BACKGROUND:Implantable cardioverter-defibrillators (ICDs) are essential for preventing sudden cardiac death in patients with ischemic cardiomyopathy (ICM). Noninvasive programmed stimulation (NIPS) is a potential tool for predicting ventricle tachycardia (VT) or ventricle fibrillation (VF) and helps to select patients with higher arrhythmic risk. This study aimed to evaluate the predictive value of NIPS in identifying ICM patients at risk for VT/VF episodes and mortality after ICD implantation for primary prevention. METHODS:This prospective, single-center study included 50 patients with ICM who underwent ICD or CRT-D implantation for primary prevention. NIPS was performed between 1- and 3-months following implantation and patients were followed for VT/VF recurrence and mortality. RESULTS:Positive NIPS was observed in 20% of patients. During a median follow-up of 5.67 years, VT/VF occurred in 16% of patients. Kaplan-Meier analysis demonstrated a significantly increased risk of VT/VF episodes in the positive NIPS group (log-rank test, p = 0.047), with a considerably shorter time to VT/VF incidence (0.58 vs. 4.75 years). NIPS was not positively associated with an increased mortality rate (p = 0.45). However, elevated levels of creatinine and NT-pro BNP were significantly associated with higher mortality. CONCLUSIONS:NIPS positivity predicts an increased risk of VT/VF episodes, supporting its role in predicting arrhythmic episodes but not mortality after ICD implantation for primary prevention with ICM. Creatinine and NT-proBNP levels were significantly associated with patient survival. TRIAL REGISTRATION:This prospective study was not registered in a public clinical trials registry, as registration was not required at the time of study initiation.

In recent years, Bachmann's bundle (BB), a band of cardiac muscle that enables electrical conduction from the heart's right atrium to the left atrium, has drawn significant interest from the scientific community. It has been identified as a branch of the anterior interatrial pathways connecting the sinoatrial node to the atrioventricular node, departing at the level of the superior vena cava. It is now understood that BB serves as a preferential pathway for interatrial conduction, and structural abnormalities in BB can result in interatrial block, which is associated with the onset of atrial fibrillation and flutter. Studies have also demonstrated that within BB, the incidence of conduction abnormalities (such as conduction delay and conduction block) increases with age. In addition, recently published studies have shown that in obese patients, areas of low voltage are mainly located over the anterior wall, where BB is mostly present, suggesting that the deposition of epicardial fat may predominantly affect the function of this important structure in the heart. Therefore, BB is undoubtedly a structure that merits further investigation, as its role remains unclear, particularly regarding its impact on the development of new treatments. The goal of this review is to describe structural and functional changes in BB in obese, elderly patients as well as those with cardiovascular abnormalities.

BACKGROUND:Eustachian valve endocarditis (EVE) is a rare right-sided infective endocarditis (RSIE) manifestation. This condition has scattered and limited clinical characteristics that require collection and systematization. This meta-analysis evaluates the predisposing factors, pathogens, and associated risk profiles in EVE cases. METHODS:The meta-analysis included 68 cases of EVE from 57 reports published between 1986 and 2024 from PubMed, Embase, Scopus, Cochrane, and Web of Science. Data on demographics, clinical characteristics, risk factors, and microbiological findings were extracted and analyzed using descriptive and univariate statistical methods. Pooled prevalence rates from observational studies were calculated using a fixed effects model. RESULTS:The pooled prevalence of EVE in RSIE among the analyzed cases was 2.54%. Single-valve infections accounted for 70.6% of cases, with the Eustachian valve as the sole affected structure. The most common pathogen was Staphylococcus aureus (60%), predominantly affecting younger intravenous drug users (IVDU) with an odds ratio [OR (odds ratio) = 6.27; 95% CI (confidence interval): 1.62-24.31] in univariate logistic regression analysis. Other predisposing factors, including central venous catheters (CVCs) and cardiac implantable electronic devices (CIED), were not significantly associated with Staphylococcus aureus or other bacterial non-Staphylococcus aureus or fungal infections. CONCLUSIONS:Eustachian valve endocarditis is relatively rare and primarily associated with IVDU and younger age, whereas CVCs and CIEDs are insignificant predictors. Identifying embryonic remnants like the Eustachian valve or Chiari network using echocardiography may facilitate early diagnosis in at-risk populations.

