Earliest Activation Time Research Articles

A novel endocardial activation–derived predictor for focal paraseptal atrial tachycardias: Evidence from a multicenter cohort study

BackgroundThe electrocardiogram-based algorithm for predicting paraseptal atrial tachycardia (PSAT) is limited by the significant overlaps in P-wave morphology originating from various paraseptal sites. ObjectivesThe goals of this study were to investigate the endocardial activation characteristics of PSAT and to seek an endocardial activation–derived predictor for the ablation site. MethodsForty-four patients [11 men (25%); mean age 62.6 ± 14.7 years] with PSAT ablation in 4 tertiary medical centers were assigned to 3 groups according to the ablation site: right atrial (RA) para-Hisian region (group 1, n = 10), noncoronary cusp (NCC) (group 2, n = 13), and left atrial (LA) paraseptal area (group 3, n = 21). Multiple-chamber activation mapping was performed guided by a 3-dimensional navigation system. The discrepancies in the earliest activation time between 2 of 3 chambers (ΔRA-LA, ΔRA-NCC, and ΔLA-NCC) were calculated in each group and used for pairwise comparisons. ResultsThere was a significant difference in ΔRA-LA, ΔRA-NCC, and ΔLA-NCC among the 3 groups. ΔRA-LA was the only parameter that could consistently predict the ablation site of PSAT with good accuracy (area under the curve 1.000, sensitivity 100% and specificity 100%, and cutoff value 7 ms for predicting right para-Hisian or NCC ablation; area under the curve 0.974, sensitivity 92.3% and specificity 95.2%, and cutoff value −4 ms for predicting NCC or left paraseptal ablation). Based on 2 cutoff values, a 2-step algorithm was developed to predict the ablation site of PSAT with a positive predictive value of 95.4% and a negative predictive value of 97.0%. ConclusionΔRA-LA is a useful endocardial activation–derived parameter for predicting the successful ablation site of PSAT.

Characteristics of Local Endograms at the Site of Successful Arrhythmia Suppression During Activation Mapping of Idiopathic Ventricular Arrhythmias Using 3D Navigation

A topical issue is the determination of the optimal values of activation time of local endograms (LE) and bipolar signal morphology during ablation in patients with idiopathic ventricular arrhythmias (VA) at the site of successful suppression, and the influence of 3D navigation on these values.
 The aim. To study earliest activation time (EAT) and LE morphology in the area of successful suppression during ablation of idiopathic VA using 3D navigation.
 Materials and methods. Analysis of the results of ablation in 57 patients with idiopathic VA was made. The patients were divided into two groups. Group I included 30 (52.6%) patients in whom mapping was performed using 3D navigation (EnSite Velocity Cardiac Mapping System). Group II included 27 (47.4%) patients who were mapped using conventional methods.
 In group I, extrasystole was found in 20 (66.7%) patients, while ventricular tachycardia was observed in 10 (33.3%) patients. In group II, extrasystole was revealed in 16 (59.3%) patients, and ventricular tachycardia in 11 (40.7%) patients.
 Group I included 21 (70%) patients with right ventricular localization of arrhythmia and 9 (30%) patients with left ventricular localization. Meanwhile, group II included 17 (63%) patients with a focus in the right ventricle and 10 (33%) patients with that in the left ventricle.
 The morphology of the LE was evaluated according to criteria such as polarity (positive or negative) and degree of signal fragmentation (monomorphic or fragmented). Polarity was determined by the initial direction of the signal during the first 10 ms, regardless of further changes in the endogram. The signal was considered fragmented if there were three or more polarity changes.
 Results. In group I, EAT of LE was -38.0±7.0 ms, while in group II it was -38.0±8.5 ms. No difference was found between the studied groups (p=0.834).
 Among all patients in both groups, the average value of EAT of LE at the site of successful arrhythmia elimination was -37.0±8.5 ms. In 92.9% cases EAT of LE was -30 ms or earlier. Only in four (7.1%) patients it was possible to achieve suppression of the arrhythmia with EAT of LE not earlier than -30 ms, while in all these cases the focus was always localized in the right ventricle. The minimum value of EAT of LE at the site of successful suppression of arrhythmia was -27 ms.
 The dominant morphology at the site of successful suppression among the patients in both groups, regardless of the type of mapping, was positive polarity of endogram.
 Conclusions. Regardless of the mapping method, in the site of successful idiopathic VA suppression LE must precede QRS by at least 27 ms.

