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Heart rate variability, which is the fluctuation of the R-R interval (RRI) in electrocardiograms (ECG), has been widely adopted for autonomous evaluation. Since the HRV features that are extracted from RRI data easily fluctuate when arrhythmia occurs, RRI data with arrhythmia need to be modified appropriately before HRV analysis. In this study, we consider two types of extrasystoles-premature ventricular contraction (PVC) and premature atrial contraction (PAC)-which are types of extrasystoles that occur every day, even in healthy persons who have no cardiovascular diseases. A unified framework for ectopic RRI detection and a modification algorithm that utilizes an autoencoder (AE) type of neural network is proposed. The proposed framework consists of extrasystole occurrence detection from the RRI data and modification, whose targets are PVC and PAC. The RRI data are monitored by means of the AE in real time in the detection phase, and a denoising autoencoder (DAE) modifies the ectopic RRI caused by the detected extrasystole. These are referred to as AE-based extrasystole detection (AED) and DAE-based extrasystole modification (DAEM), respectively. The proposed framework was applied to real RRI data with PVC and PAC. The result showed that AED achieved a sensitivity of 93% and a false positive rate of 0.08 times per hour. The root mean squared error of the modified RRI decreased to 31% in PVC and 73% in PAC from the original RRI data by DAEM. In addition, the proposed framework was validated through application to a clinical epileptic seizure problem, which showed that it correctly suppressed the false positives caused by PVC. Thus, the proposed framework can contribute to realizing accurate HRV-based health monitoring and medical sensing systems.

Background: Increasing utilization of long-term outpatient ambulatory electrocardiographic (ECG) monitoring continues to drive the need for improved ECG interpretation algorithms., Objective: The purpose of this study was to describe the BeatLogic® platform for ECG interpretation and to validate the platform using electrophysiologist-adjudicated real-world data and publicly available validation data., Methods: Deep learning models were trained to perform beat and rhythm detection/classification using ECGs collected with the Preventice BodyGuardian® Heart monitor. Training annotations were created by certified ECG technicians, and validation annotations were adjudicated by a team of board-certified electrophysiologists. Deep learning model classification results were used to generate contiguous annotation results, and performance was assessed in accordance with the EC57 standard., Results: On the real-world validation dataset, BeatLogic beat detection sensitivity and positive predictive value were 99.84% and 99.78%, respectively. Ventricular ectopic beat classification sensitivity and positive predictive value were 89.4% and 97.8%, respectively. Episode and duration F 1 scores (range 0-100) exceeded 70 for all 14 rhythms (including noise) that were evaluated. F 1 scores for 11 rhythms exceeded 80, 7 exceeded 90, and 5 including atrial fibrillation/flutter, ventricular tachycardia, ventricular bigeminy, ventricular trigeminy, and third-degree heart block exceeded 95., Conclusion: The BeatLogic platform represents the next stage of advancement for algorithmic ECG interpretation. This comprehensive platform performs beat detection, beat classification, and rhythm detection/classification with greatly improved performance over the current state of the art, with comparable or improved performance over previously published algorithms that can accomplish only 1 of these 3 tasks., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Heart rate variability is a commonly used measurement to evaluate functioning of autonomic nervous system, psychophysiological stress, and exercise intensity and recovery. HRV measurements contain artefacts such as extra, missed or misaligned beat detections, which can produce significant distortion on HRV parameters. In this paper, a robust automatic method for artefact detection from HRV time series is proposed. Methods: The proposed detection method is based on time-varying thresholds estimated from distribution of successive RR-interval differences combined with a novel beat classification scheme. The method is validated using simulated extra, missed and misaligned beat detections as well as real artefacts such as atrial and ventricular ectopic beats. Results: The sensitivity of the algorithm to detect simulated missed/extra beats was 100%. The sensitivity to detect real atrial and ventricular ectopic beats was 96.96%, the corresponding specificity being 99.94%. The mean error in HRV parameters after correction was <2% for missed and extra beats as well as for misaligned beats generated with large displacement factors. Misaligned beats with smallest displacement factor were the most difficult to detect and resulted in largest HRV parameter errors after correction, largest errors being <8%. Conclusions: The HRV artefact correction algorithm presented in this study provided comparable specificity and better sensitivity to detect ectopic beats as compared to state-of-the-art algorithms. The proposed algorithm detects abnormal beats with high accuracy, is relatively easy to implement, and secures reliable HRV analysis by reducing the effect of possible artefacts to tolerable level.

