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Fetal autoimmune atrioventricular block (AVB) is a rare but potentially lifethreatening condition. It results from the passage of maternal anti-SSA/Ro or Anti SSB/La auto-antibodies into the fetal circulation, leading to inflammation and fibrosis of the AV node and often to irreversible damage. Besides AVB, these antibodies can also cause cardiomyopathies, but there is no evidence linking them to tachyarrhythmias. We present the case of a patient with significant risk factors for fetal AVB: a prior history of hydrops fetalis, high anti-SSA/Ro antibody levels and hypothyroidism. In this case, the use of dexamethasone and intravenous immunoglobulin may have contributed to reversing the first degree atrioventricular block detected at 19 weeks of gestation. Additionally, at 21 weeks, the fetus developed a tachyarrhythmia that needed treatment with flecainide. Soon after the birth, the newborn underwent ECG Holter and Wolff-Parkinson-White Syndrome (WPWS) was diagnosed. To our knowledge, the coexistence of fetal AVB and WPWS has never been described. [ABSTRACT FROM AUTHOR]

Background: Atrioventricular node (AVN) ablation is an effective treatment for atrial fibrillation (AF) with uncontrolled ventricular rates despite maximal pharmacological treatment. Intracardiac echocardiography (ICE) can help with visualizing structures, positioning catheters, and guiding the ablation procedure. We compared only fluoroscopy-guided and ICE-guided AVN ablation regarding patients with permanent AF. Methods: Sixty-two consecutive patients underwent AVN ablation were enrolled in our retrospective single-center study (ICE group: 28 patients, Standard group: 34 patients). Procedural data, acute and long-term success rate, and complications were analyzed. Results: ICE guidance for AVN ablation significantly reduced fluoroscopy time (0.30 [0.06; 0.85] min vs. 7.95 [3.23; 6.59] min, p < 0.01), first-to-last ablation time (4 [2; 16.3] min vs. 26.5 [2.3; 72.5] min, p = 0.02), and in-procedure time (40 [34; 55] min vs. 60 [45; 110], p = 0.02). There was no difference in either the total ablation time (199 [91; 436] s vs. 294 [110; 659] s, p = 0.22) or in total ablation energy (8272 [4004; 14,651] J vs. 6065 [2708; 16,406] J, p = 0.28). The acute success rate was similar (ICE: 100% vs. Standard: 94%, p = 0.49) between the groups. Conclusions: In our retrospective trial, ICE-guided AVN ablation reduced fluoroscopy time, procedure time, and first-to-last ablation time. There was no difference in ablation time, total ablation energy, acute and long-term success, and complication rate. [ABSTRACT FROM AUTHOR]

The article presents a case study of a patient with ventricular tachycardia originating from the para-Hisian region, where detailed electrophysiological mapping and pacing maneuvers were used to identify the reentrant mechanism. It also discusses the effectiveness of entrainment pacing in determining the optimal ablation site, challenges associated with ablation in this anatomical region, and the role of detailed electroanatomical mapping in avoiding damage to the AV conduction system.

Objective: The management of women presenting with with complete heart block during pregnancy remains very challenging.Untill now, there is not an established consensus for the most appropriate anaesthetic technique for caesarean section in women with complete atrioventricular block. Case(s): On our case, the atrioventricular complete heart block was diagnosed on the preoperative routine test for Caesarian Section due to cephalo-pelvic disproportion. The patient had no regular antenatal check ups at a local hospital. Her parents reported rare episodes of syncope during childhood and adolescence and one more episode two year before. During pregnancy she did not report any sincope episode except from being tired . For obstetric reasons caesarean section was performed successfully under spinal anaesthesia with continuous monitorization during intraoperative time without a pacemaker .Even though the patient reacted well during administration of atropine a temporary pacemaker was found to be in case we would need it. A healthy baby boy of 3350 gram was delivered. During postpartum period the patient did not have any complains or syncope episodes. It was strongly recommended to her a regular follow up to cardiology department. Conclusion: As suggested by our case, asymptomatic atrioventricular complete heart block in pregnancy can be managed successfully without pacemaker. However, careful monitoring, is necessity by the pregnancy heart team with a cardiologist, anaesthetist and obstetrician, with experience in the management of high risk pregnancies. Management of the risk for cardiovascular and obstetrical complications is difficult in pregnant women with complete heart block. Asymptomatic complete heart block in late pregnancy should be managed without pacemaker by the pregnancy heart team with a cardiologist, anaesthetist and obstetrician, with experience in the management of high risk pregnancies. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Venous spasm is an important reason for complicated or failed implantations of cardiac implantable electronic devices. Prevention or risk reduction of venous spasm during cardiac implantable electronic device implantation may be achieved by ultrasound or fluoroscopic imaging prior to puncture, cephalic vein cut‐down, sufficient pre‐ and perioperative hydration, nitroglycerin injection and effective sedation, and analgesia. This case report with literature review focuses on venous spasm as a potential cause for complicated implantations of cardiac implantable electronic devices. The case report is clinically relevant as it describes a progressive spasm affecting the axillary and the subclavian vein. A 66‐year‐old female complained of symptomatic atrial fibrillation (AF) and atypical atrial flutter despite interventional and medical treatment. As an ultimate treatment, she was scheduled for pacemaker implantation and atrioventricular node ablation. Several puncture attempts of the axillary vein failed. Despite venous blood aspiration, no guidewires could be advanced into the axillary vein. We performed a first venogram revealing significant spasm of the axillary vein. Another failed venous puncture occurred after change of access site to the subclavian vein. A second venogram displayed progression of the spasm, now affecting both the axillary and the subclavian veins. Normal saline perfusion was administered as well as intravenous isosorbide. Unfortunately, a repeated venogram after 15 min waiting time showed persistence of the spasm, still affecting both veins. The procedure was discontinued as the patient became uncomfortable. Venous spasm is an important reason for complicated or failed implantations of cardiac implantable electronic devices. Commonly used medical prevention and treatment are intravenous fluids and nitroglycerin. Prevention or risk reduction of venous spasm during cardiac implantable electronic device implantation may be achieved by ultrasound or fluoroscopic imaging prior to puncture, cephalic vein cut‐down, sufficient pre‐ and perioperative hydration, nitroglycerin injection and effective sedation and analgesia. [ABSTRACT FROM AUTHOR]

