Atrial Potentials Research Articles

Novel electroanatomical map for permanent his bundle pacing: the Mont Blanc approach - influence of the learning curve and procedural outcome.

Pacing the specific conduction system like the Bundle of His (HB) can lead to more physiologic activation patterns compared to traditional right ventricular apical pacing. The aim of this study was to estimate the feasibility and value of electroanatomical mapping (EAM) for HB pacing during the learning curve and its impact on procedural outcome. Fifteen consecutive patients were treated using EAM of the His bundle region before implantation. Voltage and activation maps of HB potentials were performed. The activation time from His potential to R wave (ECG-reference) was measured and correlated to the HV interval. The atrial and ventricular potentials were blended so the active window could only see the His potential. After completing the activation map, it was transformed into a peak-to-peak voltage map of the HB. With reversed black and white colour scale, the exact point of the maximal His signal amplitude was visualized. Procedural data for the implantation were analysed using this innovative approach. The average total procedural time and fluoroscopy time was 88.2 ± 19.1 min and 10.9 ± 4.5 min, respectively. The 3D mapping time was 18.4 ± 5.1 min. The 13.9 ± 5.1 His potential points were needed in average to complete the map. No periprocedural complications were seen in this cohort. In 86.7% of cases, His bundle pacing was successful. The average threshold for the His bundle stimulation and the R-wave amplitude was 1.62 ± 1 V (@1.0 ms) and 4.8 ± 3.2 mV, respectively. The pacing impedance was 513.5 ± 102.8 Ω. Average paced QRS complex width was 116.9 ± 20.3ms. On average 2.6 ± 1.6 lead positions were targeted to find the optimal pacing site. Electroanatomical mapping-guided implantation of His-bundle leads can facilitate the identification of optimal pacing sites and allow to minimize procedure and fluoroscopy times even during the phase of the learning curve.

The use of an autologous right atrial free wall as a patch for closure of atrial septal defects.

Various patch materials to close large atrial septal defects (ASDs) are autologous pericardium or a large of prosthetic patches which may be associated with infrequent but definite problems. We describe our experience with the use of the right atrial free wall patch over the last two decades. Between July 1998 and December 2017, 157 patients (mean age 14.7 ± 13.9 years), underwent ASD closure using the right atrial free wall patch. Associated lesions were severe mitral regurgitation (n = 24), partial anomalous pulmonary venous drainage (n = 15), ASD closure occurring after myxoma excision (n = 12) total anomalous pulmonary venous drainage (n = 2) and tricuspid regurgitation (n = 2). Surgery was uneventful in all patients. All patients underwent serial electrocardiography and echocardiography. Follow-up in 140 of 155 survivors was 103.6 ± 0.6 months. One hundred forty of one hundred fifty-five survivors are in sinus rhythm and three have persistent atrial fibrillation. Twenty-four hours of Holter monitoring (n = 19) revealed normal sinus rhythm in all but three patients, with occasional atrial ectopics in one patient; four were lost to follow-op. Electrophysiological studies in seven consenting patients, 9 to 16 months following ASD closure showed normal atrial potentials from the site of the patch. The autologous right atrial free wall is a safe patch material for ASD closure. Its advantages are that it is autologous, endothelialized, probably viable, and carries a low risk of thromboembolism. Studies with a larger number of patients with longer follow are needed to further confirm these findings.

(Retraction Request) Electrophysiological Characteristics and Radiofrequency Catheter Ablation Treatment of Idiopathic Ventricular Arrhythmias Successfully Ablated From the Ostium of the Coronary Sinus.

Background Idiopathic ventricular arrhythmias (VAs) rarely arise from the epicardium at the crux of the heart. However, the electrophysiological characteristics of VAs successfully ablated from the ostium of the coronary sinus (CSO) have not yet been documented.Methods and Results:Electrocardiographic and electrophysiological data were analyzed in patients with idiopathic VAs successfully ablated from the CSO.Among 309 patients with idiopathic VAs treated with radiofrequency catheter ablation (RFCA), 6 (1.94%; 3 men; age: 66.3±9.7 years) had VAs successfully ablated from the CSO. Only 1 patient had sustained ventricular tachycardia. The morphology of the QRS showed a left superior axis and QS pattern in leads III and aVF. Furthermore, the precordial maximum deflection index was >0.55 in all patients and a right bundle branch block pattern was recorded in 5 of 6 patients. All VAs were successfully eliminated by RFCA within the CSO. Intracardiac ECGs at sites where VAs were eliminated by RFCA showed clear atrial and ventricular potentials (atrial amplitude: 0.21±0.11 mV; ventricular amplitude: 0.43±0.24 mV), except in 1 case of atrial fibrillation. No patients had recurrence during the 3.4±1.8-year follow-up period. Conclusions The idiopathic VAs in our study were eliminated by RFCA within the CS, where a clear atrial amplitude was recorded.

