Combined Atrial Volume is Associated with Significant Atrial Arrhythmias in Total Cavopulmonary Connection Fontan Patients.

Atrial arrhythmias are a common late manifestation after Fontan palliation and are known to contribute to significant morbidity and mortality. Atrial volume by cardiac magnetic resonance imaging has been increasingly used in patients with congenital heart disease with no reports in those with Fontan palliation. In acquired heart disease, left atrial volume has been shown to be a strong predictor of outcomes of sustained atrial arrhythmias, including recurrence of atrial fibrillation. We hypothesized that combined atrial volume (CAV) in patients with total cavopulmonary connection (TCPC) Fontan palliation may be associated with increased risk of significant atrial arrhythmias (SAA). This is a single center retrospective case-control study. Cases were defined as patients with TCPC Fontan palliation ≥ 18 years of age, with SAA requiring intervention. Only those with advanced imaging for 3D rendering between 2013 and 2022 were included. CAV was analyzed from a 3-dimensional (3D) data set, including both the left and right atria, excluding the Fontan baffle. Seventeen TCPC Fontan case patients and 17 control patients were included. There was no difference in age between the two groups. There was no difference between gender, type of Fontan palliation, atrio-ventricular valve regurgitation, or combined ventricular function between the two groups. CAV was higher in SAA group compared to controls, and all control patients had indexed CAV ≤ 80 mL/kg. This is the first data suggesting CAV is associated with SAA in TCPC Fontan patients. Indexed CAV ≥ 80 mL/kg may be a valuable marker for SAA risk.

Ventricular Arrhythmic Events After Transcatheter Pulmonary Valve Replacement in Adults with Repaired Tetralogy of Fallot.

Arrhythmias are a major cause of morbidity and mortality in repaired Tetralogy of Fallot (rTOF). However, predicting those at risk for life-threatening ventricular arrhythmias (VA) remains difficult. Many centers approach risk assessment at the time of surgical pulmonary valve intervention. Increasing numbers of patients have undergone transcatheter pulmonary valve replacement (TPVR), yet there are no studies evaluating VA in rTOF undergoing TPVR and the approach to risk assessment for these patients. A single center retrospective study was performed. The institutional interventional database was queried to identify all adults ≥ 18 years of age with rTOF status who underwent TPVR from 2010 to 2019. A total of 81 patients with rTOF underwent TPVR from 2010 to 2019. Mean age at time of TPVR was 27 ± 13 years; follow up after TPVR was 6.4 ± 3.1 years. VA events occurred in 4 patients (5%). There was no significant difference in current era VA risk factors in rTOF patients between the VA event group and the non-VA event group. VA risk in this cohort of rTOF with TPVR was 5%, comparable to that reported in current era surgical cohort with similar follow up. Multi-center agreement on risk assessment protocol is needed for future studies.

Pediatric extracorporeal cardiopulmonary resuscitation for yew cardiotoxicity.

INTRODUCTION: English yew is an evergreen conifer frequently planted in household gardens and, when ingested in large doses, results in severe cardiotoxicity characterized by difficult to control ventricular arrhythmias with high rates of mortality. CASE REPORT: A previously healthy teenage female presented as an out-of-hospital cardiac arrest with refractory ventricular arrhythmias and severe biventricular dysfunction. Due to rapid deterioration in her clinical status, she was cannulated onto venoarterial extracorporeal membrane oxygenation (ECMO) which resulted in rapid normalization of her rhythm and ventricular function. DISCUSSION: Our case highlights the importance of keeping a broad differential diagnosis when considering etiologies of ventricular arrhythmias in the pediatric population. The final diagnosis was not made until after discharge and implantable cardiac defibrillator (ICD) placement. CONCLUSION: The delayed diagnosis of this intentional English yew ingestion ultimately resulted subsequent ICD removal. Early ECMO activation in cases of English yew toxicity can be essential for patient survival.

Percutaneous jugular leadless pacemaker implantation in a pediatric patient.