Background: There is limited research on the intra‐individual efficacy of ventricular pacing minimization algorithms developed by Biotronik—the Ventricular Pace Suppression algorithm (VpS) and the Intrinsic Rhythm Support plus algorithm (IRSplus) (BIOTRONIK SE & Co. KG, Berlin, Germany). We performed a randomized pilot trial that evaluated the efficacy of two algorithms in patients with symptomatic sinus node dysfunction (SND) who received a dual‐chamber pacemaker. Methods: The trial was conducted in 11 tertiary hospitals in South Korea. The patients were randomized to either the VpS or IRSplus algorithm group after a 3‐month period of fixed atrioventricular (AV) delay. The primary outcome was the ventricular pacing percentage (Vp%) at each follow‐up visit. The secondary outcomes were the occurrence of heart failure (HF) and atrial fibrillation (AF) during the study period. Results: Data from 131 patients were analyzed. Initially, their average Vp% over 3 months with a fixed AV interval was 14.1 ± 19.4%. Patients were randomly assigned to VpS and IRSplus groups, with 66 and 65 in each. Algorithms reduced average Vp% to 4.0 ± 11.3% at 9 months and 6.7 ± 14.9% at 15 months. These algorithms were more effective for patients with paced AV delay (PAVD) ≤300 ms compared to those with PAVD >300 ms. Both algorithms were equally effective in reducing Vp%. Clinical AF or HF hospitalization was not observed during the study period. Conclusion: The VpS and IRSplus algorithms are effective and safe in minimizing unnecessary ventricular pacing in patients with SND. [ABSTRACT FROM AUTHOR]

In the field of cardiac electrophysiology, there is a universal desire: the discovery of a flawless diagnostic maneuver for supraventricular tachycardias (SVTs). This is not merely a wish but a shared odyssey. To improve diagnostic accuracy and achieve sufficient sensitivity and specificity, numerous diagnostic maneuvers have been proposed. However, each has its limitations and prompts a search for new diagnostic techniques. This continuous cycle of discovery and refinement, which we titled "SVT Quest" is reviewed in chronological sequence. This adventure in diagnosing narrow QRS tachycardia unfolds in 3 steps: Step 1 involves differentiating atrial tachycardia from other SVTs based on the observations such as V‐A‐V or V‐A‐A‐V response, ΔAA interval, VA linking, the last entrainment sequence, and response to the atrial extrastimulus. Step 2 focuses on differentiating orthodromic reciprocating tachycardia from atrioventricular nodal reentrant tachycardia based on the observations such as tachycardia reset upon the premature ventricular contraction during His refractoriness, uncorrected/corrected postpacing interval, differential ventricular entrainment, orthodromic His capture, transition zone analysis, and total pacing prematurity. Step 3 characterizes the concealed nodoventricular/nodofascicular pathway and His‐ventricular pathway‐related tachycardia based on observations such as V‐V‐A response, ΔatrioHis interval, and paradoxical reset phenomenon. There is no single diagnostic maneuver that fits all scenarios. Therefore, the ability to apply multiple maneuvers in a case allows the operator to accumulate evidence to make a likely diagnosis. Let's embark on this adventure! [ABSTRACT FROM AUTHOR]

The cardiac conduction system (CCS) is a network of specialized cardiomyocytes that coordinates electrical impulse generation and propagation for synchronized heart contractions. Although the components of the CCS, including the sinoatrial node, atrioventricular node, His bundle, bundle branches, and Purkinje fibers, were anatomically discovered more than 100 years ago, their molecular constituents and regulatory mechanisms remain incompletely understood. Here, we demonstrate the transcriptomic landscape of the postnatal mouse CCS at a single-cell resolution with spatial information. Integration of single-cell and spatial transcriptomics uncover region-specific markers and zonation patterns of expression. Network inference shows heterogeneous gene regulatory networks across the CCS. Notably, region-specific gene regulation is recapitulated in vitro using neonatal mouse atrial and ventricular myocytes overexpressing CCS-specific transcription factors, Tbx3 and/or Irx3. This finding is supported by ATAC-seq of different CCS regions, Tbx3 ChIP-seq, and Irx motifs. Overall, this study provides comprehensive molecular profiles of the postnatal CCS and elucidates gene regulatory mechanisms contributing to its heterogeneity. The cardiac conduction system consists of specialized cardiomyocytes that synchronize heart contractions. Here, Oh et al. provide comprehensive molecular profiles of the postnatal cardiac conduction system and elucidate gene regulatory mechanisms contributing to its heterogeneity. [ABSTRACT FROM AUTHOR]

Background: Dexmedetomidine and propofol are common sedatives in intensive care units and for interventional procedures. Both may compromise sinus node function and atrioventricular conduction. The objective of this prospective, randomized study is to compare the effect of dexmedetomidine with propofol on sinus node function and atrioventricular conduction. Methods: In a tertiary care center in Switzerland we included from September 2019 to October 2020 160 patients (65 ± 11 years old; 32% female) undergoing first ablation for atrial fibrillation by cryoballoon ablation or by radiofrequency ablation. Patients were randomly assigned to deep sedation with dexmedetomidine (DEX group) versus propofol (PRO group). A standard electrophysiological study was performed after pulmonary vein isolation with the patients still deeply sedated and hemodynamically stable. Results: Eighty patients each were randomized to the DEX and PRO group. DEX group patients had higher baseline sinus cycle length (1022 vs. 1138 ms; p = 0.003) and longer sinus node recovery time (SNRT400; 1597 vs. 1412 ms; p = 0.042). However, both corrected SNRT and normalized SNRT did not differ. DEX group patients had longer PR interval (207 vs. 186 ms; p = 0.002) and AH interval (111 vs. 95 ms, p = 0.008), longer Wenckebach cycle length of the atrioventricular node (512 vs. 456 ms; p = 0.005), and longer atrioventricular node effective refractory period (390 vs. 344 ms; p = 0.009). QRS width and HV interval were not different. An arrhythmia, mainly atrial fibrillation, was induced in 33 patients during the electrophysiological study, without differences among groups (20% vs. 15%, p = 0.533). Conclusions: Dexmedetomidine has a more pronounced slowing effect on sinus rate and suprahissian AV conduction than propofol, but not on infrahissian AV conduction and ventricular repolarization. These differences need to be taken into account when using these sedatives. Trial registration: ClinicalTrials.gov number NCT03844841, 19/02/2019 [ABSTRACT FROM AUTHOR]

This article discusses a case of narrow complex tachycardia with alternating atrial activation. The patient had previously undergone an ablation procedure for pre-excited atrial fibrillation but experienced recurrent episodes of palpitations. The article explores the mechanism behind the alternating atrial activation and suggests that it may be due to conduction block across the mitral isthmus. The left lateral pathway was successfully ablated, resulting in the resolution of the tachycardia. Further research and mapping techniques are recommended to improve the accuracy of ablation procedures. [Extracted from the article]

The article presents a case study of a 21-year-old woman undergoing electrophysiological study for long RP (Refractory Period) tachycardia. It initially suspected atrial tachycardia or atypical atrioventricular nodal reentrant tachycardia (aAVNRT), later confirming slow-slow AVNRT. It is reported that Radiofrequency ablation targeted the AV (atrioventricular) node's right inferior extension, successfully resolving the tachycardia.

The article presents a case study of a 69-year-old female who underwent an electrophysiological study due to recurrent supraventricular tachycardia (SVT). It highlighted the occurrence of a wide complex tachycardia (WCT) and explored the mechanism behind its transformation following a premature ventricular complex (PVC). Treatment discussed involved radiofrequency ablation targeting the base of the triangle of Koch, which successfully eliminated SVT inducibility and potentially the NFV pathway.

