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Photoplethysmography (PPG) signal is potentially suitable in atrial fibrillation (AF) detection for its convenience in use and similarity in physiological origin to electrocardiogram (ECG). There are a few preceding studies that have shown the possibility of using the peak-to-peak interval of the PPG signal (PPIp) in AF detection. However, as a generalized model, the accuracy of an AF detector should be pursued on the one hand; on the other hand, its generalizability should be paid attention to in view of the individual differences in PPG manifestation of even the same arrhythmia and the existence of sub-types. Moreover, a binary classifier for atrial fibrillation and normal sinus rhythm is not convincing enough for the similarity between AF and ectopic beats. In this study, we project the atrial fibrillation detection as a multiple-class classification and try to propose a training pipeline that is advantageous both to the accuracy and generalizability of the classifier by designing and determining the configurable options of the pipeline, in terms of input format, deep learning model (with hyperparameter optimization), and scheme of transfer learning. With a rigorous comparison of the possible combinations of the configurable components in the pipeline, we confirmed that first-order difference of heartbeat sequence as the input format, a 2-layer CNN-1-layer Transformer hybridR model as the learning model and the whole model fine-tuning as the implementing scheme of transfer learning is the best combination for the pipeline (F1 value: 0.80, overall accuracy: 0.87)R.

Photoplethysmography (PPG) signal is potentially suitable in atrial fibrillation (AF) detection for its convenience in use and similarity in physiological origin to electrocardiogram (ECG). There are a few preceding studies that have shown the possibility of using the peak-to-peak interval of the PPG signal (PPIp) in AF detection. However, as a generalized model, the accuracy of an AF detector should be pursued on the one hand; on the other hand, its generalizability should be paid attention to in view of the individual differences in PPG manifestation of even the same arrhythmia and the existence of sub-types. Moreover, a binary classifier for atrial fibrillation and normal sinus rhythm is not convincing enough for the similarity between AF and ectopic beats. In this study, we project the atrial fibrillation detection as a multiple-class classification and try to propose a training pipeline that is advantageous both to the accuracy and generalizability of the classifier by designing and determining the configurable options of the pipeline, in terms of input format, deep learning model (with hyperparameter optimization), and scheme of transfer learning. With a rigorous comparison of the possible combinations of the configurable components in the pipeline, we confirmed that first-order difference of heartbeat sequence as the input format, a 2-layer CNN–1-layer Transformer hybridR model as the learning model and the whole model fine-tuning as the implementing scheme of transfer learning is the best combination for the pipeline (F1 value: 0.80, overall accuracy: 0.87)R. [ABSTRACT FROM AUTHOR]

Background: Occurrence of nonsustained ventricular tachycardia (NSVT) is associated with negative outcomes. It is not clear whether specific electrocardiographic characteristics of premature ventricular contractions (PVCs) are associated with the occurrence of NSVT. The aim of this study was to identify electrocardiographic patterns associated with the presence of NSVT during 24-h electrocardiographic monitoring in patients with >10 PVCs per hour., Methods: This was a retrospective, observational, cross-sectional study. We reviewed consecutive patients who received 24-h ECG monitoring performed at a single outpatient cardiology center. Patients who received 24-h electrocardiographic monitoring, with a PVC burden ≥10 PVCs/h were included. Occurrence of NSVT during 24-h electrocardiographic monitoring was the main outcome., Results: A total of 343 patients were analyzed (mean [SD] age, 69.7 [12.5] years; 177 men [51.6 %]). NSVT occurred in 72 patients who were compared with 271 patients without NSVT. The novel term "premature beat ratio", which aims to correlate the coupling interval and compensatory pause, was introduced; a value >0.5 was independently associated with NSVT according to the multivariate model (OR = 3.73, 95 % CI = 1.57-8.82; P = 0.002). PVC burden (OR = 1.09, 95 % CI = 1.02-1.17; P = 0.006), and triplets (OR = 18.19, 95 % CI = 7.32-45.18 P = 0.0) were also associated with NSVT in the multivariate model., Conclusion: These findings suggest that patients with a high PVC burden, triplets, and a premature beat ratio greater than 0.5 have an increased probability of presenting with NSVT and may benefit from more rigorous follow-up., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Abstract Background Bradycardia and syncope are known sequelae of brain lesions. However, in the absence of neurological signs and symptoms, bradycardia and syncope are often investigated purely from the cardiovascular perspective and central nervous system-related causes may be easily overlooked during differential diagnosis. Case presentation Here we report a case of a 69-year-old Caucasian man who presented to the emergency department after a fall. He had 1-year history of syncope and bradycardia with frequent ectopic beats shown on his electrocardiogram. He had no neurological symptoms. He was previously investigated as an out-patient and a diagnosis of idiopathic bradycardia with ventricular ectopic beats was made. On admission, cardiovascular investigations could not reveal the cause of his bradycardia. Computed tomography and magnetic resonance imaging scans of his head showed a localized mass in left basal ganglia consistent with infiltrating glioma. Conclusion To the best of our knowledge this is the first case report demonstrating central nervous system-related bradycardia and syncope without other neurological symptoms. This case will serve as a useful reminder to general practitioners, accident and emergency doctors, and cardiologists.

