Novel electrophysiological criteria for septal ventricular outflow tract tachycardias requiring a sequential bilateral ablation.

BACKGROUND: Septal ventricular outflow tract ventricular arrhythmias (OT-VAs) are defined as septal origin VAs from the right ventricular or left ventricular OT. Patients with septal OT-VAs may require a sequential bilateral OT ablation. This study aimed to evaluate the electrophysiological characteristics and ablation outcome in patients with septal OT-VAs. METHODS: We retrospectively analyzed the electrocardiography and electrophysiological parameters in 96 patients (mean age 49 ± 15 years, 49 male) undergoing bilateral activation mapping before catheter ablation of idiopathic septal OT-VAs. The patients were categorized into three groups based on the successful ablation sites, including the right ventricular outflow tract (RVOT), RVOT/left ventricular outflow tract (LVOT), and LVOT. RESULTS: Mapping in the three groups demonstrated a gradually decreasing and increasing trend in the earliest activation time obtained from the RVOT and LVOT, respectively. The absolute earliest activation time discrepancy (AEAD) of ≤18 milliseconds could predict the requirement for a sequential bilateral ablation with a sensitivity and specificity of 100.0% and 93.7%, respectively. The small AEAD (≤21 milliseconds) was associated with a higher recurrence rate in patients receiving a successful unilateral ablation, while patients with a longer distance between the bilateral OT earliest activation sites (DEA > 26 mm) increased future recurrences after an initially successful sequential bilateral ablation. CONCLUSIONS: The application of bilateral OT-VA activation mapping and the measurement of the AEAD and DEA provided not only pivotal information for the ablation strategy, but also prognostic implications for recurrences in patients with septal OT-VAs.

Heterogeneous distribution of substrates between the endocardium and epicardium promotes ventricular fibrillation in arrhythmogenic right ventricular dysplasia/cardiomyopathy.

Aims: Whether the distribution of scar in arrhythmogenic right ventricular cardiomyopathy (ARVC) plays a role in predicting different types of ventricular arrhythmias is unknown. This study aimed to investigate the prognostic value of scar distribution in patients with ARVC. Methods and results: We studied 80 consecutive ARVC patients (46 men, mean age 47 ± 15 years) who underwent an electrophysiological study with ablation. Thirty-four patients receive both endocardial and epicardial mapping. Abnormal endocardial substrates and epicardial substrates were characterized. Three groups were defined according to the epicardial and endocardial scar gradient (<10%: transmural, 10-20%: intermediate, >20%: horizontal, as groups 1, 2, and 3, respectively). Sinus rhythm electrograms underwent a Hilbert-Huang spectral analysis and were displayed as 3D Simultaneous Amplitude Frequency Electrogram Transformation (SAFE-T) maps, which represented the arrhythmogenic potentials. The baseline characteristics were similar between the three groups. Group 3 patients had a higher incidence of fatal ventricular arrhythmias requiring defibrillation and cardiac arrest during the initial presentation despite having fewer premature ventricular complexes. A larger area of arrhythmogenic potentials in the epicardium was observed in patients with horizontal scar. The epicardial-endocardial scar gradient was independently associated with the occurrence of fatal ventricular arrhythmias after a multivariate adjustment. The total, ventricular tachycardia, and VF recurrent rates were higher in Group 3 during 38 ± 21 months of follow-up. Conclusion: For ARVC, the epicardial substrate that extended in the horizontal plane rather than transmurally provided the arrhythmogenic substrate for a fatal ventricular arrhythmia circuit.

Novel electrocardiogram and electrophysiological findings for differentiating idiopathic left posterior papillary muscle and left posterior fascicular ventricular arrhythmias.

PURPOSE: Differentiation between idiopathic left posterior fascicular ventricular arrhythmias (LPF-VAs) and posterior papillary muscle (PPM) VAs is of clinical value. This study aimed to develop an algorithm to distinguish PPM-VAs from LPF-VAs. METHODS: This study enrolled 73 consecutive cases, including 31 with PPM-VAs and 42 with LPF-VAs, undergoing successful ablation by using 3D mapping and intracardiac echography to confirm the origin of the VAs. Electrocardiographic and electrophysiological parameters were compared between two groups. RESULTS: The 12-lead electrocardiography of the PPM-VAs was characterized by a longer QRS duration than that in LPF-VAs (154.4 ± 14.5 vs. 132.3 ± 13.1 ms, P < 0.001). A QRS duration ≥133 ms was observed in all patients (100%) with PPM-VAs and 13/42 (31.0%) patients with LPF-VAs. The conduction duration from the earliest left ventricular activation site of the VA to the proximal right bundle branch (VA-RBB) was longer in patients with PPM-VAs than LPF-VAs (51.3 ± 12.2 vs. 23.6 ± 7.7 ms, P < 0.001). Based on the ROC analysis, a VA-RBB >36 ms was recognized in 28/31 patients with PPM-VAs (90.3%) and 2/42 with LPF-VAs (4.8%). An algorithm incorporating a QRS duration of ≥133 ms with a conduction duration of a VA-RBB of >36 ms could yield a sensitivity of 90.3% and specificity of 100% for discriminating PPM-VAs from LPF-VAs. CONCLUSIONS: The novel algorithm incorporating a QRS duration of ≥133 ms with a conduction duration of the VA-RBB of >36 ms could be useful in differentiating PPM-VAs from LPF-VAs.

