Morphology of human sinoatrial node and its surrounding right atrial muscle in the global obesity pandemic-does fat matter?

Introduction: The 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. Methods: Human 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. Results: Compared 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. Discussion: Aging 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.

Permanent single-chamber atrial pacing: an obsolete or viable alternative to dual-chamber pacing in selected patients with sinus node disease?

INTRODUCTION: Single atrial stimulation (AAI) has been commonly used for permanent pacing in sick sinus syndrome and significant bradycardia. OBJECTIVE: The study aimed to evaluate long­term AAI pacing and to identify timing and reasons for pacing mode change. PATIENTS AND METHODS: Retrospectively, we included 207 patients (60% women) with initial AAI pacing, who were followed­up for an average of 12 years. RESULTS: At the time of death or loss to follow­up, 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 patient­years of the follow­up. Cumulative ventricular pacing below 10% after an upgrade to dual­chamber pacemaker was observed in 28.6% of the patients. Younger age at implant was the leading independent predictor of the change to dual­chamber 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 anatomy of the atrioventricular nodal artery: A meta-analysis with implications for cardiothoracic surgery and ablation procedures.

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.

Radiofrequency catheter ablation of ventricular tachycardia using combined endocardial techniques in patients with structural heart disease improves procedural effectiveness and reduces arrhythmia episodes.

BACKGROUND: Evidence indicates that radiofrequency catheter ablation (RFCA) of ventricular tachycardia (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% ischemic 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® 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.

Prevalence of Arrhythmia in Adults after Fontan Operation.

Structural, hemodynamic, and morphological cardiac changes following Fontan operation (FO) can contribute to the development of arrhythmias and conduction disorders. Sinus node dysfunction, junction rhythms, tachyarrhythmias, and ventricular arrhythmias (VAs) are some of the commonly reported arrhythmias. Only a few studies have analyzed this condition in adults after FO. This study aimed to determine the type and prevalence of arrhythmias and conduction disorders among patients who underwent FO and were under the medical surveillance of the John Paul II Hospital in Krakow. Data for the study were obtained from 50 FO patients (mean age 24 ± 5.7 years; 28 men (56%)). The median follow-up time was 4 (2-9) years. Each patient received a physical examination, an echocardiographic assessment, and a 24 h electrocardiogram assessment. Bradyarrhythmia was diagnosed in 22 patients (44%), supraventricular tachyarrhythmias in 14 patients (28%), and VAs in 6 patients (12%). Six patients required pacemaker implantation, and three required radiofrequency catheter ablation (6%). Arrythmias is a widespread clinical problem in adults after FO. It can lead to serious haemodynamic impairment, and therefore requires early diagnosis and effective treatment with the use of modern approaches, including electrotherapy methods.

Contact Force-Sensing versus Standard Catheters in Non-Fluoroscopic Radiofrequency Catheter Ablation of Idiopathic Outflow Tract Ventricular Arrhythmias.

BACKGROUND: Adequate contact between the catheter tip and tissue is important for optimal lesion formation and, in some procedures, it has been associated with improved effectiveness and safety. We evaluated the potential benefits of contact force-sensing (CFS) catheters during non-fluoroscopic radiofrequency catheter ablation (NF-RFCA) of idiopathic ventricular arrhythmias (VAs) originating from outflow tracts (OTs). METHODS: A group of 102 patients who underwent NF-RFCA (CARTO, Biosense Webster Inc., Irvine, CA, USA) of VAs from OTs between 2014 to 2018 was retrospectively analyzed. RESULTS: We included 52 (50.9%) patients in whom NF-RFCA was performed using CFS catheters and 50 (49.1%) who were ablated using standard catheters. Arrhythmias were localized in the right and left OT in 70 (68.6%) and 32 (31.4%) patients, respectively. The RFCA acute success rate was 96.1% (n = 98) and long-term success during a minimum 12-month follow-up (mean 51.3 ± 21.6 months) was 85.3% (n = 87), with no difference between CFS and standard catheters. There was no difference in complications rate between CFS (n = 1) and standard catheter (n = 2) ablations. CONCLUSIONS: There is no additional advantage of CFS catheters use over standard catheters during NF-RFCA of OT-VAs in terms of procedural effectiveness and safety.