An editorial is presented on Catheter ablation of atrial fibrillation (AF) has become a first‐line therapeutic option with Pulmonary vein isolation (PVI) has become an effective approach for paroxysmal AF ablation. Topics include suggested the electrophysiological determinant factors of AF initiation from the PVs; and longitudinal PV‐LA conduction delay but also a circumferential conduction delay contributes to AF initiation.

Background & aims : Normally four pulmonary veins open into the left atrium. Frequently there are variations in the number of pulmonary veins opening in to the left atrium. Ectopic beats in atrial fibrillation commonly originates from the ostia of the pulmonary veins. The treatment of atrial fibrillation is by radio frequency ablation of the focus of origin and hence the knowledge of anatomical variation of pulmonary veins is necessary to find the ectopic focus in the origin of atrial fibrillation. Materials and Method : In this study the variation of pulmonary venous ostia pattern in the left atrium was studied in 80 formalin fixed adult cadaveric hearts. Results and Conclusion : 63 hearts showed no variation in the pulmonary venous ostia pattern which accounts for 78.75%, rest of the 17 hearts showed variation in the pulmonary venous ostia which accounts for 21.25%, the variation in the number of pulmonary veins was slightly higher for the left side [11.25%] when compared to the right sided variation [10%], the number of hearts which showed bilateral variation was noted in 2 hearts - both showed a single pulmonary vein opening on either side which accounts for 2.5%

Although premature ventricular beats (PVBs) in young people and athletes are usually benign, they may rarely mark underlying heart disease and risk of sudden cardiac death during sport. This review addresses the prevalence, clinical meaning and diagnostic/prognostic assessment of PVBs in the athlete. The article focuses on the characteristics of PVBs, such as the morphological pattern of the ectopic QRS and the response to exercise, which accurately stratify risk. We propose an algorithm to help the sport and exercise physician manage the athlete with PVBs. We also address (1) which athletes need more indepth investigation, including cardiac MRI to exclude an underlying pathological myocardial substrate, and (2) which athletes can remain eligible to competitive sports and who needs to be excluded. [ABSTRACT FROM AUTHOR]

Background: Bradycardia and syncope are known sequelae of brain lesions. However, in the absence of neurological signs and symptoms, bradycardia and syncope are often investigated purely from the cardiovascular perspective and central nervous system-related causes may be easily overlooked during differential diagnosis.Case Presentation: Here we report a case of a 69-year-old Caucasian man who presented to the emergency department after a fall. He had 1-year history of syncope and bradycardia with frequent ectopic beats shown on his electrocardiogram. He had no neurological symptoms. He was previously investigated as an out-patient and a diagnosis of idiopathic bradycardia with ventricular ectopic beats was made. On admission, cardiovascular investigations could not reveal the cause of his bradycardia. Computed tomography and magnetic resonance imaging scans of his head showed a localized mass in left basal ganglia consistent with infiltrating glioma.Conclusion: To the best of our knowledge this is the first case report demonstrating central nervous system-related bradycardia and syncope without other neurological symptoms. This case will serve as a useful reminder to general practitioners, accident and emergency doctors, and cardiologists. [ABSTRACT FROM AUTHOR]