The diagnosis of a Hisian extrasystole is based on simple electrocardiographic features and both an extrasystole arising from the His-Bundle ("true" Hisian extrasystole) and also one from the proximal portion of the bundle branch ("pseudo" Hisian extrasystole) would be diagnosed as Hisian extrasystoles [1]. Here we report a case of "pseudo" Hisian extrasystole arising from the proximal portion of the left bundle branch and the successful catheter ablation was achieved in the right coronary cusp., (Copyright © 2018. Published by Elsevier Inc.)

Premature complexes are electrical impulses arising from atrial, junctional, or ventricular tissue, leading to premature heart beats. Premature atrial beats are much more frequent than those arising in the atrioventricular junction but less frequent than premature beats from the ventricles. Although they are usually benign and highly prevalent in the general population, they could trigger sustained supraventricular and ventricular arrhythmias, and cause cardiomyopathies. The aim of this article was to review the main electrocardiology features of premature complexes and discuss their implications in clinical practice., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Double ventricular response in dual atrioventricular (AV) nodal pathways can result in nonreentrant supraventricular tachycardia. Since this condition was first described in 1979, around 20 cases have been reported. Here, we present the case of a patient with a confirmed diagnosis of double ventricular response in dual AV nodal pathways resembling an interpolated premature beat who underwent successful radiofrequency ablation of the slow pathway.

Background: Coronary computed tomography angiography (coronary CTA) provides non-invasive evaluation of the coronary arteries with high precision for the detection of significant coronary artery disease (CAD)., Aim: To investigate whether irregular heart rhythm including atrial fibrillation and premature beats during data acquisition influences (i) radiation and contrast media exposure, (ii) number of non-evaluable coronary segments and (iii) diagnostic impact of coronary CTA., Methods: Twelve tertiary care centers with ≥64 slice CT scanners and ≥5 years of experience with cardiovascular imaging participated in this registry. Between 2009 and 2014, 4339 examinations were analysed in patients who underwent clinically indicated coronary CTA for suspected CAD. Clinical and epidemiologic data were gathered from all patients. In addition, clinical presentation, heart rate and rhythm during the scan, Agatston score, radiation and contrast media exposure and the diagnostic impact of coronary CTA were systematically analysed., Results: Of 4339 patients in total, 260 (6.0%) had irregular heart rhythm, whereas the remaining 4079 (94.0%) had stable sinus rhythm. Patients with irregular heart rhythm were older (63.2 ± 12.5yrs versus 58.6 ± 11.4yrs. p < 0.001), exhibited a higher rate of pathologic stress tests before CTA (37.1% versus 26.1%, p < 0.01) and higher heart rates during CTA compared to those with sinus rhythm (62.5 ± 11.6bpm versus 58.9 ± 8.5bpm, p < 0.001). Both contrast media exposure and radiation exposure were significantly higher in patients with irregular heart rhythm (90 mL (95%CI = 80-110 mL) versus 80 mL (95%CI = 70-90 mL) and 6.2 mSv (95%CI = 2.5-11.7) versus 3.3 mSv (95%CI = 1.7-6.9), p < 0.001 for both). Coronary CTA excluded significant CAD less frequently in patients with irregular heart rhythm (32.9% versus 44.8%, p < 0.001). This was attributed to the higher rate of examinations with at least one non-diagnostic coronary segment in patients with irregular heart rhythm (10.8% versus 4.6%, p < 0.001). Subsequent invasive angiography could be avoided in 47.2% of patients with irregular heart rhythm compared to 52.9% of patients with sinus rhythm (p = NS), whereas downstream stress testing was recommended in 3.2% of patients with irregular heart rhythm versus 4.0% of patients with sinus rhythm (p = NS)., Conclusion: A significant number of patients scheduled for coronary CTA have irregular heart rhythm in a real-world clinical setting. In such patients, heart rate during coronary CTA is higher, possibly resulting in (i) higher radiation and contrast agent exposure and (ii) more frequent coronary CTA examinations with at least one non-diagnostic coronary artery segment. However, this does not seem to lead to increased downstream stress testing or subsequent invasive procedures., (Copyright © 2018 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