Compound motor action potentials in transient and persistent phrenic nerve injury - metanalysis.

BACKGROUND: The right phrenic nerve is vulnerable to injury (PNI) during cryoballoon ablation (CBA) isolation of the right pulmonary veins. The complication can be transient or persistent. The reported incidence of PNI fluctuates from 4.73% to 24.7% depending on changes over time, CBA generation, and selected protective methods. M e t h o d s: Through September 2019, a database search was performed on MEDLINE, EMBASE, and Cochrane Database. In the selected articles, the references were also extensively searched. The study provides a comprehensive meta-analysis of the overall prevalence of PNI, assesses the transient to persistent PNI ratio, the outcome of using compound motor action potentials (CMAP), and estimated average time to nerve recovery. R e s u l t s: From 2008 to 2019, 10,341 records from 48 trials were included. Out of 783 PNI retrieved from the studies, 589 (5.7%) and 194 (1.9%) were persistent. CMAP caused a significant reduction in the risk of persistent PNI from 2.3% to 1.1% (p = 0.05; odds ratio [OR] 2.13) in all CBA groups. The mean time to PNI recovery extended beyond the hospital discharge was significantly shorter in CMAP group at three months on average versus non CMAP at six months (p = 0.012). CMAP (in contrast to non-CMAP procedures) detects PNI earlier from 4 to 16 sec (p <0.05; I2 = 74.53%) and 3 to 9o (p <0.05; I2 = 97.24%) earlier. C o n c l u s i o n s: Right PNI extending beyond hospitalization is a relatively rare complication. CMAP use causes a significant decrease in the risk of prolonged injury and shortens the time to recovery.

Left Ventricular Summit-Concept, Anatomical Structure and Clinical Significance.

The left ventricular summit (LVS) is a triangular area located at the most superior portion of the left epicardial ventricular region, surrounded by the two branches of the left coronary artery: the left anterior interventricular artery and the left circumflex artery. The triangle is bounded by the apex, septal and mitral margins and base. This review aims to provide a systematic and comprehensive anatomical description and proper terminology in the LVS region that may facilitate exchanging information among anatomists and electrophysiologists, increasing knowledge of this cardiac region. We postulate that the most dominant septal perforator (not the first septal perforator) should characterize the LVS definition. Abundant epicardial adipose tissue overlying the LVS myocardium may affect arrhythmogenic processes and electrophysiological procedures within the LVS region. The LVS is divided into two clinically significant regions: accessible and inaccessible areas. Rich arterial and venous coronary vasculature and a relatively dense network of cardiac autonomic nerve fibers are present within the LVS boundaries. Although the approach to the LVS may be challenging, it can be executed indirectly using the surrounding structures. Delivery of the proper radiofrequency energy to the arrhythmia source, avoiding coronary artery damage at the same time, may be a challenge. Therefore, coronary angiography or cardiac computed tomography imaging is strongly recommended before any procedure within the LVS region. Further research on LVS morphology and physiology should increase the safety and effectiveness of invasive electrophysiological procedures performed within this region of the human heart.

Further insights into the molecular complexity of the human sinus node - The role of 'novel' transcription factors and microRNAs.