During cardiac diseases many types of anatomical and functional remodeling of cardiac tissue can occur. In this work, we focus on two conditions: hypoxia and fibrosis, which are part of complex pathological modifications that take place in many cardiac diseases (hypertrophic cardiomyopathy, hypertensive heart disease, and recurrent myocardial infarction) and respiratory diseases (obstructive pulmonary disease, obstructive sleep apnea, and cystic fibrosis). Using computational models of cardiac electrophysiology, we evaluate if the interplay between hypoxia and fibrosis is sufficient to trigger cardiac arrhythmia. We study the mechanisms behind the generation of ectopic beats, an arrhythmic trigger also known as premature ventricular contractions (PVCs), in regions with high hypoxia and fibrosis. First, we modify an electrophysiological model of myocytes of the human left ventricle to include the effects of hypoxia. Second, diffuse fibrosis is modeled by randomly replacing cardiac myocytes by non-excitable and non-conducting cells. The Monte Carlo method is used to evaluate the probability of a region to generate ectopic beats with respect to different levels of hypoxia and fibrosis. In addition, we evaluate the minimum size of three-dimensional slabs needed to sustain reentries for different stimulation protocols. The observed mechanism behind the initiation of ectopic beats is unidirectional block, giving rise to sustained micro-reentries inside the region with diffuse fibrosis and hypoxia. In summary, our results suggest that hypoxia and fibrosis are sufficient for the creation of a focal region in the heart that generates PVCs.

During cardiac diseases many types of anatomical and functional remodeling of cardiac tissue can occur. In this work, we focus on two conditions: hypoxia and fibrosis, which are part of complex pathological modifications that take place in many cardiac diseases (hypertrophic cardiomyopathy, hypertensive heart disease, and recurrent myocardial infarction) and respiratory diseases (obstructive pulmonary disease, obstructive sleep apnea, and cystic fibrosis). Using computational models of cardiac electrophysiology, we evaluate if the interplay between hypoxia and fibrosis is sufficient to trigger cardiac arrhythmia. We study the mechanisms behind the generation of ectopic beats, an arrhythmic trigger also known as premature ventricular contractions (PVCs), in regions with high hypoxia and fibrosis. First, wemodify an electrophysiologicalmodel ofmyocytes of the human left ventricle to include the effects of hypoxia. Second, diffuse fibrosis is modeled by randomly replacing cardiac myocytes by non-excitable and non-conducting cells. The Monte Carlo method is used to evaluate the probability of a region to generate ectopic beats with respect to different levels of hypoxia and fibrosis. In addition, we evaluate the minimum size of three-dimensional slabs needed to sustain reentries for different stimulation protocols. The observed mechanism behind the initiation of ectopic beats is unidirectional block, giving rise to sustainedmicro-reentries inside the region with diffuse fibrosis and hypoxia. In summary, our results suggest that hypoxia and fibrosis are sufficient for the creation of a focal region in the heart that generates PVCs. [ABSTRACT FROM AUTHOR]

Frequent ectopic beats in patients under hemodialysis may be associated with the occurrence of life-threatening arrhythmias. However, data regarding the prognostic significance of ectopic beats are limited due to the lack of accessible technology for long-term monitoring. This study aims to investigate the feasibility to assess the ectopic burden from continuously acquired wrist photoplethysmogram (PPG). The performance of two PPG-based ectopic beat detectors operating on the pulse-to-pulse basis was investigated against the reference ectopic beats detected from the electrocardiogram using 41 24-h recordings obtained from hemodialysis patients under uncontrolled conditions. The estimation accuracy of an average daily ectopic burden and the detection performance of high-risk ectopic burden (≥ 30 beats/h) were also compared to the reference electrocardiogram. The sensitivity and positive predictive value of 68.1% and 59.5%, respectively, were reached by the better-performing PPG-based ectopic beat detector. A PPG-based average daily ectopic burden was estimated with a median error of 3 beats/h. Sensitivity of 82.7% and specificity of 89.8% were achieved when identifying high-risk ectopic burden in 1-h segments with at least 75% of acceptable-quality PPG. The study demonstrates the potential of the wrist PPG to monitor ectopic burden in an outpatient setting and identify patients eligible for early antiarrhythmic treatment. • Wrist photoplethysmogram (PPG) can be applied to ectopic burden estimation. • PPG-based monitoring facilitates the identification of high-risk ectopic burden. • Accuracy of ectopic burden estimation relies on PPG quality and its assessment. [ABSTRACT FROM AUTHOR]