Ripple map guided catheter ablation targeting abnormal atrial potentials during sinus rhythm for non-paroxysmal atrial fibrillation.

Abnormal atrial potential (AAP) during sinus rhythm may be a critical ablation target for atrial fibrillation. However, the assessment of local electrograms throughout the left atrium is difficult. Thus, we sought to investigate the effectiveness of Ripple map guided AAP ablation. AAP areas were determined by Ripple mapping on the CARTO system in 35 patients (Ripple group) by marking the area where small deflections persisted after the first deflection wavefront had passed. Following pulmonary vein isolation, AAP areas were ablated. If AAP areas were located on the left atrial posterior wall, the posterior wall was isolated. The outcome of this approach was compared with that of 66 patients who underwent an empirical linear ablation approach (control group). There were no differences in patient characteristics between the groups. The total radiofrequency application time and procedure time were shorter in the Ripple group than in the control group (radiofrequency application time, 48 ± 14 minutes vs61 ± 13 minutes,P < .001; procedure time, 205 ± 30 minutes vs221 ± 27 minutes,P = .013). Gastroparesis occurred in one patient in each group (P = .645), but in both cases this was relieved with conservative therapy. Kaplan-Meier analysis revealed that rate of freedom from atrial arrhythmia was higher in the Ripple group than in the control group (91% vs74% during the 12 months'follow up;P = .040). Ripple map guided AAP ablation effectively suppressed atrial arrhythmia in patients with non-paroxysmal AF.

Mapping potentials adjacent to the cavo-tricuspid isthmus ablation line during incremental pacing: A feasible and highly accurate maneuver to confirm complete CTI conduction block.

The diagnostic accuracy of incremental atrial pacing (IP) to determine complete cavo-tricuspid isthmus (CTI) block during typical atrial flutter (AFL) ablation is limited by both an extensive/nonlinear ablation and/or the presence of intra-atrial conduction delay elsewhere in the right atrium. We examined the diagnostic performance of an IP variant based on the assessment of the atrial potentials adjacent to the ablation line which aims at overcoming both limitations. From a prospective population of 108 consecutive patients, 15 were excluded due to observation of inconclusive CTI ablation potentials precluding for a straight comparison between the IP maneuver and its variant. In the remaining 93, IP was performed from the low lateral right atrium and the coronary sinus ostium, with the ablation catheter positioned both at the CTI line and adjacent (<5 mm) to its septal and lateral aspect. The IP variant consisted of measuring the interval between the two atrial electrograms situated on the same side of the ablation line, opposite to the pacing site, a ≤10 ms increase indicating complete CTI block. The IP maneuver and its variant were consistent with complete CTI block in 82/93 (88%) and 87/93 (93%) patients, respectively. Four patients had AFL recurrence during follow-up: 2/4 and 4/4 had been adequately classified as incomplete block by the IP maneuver and its variant, respectively. Twenty-three patients (24%) had significant intra-atrial conduction delay elsewhere in the right atrium. The IP maneuver and its variant were suggestive of an incomplete CTI block in 11/23 and 4/23 in this setting (P = .028), with the later best predicting subsequent AFL relapses (2/12 vs 2/4, P = .01). The IP variant, which was designed to overcome the limitations of the conventional IP maneuver, accurately distinguishes complete from incomplete CTI block and helps to predict AFL recurrences after ablation.

Triggered Ca2+ Waves Induce Depolarization of Maximum Diastolic Potential and Action Potential Prolongation in Dog Atrial Myocytes.

We have identified a novel form of abnormal Ca2+ wave activity in normal and failing dog atrial myocytes which occurs during the action potential (AP) and is absent during diastole. The goal of this study was to determine if triggered Ca2+ waves affect cellular electrophysiological properties. Simultaneous recordings of intracellular Ca2+ and APs allowed measurements of maximum diastolic potential and AP duration during triggered calcium waves (TCWs) in isolated dog atrial myocytes. Computer simulations then explored electrophysiological behavior arising from TCWs at the tissue scale. At 3.3 to 5 Hz, TCWs occurred during the AP and often outlasted several AP cycles. Maximum diastolic potential was reduced, and AP duration was significantly prolonged during TCWs. All electrophysiological responses to TCWs were abolished by SEA0400 and ORM10103, indicating that Na-Ca exchange current caused depolarization. The time constant of recovery from inactivation of Ca2+ current was 40 to 70 ms in atrial myocytes (depending on holding potential) so this current could be responsible for AP activation during depolarization induced by TCWs. Modeling studies demonstrated that the characteristic properties of TCWs are potentially arrhythmogenic by promoting both conduction block and reentry arising from the depolarization induced by TCWs. Triggered Ca2+ waves activate inward NCX and dramatically reduce atrial maximum diastolic potential and prolong AP duration, establishing the substrate for reentry which could contribute to the initiation and maintenance of atrial arrhythmias.