RESEARCH PURPOSE: The sinus node (SN) is the heart's primary pacemaker. Key ion channels (mainly the funny channel, HCN4) and Ca2+-handling proteins in the SN are responsible for its function. Transcription factors (TFs) regulate gene expression through inhibition or activation and microRNAs (miRs) do this through inhibition. There is high expression of macrophages and mast cells within the SN connective tissue. 'Novel'/unexplored TFs and miRs in the regulation of ion channels and immune cells in the SN are not well understood. Using RNAseq and bioinformatics, the expression profile and predicted interaction of key TFs and cell markers with key miRs in the adult human SN vs. right atrial tissue (RA) were determined. PRINCIPAL RESULTS: 68 and 60 TFs significantly more or less expressed in the SN vs. RA respectively. Among those more expressed were ISL1 and TBX3 (involved in embryonic development of the SN) and 'novel' RUNX1-2, CEBPA, GLI1-2 and SOX2. These TFs were predicted to regulate HCN4 expression in the SN. Markers for different cells: fibroblasts (COL1A1), fat (FABP4), macrophages (CSF1R and CD209), natural killer (GZMA) and mast (TPSAB1) were significantly more expressed in the SN vs. RA. Interestingly, RUNX1-3, CEBPA and GLI1 also regulate expression of these cells. MiR-486-3p inhibits HCN4 and markers involved in immune response. MAJOR CONCLUSIONS: In conclusion, RUNX1-2, CSF1R, TPSAB1, COL1A1 and HCN4 are highly expressed in the SN but not miR-486-3p. Their complex interactions can be used to treat SN dysfunction such as bradycardia. Interestingly, another research group recently reported miR-486-3p is upregulated in blood samples from severe COVID-19 patients who suffer from bradycardia.

Applicability of computed tomography preoperative assessment of the LAA in LV summit ablations.

PURPOSE: Ventricular arrhythmias originating from the left ventricular summit (LVS) may present with challenges for catheter ablation. Recently, the left atrial appendage (LAA) became a new vantage point for mapping and ablating arrhythmias from that region, but data of possible usefulness is limited. METHODS: From September to December 2019, we retrospectively analyzed 48 consecutive patient hearts (20 male; mean age 57.9y ± 11.56) undergoing diagnostic coronary vessel imaging in 64 dual-source computer tomography angiography (CTA). Distances from the LAA to the LVS, LAA shape type, and coronary arteries in the LVS region were measured. Also, we compared the true LVS area from CTA with a calculated formula derived from LVS definition. RESULTS: The mean LVS area calculated from the formula was 291.58 mm2 (± 115.5) while the true area calculated from CT was 263.33 mm2 (± 99.49) (p = 0.44). The mean inaccessible area was 133.42 mm2 (± 72.89), accessible 95.67 mm2 (± 72.77). The mean LAA coverage over LVS was 196.08 mm2-which is approximately 75% of LVS size in general. The most common LAA shape was chicken wing (50%); windsock has the highest accessible area coverage on average (80.23%), followed by chicken wing (59.88%), broccoli (47.72%), and cactus (46.98%). The mean distance from LAA to the surface was 5.14 mm (1.5 to 10 mm) and was not correlated with BMI. LAA has a 98% coverage over the point of transition between the great cardiac vein and anterior interventricular vein. CONCLUSION: Angio-CT assessment of the LAA over the LVS structures may be helpful in decision making before an ablation procedure. LAA appears to be a promising mapping approach in LVS arrhythmias.

[Atrial flutter in cardiology practice]. / Trzepotanie przedsionków w praktyce kardiologa.

Atrial flutter (AFL) is one of the most common arrhythmias present in clinical practice, both for the GPs and cardiologist practice. After atrial fibrillation (AF) is second the most common supraventricular arrhythmia. This usually occurs along the cavo-tricuspid isthmus of the right atrium though atrial flutter can originate from the left atrium as well. As AFL is rarely susceptible to pharmacotherapy, that is why, the guidelines of the European and American Cardiology Societies suggest non-pharmacological treatment - an ablation, which is a "gold standard". Due to the reentrant nature of atrial flutter, it is often possible to ablate the circuit that causes atrial flutter with radiofrequency catheter ablation. Catheter ablation is considered to be a first-line treatment method for many people with typical atrial flutter due to its high rate of success (>90%) and low incidence of complications. This is done in the cardiac electrophysiology lab by causing a ridge of scar tissue in the cavo-tricuspid isthmus that crosses the path of the circuit that causes atrial flutter. Eliminating conduction through the isthmus prevents reentry, and if successful, prevents the recurrence of the atrial flutter. Atrial fibrillation often occurs after catheter ablation for atrial flutter. We present an up to date overview of the most important information about AFL based on the available literature.

Non-fluoroscopic radiofrequency catheter ablation of right- and left-sided ventricular arrhythmias.

