High Right Atrium Research Articles

The impact of escape mapping for roof line completion during BOX isolation for atrial fibrillation

Abstract Background and Aim The creation of complete roof line (RL) is often challenging due to the presence of epicardial myocardial bundle or fat interposition. The disconnecting the septopulmonary bundle from the Buchmann bundle arrays requires for RL completion. Therefore, the conduction time to the left atrial appendage (LAA) and the high right atrium (HRA) potentials under left superior pulmonary vein pacing (LSPVp), so-called •escape mapping•, should be significantly prolonged after the creation of the transmural RL. This study investigates whether the changes conduction times from LSPVp to LAA and HRA (∆LSPVp-LAA and ∆LSPVp-HRA) between before and after the creation of the line as the assessment of bi-directional RL block. Methods 76 de-novo non-paroxysmal atrial fibrillation (nPAF) patients underwent BOXI strategy ablation. We initially intended single ring protocol BOXI for all patients. The activation times were measured at LAA and HRA under LSPV pacing at baseline and after application for the RL. Then we compared the change of activation time at LAA (∆LSPVp-LAA) and at HRA (∆LSPVp-HRA) between 2 groups; the group that completed BOXI with the first-pass roof line (fp-RL group) and the other group (Nfp-RL group). Results In 47 patients, the first-pass roof line was successfully obtained and in patients was done with additional application for gap(s) on the roof line to complete BOXI. There was a stepwise increase in mean ∆LSPVp-HRA not ∆LSPVp-LAA. Increased LA diameter, lower LVEF, and thinner LA wall were associated with the first-pass roof line. ∆LSPVp-HRA ≥33ms predict roof line block with high specificity and sensitivity. Conclusions Our findings suggest that the changes conduction times between LSPV and HRA during LSPV pacing help in the assessment of RL block.

Abstract 18514: A Simulation Study on the Inducibility of Atrial Fibrillation Drivers From Intra-Atrial Electrode Catheters Using Personalized Computational Models Based on LGE-MRI

Introduction: Although non-inducibility of atrial fibrillation (AF) drivers just after pulmonary vein isolation (PVI) with or without substrate ablation for persistent AF (PsAF) has been proposed as an acute outcome suggesting a successful long-term outcome, recent studies have found no association with long-term freedom from atrial tachyarrhythmias. It is unclear whether the latter finding is due to complete elimination of all AF drivers or the inadequacy of an AF induction test. Recently, patient-specific computer simulation based on late gadolinium enhancement (LGE)-MRI has been proposed to be useful for detecting rotors as PsAF drivers. Hypothesis: By investigating the accuracy of an induction test following PsAF ablation from the sites commonly used in clinical practice, particularly coronary sinus (CS), we might establish the promising method to confirm non-inducibility during ablation procedure. Methods: Thirty-five consecutive PsAF patients underwent LGE-MRI tests for fibrosis-based computational models. Rotors were induced by rapid pacing from 40 bi-atrial sites near fibrosis after PVI then ablated, repeated until obtaining non-inducibility of rotors. Each induced rotor was investigated for whether it was induced by pacing at lateral right atrium (RA), high RA or CS where electrode catheters were typically placed and used for induction test (Figure). Results: Except for 9 patients having poor LGE-MRI images or low fibrosis burden, 21 patients had a total of 136 locations capable of sustaining extra-PVI rotors. Of the total amount of rotors induced, 24% were induced by pacing at lateral RA, 11% at high RA and 45% at CS, respectively. The capture of all arrhythmogenic locations capable of sustaining rotors improved to 59% by performing induction test from all 3 pacing sites instead of a single one (p<0.01). Conclusions: Although CS is the reasonable pacing site for induction test, that from RA should be also conducted for the optimal rotor detection.