3-Dimensional Transseptal Puncture Based on Electrographic Characteristics of Fossa Ovalis: A Fluoroscopy-Free and Echocardiography-Free Method

ObjectivesThis study sought to define electrographic characteristics of the fossa ovalis (FO) and use these findings in developing a 3-dimensional (3D) transseptal puncture (TSP) technique that does not rely on fluoroscopy or echocardiography. BackgroundTraditional TSP method based on fluoroscopy or echocardiography is basically a 2-dimensional (2D) technique. A valid 3D method of TSP has not been sufficiently clarified. MethodsThe shape of the FO and its center were “electrographically” defined by comparing their potential characteristics to those of the surrounding limbus. After validation by intracardiac echocardiography, this FO mapping was incorporated into 3D electroanatomical reconstruction of the right atrium. Using a new catheter connection, the transseptal needle could be visualized nonfluoroscopically and directed to the precise localization of the FO on the electroanatomic map. ResultsA total of 276 patients who underwent atrial fibrillation ablation were included. The central FO was identified in all cases with atrial electrogram voltage at 0.33 ± 0.21 mV. The amplitude of atrial potential at the FO annulus was 1.70 ± 0.72 mV (p < 0.001). By incorporating the electrographically defined FO into the 3D electroanatomic mapping and using the transseptal needle visualization approach, TSP was successful in all patients, with 91% of the cases at the first attempt. Atrial fibrillation ablation was completed in all patients with no major complication. ConclusionsElectrographic characteristics of the FO center are distinct from those of the surrounding regions. This information can be leveraged to define the FO on 3D electroanatomic mappings, thereby facilitating safe TSP without the need of ancillary imaging with fluoroscopy or echocardiography.

Relation of Fractionated Atrial Potentials With the Vagal Innervation Evaluated by Extracardiac Vagal Stimulation During Cardioneuroablation.

Vagal hyperactivity is directly related to several clinical conditions as reflex/functional bradyarrhythmias and vagal atrial fibrillation (AF). Cardioneuroablation provides therapeutic vagal denervation through endocardial radiofrequency ablation for these cases. The main challenges are neuromyocardium interface identification and the denervation control and validation. The finding that the AF-Nest (AFN) ablation eliminates the atropine response and decreases RR variability suggests that they are related to the vagal innervation. Prospective, controlled, longitudinal, nonrandomized study enrolling 62 patients in 2 groups: AFN group (AFN group 32 patients) with functional or reflex bradyarrhythmias or vagal AF treated with AFN ablation and a control group (30 patients) with anomalous bundles, ventricular premature beats, atrial flutter, atrioventricular nodal reentry, and atrial tachycardia, treated with conventional ablation (non-AFN ablation). In AFN group, ablation delivered at AFN detected by fragmentation/fractionation of the endocardial electrograms and by 3-dimensional anatomic location of the ganglionated plexus. Vagal response was evaluated before, during, and postablation by 5 s noncontact vagal stimulation at the jugular foramen, through the internal jugular veins (extracardiac vagal stimulation [ECVS]), analyzing 15 s mean heart rate, longest RR, pauses, and atrioventricular block. All patients had current guidelines arrhythmia ablation indication. Preablation ECVS induced sinus pauses, asystole, and transient atrioventricular block in both groups showing a strong vagal response (P=0.96). Postablation ECVS in the AFN group showed complete abolishment of the cardiac vagal response in all cases (pre/postablation ECVS=P<0.0001), demonstrating robust vagal denervation. However, in the control group, vagal response remained practically unchanged postablation (P=0.35), showing that non-AFN ablation promotes no significant denervation. AFN ablation causes significant vagal denervation. Non-AFN ablation causes no significant vagal denervation. These results suggest that AFNs are intrinsically related to vagal innervation. ECVS was fundamental to stepwise vagal denervation validation during cardioneuroablation. Visual Overview A visual overview is available for this article.

The Electrical Isolation of the Left Atrial Posterior Wall in Catheter Ablation of Persistent Atrial Fibrillation.

