Single-Chamber Leadless Cardiac Pacemaker in Patients Without Atrial Fibrillation: Findings From Campania Leadless Registry

Introduction:Little is known about the clinical performance of single-chamber leadless pacemaker (LLPM) in patients without atrial fibrillation (AF) as pacing indication. The aim of this study was to describe the clinical characteristics of patients who underwent single chamber LLPM implantation at three tertiary referral centers and to compare the safety and effectiveness of the single-chamber LLPM among patients with or without AF.Materials and Methods:All the consecutive patients who underwent LLPM implantation at three referral centers were analyzed. The indications to LLPM in a real-world setting were described. The study population was divided into two groups according to AF as pacing indication. We assessed the procedure-related complications; moreover, we compared syncope, cardiac hospitalization, pacemaker syndrome, and all-cause death recurrence during the follow-up between patients with and without AF as pacing indication.Results:A total of 140 consecutive patients (mean age, 76.7 ± 11.24 years, men 64.3%) were included in the study. The indication to implantation of LLPM was permanent AF with slow ventricular response (n: 67; 47.8%), sinus node dysfunction (n: 25; 17.8%), third atrioventricular block (AVB) (n: 20; 14.2%), second-degree AVB (n: 18; 12.8%), and first degree AVB (n: 10; 7.1%). A total of 7 patients (5%) experienced perioperative complications with no differences between the AF vs. non-AF groups. During a mean follow-up of 606.5 ± 265.9 days, 10 patients (7.7%) died and 7 patients (5.4%) were reported for cardiac hospitalization; 5 patients (3.8%) experienced syncope; no patients showed pacemaker syndrome. No significant differences in the clinical events between the groups were shown. The Kaplan–Meier analysis for the combined endpoints did not show significant differences between the AF and non-AF groups [hazard ratio (HR): 0.94, 95% CI: 0.41–2.16; p = 0.88].Conclusion:Our real-world data suggest that LLPM may be considered a safe and reasonable treatment in patients without AF in need of pacing. Further studies are needed to confirm these preliminary results.

Pacemaker Implantation Via Femoral Vein and Successful Arrhythmia Management in an Elderly Patient with Fontan Circulation: A Case Report

Background The frequency of arrhythmias increases after the Fontan operation over time; atrial tachycardia (AT) and sinus node dysfunction (SND) are frequently observed. Case summary Our patient was 63-year-old woman who underwent a lateral tunnel Fontan operation for double outlet right ventricle at age 36. She experienced paroxysmal AT for one year, and antiarrhythmic medication was not feasible due to symptomatic SND. Computed tomography revealed a 45 mm-sized thrombus in the high right atrium (RA). The patient had three coexisting conditions: paroxysmal AT, symptomatic SND and the RA thrombus, for which total cavopulmonary connection conversion and epicardial PMI would have been effective; however, given her age and comorbidities, surgical treatment was considered high-risk. Catheter ablation was avoided because of the RA thrombus. Finally, a transvenous pacemaker was implanted via the right femoral vein to avoid the RA thrombus and severe venous tortuosity from the left subclavian vein to the RA. After PMI, the patient was prescribed amiodarone and bisoprolol for AT suppression. AT occurred once in the third month after discharge. We increased the dose of amiodarone, and she has been tachycardia-free. Discussion Transvenous PMI must be considered in cases where open thoracic surgery or catheter ablation cannot be performed. This is the first report of transvenous PMI via the right femoral vein and successful AT and SND management in an elderly Fontan patient.

Pacemaker Lead Placement via Transmural Approach in an Adult With Palliated Single Ventricle Heart Disease

Given the lack of systemic venous return to the heart, palliated single ventricle patients frequently require epicardial pacemaker implantation for management of dysrhythmias including sinus node dysfunction, atrial arrhythmias, and heart block. Repeated device hardware replacement, frequently required due to high lead thresholds or other device failure, is a challenging and significant problem for this population. 3-dimensional imaging can assist in delineating the cardiac anatomy allowing for novel approaches to intervention. We review a patient with extracardiac Fontan circulation who underwent placement of an endocardial atrial pacemaker lead via a transmural approach with a 3D-printed model used for procedural guidance.