Background: Severe first‐degree atrioventricular (AV) block may produce symptoms similar to heart failure due to AV dyssynchrony, a syndrome termed AV dromotropathy. According to guidelines, it should be considered for permanent pacemaker implantation, yet evidence supporting this treatment is scarce. Objectives: This study aimed to determine the impact of AV‐optimized conduction system pacing (CSP) in patients with symptomatic severe first‐degree AV block and echocardiographic signs of AV dyssynchrony. Methods: Patients with symptomatic first‐degree AV block (PR > 250 ms), preserved left ventricular ejection fraction, narrow QRS, and AV dyssynchrony were included in the study. In a single‐blind cross‐over design, patients were randomized to AV sequential CSP or backup VVI pacing with a base rate of 40 bpm. We compared exercise capacity, echocardiographic parameters, and symptom occurrence at the end of 3 months of each period. Results: Fourteen patients completed the study. During the AV‐optimized CSP compared to the backup pacing period, patients achieved a higher workload on exercise test (147.2 ± 50.9 vs. 140.7 ± 55.8 W; p =.032), with a trend towards higher peak VO2 (23.3 ± 7.1 vs. 22.8 ± 7.1 mL/min/kg; p =.224), and higher left ventricular stroke volume (LVSV 74.5 ± 13.8 vs. 66.4 ± 12.5 mL; p <.001). Symptomatic improvement was recorded, with fewer patients reporting general tiredness and 71% of patients preferring the AV‐optimized CSP (p =.008). Conclusions: AV‐optimized CSP could improve symptoms, exercise capacity and LVSV in patients with severe first‐degree AV block. [ABSTRACT FROM AUTHOR]

Introduction: Concomitant left bundle branch area pacing (LBBAP) with atrioventricular (AV) nodal ablation is emerging as a viable management option in atrial fibrillation refractory to medical management. Its viability in patients with pulmonary disease and atrial fibrillation is unknown. Methods and results: This is a retrospective, observational cohort study in consecutive patients who underwent concomitant LBBAP with AV nodal ablation with advanced pulmonary disease at the Cleveland Clinic Fairview Hospital between January 2019 and January 2023. Patient characteristics, comorbidities, and medication use were extracted via chart review. Rates of hospitalizations, medication use, and structural disease seen on echocardiography were compared before and after the procedure. There were 27 patients with group 3 pulmonary hypertension who underwent the procedure. In the 24 months preprocedure, there were 114 admissions for heart failure or atrial fibrillation compared to 9 admissions postprocedure (p <.001). Mean follow up was 17.3 ± 12.1 months. There were no significant complications or lead dislodgements. Echocardiographic characteristics were similar prior to and after pacemaker implantation. Use of medications for rate and rhythm control was common preprocedure, and was reduced dramatically postprocedure. Conclusion: This small, retrospective cohort study suggests concomitant LBBAP with AV nodal ablation may be safe and efficacious for management of atrial fibrillation in patients with advanced pulmonary disease. [ABSTRACT FROM AUTHOR]

This article, titled "PVC or Not PVC? That Is the Question," discusses a case study of a 32-year-old man who was referred for evaluation of potential premature ventricular contraction (PVC)-induced cardiomyopathy. The patient had a sinus rhythm with numerous wide QRS complex ectopic beats and severe left ventricular dysfunction. The article explores the correct diagnosis based on the electrocardiogram (ECG) results and discusses the treatment and outcome of the patient. It also highlights the importance of careful examination of QRS morphology to differentiate between supraventricular beats with aberrancy and ventricular beats. [Extracted from the article]

Background: The lead of left bundle branch area pacing (LBBAP) inserted into the muscular septum will make the transvenous lead extraction (TLE) of LBBAP more challenging and because in LBBAP ventricular lead (V lead) should be inserted into the part of the septum, damage to the vessel near the lead could occur. The case reports introduced the complications of LBBAP previously introduced, but not being considered in detail. Case presentation: The two patients (76-year-old man, 90-year-old man) with a complete atrioventricular block (CAVB) undergoing the LBBAP procedure experienced complications related to the procedure. The complications were abrupt dysfunction of V lead and damage to the septal vein in the process of the procedure, respectively. Fortunately, they were discharged without any other complications. Conclusions: A deliberate approach for the procedure would be needed as well as successful insertion appropriate for the protocol of LBBAP. And long-term follow-up of complications should be needed. [ABSTRACT FROM AUTHOR]

The feasibility of the conduction system pacing combined with atrioventricular node ablation was demonstrated in patients with atrial fibrillation in whom rate control can't be achieved with medication and heart failure. We present a case of an 82-year-old man with a personal history of permanent atrial fibrillation, admitted with symptoms of heart failure. The resting electrocardiogram showed a very fast ventricular response, and the echocardiography showed a depressed left ventricular function, raising the suspicion of a tachycardia-mediated cardiomyopathy. Since the patient was on maximum doses of atrioventricular nodal-blocking drugs, we opted for a physiological pacing and atrioventricular node ablation strategy. First, the His bundle capture was achieved at low pacing thresholds, and ablation of the atrioventricular node was attempted. Unfortunately, after several failed attempts, an acute increase in the His bundle capture threshold was noted, suggesting inadvertent tissue ablation beneath the pacing lead. In this scenario, we removed the lead from the His bundle area and achieved optimal left bundle branch area pacing. With the lead in this position, atrioventricular node ablation was performed during the first attempt. At the six-month follow-up, there was no recovery of atrioventricular node conduction. Device interrogation revealed stable pacing and sensing parameters, and there was a significant improvement in clinical status and left ventricular function. Mastering both His bundle pacing and left bundle branch area pacing offers the potential to overcome intraprocedural challenges, giving alternative strategies to achieve physiological pacing. These approaches can be used interchangeably based on the evolving dynamics of the procedure and the patient's specific needs. [ABSTRACT FROM AUTHOR]

Significance: Damage to the cardiac conduction system remains one of the most significant risks associated with surgical interventions to correct congenital heart disease. This work demonstrates how light-scattering spectroscopy (LSS) can be used to non-destructively characterize cardiac tissue regions. Aim: To present an approach for associating tissue composition information with location-specific LSS data and further evaluate an LSS and machine learning system as a method for non-destructive tissue characterization. Approach: A custom LSS probe was used to gather spectral data from locations across 14 excised human pediatric nodal tissue samples (8 sinus nodes, 6 atrioventricular nodes). The LSS spectra were used to train linear and neural-network-based regressor models to predict tissue composition characteristics derived from the 3D models. Results: Nodal tissue region nuclear densities were reported. A linear model trained to regress nuclear density from spectra achieved a prediction r-squared of 0.64 and a concordance correlation coefficient of 0.78. Conclusions: These methods build on previous studies suggesting that LSS measurements combined with machine learning signal processing can provide clinically relevant cardiac tissue composition. [ABSTRACT FROM AUTHOR]

