The impact of supraventricular arrhythmias on the outcomes of guideline-compliant implantable cardioverter defibrillator programming.

INTRODUCTION: Several implantable cardioverter defibrillators (ICD) programming strategies are applied to minimize ICD therapy, especially unnecessary therapies from supraventricular arrhythmias (SVA). However, it remains unknown whether these optimal programming recommendations only benefit those with SVAs or have any detrimental effects from delayed therapy on those without SVAs. This study aims to assess the impact of SVA on the outcomes of ICD programming based on 2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement and 2019 focused update on optimal ICD programming and testing guidelines. METHODS: Consecutive patients who underwent ICD insertion for primary prevention were classified into four groups based on SVA status and ICD programming: (1) guideline-concordant group (GC) with SVA, (2) GC without SVA, (3) nonguideline concordant group (NGC) with SVA, and (4) NGC without SVA. Cox proportional hazard models were analyzed for freedom from ICD therapies, shock, and mortality. RESULTS: Seven hundred and seventy-two patients (median age, 64 years) were enrolled. ICD therapies were the most frequent in NGC with SVA (24.0%), followed by NGC without SVA (19.9%), GC without SVA (11.6%), and GC with SVA (8.1%). Guideline concordant programming was associated with 68% ICD therapy reduction (HR 0.32, p = .007) and 67% ICD shock reduction (HR 0.33, p = .030) in SVA patients and 44% ICD therapy reduction in those without SVA (HR 0.56, p = .030). CONCLUSION: Programming ICDs in primary prevention patients based on current guidelines reduces therapy burden without increasing mortality in both SVA and non-SVA patients. A greater magnitude of reduced ICD therapy was found in those with supraventricular arrhythmias.

An objective tool for quantifying atrial fibrillation substrate in rats.

The utility of rodents for research related to atrial fibrillation (AF) is growing exponentially. However, the obtained arrhythmic waveforms are often mixed with ventricular signals and the ability to analyze regularity and complexity of such events is limited. Recently, we introduced an implantable quadripolar electrode adapted for advanced atrial electrophysiology in ambulatory rats. Notably, we have found that the implantation itself leads to progressive atrial remodeling, presumably because of mechanical loading of the atria. In the present study, we developed an algorithm to clean the atrial signals from ventricular mixing and thereafter quantify the AF substrate in an objective manner based on waveform complexity. Rats were sequentially examined 1-, 4-, and 8-wk postelectrode implantation using a standard AF triggering protocol. Preburst ventricular mixing was sampled and automatically subtracted based on QRS detection in the ECG. Thereafter, the "pure" atrial signals were analyzed by Lempel-Ziv complexity algorithm and a complexity ratio (CR) was defined for each signal by normalizing the postburst to the preburst values. Receiver operating characteristic (ROC) curve analysis indicated an optimal CR cutoff of 1.236 that detected irregular arrhythmic events with high sensitivity (94.5%), specificity (93.1%), and area under the curve (AUC) (0.96, 95% confidence interval, 0.945-0.976). Automated and unbiased analysis indicated a gradual increase in signal complexity over time with augmentation of high frequencies in power spectrum analysis. Our findings indicate that CR algorithm detects irregularity in a highly efficient manner and can also detect the atrial remodeling induced by electrode implantation. Thus, CR analysis can strongly facilitate standardized AF research in rodents.NEW & NOTEWORTHY Rodents are increasingly used in AF research. However, because of technical difficulties including atrial waveform mixing by ventricular signals, most studies do not discriminate between irregular (i.e., AF) and regular atrial arrhythmias. Here, we develop an unbiased computerized tool to "pure" the atrial signals from ventricular mixing and thereafter analyze AF substrate based on the level of irregularity in an objective manner. This novel tool can facilitate standardized AF research in rodents.

Radiofrequency ablation of supraventricular arrhythmias after orthotopic heart transplantation: Long-term follow-up of a single-center experience.