This study explored whether complete electrical isolation of the left atrial (LA) posterior wall improves the rhythm outcome of catheter ablation of persistent atrial fibrillation (AF). Although the STAR AF2 (Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial Part II) proved no additional benefit of empirical extra-pulmonary vein (PV) LA ablation, the long-term recurrence rate after circumferential PV isolation (CPVI) alone remains high. We randomly assigned 217 patients with persistent AF (83.1% men, age 58.7 ± 10.8 years, 73.3% long-standing persistent AF) to ablation with CPVI alone (CPVI group) or CPVI with a POsterior wall Box Isolation (POBI group). The endpoint of the POBI group was the elimination of the posterior atrial potentials by roof and posterior inferior lines and touch-up focal ablation. After a mean follow-up of 16.2 ± 8.8months, the clinical recurrence rate did not significantly differ between the 2 groups (23.8% vs. 26.5%; p=0.779) in the CPVI and POBI groups. The recurrence rate for atrial tachycardias (16.0% vs. 11.1%; p=0.913) and cardioversion rates (6.7% vs. 13.7%; p=0.093) to control clinical recurrences also did not significantly differ between the 2 groups. At the final follow-up, sinus rhythm was maintained without antiarrhythmic drug in 50.5% and 55.9% in the CPVI and POBI groups, respectively (p=0.522). No significant difference was found in the major complication rates between the 2 groups, but the total ablation time was significantly longer in the POBI group (4,289 ± 1,837s vs. 5,365 ± 2,358 s; p<0.001). In patients with persistent AF, an empirical complete POBI did not improve the rhythm outcome of catheter ablation or influence the type of recurrent atrial arrhythmia. (Comparison of Circumferential Pulmonary Vein Isolation Alone Versus Linear Ablation in Addition to Circumferential Pulmonary Vein Isolation for Catheter Ablation in Persistent Atrial Fibrillation: Prospective Randomized Controlled Trial; NCT02721121).

Electrical properties of the myocardium in patients with arterial hypertension combined with subclinical hypothyroidism

Late atrial and ventricular potentials are non-invasive electrocardiographic criteria for presence of high arrhythmic readiness and risk of life-threatening arrhythmias. The electrical properties of the myocardium in patients with stage II arterial hypertension (AH) combined with subclinical hypothyroidism have not been studied previously.Aim. To study the changes of electrical properties of the atrial and ventricular myocardium in patients with AH combined with subclinical hypothyroidism.Materials and methods. The criteria for inclusion in the study were the presence of stage II AH without thyroid gland pathology and combined with subclinical hypothyroidism (SH) (for patients of the main group). Depending on the level of thyroid-stimulating hormone (TSH), the AH patients were divided into 2 groups – with normal (0.4–4.0 mU/ml) and moderately elevated level of TSH (4.0–15.6 mU/l, with normal levels of thyroid hormones).The group of patients with AH without SH included 92 patients (women – 81.52 % (75), men – 18.48 % (17)); the group of patients with AH with concomitant SH included 30 patients (women – 86.7% (26), men – 13.3 % (4)). All patients underwent 24-h BP monitoring and ECG (combined ECG and BP monitor “Kardiotechnica-04-AD-3”,St. Petersburg,Russia). A 40 Hz cutoff filter was used recording in the X, Y, Z orthogonal leads. Data were processed with the help of a program Statistica 6.0. Data were presented as the median and inter-quartile range of Me (25 %; 75 %).Results. In AH patients without concomitant subclinical hypothyroidism, unlike in relatively healthy patients, late atrial potential predominance was seen (63 % vs. 84 %; P = 0.0419) with a 16.4 times (P = 0.018) increase in the number of premature atrial contractions. Also, in patients with AH without concomitant subclinical hypothyroidism late ventricular potentials (LVPs) occurred 5.7 times more often (6 % vs. 34 %, P = 0.0302) and were associated with a significant (P = 0.004) increase in the number of premature ventricular contractions per day in this category of patients.In SH patients with a concomitant subclinical hypothyroidism, unlike in relatively healthy individuals, atrial ectopic activity was significantly more predominant (LAP was found in 87 %; versus 63 %, P = 0.0498), which was accompanied by a logical 27.2 times (P = 0.038) increase in the number of premature atrial contractions and ventricular ectopic activity. Changes in the electrical properties of the ventricles were accompanied by an increase in the percentage of detected LVPs (77 % versus 6 %, P = 0.0001), which was associated with a significant (P = 0.001) increase in the number of premature ventricular contractions per day in this category of patients (441.53 ± 1414.97 versus 0.00 ±0.00 inalmost healthy subjects, P = 0.001).AH patients with and without concomitant SH did not differ from each other in terms of indexes characterizing late atrial potentials. There was also no statistically significant difference in the number of premature atrial contractions (P = 0.527), paired premature atrial contractions (P = 0.449), salvos of atrial premature contractions (P = 0.314). However, in AH patients with concomitant SH there was a significant increase in the ectopic activity of the ventricles – LVPs were found in 77 % vs. 33 % in individuals without SH (P = 0.0001), changes in the electrical properties of ventricles in AH patients with concomitant SH were also associated with an increase in the number of premature ventricular contractions by 6.69 times (from 42.56 ± 36.96 to 441.53 ± 1414.97, P = 0.026) compared with the same index in patients with AH without concomitant SH, indicating the negative effect of SH on the electrical properties of the ventricles.Conclusions. In patients with stage II arterial hypertension in comparison to relatively healthy subjects, indicators that characterize the late potentials of the atria and ventricles are significantly changed, which is accompanied by an increase in the number of supraventricular and ventricular rhythm disorders. Subclinical hypothyroidism causes an additional pro-arrhythmic effect on the ventricular myocardium in arterial hypertension.

