Supraventricular Tachycardia Research Articles

IMPLANTABLE LOOP RECORDER IN BRUGADA SYNDROME: INSIGHTS FROM A SINGLE–CENTER EXPERIENCE

Abstract Brugada syndrome (BrS) is characterized by a “coved” ST segment elevation of ≥2 mm in the right precordial electrocardiographic (ECG) leads, either spontaneously or drug–induced. Risk stratification in individuals with BrS remains challenging. Currently, miniaturized and remotely monitored implantable loop recorders (ILRs) are available, providing physicians with a diagnostic tool that can help guide intervention or therapy decisions for these patients. The objective of this study was to investigate the characteristics and outcomes of patients diagnosed with BrS who underwent ICM insertion during routine clinical activity. This is a retrospective single center cohort study. We screened 147 consecutive patients who were diagnosed with BrS based on the presence of spontaneous or drug–induced type 1 ECG pattern between January 2009 and May 2023. Once this comprehensive diagnostic pathway was completed, we engaged in detailed counseling with patients to discuss the potential need for ICD implantation or ILR insertion, if deemed indicated. Compared to patients who did not receive a device, those who received an ILR had a higher prevalence of suspected arrhythmic syncope (43% vs. 22%, p=0.012) and tended to be younger (median age 38 years, IQR 30–52, vs. 43 years, IQR 35–55, p=0.044) and with a higher presence of SCN5A gene mutations (17% vs. 6%). On the other hand, compared to patients who received an ICD, those with an ICM underwent programmed ventricular stimulation less frequently (40% vs. 85%, p=0.010) and, as a result, had a lower frequency of positive result of this test (0% vs. 91%, p< 0.001). During a median follow–up period of 14.7 months (IQR, 4.7–44.8), no deaths occurred among the patients with ILR. Eight individuals (19%) were diagnosed with arrhythmic findings through continuous ILR monitoring. Among these findings, three patients experienced AF (including one case of new–onset AF), two patients exhibited symptomatic asystolic pauses lasting 16 seconds and 3.6 seconds respectively, two patients had non–sustained ventricular tachycardia, and one patient had episodes of paroxysmal supraventricular tachycardia. Except for a history of AF, no significant differences were observed between patients with arrhythmic findings and those without any events. In the ICD group, the median follow–up period was 32.2 months (IQR, 23.2–95.0). During this period, no deaths occurred and no appropriate or inappropriate ICD therapies were delivered.

Cardiac arrhythmias in patients with type 2 diabetes mellitus

Introduction. The contribution of type 2 diabetes mellitus (type 2 diabetes) and cardiovascular diseases (CVD) to the increase in disability and mortality rates worldwide continues to grow steadily. Currently, the main focus is on the problem of atherosclerotic cardiovascular diseases (ACCD) in DM, while the manifestations of cardiac arrhythmias (LDC) in conditions of carbohydrate metabolism disorders have not been sufficiently studied.The purpose of the study. To analyze and compare laboratory, instrumental and objective indicators in patients with type 2 diabetes mellitus (type 2 diabetes mellitus) and without, who have a history of cardiac arrhythmias (LDC).Materials and methods. 103 patients with LDC (52 men and 51 women) were examined. 2 groups were formed: the main group – patients with LDC and type 2 diabetes (n=51) (group 1), the control group – patients with LDC without diabetes (n=52) (group 2). A comparative analysis of laboratory-instrumental and clinical-anamnestic data in the groups was performed. Statistical data processing was performed using the statistical software package "Excel" ("Microsoft"), the program "Statistica 10" ("Statsoft Inc"). The value of p <0.05 was taken as the significance level. The reliability of the differences between the groups was determined using the Mann-Whitney U-test, and the correlation analysis was carried out using the Spearman criterion.Results. The average age of the general group was 67[18;97] years, patients with type 2 diabetes 69 [53;93] years, patients without diabetes 65 [18;97] years. According to the performed regression analysis, it was found that DM in patients was associated with the detection of atrial fibrillation (OR 2.69 (95% CI 1.076;6.71), p=0.034), in particular, its constant form (p=0.025, coefficient. Kramer's V = 0.33), as well as with the presence of supraventricular extrasystole (NJES) (OR 0.235 (95%CI 0.09;0.59), p=0.002, coefficient. Kramer's V = 0.311). At the same time, there was no significant association of DM with the presence of paroxysmal and persistent forms of atrial fibrillation, atrial flutter (TP), BLNPG, AV block, CA block, ventricular extrasystole, supraventricular tachycardia (NVT) and SSSI.When evaluating the functional parameters of the myocardium according to Echo-K G data, it was found that in the main group, compared with the control group, significant (34% vs. 27%) and pronounced (18% vs. 6%) pulmonary hypertension were more common, but the difference was not statistically significant (p>0.05).When assessing the structural and geometric parameters of the myocardium, it was found that concentric myocardial hypertrophy was more common in the main group (22% vs. 15%), and in the control group – concentric myocardial remodeling (14% vs. 25%), (p>0.05).Conclusions. DM is a significant risk factor for a more severe course of LDC, in particular atrial fibrillation and supraventricular ectopias. In this regard, it is of fundamental importance to control carbohydrate metabolism and prevent risk factors for cardiovascular diseases in order to preserve the basic functions of the myocardium and improve the quality of life of patients with diabetes mellitus.