Increased risk of ventricular tachycardia and cardiovascular death in patients with myocarditis during the long-term follow-up: A national representative cohort from the National Health Insurance Research Database.

The incidence of acute myocarditis complicated with ventricular tachycardia (VT) is unknown. This study aimed to investigate the association between myocarditis and the incidence of VT and mortality. We also aimed to determine the independent predictors that increased the VT risk in those patients. From 2000 to 2004, 13,250 patients with a history of myocarditis were identified from the Taiwan National Health Insurance Research Database. The same number of individuals without heart disease with a matched sex and underlying diseases were selected as the control group. The long-term risks of life-threatening ventricular arrhythmias and mortality in patients with a history of myocarditis were investigated by an adjusted Cox proportional hazards regression. After a mean follow-up of 10.4 ±â€Š2.94 years (interquartile range: 12, 10.19-12), the myocarditis patients showed a higher incidence of new onset VT events compared with healthy controls (5.4% [519 per 100,000 person-year] in the myocarditis group vs, 0.47% [43 per 100,000 person-year] in the healthy controls; adjusted hazard ratio [HR]: 16.1, 95% confidence interval [CI]: 12.4-20.9; P < .001). A higher incidence of cardiovascular death was noted in the myocarditis group than healthy controls (6.52% vs 3.18%; HR: 2.42, 95% CI: 2.14-2.73; P < .001) after adjusting for the multivariate confounders including sex, age, underlying comorbidities, and medications. The results of this study suggested that there was higher incidence of life-threatening VT and mortality during the very long-term follow-up in patients with a history of myocarditis. Future work should focus on an in-depth risk stratification of VT in myocarditis patients.

The use of a novel signal analysis to identify the origin of idiopathic right ventricular outflow tract ventricular tachycardia during sinus rhythm: Simultaneous amplitude frequency electrogram transformation mapping.

INTRODUCTION: The signal characteristics of intracardiac bipolar electrograms at the origin of idiopathic RVOT-VT during sinus rhythm remain unclear. OBJECTIVE: The study sought to develop a novel real-time/online technique, simultaneous amplitude frequency electrogram transformation (SAFE-T), to quantify and localize the diseased ventricular substrate in idiopathic RVOT-VT. METHODS: We retrospectively investigated the intracardiac bipolar recordings in 70 consecutive patients (26% male, mean age 42±12 years) who underwent successful radiofrequency catheter ablation of idiopathic RVOT-VT. We quantified the extent of the frequency fraction of ventricular potentials during sinus rhythm or ventricular pacing using a novel formula, the product of instantaneous amplitude and frequency, and showed that in a 3D geometry as an online SAFE-T map. RESULTS: The characteristics of the HHT spectra of electrograms derived from VT origins demonstrated high frequency components (>70 Hz), which were independent of the rhythm. The density of the abnormal potentials at the VT origins were higher (VT origins, 7.5±2.3 sites/cm2 vs. surrounding myocardium, 1.5±1.3 sites/cm2, p<0.001), and were significantly decreased after ablation (0.7±0.6 sites/cm2, p<0.001). A small region of abnormal potentials were observed in the VT origins (mean area of 1.5±0.8 cm2). The SAFE-T maps predicted the VT origins with 92% sensitivity, 78% specificity with optimal cut-off value of >3.0 Hz·mV. CONCLUSION: The online SAFE-T map was feasible for quantifying the diseased ventricular substrate, irrespective of the rhythm of activation, and can be used to identify the optimal ablation targets for idiopathic RVOT-VT. We found a limited region of abnormal potentials where the RVOT-VT origins were successfully ablated.

A novel method to enhance phenotype, epicardial functional substrates, and ventricular tachyarrhythmias in Brugada syndrome.