Dynamical behavior of cardiac conduction system under external disturbances: simulation based on microcontroller technology

The heart rhythm is one of the most interesting aspects of the dynamic behavior of biological systems. Understanding heart rhythms is essential in the dynamic analysis of the heart. Each type of dynamic behaviour can describe normal or pathological physiology. The heart is made up of nodes ranging from SA node (natural pacemaker) to Purkinje fibers. The electric current originates in the sinus node and travels through the heart until it reaches the Purkinje fibers, causing after its passage through each of the nodes a heartbeat thus constituting the electrocardiogram (ECG). Since the origin of the electric current is the sinus node, in this article we study numerically and experimentally by microcontroller the influence of the sinus node on the propagation of electric current through the heart. A study of the sinus node in its autonomous state shows us that in their coupled state, the nodes of the heart qualitatively reproduce the time series of the action potential of this latter, which leads to the recording of the ECG. A study when the sinus node is subjected to periodic pulsed excitation E 1(t) = kP(t), assumed to come from blood pressure, with P(t) the blood pressure, shows that for some selected frequencies, it is found that the nodes of the heart and the ECG exhibit responses having the same shape and the same frequencies as those of the pulsatile blood pressure. This suggests the possibility of using such a conversion and excitation mechanism to replicate the functioning of cardiac conduction system. The chaotic analysis of the sinus node subjected to a sinusoidal type disturbance (E 0sin(ωt)) is also presented, it shows that in its chaotic state, the nodes of the heart, as well as the ECG, provide very high frequency signals. This requires the control of the sinus node (natural pacemaker) in such a situation

Anatomy of the conduction tissues 100 years on: what have we learned?

Knowledge of the anatomy of the ‘conduction tissues’ of the heart is a 20th century phenomenon. Although controversies still continue on the topic, most could have been avoided had greater attention been paid to the original descriptions. All cardiomyocytes, of course, have the capacity to conduct the cardiac impulse. The tissues specifically described as ‘conducting’ first generate the cardiac impulse, and then deliver it in such a fashion that the ventricles contract in orderly fashion. The tissues cannot readily be distinguished by gross inspection. Robust definitions for their recognition had been provided by the end of the first decade of the 20th century. These definitions retain their currency. The sinus node lies as a cigar-shaped structure subepicardially within the terminal groove. There is evidence that it is associated with a paranodal area that may have functional significance. Suggestions of dual nodes, however, are without histological confirmation. The atrioventricular node is located within the triangle of Koch, with significant inferior extensions occupying the atrial vestibules and with septal connections. The conduction axis penetrates the insulating plane of the atrioventricular junctions to continue as the ventricular pathways. Remnants of a ring of cardiomyocytes observed during development are also to be found within the atrial vestibules, particularly a prominent retroaortic remnant, although that their role has still to be determined. Application of the initial criteria for nodes and tracts shows that there are no special ‘conducting tissues’ in the pulmonary venous sleeves that might underscore the abnormal rhythm of atrial fibrillation.

Immediate clinical results of the new biological support ring for correction of mitral insufficiency

Aim. To make the first clinical experience evaluation of the new biological closed support ring for mitral valve.Methods. 26 patients (16 men, 10 women, mean age 55 [49; 62] years) with dysplastic mitral insufficiency were implanted “NEORING” biological ring for the first time from March 2020 to June 2021. The etiological factor of the defect formation in all cases was the connective tissue dysplasia. The mean functional class of heart failure before surgery was 2 [2; 3] according to NYHA, the effective regurgitant orifice (ERO) was 0.4 [0.3; 0.5], vena contracta was 0.7 [0.6; 0.8]. Ten patients received rings of 28 mm diameter, ten patients – 30 mm, six patients – 32 mm.Results. No significant adverse events such as death from any causes, strokes, myocardial infarction, cardiac complications, bleeding, and return of regurgitation or failure of plastic surgery requiring reoperation, infective endocarditis after the intervention were observed. In two cases a permanent pacemaker was implanted due to sinus node dysfunction. At discharge all patients had no regurgitation (ERO 0), medium transvalvular gradient was 4.0 [3.0; 5.3] mm Hg. All the patients were assigned to NYHA functional class I heart failure after the surgery.Conclusion. New biological support ring “NEORING” (“NeoKor”, Kemerovo) use in the middle age group of patients showed high hemodynamic efficiency, the absence of specific complications in the early stages after the surgery. It is planned to expand the clinical material on the use of the biological ring, as well as to evaluate the long-term results in the format of a prospective, randomized trial and compare the new device with the existing ones.

Decreased Heart Rate Variability in COVID-19

On March 12, 2020, the World Health Organization (WHO) announced that the coronavirus disease 2019 (COVID-19) outbreak had become a pandemic. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which primarily infects the lower airways and binds to Angiotensin-Converting Enzyme 2 (ACE2) on alveolar epithelial cells. ACE2 is widely expressed, not only in the lungs but also in the cardiovascular system. Therefore, SARS-CoV-2 can also damage the myocardium. We analysed three COVID-19 cases that resulted in death and found that either COVID-19 or antiviral drugs could affect the coupling between the autonomic nervous system and the sinus node, thus affecting heart rate variability and preventing the heart rate from rising in response to the increase in body temperature. Early detection of the preclinical phase of cardiac autonomic dysfunction may help determine patients in need of aggressive treatment and control of cardiovascular risk factors. Antiviral drugs should be used with caution in patients with heart injury.