Abstract 17174: New Criteria for Block Across Anterior Mitral Line That Includes Bachmann’s Bundle in Patients With Scar Perimitral Flutter

Background: The recurrence rate of scar perimitral flutter (SMF) after anterior mitral line (AML) ablation remains high. Epicardial connections from high right atrium (HRA) to high lateral left atrium (HLA) including the Bachmann bundle (BB) plays a significant role in perimitral flutter recurrence. Hypothesis: We hypothesize that block across BB (BBB) during endocardial anterior line ablation reduces recurrence of atrial tachycardia (AT) and SMF. Methods: Patients undergoing left atrial ablation with SMF that were treated with AML were retrospectively enrolled. Pulmonary veins isolation and bidirectional AML block achieved in all patients. Baseline HRA-HLA, final HRA-HLA, and delta HRA-HLA intervals measured. Changes in HLA activation sequence determined. BBB identified when HRA-HLA interval increased with change in HLA activation sequence and confirmed with differential pacing. (Figure 1). The primary endpoint was recurrence of AT/SMF Results: We identified 101 patients, 51% comprised of women, with a mean age of 69. Patients who had AML without evidence of BBB were 48 compared to 53 patients who had AML with evidence of BBB. The mean baseline, final and delta HRA-LAA were 123 ± 42ms, 219 ± 45 ms and 96± 21 ms respectively in patients with BBB. After median follow up of 48 months, AT/SMF recurred in 43 % of patient without BBB vs 15 % in patient with BBB (p<0.008) (Figure 2). In patients with BBB, delta HRA-HLA >107ms discriminated between recurrence and no recurrence (p<0.023ms and 93% negative predictive value) Conclusion: During endocardial AML ablation for SMF, bidirectional block with evidence of BBB is associated with significant reduction in AT/SMF recurrence.

Blood Flow Simulation to Determine the Risk of Thrombosis in the Fontan Circulation: Comparison between Atriopulmonary and Total Cavopulmonary Connections

Three-dimensional computational fluid dynamics (CFD) simulations were performed in the anastomotic region of the Fontan route between the venae cava and pulmonary arteries to investigate the risk of thrombosis due to blood stasis in the Fontan circulation. The finite volume method based on the time-averaged continuity and Navier–Stokes equations combined with the k-ω SST turbulent model was used in the CFD simulations. Low shear rate (SR) and SR on the wall (WSR) of <10 s−1 were used as markers to assess blood stasis as a cause of blood coagulation. Simulated blood flow velocity and both SR and WSR were reduced in the right atrium (RA) as the cavity of a flow channel in the atriopulmonary connection (APC) Fontan model, whereas the values increased in the total cavopulmonary connection (TCPC) Fontan model, which has no cavity. The volume of SR <10 s−1 and wall surface area of WSR <10 s−1 were, respectively, 4.6–261.8 cm3 and 1.2–38.3 cm2 in the APC Fontan model, and 0.1–0.3 cm3 and 0.1–0.6 cm2 in the TCPC Fontan model. The SR and WSR increased in the APC model with a normal-sized RA and the TCPC model as the flow rate of blood from the inferior vena cava increased with exercise; however, the SR and WSR in the RA decreased in the APC model with a dilated RA owing to the development of a recirculating flow. These findings suggest that the APC Fontan has a higher risk of thrombosis due to blood stasis than the TCPC Fontan and a higher RA dilation is associated with a higher risk of thrombosis from a fluid mechanics perspective.

Tachycardia atrial cycle length equal to that during sinus rhythm: What is the mechanism?