Stratification of arrhythmic risk in patients admitted for acute coronary syndrome: the role of the machine learning-derived PRAISE score

Abstract Funding Acknowledgements None. Background Patients with acute coronary syndrome (ACS) have a high arrhythmic burden, and either ventricular and supraventricular arrhythmias are very common during hospitalization[1]. Patients who develop arrhythmias show higher mortality and worse prognosis. The PRAISE (Prediction of Adverse Events Following an Acute Coronary Syndrome) score is a machine-learning based model for predicting 1-year all cause death, recurrent acute myocardial infarction and major bleedings in patients after ACS[2]. To date, its role to predict arrhythmic complications in ACS remains unknown. Purpose We hypothesized that patients with higher PRAISE score have a higher arrhythmic burden. Aim was to evaluate in a prospective protocol the PRAISE score capability for identifying patients with ACS at higher risk of arrhythmic complications during in-hospital stay. Methods A total of 365 consecutive patients admitted to our cardiac intensive care unit for ACS and undergoing percutaneous coronary intervention were enrolled. All patient was monitored by continuous electrocardiogram during hospitalization. The PRAISE score was obtained for each patient <24 hours from admission. Patients were divided into 2 groups based on the results of the PRAISE score for all-cause of death as patients without high PRAISE score (e.g. with low to intermediate risk, n=350) and patients with high PRAISE score (e.g. with high risk, n=15). The occurrence of atrial fibrillation (AF) and ventricular arrhythmias (VAs) up to discharge was recorded. AF was defined by detection of at least one episode of uncoordinated atrial electrical activation and irregular R-R intervals, in absence of distinct repeating P waves and with irregular atrial activations lasting at least 5 minutes. We considered as VAs all episodes of ventricular non-sustained tachycardia, sustained ventricular tachycardia and ventricular fibrillation. Results ROC curve analysis indicated a significant relationship between high PRAISE score and risk of both in-hospital AF (AUC 0.89, 95%CI 0.82-0.94, p=0.0001) and VAs (AUC 0.69, 95%CI 0.64-0.75, p=0.0001). A high PRAISE score had a specificity of 99% for AF and 92% for VAs. By Kaplan-Meier analysis, patients with high PRAISE score more frequently developed AF (30% vs 4% in those without high score; log rank p=0.00001) and VAs (77% vs 35%; log rank p=0.00001). Multivariate analysis showed that a high PRAISE score was an independent predictor of both AF (HR 4.08, 95%CI 1.14-14.58, p=0.030) and VAs (HR 2.36, 95%CI 1.08-5.14, p=0.030). Conclusions In patients hospitalized for ACS, the PRAISE score has a comprehensive capability to identify with high specificity those patients prone to develop arrhythmic events during hospitalization. This may be important in order to stratify patients with higher arrhythmic risk in whom individualized strategies may improve the clinical outcome.Baseline features of the populationKaplan-Meier anaysis

Atrioventricular nodal re-entrant tachycardia with a 2:1 atrioventricular block in a young man: What is the mechanism?

A 16-year-old man presented with short VA supraventricular tachycardia and 2:1 atrioventricular ratio. The correct maneuvers allowed us to guide not only the mechanism but also the probable location of the atrioventricular block.

Application of artificial intelligence in the diagnosis and treatment of cardiac arrhythmia.

The rapid growth in computational power, sensor technology, and wearable devices has provided a solid foundation for all aspects of cardiac arrhythmia care. Artificial intelligence (AI) has been instrumental in bringing about significant changes in the prevention, risk assessment, diagnosis, and treatment of arrhythmia. This review examines the current state of AI in the diagnosis and treatment of atrial fibrillation, supraventricular arrhythmia, ventricular arrhythmia, hereditary channelopathies, and cardiac pacing. Furthermore, ChatGPT, which has gained attention recently, is addressed in this paper along with its potential applications in the field of arrhythmia. Additionally, the accuracy of arrhythmia diagnosis can be improved by identifying electrode misplacement or erroneous swapping of electrode position using AI. Remote monitoring has expanded greatly due to the emergence of contactless monitoring technology as wearable devices continue to develop and flourish. Parallel advances in AI computing power, ChatGPT, availability of large data sets, and more have greatly expanded applications in arrhythmia diagnosis, risk assessment, and treatment. More precise algorithms based on big data, personalized risk assessment, telemedicine and mobile health, smart hardware and wearables, and the exploration of rare or complex types of arrhythmia are the future direction.

