Ventricular Activation Research Articles

A novel automated peak frequency annotation algorithm for identifying deceleration zones and ventricular tachycardia ablation sites

BackgroundCurrent annotation of local fractionated signals during ventricular electroanatomic mapping (EAM) requires manual input subject to variability and error. ObjectivesThe purpose of this study was to evaluate a novel peak frequency (PF) annotation software for its ability to automatically detect late potentials (LPs) and local abnormal ventricular activity (LAVA), determine an optimal range for display, and assess its impact on isochronal late activation mapping (ILAM). MethodsEAM data from 25 patients who underwent ventricular tachycardia (VT) ablation were retrospectively analyzed. Samplings of electrogram PFs from areas of normal bipolar voltage, areas of low voltage, and areas of low voltage with fractioned signals were performed. An optimal range of frequency display was identified from these patients and applied to a validation cohort of 10 prospective patients to assess high PF within scar as a predictor of VT ablation target sites, in particular deceleration zones (DZs) identified by ILAM, LP, and LAVA. ResultsVoltage and PF ranges of normal endocardial tissue varied widely. Using 220 Hz as a frequency cutoff value in areas of low bipolar voltage, areas of high fractionation were identified with sensitivity of 91% and specificity of 85% There was no significant reduction in targeted DZ surface areas, and colocalization with DZs was observed in all cases. Applied to the prospective cohort, PF predicted fractionated areas and DZ in 9 of 10 patients. ConclusionA PF annotation algorithm with a cutoff of 220 Hz accurately identifies areas of fractioned signals and accurately predicts DZs during ILAM.

Differences in ventricular wall composition may explain inter-patient variability in the ECG response to variations in serum potassium and calcium.

Objective: Chronic kidney disease patients have a decreased ability to maintain normal electrolyte concentrations in their blood, which increases the risk for ventricular arrhythmias and sudden cardiac death. Non-invasive monitoring of serum potassium and calcium concentration, [K+] and [Ca2+], can help to prevent arrhythmias in these patients. Electrocardiogram (ECG) markers that significantly correlate with [K+] and [Ca2+] have been proposed, but these relations are highly variable between patients. We hypothesized that inter-individual differences in cell type distribution across the ventricular wall can help to explain this variability. Methods: A population of human heart-torso models were built with different proportions of endocardial, midmyocardial and epicardial cells. Propagation of ventricular electrical activity was described by a reaction-diffusion model, with modified Ten Tusscher-Panfilov dynamics. [K+] and [Ca2+] were varied individually and in combination. Twelve-lead ECGs were simulated and the width, amplitude and morphological variability of T waves and QRS complexes were quantified. Results were compared to measurements from 29 end-stage renal disease (ESRD) patients undergoing hemodialysis (HD). Results: Both simulations and patients data showed that most of the analyzed T wave and QRS complex markers correlated strongly with [K+] (absolute median Pearson correlation coefficients, r, ranging from 0.68 to 0.98) and [Ca2+] (ranging from 0.70 to 0.98). The same sign and similar magnitude of median r was observed in the simulations and the patients. Different cell type distributions in the ventricular wall led to variability in ECG markers that was accentuated at high [K+] and low [Ca2+], in agreement with the larger variability between patients measured at the onset of HD. The simulated ECG variability explained part of the measured inter-patient variability. Conclusion: Changes in ECG markers were similarly related to [K+] and [Ca2+] variations in our models and in the ESRD patients. The high inter-patient ECG variability may be explained by variations in cell type distribution across the ventricular wall, with high sensitivity to variations in the proportion of epicardial cells. Significance: Differences in ventricular wall composition help to explain inter-patient variability in ECG response to [K+] and [Ca2+]. This finding can be used to improve serum electrolyte monitoring in ESRD patients.

Outcomes of left bundle branch area pacing compared to His bundle pacing as a primary pacing strategy: Systematic review and meta-analysis.

