Cardiac pacemaker cells located in the sinoatrial node initiate the electrical impulses that drive rhythmic contraction of the heart. The sinoatrial node accounts for only a small proportion of the total mass of the heart yet must produce a stimulus of sufficient strength to stimulate the entire volume of downstream cardiac tissue. This requires balancing a delicate set of electrical interactions both within the sinoatrial node and with the downstream working myocardium. Understanding the fundamental features of these interactions is critical for defining vulnerabilities that arise in human arrhythmic disease and may provide insight towards the design and implementation of the next generation of potential cellular-based cardiac therapeutics. Here, we discuss physiological conditions that influence electrical impulse generation and propagation in the sinoatrial node and describe developmental events that construct the tissue-level architecture that appears necessary for sinoatrial node function.
Background Anger and extreme stress can trigger potentially fatal cardiovascular events in susceptible people. Political elections, such as the 2016 US presidential election, are significant stressors. Whether they can trigger cardiac arrhythmias is unknown. Methods and Results In this retrospective case‐crossover study, we linked cardiac device data, electronic health records, and historic voter registration records from 2436 patients with implanted cardiac devices. The incidence of arrhythmias during the election was compared with a control period with Poisson regression. We also tested for effect modification by demographics, comorbidities, political affiliation, and whether an individual's political affiliation was concordant with county‐level election results. Overall, 2592 arrhythmic events occurred in 655 patients during the hazard period compared with 1533 events in 472 patients during the control period. There was a significant increase in the incidence of composite outcomes for any arrhythmia (incidence rate ratio [IRR], 1.77 [95% CI, 1.42–2.21]), supraventricular arrhythmia (IRR, 1.82 [95% CI, 1.36–2.43]), and ventricular arrhythmia (IRR, 1.60 [95% CI, 1.22–2.10]) during the election relative to the control period. There was also an increase in specific types of arrhythmia, including atrial fibrillation (IRR, 1.50 [95% CI, 1.06–2.11]), supraventricular tachycardia (IRR, 3.7 [95% CI, 2.2–6.2]), nonsustained ventricular tachycardia (IRR, 1.7 [95% CI, 1.3–2.2]), and daily atrial fibrillation burden ( P <0.001). No significant interaction was found for sex, race/ethnicity, device type, age ≥65 years, hypertension, coronary artery disease, heart failure, political affiliation, or concordance between individual political affiliation and county‐level election results. Conclusions There was a significant increase in cardiac arrhythmias during the 2016 US presidential election. These findings suggest that exposure to stressful sociopolitical events may trigger arrhythmogenesis in susceptible people.
Transcatheter aortic valve replacement (TAVR) has developed substantially since its inception. Improvements in valve design, valve deployment technologies, preprocedural imaging and increased operator experience have led to a gradual decline in length of hospitalisation after TAVR. Despite these advances, the need for permanent pacemaker implantation for post-TAVR high-degree atrioventricular block (HAVB) has persisted and has well-established risk factors which can be used to identify patients who are at high risk and advise them accordingly. While most HAVB occurs within 48 hours of the procedure, there is a growing number of patients developing HAVB after initial hospitalisation for TAVR due to the trend for early discharge from hospital. Several observation and management strategies have been proposed. This article reviews major known risk factors for HAVB after TAVR, discusses trends in the timing of HAVB after TAVR and reviews some management strategies for observing transient HAVB after TAVR.
Background As the pandemic continues to unfold, effective, technology‐based solutions are needed to help patients with atrial fibrillation (AF) maintain their health and well‐being during the outbreak of COVID‐19. Methods This single‐center, pilot study investigated the effects of a 4‐week (eight sessions) virtual AF self‐management program. Questionnaires were completed at baseline and 1 week after the intervention, and assessed AF knowledge, adherence to self‐management behaviors, mental health, physical function, and disease‐specific quality of life in patients with AF. Secondary outcomes included knowledge of COVID‐19, intervention, acceptability, and satisfaction. Results Of 68 patients who completed baseline questionnaires, 57 participated in the intervention and were included in the analysis (mean age of 73.4 ± 10.0 years, 60% male). Adherence to AF self‐monitoring behaviors, including monitoring their heart rate (p < .001), heart rhythm (p = .003), and blood pressure (p = .013) were significantly improved at the end of the intervention compared with baseline. Symptom identification (p = .007) and management (p < .001) also improved. Reductions in sleep disturbance (p < .001), anxiety (p = .014), and depression (p = .046) were also observed. Misinformation and inaccurate beliefs about COVID‐19 were significantly reduced at the end of the intervention compared with baseline. Conclusions This pilot study suggests that a virtual patient education program could have beneficial effects on adherence to guideline‐recommend self‐care of AF, emotional wellbeing, physical function, and knowledge of COVID‐19 in patients with AF. Future randomized studies in larger samples are needed to determine the clinical benefits of the intervention.
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