Long-term clinical course of patients with catecholaminergic polymorphic ventricular tachycardia: A more than 10-year follow-up cohort study

ABSTRACT Background: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited disorder characterized by ventricular arrhythmias induced by physical or emotional stress. Currently, there are limited data available on the long-term prognosis of CPVT. Methods and Results: In this study, which included both retrospective and prospective components, 12 patients with CPVT (7 males and 5 females) under 18 years old were enrolled to gather and evaluate demographic, clinical, and genetic data. The mean age at diagnosis onset was 7.0 ± 3.1 years. All patients experienced syncope. The mean follow-up duration was 20.1 years. During the follow-up period, all patients experienced at least one episode of supraventricular tachycardia (SVT). Despite beta-blocker therapy, nine patients experienced syncope (75%), and four patients were noncompliant with their treatment. An implantable cardiac defibrillator (ICD) implantation was performed in 10 patients (83%), and among those 5 (50%) experienced appropriate shocks. Inappropriate shocks were observed in all patients with an ICD. The left cardiac sympathetic denervation was performed in 6 patients (50%). One patient died during the follow-up period. Genetic testing was performed in eight patients, five of whom had RYR2 mutations, one patient had mutations in CASQ2, one in TECRL, and one was gene-elusive. Conclusions: The prevalence of cardiac events, even after the initiation of beta-blocker therapy, was found to be distressingly high during long-term follow-up. SVT, such as atrial fibrillation, were found to be more common than previously thought. Combination therapy with a beta-blocker and an IC antiarrhythmic drug shows promise. An individualized approach to the selection of treatment strategies is essential.

Extravascular Implantable Cardioverter-Defibrillator Sensing and Detection in a Large Global Population

BackgroundThe extravascular (EV) implantable cardioverter-defibrillator (ICD) includes features to address sensing and arrhythmia detection challenges presented by its substernal lead location. ObjectivesIn this study, the authors sought to evaluate sensing and detection performance in 299 patients discharged with an EV-ICD in the global pivotal study. MethodsWe reviewed and adjudicated all induced ventricular fibrillation (VF) episodes and spontaneous device-stored episodes that satisfied rate and duration criteria in a programmed ventricular tachycardia (VT)/VF therapy zone. ResultsAt implantation, all EV-ICDs detected induced VF at the programmed sensitivity; 95.9% detected VF with a 3× safety margin. In follow-up, EV-ICDs detected all 59 VT/VF episodes that sustained until therapy. Of 1,034 non-VT/VF episodes, oversensing caused 87.9% and supraventricular tachycardia caused 12.1%. Therapy was withheld in 80.9%, aborted in 10.6%, and delivered in 8.5%. The most common causes of oversensing were myopotentials (61.2%) and P-wave oversensing (PWOS) (19.9%). Inappropriate shocks occurred in only 3.2% of myopotential episodes, but in 21.8% of PWOS episodes. Myopotential oversensing was more common with Ring-Can sensing (P < 0.0001) and correlated with low R-wave amplitude (P < 0.0001). PWOS occurred almost exclusively with Ring1-Ring2 sensing (P = 0.0001) and began with transient decrease in R-wave or increase in P-wave amplitude (P < 0.0001). In software emulation, a new PWOS discriminator significantly reduced total inappropriate detections. ConclusionsIn a global population, EV-ICD detected induced and spontaneous VT/VF accurately. Although discriminators withheld detection from most non-VT/VF episodes, inappropriate shocks were common. The most common cause was PWOS, which may be reduced by optimizing sensing at implantation and incorporation of the PWOS discriminator, which is now in the current device. (Extravascular ICD Pivotal Study [EV ICD]; NCT04060680)

Coronary Sinus Metabolite 12,13-diHOME Is a Novel Biomarker for Left Atrial Remodeling in Patients With Atrial Fibrillation.