A 64-year-old woman with frequent palpitations presented for atrial fibrillation radiofrequency catheter ablation (RFCA). She had not been administered any antiarrhythmic medication before admission to the hospital. After RFCA, a routine electrophysiological study was performed. Three catheters were positioned: a quadripolar catheter at the high right atrium (HRA), a quadripolar catheter at the His bundle region, and a decapolar catheter in the coronary sinus (CS) (CS 7-8 at the CS ostium). The baseline sinus cycle length was 628 milliseconds (ms), the atrial-His (AH) interval was 87 ms, and the His-ventricular (HV) interval was 52 ms. Antegrade atrioventricular (AV) nodal conduction showed decremental and dual pathways during atrial extrastimulus testing, but no tachycardia was induced. Retrograde ventriculoatrial (VA) conduction showed VA disassociation. Figure 1 shows a narrow QRS complex tachycardia with AV 1:1 conduction that was induced by two spontaneous ventricular extrasystoles. The corresponding intracardiac recording showed that the atrial cycle length oscillated between 627?30 ms (recorded by the HRA catheter) and 626?33 ms (recorded by the CS 7-8 catheter), which was approximately the same as that during sinus rhythm (SR) (Figure 2). How was the tachycardia induced and what is the mechanism of the tachycardia? This article is protected by copyright. All rights reserved.

423 Prevalence and prognostic significance of atrial arrhythmias in arrhythmogenic cardiomyopathy

Abstract Aims Limited data are available concerning atrial arrhythmias (AA) role in arrhythmogenic cardiomyopathy (AC). The aim of the present study was to assess the prevalence and incidence of AA in a large cohort of AC patients and to evaluate its association with clinical outcomes. Methods and results We retrospectively analysed 115 patients with definite diagnosis of ARVC, according to 2010 Task Force Criteria, enrolled in the Trieste Heart Muscle Disease Registry. Subjects were further classified into two phenotypic variants, based on ventricular involvement: right-dominant and biventricular form. Uni- and multivariable, extended Kaplan-Meier and cumulative incidence function analysis were performed, as appropriate, for the primary composite endpoint of death and heart transplant (HTx) and for the two distinct secondary endpoints of: (i) death, HTx and first heart failure (HF) hospitalization; (ii) first major ventricular arrhythmias (MVA). Mean age of patients at the time of enrollment was 39 ± 16 years and 80% were male. 73 patients (63%) had a right-dominant form, while 42 (37%) presented a biventricular involvement. AA occurred in the 26% of our study population at baseline or during a median follow-up of 214 months (IQR: 105–311), with a non-significant trend in higher cumulative incidence of AA in patients with biventricular form. At baseline, patients experiencing AA were older (44 ± 18 vs. 37 ± 15 years, P = 0.044) and had larger atrial dimensions, in particular of the right atrium (RA) (23, IQR: 19–27 vs. 18, IQR: 15–25 cm2, P < 0.007). AA emerged as independently associated to death/HTx (HR 2.68, 95% CI: 1.02–7.05, P = 0.046) along with NYHA class >2 (HR: 7.08, 95% CI: 2.50–20.1, P < 0.001) and RA area (HR: 1.05, 95% CI: 1.01–1.09, P = 0.011). Consistently, AA were also independently associated with the secondary endpoint of death/HTx/HF hospitalization (HR: 2.50, 95% CI: 1.06–5.88, P = 0.036), together with NYHA >2, the presence of biventricular involvement, higher RA and left atrium area. Finally, AA did not emerge as independently correlated to MVA during follow-up. Conclusions This observational long-term study suggests that AA were common in patients with AC and were independently associated with poor outcomes, mostly related to HF events. A prompt identification throughout the follow-up of AA appears relevant in improving the clinical management of AC patients.

Age- and Sex-Specific Changes in CMR Feature Tracking-Based Right Atrial and Ventricular Functional Parameters in Healthy Asians.