INTRODUCTION: Radiofrequency catheter ablation (RFCA) is an important method of treatment of ventricular arrhythmias (VAs). In the majority of RFCA, fluoroscopy is used, exposing patients and medical staff to all related side effects. Current experience of non-fluoroscopic (NF)-RFCA in VAs from the left side is limited. AIM: Analysis of safety and effectiveness of NF-RFCA of VAs from left- and right-sided cardiac chambers. MATERIAL AND METHODS: From 2014 to 2018, a group of 128 patients who underwent RFCA of VAs were retrospectively divided into two groups: NF-RFCA and fluoroscopic (F)-RFCA. Patients in each group were then subsequently subdivided into two groups based on VAs localization - left- (LS-Va) and right-sided (RS-Va) VAs. In all patients the CARTO Biosense Webster mapping system was used. RESULTS: In group 1 (NF-RFCA n = 88) 66 (75%) patients underwent RFCA of RS-Va and 22 (25%) of LS-Va. Early success was achieved in 89.8% (n = 79) and long term success in 81.8% (n = 72). In group 2 (F-RFCA n = 40) 19 patients (47.5%) had RFCA of RS-Va and 21 (52.5%) patients of LS-Va. Acute procedural success rate was 80% (n = 32) and long-term success 72.5% (n = 29). There were 4 (4.6%) perioperative complications in NF-RFCA and 2 (5%) in F-RFCA. Success rate, procedure time and complications were not significantly different between groups and subgroups in follow-up. CONCLUSIONS: NF-RFCA in VAs from the right and left cardiac chamber is safe and equally effective as F-RFCA, and it should be implemented as often as possible for protection of patients and electrophysiology staff.

Sphenoid bone and its sinus - anatomo-clinical review of the literature including application to FESS.

Authors paid attention to anatomy and clinical implications which are associated with the variations of the sphenoid sinus. We discuss also anatomical structure of the sphenoid bone implementing clinical application of this bone to different invasive and miniinvasive procedures (i.e. FESS).

Electrode ingrowths revealed during cadaveric dissection of a 5y old implanted pacemaker - the case report.

Increasing numbers of implanted cardiovascular electronic devices, results in a need for lead extractions, which has increased to an annual volume of over 10,000 worldwide. We present a cadaveric dissection body with a single chamber pacemaker implanted 5y before death.

Permanent atrial fibrillation in patients with a dual­chamber pacemaker.

BACKGROUND: Atrial fibrillation (AF) is thought to be a progressive arrhythmia. The impact of sex and position of right ventricular lead is not well recognized. Whilst nonparoxysmal AF compared with paroxysmal AF has been associated with increased mortality in the general population, its prognostic significance nin patients with a dual­chamber (DDD) pacemaker is less clear. AIMS: The aim of the study was to determine the incidence of permanent AF in patients with a DDD pacemaker, analyze the effect of selected baseline characteristics on permanent AF development, and examine the impact of permanent AF on patient survival. METHODS: A retrospective cohort study included 3932 consecutive patients who underwent DDD pacing system implantation between 1984 and 2014. Follow­up was completed in August 2016. We included 3771 patients (96%) with post­operative follow­up and known vital status. Occurrence of permanent AF and all­cause mortality were the study endpoints. RESULTS: During mean follow­up of 6.5 years, permanent AF occurred in 717 patients (19%). Sex (hazard ratio [HR], 1.316; 95% CI, 1.134-1.528, for men), age at implant (HR, 1.041; 95% CI, 1.033-1.049, 1-year increase), history of AF (HR, 3.521; 95% CI, 3.002-4.128) were independently associated with permanent AF development, whereas position of right ventricular lead (apical versus nonapical) and primary pacing indication (atrioventricular block versus sick sinus syndrome) were not related to permanent AF. Permanent AF was a significant risk factor for increased mortality (age- and sex­adjusted HR, 1.475; 95% CI, 1.294-1.682). CONCLUSIONS: Permanent AF occurrence was independently predicted by advanced age at implant, male sex, and preexisting AF and associated with worse survival.