12,13-dihydroxy-9Z-octadecenoic acid (12,13-diHOME) has shown potential in protecting against heart disease, but its relationship with atrial fibrillation (AF) remains unknown. Coronary sinus (CS) and femoral vein blood samplings were synchronously collected from AF and non-AF subjects (paroxysmal supraventricular tachycardia or idiopathic premature ventricular complexes) who underwent catheter ablation. First, untargeted metabolomic profiling was performed in a discovery cohort (including 12 AF and 12 non-AF subjects) to identify the most promising CS or femoral vein metabolite. Then, the selected metabolite was further measured in a validation cohort (including 119 AF and 103 non-AF subjects) to confirm its relationship with left atrium remodeling and 1-year postablation recurrence of AF. Finally, the biological function of the selected metabolite was validated in a rapid-paced cultured HL-1 atrial cardiomyocytes model. Metabolomic analysis identified CS 12,13-diHOME as the most pronounced change metabolite correlated with left atrium remodeling in the discovery cohort. In the validation cohort, CS 12,13-diHOME was significantly lower in patients with AF than non-AF controls (84.32±20.13 versus 96.24±23.56 pg/mL; P<0.01), and associated with worse structural, functional, and electrical remodeling of left atrium. Multivariable regression analyses further demonstrated that decreased CS 12,13-diHOME was an independent predictor of 1-year postablation recurrence of AF (odds ratio, 0.754 [95% CI, 0.648-0.920]; P=0.005). Biological function validations showed that 12,13-diHOME treatment significantly protect the cell viability, improved the expression of MHC (myosin heavy chain) and Cav1.2 (L-type calcium channel α1c), and attenuated mitochondrial damage in the rapid-paced cultured HL-1 cardiomyocytes model. CS metabolite 12,13-diHOME is decreased in patients with AF and can serve as a novel biomarker for left atrium remodeling.

Fetal premature atrial contractions: natural course, risk factors and adverse outcome.

Fetal premature atrial contractions (PAC) are usually benign but may be associated with congenital heart defect (CHD) and tachyarrhythmia, which in turn carry a risk of cardiac failure and fetal death. We aimed to explore the frequency of adverse outcome and to identify risk factors for tachyarrhythmia in pregnancies complicated by fetal PAC. This was a retrospective cohort study of fetuses diagnosed with PAC at two academic centers in Amsterdam, The Netherlands, between 2007 and 2022. Cases with a congenital anomaly and those with a prior diagnosis of CHD or other arrhythmias were excluded. M-mode and Doppler tracings were reanalyzed and the frequency of PAC was recorded. The incidence of the following adverse outcomes was examined: underlying CHD not identified at the 20-week fetal anomaly scan, tachyarrhythmia, other arrhythmia, administration of antiarrhythmic therapy and death. Risk factors for tachyarrhythmia were analyzed using odds ratios (OR). In 24.1% of 1439 referred cases, PAC resolved before confirmation at the fetal medicine unit (FMU). Of the 939 included cases with confirmed PAC, the total incidence of adverse outcome was 6.8% (64/939). CHD was diagnosed in 14 (1.5% (95% CI, 0.9-2.5%)) cases, of which eight were diagnosed prenatally and six postnatally. Compared with baseline, the incidence of CHD was higher in the presence of fetal PAC (OR, 1.8 (95% CI, 1.0-3.3); P = 0.034). Tachyarrhythmia occurred prenatally and/or postnatally in 32 (3.4%) cases, of which eight (25.0%) showed signs of cardiac failure, and in 23 (71.9%) cases, antiarrhythmic therapy was required. No cases of tachyarrhythmia led to fetal or infant death. Risk factors for tachyarrhythmia were PAC with short runs of supraventricular tachycardia (OR, 98.7), blocked PAC (OR, 30.3), PAC in bigeminy (OR, 21.8), frequent PAC (one per 5-10 beats) (OR, 6.9), signs of cardiac failure (OR, 14.2) and the presence of a foramen ovale aneurysm (OR, 5.0). PAC are generally benign and often resolve spontaneously. However, fetuses with an irregular heart rhythm should be referred for advanced ultrasonography, which should focus on classifying the type of PAC and risk of adverse outcome. When risk factors for tachyarrhythmia are identified, weekly fetal heart-rate monitoring is advised until resolution of the PAC. In the absence of risk factors, standard obstetric care may be sufficient, with additional instructions to report reduced fetal movements. Should tachyarrhythmia or cardiac failure develop, referral back to the FMU is indicated. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

THE IMPORTANCE OF CARDIAC MAGNETIC RESONANCE IMAGING IN THE ASSESSMENT OF THE RISK OF CARDIAC ARRHYTHMIAS IN PATIENTS WITH ARTERIAL HYPERTENSION