The pulmonary root has emerged as a critical target for catheter ablation of ventricular arrhythmias, accounting for approximately 11

IntroductionHigh-resolution digitized cardiac anatomical data sets are in huge demand in clinical, basic research and computational settings. They can be leveraged to evaluate intricate anatomical and structural changes in disease pathology, such as myocardial infarction (MI), which is one of the most common causes of heart failure and death. Advancements in high-resolution imaging and anatomical techniques in this field and our laboratory have led to vast improvements in understanding cardiovascular anatomy, especially the cardiac conduction system (CCS) responsible for the electricity of the heart, in healthy/aged/obese post-mortem human hearts. However, the digitized anatomy of the electrical system of the heart within MI hearts remains unexplored.MethodsFive post-mortem non-MI and MI human hearts were obtained by the Visible Heart® Laboratories via LifeSource, Minneapolis, MN, United States (with appropriate ethics and consent): specimens were then transported to Manchester University with an material transfer agreement in place and stored under the HTA 2004, UK. After performing contrast-enhanced micro-CT, a visualization tool (namely Amira) was used for 3D high-resolution anatomical visualizations and reconstruction. Various cardiovascular structures were segmented based on the attenuation difference of micro-CT scans and tissue traceability. The relationship between the CCS and surrounding tissues in MI and non-MI human hearts was obtained. 3D anatomical models were further explored for their use in computational simulations, 3D printing and mix/virtual reality visualization.Results3D segmented cardiovascular structures in the MI hearts elicited diverse macro-/micro- anatomical changes. The key findings are thickened valve leaflets, formation of new coronary arteries, increased or reduced thicknesses of pectinate and papillary muscles and Purkinje fibers, thinner left bundle branches, sinoatrial nodal atrophy, atrioventricular conduction axis fragmentation, and increased epicardial fat in some hearts. The propagation of the excitation impulses can be simulated, and 3D printing can be utilized from the reconstructed and segmented structures.DiscussionHigh-resolution digitized cardiac anatomical datasets offer exciting new tools for medical education, clinical applications, and computational simulation.

The most commonly applied way of teaching students to convey the foundations of human anatomy and physiology involves textbooks and lectures. This way of transmitting knowledge causes difficulties for students, especially in the context of three-dimensional imaging of organ structures, and as a consequence translates into difficulties with imagining them. Even despite the rapid uptake of knowledge dissemination provided by online materials, including courses and webinars, there is a clear need for learning programs featuring first-hand immersive experiences tailored to suit individual study paces. In this paper, we present an approach to enhance a classical study program by combining multi-modality data and representing them in a Mixed Reality (MR)-based environment. The advantages of the proposed approach have been proven by the conducted investigation of the relationship between atrial anatomy, its electrophysiological characteristics, and resulting P wave morphology on the electrocardiogram (ECG). Another part of the paper focuses on the role of the sinoatrial node in ECG formation, while the MR-based visualization of combined micro-computed tomography (micro-CT) data with non-invasive CineECG imaging demonstrates the educational application of these advanced technologies for teaching cardiac anatomy and ECG correlations.

BACKGROUND: Although radiofrequency ablation of the cavotricuspid isthmus (CTI), responsible for sustaining atrial flutter, is a highly effective procedure, in extended patient observations following this procedure, more than 10% becomeunsuccessful. Therefore, this study was aimed at providing helpful information about the anatomy of the CTI in transthoracic echocardiography, which could aid better planning of CTI radiofrequency ablation in patients with typical atrial flutter. MATERIALS AND METHODS: 56 patients with typical atrial flutter after radiofrequency ablation were evaluated at the end of a 24-month observation period. With substernal modified transthoracic echocardiographic (mTTE) evaluation, we identified four main anatomical obstacles impeding radiofrequency ablation: tricuspid annular plane systolic excursion, cavotricuspid isthmus length, cavotricuspid isthmus morphology, and the presence of a prominent Eustachian ridge/Eustachian valve. All intraprocedural radiofrequency ablation data was collected for analysis and correlated with anatomical data. RESULTS: Over a 24-month observation period, freedom from atrial flutter was 67.86%. The mean length of the isthmus was 30.34 ± 6.67 mm. The isthmus morphology in the 56 patients was categorised as flat (n = 27; 48.2%), concave (n = 10; 17.85%), or pouch (n = 19, 33.9%). A prominent Eustachian ridge was observed in 23 patients (41.1%). Lack of anatomical obstacles in mTTE evaluation resulted in 100% efficacy, while the presence of at least two obstacles significantly increased the risk of unsuccessful ablation with more than two (OR 12.31 p = 0.01). Generally, 8 mm electrodes were the most effective for non-difficult CTI, while 3.5 mm electrodes used with a 3D system had highest performance forcomplex CTI. Notably, ageing was the only factor that worsened the long-term outcome (OR 1.07 p = 0.044). CONCLUSIONS: Preoperative use of mTTE evaluation helps predict difficulty in cavotricuspid isthmus radiofrequency ablation, thus allowing better planning of the radiofrequency ablation strategy using the most accurate radiofrequency ablation electrode.