Cardiovascular magnetic resonance (CMR) is the reference standard for non-invasive assessment of right-sided heart function. Recent advances in CMR post-processing facilitate quantification of tricuspid annular (TA) dynamics and longitudinal strains of the right ventricle (RV) and right atrium (RA). We aimed to determine age- and sex-specific changes in CMR-derived TA dynamics, and RV and RA functional parameters in healthy Asian adults. We studied 360 healthy subjects aged 21–79 years, with 30 men and 30 women in each of the six age groups. Functional parameters of RV and RA were measured on standard four-chamber cine CMR using fast feature tracking: (1) TA peak velocities (systolic velocity S′, early diastolic velocity E′, late diastolic velocity A′) and TA plane systolic excursion (TAPSE); (2) RV global longitudinal strain (GLS) and strain rates; and (3) RA phasic longitudinal strains and strain rates. S′ and TAPSE exhibited negative correlations with age. RV GLS was significantly higher in females than in males but not associated with age in both sexes. Females had similar E′, lower A′, and higher E′/A′ ratios compared to males. Positive associations of E′ and E′/A′, and negative association of A′ with age were observed in both sexes. Females had higher RA reservoir and conduit strains compared to males. There were significantly negative and positive associations between RA conduit and booster strains, respectively, with age. Age- and sex-specific reference ranges were established, and associations revealed, for fast CMR feature tracking parameters of right heart function in a large normal Asian population.

V-A-A-V response to ventricular entrainment: What is the mechanism of this SVT?

A 61-year-old man presented with symptomatic, paroxysmal supraventricular tachycardia (SVT) at 210 bpm. His baseline 12-lead ECG in sinus rhythm was normal. He was brought to the electrophysiology laboratory where catheters were introduced into the right ventricular (RV) apex, His bundle region (His), high right atrium (HRA), and coronary sinus (CS). This article is protected by copyright. All rights reserved.

The Value of Voltage Histogram Analysis Derived Right Atrial Scar Burden in the Prediction of Left Atrial Scar Burden.

Introduction Growing evidence suggests that fibrotic changes can be observed in atrial fibrillation (AF) in both atria. Quantification of the scar burden during electroanatomical mapping might have important therapeutic and prognostic consequences. However, as the current invasive treatment of AF is focused on the left atrium (LA), the role of the right atrium (RA) is less well understood. We aimed to characterize the clinical determinates of the RA low-voltage burden and its relation to the LA scaring. Methods We have included 36 patients who underwent catheter ablation for AF in a prospective observational study. In addition to LA mapping and ablation, high-density RA bipolar voltage maps (HD-EAM) were also reconstructed. The extent of the diseased RA tissue (≤0.5 mV) was quantified using the voltage histogram analysis tool (CARTO®3, Biosense Webster). Results The percentage of RA diseased tissue burden was significantly higher in patients with a CHA2DS2-VASc score ≥ 2 (p = 0.0305), higher indexed LA volume on the CTA scan and on the HD‐EAM (p = 0.0223 and p = 0.0064, respectively), or higher indexed RA volume on the HD‐EAM (p = 0.0026). High RA diseased tissue burden predicted the presence of high LA diseased tissue burden (OR = 7.1, CI (95%): 1.3–38.9, p = 0.0145), and there was a significant correlation of the same (r = 0.6461, p < 0.0001). Conclusions Determining the extent of the right atrial low-voltage burden might give useful clinical information. According to our results, the diseased tissue burden correlates well between the two atria: the right atrium mirrors the left atrium.

Simple differential entrainment screens ablation strategy for slow-fast atrioventricular nodal reentrant tachycardia.

Ablation of slow-fast atrioventricular nodal reentrant tachycardia (S/F-AVNRT) is occasionally refractory. We hypothesized that the site of ablation for curing S/F-AVNRT can be screened by simple differential atrial entrainment pacing (EP) from the high right atrium (HRA) and proximal coronary sinus (prox-CS). We enrolled 43 patients with S/F-AVNRT who underwent successful differential atrial EP followed by successful ablation of slow pathway (SP) using step-wise approach, and compared the atrio-His (A-H) interval at the recording of His bundle immediately after EP from the HRA [A-H(HRA)], with the interval between atrial deflection at the prox-CS and His bundle electrogram after EP at an identical cycle length from the prox-CS [A-H (prox-CS)]. A typical A-H(CS) shorter than A-H(HRA), consistent with typical SP conduction, was observed in 39 patients (91%), and an atypical A-H(HRA) shorter than A-H(CS) was observed in 4 patients (9%). Successful ablation was obtained at the posteroseptum/midseptum in 32/7 patients with typical responses but only at the midseptum in all 4 patients with atypical responses (P=.0027). The atypical responses predicted a necessity for ablation at the midseptum, with positive and negative predictive values of 100% and 82%, respectively. The mechanism of an atypical response remains unclear but may involve an anatomical variation of Koch's triangle and/or the participation of a variant of the SP, including the superior SP, over which retrograde conduction was observed more frequently in patients with atypical responses (P=.0013). Differential atrial EP predicts the ablation site for successfully curing S/F-AVNRT.