Novel pacing technologies, such as His bundle pacing (HBP) and left bundle branch area pacing (LBBaP), have emerged to maintain physiological ventricular activation. We investigated the outcomes of LBBP with HBP for patients requiring a de novo permanent pacing. Systematic review of randomized clinical trials and observational studies comparing LBBaP with HBP until March 01, 2023 was performed. Random and fixed effects meta-analyses of the effect of pacing technology on outcomes were performed. Study outcomes included pacing metrics, QRS duration, lead revision, procedure parameters, all-cause mortality and heart failure hospitalization (HFH). Overall, 10 studies with 1596 patients were included. Implant success rate was higher in LBBaP compared with HBP (RR 1.24, 95% CI: 1.08 to 1.42, p=.002). LBBaP was associated with lower capture threshold at implantation (mean difference (MD) -0.62V, 95% CI: -0.74 to -0.51V, p<.0001) and at follow-up (MD -0.74V, 95% CI: -0.96 to -0.53, p<.0001), shorter procedure duration (MD -14.66min, 95% CI: -23.54 to -5.78, p=.001) and shorter fluoroscopy time (MD -4.2min, 95% CI: -8.4 to -0.0, p=.05). Compared with HBP, LBBaP was associated with a decreased risk of all-cause mortality (RR: 0.50, 95% CI: 0.33 to 0.77, p=.002) and HFH (RR: 0.57, 95% CI: 0.33 to 1.00, p=.05). No statistical differences were found in lead revisions and QRS duration before and after pacing. This meta-analysis found that LBBaP was superior to HBP regarding pacing metrics and implant success rate as an initial pacing strategy, although absence of head-to-head randomized comparison warrants caution in interpretation of the results.

Left bundle branch pacing with and without anodal capture: impact on ventricular activation pattern and acute haemodynamics.

Left bundle branch pacing (LBBP) can deliver physiological left ventricular activation, but typically at the cost of delayed right ventricular (RV) activation. Right ventricular activation can be advanced through anodal capture, but there is uncertainty regarding the mechanism by which this is achieved, and it is not known whether this produces haemodynamic benefit. We recruited patients with LBBP leads in whom anodal capture eliminated the terminal R-wave in lead V1. Ventricular activation pattern, timing, and high-precision acute haemodynamic response were studied during LBBP with and without anodal capture. We recruited 21 patients with a mean age of 67 years, of whom 14 were males. We measured electrocardiogram timings and haemodynamics in all patients, and in 16, we also performed non-invasive mapping. Ventricular epicardial propagation maps demonstrated that RV septal myocardial capture, rather than right bundle capture, was the mechanism for earlier RV activation. With anodal capture, QRS duration and total ventricular activation times were shorter (116 ± 12 vs. 129 ± 14 ms, P < 0.01 and 83 ± 18 vs. 90 ± 15 ms, P = 0.01). This required higher outputs (3.6 ± 1.9 vs. 0.6 ± 0.2 V, P < 0.01) but without additional haemodynamic benefit (mean difference -0.2 ± 3.8 mmHg compared with pacing without anodal capture, P = 0.2). Left bundle branch pacing with anodal capture advances RV activation by stimulating the RV septal myocardium. However, this requires higher outputs and does not improve acute haemodynamics. Aiming for anodal capture may therefore not be necessary.

Localized cardiomyocyte lipid accumulation is associated with slowed epicardial conduction in rats.

Transmural action potential duration differences and transmural conduction gradients aid the synchronization of left ventricular repolarization, reducing vulnerability to transmural reentry and arrhythmias. A high-fat diet and the associated accumulation of pericardial adipose tissue are linked with conduction slowing and greater arrhythmia vulnerability. It is predicted that cardiac adiposity may more readily influence epicardial conduction (versus endocardial) and disrupt normal transmural activation/repolarization gradients. The aim of this investigation was to determine whether transmural conduction gradients are modified in a rat model of pericardial adiposity. Adult Sprague-Dawley rats were fed control/high-fat diets for 15 wk. Left ventricular 300 µm tangential slices were generated from the endocardium to the epicardium, and conduction was mapped using microelectrode arrays. Slices were then histologically processed to assess fibrosis and cardiomyocyte lipid status. Conduction velocity was significantly greater in epicardial versus endocardial slices in control rats, supporting the concept of a transmural conduction gradient. High-fat diet feeding increased pericardial adiposity and abolished the transmural conduction gradient. Slowed epicardial conduction in epicardial slices strongly correlated with an increase in cardiomyocyte lipid content, but not fibrosis. The positive transmural conduction gradient reported here represents a physiological property of the ventricular activation sequence that likely protects against reentry. The absence of this gradient, secondary to conduction slowing and cardiomyocyte lipid accumulation, specifically in the epicardium, indicates a novel mechanism by which pericardial adiposity may exacerbate ventricular arrhythmias.