Adolescents and adults with cardiovascular disease who are engaged in sports activity have an increased risk of sudden cardiac death ( SCD) that is three times greater than that of their non-athletic counterparts. Sport acts as a trigger for cardiac arrest in the presence of underlying cardiovascular diseases predisposing to life-threatening ventricular arrhythmias. Frequent and complex premature ventricular beats ( PVBs) detected during the cardiovascular screening of the athletic population may be a sign of an underlying cardiovascular disease at risk of SCD, but are also often recorded in trained athletes without cardiovascular abnormalities. Thus, the interpretation of PVBs could represent a clinical dilemma, particularly in the athlete. However, while some characteristics of PVBs can be considered common and benign, others occur uncommonly in the athletic population and raise the suspicion of an underlying cardiovascular disease. This review discusses the prevalence and clinical significance of PVBs in the athlete, with a focus on exercise-induced PVBs, on the analysis of PVB's morphology at 12-lead ECG, and on the morphological substrates identified by imaging techniques. The implications on eligibility for competitive sports participation are also discussed, according to the relevance of PVB detection for disqualifying athletes from competitions. [ABSTRACT FROM AUTHOR]

Hemodialysis patients often suffer from cardiovascular disorders and uremic neuropathy, increasing the propensity to homeostatic imbalance that, in turn, may result in intradialytic complications like cramp, nausea, and, worse, hypotension. Ectopic beats, being abundant in such patients, may lead to imbalance through repeated, sudden drops in blood pressure. By exploring the properties of postectopic peripheral circulation recovery, treatment sessions prone to intradialytic complications may be better identified. This paper introduces a novel method for quantifying changes in peripheral blood volume due to ventricular or supraventricular premature beats (VPBs or SVPBs). Using the fingertip photoplethysmographic pulse waveform, VPB and SVPB-induced changes in relative peripheral blood volume are quantified by the postectopic pulse amplitude. Two parameters are proposed for characterizing (i) the initial drop in peripheral blood volume following an ectopic beat, and (ii) the degree of postectopic peripheral circulation recovery. A small set of data from 16 hemodialysis sessions in 9 hypotension-prone patients are used to illustrate the method. In asymptomatic sessions, the first parameter was found to be 8 ± 13% (mean ± std), whereas, in symptomatic sessions, it increased to 32 ± 13%, suggesting that postectopic pulse amplitude recovery is related to intradialytic complications; similar results were obtained for the second parameter. Postectopic pulse amplitude recovery may also be of interest in other applications where relative changes in peripheral blood volume play a role. [ABSTRACT FROM AUTHOR]

Photoplethysmography (PPG) signal is potentially suitable in atrial fibrillation (AF) detection for its convenience in use and similarity in physiological origin to electrocardiogram (ECG). There are a few preceding studies that have shown the possibility of using the peak-to-peak interval of the PPG signal (PPIp) in AF detection. However, as a generalized model, the accuracy of an AF detector should be pursued on the one hand; on the other hand, its generalizability should be paid attention to in view of the individual differences in PPG manifestation of even the same arrhythmia and the existence of sub-types. Moreover, a binary classifier for atrial fibrillation and normal sinus rhythm is not convincing enough for the similarity between AF and ectopic beats. In this study, we project the atrial fibrillation detection as a multiple-class classification and try to propose a training pipeline that is advantageous both to the accuracy and generalizability of the classifier by designing and determining the configurable options of the pipeline, in terms of input format, deep learning model (with hyperparameter optimization), and scheme of transfer learning. With a rigorous comparison of the possible combinations of the configurable components in the pipeline, we confirmed that first-order difference of heartbeat sequence as the input format, a 2-layer CNN -1-layer Transformer hybrid R model as the learning model and the whole model fine-tuning as the implementing scheme of transfer learning is the best combination for the pipeline (F1 value: 0.80, overall accuracy: 0.87) R ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Kudo, Chen, Zhou, Izu, Chen-Izu, Zhu, Tamura, Kanaya and Huang.)