Utility of local atrial electrogram pattern for predicting left main coronary artery anatomical distance during mapping in the left pulmonary sinus of valsalva.

Ablation of right ventricular outflow tract (RVOT) ventricular arrhythmia (VA) within the left pulmonary sinus of Valsalva (LPSV) may increase the risk of left main coronary artery (LMCA) injury. To delineate the anatomical characteristics between LMCA and LPSV and their association with atrial potential (AP) mapping in LPSV. A total of 104 consecutive patients with RVOT-VA undergoing cardiac-gated computed tomography coronary angiography (CTCA) after ablation were retrospectively analyzed. The LMCA-LPSV anatomic relationship was classified into three types based on the CTCA measurements. Types 1 and 2 had a shorter LMCA-LPSV distance than that of type 3 (P < .001). The left atrial appendage (LAA)-LMCA distance and LAA-LPSV distance were associated with the incidence of AP in LPSV (odds ratio [OR] = 3.43, 95% confidence interval [CI]: 1.86-6.34, P < .001; OR = 1.196, 95% CI: 1.09-1.31, P < .001, respectively). Furthermore, the LMCA-LPSV distance showed a linear correlation with the LAA-LPSV distance (r2 = 0.93, P < .001). According to receiver operating characteristic (ROC) analysis, a LMCA-LPSV distance <5.4 mm could predict the possibility of AP during LPSV mapping (sensitivity 83%, specificity 81%, and area under the ROC curve 0.86). The presence of AP in the LPSV may be useful to predict a short distance from the LPSV to the LMCA and to identify patients at higher risk of LMCA injury. This information may contribute to efficient and safe ablation in this area but should be confirmed in future studies.

QT prolongation and variability: new ECG signs of atrial potentials dispersion before atrial fibrillation onset.

QT interval may be considered an indirect marker of atrial repolarization. Aim of our study was to verify if QT interval variations precede the onset of atrial fibrillation (AF). We analyzed 21 AF onsets recorded at 24-h Holter ECG. Triggering supraventricular extrabeats (TSVEB) were identified and matched to nontriggering supraventricular extrabeats (NTSVEB) with the same prematurity index. QT and QTc intervals and their variability (max-min QT interval) were measured in the 10 beats preceding TSVEB and NTSVEB. QTc (470.1 ± 56.7 vs. 436.7 ± 25.6 ms; P = 0.006), QT (36.8 ± 13.1 vs. 21.1 ± 10.1 ms; P = 0.001) and QTc variability (41.5 ± 15.8 vs. 23.1 ± 11.9; P = 0.001) significantly varied between TSVEB and NTSVEB. By stratifying AF onsets in vagal (n = 10) and adrenergic (n = 11) according to Heart Rate Variability, significant differences emerged concerning QT (35.20 ± 16.48 vs. 22.70 ± 10.23 ms, P = 0.006) and QTc variability (39.30 ± 18.32 vs. 25.60 ± 12.91 ms, P = 0.029) for vagal onsets and QTc (477.73 ± 57.50 vs. 438.00 ± 28.55 ms, P = 0.045), QT (38.36 ± 9.79 vs. 19.73 ± 10.21 ms, P = 0.005) and QTc variability (43.55 ± 13.72 vs. 20.82 ± 11.01 ms, P = 0.004) for adrenergic onsets. By stratifying AF onsets in type I (n = 7) or II (n = 14) according to a cycle length variation in the 30 s before the onset greater or smaller than 10% respectively, significant differences were noted concerning QTc (477.73 ± 57.50 vs. 438 ± 28.55 ms, P = 0.045), QT (43.55 ± 13.72 vs. 20.82 ± 11.01 ms, P = 0.005) and QTc variability (43.55 ± 13.72 vs. 20.82 ± 11.01 ms, P = 0.004) in type I and QT (35.20 ± 16.48 vs. 22.70 ± 10.23 ms, P = 0.006) and QTc variability (39.30 ± 18.32 vs. 25.60 ± 12.91 ms, P = 0.029) in type II onsets. Prolongation and QT variability represent a relevant substrate marker in the genesis of AF, independently of the trigger type.