Introduction: Postoperative atrial fibrillation (POAF) is common following open heart surgery, and is associated with significant morbidity. Medications used for ventricular rate control of POAF may not be effective in controlling rapid ventricular rates during the postoperative period because of increased sympathetic tone. The purpose of this study was to develop nonpharmacologic rate control of POAF by atrioventricular node (AVN) fat pad stimulation using clinically available temporary pacing wires in the canine sterile pericarditis model. Methods: We studied 10 sterile pericarditis dogs in the closed‐chest state on postoperative days 1−3. The AVN fat pad stimulation (amplitude 2–15 mA; frequency 20 Hz; pulse width 0.03–0.2 ms) was performed during sustained POAF (>5 min). We measured ventricular rate and inefficient ventricular contractions during sustained POAF and compared it with and without AVN fat pad stimulation. Also, the parameters of AVN fat pad stimulation to achieve a rate control of POAF were measured over the postoperative days. Results: Eleven episodes of sustained POAF were induced in 5/10 sterile pericarditis dogs in the closed‐chest state on postoperative days 1−2. During POAF, the AVN fat pad stimulation decreased the ventricular rate from 178 ± 52 bpm to 100 ± 8 bpm in nine episodes. Nonpharmacologic rate control therapy successfully controlled the ventricular rate and eliminated inefficient ventricular contractions during POAF for the duration of the AVN fat pad stimulation. The AVN fat pad stimulation output remained relatively stable over the postoperative days. Conclusion: During sustained POAF, nonpharmacologic rate control by AVN fat pad stimulation effectively and safely controlled rapid ventricular rates throughout the postoperative period. [ABSTRACT FROM AUTHOR]

The article focuses on exploring the mechanism behind narrow QRS tachycardia recurrence in a patient years after undergoing "rightward inferior extension" ablation for atrioventricular nodal reentrant tachycardia (AVNRT). Topics include the identification of the tachycardia's origin near the His bundle, unsuccessful ventricular entrainment pacing, and the diagnostic challenges posed by variations in atrio-His intervals during electrophysiological study and ablation procedures.

Background: Patients who have recurrent atrial fibrillation (AF) following redo catheter ablation may eventually be managed with a pace-and-ablate approach, involving pacemaker implant followed by atrioventricular nodal ablation (AVNA). We sought to determine which factors would predict subsequent AVNA in patients undergoing redo AF ablation. Methods: We analyzed patients undergoing redo AF ablations between 2013 and 2019 at our institution. Follow-up was censored on December 31, 2021. Patients with no available follow- up data were excluded. Time-to-event analysis with Cox proportional hazard regression was used to compare those who underwent AVNA to those who did not. Results: A total of 467 patients were included, of whom 39 (8.4%) underwent AVNA. After multivariable adjustment, female sex (aHR 4.68 [95% CI 2.30-9.50]; p < 0.001), ischemic heart disease (aHR 2.99 [95% CI 1.25-7.16]; p = 0.014), presence of a preexisting pacemaker (aHR 3.25 [95% CI 1.10-9.60]; p = 0.033), and persistent AF (aHR 2.22 [95% CI 1.07-4.59]; p = 0.032) were associated with increased risk of subsequent AVNA requirement. Conclusion: Female sex, ischemic heart disease, and persistent AF may be useful clinical predictors of the requirement for subsequent AVNA and may be considered as part of shared clinical decision making. [ABSTRACT FROM AUTHOR]

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) sometimes recurs even after anatomical slow pathway (SP) ablation targeting the rightward inferior extension (RIE). This multicenter study aimed to determine the reasons for AVNRT recurrence. Methods and Results: Forty-six patients were treated successfully for recurrent AVNRT. Initial treatment was for 38 slow-fast AVNRTs, 3 fast-slow AVNRTs, 2 slow-slow AVNRTs, 2 slow-fast and fast-slow AVNRTs, and 1 noninducible AVNRT. All initial treatments were of RF application to the RIE; SP elimination was achieved in 11, dual AVN physiology was seen in 29, and AVNRT remained inducible in 5. The recurrent AVNRTs included 34 slow-fast AVNRTs, 6 fast-slow AVNRTs, 3 slow-slow AVNRTs, 2 slow-fast and fast-slow AVNRTs, and 1 slow-fast and slow-slow AVNRTs. Successful ablation site was within the RIE in 39 and left inferior extension in 7. In 30 of 39, the successful RIE site was in the same area or higher than that of the initial procedure. Conclusion: For a high majority (around 85%) of patients in whom AVNRT recurs after initial ablation success, the site of a second successful procedure will be within the RIE even though the RIE was originally targeted. Furthermore, a high majority (around 86%) of sites of successful ablation will be higher than those originally targeted. [ABSTRACT FROM AUTHOR]

Background Double-wave macrore-entry is a rare mechanism of atrial tachycardia with limited documentation in the literature. We present a three-dimensional documentation of a double-wave 'typical' atrial flutter in a patient with extensive atrial cardiomyopathy. Case summary A 78-year-old female with a history of atrial cardiomyopathy and dual-chamber pacemaker for sinus node disease presented with palpitations and incessant atrial flutter. Electrophysiological study revealed a regular tachycardia with a cycle length (TCL) of 230 ms, with proximal to distal coronary sinus (CS) activation. Three-dimensional mapping identified two independent wavefronts circulating the cavotricuspid isthmus (CTI), each with a TCL of 460 ms. Cavotricuspid isthmus ablation resulted in conversion into a distinct tachycardia with left atrial roof origin. Linear ablation in this location slowed the TCL to 435 ms with concentric CS activation and another CTI dependent atrial flutter was mapped, this time with only one wavefront of activation. Further ablation with a second, more lateral, line in the CTI led to tachycardia interruption. Given the extensive atrial scarring and high arrhythmic recurrence risk, atrioventricular node ablation was performed. Discussion Double-wave re-entrant tachycardias were primarily observed in experimental models, precipitating acceleration of ventricular and supraventricular tachycardias via extrastimulation. In our case, there is documentation of a spontaneous double-wave of activation around the CTI, representing the first documented double-wave 'typical' atrial flutter. Unlike other cases in the literature, the two wavefronts were equidistant, which resulted in a regular tachycardia with TCL that was half of the single-wave cycle length. Three-dimensional propagation mapping was essential to visualize the two distinct wavefronts. [ABSTRACT FROM AUTHOR]