(1) Background: The sinus node (SN) is the main pacemaker of the heart. It is characterized by pacemaker cells that lack mitochondria and contractile elements. We investigated the possibility that transcription factors (TFs) and microRNAs (miRs) present in the SN can regulate gene expression that affects SN morphology and function. (2) Methods: From human next-generation sequencing data, a list of mRNAs that are expressed at lower levels in the SN compared with the right atrium (RA) was compiled. The mRNAs were then classified into contractile, mitochondrial or glycogen mRNAs using bioinformatic software, RStudio and Ingenuity Pathway Analysis. The mRNAs were combined with TFs and miRs to predict their interactions. (3) Results: From a compilation of the 1357 mRNAs, 280 contractile mRNAs and 198 mitochondrial mRNAs were identified to be expressed at lower levels in the SN compared with RA. TFs and miRs were shown to interact with contractile and mitochondrial function-related mRNAs. (4) Conclusions: In human SN, TFs (MYCN, SOX2, NUPR1 and PRDM16) mainly regulate mitochondrial mRNAs (COX5A, SLC25A11 and NDUFA8), while miRs (miR-153-3p, miR-654-5p, miR-10a-5p and miR-215-5p) mainly regulate contractile mRNAs (RYR2, CAMK2A and PRKAR1A). TF and miR-mRNA interactions provide a further understanding of the complex molecular makeup of the SN and potential therapeutic targets for cardiovascular treatments.

Research purpose The sinoatrial node (SN) is the main pacemaker site, and it is located in the junctional area of the superior vena cava within the right atrium (RA). The precise micro-anatomy of the SN in males and females in ageing and obesity remains unclear. Basic procedures Human SN/RA specimens were dissected from 25 post-mortem hearts (preserved in 4% formaldehyde solution), under Polish local ethical rules. The SN/RA tissue blocks were embedded in paraffin. Masson’s Trichrome staining and immunohistochemistry for CD31 (a marker of endothelial cells) and CD68 (a marker of macrophages) were performed. Images at different magnifications were taken and analysed. 12-lead ECGs from 24 patients under Polish local ethical rules were obtained. Heart rate and P wave morphologies from lead II, lead III and lead aVF were analysed. Statistical analysis was performed with the unpaired t-test. Principal results Heart weight to body weight ratio was significantly higher in aged obese males vs. their female counterparts. In the RA samples, there was an increase in connective tissue and decreased myocyte content from aged obese females compared to aged obese males. Aged non-obese males had significantly increased cellular hypertrophy than the aged non-obese females. Both the aged obese and aged non-obese females showed more CD3 but less CD68 expressing cells than males. In the SN samples, CD31 and CD68 expressing cells were higher in both aged non-obese and aged obese males than their female counterparts. Major conclusions Ageing and/or obesity are more likely to impact these cardiac tissues through increased inflammation, increased immune response and hypertrophy.

BACKGROUND:Cryoballoon ablation for treatment of atrial fibrillation (AF) reduces procedure times, but limited data is available about its impact on electrophysiology (EP) lab efficiency in Central and Eastern Europe (CEE). Using CEE-specific procedure data, the present study modeled cryoballoon ablation procedures on EP lab resource consumption to improve efficiency. METHODS:A discrete event simulation model was developed to assess EP efficiency with cryoballoon ablation. Model inputs were taken from CEE sites within the Cryo Global Registry, namely Czech Republic, Hungary, Poland, Serbia, and Slovakia. The main endpoints were percentage of days that resulted in overtime and percentage of days with time for one extra simple EP procedure. Use of the 'figure of 8' (Fo8) closure technique to reduce procedure time was also examined. RESULTS:The mean lab occupancy time across all CEE sites was 133 ± 47 minutes (min: 104 minutes, max:181 minutes). Cryoballoon ablation in the base-case scenario resulted in 14.6% of days with overtime and 64.8% of days with time for an extra simple EP procedure. Use of the Fo8 closure technique enhanced these values to 5.5% and 85.3%, respectively. Model endpoints were most sensitive to changes in lab occupancy times and overtime start time. CONCLUSIONS:In this CEE-specific analysis of EP lab efficiency it was found that 3 cryoballoon ablation procedures could be performed in 1 lab day, leaving time for a 4th simple EP procedure on most days. As such, use cryoballoon ablation for PVI is an effective way to improve EP lab efficiency.