Genome-Wide Characterization of TAZ Binding Sites in Mammary Epithelial Cells.

The transcriptional co-activator with PDZ binding motif (TAZ) is a key effector of the Hippo signaling pathway. We and others previously reported that high expression levels of TAZ are positively associated with decreased survival rates and shorter times to relapse in basal-like breast cancer (BLBC) patients. The oncogenic activity of TAZ involves the regulation of diverse signal transduction pathways that direct processes such as cell proliferation, migration, and resistance to apoptosis, albeit through poorly characterized gene expression programs. Here, using a tet-inducible system in mammary epithelial MCF10A cells, we have characterized the TAZ-regulated transcription program using RNA sequencing in a temporal and spatial manner. We further identified global TAZ binding sites at different TAZ activation time points by chromatin immunoprecipitation (ChIP) sequencing analysis. We found that the vast majority of TAZ was rapidly localized in enhancer regions at the early TAZ activation time point and then gradually spread to promoter regions. TAZ bound to enhancer regions following a switch in potential TEAD and FOSL2 transcription factor motifs. Furthermore, the ATAC sequencing analysis indicated that TAZ activation led to chromatin structural alterations. Together, our results have revealed the landscape of genome-wide TAZ binding sites and may lead to improvements in the current understanding of how TAZ regulates the gene expression program that contributes to the development of breast cancer.

PO-04-201 A CASE OF PVC OCCURRING RIGHT BUNDLE BRANCH BLOCK AND PR INTERVAL PROLONGED DURING ETHANOL ABLATION VIA THE CORONARY VENOUS SYSTEM

Ethanol ablation via the coronary venous system (CVS) has been reported to be effective and safe as a novel therapy for ventricular arrhythmias, especially for the epicardial and intramural origin sites. Previous studies reported no heart block complications during retrograde coronary venous ethanol ablation, neither atrioventricular block (AVB) nor other types of conductive system block. N/A A 67-year-old female with symptomatic and drug-refractory premature ventricular contractions (PVCs) was admitted for ablation therapy. The PVC burden was 31.7%. The 12-lead ECG showed a PVC with LBBB, inferior axis with a precordial transition in lead V3, and QS pattern in lead I. The QRS duration of PVC was 143ms. The Q-wave ratio of lead aVL/aVR was 1.47. Endocardial mapping was performed using a 3.5mm open-irrigated-tip catheter (ThermoCool, Biosense Webster, CA, USA). The earliest activation time was -8ms and -10ms pre-QRS at the septal aspect of right ventricular outflow tract (RVOT) and the left coronary sinus (LCC), respectively (Fig 1A). Ablation with 35-40W, 45-50°C was attempted but no response. We considered it might be an intramural origin site. The CVS angiography was performed and the ablation catheter was positioned in LCC for reference (Fig 1B). The earliest activation time (-27ms) was mapped in a septal branch of the anterior interventricular vein (AIV) with a 3.3F quadripolar catheter and local pace mapping matched well. Selective angiography confirmed the quadripolar catheter was in the septal branch rather than AIV (Fig 1C-D). A balloon was used to deliver ethanal and prevent its backflow to AIV. 1ml 96% ethanol was infused slowly (Fig 1E-F). PVC was eliminated immediately as soon as the ethanol infusion. But we noticed the PR interval prolonged from 178 to 190ms. More ethanol was injected carefully to consolidate the effect but we stopped infusion after a total of 2.5ml ethanol because the ECG showed complete RBBB and PR interval prolonged further to 202ms. RBBB and I° AVB were persistent during the whole hospitalization for 3 days. However, at 1-month follow-up, the QRS morphology returned to normal and the PR interval shortened to 172ms (Fig 1G). 24-hour Holter showed no recurrence. Ethanol ablation via the CVS also might induce heart block complications due to the adjacent anatomical position with the conductive system, even though it might be reversible. Operators should be cognizant of the potential risk.