A 32-year-old, otherwise healthy woman was admitted after successful out-of-hospital resuscitation due to ventricular fibrillation. Established cardiac, pulmonary, metabolic, and toxicological causes were excluded. However, persisting (biphasic) negative T waves in the inferior ECG leads and premature ventricular contractions (PVC) were noted. PVC morphology indicated a focus alternating between the posterior papillary muscle/the left posterior fascicle and the left ventricular outflow tract region/anterior papillary muscle. Echocardiography revealed a bileaflet mitral prolapse with mild mitral valve regurgitation. This case is a typical presentation of the recently described malignant bileaflet mitral valve prolapse syndrome. The patient was discharged without overt neurological deficit after implantation of a cardioverter-defibrillator.

Background: The underwater environment presents physiological challenges for the cardiovascular, renal and pulmonary systems. Increases in external hydrostatic pressure reduce the capacity of the venous compartment and cause blood to move toward the lung. The aim of this study was to evaluate retrospectively electrocardiographic (ECG) changes in a cohort of professional divers., Methods: Between January 2009 and January 2012, 225 randomly selected professional divers, 204 male (91%) and 21 female (9%) attended our clinic for their biannual diving medical assessment. Their ECG records were evaluated retrospectively., Results: The most common ECG abnormality observed was incomplete right bundle branch block (IRBBB) in 30 divers (13.3%). Eleven divers (4.9%) showed right QRS axis deviation (seven with IRBBB). Six divers had a sinus tachycardia; in four divers there was early repolarization; three divers had ventricular extrasystoles; one diver had ST elevation in lead V3; there was one with sinus arrhythmia and another with T-wave inversion in leads V2, V3 and aVF. These ECG changes were evaluated retrospectively by a cardiologist who made various recommendations for further review including bubble contrast echocardiography for IRBBB., Conclusions: No serious ECG abnormalities were identified, but IRBBB should be further investigated because of its association with persistent (patent) foramen ovale. Rapid cardiological review of ECGs could be achieved using modern communications technology, such as telecardiography, and further clinical investigations directed by specialist recommendation arranged promptly if indicated.

Hisian extrasystoles originate from the His bundle. They are rare and usually misdiagnosed. In fact, they manifest on the EKG, with a p' wave located before, in or after the QRS complex. More rarely, the extrasystole blocks the propagation of the influx to the ventricles simulating a Mobitz II atrioventricular (AV) block. We report the case of a 36-Year-old woman with no medical History, suffering from presyncope and palpitations at rest. Her physical examination and EKG were normal. The 24-hour Holter monitoring showed some long periods with unexpected blocked p waves but with no significant pause. Considering her young age and the absence of causes of AV block, we performed an intracardiac electrophysiological study which showed hisian extrasystoles with normal conduction tissue properties at baseline and under flecainide. The diagnosis of hisian extrasystoles simulating Mobitz II AV block was made. A simple monitoring with beta-blockers therapy was recommended. Hisian extrasystoles may simulate first or second degree AV block with different therapeutic and prognostic implications. Nevertheless, these hisian extrasystoles may be the marker of a vulnerable AV conduction, long-term follow up should be considered.