Optimization of A 12-lead ECG subset for Automated Early Left-Ventricular Activation Localization Approach based on Pace-Mapping Technology.

We previously developed an automated approach based on pace-mapping to localize early left-ventricular (LV) activation origin. To avoid a singular system, we require pacing from at least 2 more known sites than the number of ECG leads used. Fewer leads used means fewer pacing sites required. To identify an optimal minimal ECG-lead set for the automated approach. We used 1715 LV endocardial pacing sites to create derivation and testing datasets. The derivation dataset, consisting of 1012 known pacing sites pooled from 38 patients, was used to identify an optimal 3-lead set using random-forest regression (RFR), and a second 3-lead set using exhaustive search. The performance of these sets and the calculated Frank leads was compared within the testing dataset with 703 pacing sites pooled from 25 patients. The RFR yielded III, V1, and V4, while the exhaustive search identified leads II, V2 and V6. Comparison of these sets and the calculated Frank leads demonstrated similar performance when utilizing ≥ 5 known pacing sites. Accuracy improved with additional pacing sites, achieving mean accuracy of < 5 mm, after including up to 9 pacing sites when they were focused on a suspect area of ventricular activation origin (radius < 10 mm). The RFR identified the quasi-orthogonal leads set to localize the source of LV activation, minimizing the training set of pacing sites. Localization accuracy was high using these leads, and was not significantly different from using leads identified by exhaustive search, or empiric use of Frank leads.

Conduction system pacing: how far are we from the "electrical" bypass?

Conduction system pacing is an alternative practice to conventional right ventricular apical pacing. It is a method that maintains physiologic ventricular activation, based on a correct pathophysiological basis, in which the pacing lead bypasses the lesion of the electrical fibers and the electrical impulse transmits through the intact adjacent conduction system. For this reason, it might be reasonably characterized by the term "electrical bypass" compared to the coronary artery bypass in revascularization therapy. In this review, reference is made to the sequence of events in which conventional right ventricular pacing may cause adverse outcomes. Furthermore, there is a reference to alternative strategies and pacing sites. Interest focuses on the modalities for which there are data from the literature, namely for the right ventricular (RV) septal pacing, the His bundle pacing (HBP), and the left bundle branch pacing (LBBP). A more extensive reference is about the HBP, for which there are the most updated data. We analyze the considerations that limit HBP-wide application in three axes, and we also present the data for the implantation and follow-up of these patients. The indications with their most important studies to date are then described in detail, not only in their undoubtedly positive findings but also in their weak aspects, because of which this pacing mode has not yet received a strong recommendation for implementation. Finally, there is a report on LBBP, focusing mainly on its points of differentiation from HBP.

Conduction System Pacing versus Conventional Biventricular Pacing for Cardiac Resynchronization Therapy: Where Are We Heading?

Over the last few years, pacing of the conduction system (CSP) has emerged as the new standard pacing modality for bradycardia indications, allowing a more physiological ventricular activation compared to conventional right ventricular pacing. CSP has also emerged as an alternative modality to conventional biventricular pacing for the delivery of cardiac resynchronization therapy (CRT) in heart failure patients. However, if the initial clinical data seem to support this new physiological-based approach to CRT, the lack of large randomized studies confirming these preliminary results prevents CSP from being used routinely in clinical practice. Furthermore, concerns are still present regarding the long-term performance of pacing leads when employed for CSP, as well as their extractability. In this review article, we provide the state-of-the-art of CSP as an alternative to biventricular pacing for CRT delivery in heart failure patients. In particular, we describe the physiological concepts supporting this approach and we discuss the future perspectives of CSP in this context according to the implant techniques (His bundle pacing and left bundle branch area pacing) and the clinical data published so far.