Objective: Arterial hypertension leads to organ changes, including left ventricular hypertrophy. The increased mass of left ventricle increases the risk of cardiac arrhythmias, which enhances the risk of sudden cardiac death. Cardiac magnetic resonance imaging (CMRI) can identify the presence of myocardial fibrosis by assessing late gadolinium enhancement (LGE). The aim of the study was to assess the relationship between the presence of late gadolinium enhancement at the right ventricular insertion point (RVIP) determined by CMRI and the occurrence of cardiac arrhythmias in patients with arterial hypertension. Design and method: 30 patients with essential hypertension were qualified for the study, 18 men and 12 women, the average age of the subjects was 55.5 ± 12.4 years. All subjects underwent cardiac magnetic resonance imaging and 24-hour Holter ECG monitoring. Based on the presence of LGE at the right ventricular insertion point, assessed by CMRI, the subjects were divided into two subgroups. The first subgroup consisted of subjects with LGE at the right ventricular insertion point (RVIP + subgroup), while the second subgroup consisted of subjects without LGE at the right ventricular insertion point (RVIP - subgroup). Results: Subjects with LGE at the right ventricular insertion point were characterized by higher maximum and minimum heart rates in 24-hour Holter ECG recordings compared to subjects without LGE at the right ventricular insertion point (p &lt; 0.05). In subjects with LGE at the right ventricular insertion point, Holter ECG evaluation revealed a statistically significantly higher number of single premature supraventricular beats, single premature ventricular beats and supraventricular tachycardias compared to subjects without LGE at the right ventricular insertion point (p &lt; 0.05). The regression analysis performed showed that a longer time from the diagnosis of hypertension and the occurrence of LGE at the right ventricular insertion point assessed using CMRI are independent risk factors for cardiac arrhythmias (p &lt; 0.05). Conclusions: Cardiac magnetic resonance imaging by identifying of late gadolinium enhancement at the right ventricular insertion point may be a useful diagnostic method in assessing the risk of cardiac arrhythmias in a group of patients with arterial hypertension.

ANALYSIS OF THE FREQUENCY AND STRUCTURE OF HOSPITALIZATION OF YOUNG PATIENTS IN A CARDIOLOGY HOSPITAL IN ALMATY

Objective: To study the frequency and structure of hospitalizations of young patients (up to 44 years old, WHO) at the Almaty City Cardiology Center for the period 2018–2022. Design and method: In the course of an observational, descriptive, cross-sectional study, we studied the frequency and structure of reasons for hospitalization in young patients over a five-year period. Results: During the study, it was found that during the designated period, a total of 1827 young patients were hospitalized (average age 36.7 ± 4.4 years), which amounted to 4.8% of the total number of hospitalized patients (n = 38054). Detailing by year, it should be noted that the peak of hospitalizations occurred in 2019 - 8.5%, with a significant decrease in 2020 - 4%, (which may have been due to the COVID-SARS-2 pandemic), while the minimum was recorded in 2018 - 3%. The most common cause of hospitalization (more than 30%) were acute forms of coronary heart disease, while the frequency of hospitalization with unstable angina (23.5%) prevailed over the myocardial infarction (12.2%). The third position was occupied by arterial hypertension - 9.9%. In descending order, the following nosologies followed: cardiomyopathies - 8.1% and acute myocarditis - 5.6%. The top ten most common reasons for hospitalization also included supraventricular tachycardia, atrial fibrillation/flutter, WPW syndrome. Analysis of the frequency of hospitalizations of patients with acute forms of coronary heart disease over the years demonstrated an upward trend. Among all hospitalizations of young patients with myocardial infarction, the most common was, according to the ICD-11 code (I21.0) -42.8%, then in descending order - (I21.1) -25.7%, (I21.4) -12.2%, (I22.1) -7.2%, (I22.0) -6.8% (I22.8) -2.3%. Conclusions: Thus, among all reasons for hospitalization, unstable angina, myocardial infarction and arterial hypertension occupied the three leading positions. Dynamics of the frequency of hospitalization of young patients with acute forms of coronary heart disease had an upward trend. The most common type of myocardial infarction in young people was acute transmural myocardial infarction of the left ventricle, which probably determines the severity of myocardial damage and the unfavorable prognosis in this population.

Stimuli factor of muscular receptors, extraocular muscles and oculocardiac reflex (OCR)