Background A high percentage of biventricular pacing is required for optimal outcome in patients treated with cardiac resynchronization therapy (CRT), but the influence of ectopic beats on the success of biventricular pacing has not been well established. Objectives This study sought to determine if increased ectopic beats reduce the chance of high biventricular pacing percentage and are associated with subsequent adverse outcomes. Methods From the MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy), 801 patients with an implanted CRT-defibrillator device with data available on biventricular pacing percentage and pre-implantation 24-h Holter recordings were included. Using logistic regression, we estimated the influence of ectopic beats on the percentage of biventricular pacing. Reverse remodeling was measured as reductions in atrial and left ventricular end-systolic volumes (LVESV) at 1 year. Cox models were used to assess the influence of ectopic beats on the outcomes of heart failure (HF) or death, ventricular tachyarrhythmias (VTAs), and death. Results In the pre-implantation Holter recording, ectopic beats accounted for a mean 3.2 ± 5.5% of all beats. The probability of subsequent low biventricular pacing percentage (<97%) was increased 3-fold (odds ratio: 3.37; 95% confidence interval: 1.74 to 6.50; p < 0.001) in patients with 0.1% to 1.5% ectopic beats and 13-fold (odds ratio: 13.42; 95% confidence interval: 7.02 to 25.66; p < 0.001) in patients with >1.5% ectopic beats compared with those with <0.1% ectopic beats. Patients with ≥0.1% ectopic beats had significantly less reverse remodeling (percent reduction in LVESV 31 ± 15%) than patients with <0.1% ectopic beats (percent reduction in LVESV 39 ± 14%; p < 0.001). The risk of HF/death and VTA was increased significantly in those with 0.1% to 1.5% ectopic beats (hazard ratio: 3.13 and 1.84, respectively) and for >1.5% ectopic beats (hazard ratio: 2.38 and 2.74, respectively). Conclusions Relatively low frequencies of ectopic beats (≥0.1%) dramatically increase the probability of low biventricular pacing (<97%), with reduced CRT efficacy by less reverse remodeling and higher risk of HF/death and VTA. This supports pre-implantation Holter monitoring of patients selected for CRT for optimal outcome. (MADIT-CRT: Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization Therapy; NCT00180271 ) [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

Approximate entropy (ApEn) and sample entropy (SampEn) are the promising techniques for extracting complex characteristics of cardiovascular variability. Ectopic beats, originating from other than the normal site, are the artefacts contributing a serious limitation to heart rate variability (HRV) analysis. The approaches like deletion and interpolation are currently in use to eliminate the bias produced by ectopic beats. In this study, normal R–R interval time series of 10 healthy and 10 acute myocardial infarction (AMI) patients were analysed by inserting artificial ectopic beats. Then the effects of ectopic beats editing by deletion, degree-zero and degree-one interpolation on ApEn and SampEn have been assessed. Ectopic beats addition (even 2%) led to reduced complexity, resulting in decreased ApEn and SampEn of both healthy and AMI patient data. This reduction has been found to be dependent on level of ectopic beats. Editing of ectopic beats by interpolation degree-one method is found to be superior to other methods. [ABSTRACT FROM PUBLISHER]

A growing trend among clinical studies is the use of heart rate monitors (HRMs) for assessment of heart rate variability (HRV). These instruments offer a convenient alternative to traditional electrocardiographs (ECGs) for recording and processing of R-R data. Reports on the validity of such systems are, however, conflicting. This study aimed to assess the validity of a commercial HRM on a large study sample, with emphasis on gender and age. Simultaneous recordings of R-R intervals were conducted with the Polar RS800 HRM and a 3-lead ECG on 341 individuals. Data editing was performed with individually designated software for each instrument. Agreement on SDNN, RMSSD, and HF- and LF power was assessed with intraclass correlations (ICCs), standard errors of measurement (SEMs) and Bland and Altman plots. The HRM was not able to identify 18 observations with non-sinus beats. For men, agreement between instruments ranged from good to excellent (ICC ≥ 0.8) on all HRV measures, and SEMs were generally small. For women the results were weaker, with unacceptable agreement between instruments on SDNN. Women over 60 years did not reach a critical ICC value of 0.75 on any of the HRV measures. Bland and Altman plots demonstrated that the RS800 generally overestimated HRV, and that uncertainty increased with higher values. Since the Polar system did not identify errors satisfactorily, or return valid values of HRV for certain groups, it is concluded that, whenever possible, traditional ECGs should be used for both gathering and editing of HRV data. [ABSTRACT FROM AUTHOR]