INTRODUCTION: Leadless cardiac pacing has not been widely utilized in pediatric patients, in part due to concerns regarding size of the delivery sheath and the potential for vascular injury. METHODS: We present a case of leadless pacemaker implantation via internal jugular vein without a surgical cutdown. RESULTS: A leadless pacemaker was successfully implanted in the right ventricle via internal jugular approach in a pediatric patient with congenital heart disease. CONCLUSION: This is a novel approach to leadless pacemaker implantation that could broaden the utilization of this technology to the vulnerable population of children, especially those with congenital heart disease.

A unique mapping strategy for localization and ablation of the atrial input of an antegrade only conducting accessory pathway.

The standard technique for accessory pathway ablation involves mapping along the mitral and tricuspid annulus to localize the regions of earliest ventricular activation during antegrade pathway conduction, earliest atrial activation during retrograde conduction or detection of an accessory pathway potential. In some cases despite what appears to be appropriate mapping, catheter positioning and adequate power delivery the ablation is not successful. In many of these cases, the pathway is felt to be inaccessible because of a location remote from the mitral or tricuspid annulus that cannot be affected by endocardial power delivery along the annulus. In the case of difficult left sided pathways, some may be reached and ablated via the coronary sinus or its branches. Right sided pathways cannot be approached in this fashion since there is no venous structure analogous to the coronary sinus around the tricuspid annulus. Alternative mapping and ablation techniques for these difficult pathways have included epicardial mapping via direct pericardial access or attempts to localize pathway insertion areas remote from the valve annulus which may be amenable to endocardial ablation. We describe the use of post-pacing interval mapping to localize the atrial input of a right sided antegrade only accessory pathway that was resistant to conventional mapping and ablation strategies.

Reclassification of Variants of Uncertain Significance in Children with Inherited Arrhythmia Syndromes is Predicted by Clinical Factors.

Genetic testing is important to augment clinical diagnosis and inform management of inherited arrhythmias syndromes (IAS), but variants of uncertain significance (VUS) are common and remain a challenge in clinical practice. In 2015, American College of Medical Genetics (ACMG) published updated guidelines for interpretation of genetic results. Despite increasing understanding of human genomic variation, there are no guidelines for reinterpretation of prior genetic test results. Patients at a single tertiary children's hospital with genetic testing for an IAS that demonstrated a VUS were re-evaluated using 2015 ACMG guidelines, clinical information, and publically available databases. Search of the electronic medical record identified 116 patients with genetic testing results available, and 24/116 (21%) harbored a VUS for an IAS. 23 unique VUS were evaluated from 12 genes. Over half of the VUS (12/23 (52%)) were reclassified using 2015 criteria, and 8 (35%) changed to pathogenic and 4 (17%) to benign. Relative risk of reclassification of VUS to a pathogenic variant in a patient with confirmed clinical diagnosis was 4.1 (95% CI 1.23-15.4). Reclassification was not associated with initial testing year. These data demonstrate 52% of VUS in children with IAS are reclassified with application of 2015 ACMG guidelines. Strength of phenotyping is associated with eventual pathogenic classification of genetic variants and periodic re-evaluation of VUS identified on genetic testing for IAS is warranted.

Cilia gene mutations cause atrioventricular septal defects by multiple mechanisms.

Atrioventricular septal defects (AVSDs) are a common severe form of congenital heart disease (CHD). In this study we identified deleterious non-synonymous mutations in two cilia genes, Dnah11 and Mks1, in independent N-ethyl-N-nitrosourea-induced mouse mutant lines with heritable recessive AVSDs by whole-exome sequencing. Cilia are required for left/right body axis determination and second heart field (SHF) Hedgehog (Hh) signaling, and we find that cilia mutations affect these requirements differentially. Dnah11avc4 did not disrupt SHF Hh signaling and caused AVSDs only concurrently with heterotaxy, a left/right axis abnormality. In contrast, Mks1avc6 disrupted SHF Hh signaling and caused AVSDs without heterotaxy. We performed unbiased whole-genome SHF transcriptional profiling and found that cilia motility genes were not expressed in the SHF whereas cilia structural and signaling genes were highly expressed. SHF cilia gene expression predicted the phenotypic concordance between AVSDs and heterotaxy in mice and humans with cilia gene mutations. A two-step model of cilia action accurately predicted the AVSD/heterotaxyu phenotypic expression pattern caused by cilia gene mutations. We speculate that cilia gene mutations contribute to both syndromic and non-syndromic AVSDs in humans and provide a model that predicts the phenotypic consequences of specific cilia gene mutations.