Background: An acute increase in blood pressure is associated with the occurrence of premature ventricular complexes (PVCs)., Objective: We aimed to study the timing of these PVCs with respect to afterload-induced changes in myocardial deformation in a controlled, preclinically relevant, novel closed-chest pig model., Methods: An acute left ventricular (LV) afterload challenge was induced by partial balloon inflation in the descending aorta, lasting 5-10 heartbeats (8 pigs; 396 inflations)., Results: Balloon inflation enhanced the reflected wave (augmentation index 30% ± 8% vs 59% ± 6%; P < .001), increasing systolic central blood pressure by 35% ± 4%. This challenge resulted in a more abrupt LV pressure decline, which was delayed beyond ventricular repolarization (rate of pressure decline 0.16 ± 0.01 mm Hg/s vs 0.27 ± 0.04 mm Hg/ms; P < .001 and interval T-wave to peak pressure 1 ± 12 ms vs 36 ± 9 ms; P = .008), during which the velocity of myocardial shortening at the basal septum increased abruptly (ie, postsystolic shortening) (peak strain rate -0.6 ± 0.5 s(-1) vs -2.5 ± 0.8 s(-1); P < .001). It is exactly at this time of LV pressure decline, with increased postsystolic shortening, and not at peak pressure, that PVCs occur (22% of inflations). These PVCs preferentially occurred at the basal and apical segments. In the same regions, monophasic action potentials demonstrated the appearance of delayed afterdepolarization-like transient depolarizations as origin of PVCs., Conclusion: An acute blood pressure increase results in a more abrupt LV pressure decline, which is delayed after ventricular repolarization. This has a profound effect on myocardial mechanics with enhanced postsystolic shortening. Coincidence with induced transient depolarizations and PVCs provides support for the mechanoelectrical origin of pressure-induced premature beats., (Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Primary cardiac arrhythmias are much less common in infants and children than adults and the symptoms presented may be vague and nonspecific. Though true emergencies due to unstable arrhythmias in children are rare it is critical to identify and appropriately manage these arrhythmias, since when left untreated, arrhythmias may lead to cardiopulmonary compromise and arrest. Most children with a primary arrhythmia present to a pediatrician, cardiologists, or emergency physicians before being referred to a pediatric cardiologist for assessment and management. Thus, the pediatricians, cardiologists, and emergency physicians have to be able to recognize the arrhythmia and in some cases to provide the acute treatment. This article is intended to provide diagnostic and management guidelines of the most common types of arrhythmias seen in children with structurally normal hearts.

If a patient has premature beats, it is essential to clarify whether they are associated with a heart disorder or some other disease. The basis for an examination for all patients is the rest-ECG. Ultrasound examination is indicated, if the symptoms are severe or findings indicating a heart disorder are present. The occurrence of severe symptoms, such as episodes of tachycardia and attacks of unconsciousness, is mapped in an interview and they are an indication for further investigations within specialized care. Atrial extrasystoles as such do not require any treatment unless they are accompanied by atrial fibrillation.

We present electrocardiograms of a 37 year-old male with frequent extrasystoles and second-degree atrioventricular block. Electrophysiological study confirmed the initial diagnosis of manifest and concealed His bundle ectopy as the cause of his brady- and tachyarrhythmia.

The presence of recurring arrhythmic events (also known as cardiac dysrhythmia or irregular heartbeats), as well as erroneous beat detection due to low signal quality, significantly affects estimation of both time and frequency domain indices of heart rate variability (HRV). A reliable, real-time classification and correction of ECG-derived heartbeats is a necessary prerequisite for an accurate online monitoring of HRV and cardiovascular control. We have developed a novel point-process-based method for real-time R-R interval error detection and correction. Given an R-wave event, we assume that the length of the next R-R interval follows a physiologically motivated, time-varying inverse Gaussian probability distribution. We then devise an instantaneous automated detection and correction procedure for erroneous and arrhythmic beats by using the information on the probability of occurrence of the observed beat provided by the model. We test our algorithm over two datasets from the PhysioNet archive. The Fantasia normal rhythm database is artificially corrupted with known erroneous beats to test both the detection procedure and correction procedure. The benchmark MIT-BIH Arrhythmia database is further considered to test the detection procedure of real arrhythmic events and compare it with results from previously published algorithms. Our automated algorithm represents an improvement over previous procedures, with best specificity for the detection of correct beats, as well as highest sensitivity to missed and extra beats, artificially misplaced beats, and for real arrhythmic events. A near-optimal heartbeat classification and correction, together with the ability to adapt to time-varying changes of heartbeat dynamics in an online fashion, may provide a solid base for building a more reliable real-time HRV monitoring device.