Cardiopulmonary resuscitation: the power to save lives

Cardiopulmonary arrest (CPA) is understood as the sudden, unexpected and catastrophic cessation of systemic circulation, useful ventricular and ventilatory activity. It is essential that any individual is aware of the risk factors, epidemiology, has minimal knowledge to recognize a CPA early and can proceed appropriately to provide quality support to the victim. The advances in terms of technology, treatment and prevention are notorious, however, many lives are still lost due to the poor quality of a first care. The study aimed to understand the level of knowledge and train the population about risk factors, epidemiology, early recognition, correct initial approach, cardiac compressions and quality ventilation, in order to reduce the incidence of mortality and improve the prognosis of patients in cardiac arrest. An exploratory intervention was used, bringing knowledge objectively, through banners, folders and lectures in easy-to-understand language, providing quality and relevant information so that listeners could acquire indispensable skills and actually change lives. The actions took place in a Basic Health Unit (BHU), on previously established days and times, always striving to reach as many people as possible. Recognizing early and knowing how to conduct a CPA until specialized help arrives is of fundamental importance, but unfortunately the largest part of the population approached demonstrated to be unaware of the basics on the subject. Unpreparedness regarding risk factors, initial signs and symptoms and, mainly, regarding the initial approach and effective cardiac compressions, was present in most of the target audience. Urgent and emergency situations can result in serious clinical outcomes, sequels and even death of the victims. A trained layperson, capable of identifying and carrying out the necessary actions, can considerably improve the prognosis of victims who are in an urgent or emergency situation in society. It is important to provide quality and effective care, so that the victims do not have sequelae or, if they do, that these are minimal. Fast and efficient help is essential to avoid irreversible neurological damage, in addition to the risk of death that increases every minute. For this, it is necessary to start Cardiopulmonary Resuscitation (CPR) maneuvers as early as possible, even by a person who is not in the health area until specialized help arrives. In view of the results obtained, it is concluded that training on basic life support in cardiac arrest is still a little-known topic among the public addressed, which reflects a common scenario among the lay population and reinforces the importance of carrying out studies such as this in society, in order to disseminate basic knowledge that saves lives. It is essential that cardiopulmonary resuscitation training is not something exclusive to health professionals, the lay population needs to be guided so that they know how to act correctly in critical moments. The activities carried out spread health knowledge and provided subsidy so that the part of the contemplated population can also act as health educators.

Commotio Cordis: A Comprehensive Review.

Commotio cordis is a rare, however, potentially fatal, cardiovascular phenomenon arising from direct chest wall trauma, causing sudden cardiac arrest and potentially death. It is primarily seen in young athletes who participate in contact and organized sports. Though debated, the cause of commotio cordis is believed to involve specific timing of chest impact during ventricular electrical activity leading to severe arrhythmic events. Due to sudden onset, the first step in management is immediate and effective basic life support with automated external defibrillation, followed by advanced cardiac life support. Future considerations should include secondary prevention measures such as protective padding in contact sports. It is paramount that clinicians are vigilant in recognizing potential cases of commotio cordis in the field and provide immediate care. This review consolidates the current understanding of commotio cordis, emphasizing the importance of awareness and early intervention. Future research is warranted, including retrospective and observational studies to identify high-risk patterns or trends associated with the condition.

Cardiac involvement in patient-specific induced pluripotent stem cells of myotonic dystrophy type 1: unveiling the impact of voltage-gated sodium channels.