BACKGROUND: Supraventricular arrhythmias (SVAs), commonly managed with radiofrequency ablation (RFA), may occur after orthotopic heart transplantation (OHT). METHODS: We retrospectively assessed 514 consecutive patients (pts.) undergoing OHT between January 1990 and July 2016 in a single-center. Patients with SVAs managed with RFA were included. Mechanisms of genesis of SVAs, association with surgical techniques and outcomes, were analyzed. RESULTS: Of 514 pts undergoing OHT, 53% (272 pts.) were managed with bicaval (BC) technique and 47% (242 pts.) with biatrial (BA) technique. Mean follow-up 10 ± 8.4 years. Nine pts. (1.7%) developed SVA requiring RFA. The BC technique was performed in 4 pts., 3 pts. presented cavotricuspid isthmus-dependent atrial flutter (CTI AFL), and 1 pt. double loop AFL. Five pts. were managed with BA technique, 4 pts. presented CTI AFL, and 1 pt. atrial tachycardia (AT). Mean time between OHT and SVA occurrence was 6.6 ± 5.5 years. The procedure was successful in 89% (8 pts.). Arrhythmia recurrence was seen in 3 pts (37%), all with BA technique. CONCLUSION: Supraventricular arrhythmias in heart transplantation may be associated with the surgical scar. Identifying the mechanism is vital to choose the appropriate treatment with radiofrequency ablation.

Oral administration of MnCl2 attenuated hyperlipidemia-related cardiac remodeling in ApoE-/- mice.

Manganese chloride (MnCl2) has been shown to inhibit the Yes-associated protein (YAP) in high-fat diet-fed ApoE-/- mice. Although YAP has been implicated in atherogenesis, there are limited data on the effects of MnCl2 on cardiac remodeling. In this study, we discovered, by electrocardiography, that hyperlipidemia led to spontaneous supraventricular arrhythmia (SVA) in ApoE-/- (KO) mice, with 3 of 9 KO + MnCl2 mice (33%) exhibiting lower incidence of spontaneous SVA than KO mice (6 of 10 mice, 60%). Echocardiography revealed that reduced systolic function in KO mice was reversed by MnCl2 treatment. Oil Red O staining of the aortas and biochemical analysis of lipid levels showed that MnCl2 inhibited plaque formation in a lipid metabolism-independent manner. MnCl2 inhibited inflammatory cell infiltration and reduced fibrosis, as evidenced by hematoxylin and eosin, immunohistochemical and Masson's trichrome staining, respectively. Our findings demonstrate that spontaneous SVA and reduced systolic function were blocked by MnCl2. Our findings show that MnCl2 was useful in delaying cardiac remodeling and reducing susceptibility to spontaneous SVA in a mouse model of hyperlipidemia.

Swallowing-induced supraventricular arrhythmia: A different perspective to mechanism.

Atypical presentations of supraventricular arrhythmias constitute a diagnostic challenge which are not frequently reported in literature. Swallowing-induced supraventricular arrhythmia (SI-SVA), which was first described in 1926, is an intriguing presentation of supraventricular tachycardia and occurs during a wet or solid swallow. A 67-year-old man presented to our outpatient clinic complaining from recurrent episodes of sensation of palpitations and short duration pressure on his chest while swallowing since the last 2 weeks. Ambulatory rhythm Holter monitoring was suggestive of atrial fibrillation (AF) or atrial tachycardia attacks during swallowing. In addition, electrocardiography performed during solid food swallowing, showed short duration of AF consistent with the patient's symptoms. The patient was successfully treated with amiodarone. The main cause of SI-SVA is not known. Cross-talk of nerves during the impulse propagation might be the underlying cause of this phenomenon.

Vasopressin in Patients with Septic Shock and Dynamic Left Ventricular Outflow Tract Obstruction.