Catheter ablation of idiopathic outflow tract ventricular arrhythmias with low intraprocedural burden guided by pace mapping.

BackgroundThere are limited data comparing ablation outcomes in patients with low intraprocedural burden of ventricular arrhythmias (VA) undergoing a pace mapping (PM)–guided strategy vs those with high burden guided by standard activation mapping strategy (non-PM).ObjectiveWe sought to determine if catheter ablation–guided by PM of low-intraprocedural-burden idiopathic outflow tract VA would be noninferior compared to non-PM-guided ablation.MethodsOutcomes of catheter ablation of idiopathic outflow tract VA in 22 patients with a low burden of intraprocedural VA using PM-guided ablation were compared to 44 patients with a high burden of intraprocedural VA undergoing ablation using standard techniques.ResultsSixty-six patients were included (age 46.5 ± 14.8 years; 68% female, left ventricular ejection fraction 59% ± 5%). Within the PM group, 24-hour preprocedure premature ventricular complex (PVC) burden was 9.5% (interquartile range [IQR] 4%–13.8%), number of pace maps 33.6 ± 18.5, surface area of ≥95% pace map correlation 1.9 ± 1.2 cm2, with best pace map correlation 96% (IQR 92%–97%). Within the non-PM group, 24-hour preprocedure PVC burden was 13.5% (IQR 6.6%–30%), earliest activation time -33.7 ± 9.9 ms. Procedural duration, general anesthesia administration, fluoroscopy dose, and complications were all comparable. Following final procedure, 24-hour VA burden (PM 0% [IQR 0–2.4%] vs non-PM 0% [IQR 0–4.2%], P = .98), along with VA-free survival at 6-month follow-up (PM 77% vs non-PM 71%, P = .77), were both comparable.ConclusionIn patients with low intraprocedural burden of outflow tract VA, PM-guided catheter ablation can accurately identify the VA site of origin, leading to outcomes comparable to those achieved with standard ablation techniques.

Earliest activation time is a good predictor of successful ablation of idiopathic outflow tract ventricular arrhythmias

BackgroundIn idiopathic outflow tract ventricular arrhythmias (OT‐VAs), identifying the site with the earliest activation time (EAT) using activation mapping is critical to eliminating the arrhythmogenic focus. However, the optimal EAT for predicting successful radiofrequency catheter ablation (RFCA) has not been established.HypothesisTo evaluate the association between EAT and successful RFCA in idiopathic OT‐VAs and to determine the optimal cut‐off value of EAT for successful ablation.MethodsWe retrospectively analyzed patients undergoing RFCA for idiopathic OT‐VAs at a single center from January 2015 to December 2019.ResultsAcute procedural success was achieved in 168 patients (87.0%). Among these patients, 158 patients (81.9%) were classified in the clinical success group according to the recurrence of clinical VAs during median (Q1, Q3) follow‐up (330 days [182, 808]). EAT was significantly earlier in the clinical success group compared with the recurrence (p = .006) and initial failure (p < .0001) groups. The optimal EAT cut‐off value predicting clinical success was −30 ms in the right ventricular outflow tract (RVOT) with 77.4% sensitivity and 96.4% specificity. In all cases of successful ablation in the left ventricular outflow tract (LVOT), EAT in the RVOT was not earlier than −29 ms.ConclusionsEAT in patients with successful catheter ablation was significantly earlier than that in patients with recurrence and initial failure. EAT earlier than −30 ms could be used as a key predictor of successful catheter ablation as well as an indicator of the need to shift focus from the RVOT to the LVOT.