Left Atrial Electromechanical Remodeling Following 2 Years of High-Intensity Exercise Training in Sedentary Middle-Aged Adults.

Moderate intensity exercise is associated with a decreased incidence of atrial fibrillation. However, extensive training in competitive athletes is associated with an increased atrial fibrillation risk. We evaluated the effects of 24 months of high intensity exercise training on left atrial (LA) mechanical and electric remodeling in sedentary, healthy middle-aged adults. Sixty-one participants (53±5 years) were randomized to 10 months of exercise training followed by 14 months of maintenance exercise or stretching/balance control. Fourteen Masters athletes were added for comparison. Left ventricular (LV) and LA volumes underwent 3D echocardiographic assessment, and signal-averaged electrocardiographs for filtered P-wave duration and atrial late potentials were completed at 0, 10, and 24 months. Extended ambulatory monitoring was performed at 0 and 24 months. Within and between group differences from baseline were compared using mixed-effects model repeated-measures analysis. Fifty-three participants completed the study (25 control, 28 exercise) with 88±11% adherence to assigned exercise sessions. In the exercise group, both LA and LV end diastolic volumes increased proportionately (19% and 17%, respectively) after 10 months of training (peak training load). However, only LA volumes continued to increase with an additional 14 months of exercise training (LA volumes 55%; LV end diastolic volumes 15% at 24 months versus baseline; P<0.0001 for all). The LA:LV end diastolic volumes ratio did not change from baseline to 10 months, but increased 31% from baseline in the Ex group ( P<0.0001) at 24 months, without a change in controls. There were no between group differences in the LA ejection fraction, filtered P-wave duration, atrial late potentials, and premature atrial contraction burden at 24 months and no atrial fibrillation was detected. Compared with Masters athletes, the exercise group demonstrated lower absolute LA and LV volumes, but had a similar LA:LV ratio after 24 months of training. Twenty-four months of high intensity exercise training resulted in LA greater than LV mechanical remodeling with no observed electric remodeling. Together, these data suggest different thresholds for electrophysiological and mechanical changes may exist in response to exercise training, and provide evidence supporting a potential mechanism by which high intensity exercise training leads to atrial fibrillation. URL: https://www.clinicaltrials.gov . Unique identifier: NCT02039154.

New tailored approach using a revised assessment of fragmented potentials for persistent atrial fibrillation: Early area defragmentation by modified CFAE module.

Pulmonary vein isolation (PVI) is widely performed for atrial fibrillation (AFib). However, it is insufficient to maintain sinus rhythm (SR) in persistent and long persistent atrial fibrillation (Per-AFib). Ablation of complex fractionated atrial electrograms (CFAEs) is currently classified as class IIb, However, the concept of length of potential was different between the current CFAE module of CARTO system and the definition of CFAE potential. The current CFAE module was configured in the shortest complex interval (SCI) mode, in which the meaning of length of potential was the interval of each component of fragmented potentials. That was a part of the potential. On the other hand, the meaning of the definition of CFAE potential was the length of fragmented potential itself. The purpose of this study was to essentially evaluate fragmented potentials by revisiting in interval confidence level (ICL) mode and express them on the map and prospectively investigate the efficacy and prognosis of a new tailored approach for defragmentation, which is called early area defragmentation (EADF). We acquired atrial potentials by modified CFAE module in ICL mode (K-CFAE potential) and visualized the distribution of K-CFAE potential (K-CFAE map). We performed PVI, and we ablated the fragmented areas based on the K-CFAE map. We enrolled 77 patients in this study (control group: 84 patients). After 24-month follow-up, 75.3% were able to maintain SR. K-CFAE mapping faithfully represented the distribution of fragmented areas. PVI, together with our new tailored approach, EADF, was successful in treating Per-AFib.

Moderate alcohol consumption is associated with atrial electrical and structural changes: Insights from high-density left atrial electroanatomic mapping