PURPOSE: Left ventricular outflow tract obstruction (LVOTO) is a relatively uncommon but severe condition that may lead to hemodynamic impairment. It can be elicited by morphological (left ventricular hypertrophy, sigmoid septum, prominent papillary muscle, prolonged anterior mitral valve leaflet) and functional (hypovolemia, low afterload, hypercontractility, catecholamines) factors. We sought to determine the incidence of the most severe form of LVOTO in septic shock patients and describe the therapeutic effects of vasopressin. METHODS: Over a period of 29 months, 527 patients in septic shock were screened for LVOTO. All were mechanically ventilated and treated according to sepsis bundles, including pre-load optimization and norepinephrine infusion. Vasopressin was added in addition to norepinephrine to reduce the adrenergic burden and decrease LVOTO. RESULTS: Ten patients were diagnosed with the most severe form of LVOTO, including systolic anterior mitral valve motion (SAM) and severe mitral regurgitation (MR) with pulmonary oedema. The median norepinephrine dosage to obtain a mean arterial pressure of ≥70 mmHg was 0.58 mcg/Kg/min (IQR 0.40-0.78). All patients had a hyper-contractile left ventricle, septal hypertrophy, significant LVOTO (peak gradient 78 [56-123] mmHg) associated with SAM and severe MR with pulmonary oedema. Vasopressin (median 4 IU/h) allowed a significant reduction of norepinephrine (0.18 [0.14-0.30] mcg/kg/min; p = 0.01), LVOT gradient (35 [24-60] mmHg; p = 0.01) and MR with a significant paO2/FiO2 increase (174 [125-213] mmHg; p = 0.01). CONCLUSION: Vasopressin allowed a reduction of norepinephrine with subsequent LVOTO reduction and hemodynamic improvement of the most severe form of LVOTO, which represented 1.9% of all septic shock patients.

Landiolol for managing post-operative atrial fibrillation.

Beta-blockers are a potential option to manage peri-operative atrial fibrillation. Landiolol is a new ultra-short beta-blocker with a half-life of only 4 minutes and very high beta-1 selectivity which has been used for treatment and prevention of atrial fibrillation in pulmonary surgery and gastro-intestinal surgery. Due to its limited negative inotropic effect and high beta-1 selectivity landiolol allows for control of heart rate with minimal impact on blood pressure. Landiolol is well tolerated by the respiratory system. Additional benefits are related to the regulation of the inflammatory response and blunting of the adrenergic pathway. There is a limited number of trials with total of 61 patients undergoing lung resection or oesophagectomy who developed post-operative atrial fibrillation and were treated with landiolol. The experience with landiolol for prevention is more documented than landiolol application for treatment of post-operative atrial fibrillation. There are 9 comparative studies with a total of 450 patients administered landiolol for prevention of post-operative atrial fibrillation. The use of low dosage (5-10mcg/kg/min) is usually sufficient to rapidly control heart rate which is associated with earlier and higher rate of conversion to sinus rhythm as compared to the controls. The excellent tolerance of landiolol at lower dosage (3-5mcg/kg/min) allows to initiate prophylactic use during surgery and postoperatively. Landiolol prophylaxis is associated with reduced incidence of post-operative atrial fibrillation without triggering adverse events related to a beta-blockade.

Landiolol for managing atrial fibrillation in intensive care.

Landiolol is an injectable ultrashort acting beta-blocker with high beta1 selectivity indicated for heart rate control of atrial fibrillation in the emergency and critical care setting. Accordingly, landiolol is associated with a significantly reduced risk of arterial hypotension and negative inotropic effects. Based on this particular profile along with the clinical experience in Japan for more than a decade landiolol represents a promising agent for the management of elevated heart rate and atrial fibrillation in intensive care patients even with catecholamine requirements. This article provides a review and perspective of landiolol for heart rate control in intensive care patients based on the current literature.

Incidence, Risk Factors and Outcomes of New Onset Supraventricular Arrhythmias in African American Patients with Severe Sepsis.

PURPOSE: New onset supraventricular arrhythmias (SVA) are commonly reported in mixed intensive care settings. We sought to determine the incidence, risk factors and outcomes of new onset SVA in African American (AA) patients with severe sepsis admitted to medical intensive care unit (MICU). METHODS: Patients admitted to MICU between January 2012 through December 2012 were studied. Patients with a previous history of arrhythmia or with new onset of ventricular arrhythmia were excluded. Data on risk factors, critical care interventions and outcomes were obtained. RESULTS: One hundred and thirty-one patients were identified. New onset SVA occurred in 34 (26%) patients. Of those 34, 20 (59%) had atrial fibrillation (AF), 6 (18%) had atrial flutter and 8 (24%) had other forms of SVA. Compared with patients without SVA, patients with new onset SVA were older (69 ± 12 yrs vs 59 ± 13 yrs, P=.003), had congestive heart failure (47% vs 24%, P=.015) and dyslipidemia (41% vs 15%, P=.002). Additionally, they had a higher mean mortality prediction model (MPM II) score (65 ± 25 vs 49 ± 26, P=.001) and an increased incidence of respiratory failure (85% vs 55%, P=.001). Hospital mortality in patients with new onset SVA was 18 (53%) vs 30 (31%); P=.024; however, in a multivariate analysis, new onset SVA was associated with non-significantly increased odds (OR 2.58, 95% CI 0.86-8.05) for in-hospital mortality. CONCLUSIONS: New onset SVA was prevalent in AA patients with severe sepsis and occurred more frequently with advanced age, increased severity of illness, congestive heart failure, and acute respiratory failure; it was associated with higher unadjusted in hospital mortality. However, after multiple adjustments, new onset SVA did not remain an independent predictor of mortality.