Assess pre and postinterventional anxiety levels in radiofrequency catheter ablation recipients (RFCA) for atrioventricular nodal reentry tachycardia (AVNRT) and investigate whether changes are associated with demographic and clinical characteristics and AVNRT subtypes. This was a single-centre prospective study conducted from September 2019 to March 2020. A total of 51 patients who were to undergo RFCA due to newly diagnosed symptomatic AVNRT were included. Electrophysiological studies were performed on all patients, the AVNRT subtype was determined, and the RFCA procedure was applied. The severity of anxiety before RFCA and 3 months after the procedure was determined by the state-trait anxiety inventory. The mean age was 50.1±17.3 years and 70.6% (n=36) were women. The median STAI-State score after ablation (37 [33–42]) was significantly lower than before (63 [52–72]) (p<0.001). Similarly, median STAI-Trait scores after ablation (45 [39–49]) were found to be significantly lower than before the procedure (59 [46–69]) (p<0.001). There were no significant relationships between the decrease in STAI-State or STAI-Trait scores and analyzed parameters such as age, sex, AVNRT type and other laboratory values. Administration of RFCA in AVNRT can improve AVNRT-induced anxiety and could eliminate the potential need for antiarrhythmic or anxiolytic therapy. Therefore, RFCA may also positively impact quality of life, and reduce unnecessary treatments, and healthcare costs associated with AVNRT. [ABSTRACT FROM AUTHOR]

Tricuspid valve disease is an often underrecognized clinical problem that is associated with significant morbidity and mortality. Unfortunately, patients will often present late in their disease course with severe right-sided heart failure, pulmonary hypertension, and life-limiting symptoms that have few durable treatment options. Traditionally, the only treatment for tricuspid valve disease has been medical therapy or surgery; however, there have been increasing interest and success with the use of transcatheter tricuspid valve therapies over the past several years to treat patients with previously limited therapeutic options. The tricuspid valve is complex anatomically, lying adjacent to important anatomic structures such as the right coronary artery and the atrioventricular node, and is the passageway for permanent pacemaker leads into the right ventricle. In addition, the mechanism of tricuspid pathology varies widely between patients, which can be due to primary, secondary, or a combination of causes, meaning that it is not possible for 1 type of device to be suitable for treatment of all cases of tricuspid valve disease. To best visualize the pathology, several modalities of advanced cardiac imaging are often required, including transthoracic echocardiography, transesophageal echocardiography, cardiac computed tomography, and cardiac magnetic resonance imaging, to best visualize the pathology. This detailed imaging provides important information for choosing the ideal transcatheter treatment options for patients with tricuspid valve disease, taking into account the need for the lifetime management of the patient. This review highlights the important background, anatomic considerations, therapeutic options, and future directions with regard to treatment of tricuspid valve disease. [ABSTRACT FROM AUTHOR]

Introduction: Information about autonomic nervous system (ANS) activity may offer insights about atrial fibrillation (AF) progression and support personalized AF treatment but is not easily accessible from the ECG. In this study, we propose a new approach for ECG-based assessment of respiratory modulation in atrioventricular (AV) nodal refractory period and conduction delay. Methods: A 1-dimensional convolutional neural network (1D-CNN) was trained to estimate respiratory modulation of AV nodal conduction properties from 1- minute segments of RR series, respiration signals, and atrial fibrillatory rates (AFR) using synthetic data that replicates clinical ECG-derived data. The synthetic data were generated using a network model of the AV node and 4 million unique model parameter sets. The 1D-CNN was then used to analyze respiratory modulation in clinical deep breathing test data of 28 patients in AF, where an ECG-derived respiration signal was extracted using a novel approach based on periodic component analysis. Results: We demonstrated using synthetic data that the 1D-CNN can estimate the respiratory modulation from RR series alone with a Pearson sample correlation of r = 0.805 and that the addition of either respiration signal (r = 0.830), AFR (r = 0.837), or both (r = 0.855) improves the estimation. Discussion: Initial results from analysis of ECG data suggest that our proposed estimate of respiration-induced autonomic modulation, aresp, is reproducible and sufficiently sensitive to monitor changes and detect individual differences. However, further studies are needed to verify the reproducibility, sensitivity, and clinical significance of aresp. [ABSTRACT FROM AUTHOR]

A 16-year-old man presented with short VA supraventricular tachycardia and 2:1 atrioventricular ratio. The correct maneuvers allowed us to guide not only the mechanism but also the probable location of the atrioventricular block. [ABSTRACT FROM AUTHOR]

Introduction: Mapping system is useful in ablation of atrioventricular nodal reentry tachycardia (AVNRT) and localization of anatomic variances. Voltage mapping identifies a low voltage area in the Koch triangle called low‐voltage‐bridge (LVB); propagation mapping identifies the collision point (CP) of atrial wavefront convergence. We conducted a prospective study to evaluate the relationship between LVB and CP with successful site of ablation and identify standard value for LVB. Materials and Methods: Three‐dimensional (3D) maps of the right atria were constructed from intracardiac recordings using the ablation catheter. Cut‐off values on voltage map were adjusted until LVB was observed. On propagation map, atrial wavefronts during sinus rhythm collide in the site representing CP, indicating the area of slow pathway conduction. Ablation site was selected targeting LVB and CP site, confirmed by anatomic position on fluoroscopy and atrioventricular ratio. Results: Twenty‐seven consecutive patients were included. LVB and CP were present in all patients. Postprocedural evaluation identified standard cut‐off of 0.3−1 mV useful for LVB identification. An overlap between LVB and CP was observed in 23 (85%) patients. Procedure success was achieved in all patient with effective site at first application in 22 (81%) patients. There was a significant correlation between LVB, CP, and the site of effective ablation (p = .001). Conclusion: We found correlation between LVB and CP with the site of effective ablation, identifying a voltage range useful for standardized LVB identification. These techniques could be useful to identify ablation site and minimize radiation exposure. [ABSTRACT FROM AUTHOR]

To investigate the short- and long-term risks of atrioventricular block and other cardiac conduction disorders associated with being tested for Borrelia burgdorferi (Bb) antibodies or Bb seropositivity as measures of confounding by indication and Bb infection, respectively. We performed a nationwide population-based matched cohort study (Denmark, 1993–2021). We included 52 200 Bb-seropositive individuals (stratified as only Bb- IgM-seropositive [ n = 26 103], only Bb- IgG-seropositive [ n = 18 698], and Bb- IgM-and-IgG-seropositive [ n = 7399]) and two age- and sex-matched comparison cohorts: 104 400 Bb-seronegative individuals and 261 000 population controls. We investigated the risk associated with being tested for serum Bb antibodies and being Bb seropositive. Outcomes were atrioventricular block and other conduction disorders. We calculated short-term odds ratios (aOR) (within 1 month), and long-term hazard ratios (aHR) (after 1 month) adjusted for age, sex, diabetes, chronic heart failure, and kidney disease with 95% CI. Compared with population controls, individuals tested for Bb antibodies had increased short- and long-term risks of atrioventricular block (aOR 47.9, 95% CI: 30.0–76.7, aHR 1.3, 95% CI:1.2–1.3), and other conduction disorders (aOR 18.2, 95% CI: 10.1–32.8, aHR 1.2, 95% CI: 1.1–1.4). Compared with Bb -seronegative individuals, only Bb- IgM-and-IgG-seropositive individuals had increased short-term risk of atrioventricular block (aOR: 2.1, 95% CI: 1.5–3.1). The results suggest that Bb antibody testing is included in the diagnostic work-up of conduction disorders. Finally, that Bb seropositivity is not associated with other conduction disorders than atrioventricular block or with increased long-term risk of conduction disorders. [ABSTRACT FROM AUTHOR]