BACKGROUND: Fever is associated with the manifestation of Brugada phenotype and ventricular tachycardia/ventricular fibrillation (VT/VF) in patients with Brugada syndrome (BrS). The thermal effect on the pathogenesis of functional substrates in BrS remains unknown. OBJECTIVE: This study aimed to elucidate the thermal effect on BrS phenotype, VT/VF, and electrophysiological characteristics of epicardial functional substrates in BrS. METHODS: We consecutively studied 15 patients with BrS receiving radiofrequency catheter ablation for drug-refractory ventricular tachyarrhythmias. Baseline characteristics, electrocardiographic features, and changes in epicardial functional substrates before and after epicardial warm water instillation (n = 6) were recorded and analyzed. RESULTS: A total of 15 male patients (mean age 41.3 ± 10.3 years) with type 1 BrS presenting with ventricular tachyarrhythmias were consecutively enrolled. Epicardial mapping in 11 patients demonstrated a significantly larger epicardial scar/low-voltage zone (LVZ) area within the right ventricular outflow tract and anterior right ventricular free wall than within the endocardium (6.32 ± 12.74 cm2 vs 52.91 ± 45.25 cm2; P = .007). Epicardial warm water instillation in 6 patients led to a significant enlargement of the functional scar/LVZ area (123.83 ± 35.26 cm2 vs 63.53 ± 40.57 cm2; P = .03), accelerated conduction velocity of the endocardium and epicardium without scar/LVZ area, and increased VT/VF inducibility (16.7% vs 100%; P = .02). Ablation by targeting premature ventricular complexes and/or epicardial abnormal substrates rendered noninducibility of VT/VF and prevented the recurrences of VT/VF. CONCLUSION: Epicardial warm water instillation enhanced functional epicardial substrates, which contributed to the increased inducibility of ventricular tachyarrhythmias in BrS. Ablation by targeting the triggers and abnormal epicardial substrates provided an effective strategy for preventing ventricular tachyarrhythmia recurrences in BrS.

Left Atrial Size and Left Ventricular End-Systolic Dimension Predict the Progression of Paroxysmal Atrial Fibrillation After Catheter Ablation.

INTRODUCTION: Although rare, some paroxysmal atrial fibrillations (AF) still progress despite radiofrequency (RF) ablation. In the study, we evaluated the long-term efficacy of RF ablation and the predictors of AF progression. METHODS: A total of 589 paroxysmal AF patients (404 men and 185 women; aged 54 ± 12 years) who received 3-dimensional mapping and ablation were enrolled. Their clinical parameters and electrophysiological characteristics were collected. They were divided into Group 1 (N = 13, with AF progression) and Group 2 (N = 576, no AF progression). AF progression was defined as recurrence of persistent AF. RESULTS: Group 1 patients had larger left atrial (LA) diameter, larger left ventricle (LV) end-systolic and end-diastolic diameters, poorer LV systolic function, and more amiodarone use at baseline. After 1.2 ± 0.5 procedures, 123 (21%) patients experienced recurrence during 56 ± 29 months' follow-up. In the multivariate analysis, LA diameter (P = 0.018, HR = 1.12, 95% CI = 1.02-1.24) and LV end-systolic diameter (P = 0.005, HR = 1.10, 95% CI = 1.03-1.17) independently predicted AF progression. LA diameter >43 mm and LV end-systolic diameter >31 mm were the best cut-off values for predicting AF progression by ROC analysis. AF progression rate achieved 19% if they had both larger LA diameter (>43 mm) and LV end-systolic diameter (>31 mm). CONCLUSION: RF ablation prevents the progression of paroxysmal AF effectively, except in patients with increased LA diameter and LV end-systolic diameter on echocardiogram, suggesting more aggressive rhythm control therapies should be considered in these patients.

Impact of aortic encroachment to left atrium on non-pulmonary vein triggers of atrial fibrillation.