The Management of Supraventricular Tachyarrhythmias in Patients with Pulmonary Arterial Hypertension.

BACKGROUND: Atrial remodelling in pulmonary arterial hypertension (PAH) may lead to higher incidence of supraventricular arrhythmias (SVA). The purpose of this study was to evaluate the efficiency and safety of various methods for treatment of SVA in this group. METHODS: This was a single centre study. Forty-eight patients (33 women and 15 men) aged 19-77 years (median 49 years) were enrolled. There were 30 patients with idiopathic PAH, 10 had PAH associated with connective tissue disease, and eight with congenital heart disease. A retrospective analysis was performed to estimate the prevalence and type of supraventricular arrhythmias, as well as efficiency and safety of treatment methods. Mean follow-up period was 28.8±17.7 months. RESULTS: Supraventricular arrhythmias occurred in 17 patients (35%) and appeared to be atrial fibrillation, flutter or tachycardia. Supraventricular arrhythmias coexisted with elevated mean right atrial pressure in 75%. Four patients had more than one type of SVA. A flutter-like macro-reentrant form of atrial tachycardia dependent on cavo-tricuspid isthmus was found in four cases. The treatment of SVA included typical methods: antiarrhythmic drugs, direct current cardioversion (DCC), and radiofrequency (RF) ablation. All of the therapeutic methods were effective in managing acute arrhythmia. Three patients required re-ablation. Overall mortality: 14 patients (29%) in the whole study group, including six in SVA group (35%) and eight without SVA (26%). CONCLUSIONS: In patients with PAH DCC, pharmacological cardioversion and RF ablation can be applied safely and effectively. Flutter-like macro-reentrant atrial tachycardia dependent on cavo-tricuspid isthmus is observed in this group. It is more challenging, but possible, to successfully treat this arrhythmia with RF ablation.

Feasibility of implementation of a "simplified, No-X-Ray, no-lead apron, two-catheter approach" for ablation of supraventricular arrhythmias in children and adults.

INTRODUCTION: Although the "near-zero-X-Ray" or "No-X-Ray" catheter ablation (CA) approach has been reported for treatment of various arrhythmias, few prospective studies have strictly used "No-X-Ray," simplified 2-catheter approaches for CA in patients with supraventricular tachycardia (SVT). We assessed the feasibility of a minimally invasive, nonfluoroscopic (MINI) CA approach in such patients. METHODS: Data were obtained from a prospective multicenter CA registry of patients with regular SVTs. After femoral access, 2 catheters were used to create simple, 3D electroanatomic maps and to perform electrophysiologic studies. Medical staff did not use lead aprons after the first 10 MINI CA cases. RESULTS: A total of 188 patients (age, 45 ± 21 years; 17% <19 years; 55% women) referred for the No-X-Ray approach were included. They were compared to 714 consecutive patients referred for a simplified approach using X-rays (age, 52 ± 18 years; 7% <19 years; 55% women). There were 9 protocol exceptions that necessitated the use of X-rays. Ultimately, 179/188 patients underwent the procedure without fluoroscopy, with an acute success rate of 98%. The procedure times (63 ± 26 vs. 63 ± 29 minutes, P > 0.05), major complications (0% vs. 0%, P > 0.05) and acute (98% vs. 98%, P > 0.05) and long-term (93% vs. 94%, P > 0.05) success rates were similar in the "No-X-Ray" and control groups. CONCLUSIONS: Implementation of a strict "No-X-Ray, simplified 2-catheter" CA approach is safe and effective in majority of the patients with SVT. This modified approach for SVTs should be prospectively validated in a multicenter study.