Non-invasive localization of premature ventricular beat (PVB) foci is very important for medical treatment of numerous cardiac diseases. In this work a model-based method of reconstruction of ectopic center locations is investigated. Within the scope of this method patient's multichannel ECG is used as a reference for optimization of an electrophysiological cardiac model. This model is based on the cellular automaton principle and utilizes anatomical data of the patient. Optimized are coordinates of the ectopic focus as well as excitation conduction velocity of ventricular myocardium. Initial values for these parameters are obtained by solving the linearized problem of electrocardiography in terms of activation times. Optimization is performed by minimization of discrepancy between the simulated and reference ECGs. The aim of the current work is to estimate the quality of ectopic focus localization delivered by this method. Four sample ectopic beats have been simulated, with their foci located in different regions of the left ventricle. 1% Gaussian noise has been introduced into the resulting ECGs. In this way the "measured" ECG signals for this investigation have been obtained. Afterwards the origin of each ectopic beat has been reconstructed using themodel-based approach. Themethod has demonstrated reliable localization of PVB foci, reconstruction errors have not exceeded 6.1 mm. [ABSTRACT FROM AUTHOR]

This study presents an efficient method based on principal component analysis (PCA) to remove ectopic beats in R-R intervals. The method is focused on variation of slopes at each time steps and reconstruction of new time values using initial eigenvectors and new slope values. Obtained results and LF (low frequency) and HF (high frequency) energy distributions were compared with outputs of integral pulse frequency modulation (IPFM) method and sliding window average filter (SWAF). [ABSTRACT FROM AUTHOR]

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Mapping in a patient undergoing radiofrequency ablation for drug-refractory paroxysmal atrial fibrillation in the setting of repetitive, monomorphic atrial ectopic beats with negative p waves in the inferior leads revealed an arrhythmogenic focus located in the posteromedial inferior vena cava (IVC) 1 cm below the right atrium to IVC junction. The focus was mapped using a Lasso catheter with successful irrigated-tip catheter ablation at the site of earliest activity. This case demonstrates that, in rare cases, arrhythmogenic muscular sleeves can be found in the IVC and that the IVC can be electrically disconnected from the right atrium using radiofrequency energy. (J Cardiovasc Electrophysiol, Vol. 14, pp. 659-662, June 2003). [ABSTRACT FROM AUTHOR]

Ectopic beats triggering atrial fibrillation may arise from atrial myocardial extensions in the pulmonary veins, superior vena cava, coronary sinus, and vein of Marshall. We report two patients with paroxysmal atrial fibrillation initiated by ectopic beats originating from the inferior vena cava. The foci responsible for the ectopic beats were located and ablated, resulting in elimination of atrial fibrillation. Ectopic beats originating from the os of the inferior vena cava can result in atrial fibrillation. This finding may explain the recurrence of atrial fibrillation in some patients after pulmonary vein isolation. [ABSTRACT FROM AUTHOR]

Background: Magnesium has been suggested to be beneficial in counteracting all phases of the processes that lead to ischemic heart disease, including terminal events such as arrhythmia and sudden death. Objective:We tested the hypothesis that an intake of magnesium considerably below the recommended dietary allowance can produce chemical and physiologic evidence of depletion. Design: Twenty-two postmenopausal women were maintained in a metabolic unit and ate a diet of conventional foods containing less than one-half of or more than the recommended dietary allowance for magnesium (320 mg/d). Dietary assignments were random and double blind in a crossover design. Magnesium concentrations were measured by spectroscopy and ion-specific electrolyte analysis, and Holter electrocardiograms lasting ≈21 h were recorded. Results: Magnesium concentrations in erythrocytes, serum (total and ultrafilterable), and urine were significantly lower when dietary magnesium was lower. Holter monitors showed a significant increase in both supraventricular and supraventricular plus ventricular beats when the dietary magnesium concentration was low. Hypomagnesemia, hypocalcemia, and hypokalemia were not found. Conclusions: The magnesium requirement was defined with the use of biochemical and electrophysiologic criteria. The recommended dietary allowance of 320 mg/d seems correct; 130 mg is too little. Persons who live in soft water areas, who use diuretics, or who are predisposed to magnesium loss or ectopic beats may require more dietary magnesium than would others. [ABSTRACT FROM AUTHOR]