Introduction: The oculocardiac reflex (OCR) was first described in 1908 as a reduction in heart rate secondary to direct pressure on the eyeball. OCR has been described during ophthalmologic procedures. This is also a standard test for peripherical autonomic and vagal system with the diving reflex and overtraining. The aim studied the specificities of stimuli of stretch receptors wich can be the traction at the extraocular muscles. Materials: 7 rabbits were included on the study. The anesthesia was done by an Intraperitoneal administration of ethyl carbamate. During all the study the rabbit is immobilized with a gripping frame for the head. Heart rate and RR were measured with EKG was recorded online. Methods: Bilateral pressure is applied using a mechanical pressure compression device, ranging from 100 to 800 mmHg, either instantaneously or in 15 or 30 seconds. For each pression we studied the variations of the RRspace (RRmax and RRt function of time) compared with the RRcontrol. If no variation, RRmax/RRcontrol and RRt/RRcontrol =1 Results: Response to abrupt compression RRmax varied linearly and significantly with pression. Response to progressive compression did not show any significant variation either during rise of pressure or when pressure was reached. Time-based response was studied from 56RR intervals. With abrut compression, the increase was effective from the first or second RR intervals. Depending on the pressure, it increased up to the 20th, presented a peak and decreased even with maintained pressure. The RR interval reverted to the control (RR/tRR = 1) around the 40th interval. With progressive stimulation, the maximum elongation value is lower, with an identical decay. Discussion: Our work showed the characteristics of stimulating factor: we used pressure on eyeballs, as in a sports medicine test (cardiac parasympathetic analysis) and in emergencies for the reduction of arrhythmias. This principal factor is tension in function of time, with an elongation of the periorbital muscles and the neuromuscular spindle. This is a proprioceptive sensory mecano-receptor sensitive to elongation. It is made up of primary neuromuscular fibers known as nuclear sac fibers and secondary neuromuscular fibers known as nuclear chain fibers. The former are 'phasic' (i.e. reacting to a variation in tension) and the latter 'tonic' (i.e. reacting directly to tension). Our work showed that the neuromuscular fibers of the nuclear sac type are stimulated by variations in tension as a function of time. Platen (1961) in ocular surgery introduced the notion of traction on the oculomotor muscles. In ‘OpenAnesthesia 2023’ Dennath Chatterjee did a synthesis work in the traction and anesthesia factors. In sports medicine, the dive reflex has been shown to be responsable of arythmia and paroxysmal supraventricular tachycardia. To trigger this reflex, several tests have beeen proposed. A recommandation during clinical examination is the OCR or Carotid glomus massage, with record of EKG and cardiac frequency. Conclusion: The OCR is defined by a reduction in heart rate from direct pressure on the eyeball. Afferent and efferent pathways are known and studied. But the stimulating factor must be studied. We have demontred that is the elongation of neuro-muscular fibers according to the time that excites the phasic fibers. This notion must be integrated both in eye surgery and in tests to highlight the cardiac parasympathetic balance, especially in sports physiology. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Detection of Arrhythmias Using Smartwatches-A Systematic Literature Review.

Smartwatches represent one of the most widely adopted technological innovations among wearable devices. Their evolution has equipped them with an increasing array of features, including the capability to record an electrocardiogram. This functionality allows users to detect potential arrhythmias, enabling prompt intervention or monitoring of existing arrhythmias, such as atrial fibrillation. In our research, we aimed to compile case reports, case series, and cohort studies from the Web of Science, PubMed, Scopus, and Embase databases published until 1 August 2023. The search employed keywords such as "Smart Watch", "Apple Watch", "Samsung Gear", "Samsung Galaxy Watch", "Google Pixel Watch", "Fitbit", "Huawei Watch", "Withings", "Garmin", "Atrial Fibrillation", "Supraventricular Tachycardia", "Cardiac Arrhythmia", "Ventricular Tachycardia", "Atrioventricular Nodal Reentrant Tachycardia", "Atrioventricular Reentrant Tachycardia", "Heart Block", "Atrial Flutter", "Ectopic Atrial Tachycardia", and "Bradyarrhythmia." We obtained a total of 758 results, from which we selected 57 articles, including 33 case reports and case series, as well as 24 cohort studies. Most of the scientific works focused on atrial fibrillation, which is often detected using Apple Watches. Nevertheless, we also included articles investigating arrhythmias with the potential for circulatory collapse without immediate intervention. This systematic literature review provides a comprehensive overview of the current state of research on arrhythmia detection using smartwatches. Through further research, it may be possible to develop a care protocol that integrates arrhythmias recorded by smartwatches, allowing for timely access to appropriate medical care for patients. Additionally, continuous monitoring of existing arrhythmias using smartwatches could facilitate the assessment of the effectiveness of prescribed therapies.

Clinical Significance of Supraventricular Tachycardia During Pregnancy in Healthy Women

BackgroundSupraventricular tachycardias (SVT) are the most frequently encountered arrhythmias in pregnancy with unclear clinical significance. ObjectivesThis study sought to report the prevalence, describe the management, and explore the association between SVT and adverse obstetric outcomes. MethodsCohort study of primiparous and multiparous women without history of Cesarean section (CS), and with structurally normal hearts admitted in labor. The study group consisted of women with at least 1 SVT episode during pregnancy, and the control group was randomly selected in a 4:1 ratio. ResultsOf 141,769 women meeting the inclusion criteria, SVT diagnosis was confirmed in 122. A total of 76 (age 33.2 ± 4.8 years) had at least 1 symptomatic and documented episode during pregnancy. In women with a known SVT diagnosis before pregnancy, medical therapy was not associated with a lower risk of SVT recurrence (OR: 1.07; 95% CI: 0.41-2.80). However, catheter ablation before pregnancy was associated with significantly lower risk of SVT recurrence (OR: 0.09; 95% CI: 0.04-0.23). Women with SVT during pregnancy had higher incidence of CS (39.5% vs 27.0%; P = 0.03), and preterm labor (PTL) (30.3% vs 8.6%; P < 0.001). Adjusting for age and parity, SVT during pregnancy was an independent predictor of CS (OR: 1.80; 95% CI: 1.03-3.10), particularly planned CS (OR: 2.89; 95% CI: 1.06-7.89) and PTL (OR: 4.37; 95% CI: 2.30-8.31). ConclusionsSVT during pregnancy is associated with increased risk for CS and PTL in healthy women. History of SVT should be sought as early as preconception counseling, and a multidisciplinary approach is warranted for both prevention and management of SVT occurrence.