Extraction of respiratory myogram interference from the ECG and its application to characterize sleep-related breathing disorders in atrial fibrillation.

BACKGROUND AND PURPOSE: Present methods to extract respiratory myogram interference (RMI) from the Holter-ECG and assess effect of supraventricular arrhythmias (SVAs) onto ECG-based detection of sleep-related breathing disorders (SRBDs) and AHI estimation. METHODS: RMI was quantified as residual energy after ECG cancellation or high-pass filtering for different windowing constellations. In 140 cases without (SET_A) and 10 cases with persistent SVAs (SET_B), respiratory polysomnogram annotations served as reference for SRDB detection from Holter-ECGs. We applied our previously published method to identify SRDBs in 1-min epochs and estimate the AHI based on joint modulations in RMI and QRS-area. RESULTS: Sensitivity and specificity of 0.855/0.860 in SET_A dropped to 0.831/0.75 in SET_B. A significantly higher number of wake events in SET_B likely contribute to the asymmetric decrease and is consistent with a tendency to overestimate the AHI. CONCLUSIONS: Despite reduced accuracy, RMI and QRS-area appear relatively robust against SVA and promise Holter-based detection at least of medium to severe SRBDs also in patients with SVAs.

Borg's exertion scale did not coincide with ventilatory anaerobic threshold in atrial fibrillation patients with restored sinus rhythm after ablation.

The determination of precise exercise intensity is essential for effective exercise rehabilitation. The Borg rating of perceived exertion category ratio (CR) scale is utilized to prescribe an appropriate level of exertion intensity. A Borg CR of approximately 13 coincides with the ventilatory aerobic threshold (VAT). Patients with atrial fibrillation (AF) exhibit various symptoms. We hypothesized that the workload at Borg CR13 (Borg CR13-Watt) differs from the workload at the VAT level (VAT-Watt) in AF patients with restored sinus rhythm (SR) following ablation. Accordingly, the relationship between Borg CR13-Watt and VAT-Watt was studied in patients with restored SR. Cardiopulmonary exercise testing (CPET) was performed at 101±88 days after ablation in 150 patients using a bicycle ergometer. No adverse events were observed during CPET. Borg CR13-Watt was significantly higher than VAT-Watt (67.2±27.8 Watt vs. 54.7±17.6 Watt, P<0.0001). Borg CR13-Watt showed significant linear regression with VAT-Watt (regression coefficient, 0.49, P<0.01; correlation coefficient, 0.80, P<0.01). Higher Borg CR13-Watt was associated with greater differences between Borg CR13-Watt and VAT-Watt (ΔWatt). The Bland-Altman plot showed nonconcordance between the two. Male sex, use of antiarrhythmic drugs, and smoking had contributed to the increased ΔWatt. Duration from ablation to time of CPET did not correlate with ΔWatt. Therefore, Borg CR13-Watt did not coincide with VAT-Watt in patients with restored SR. Higher Borg CR13-Watt was associated with greater ΔWatt. Prescribing exertion intensity as determined solely by perceived exertion is inadequate. CPET is required to determine the precise exercise intensity in AF patients with restored SR after ablation.

Incidence of nausea/vomiting following propofol sedation with adaptive servo-ventilation for atrial fibrillation ablation.