Elongation of the high right atrium to coronary sinus conduction time predicts the recurrence of atrial fibrillation after radiofrequency catheter ablation

BackgroundThe impact of intra-atrial conduction delay on the recurrence of atrial tachyarrhythmia after radio frequency catheter ablation (RFCA) has not been fully elucidated. MethodsWe retrospectively analyzed 155 AF patients who were sinus rhythm at the start of RFCA. The conduction time from the onset of the earliest atrial electrogram at the high right atrium (HRA) to the end of the latest electrogram at the coronary sinus (CS) during sinus rhythm was defined as HRA-CS conduction time. Pulmonary vein isolation (PVI) was performed followed by linear roof lesion and complex fractionated atrial electrogram (CFAE) ablation until AF termination. We evaluated atrial tachyarrhythmia recurrence 12 months after RFCA. ResultsThe follow-up data were available for 148 patients. The recurrence of atrial tachyarrhythmia was noted in 28 (18.9%) patients. Atrial tachyarrhythmia recurrence patients had longer HRA-CS conduction times (151.3 ± 22.1 ms vs 160.1 ± 32.6 ms, p = .017). The patients were divided into the long or short HRA-CS conduction time group. The Kaplan–Meier analysis revealed that the long HRA-CS conduction time group held a higher risk of atrial tachyarrhythmia recurrence (log-rank test, p = .019). The multivariable Cox hazard analysis revealed that a long HRA-CS conduction time was a significant risk factor for the recurrence of atrial tachyarrhythmia, despite a long AF duration, persistent AF, and larger left atrial diameter (LAD) were not statistically significant. ConclusionsThe HRA-CS conduction time was the primary influencing factor that predicted the recurrence of atrial tachyarrhythmia after catheter ablation.

Electrophysiological Measurement of Rat Atrial Epicardium Using a Novel Stereotaxic Apparatus.

Flexible, in vivo maneuverable electrophysiology mapping techniques are not available in rat models. A novel cardiac stereotactic electrophysiology epicardial mapping system (CREAMS) allows for various measurements, including: (1) recording unipolar electrograms at multiple sites; (2) positioning of mapped sites and precision testing (Distance between the two "centers" = 297 ± 54 μm, n = 15); (3) evaluation of electrophysiology in an in vivo Sprague-Dawley rat model with high-frequency stimulation (HFS)-induced Atrial fibrillation (AF) at high right atrium (HRA) sites. We found that of the right atrium dispersion of effective refractory period (P < 0.05) and the window of vulnerability (P < 0.01) were significantly increased (P < 0.05) after HRA HFS. CREAMS has the potential for convenient electrophysiology assessment in a rat AF model through stereo-positioning, and flexible operating manipulation.

A work flow to build and validate patient specific left atrium electrophysiology models from catheter measurements.