MATR3 disruption in human and mouse associated with bicuspid aortic valve, aortic coarctation and patent ductus arteriosus.

Cardiac left ventricular outflow tract (LVOT) defects represent a common but heterogeneous subset of congenital heart disease for which gene identification has been difficult. We describe a 46,XY,t(1;5)(p36.11;q31.2)dn translocation carrier with pervasive developmental delay who also exhibited LVOT defects, including bicuspid aortic valve (BAV), coarctation of the aorta (CoA) and patent ductus arteriosus (PDA). The 1p breakpoint disrupts the 5' UTR of AHDC1, which encodes AT-hook DNA-binding motif containing-1 protein, and AHDC1-truncating mutations have recently been described in a syndrome that includes developmental delay, but not congenital heart disease [Xia, F., Bainbridge, M.N., Tan, T.Y., Wangler, M.F., Scheuerle, A.E., Zackai, E.H., Harr, M.H., Sutton, V.R., Nalam, R.L., Zhu, W. et al. (2014) De Novo truncating mutations in AHDC1 in individuals with syndromic expressive language delay, hypotonia, and sleep apnea. Am. J. Hum. Genet., 94, 784-789]. On the other hand, the 5q translocation breakpoint disrupts the 3' UTR of MATR3, which encodes the nuclear matrix protein Matrin 3, and mouse Matr3 is strongly expressed in neural crest, developing heart and great vessels, whereas Ahdc1 is not. To further establish MATR3 3' UTR disruption as the cause of the proband's LVOT defects, we prepared a mouse Matr3(Gt-ex13) gene trap allele that disrupted the 3' portion of the gene. Matr3(Gt-ex13) homozygotes are early embryo lethal, but Matr3(Gt-ex13) heterozygotes exhibit incompletely penetrant BAV, CoA and PDA phenotypes similar to those in the human proband, as well as ventricular septal defect (VSD) and double-outlet right ventricle (DORV). Both the human MATR3 translocation breakpoint and the mouse Matr3(Gt-ex13) gene trap insertion disturb the polyadenylation of MATR3 transcripts and alter Matrin 3 protein expression, quantitatively or qualitatively. Thus, subtle perturbations in Matrin 3 expression appear to cause similar LVOT defects in human and mouse.

Outcomes following the implantation of cardioverter-defibrillator for primary prevention in transposition of the great arteries after intra-atrial baffle repair: a single-centre experience.

AIMS: Patients with D-loop transposition of the great arteries (D-TGA) status post intra-atrial baffling are at an increased risk for sudden cardiac arrest. The benefit of primary implantable cardioverter-defibrillator (ICD) implantation in these patients is questionable due to high burden of adverse events. We aimed to evaluate the incidence and causes of all types of device shocks, as well as of device-related complications among patients with D-TGA implanted with ICDs for primary prevention. METHODS AND RESULTS: Retrospective analysis of all patients with D-TGA who underwent atrial switch procedure and ICD implantation for primary prevention. Eighteen patients (83% males) were identified. Average age at atrial switch was 2.5 years (range 0.1-17) and at ICD implantation 26 years (15-41). During a median follow-up of 4 years, 10 patients (55%) received shocks for non-ventricular arrhythmic events, whereas 1 patient was shocked for ventricular tachycardia, for an annual rate of shock delivery of 7.1%. The most common cause for shock delivery was the occurrence of atrial arrhythmias, mostly in the form of atrial flutter. Elevated systemic ventricular end-diastolic pressures were found to be associated with an increased risk for inappropriate shocks. Five patients (28%) required lead extraction and three required generator change due to device recalls during follow-up. CONCLUSION: Atrial arrhythmias were the most common cause for ICD shocks in a primary prevention population, while ventricular tachycardia was infrequent. The association between elevated end-diastolic pressures and the occurrence of arrhythmias demonstrates the close mechano-electrical relationship in D-TGA and may be an important predictor of arrhythmic events.