Background: Postoperative nausea and vomiting (PONV) following atrial fibrillation (AF) ablation can cause considerable distress. Aim: Continuous intravenous propofol sedation with adaptive servo-ventilation (ASV) with or without an analgesic, pentazocine, during AF ablation was studied in 272 consecutive patients with paroxysmal, persistent, and long-standing persistent AF. The study objectives were to determine the incidence of PONV after AF ablation and to assess the predictive value of factors for PONV using the area under the receiver operating characteristic curve (AUC). Results: The present sedation maneuver was successfully accomplished with a low incidence of hypotension and without discontinuation of ablation or switching to general anesthesia, while maintaining an acceptable procedural time (102 ± 32 min). The incidence of PONV was 5.5% (15/272). Nausea occurred in nine patients after an average of 4.6 ± 3.5 h (range: 2-12 h) postablation, and vomiting with nausea occurred in six patients after an average of 4.5 ± 3.1 h (range: 1-9 h) postablation. The postablation interval did not differ significantly between the occurrence of nausea and nausea accompanied by vomiting. AUCs based on various factors, including the Apfel score, ranged from 0.55 to 0.67, indicating low accuracy in predicting PONV occurrence. Conclusions: The incidence of PONV after propofol sedation with ASV was the lowest (5.5%) reported to date. Scoring systems, which included the Apfel score, were ineffective in predicting PONV. The low PONV incidence in addition to the efficacy of propofol sedation with ASV revealed the adequacy of this regimen for AF ablation.

The outcomes of patients with septic shock treated with propafenone compared to amiodarone for supraventricular arrhythmias are related to end-systolic left atrial volume.

AIMS: A recently published trial has shown no differences in outcomes between patients with new-onset supraventricular arrhythmia (SVA) in septic shock treated with either propafenone or amiodarone. However, these outcome data have not been evaluated in relation to the presence or absence of a dilated left atrium (LA). METHODS AND RESULTS: Patients with SVA and a left ventricular ejection fraction ≥ 35% were randomized to receive intravenous propafenone (70 mg bolus followed by 400-840 mg/24 h) or amiodarone (300 mg bolus followed by 600-1800 mg/24 h). They were divided into groups based on whether their end-systolic left atrial volume (LAVI) was ≥40 mL/m². The subgroup outcomes assessed were survival at ICU discharge, 1 month, 3 months, 6 months, and 12 months. Propafenone cardioverted earlier (P = 0.009) and with fewer recurrences (P = 0.001) in the patients without LA enlargement (n = 133). Patients with LAVI < 40 mL/m2 demonstrated a mortality benefit of propafenone over the follow-up of 1 year [Cox regression, hazard ratio (HR) 0.6 (95% CI 0.4; 0.9), P = 0.014]. Patients with dilated LA (n = 37) achieved rhythm control earlier in amiodarone (P = 0.05) with similar rates of recurrences (P = 0.5) compared to propafenone. The outcomes for patients with LAVI ≥ 40 mL/m2 were less favourable with propafenone compared to amiodarone at 1 month [HR 3.6 (95% CI 1.03; 12.5), P = 0.045]; however, it did not reach statistical significance at 1 year [HR 1.9 (95% CI 0.8; 4.4), P = 0.138]. CONCLUSION: Patients with non-dilated LA who achieved rhythm control with propafenone in the setting of septic shock had better short-term and long-term outcomes than those treated with amiodarone, which seemed to be more effective in patients with LAVI ≥ 40 mL/m². TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03029169, registered on 24 January 2017.

Risk Factors for Atrial Fibrillation in the Dog: A Systematic Review.

Different risk factors for atrial fibrillation (AF) development have been identified in numerous studies on humans, but this information is less clearly available on the dog. The aim of this systematic review is to determine the risk factors for AF in the dog. Following the PRISMA 2020 guidelines, we conducted a comprehensive search using the Web of Science and Scopus databases for articles reporting on cases of spontaneously occurring AF in dogs. The level of evidence was assessed using the Evidence Quality Grading System of the National Institute of Health. One thousand forty-three studies were initially identified, and twenty of them were included in this systematic review involving 2,359,275 dogs, of which 4807 showed spontaneously occurring AF. Genetics, for the Irish Wolfhound, increased body weight, and left atrial enlargement were the main risk factors for the development of AF in dogs with different cardiac diseases, particularly myxomatous mitral valve disease (MMVD) and dilated cardiomyopathy (DCM). However, some differences were found between these two cardiac diseases regarding additional risk factors. In particular, the presence of congestive heart failure and echocardiographic evidence of increased left atrial pressure or the presence of right atrial enlargement emerged as risk factors in dogs with MMVD or DCM, respectively. Furthermore, significant differences in risk factors were observed between dogs and humans. In particular, advanced age and male sex are not reliable indicators of an increased risk of AF in dogs.