Myotonic dystrophy type 1 (DM1) is a genetic disorder that causes muscle weakness and myotonia. In DM1 patients, cardiac electrical manifestations include conduction defects and atrial fibrillation. DM1 results in the expansion of a CTG transcribed into CUG-containing transcripts that accumulate in the nucleus as RNA foci and alter the activity of several splicing regulators. The underlying pathological mechanism involves two key RNA-binding proteins (MBNL and CELF) with expanded CUG repeats that sequester MBNL and alter the activity of CELF resulting in spliceopathy and abnormal electrical activity. In the present study, we identified two DM1 patients with heart conduction abnormalities and characterized their hiPSC lines. Two differentiation protocols were used to investigate both the ventricular and the atrial electrophysiological aspects of DM1 and unveil the impact of the mutation on voltage-gated ion channels, electrical activity, and calcium homeostasis in DM1 cardiomyocytes derived from hiPSCs. Our analysis revealed the presence of molecular hallmarks of DM1, including the accumulation of RNA foci and sequestration of MBNL1 in DM1 hiPSC-CMs. We also observed mis-splicing of SCN5A and haploinsufficiency of DMPK. Furthermore, we conducted separate characterizations of atrial and ventricular electrical activity, conduction properties, and calcium homeostasis. Both DM1 cell lines exhibited reduced density of sodium and calcium currents, prolonged action potential duration, slower conduction velocity, and impaired calcium transient propagation in both ventricular and atrial cardiomyocytes. Notably, arrhythmogenic events were recorded, including both ventricular and atrial arrhythmias were observed in the two DM1 cell lines. These findings enhance our comprehension of the molecular mechanisms underlying DM1 and provide valuable insights into the pathophysiology of ventricular and atrial involvement.

Feasibility and safety of left bundle branch area pacing in patients with septal hypertrophy.

Left bundle branch area pacing (LBBAP) aims to provide physiological ventricular activation during pacing. Left ventricular septal hypertrophy (LVSH) might be challenging for LBBAP due to the thickness of the interventricular septum and potential presence of septal scar. This study assesses the feasibility, safety, and outcome of LBBAP in patients with LVSH using primarily stylet-driven leads (SDL). Adult patients with LVSH who underwent LBBAP between March 2019 and November 2022 were enrolled. Baseline patient characteristics, procedural data and postprocedural results were collected. The feasibility of LBBAP in LVSH patients was compared to a cohort of LBBAP patients with normal septal wall thickness (NST). SeventeenLVSH and 133 NST patients underwent LBBAP with successful implantation achieved in 15 LVSH patients (88%). Mean implant depth was 17.2 ± 1.9 mm, with 53% proven left bundle branch (LBB) capture. Paced QRS duration (146 ± 14 ms) and V6 R-wave peak time (V6 RWPT; 79 ± 20 ms) were comparable between patients with and without septal hypertrophy, although patients with NST had higher rates of proven LBB capture (71% vs. 53%). In LVSH pacing thresholds (0.6 ± 0.3 V at 0.4 ms) and R-wave amplitude (13.9 ± 5.6 mV) were favorable and remained stable at follow-up. At 12 months, 87% of patients had stable or improved left ventricular ejection fraction. The results of the study indicate that LBBAP in patients with LVSH is safe and feasible and no lead-related complications were observed despite a mean implant depth exceeding 15 mm. LBBAP using SDL results in favorable pacing and electrocardiographic characteristics in LVSH patients, comparable to patients with NST.

Mobile Cardiac Telemetry Use to Predict Adverse Pregnancy Outcomes in Patients With Congenital Heart Disease

BackgroundPatients with congenital heart disease (CHD) have a higher incidence of arrhythmias during pregnancy, yet the utility of mobile cardiac telemetry (MCT) to predict adverse outcomes is unknown. ObjectivesThe purpose of this study is to determine whether arrhythmias on screening MCT correlate with adverse pregnancy outcomes. MethodsPatients with CHD prospectively enrolled in the Standardized Outcomes in Reproductive Cardiovascular Care initiative underwent 24-hour MCT (within 18 months prior to pregnancy). Positive findings on MCT were defined as episodes of bradyarrhythmia, symptomatic atrioventricular block, ectopic atrial or ventricular activity, and supraventricular or ventricular tachycardia. Clinically significant arrhythmia events (CSAEs) were those requiring medical or device intervention or an emergency room visit. Clinical events during the antepartum, intrapartum, and postpartum periods were compared using Fisher’s exact test. Analyses were performed using Stata version 16. ResultsIn 141 pregnancies in 118 patients with CHD, MCT detected positive findings in 17%. Adverse cardiac outcomes occurred in 11% of pregnancies, of which CSAE occurred in 3.5%. Positive MCT was significantly associated with subsequent CSAE (21% vs 0%, P < 0.001) and cumulative adverse maternal cardiac outcomes (33% vs 7%, P = 0.001) but did not correlate with obstetric (46% vs 41%, P = 0.660) or neonatal outcomes (33% vs 31%, P = 0.810). Of the patients with CSAE, 75% had ≥moderate CHD complexity. ConclusionsPatients with CHD had a high rate of positive MCT findings. This was associated with CSAE and adverse maternal cardiac outcomes. Patients with ≥moderate CHD complexity may benefit from screening MCT to improve preconceptual counseling and planning.