An international multicenter cohort study on implantable cardioverter-defibrillators for the treatment of symptomatic children with catecholaminergic polymorphic ventricular tachycardia.

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) may cause sudden cardiac death (SCD) despite medical therapy. Therefore, implantable cardioverter-defibrillators (ICDs) are commonly advised. However, there is limited data on the outcomes of ICD use in children. OBJECTIVE: The purpose of this study was to compare the risk of arrhythmic events in pediatric patients with CPVT with and without an ICD. METHODS: We compared the risk of SCD in patients with RYR2 (ryanodine receptor 2) variants and phenotype-positive symptomatic CPVT patients with and without an ICD who were younger than 19 years and had no history of sudden cardiac arrest at phenotype diagnosis. The primary outcome was SCD; secondary outcomes were composite end points of SCD, sudden cardiac arrest, or appropriate ICD shocks with or without arrhythmic syncope. RESULTS: The study included 235 patients, 73 with an ICD (31.1%) and 162 without an ICD (68.9%). Over a median follow-up of 8.0 years (interquartile range 4.3-13.4 years), SCD occurred in 7 patients (3.0%), of whom 4 (57.1%) were noncompliant with medications and none had an ICD. Patients with ICD had a higher risk of both secondary composite outcomes (without syncope: hazard ratio 5.85; 95% confidence interval 3.40-10.09; P < .0001; with syncope: hazard ratio 2.55; 95% confidence interval 1.50-4.34; P = .0005). Thirty-one patients with ICD (42.5%) experienced appropriate shocks, 18 (24.7%) inappropriate shocks, and 21 (28.8%) device-related complications. CONCLUSION: SCD events occurred only in patients without an ICD and mostly in those not on optimal medical therapy. Patients with an ICD had a high risk of appropriate and inappropriate shocks, which may be reduced with appropriate device programming. Severe ICD complications were common, and risks vs benefits of ICDs need to be considered.

Implanted defibrillators in young hypertrophic cardiomyopathy patients: a multicenter study.

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease, with an annual risk of sudden cardiac death (SCD) estimated at 1 %. Limited data are available regarding both the risk of SCD in the young HCM population and the use of implantable cardioverter-defibrillators (ICDs). This retrospective study included all patients with HCM who underwent ICD implantation for primary or secondary prevention of SCD before the age of 30 years at five institutions between 1995 and 2009. There were 99 devices implanted in 73 patients. Appropriate shocks occurred for 11 % of all the patients. None of the previously identified conventional risk factors for SCD in HCM patients were associated with increased risk of appropriate shocks in the young study cohort. During a median follow-up period of 2.4 years, inappropriate shocks occurred for 22 % of the patients. Older age at implant was associated with a decreased risk of inappropriate shock. Those who underwent implantation in the earlier decade had a higher incidence of inappropriate shocks. Late complications including lead fracture or dislodgement, generator malfunction, and infection occurred for 32 % of the patients. Three patients died (4 %), one of whom had an arrhythmic sudden death. A greater proportion of primary prevention implantations was performed for patients from the latter decade. Over time, ICD use in young HCM patients has become increasingly primary prevention oriented. Shock rates mirror those reported in adult series, and there is a substantial incidence of device complications.

Atrial Arrhythmias in Adults with Fontan Palliation.