Current knowledge for the risk factors of early permanent pacemaker implantation following transcatheter aortic valve replacement and what is next for the primary prevention?

In this editorial, we comprehensively summarized the preoperative risk factors of early permanent pacemaker implantation after transcatheter aortic valve replacement (TAVR) among patients with severe aortic stenosis from several renowned clinical studies and focused on the primary prevention of managing the modifiable factors, e.g., paroxysmal atrial fibrillation before the TAVR.

Magnetic navigation in adults with atrial isomerism (heterotaxy syndrome) and supraventricular arrhythmias.

AIMS: We analysed the type and mechanism of supraventricular arrhythmias encountered in a series of symptomatic adults with atrial isomerism undergoing catheter ablation procedures. METHODS AND RESULTS: The study population included consecutive adults with atrial isomerism who had previously undergone surgical repair or palliation of the associated anomalies. Patients underwent electrophysiological study for symptomatic arrhythmia in our institution between 2010 and 2012 using magnetic navigation in conjunction with CARTO RMT and three-dimensional (3D) image integration. Eight patients (five females) with a median age of 33 years [interquartile range (IQR) 24-39] were studied. Access to the cardiac chambers of interest was obtained retrogradely via the aorta using remotely navigated magnetic catheters in six patients. Radiofrequency ablation successfully targeted twin atrioventricular (AV) nodal reentrant tachycardia in two patients, atrial fibrillation (AF) in three, focal atrial tachycardia (AT) mainly originating in the left-sided atrium in four patients, and macro-reentrant AT dependent on a right-sided inferior isthmus in three patients. The median fluoroscopy time was 3.0 min (IQR 2-11). After a median follow-up of 10 months (IQR 6-21), five of the ablated patients are free from arrhythmia; two patients experienced episodes of self-terminated AF and AT, respectively, within one month post-ablation; the remaining patient had only non-sustained AT during the electrophysiological study and was managed medically. CONCLUSION: Various supraventricular tachycardia mechanisms are possible in adults with heterotaxy syndrome, all potentially amenable to radiofrequency ablation. The use of remote magnetic navigation along with 3D mapping facilitated the procedures and resulted in a short radiation time.

Dual Atrioventricular Nodal Non-Re-Entrant Tachycardia.

A patient presented with symptoms of palpitations. Her standard 12-lead electrocardiogram captured 3 potential causes of her symptoms (premature atrial contractions, junctional rhythm, and narrow complex tachycardia). Further workup uncovered dual atrioventricular node physiology with 1:2 sinus conduction and resultant alternating QRS from a slow and fast conduction pathway. (Level of Difficulty: Intermediate.).

Coronary sinus ablations in pediatric patients with supraventricular arrhythmias.

BACKGROUND: Intracoronary sinus ablations have been performed for various arrhythmical substrates. The aim of this study is to report our experience on pediatric patients of the safety and efficacy of ablations in the coronary sinus. METHODS: This is a retrospective study of all patients who underwent ablations in the coronary sinus from October 2013 to October 2021 at a single center. Clinical presentation, type of arrhythmia causing tachycardia, ablation procedure, and outcome were recorded. RESULTS: A total of 27 patients were included in the study. Nineteen (69%) of those followed up received a diagnosis of Wolff-Parkinson-White syndrome (WPW), 4 (15%) were cases of supraventricular tachycardia with concealed accessory pathway (AP), 2 (8%) were cases of focal atrial tachycardia, and 2 (8%) were cases of permanent junctional reciprocating tachycardia. Negative delta wave was noteworthy especially in lead II in 11/19 (58%) cases and coronary sinus diverticulum was detected in the WPW cases. Of those with manifest AP (19 cases), 15 (79%) had a high-risk AP and the AP in all WPW cases was adenosine unresponsive. Radiofrequency (RF) catheter ablation was performed in 25/27 (93%) cases during the procedure, and 16/25 (64%) of these were irrigated RF catheters. No complications were observed in the follow-up, including coronary artery injury. CONCLUSIONS: Catheter ablation of supraventricular tachyarrhythmias can be accomplished effectively and potentially safely within the coronary sinus. Coronary sinus diverticula should be suspected in patients with manifest posteroseptal APs who have a previous failed ablation and typical electrocardiographic signs.