Smartwatches represent one of the most widely adopted technological innovations among wearable devices. Their evolution has equipped them with an increasing array of features, including the capability to record an electrocardiogram. This functionality allows users to detect potential arrhythmias, enabling prompt intervention or monitoring of existing arrhythmias, such as atrial fibrillation. In our research, we aimed to compile case reports, case series, and cohort studies from the Web of Science, PubMed, Scopus, and Embase databases published until 1 August 2023. The search employed keywords such as "Smart Watch", "Apple Watch", "Samsung Gear", "Samsung Galaxy Watch", "Google Pixel Watch", "Fitbit", "Huawei Watch", "Withings", "Garmin", "Atrial Fibrillation", "Supraventricular Tachycardia", "Cardiac Arrhythmia", "Ventricular Tachycardia", "Atrioventricular Nodal Reentrant Tachycardia", "Atrioventricular Reentrant Tachycardia", "Heart Block", "Atrial Flutter", "Ectopic Atrial Tachycardia", and "Bradyarrhythmia." We obtained a total of 758 results, from which we selected 57 articles, including 33 case reports and case series, as well as 24 cohort studies. Most of the scientific works focused on atrial fibrillation, which is often detected using Apple Watches. Nevertheless, we also included articles investigating arrhythmias with the potential for circulatory collapse without immediate intervention. This systematic literature review provides a comprehensive overview of the current state of research on arrhythmia detection using smartwatches. Through further research, it may be possible to develop a care protocol that integrates arrhythmias recorded by smartwatches, allowing for timely access to appropriate medical care for patients. Additionally, continuous monitoring of existing arrhythmias using smartwatches could facilitate the assessment of the effectiveness of prescribed therapies. [ABSTRACT FROM AUTHOR]

An 80-year-old female was referred to our institution due to transient right upper limb weakness. Transthoracic and transesophageal echocardiography revealed a tumor in the left atrium. The tumor was attached to the posterior wall of the left atrium near the atrioventricular node. Intraoperative pathological examination revealed that the tumor was a myxoma, and complete resection was successfully performed. However, she experienced persistent complete atrioventricular block postoperatively and required pacemaker implantation. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 54-year-old man undergoing radiofrequency ablation for atrial fibrillation, encountering an irregular tachycardia during the procedure. Topics discussed include the mechanism of irregular tachycardia, interpretation challenges due to its irregularity, and the diagnosis of orthodromic reciprocating tachycardia.

This study aimed to elucidate the similarities and differences between amyloid-forming corpora amylacea (CA) in the prostate and lung, examine the nature of CAs in cystic tumors of the atrioventricular node (CTAVN), and clarify the distinctions between amyloid-forming CA and spheroid-type amyloid deposition. We conducted proteomics analyses using liquid chromatography–tandem mass spectrometry with laser microdissection and immunohistochemistry to validate the characteristics of CAs in the lung and prostate. Our findings revealed that the CAs in these organs primarily consisted of common proteins (β2-microglobulin and lysozyme) and locally produced proteins. Moreover, we observed a discrepancy between the histopathological and proteomic analysis results in CTAVN-associated CAs. In addition, while the histopathological appearance of the amyloid-forming CAs and spheroid-type amyloid deposits were nearly identical, the latter deposition lacked β2-microglobulin and lysozyme and exhibited evident destruction of the surrounding tissue. A literature review further supported these findings. These results suggest that amyloid-forming CAs in the lung and prostate are formed through a shared mechanism, serving as waste containers (wasteosomes) and/or storage for excess proteins (functional amyloids). In contrast, we hypothesize that while amyloid-forming CA and spheroid-type amyloid deposits are formed, in part, through common mechanisms, the latter are pathological. [ABSTRACT FROM AUTHOR]

Introduction: The optimal slow pathway (SP) ablation site in cases with an inferiorly located His bundle (HIS) remains unclear. Methods and Results: In 45 patients with atrioventricular nodal reentrant tachycardia, the relationship between the HIS location and successful SP ablation site was assessed in electroanatomical maps. We assessed the location of the SP ablation site relative to the bottom of the coronary sinus ostium in the superior‐to‐inferior (SPSI), anterior‐to‐posterior (SPAP), and right‐to‐left (SPRL) directions. The HIS location was assessed in the same manner. The HIS location in the superior‐to‐inferior direction (HISSI), SPSI, SPAP, and SPRL were 17.7 ± 6.4, 1.7 ± 6.4, 13.6 ± 12.3, and −1.0 ± 13.0 mm, respectively. The HISSI was positively correlated with SPSI (R2 = 0.62; P <.01) and SPAP (R2 = 0.22; P <.01), whereas it was not correlated with SPRL (R2 = 0.01; P =.65). The distance between the HIS and SP ablation site was 17.7 ± 6.4 mm and was not affected by the location of HIS. The ratio of the amplitudes of atrial and ventricular potential recorded at the SP ablation site did not differ between the high HIS group (HISSI ≥ 13 mm) and low HIS group (HISSI < 13 mm) (0.10 ± 0.06 vs. 0.10 ± 0.06; P =.38). Conclusion: In cases with an inferiorly located HIS, SP ablation should be performed at a lower and more posterior site than in typical cases. [ABSTRACT FROM AUTHOR]

Background: Atrioventricular block (AVB) secondary to transient causes can recover with its correction. However, studies assessing predictors of recovery and long‐term recurrence are lacking. Methods: Patients with advanced or complete AVB who had a reversible cause admitted in a single expert center were retrospectively studied. Patients with AVB secondary to acute coronary syndromes were excluded from analysis. Results: In a population of 162 patients, the main factors associated with recovery of rhythm without a permanent pacemaker (PPM) implantation were the presence of chronic kidney disease (CKD) on dialysis (OR 7.6; CI 95% 1.2–47.5 (p =.03)); greater serum potassium levels (OR 2.3; CI 95% 1.28–4.0 (p <.01)), higher dosage of bradycardic drugs (OR 2.2; CI 95% 1.13–4.4 (p =.02)), the association between different bradycardic drugs (OR 9.0; CI 95% 2.02–40.3 (p <.01)) and between drug therapy and hyperkaliemia (OR 5.2; CI 95% 1.8–15.1 (p <.01)). There was an overall high burden of conductions abnormalities which did not correlate with recovery of rhythm (OR 0.5; CI 95% 0.19–1.5 (p =.23)). In 29 patients (17.9%) there was a correction of the AVB. During a maximum follow‐up of 130 months, 24 patients (82.8%) had a recurrence which warranted a PPM. In the overall cohort only five patients (3%) had sustained recovery of rhythm. Conclusions: Recovery of AVB was mainly observed with higher doses of drug therapy, higher serum potassium levels or a combination of factors and regardless of baseline conduction abnormalities. The high rate of recurrence during follow‐up warrants a close follow‐up or PPM implantation at index admission. [ABSTRACT FROM AUTHOR]