Contractile asymmetry and survival in patients with left bundle branch abnormality treated with cardiac resynchronization therapy.

Currently, electrical rather than mechanical parameters of delayed left ventricular (LV) activation are used for patient selection for cardiac resynchronization therapy (CRT). However, despite adhering to current guideline-based criteria, about one-third of heart failure (HF) patients fail to derive benefit from CRT. This study sought to investigate the prognostic survival significance of a recently introduced index of contractile asymmetry (ICA) based on the deformation of entire opposing LV walls in the context of selecting patients with HF and left bundle branch abnormality (LBBB) for CRT. We analysed 367 patients with HF and LBBB undergoing CRT (31.6% females, 69 ± 9 years, ischaemic aetiology in 50.7%, LV ejection fraction 27 ± 6%). ICA was calculated using LV strain rate values from curved anatomical M-mode plots of apical 2D echocardiography images. The predictive value of ICA was assessed using Kaplan-Meier analysis and Cox proportional hazards models. During a median follow-up time of 5.54 years, death or cardiac transplantation occurred in 105 (28.6%) cases. Higher baseline ICA values in all apical views, particularly in the two-chamber view (ICA-2ch), were associated with increased event-free survival, and the unadjusted hazard ratio was 0.28 (95% confidence interval 0.18-0.46). Higher ICA-2ch (>0.319 s-1) consistently predicted survival across clinical subgroups and remained significant after covariate adjustment, while the event rate sharply increased in low ICA-2ch cases. Additionally, including ICA-2ch improved the predictive value of the multivariate risk model containing the typical LBBB pattern. Pre-implant ICA suggests a quantitative prognostic threshold for both long-term survival and adverse outcomes following CRT implantation.

Noninvasive Electrical Mapping Compared with the Paced QRS Complex for Optimizing CRT Programmed Settings and Predicting Multidimensional Response

The aim was to test the hypothesis that left ventricular (LV) and right ventricular (RV) activation from body surface electrical mapping (CardioInsight 252-electrode vest, Medtronic) identifies optimal cardiac resynchronization therapy (CRT) pacing strategies and outcomes in 30 patients. The LV80, RV80, and BIV80 were defined as the times to 80% LV, RV, or biventricular electrical activation. Smaller differences in the LV80 and RV80 (|LV80-RV80|) with synchronized LV pacing predicted better LV function post-CRT (p = 0.0004) than the LV-paced QRS duration (p = 0.32). Likewise, a lower RV80 was associated with a better pre-CRT RV ejection fraction by CMR (r = − 0.40, p = 0.04) and predicted post-CRT improvements in myocardial oxygen uptake (p = 0.01) better than the biventricular-paced QRS (p = 0.38), while a lower LV80 with BIV pacing predicted lower post-CRT B-type natriuretic peptide (BNP) (p = 0.02). RV pacing improved LV function with smaller |LV80-RV80| (p = 0.009). In conclusion, 3-D electrical mapping predicted favorable post-CRT outcomes and informed effective pacing strategies.Graphical

Tricyclic hydrocarbon fluorene attenuates ventricular ionic currents and pressure development in the navaga cod

