, ECG studies, and Ca2+ (Rhod-2 AM) mapping in isolated Langendorff-perfused guinea-pig hearts with human in-silico ion current modelling.ResultsHCQ blocked IKr and IK1 with IC50s (10±0.6 and 34±5.0 μM) within clinical therapeutic ranges, INa and ICaL at higher IC50s, leaving Ito and IKs unaffected. AZM produced minor inhibition of INa, ICaL, IKs, and IKr,, sparing IK1 and Ito. HCQ+AZM combined inhibited IKr and IK1 with IC50s of 7.7±0.8 μM and 30.4±3.0 μM, sparing INa, ICaL and Ito. Molecular modelling confirmed potential HCQ binding to hERG. HCQ slowed heart rate and ventricular conduction. It prolonged PR, QRS and QT intervals, and caused prolonged, more heterogeneous, action potential durations and intracellular Ca2+ transients. These effects were accentuated with combined HCQ+AZM treatment, which then elicited electrical alternans, re-entrant circuits and wave break. Modelling studies attributed these to integrated HCQ and AZM actions reducing IKr and IK1, thence altering cell Ca2+ homeostasis.ConclusionsCombined HCQ+AZM treatment exerts pro-arrhythmic ventricular events by synergetically inhibiting IKr, IKs with resulting effects on cellular Ca2+ signalling, and action potential propagation and duration. These findings provide an electrophysiological basis for recent FDA cardiac safety guidelines cautioning against combining HCQ/AZM when treating Covid-19.