Associations of Atrioventricular Blocks and Other Arrhythmias in Patients with Lyme Carditis: A Systematic Review and Meta-Analysis.

Lyme disease often leads to cardiac injury and electrophysiological abnormalities. This study aimed to explore links between atrioventricular blocks and additional arrhythmias in Lyme carditis patients. This systematic review and meta-analysis of existing literature was performed from 1990 to 2023, and aimed to identify cases of Lyme carditis through serology or clinical diagnosis with concomitant arrhythmias. Pubmed and Web of Science were searched using appropriate MESH terms. Patients were divided into groups with atrioventricular blocks and other arrhythmias for cardiovascular (CV) outcome assessment. A total of 110 cases were analyzed. The majority (77.3%) were male, with mean age = 39.65 ± 14.80 years. Most patients presented within one week of symptom onset (30.9%). Men were more likely to have first-degree atrioventricular blocks (OR = 1.36 [95% CI 1.12-3.96], p = 0.01); these blocks tended to be reversible in nature (OR = 1.51 [95% CI 1.39-3.92], p = 0.01). Men exhibited a higher likelihood of experiencing variable arrhythmias (OR = 1.31 [95% CI 1.08-2.16], p < 0.001). Ventricular and supraventricular arrhythmias were more likely to exhibit instability (OR = 0.96 [95% CI 0.81-1.16] p = 0.01) and variability (OR = 1.99 [95% CI 0.47-8.31], p < 0.001). Men with Lyme carditis are likely to present with various atrioventricular blocks. These atrioventricular blocks are benign, and follow a predictable and stable clinical course. Further large-scale studies are warranted to confirm these associations.

Comparative utility of omnipolar and bipolar electroanatomic mapping methods to detect and localize dual nodal substrate in patients with atrioventricular nodal reentrant tachycardia.

Catheter-based slow pathway modification (SPM) for atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed at empiric sites using anatomical landmarks and test ablation feedback within the triangle of Koch (TK). While studies have described more tailored techniques such as bipolar low voltage bridge (LVB) and wavefront collision identification, few have systematically compared the diagnostic yields of each and none have investigated whether omnipolar mapping technology provides incremental benefit. The objective of this study was to compare the utility of omnipolar andbipolar-derived qualitative and quantitative measurements in identifying and localizing dual AVN substrate in patients with versus without AVNRT. A retrospective case-control study of consecutive patients with paroxysmal supraventricular tachycardia undergoing electrophysiology study with both omnipolar and bipolar mapping from 2022-2023. Thirteen AVNRT cases (median age 16.1 years, 512 TK points) were compared to nine non-AVNRT controls (median age 15.7 years, 332 TK points). Among qualitative variables, an omnipolar activation vector pivot, defined as a ≥45 degree change in activation direction within the TK, had the highest positive (81%) and negative predictive values (100%) for identifying AVNRT cases and had a median distance of 1 mm from SPM sites. Among quantitative variables, the optimal discriminatory performance for successful SPM sites was observed using bipolar voltage restricted to a peak frequency >340 Hz (c statistic 0.75). Omnipolar vector pivot analysis represents an automated, annotation-independent qualitative technique that is sensitive and specific for AVNRT substrate and co-localizes with successful SPM sites. Bipolar voltage quantitatively describes SP anisotropy better than omnipolar voltage, and the addition of peak frequency signal analysis further optimizes the selection of SPM sites.

A Prospective Study on Deep Inspiration Breath Hold Thoracic Radiation Therapy Guided by Bronchoscopically Implanted Electromagnetic Transponders.