BACKGROUND: Aortic dilatation was frequently observed in patients with atrial fibrillation (AF) and non-pulmonary vein (PV) triggers are important for mapping and ablation of AF. We hypothesized that the aortic encroachment area over left atrium (LA) could contribute to the local substrate characteristics. METHODS: We studied 32 consecutive patients of AF (age=57.34±8.07, male=30), including 26 paroxysmal and 6 persistent AFs. Anatomic relationship between LA and aorta, and electrophysiological characteristics of the encroachment areas were investigated. IRB approval was taken. RESULTS: The LA bipolar voltage (mean 0.49±0.26mV) was lower at aortic encroached area compared to global LA (mean 1.52±0.48mV) and it was statistically significant (p<0.001). There was a linear correlation between the voltages of LA and distance from the aorta to the aortic encroachment area of LA (p<0.001, R=0.616). Non-PV triggers were observed in 34.37% (n=11) of total patients. The initiation of AF in aortic encroached area was seen in 45.45% (n=5) of non-PV trigger and 15.62% of total patients. All the patients were followed up for 6months and 4 (14.81%) out of 27 patients without trigger at aortic encroached site of LA and 1 (20%) out of 5 patients with trigger at aortic encroached site of LA had recurrence of AF. CONCLUSION: The aorta contributed to low voltages on its encroachment area over the anterior wall of LA. Non-pulmonary vein triggers originating from the aortic encroachment area were found in 15.62% of total patients. Careful evaluation of the anatomical relationship between LA and aorta is important during AF ablation for a better long term outcome.

The Effect of Tai Chi Chuan on Obstacle Crossing Strategy in Older Adults.

The purpose of this study was to determine the effect of Tai Chi Chuan on the strategies of obstacle-crossing behavior in older adults aged over 65 years. Fifteen Tai Chi group (TCG) participants were compared with 15 general group (GG) participants. Kinematic parameters (by Vicon motion analysis system) and ground reaction forces (by Kistler force plates) were synchronously recorded. A two-way mixed-design ANOVA (α = 0.05) was used to test the effects of the group and the obstacle height. The TCG performed significantly faster stride velocities, longer stride lengths, and shorter stride times than GG while crossing the obstacles. TCG could also produce significantly larger forward ground reaction forces to propel the body and were able to make a significantly greater flexion angle of the hip of the leading leg compared with the GG. It was concluded that the TCG adopted a different strategy with GG to cross the obstacles and completed the crossing behavior more effectively.

History of hyperthyroidism and long-term outcome of catheter ablation of drug-refractory atrial fibrillation.

BACKGROUND: Hyperthyroidism is a known reversible cause of atrial fibrillation (AF). However, some patients remain in AF despite restoration of euthyroid status. OBJECTIVE: The purpose of this study was to compare the electrophysiologic characteristics and long-term ablation outcome in AF patients with and without history of hyperthyroidism. METHODS: The study enrolled 717 consecutive patients with AF who underwent first AF ablation, which involved pulmonary vein (PV) isolation in paroxysmal AF and additional substrate modification in nonparoxysmal AF patients. Eighty-four patients (12%) with hyperthyroidism history were compared to those without. Euthyroid status was achieved for ≥3 months before ablation in hyperthyroid patients. RESULTS: Patients with hyperthyroid history were associated with older age, more female gender, lower mean right atrial voltage, higher number of PV ectopic foci (1.3 ± 0.4 vs 1.0 ± 0.2, P < .01), and higher prevalence of non-PV foci (42% vs 23%, P < .01). Ectopic foci from ligament of Marshall were demonstrated more often in hyperthyroid patients (7.1% vs 1.6%, P < .01) in whom alcohol ablations were required. After propensity score matching for potential covariates, history of hyperthyroidism was an independent predictor of AF recurrence after single procedure (hazard ratio 2.07, 95% confidence interval 1.27-3.38). AF recurrence rates after multiple procedures were not different between patients with and those without hyperthyroid history. CONCLUSION: Patients with hyperthyroid history had a significantly higher number of PV ectopies and higher prevalence of non-PV ectopic foci compared to euthyroid patients, which resulted in a higher AF recurrence rate after a single procedure.

Ground reaction force characteristics of Tai Chi push hand.

Push Hand is an advanced training technique for the Yang-style old frame 108 forms Tai Chi Chuan. It is performed by two practitioners. To clarify how people use forces during Push Hand training, it is important to review the ground reaction force (GRF). Here, we quantify the characteristics of the GRF during Push Hand training. Kinematic data and GRF data from 10 Tai Chi Chuan practitioners (29.9 ± 7.87 years) were synchronously recorded using a three-dimensional motion analysis system (200 frames · s(-1)) and three-dimensional force plates (1000 Hz). The resultant GRF for both feet for the 0%, 50% and 100% phases of attack and defence were compared to body weight using a paired-samples t-test. The differences in the resultant GRF between the 0%, 50% and 100% phases of attack and defence were tested by one-way repeated-measures ANOVA. The significance level was set to 0.05. The total resultant GRF was almost equal to the participant's body weight in push hand. This result was consistent throughout the entire push hand process. Our results revealed that the GRF was comparable to the body weight, implying that practitioners do not push or resist their opponents during the push hand process.