Biophysical models of the atrium provide a physically constrained framework for describing the current state of an atrium and allow predictions of how that atrium will respond to therapy. We propose a work flow to simulate patient specific electrophysiological heterogeneity from clinical data and validate the resulting biophysical models. In 7 patients, we recorded the atrial anatomy with an electroanatomical mapping system (St Jude Velocity); we then applied an S1-S2 electrical stimulation protocol from the coronary sinus (CS) and the high right atrium (HRA) whilst recording the activation patterns using a PentaRay catheter with 10 bipolar electrodes at 12 ± 2 sites across the atrium. Using only the activation times measured with a PentaRay catheter and caused by a stimulus applied in the CS with a remote catheter we fitted the four parameters for a modified Mitchell-Schaeffer model and the tissue conductivity to the recorded local conduction velocity restitution curve and estimated local effective refractory period. Model parameters were then interpolated across each atrium. The fitted model recapitulated the S1-S2 activation times for CS pacing giving a correlation ranging between 0.81 and 0.98. The model was validated by comparing simulated activations times with the independently recorded HRA pacing S1-S2 activation times, giving a correlation ranging between 0.65 and 0.96. The resulting work flow provides the first validated cohort of models that capture clinically measured patient specific electrophysiological heterogeneity.

Wavefront direction and cycle length affect left atrial electrogram amplitude

BackgroundThe relationship between atrial electrogram (EGM) characteristics in atrial fibrillation (AF) and those in sinus rhythm (SR) are generally unknown. The activation rate and direction may affect EGM characteristics. We examined characteristics of left atrial (LA) EGMs obtained during pacing from different sites. MethodsThe study included 10 patients undergoing pulmonary vein isolation for AF. Atrial EGMs were recorded from a 64-pole basket catheter placed in the LA, and bipolar EGM amplitudes from the distal electrode pair (1–2) and proximal electrode pair (6–7) from 8 splines were averaged. The high right atrium (HRA), proximal coronary sinus (CSp), and distal coronary sinus (CSd) were paced at 600 ms and 300 ms. ResultsWhen the LA voltage at SR was ≥1.5 mV, bipolar voltages of the HRA were greater than those of the CSp, which were greater than those of the CSd, regardless of the pacing cycle length. The shorter pacing cycle length resulted in a reduction of the LA EGM voltage at sites of SR voltage ≥1.5 mV, but no significant difference was seen at sites where the SR EGM amplitude was between >0.5 and <1.5 mV. No significant differences were seen in intra-basket conduction times between pacing cycle lengths of 600 ms and 300 ms at any pacing site. ConclusionThe rate and direction-dependent reduction of the amplitude of atrial EGMs may explain, in part, the voltage discordance during SR and AF.

Association of Rate-Dependent Conduction Block Between Eccentric Coronary Sinus to Left Atrial Connections With Inducible Atrial Fibrillation and Flutter.

We sought to describe the prevalence and variability of coronary sinus (CS) and left atrial (LA) myocardium connections, their susceptibility to rate-dependent conduction block, and association with atrial fibrillation (AF) and flutter induction. The study cohort included 30 consecutive AF patients (age 63.3±10.5 years, 63% male). Multipolar catheters were positioned in the CS, high right atrium (HRA), and LA parallel to and near the CS. Trains of 10 pacing stimuli were delivered during sinus rhythm from each of the following sites: CS proximal (CSp), CS distal (CSd), LA septum (LAs), lateral LA (LAl), and HRA, at the following cycle lengths: 1000, 500, 400, 300, and 250 ms, while recording from the other catheters. With the CS 9 to 10 bipole just inside the CS ostium, CS-LA connections were observed in 100% at CS 9 to 10, 30% at CS 7 to 8, 23% at CS 5 to 6, 23% at CS 3 to 4, and 97% at CS 1 to 2. Eighteen patients (60%) had AF/atrial flutter induced. Rate-dependent conduction block of a CS-LA connection at cycle length of ≥250 ms was present in 17 (94%) of those with versus none of those without AF/atrial flutter induction (P<0.001). Rate-dependent eccentric CS-LA conduction block is associated with AF/atrial flutter induction in patients with drug-refractory AF undergoing ablation. The presence of dual muscular CS-LA connections, coupled with unidirectional block in one limb, seems to serve as a substrate for single or multiple reentry beats, and arrhythmia induction.

The effect of atrial pacing site on electrophysiological properties of the atrioventricular junction and induction of atrioventricular nodal reentry in patients with typical atrioventricular nodal reentrant tachycardia.