Electromagnetic transponders bronchoscopically implanted near the tumor can be used to monitor deep inspiration breath hold (DIBH) for thoracic radiation therapy (RT). The feasibility and safety of this approach require further study. We enrolled patients with primary lung cancer or lung metastases. Three transponders were implanted near the tumor, followed by simulation with DIBH, free breathing, and 4D-CT as backup. The initial gating window for treatment was ±5 mm; in a second cohort, the window was incrementally reduced to determine the smallest feasible gating window. The primary endpoint was feasibility, defined as completion of RT using transponder-guided DIBH. Patients were followed for assessment of transponder- and RT-related toxicity. We enrolled 48 patients (35 with primary lung cancer and 13 with lung metastases). The median distance of transponders to tumor was 1.6 cm (IQR 0.6-2.8 cm). RT delivery ranged from 3 to 35 fractions. Transponder-guided DIBH was feasible in all but two patients (96% feasible), where it failed because the distance between the transponders and the antenna was >19 cm. Among the remaining 46 patients, 6 were treated prone to keep the transponders within 19 cm of the antenna, and 40 were treated supine. The smallest feasible gating window was identified as ±3 mm. Thirty-nine (85%) patients completed one year of follow-up. Toxicities at least possibly related to transponders or the implantation procedure were grade 2 in six patients (six incidences, cough and hemoptysis), grade 3 in three patients (five incidences, cough, dyspnea, pneumonia, and supraventricular tachycardia), and grade 4 pneumonia in one patient (occurring a few days after implantation but recovered fully and completed RT). Toxicities at least possibly related to RT were grade 2 in 18 patients (41 incidences, most commonly cough, fatigue, and pneumonitis) and grade 3 in four patients (seven incidences, most commonly pneumonia), and no patients had grade 4 or higher toxicity. Bronchoscopically implanted electromagnetic transponder-guided DIBH lung RT is feasible and safe, allowing for precise tumor targeting and reduced normal tissue exposure. Transponder-antenna distance was the most common challenge due to a limited antenna range, which could sometimes be circumvented by prone positioning.

Mortality and rehospitalization in patients with pre-existing implantable pacemakers undergoing catheter ablation are related to increased comorbidity burden-data from the German Ablation Registry.

Catheter ablation of atrial fibrillation and atrial flutter is routinely performed in patients with implantable devices. The aim of the present study was to assess success rates and potential complications in a large registry cohort of patients with cardiac pacemakers. The German Ablation Registry is a nationwide, prospective registry with a 1-year follow-up investigating patients who underwent catheter ablation of supraventricular arrhythmias in 51 German centers. The present analysis focussed on the presence of cardiac pacemakers in 591 patients undergoing catheter ablation of atrial fibrillation or atrial flutter. These were compared to 7393 patients without a pacemaker. Patients with pacemakers were significantly older and presented more comorbidities like diabetes, renal failure, cardiovascular disease, or previous stroke. One-year mortality (2.4% vs. 1.3%, p = 0.022) and a combined endpoint of death, myocardial infarction, and stroke (3.6% vs. 2.1%, p = 0.014) were significantly elevated in patients with pacemakers. Re-hospitalization was also more common in patients with a pacemaker (53.3% vs. 45.0%, p < 0.01). After adjustment for important comorbidities, pre-existing pacemaker systems did not show any negative effect. Procedural success was reported in 98.8% vs. 98.4% (p = 0.93). Device-related complications were only observed in 0.4% of patients with pacemakers. Patients with pacemaker systems undergoing catheter ablation of atrial fibrillation or atrial flutter demonstrate an increased risk of death, cardiovascular events, and re-hospitalization. This observation can be largely attributed to an older patient population and an increased rate of comorbidities.

Supraventricular tachycardia with a variable RP relationship but without a change in the cycle length: What is the mechanism?

Supraventricular tachycardia with a variable RP relationship but without a change in the cycle length: What is the mechanism?

Interpreting Wide-Complex Tachycardia With the Use of Artificial Intelligence

BackgroundAdopting artificial intelligence (AI) in medicine may improve speed and accuracy in patient diagnosis. We sought to develop an AI algorithm to interpret wide-complex tachycardia (WCT) electrocardiograms (ECGs) and compare its diagnostic accuracy with that of cardiologists. MethodsUsing 3330 WCT ECGs (2906 supraventricular tachycardia [SVT] and 424 ventricular tachycardia [VT]), we created a training/validation (3131) and a test set (199 ECGs). A convolutional neural network structure using a modification of differentiable architecture search was developed to differentiate between SVT and VT. ResultsThe mean accuracy of electrophysiology (EP) cardiologists was 92.5% with sensitivity 91.7%, specificity 93.4%, positive predictive value 93.7%, and negative predictive value 91.7%. Non-EP cardiologists had an accuracy of 73.2 ± 14.4% with sensitivity, specificity, and positive and negative predictive values of 59.8 ± 18.2%, 93.8 ± 3.7%, 93.6 ± 2.3%, and 73.2 ± 14.4%, respectively. AI had superior sensitivity and accuracy (91.9% and 93.0%, respectively) than non-EP cardiologists and similar performance compared with EP cardiologists. Mean time to interpret each ECG varied from 10.1 to 13.8 seconds for EP cardiologists and from 3.1 to 16.6 seconds for non-EP cardiologists. AI required a mean of 0.0092 ± 0.0035 seconds for each ECG interpretation. ConclusionsAI appears to diagnose WCT with accuracy superior to non-EP cardiologists and similar to EP cardiologists. Using AI to assist with ECG interpretations may improve patient care.