We describe the case of a 61-year-old woman who underwent successful catheter cryoablation of a symptomatic Hisian ectopy. Diagnosis was based on features of the HV interval assessed from a bipolar recording during mapping. The location of the arrhythmic focus was identified using simultaneous unipolar and bipolar recordings of the His electrogram. This case report highlights the use of 2 new criteria for the diagnosis and mapping of Hisian ectopy, and the successful use of cryothermia for the ablation of extrasystoles arising from the His bundle., (© 2011 Wiley Periodicals, Inc.)

We report the first documentation of spontaneous ventricular fibrillation by a loop recorder in a patient with an ECG pattern of early repolarization (ER) in the inferior leads and presenting with syncope.

Heart rate variability (HRV) analysis is affected by ectopic beats. An efficient method was proposed to deal with the ectopic beats. The method was based on trend correlation of the heart timing signal. Predictor of R-R interval (RRI) value at ectopic beat time was constructed by the weight calculation and the slope estimation of preceding normal RRI. The type of ectopic beat was detected and replaced by the predictor of RRI. The performance of the simulated signal after ectopic correction was tested by the standard value using power spectrum density (PSD) estimation, whereas the results of clinical data with ectopic beats were compared with the adjacent ectopic-free data. The result showed the frequency indexes after ectopy corrected had less error than other methods with the test of simulated signal and clinical data. It indicated our method could improve the PSD estimation in HRV analysis. The method had advantages of high accuracy and real time properties to recover the sinus node modulation.

An 84 year-old man with history of recurrent dizziness presented with first degree atrio-ventricular block (1° AVB) and periods of 2:1 AVB. An electrophysiological study revealed a predominant 1:1 AV conduction with markedly prolonged AH interval and frequent His bundle extrasystoles (H). A properly timed H could induce periods of 2:1 AV nodal block and 1:1 AV conduction could only resume following another properly timed H. Procainamide suppressed H. However, because of persistence of the patient symptoms, a permanent pacemaker was eventually inserted. The case illustrates a hitherto not described manifestation of H.

Introduction: The induction of atrial fibrillation (AF) by pulmonary vein (PV) ectopy is well described. The triggers for these PV ectopy are not so well understood. The intrinsic cardiac autonomic nervous system (ANS) has been suggested as a potential upstream regulator that may cause PV ectopy and atrial fibrillation (AF). We hypothesized that activation of the ANS by high frequency stimulation (HFS) of atrial ganglionated plexi (GP) can initiate PV ectopy., Methods and Results: During sinus rhythm in 12 patients undergoing ablation for paroxysmal AF, short bursts of HFS, synchronized to the local atrial refractory period, were delivered at presumed GP sites. Electrograms were recorded from catheters placed in the PV, coronary sinus (CS) and high right atrium (HRA). A total of 112 episodes of HFS were recorded, producing ectopic activity in 91 of 112 (81%) episodes. Of these 91 episodes, there were 46 episodes of isolated single ectopic beats, 5 episodes of double ectopic responses, 24 episodes of ectopy/tachycardia lasting <30 s, and 16 episodes of AF lasting >30 s. In 63 of 91 episodes, the PV catheter was placed adjacent to the stimulated GP, resulting in ectopy recorded earliest in the PV catheter in 48 of 63 (76%) episodes. In one patient, reproducible ectopy was shown to occur following AV nodal conduction delay in response to HFS. Without HFS, neither AV nodal conduction delay nor ectopy occurred., Conclusions: This study has demonstrated a direct link between activation of the intrinsic cardiac autonomic nervous system and pulmonary vein ectopy in humans., (© 2011 Wiley Periodicals, Inc.)