Clinical studies in humans have shown the site of atrial stimulation to influence atrioventricular (AV) conduction times and refractory periods, the demonstration of dual AV nodal (AVN) pathways, and induction of AVN reentry. These studies often found conflicting results. Moreover, among enrolled patients a minority of them were found to have AVN reentrant tachycardia (AVNRT). The purpose of this study was to investigate the effect of right and left atrial pacing on the electrophysiological properties of the AV junction in the typical AVNRT population. Ninety-two consecutive patients with typical AVNRT were included. Atrial pacing was performed from the high right atrium (HRA) and the left atrium via the proximal coronary sinus (CS). Stimulation from either the HRA or the CS could result in dual AVN physiology and AVNRT. No site-dependent differences in the ease of induction of dual AVN pathways with variability of initiation from either site were found. However, AVNRT was easier to induce from the HRA. With CS pacing the leftward but not the rightward AVN approaches were the entry point to the AV node because of significantly shorter AH conduction times compared to HRA pacing. Conduction over the leftward AVN extensions could initiate the tachycardia with significantly shorter critical AH interval compared to conduction over the rightward AVN extensions; however, the AH interval during AVNRT and its cycle length were not significantly different. Rightward and leftward AVN extensions are regular features of the AV node. Their different electrophysiological properties lead to variation in the demonstration of discontinuous AVN conduction and AVNRT during right and left atrial pacing. Despite the observation that the left AVN extensions could compose the entry point to the reentrant circuit, there is no evidence that they constitute the critical component of sustained typical AVNRT.

The utility of atrial pacing for identifying the electrical breakthrough sites between the left atrium and pulmonary veins

BackgroundCircumferential pulmonary vein (PV) isolation for atrial fibrillation (AF) is occasionally difficult to achieve because electrical breakthrough sites (EBSs) between the left atrium (LA) and PVs cannot be identified during ablation especially in the carina regions. MethodsThe left PVs (Lt.PVs) of 60 AF patients and the right PVs (Rt.PVs) of 37 patients undergoing PV isolation were studied. When PV isolation was not achieved after the initial circumferential PV isolation, atrial pacing was repeatedly performed from the distal coronary sinus (CSd) and high right atrium (HRA), and the time interval from the stimulus to the earliest PV potential (stimulus-PV interval) was measured using circular mapping catheters at each PV until PV isolation was achieved. When PV isolation was achieved via local Radiofrequency (RF) deliveries, those regions were diagnosed as final EBSs. We classified the final EBSs into six segments for each PV (anterior and posterior PV walls of the roof, carina, and bottom) and investigated the relationship between the final EBSs and stimulus-PV intervals. ResultsFor Lt.PVs, the stimulus-PV intervals during CSd pacing were significantly shorter than during HRA pacing at the Lt.PV anterior carina and bottom (90±28ms vs. 125±26ms, P<0.001 and 84±20ms vs. 148±24ms, P=0.028, respectively), but there was no significant difference in the Lt.PV roof and any posterior segments. For Rt.PVs, the stimulus-PV interval from both pacing sites exhibited no significant difference between either segment. ConclusionsThis pacing method may help to identify whether EBSs are located in the anterior Lt.PVs. Improved recognition of EBSs through pacing from different sites would be helpful for achieving PV isolation.

Assessment of intracardiac flow and vorticity in the right heart of patients after repair of tetralogy of Fallot by flow-sensitive 4D MRI.