Ectopic activity originating in the right ventricular outflow tract is a frequent finding and may result in severe symptoms such as dyspnea, palpitations, and lack of physical capacity correlated with a low cardiac output. In 12 consecutive symptomatic and drug refractory patients, we performed a study with intracardiac mapping and ablation procedure. The origin of the ectopic beats was identified, and the ablation procedure was performed. Patients were examined by serial ECG, Holter ECG. bicycle ECG, echocardiography, and thoracic X ray. At baseline, the mean number of ectopic beats was 23,823 during Holter ECG. No other arrhythmias were present. Patients underwent basic electro-physiological study, mapping process, and ablation in a single procedure. Ablation was performed with a deflectable thermocoupled catheter with tip electrodes of 4 mm. Criteria for identification of the origin of the ectopic beats included pace mapping with 12 leads and earliest endocardial activation. One male patient suffered from myocarditis; the other 11 patients had no underlying structural heart disease. The mean age was 38 years. Ablation procedure with delivered temperature of 70°C was successful in 11 of 12 patients eliminating the focus. The mean procedural time was 79 ± 34 minutes; mean fluoroscopy time was 13.8 ± 8.8 minutes; and mean number of applications was 4.4 ± 2.8. No adverse effects occurred during a follow-up period of 10 months after ablation. The mean number of ectopic beats per 24 hours after ablation was 317 ± 599 with a P value of 0.00024. The clinical symptoms improved in all but one patient. One patient had a recurrence after 2 months that could be successfully treated by a second procedure. In our experience, temperature guided radiofrequency catheter ablation is safe and effective for the treatment of patients with symptomatic ectopic activity of the right outflow tract. As long as we lack the experience of a greater patient... [ABSTRACT FROM AUTHOR]

Abstract Background Premature ventricular complexes (PVC) predict cardiovascular mortality among several adult populations. Increased arrhythmia prevalence has been reported during controlled magnesium (Mg) depletion studies in adults. We thus hypothesized that serum magnesium (sMg) concentrations are inversely associated with the prevalence of PVC in adults at high cardiovascular risk. Methods Anthropometric, demographic and lifestyle characteristics were assessed in 750 Cree adults, aged > 18 yrs, who participated in an age-stratified, cross-sectional health survey in Quebec, Canada. Holter electrocardiograms recorded heart rate variability and cardiac arrhythmias for two consecutive hours. Multivariate logistic regression was used to evaluate the associations between sMg and PVC. Results PVC prevalence in adults with hypomagnesemia (sMg ≤ 0.70 mmol/L) was more than twice that of adults without hypomagnesemia (50% vs. 21%, p = 0.015); results were similar when adults with cardiovascular disease history were excluded. All hypomagnesemic adults with PVC had type 2 diabetes (T2DM). Prevalence of PVC declined across the sMg concentration gradient in adults with T2DM only (p < 0.001 for linear trend). In multivariate logistic regressions adjusted for age, sex, community, body mass index, smoking, physical activity, alcohol consumption, kidney disease, antihypertensive and cholesterol lowering drug use, and blood docosahexaenoic acid concentrations, the odds ratio of PVC among T2DM subjects with sMg > 0.70 mmol/L was 0.24 (95% CI: 0.06-0.98) p = 0.046 compared to those with sMg ≤ 0.70 mmol/L. Conclusions sMg concentrations were inversely associated with the prevalence of PVC in patients with T2DM in a dose response manner, indicating that suboptimal sMg may be a contributor to arrhythmias among patients with T2DM.