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In patients with atrial fibrillation (AF) recurrences after pulmonary vein isolation (PVI), concomitant treatment using anti arrhythmic drugs (AADs) can lead to clinical success. However, patients with atrioventricular (AV) block may not be good candidates for concomitant AAD therapy due to the risk of further worsening of conduction abnormalities. Cardioneuroablation (CNA), as an adjunct to PVI, may offer a solution to this problem. We present a case of a 74-year-old male with paroxysmal AF and first degree AV block in whom CNA following PVI led to PR normalization. The presented case describes an example of CNA utilization in patients with AF undergoing PVI who have concomitant problems with AV conduction and shows that CNA can be sometimes useful in older patients with functional AV block. [ABSTRACT FROM AUTHOR]

This article discusses the mechanism of a narrow QRS tachycardia in a patient with type-A Wolff-Parkinson-White (WPW) syndrome. The patient, a 52-year-old woman, was referred for catheter ablation of the tachycardia. The article presents the case presentation, differential diagnoses, and the final diagnosis of orthodromic reciprocating tachycardia (ORT) via a posteroseptal accessory pathway (AP) with a bystander left lateral AP. The article also explores the clinical insights gained from the case and discusses the challenges in distinguishing between an atrioventricular AP and a nodoventricular pathway. [Extracted from the article]

This article discusses a case of a sexagenarian female who presented with recurrent palpitations and was diagnosed with narrow complex tachycardia. The patient's electrocardiogram (ECG) showed a regular narrow complex short RP tachycardia with intermittent P-wave disappearance in a cyclical pattern. An electrophysiology study confirmed the diagnosis of typical slow-fast atrioventricular nodal re-entrant tachycardia (AVNRT), and successful slow pathway radiofrequency ablation was performed. The article also explores the rare phenomenon of supraventricular tachycardia with ventriculoatrial block and discusses the possible mechanisms and debates surrounding it. [Extracted from the article]

This article discusses the mechanism behind regularly irregular tachycardia, a type of rapid heartbeat. The case presented involves a 62-year-old woman without structural heart disease who was referred for ablation of a narrow QRS complex tachycardia. The article explores the differential diagnoses and diagnostic process, ultimately identifying orthodromic reciprocating tachycardia (ORT) via an accessory pathway (AP) with alternating anterograde limbs over a fast pathway (FP) and slow pathway (SP) as the most likely diagnosis. The article highlights the clinical implications of this type of tachycardia and emphasizes the importance of assessing PR and RP intervals in reaching a correct diagnosis. [Extracted from the article]

This article discusses a case of misdiagnosis from a smartwatch. A 60-year-old man received alerts on his wearable electronic device indicating that he may have atrial fibrillation. However, further testing revealed that he had a rare arrhythmia known as dual AV node non-reentrant tachycardia, or double fire. This condition can be misdiagnosed as supraventricular ectopy, ventricular ectopy, or atrial fibrillation. The article emphasizes the importance of careful physician review of rhythm strips to confirm the diagnosis, especially in cases where wearable devices are used. Treatment for double fire tachycardia typically involves radiofrequency ablation of the slow pathway. [Extracted from the article]

Background: A jump in the atrioventricular (AV) conduction curve is the current clinical criterion of dual-pathway electrophysiology. However, the assumption that a jump indicates a switch from fast pathway (FP) to slow pathway (SP) conduction remains unconfirmed. This study was carried out to investigate whether a jump indeed indicates a transition from FP to SP conduction, and if not, what the potential cause is. Methods: Eighty-one experimental records from rabbit AV nodal preparations containing the following data were analyzed: 1) had at least one AV conduction curve and 2) had recording of His electrogram alternans (a validated new index of dual-pathway conduction). Most cases also had intracellular action potential recordings from the AV nodal fibers. Results: Of the 81 preparations, 11 (13%) showed a jump in the AV conduction curve. The jumps always occurred after the FP to SP transition. The FP–SP transition occurred at prematurity at 196 ± 39 ms versus the jump at 114 ± 13 ms (p < 0.001). The beat with a jump showed an SP–FP pattern in seven and an SP–SP pattern in four preparations. The jumps were always associated with and most likely caused by the formation of intranodal/nodal–atrial reentry and its subsequent conduction, rather than a switch from FP to SP conduction. Conclusion: Contrary to what has been assumed, a transition from FP to SP conduction does not produce a jump in the AV conduction curve. A jump in the AV conduction curve is most likely caused by the formation of intranodal/ nodal–atrial reentry and its subsequent conduction. [ABSTRACT FROM AUTHOR]

Background: Fast-conducting atrial fibrillation misinterpreted as ventricular tachycardia is the leading cause for inappropriate shocks in patients with implantable cardiac defibrillators (ICD). These inappropriate shocks are associated with significant morbidity and mortality and cause great discomfort and stress. Case presentation: We report the case of a patient with ischemic cardiomyopathy, permanent atrial fibrillation, and a single-chamber DF-1 ICD implanted for the primary prevention of sudden cardiac death, who presented for multiple inappropriate internal shocks due to very fast-conducting atrial fibrillation, which was mislabeled as ventricular fibrillation by the ICD. Since the patient was under maximal atrioventricular nodal blocking medical therapy (beta-blockers and digitalis) and we didn't find any reversible causes for the heart rate acceleration, we opted for rate control with atrioventricular node ablation. To counteract the risk of pacing-induced cardiomyopathy in this patient who would become totally pacemaker-dependent, we successfully performed left bundle branch area pacing. Because the patient's ICD had a DF-1 connection and the battery had a long life remaining, we connected the physiological pacing lead to the IS-1 sense-pace port of the ICD. The 6-month follow-up showed an improvement in left ventricular function with no more inappropriate shocks. Conclusions: Left bundle branch area pacing and atrioventricular node ablation in patients with an implantable single-chamber DF-1 defibrillator and fast-conducting permanent atrial fibrillation is a cost-efficient and very effective method to prevent and treat inappropriate shocks, avoiding the use of an additional dual-chamber or CRT-D device. [ABSTRACT FROM AUTHOR]