Regular alcohol intake is an important modifiable risk factor associated with atrial fibrillation (AF) and left atrial (LA) dilation. The purpose of this study was to determine the impact of different degrees of alcohol consumption on atrial remodeling using high-density electroanatomic mapping. We enrolled 75 patients before AF ablation to undergo high-density LA mapping (CARTO, Biosense Webster) using a multipolar catheter. The Confidense algorithm was used to create maps during distal coronary sinus pacing at 600 ms. Bipolar voltage and complex atrial activity were assessed, and isochronal activation maps were created to determine global conduction velocity (CV). Patients were classified as lifelong nondrinkers, mild drinkers (2-7 drinks/week), or moderate drinkers (8-21 drinks/week). High-density electroanatomic mapping (mean 1016 ± 445 points per patient) was performed on 25 lifelong nondrinkers, 25 mild drinkers (4.4 ± 2.3 drinks/week), and 25 moderate drinkers (14.0 ± 4.2 drinks/week). Moderate drinkers had significantly lower mean global bipolar voltages (1.53 ± 0.62 mV vs 1.89 ± 0.45 mV; P= .02), slower CV (33.5 ± 14.4 cm/s vs 41.7 ± 12.1 cm/s; P=.04), and a higher proportion of complex atrial potentials (7.8% ± 4.7% vs 4.5% ± 2.7%; P = .004) compared to nondrinkers. Global voltage and CV did not differ significantly in mild drinkers, but there was a significant increase in global complex potentials (6.6% ± 4.6%; P = .04) and regional low-voltage zones (<0.5 mV) in the septum and lateral wall (P <.05) compared with nondrinkers. Regular moderate alcohol consumption, but not mild consumption, is an important modifiable risk factor for AF associated with lower atrial voltage and conduction slowing. These electrical and structural changes may explain the propensity to AF in regular drinkers.

Is proximal coronary sinus involved in the circuit in some cases of ECG "typical" atrial flutter?

It is commonly conceived that coronary sinus (CS) participates in atrial flutter (AFL) circuit but limited to the fibers surrounding its ostium. We evaluated the involvement of proximal CS in typical AFL. Twenty AFL patients underwent entrainment mapping using postpacing interval minus AFL cycle length (PPI-AFL CL) including CS where a decapolar catheter was positioned with proximal bipole 1 cm from the ostium. We compared patients with proximal CS within the circuit (group 1, PPI-AFL CL ≤ 20 ms + concealed entrainment) and those without (group 2, PPI-AFL CL > 20 ms). Group 1 patients were older, 77.5 ± 4 vs 71 ± 12 years (P < 0.05). No difference was found in AFL CL, PPI-AFL CL at cavotricuspid isthmus (CTI) entry, plateau, and septal site. Group 1 patients had shorter PPI-AFL CL at proximal CS (9 ± 3 vs 40 ± 15 ms; P < 0.001) and fragmented mesodiastolic CS atrial potentials (APs) (106 ± 27 vs 58.5 ± 22 ms; P < 0.001). A mid-septal unexcitable scar was found in five of eight group 1 patients vs one of 12 group 2 patients (P < 0.05). All were ablated at CTI. A patient had AFL recurrence and underwent a second attempt: PPI-AFL CL was 60 ms at CTI entry and less than or equal to 20 ms at septal CTI and proximal CS; AFL was terminated 1 cm inside CS, applying RF at a fragmented AP. Proximal CS appears to be involved in a substantial subset of typical AFL patients, in whom advanced age, fragmented CS APs, and the presence of right atrial scar are prevalent. Proximal CS might be considered as an un-"innocent by-stander," but able, in rare cases, to generate a second AFL circuit.

ECG Measurements to Emphasize Atrial Potentials Using Modified Limb Lead System

With the advancement in the field of Electrocardiology (ECG), the acquisition of electrical activity of the heart plays an important role in the diagnosis of various cardiovascular diseases. In general, this activity of conduction is acquired using Standard 12 Lead ECG system. Recently, a Modified Limb Lead system has been developed to study the atrial electrical activity for the diagnosis of atrial arrhythmias. The present study is to derive the normal limits of female subjects using Modified Limb Lead (MLL) system. This study was evaluated in 59 female subjects 19.52 ± 1 (Mean ± S.D) and is primarily involved to study atrial potentials with the use of precordial and modified limb lead position. In sinus rhythm female subjects, the P wave amplitude was 33.06 ± 21.18 µV and the Ta wave amplitude was 20.72 ± 18.16 µV. The P wave duration was 94.22 ± 10.64 ms, the Ta wave duration was 85.51 ± 17.49 ms. The results show that modifications in the limb electrode placement have significant effect on amplitudes and PR segment which may be of great importance for the assessment of atrial potentials.

Laser Catheter Modulation of the Sinus Node in the Treatment of Inappropriate Sinus Tachycardia: Experimental and Clinical Results.