The release of polycyclic aromatic hydrocarbons (PAHs) into the environment due to oil and diesel fuel spills is a serious threat to Arctic fish populations. PAHs produce multiple toxic effects in fish, but disturbance of electrical and contractile activity of the heart seems to be the most negative effect. Our study focused on the effects of fluorene, a tricyclic PAH resembling the well-investigated tricyclic phenanthrene, on major ionic currents and action potential (AP) waveform in isolated ventricular myocytes and on contractile activity in isolated whole hearts of polar navaga cod (Eleginus nawaga). Among the studied currents, the repolarizing rapid delayed rectifier K+ current IKr demonstrated the highest sensitivity to fluorene with IC50 of 0.54 μM. The depolarizing inward currents, INa and ICaL, were inhibited with 10 μM fluorene by 20.2 ± 2.8 % and 27.9 ± 8.4 %, respectively, thereby being much less sensitive to fluorene than IKr. Inward rectifier IK1 current was insensitive to fluorene (up to 10 μM). While 3 μM fluorene prolonged APs, 10 μM also slowed the AP upstroke. Resting membrane potential was not affected by any tested concentrations. In isolated heart experiments 10 μM fluorene caused modest depression of ventricular contractile activity. Thus, we have demonstrated that fluorene, a tricyclic PAH present in high quantities in crude oil, strongly impacts electrical activity with only slight effects on contractile activity in the heart of the polar fish, the navaga cod.

Electric Field of the Heart on the Thorax Surface in Highly Trained Athletes during Initial Ventricular Activity

The article is focused on the study of the electrical remodeling of the “sports heart” using multichannel ECG mapping to make a more detailed and informative analysis of the excitation of the myocardium remodeled by sport activity. The study of the heart electrical activity was carried out from 64 unipolar electrodes on the thorax surface synchronously with standard limb leads in highly trained cross-country skiers (n = 15) and young non-trained men (n = 19) at rest. The amplitude-temporal and spatiotemporal characteristics of the electric field of the heart were measured. By the typical distribution of areas of the negative and positive cardiac potentials the durations of depolarization and its individual phases were estimated. ECGII was used to determine the duration of the R-R, PQ (PR), QRS, QT, QTc intervals; in the unipolar lead V5 the R-wave peak time (RWPTV5) was measured. In athletes, the duration of PQII, QTII, QTcII, RWPTV5 intervals were statistically significantly longer than in non-trained men. Analysis of the electrical field of the heart showed a difference in the ratio of the phases of ventricular depolarization in athletes and non-trained individuals at rest. The onset of ventricular depolarization and the first inversion of cardiac potential in athletes were significantly earlier than in non-trained people, while the completion and total duration of the period of ventricular depolarization did not differ. In skiers, the duration of the first inversion was significantly longer than in non-trained individuals; a tendency to shortening of the second period of stable location of potentials on the thorax surface was also shown. The use of surface ECG mapping made it possible to reveal differences in the spatiotemporal organization of heart ventricular depolarization between cross-country skiers and non-trained men at rest. The results of the study may be useful in the analysis of the electrical remodeling of the heart in athletes training the physical quality of endurance.

Prognostic value of R wave peak time in COVID-19 pneumonia.

R wave peak time (RWPT) is also known as intrinsicoid deflection time or ventricular activation time. It shows the conduction time from the endocardium in the ventricle to the epicardium. It provides diagnostic and prognostic information for many cardiovascular diseases, such as RWPT prolongation, left ventricular hypertrophy, volume overload, conduction system abnormalities, and myocardial ischemia. Objectives The aim of this study is to investigate the relationship between COVID-19 mortality and RWPT in superficial ECG. This study retrospectively examined 640 patients diagnosed with COVID-19 and treated in an intensive care unit at a single center between January 2021 and June 2022. All patients included in the study had clinical and radiological characteristics and signs of COVID-19 pneumonia. 640 patients included in the study were divided into 2 groups: surviving and deceased. There were 510 patients in the surviving group and 130 patients in the deceased group. The deceased group was found to be significantly older. The number of patients with COPD was higher in the deceased group. Troponin, lactate dehydrogenase (LDH), C-reactive protein (CRP), D-dimer and T-peak to T-end interval(Tpe) and RWPT were found to be significantly increased in the deceased group. In binary logistic regression analysis; age, COPD, LDH, CRP, troponin, D-dimer, Tpe interval, RWPT were determined as independent risk factors for mortality. Prolonged RWPT is useful in risk stratification for COVID-19 pneumonia mortality.