Background: The mechanism of typical slow‐fast atrioventricular nodal re‐entrant tachycardia (AVNRT) and its anatomical and electrophysiological circuit inside the right atrium (RA) and Koch's Triangle (KT) are not well known. Objective: To identify the potentials of the compact AV node and inferior extensions and to perform accurate mapping of the RA and KT in sinus rhythm (SR) and during AVNRT, to define the tachycardia circuit. Methods: Consecutive patients with typical AVNRT were enrolled in 12 Italian centers and underwent mapping and ablation by means of a basket catheter with small electrode spacing for ultrahigh‐density mapping and a modified signal‐filtering toolset to record the potentials of the AV nodal structures. Results: Forty‐five consecutive cases of successful ablation of typical slow‐fast AVNRT were included. The mean SR cycle length (CL) was 784.1 ± 6 ms and the mean tachycardia CL was 361.2 ± 54 ms. The AV node potential had a significantly shorter duration and higher amplitude in sinus rhythm than during tachycardia (60 ± 40 ms vs. 160 ± 40 ms, p <.001 and 0.3 ± 0.2 mV vs. 0.09 ± 0.12 mV, p <.001, respectively). The nodal potential duration extension was 169.4 ± 31 ms, resulting in a time‐window coverage of 47.6 ± 9%. The recording of AV nodal structure potentials enabled us to obtain 100% coverage of the tachycardia CL during slow‐fast AVNRT. Conclusion: Detailed recording of the potentials of nodal structures is possible by means of multipolar catheters for ultrahigh‐density mapping, allowing 100% of the AVNRT CL to be covered. These results also have clinical implications for the ablation of right‐septal and para‐septal arrhythmias. [ABSTRACT FROM AUTHOR]

Popeye domain-containing (POPDC) proteins selectively bind cAMP and mediate cellular responses to sympathetic nervous system (SNS) stimulation. The first discovered human genetic variant (POPDC1S201F) is associated with atrioventricular (AV) block, which is exacerbated by increased SNS activity. Zebrafish carrying the homologous mutation (popdc1S191F) display a similar phenotype to humans. To investigate the impact of POPDC1 dysfunction on cardiac electrophysiology and intracellular calcium handling, homozygous popdc1S191F and popdc1 knock-out (popdc1KO) zebrafish larvae and adult isolated popdc1S191F hearts were studied by functional fluorescent analysis. It was found that in popdc1S191F and popdc1KO larvae, heart rate (HR), AV delay, action potential (AP) and calcium transient (CaT) upstroke speed, and AP duration were less than in wild-type larvae, whereas CaT duration was greater. SNS stress by β-adrenergic receptor stimulation with isoproterenol increased HR, lengthened AV delay, slowed AP and CaT upstroke speed, and shortened AP and CaT duration, yet did not result in arrhythmias. In adult popdc1S191F zebrafish hearts, there was a higher incidence of AV block, slower AP upstroke speed, and longer AP duration compared to wild-type hearts, with no differences in CaT. SNS stress increased AV delay and led to further AV block in popdc1S191F hearts while decreasing AP and CaT duration. Overall, we have revealed that arrhythmogenic effects of POPDC1 dysfunction on cardiac electrophysiology and intracellular calcium handling in zebrafish are varied, but already present in early development, and that AV node dysfunction may underlie SNS-induced arrhythmogenesis associated with popdc1 mutation in adults. [ABSTRACT FROM AUTHOR]

Objective: The presence of cannon A waves, the so called "frog sign", has traditionally been considered diagnostic of atrioventricular nodal re‐entrant tachycardia (AVNRT). Nevertheless, it has never been systematically evaluated. The aim of this study is to assess the independent diagnostic utility of cannon A waves in the differential diagnosis of supraventricular tachycardias (SVTs). Methods: We prospectively included 100 patients who underwent an electrophysiology (EP) study for SVT. The right jugular venous pulse was recorded during the study. In 61 patients, invasive central venous pressure (CVP) was registered as well. CVP increase is thought to be related with the timing between atria and ventricle depolarization; two groups were prespecified, the short VA interval tachycardias (including typical AVNRT and atrioventricular reciprocating tachycardia (AVRT) mediated by a septal accessory pathway) and the long VA interval tachycardias (including atypical AVNRT and AVRT mediated by a left free wall accessory pathway). Results: The relationship between cannon A waves and AVNRT did not reach the statistical significance (OR: 3.01; p =.058); On the other hand, it was clearly associated with the final diagnosis of a short VA interval tachycardia (OR: 10.21; p <.001). CVP increase showed an inversely proportional relationship with the VA interval during tachycardia (b = −.020; p <.001). CVP increase was larger in cases of AVNRT (4.0 mmHg vs. 1.2 mmHg; p <.001) and short VA interval tachycardias (3.9 mmHg vs. 1.2 mmHg; p <.001). Conclusion: The presence of cannon A waves is associated with the final diagnosis of short VA interval tachycardias. [ABSTRACT FROM AUTHOR]

Introduction: Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia referred for ablation. Periprocedural conduction system damage was a primary concern during AVNRT ablation. This study aimed to assess the incidence of permanent atrioventricular (AV) block and the success rate associated with different types of catheters in slow pathway ablation. Method: A literature search was performed to identify studies that compared various techniques, including types of radiofrequency ablation (irrigated and nonirrigated) and different sizes of catheter tip cryoablation (4, 6, and 8‐mm), in terms of their outcomes related to permanent atrioventricular block and success rate. To assess and rank the treatments for the different outcomes, a random‐effects model of network meta‐analysis, along with p‐scores, was employed. Results: A total of 27 studies with 5110 patients were included in the analysis. Overall success rates ranged from 89.78% to 100%. Point estimation showed 4‐mm cryoablation exhibited an odds ratio of 0.649 (95%CI: 0.202–2.087) when compared to nonirrigated RFA. Similarly, 6‐mm cryoablation had an odds ratio of 0.944 (95%CI: 0.307–2.905), 8‐mm cryoablation had an odds ratio of 0.848 (95%CI: 0.089–8.107), and irrigated RFA had an odds ratio of 0.424 (95%CI: 0.058–3.121) compared to nonirrigated RFA. Conclusion: Our study found no significant difference in the incidence of permanent AV block between the types of catheters. The success rates were consistently high across all groups. These findings emphasize the potential of both RF ablation (irrigated and nonirrigated catheter) and cryoablation as viable options for the treatment of AVNRT, with similar safety and efficacy profile. [ABSTRACT FROM AUTHOR]

The normal heartbeat starts with depolarization of the sino-atrial node to propagate and depolarize, in turn, the atria, atrio-ventricular node and ventricles via the His bundle, the right and left bundle branches and the Purkinje fibres. This electrical impulse depolarizes the ventricles and causes them to contract, thus producing the heartbeat. On a cellular level, the diastolic phase of the myocardial cells is characterized by a negative transmembrane potential. Pacemaker cells have specific ion transporters allowing them to spontaneously trigger rapid depolarization. The repolarization phase is long and is associated with complex ion exchanges across the membrane, that return transmembrane potential to the negative values of the diastolic resting phase. The autonomic nervous system and various anti-arrhythmic drugs can affect components of the action potential and, therefore, alter conduction velocity and the refractory periods of specific parts of the myocardium. [ABSTRACT FROM AUTHOR]