Inappropriate sinus tachycardia (IST) is a rare type of arrhythmia that is currently difficult to treat successfully. The effects of laser catheter applications aimed at the sinus nodal area were tested experimentally and the technique was used for the treatment of IST. Continuous-wave, mapping-guided 1,064 nm neodymium-doped yttrium aluminum garnet laser applications at 15 W (9.5 W/mm2) per 15 seconds (142.5 J/mm2) and an irrigation flow of 30 mL/min were aimed at the sinus nodal area in five dogs (three applications each) and one human patient (two applications) by use of an 8-French open-irrigated electrode-laser mapping and ablation (ELMA) catheter provided with three miniature pin electrodes (0.5 mm × 4.0 mm) with interelectrode distances of 2.0 mm arranged symmetrically and radially around the endhole of the catheter tip. Laser application was aimed at the largest and earliest atrial potentials recorded in the focused local electrograms 30 ms to 45 ms prior to the onset of the P-wave in the surface lead electrocardiogram. Lesions were evaluated morphometrically. Holter monitoring in the patient was performed prior to and after treatment. During laser application in the dogs, sinus nodal potential amplitudes dwindled gradually from a mean of 42 mm ± 24 mm to 5.0 mm ± 3.0 mm and sinus cycle lengths lengthened from 452 ms ± 35 ms to 634 ms ± 35 ms (p < 0.0001 for both). In the patient, electrical potential amplitudes in the local electrograms dwindled from 41.0 mm to 5.0 mm and, in the Holter monitor, heart rate decreased from 109 bpm ± 29 bpm to 79 bpm ± 26 bpm (p < 0.0001). IST ablation was painless and without complications. During a follow-up of 4.9 years, the patient was asymptomatic and her heart rate and chronotropic competence remained normal. In conclusion, ablation of IST was achieved by substrate mapping-guided laser application while using the open-irrigated EMLA catheter RytmoLas (LasCor GmbH – Laser Medical Devices, Taufkirchen, Germany). However, this is a proof-of-concept study and further research, preferably in the form of multicenter study trials, is needed for confirmation of the results.

The influence of the electrodes spacing of a mapping catheter on the atrial voltage substrate map

BackgroundDetailed substrate mapping is important for catheter ablation. However, the influence of the electrode spacing of the mapping catheter on the substrate map has not been well clarified. The aim of this study was to investigate the influence of the electrode spacing of the mapping catheter on the voltage of the substrate map. MethodsProtocol 1: We recorded the local atrial potentials of the left atrium (LA) using the ablation catheter during sinus rhythm in six atrial fibrillation (AF) patients. The voltage of each atrial potential was compared between a close-bipolar (1–2 electrode) recording and wide-bipolar (1–4 electrode) recording. Protocol 2: Two voltage-maps of the LA were constructed separately using a 20-pole circular catheter and 10-pole circular catheter during sinus rhythm in 42 AF patients. The low voltage zone (LVZ) (<0.5mV) areas obtained by 2 voltage maps using the 10-pole and 20-pole circular catheters were compared. ResultsProtocol 1: The close-bipolar voltage of the local potentials was significantly smaller than that of the wide-bipolar voltages (0.76±0.39mV vs. 0.63±0.41mV, p<0.0001). Protocol 2: The size of the LVZ areas identified by the 10-pole and 20-pole catheters was 1.12±1.92cm2 (1.47±2.78%) and 8.30±7.80cm2 (8.83±8.32%), respectively (p<0.0001). ConclusionsThe voltage of the local atrial potential using the close-bipolar catheter was significantly smaller than that using the wide-bipolar catheter. Care should be given to the electrode spacing of mapping catheters when analyzing the voltage of the atrial myocardial potentials.

Does High-Intensity Endurance Training Increase the Risk of Atrial Fibrillation? A Longitudinal Study of Left Atrial Structure and Function.

Exercise mitigates many cardiovascular risk factors associated with atrial fibrillation. Endurance training has been associated with atrial structural changes which can increase the risk for atrial fibrillation. The dose of exercise training required for these changes is uncertain. We sought to evaluate the impact of exercise on left atrial (LA) mechanical and electrical function in healthy, sedentary, middle-aged adults. Sixty-one adults (52±5 years) were randomized to either 10 months of high-intensity exercise training or yoga. At baseline and post-training, all participants underwent maximal exercise stress testing to assess cardiorespiratory fitness, P-wave signal-averaged electrocardiography for filtered P-wave duration and atrial late potentials (root mean square voltage of the last 20 ms), and echocardiography for LA volume, left ventricular end-diastolic volume, and mitral inflow for assessment of LA active emptying. Post-training data were compared with 14 healthy age-matched Masters athletes. LA volume, Vo2 max, and left ventricular end-diastolic volume increased in the exercise group (15%, 17%, and 16%, respectively) with no change in control (P<0.0001). LA active emptying decreased post-exercise versus controls (5%; P=0.03). No significant changes in filtered P-wave duration or root mean square voltage of the last 20 ms occurred after exercise training. LA and left ventricular volumes remained below Masters athletes. The athletes had longer filtered P-wave duration but no difference in the frequency of atrial arrhythmia. Changes in LA structure, LA mechanical function, and left ventricular remodeling occurred after 10 months of exercise but without significant change in atrial electrical activity. A longer duration of training may be required to induce electrical changes thought to cause atrial fibrillation in middle-aged endurance athletes. URL: https://www.clinicaltrials.gov. Unique Identifier: NCT02039154.