Single ventricle physiology is a rare form of congenital heart disease and was, historically, a uniformly lethal condition. However, the atriopulmonary Fontan operation, and its successive iterations, the lateral tunnel and extracardiac conduit Fontan, became the fundamental approach to treating single ventricle heart disease. Over time, dysrhythmias are some of the most common complications with Fontan physiology, compounding morbidity and mortality. Atrial arrhythmias are prevalent in the Fontan population and occur in about 15-60% of patients with Fontan palliation, increasingly with age. Diagnosing atrial arrhythmias in patients with Fontan palliation may be challenging because of low voltage amplitudes arising from myopathic atrial tissue making it difficult to clearly assess atrial depolarization on surface electrocardiograms (ECG), vague symptoms not suggestive of tachyarrhythmia, or atrial arrhythmia with ventricular rates below 100 beats per minute. Intra-atrial reentrant tachycardia (IART) is the most common type of supraventricular tachycardia in adults with Fontan palliation. Acute management of atrial arrhythmias in patients with Fontan palliation involves prompt assessment of a patient's hemodynamic stability, anticoagulation and thrombosis risk, systemic ventricular function, and risk of sedation or anesthesia if needed. Long-term management of atrial arrhythmias is often multifactorial and may include long-term anti-arrhythmic therapy, permanent pacing, and ablation. The best approach for the management of atrial arrhythmias in adults with Fontan palliation is patient-specific and involves collaboration between congenital electrophysiologists, adult congenital cardiologists, and the patient.

Interrogating the pill: Rising distrust and the reshaping of health risk perceptions in the social media age.

Since its introduction in 1960, the combined oral contraceptive pill has become the dominant reversible contraceptive technology for controlling female fertility in spite of early and ongoing ethical, critical medical, and societal disapproval. Over the last decade, prescription rates among young women in Western Europe have declined alongside the rise of social media use. This article investigates the mechanisms underlying this change in contraceptive choices and the role played by social media in this trend. Via exploratory online observation and an in-depth interview study with 19 informants in Germany and Denmark, we find social media consolidates the social construction of hazards associated with the contraceptive pill by reshaping young women's risk perception from questions around drug reliability and safety to those of individual physical, mental, and social well-being. We shed light on how social media contributes to the delegitimation of health professionals such as gynaecologists and general practitioners and adds to wider debates on the erosion of medical authority and the attendant rise of peer influencers. We condense our findings into a framework for health-related attitude formation and decision-making in the social media age, which elucidates how social media amplifies and reshapes societal discourses regarding health-related technologies, choices, and risks.

Beyond Anatomy: Use of Sinus Propagation Mapping to Identify the Slow Pathway for Cryoablation in Pediatric Patients.

Slow pathway modification via cryoablation is a common treatment of atrioventricular nodal re-entrant tachycardia (AVNRT) in pediatric patients. Sinus propagation mapping (SPM) is a tool that has been used to augment identification of the AVNRT slow pathway. We hypothesize that the use of SPM will decrease the total number of ablations performed and decrease the number of ablations until the slow pathway is successfully modified without a significant increase in procedure time. We conducted a retrospective review of patients who underwent cryoablation for AVNRT from August 2016 through March 2021. We excluded patients >21 years of age, those who underwent radiofrequency ablation; those with prior AVNRT ablation, additional pathways, or arrhythmias; and those with congenital heart disease. Out of 122 patients identified by the IMPACT database query, 103 met the inclusion criteria. Fifty-two patients (50.5%) had SPM completed during their procedures. The median number of ablations needed until successful slow pathway modification was two ablations in patients who underwent SPM and four ablations in the non-SPM group (P = .03). There was no significant difference in the total number of ablations between groups. The median total procedural time was longer in the SPM group (152 vs. 125 min; P = .01). SPM can be utilized to further improve the successful treatment of AVNRT with cryotherapy by lowering the number of ablations needed until successful slow pathway modification. However, the technique requires some additional time to collect sufficient data points to create the sinus map.

Patientology revisited: Toward tailored care pathways.