IntroductionThe sinus node (SN) is the main pacemaker site of the heart, located in the upper right atrium at the junction of the superior vena cava and right atrium. The precise morphology of the SN in the human heart remains relatively unclear especially the SN microscopical anatomy in the hearts of aged and obese individuals. In this study, the histology of the SN with surrounding right atrial (RA) muscle was analyzed from young non-obese, aged non-obese, aged obese and young obese individuals. The impacts of aging and obesity on fibrosis, apoptosis and cellular hypertrophy were investigated in the SN and RA. Moreover, the impact of obesity on P wave morphology in ECG was also analyzed to determine the speed and conduction of the impulse generated by the SN.MethodsHuman SN/RA specimens were dissected from 23 post-mortem hearts (preserved in 4% formaldehyde solution), under Polish local ethical rules. The SN/RA tissue blocks were embedded in paraffin and histologically stained with Masson’s Trichrome. High and low-magnification images were taken, and analysis was done for appropriate statistical tests on Prism (GraphPad, USA). 12-lead ECGs from 14 patients under Polish local ethical rules were obtained. The P wave morphologies from lead II, lead III and lead aVF were analyzed.ResultsCompared to the surrounding RA, the SN in all four groups has significantly more connective tissue (P ≤ 0.05) (young non-obese individuals, aged non-obese individuals, aged obese individuals and young obese individuals) and significantly smaller nodal cells (P ≤ 0.05) (young non-obese individuals, aged non-obese individuals, aged obese individuals, young obese individuals). In aging, overall, there was a significant increase in fibrosis, apoptosis, and cellular hypertrophy in the SN (P ≤ 0.05) and RA (P ≤ 0.05). Obesity did not further exacerbate fibrosis but caused a further increase in cellular hypertrophy (SN P ≤ 0.05, RA P ≤ 0.05), especially in young obese individuals. However, there was more infiltrating fat within the SN and RA bundles in obesity. Compared to the young non-obese individuals, the young obese individuals showed decreased P wave amplitude and P wave slope in aVF lead.DiscussionAging and obesity are two risk factors for extensive fibrosis and cellular hypertrophy in SN and RA. Obesity exacerbates the morphological alterations, especially hypertrophy of nodal and atrial myocytes. These morphological alterations might lead to functional alterations and eventually cause cardiovascular diseases, such as SN dysfunction, atrial fibrillation, bradycardia, and heart failure.

Background: Evidence indicates that radiofrequency catheter ablation (RFCA) of ventricular tachy-cardia (VT) in patients with structural heart disease (SHD) is safe and effective. However, arrhythmia recurrence is still relatively high, and the optimal procedural strategy is unclear. In clinical practice, several combinations of mapping and ablation techniques are used to improve VT ablation efficacy. Aim:The study aimed to evaluate and provide evidence on the efficiency and safety of a systematized combination of VT ablation (mapping) techniques in patients with SHD. Methods: From 2016 to 2019, 47 patients (54 procedures) with SHD (89% heart failure, 94% isch-emic heart disease, 37% VT storm) who underwent RFCA of VT were retrospectively analyzed from a group of 58 consecutive patients. During RFCA of VT, different combinations of three techniques, activation mapping (AM), pace mapping (PM), and substrate-based mapping (SbM), were used. The procedures were performed using the CARTO (R) 3 (Biosense Webster Inc., Diamond Bar, CA, US) electro-anatomical mapping system. Results: During a median (interquartile range [IQR]) follow-up of 25.5 months (11.75-52.25), VT-free survival after ablation was 68.5% (n = 37/54 procedures). Acute procedural success was achieved in 85% (n = 46/54 procedures). The number of induced VT morphologies, induction of non-clinical or non-sustained VT after ablation, and fewer VT mapping techniques used during the procedure were related to decreasing VT-free survival. Conclusions: VT ablation strategy based on systemic use of combined techniques is effective and safe in long-term follow-up of patients with SHD.