To comprehensively and quantitatively analyse flow and vorticity in the right heart of patients after repair of tetralogy of Fallot (rTOF) compared with healthy volunteers. Time-resolved flow-sensitive 4D MRI was acquired in 24 rTOF patients and 12 volunteers. Qualitative flow evaluation was based on consensus reading of two observers. Quantitative analysis included segmentation of the right atrium (RA) and ventricle (RV) in a four-chamber view to extract volumes and regional haemodynamic information for computation of regional mean and peak vorticity. Right heart intra-atrial, intraventricular and outflow tract flow patterns differed considerably between rTOF patients and volunteers. Peak RA and mean RV vorticity was significantly higher in patients (p = 0.02/0.05). Significant negative correlations were found between patients' maximum and mean RV and RA vorticity and ventricular volumes (p < 0.05). The main pulmonary artery (MPA) regurgitant flow was associated with higher RA and RV vorticity, which was significant for RA maximum and RV mean vorticity (p = 0.01/0.03). The calculation of vorticity based on 4D flow data is an alternative approach to assess intracardiac flow changes in rTOF patients compared with qualitative flow visualization. Alterations in intracardiac vorticity could be relevant with regard to the development of RV dilation and impaired function. • 4D flow MRI with vorticity calculation enables a novel approach to assess intracardiac flow. • Significantly higher intracardiac vorticity occurred in patients after repair of tetralogy of Fallot. • Regurgitant flow in the main pulmonary artery is associated with higher right heart vorticity.

Electrophysiological and Electroanatomical Mapping of the Right Atrium in Persistent Atrial Fibrillation: Relation to Collagen Turnover.

Atrial fibrillation (AF) is associated with abnormal atrial substrate. We investigated whether patients with persistent lone AF and patients with persistent AF and nonischemic dilated cardiomyopathy (NIDCM) exhibit any differences in electrophysiological and electroanatomical properties of right atrium (RA) and collagen turnover. We also investigated the relationship between mean RA bipolar voltage and collagen turnover. Ten patients with a history of persistent lone AF and eight patients with a history of persistent AF and NIDCM were studied. Sinus node recovery times (SNRTs) and effective refractory periods (ERPs) at 600 ms, 500 ms, and 400 ms from the high (HLRA) and low (LLRA) lateral RA, proximal coronary sinus (pCS), and right atrial appendage (RAA) were evaluated, and RA electroanatomic mapping was created. Serum N-terminal propeptide of collagen type I (PINP), cross-linked C-terminal telopeptide of collagen type I (CTx), matrix metalloproteinase-1 (MMP-1), and tissue inhibitor of matrix metalloproteinases (TIMP-1) were measured as markers of collagen synthesis and degradation. No differences were found in SNRTs, ERPs from the HLRA, LLRA at 600 ms, pCS and RAA, mean RA bipolar voltage, serum PINP, CTx, MMP-1, and TIMP-1 between the two groups. In persistent lone AF, serum levels of TIMP-1 were related with mean HLRA and HPRA bipolar voltage. Persistent AF patients with or without NIDCM, demonstrate similar changes in electrophysiological and electroanatomical properties of the RA, as well as similar structural changes. Moreover, serum markers of collagen synthesis are correlated with bipolar voltage in specific regions of RA in persistent lone AF.

Principal component analysis of atrial fibrillation: Inclusion of posterior ECG leads does not improve correlation with left atrial activity

BackgroundLead V1 is routinely analysed due to its large amplitude AF waveform. V1 correlates strongly with right atrial activity but only moderately with left atrial activity. Posterior lead V9 correlates strongest with left atrial activity. Aims(1) To establish whether surface dominant AF frequency (DAF) calculated using principal component analysis (PCA) of a modified 12-lead ECG (including posterior leads) has a stronger correlation with left atrial activity compared to the standard ECG. (2) To assess the contribution of individual ECG leads to the AF principal component in both ECG configurations. MethodsPatients were assigned to modified or standard ECG groups. In the modified ECG, posterior leads V8 and V9 replaced V4 and V6. AF waveform was extracted from one-minute surface ECG recordings using PCA. Surface DAF was correlated with intracardiac DAF from the high right atrium (HRA), coronary sinus (CS) and pulmonary veins (PVs). Results96 patients were studied. Surface DAF from the modified ECG did not have a stronger correlation with left atrial activity compared to the standard ECG. Both ECG configurations correlated strongly with HRA, CS and right PVs but only moderately with left PVs. V1 contributed most to the AF principal component in both ECG configurations.