BACKGROUND: Concepts such as patient-centred care, patient empowerment and patient participation have challenged our understanding of what it means to be a patient and what role patients play in care pathways. Consequently, patientology as the medical sociological and anthropological study of patients is currently being reconceptualized through perspectives of health as individualized and privatized capital. AIMS: This article explores the potential of such a patientological perspective to enhance our understanding of and tailor care pathways. Particularly, we aim to investigate how such a perspective can contribute to tailoring care pathways to the capacities of individual patients and their relatives. MATERIALS & METHODS: We elaborate on an emerging health capital-theoretic model for patientology and study its potential for optimizing care pathways through two distinct cases of care contexts: communicative challenges in the context of integrative primary care for vulnerable chronically ill multi-morbid patients and the potential of parent involvement in the acute hospitalization of children suspected to be affected by multisystem inflammatory syndrome in children. RESULTS: Our results shed light on the importance of cultural and social capital of patients and their relatives in the design of effective tailored care pathways. We find that a lack of cultural and social capital presents a significant barrier to effective communication between patients and the healthcare professionals involved in their care pathways. We also find that understanding the cultural and social capital of relatives provides an entry point to their effective involvement in the care pathways of their children. DISCUSSION & CONCLUSION: The implications of these findings extend beyond the concrete care contexts studied. This article contributes to our understanding of care pathways through a perspective of health inequalities being based on differences in health capital and demonstrates how the health capital-theoretic patientology model facilitates the systematic development of guidelines for healthcare professionals to assess patients' resources and tailor their care pathways accordingly.

Heart-to-heart with ChatGPT: the impact of patients consulting AI for cardiovascular health advice.

OBJECTIVES: The advent of conversational artificial intelligence (AI) systems employing large language models such as ChatGPT has sparked public, professional and academic debates on the capabilities of such technologies. This mixed-methods study sets out to review and systematically explore the capabilities of ChatGPT to adequately provide health advice to patients when prompted regarding four topics from the field of cardiovascular diseases. METHODS: As of 30 May 2023, 528 items on PubMed contained the term ChatGPT in their title and/or abstract, with 258 being classified as journal articles and included in our thematic state-of-the-art review. For the experimental part, we systematically developed and assessed 123 prompts across the four topics based on three classes of users and two languages. Medical and communications experts scored ChatGPT's responses according to the 4Cs of language model evaluation proposed in this article: correct, concise, comprehensive and comprehensible. RESULTS: The articles reviewed were fairly evenly distributed across discussing how ChatGPT could be used for medical publishing, in clinical practice and for education of medical personnel and/or patients. Quantitatively and qualitatively assessing the capability of ChatGPT on the 123 prompts demonstrated that, while the responses generally received above-average scores, they occupy a spectrum from the concise and correct via the absurd to what only can be described as hazardously incorrect and incomplete. Prompts formulated at higher levels of health literacy generally yielded higher-quality answers. Counterintuitively, responses in a lower-resource language were often of higher quality. CONCLUSIONS: The results emphasise the relationship between prompt and response quality and hint at potentially concerning futures in personalised medicine. The widespread use of large language models for health advice might amplify existing health inequalities and will increase the pressure on healthcare systems by providing easy access to many seemingly likely differential diagnoses and recommendations for seeing a doctor for even harmless ailments.

Rationale and Design of the Multicenter Catheter Ablation of Ventricular Tachycardia Before Transcatheter Pulmonary Valve Replacement in Repaired Tetralogy of Fallot Study.

Patients with repaired tetralogy of Fallot are at elevated risk for ventricular arrhythmia and sudden cardiac death. Over the past decade, the pathogenesis and natural history of ventricular tachycardia has become increasingly understood, and catheter ablation has emerged as an effective treatment modality. Concurrently, there has been great progress in the development of a versatile array of transcatheter valves that can be placed in the native right ventricular outflow tract for the treatment of long-standing pulmonary regurgitation. Although such valve platforms may eliminate the need for repeat cardiac operations, they may also impede catheter access to the myocardial substrates responsible for sustained macro-reentrant ventricular tachycardia. This manuscript provides the rationale and design of a recently devised multicenter study that will examine the clinical outcomes of a uniform, preemptive strategy to eliminate ventricular tachycardia substrates before transcatheter pulmonary valve implantation in patients with tetralogy of Fallot.

Genome-wide identification of mouse congenital heart disease loci.