Background: ST segment deviation is common in patients with narrow QRS complex tachycardia. It mainly concerns young people in whom ischemic background is unlikely. In our work we would also like to propose another potential mechanism - the overlapping of individual components of the QRS complex. Material and methods: The study included 11 patients (7 women and 4 men) with paroxysmal narrow QRS complex tachycardia. An electrophysiological study was performed in all patients, the diagnosis of atrioventricular reentrant tachycardia was established and finally successful RF ablation was done. We measured the individual components of QRS QR, RS and RJ during sinus rhythm and during tachycardia. Results: The difference RJ-QR during tachycardia correlated negatively with tachycardia cycle length T(r = -0.85, p = 0.000831 ). We also showed a significant difference between the amplitude of the RJ segment in tachycardia and during sinus rhythm (p = 0.005), at the same time we showed no differences between the amplitude of QR and RS. Conclusions: We showed a statistically significant difference in ST segment depression in correlation with the rate of tachycardia in patients with AVRT resulting mainly from the overlapping of individual components of the QRS complex.

Introduction Single atrial stimulation (AAI) has been commonly used for permanent pacing in sick sinus syndrome and significant bradycardia. Objectives The study aimed to evaluate long-term AAI pacing and to identify timing and reasons for pacing mode change. Patient s and methods Retrospectively, we included 207 patients (60% women) with initial AAI pacing, who were followed-up for an average of 12 years. Results At the time of death or loss to follow-up, 71 patients (34.3%) had unchanged AAI pacing mode. The reason for an upgrade of the pacing system was development of atrial fibrillation (AF) in 43 patients ( 20.78%) and atrioventricular block (AVB) in 34 patients ( 16.4%). The cumulative ratio for a pacemaker upgrade reoperation reached 2.77 per 100 patient-years of the follow-up. Cumulative ventricular pacing below 10% after an upgrade to dual-chamber pacemaker was observed in 28.6% of the patients. Younger age at implant was the leading independent predictor of the change to dual-chamber simulation ( hazard ratio, 1.98; 95% CI, 1.976-1.988; P = 0.001). There were 11 (5%) lead malfunctions that required reoperation. Subclavian vein occlusion was noted in 9 upgrade procedures (11%). One cardiac device- related infection was observed. Conclusions The reliability of AAI pacing decreases with each year of observation due to development of AF and AVB. However, in the current era of effective AF treatment, the advantages of AAI pacemakers, such as lower incidence of lead malfunction, venous occlusion, and infection, as compared with dual- chamber pacemakers, may make AAI pacemakers a viable option.

The objective of the present meta-analysis was to evaluate recent and applicable data regarding the location and variation of the atrioventricular nodal artery (AVNA) in relation to adjacent structures. In order to minimize postoperative risks and maintain physiological anastomosis for proper cardiac function, understanding such possible variations of vascularization of the AV node is of immense importance prior to cardiothoracic surgery as well as ablations. In order to perform this meta-analysis, a systematic search was conducted in which all articles regarding, or at least mentioning, the anatomy of the AVNA was searched. In general, the results were based on 3919 patients. AVNA was found to originate only from the RCA in 82.41% (95% CI: 79.46%-85.18%). The pooled prevalence of AVNA originating only from LCA was found to be 15.25% (95% CI: 12.71%-17.97%). The mean length of AVNA was found to be 22.64 mm (SE = 1.60). The mean maximal diameter of AVNA at its origin was found to be 1.40 mm (SE = 0.14). In conclusion, we believe that this is the most accurate and up-to-date study regarding the highly variable anatomy of the AVNA. The AVNA was found to originate most commonly from the RCA (82.41%). Furthermore, the AVNA was found to most commonly have no (52.46%) or only one branch (33.74%). It is hoped that the results of the present meta-analysis will be helpful for physicians performing cardiothoracic or ablation procedures.

•Graphene oxide is a novel contrast agent for micro-computed tomography to visualise fat within and around the heart.•I2KI is a contrast agent for micro-computed tomography to visualise cardiovascular structures.•3D reconstruction showed complex changes to cardiac chambers and coronary arteries in the aged and obese hearts vs. normal.•The obese heart had profound amounts of epicardial fat.•In the obese and aged hearts, the nodal tissues were either replaced by fat or were fibrotic respectively.