Functional significance of myocardial activity at 18F-FAPI PET/CT in hypertrophic cardiomyopathy identified by cardiac magnetic resonance feature-tracking strain analysis.

This study aimed to evaluate the functional significance of 18F-labeled fibroblast activation protein inhibitor (18F-FAPI) activity in hypertrophic cardiomyopathy (HCM) by comparison with cardiac magnetic resonance feature-tracking (CMR-FT) strain analysis. A total of 49 HCM patients were included in this study. Two independent control groups of healthy participants with a matched age and sex to the HCM patients were also enrolled. Left ventricular (LV) 18F-FAPI activity was analyzed for extent (FAPI%) and intensity (maximum target-to-background ratio, TBRmax). The CMR tissue characterization parameters of the LV included late gadolinium enhancement, native T1 value, and extracellular volume fraction. LV strain analysis was performed in radial, circumferential, and longitudinal peak strains (PS). Intense LV myocardial 18F-FAPI uptake was observed in HCM patients, whereas no obvious uptake was detected in healthy participants (median TBRmax, 9.1 vs. 1.2, p < 0.001). The strain parameters of HCM patients, compared with healthy participants, were significantly impaired (mean radial PS, 23.5 vs. 36.0, mean circumferential PS, -14.5 vs. -20.0, and mean longitudinal PS, -9.9 vs. -16.0, all p < 0.001). At segmental levels, there was a moderate correlation between 18F-FAPI activity and strain parameters. The number of positive 18F-FAPI uptake segments (n = 653) was higher than that of hypertrophic segments (n = 190) and positive CMR tissue characterization segments (n = 525) (all p < 0.001). In segments with negative CMR tissue characterization findings, the strain capacity of positive 18F-FAPI uptake segments was lower than that of negative 18F-FAPI uptake segments (median radial PS, 30.5 vs. 36.1, p = 0.026 and median circumferential PS, -18.4 vs. -19.7, p = 0.041). 18F-FAPI imaging can partially reflect the potential strain reduction in HCM patients. 18F-FAPI imaging detects more involved myocardium than CMR tissue characterization techniques, and the additionally identified myocardium has impaired strain capacity.

Left ventricular endocardial activation maps during right ventricular pacing in pediatric patients.

Cardiac pacing from right ventricular (RV) sites may cause electromechanical ventricular dyssynchrony. Invasive and noninvasive mapping studies showed left ventricular (LV) activation sequence in adults. Aim of this study was to seek out the LV endocardial activation (LVEA) in pediatric patients who underwent RV pacing. Single-center, prospective study conducted on pediatric patients who underwent left sided catheter ablation of accessory pathways with the Carto Univu mapping system. After successful ablation procedures, LVEA was recorded by the ablation catheter during sinus rhythm (SR) and during para-hisian (PHP), midseptum (MSP), and apical (RVAP) pacing. Seventeen patients, 13 males, aged 12 (10-15) years, registered LV activation maps and times (LVAT). SR showed significantly shorter LVAT than during pacing. LVAT of PHP was shorter than MSP, while there were not significant differences among PHP and MSP versus RVAP. In SR initial LV endocardial activation occurred in two midseptum sites, inferior-posterior and superior-anterior. During PHP, initial activation occurred at parahisian basal septum, rapidly followed by midseptum as in SR. During MSP and RVAP initial activation occurred at midseptum and apex, respectively. From all initial sites, the excitation spreads toward the base of the lateral LV free wall. A mild linear correlation was found between QRS duration and LVAT for MSP and for PHP. In pediatric patients LVEA maps during RV pacing showed that the shortest LVAT was obtained with PHP. The LV activation pattern seemed similar in sinus rhythm, PHP and MSP, from midseptum to LV lateral base.