Empirical evidence supporting a genetic basis for the etiology of congenital heart disease (CHD) is limited and few disease-causing mutations have been identified. To identify novel CHD genes, we performed a forward genetic screen to identify mutant mouse lines with heritable CHD. Lines with recessive N-ethyl-N-nitrsourea-induced CHD-causing mutations were identified using a three-generation backcross. A hierarchical screening protocol was used to test the hypothesis that the fetal-to-neonatal circulatory transition unmasks the specific structural heart defects observed in CHD. Mice with heart defects were efficiently ascertained by selecting for pups exhibiting perinatal lethality and characterizing their cardiac pathology. A marked increase of perinatal lethality was observed in the mutagen-treated cohort compared with an untreated backcross population. Cardiac pathology on perinatal lethals revealed cardiovascular defects in 79 pups from 47 of 321 mutagenized lines. All identified structural abnormalities were analogous to previously described forms of human CHD. Furthermore, the phenotypic recurrence and variance patterns across all lines were similar to human CHD prevalence and recurrence patterns. We mapped the locus responsible for heritable atrioventricular septal defects in six lines (avc1-6). Our screen demonstrated that 'sporadic' CHD may have major genetic component and established a practical, efficient approach for identifying CHD candidate genes.

COVID-19 Vaccine Hesitancy in Denmark and Russia: A qualitative typology at the nexus of agency and health capital.

Vaccination of the world population is being embraced by 184 countries as the main strategy to end the COVID-19 pandemic; vaccination rates are stalling even in countries with high vaccine availability, though. This article investigates the phenomenon of vaccine hesitancy in two such countries, the Kingdom of Denmark and the Russian Federation, through a qualitative study of the different types of hesitancy to COVID-19 vaccination programs and their underlying mechanisms. The analysis reveals a typology along the dimensions of agency and health capital: resisting hesitancy based on mistrust of authority, paralyzed hesitancy based on personal fear, informed hesitancy based on informed choice, and empowered hesitancy based on empowered choice. While the mechanisms underlying vaccine hesitancy are to a great extent comparable between the two countries, differences in population size, societal cohesion, and political culture seem to impact the prevalence and severity of types and, thereby, the outcomes of national COVID-19 vaccination programs and national campaigns for mitigating COVID-19 vaccine hesitancy. The implications of these findings extend beyond the particular context of COVID-19 and the countries studied, supporting and nuancing existing models for vaccine hesitancy, as well as providing a starting point for tailored campaigns for mitigating vaccine hesitancy.

Catheter Ablation of Atrial Arrhythmias in Patients Post-Fontan.

Atrial arrhythmias are highly prevalent in the aging Fontan population and contribute importantly to morbidity and mortality. Although the most common arrhythmia is scar-based intra-atrial re-entrant tachycardia, various other arrhythmias may occur, including focal atrial tachycardia, atrioventricular node-dependent tachycardias, and atrial fibrillation. The type and prevalence of atrial arrhythmia is determined, in part, by the underlying congenital defect and variant of Fontan surgery. Although the cumulative incidence of atrial tachyarrhythmias has decreased substantially from the atriopulmonary anastomosis to the more recent total cavopulmonary-connection Fontan, the burden of atrial arrhythmias remains substantial. Management is often multifaceted and can include anticoagulation, anti-arrhythmic drug therapy, pacing, and cardioversion. Catheter ablation plays a key role in control of arrhythmia. Risks and benefits must be carefully weighed. Among the important considerations are the clinical burden of arrhythmia, ventricular function, hemodynamic stability in tachycardia, suspected arrhythmia mechanisms, risks associated with anaesthesia, venous access, approaches to reaching the pulmonary venous atrium, and accompanying comorbidities. Careful review of surgical notes, electrocardiographic tracings, and advanced imaging is paramount, with particular attention to anatomic abnormalities such as venous obstructions and displaced conduction systems. Despite numerous challenges, ablation of atrial arrhythmias is effective in improving clinical status. Nevertheless, onset of new arrhythmias is common during long-term follow-up. Advanced technologies, such as high-density mapping catheters and remote magnetic guided ablation, carry the potential to further improve outcomes. Fontan patients with atrial arrhythmias should be referred to centres with dedicated expertise in congenital heart disease including catheter ablation, anaesthesia support, and advanced imaging.