Electrocardiogram (ECG) is the P-QRS-T wave which indicates the electrical activity of the heart. The subtle changes in the amplitude and duration of the ECG signal depict the cardiac abnormality. It is very difficult to decipher these minute changes by the naked eye. Hence, a computer-aided diagnosis system will help the physicians to monitor the cardiac health. The ECG is a nonlinear and non-stationary signal. Hence, the hidden information in the ECG signal can be extracted using nonlinear method. In this paper, we have automatically classified normal and abnormal beats using higher order spectra (HOS) cumulants of wavelet packet decomposition (WPD). The abnormal beats are ventricular premature contractions (VPC) and Atrial premature contractions (APC). These HOS cumulant features of the WPD are subjected to principal component analysis (PCA) to reduce the number of features to five. Finally these features were fed to the support vector machine (SVM) with kernel functions for automatic classification. In our work, we have obtained the highest accuracy of 98.4% sensitivity and specificity of 98.9% and 98.0% respectively with radial basis function (RBF) kernel function and Meyer's wavelet (dmey) function. Our system is ready clinically to run on large amount of data sets.

Palpitations can be defined as an unpleasant feeling of heart beat, which is perceived as particularly fast, irregular or intense. This feeling is usually associated with perception of movements and hits in the chest. From the pathophysiological point of view, current knowledge of the neural pathways responsible for the perception of heart beat remains to be clearly elucidated. It has been hypothesized that these pathways include different structures located both at the intracardiac and extracardiac level. Palpitations are a widely diffused complaint in the general population, and particularly in subjects affected by structural heart disease. Clinical presentation makes it possible to divide palpitations into four groups: extrasystolic, tachycardic, anxiety-related, and intense. From the etiological point of view, palpitations may be divided into the following groups: palpitations caused by arrhythmias, by structural heart disease (non-arrhythmic), by psychiatric disease, by systemic noncardiac disease, and by drug or illicit substance assumption. The prompt detection of the causes of palpitations allows to identify clinical conditions potentially at high risk and to choose the most appropriate therapeutic approach.

Noninducibility of atrial fibrillation (AF) by additional electrograms-guided ablation may benefit the clinical outcome. This report illustrates the effect of adenosine triphosphate (ATP) injection on AF inducibility after pulmonary vein (PV) isolation. AF was triggered twice by ATP without PV reconnection. Meanwhile, complex fractionated atrial electrograms (CFAEs) were observed, and ablation targets on these sites appeared to be essential to the AF elimination. It suggests that CFAEs may contribute to the initiation of some AF. ATP may be useful to induce AF after proven PV isolation, and further ablation might be necessary to ensure efficacy after circumferential PV isolation.

Extrasystoles particularly premature atrial contractions noted during labour on the fetal heart rate monitoring strip are usually thought to be benign. In pregnancies complicated by fetal infection and/or the fetal inflammatory response syndrome, there are some data that extrasystoles noted during the intrapartum period may be related to neonatal sepsis and eventual poor neonatal outcome including death or neonatal encephalopathy. Additional observations are needed to substantiate this hypothesis.

Cardiovascular screening tests to prevent sudden cardiac death in athletes are discussed controversially, but they should include diligent patient history and physical examination as well as registration of an ECG. If palpitations or tachycardias are described or if preexcitation, supraventricular or ventricular arrhythmias are documented, further risk stratification is mandatory. Specifically the origin and the complexity of the arrhythmia need to be analyzed and any form of structural cardiac pathologies has to be ruled out. Sinus tachycardia, supraventricular and ventricular premature beats, atrial fibrillation as well as supraventricular and ventricular tachycardia may serve as substrate for palpitations. Each of these arrhythmias is associated with a different amount of cardiac risk and can be evidence for certain forms of structural cardiac disease. Recommendations to limit physical activity and specific treatment options depend on the type of the arrhythmia and the presence and the nature of underlying cardiac disease.

Background: Recent series suggest that magnetic resonance imaging (MRI) scanning can be performed safely in select patients with pacemakers or implantable cardioverter-defibrillators (ICDs). Limited data have been reported on ectopy during MRI scans in patients with pacemakers or ICDs. This study evaluated increased ectopy observed in patients with permanent pacemakers or ICDs undergoing MRI scanning of any landmark without peak specific absorption rate (SAR) limit., Methods: Fifty-two patients with a total of 119 leads underwent a total of 59 MRI scans of any landmark using usual protocols with standard peak SAR settings for the scan. No patient was pacemaker dependent. All devices were programmed to single-chamber demand mode (VVI) or dual-chamber demand mode (DDI) with a lower rate of 40 bpm.Both telemetry and pulse oximetry plethysmographic waveform were observed continuously throughout the scans for ectopy., Results: Increased ectopy was observed during seven scans. The ectopy in four scans was ventricular and had fixed coupling intervals of 1,500 and 3,000, and was likely due to device noise rejection behavior. The etiology of ectopy observed during the other three scans could not be determined. Ectopy could not be predicted by peak SAR, scan time duration, or landmark. No significant changes in pacing thresholds were seen postscan., Conclusions: The current series suggests that a minority of patients with implanted pacemakers may have MRI-related ectopy. A significant proportion of this ectopy may arise from normal device behavior within the MRI environment.

Aim of the study was to determine dynamics of main parameters of heart rhythm in children during first days of life. Material and methods. We examined 30 healthy newborns (14 boys and 16 girls) aged 1-4 days (2,6+/-1,3 days). Criteria of inclusion were healthy mother, normal course of pregnancy and delivery, gestational age at birth 38-40 weeks, body mass at birth 3200-3600 g; Algar score 8/9, no cardiovascular abnormalities at physical examination, informed consent of parents. On days 1-2 and 4 of life we carried out 12 lead ECG at rest and 24-hour Holter monitoring with assessment of heart rate (HR), arrhythmias, dynamics of QT-interval, HR variability (HRV) using methods "Time Domain" and "deceleration (DC)/acceleration capacity (AC)". Results. Average 24-hour HR was 138+/-17 beats/min, maximal pauses of sinus rhythm - 990 ms. Supraventricular extrasystoles (<10/24 hours) were registered in 35%, ventricular extrasystoles (<5/24 hours) in 15% of children. Values of HRV were as follows: N 442 (408-72) ms; SDNN 52 (43-75) ms; SDNNi 36 (35-61) ms; SDNNi24 (22-37) ms; SSD 14 (10-20) ms; NN50% 0,98(0-2,4)%. Analysis of D/ showed the following values: D = +3.43 +/- 0.54 (2.16-4.14),=-3.65+/-0.65 (from - 2.13 to - 4.38). Analysis of interval QT values: average 24-hour QT (QTo) - 293+/-10 (278-308) ms, maximal - 342+/-38 (328-360) ms; mean 24-hour QT 442+/-14 (428-470) ms; QT 204+/-11 (191-220) ms; QT - 308+/-17(284-337) ms, sl Q/RR 0.37 (0.304-0.505); intercept QT/RR 126 (92.0-151.0), correlation coefficient () QT/RR 0.65 (0.56-0.84). On day 4 compared with day 1 there were significantly higher values of correlation (r) QT/RR and lower values of sl QT/RR. Conclusions. During first days of life children can have supraventricular and ventricular extrasystoles (not more than 10 per 24 hours). First 24 hours of life are characterized by most pronounced signs of myocardial instability according to data of assessment of QT dynamics. HRV parameters of healthy newborns are characterized by high level of sympathetic activity, symmetry of deceleration capacity/acceleration capacity parameters.

Background: Laryngoscopy and intubation are associated with marked autonomic system activation that can be assessed by heart rate variability analysis (HRV)--a new method, comparing R-R intervals in 12-lead continuous ECG recording., Methods: Fifty-two ASA I and II adults patients of both sexes were enrolled in the study. Patients were induced with fentanyl and thiopental, paralysed with vecuronium, and intubated. Continuous ECG was recorded and selected time-domain parameters (RMSSD, SDNN, NN50 and pNN50) were analyzed before and after intubation at 5- min intervals., Results: Endotracheal intubation resulted in transient supraventricular and ventricular extrasystoles in six patients. Seven patients developed transient bigeminy. Equivocal changes of RMSSD, SDNN, NN50 and pNN50 were observed., Conclusion: Because of the large incidence of cardiac rhythm disturbances, the HRV proved to be useless for assessment of autonomic system changes.

We discuss the electrocardiogram and differential diagnosis of an apparent type II second-degree atrioventricular block recorded in a 15-year-old girl after successful radiofrequency ablation of a left-sided concealed accessory pathway.