Multipolar mapping for catheter ablation of premature ventricular complexes originating from papillary muscles in the structurally normal heart: a case series

BackgroundPrevious studies on radiofrequency catheter ablation of premature ventricular complexes (PVCs) arising from the left ventricle (LV) papillary muscles (PM) show a modest procedural success rate with higher recurrence rate. Our study sought to explore the utility of using a multipolar mapping with a steerable linear duodecapolar catheter for ablating the PM PVCs.MethodsDetailed endocardial multipolar mapping was performed using a steerable linear duodecapolar catheter in 6 consecutive PM PVCs patients with structurally normal heart. The clinical features and procedural data as well as success rate were analysed.ResultsLV endocardial electroanatomic mapping was performed in all patients via a retrograde aortic approach using a duodecapolar mapping catheter. All patients displayed a PVC burden with 16.2 ± 5.4%. Duodecapolar catheter mapping demonstrated highly efficiency with an average procedure time (95.8 ± 7.4 min) and fluoroscopy time (14.2 ± 1.5 min). The mean number of ablation applications points was 6.8 ± 1.9 with an average overall ablation duration of 6.1 ± 3.0 min. The values of earliest activation time during mapping using duodecapolar catheter were 37.8 ± 7.2 ms. All patients demonstrated acute successful ablation, and the PVC burden in all patients after an average follow-up of 8.5 ± 2.0 months was only 0.7%. There were no complications during the procedures and after follow-up.ConclusionsMapping and ablation of PM PVCs using a duodecapolar catheter facilitated the identification of earliest activation potentials and pace mapping, and demonstrated a high success rate during follow-up.

Automatic annotation of local activation time was improved in idiopathic right ventricular outflow tract ventricular arrhythmia by novel electrogram "Lumipoint" algorithm.

Precise automatic annotation of local activation time (LAT) is crucial for rapid high-density activation mapping in arrhythmia. However, it is still challenging in voltage-transitional areas where local low-amplitude near-field potentials are often obscured by large far-field potentials. The aim of this study was to explore the viability and validity of automatic identification of the earliest activation (EA) in idiopathic right ventricular outflow tract ventricular arrhythmias (RVOT VAs) using a novel Lumipoint algorithm. Twenty-seven patients with RVOT VAs were mapped with Rhythmia mapping system. Lumipoint algorithms were applied to reannotate the initial activation regions retrospectively. The results showed that LATs were reannotated in 35.0 ± 11.4% points in the initial activation area from bipolar activation breakout time (BBO) to the its 40ms earlier timepoint. The automatically determined bipolar earliest activation time after Lumipoint reannotation (BEAT-lu: - 111.26 ± 12.13ms) was significantly earlier than that before (BEAT: - 108.67 ± 12.25ms, P = 0.000). Compared with manually corrected earliest activation time (EAT), the difference between EAT and BEAT-lu (DEAT-BEAT-lu: 6 (2-7) ms) was significantly smaller than that between EAT and BEAT (DEAT-BEAT/DEAT-UEA: 7 (4-11) ms, P = 0.000). The incidence of EAT and BEAT-lu being the same site was significantly higher than that between EAT and BEAT (48.15% vs 18.52%, P = 0.021). RVOT VAs often originate from voltage-transitional zone, and automatic annotation of LAT usually located at later high-amplitude far-field potential. Lumipoint algorithms could improve the accuracy of LAT automatic annotation, and it was plausible to ablate RVOT VAs just according to the automatically annotated BEAS-lu.

On the efficiency and accuracy of the single equivalent moving dipole method to identify sites of cardiac electrical activation.

We have proposed an algorithm to guide radiofrequency catheter ablation procedures. This algorithm employs the single equivalent moving dipole (SEMD) to model cardiac electrical activity. The aim of this study is to investigate the optimal time instant during the cardiac cycle as well as the number of beats needed to accurately estimate the location of a pacing site. We have evaluated this algorithm by pacing the ventricular epicardial surface and inversely estimating the locations of pacing electrodes from the recorded body surface potentials. Two pacing electrode arrays were sutured on the right and left ventricular epicardial surfaces in swine. The hearts were paced by the electrodes sequentially at multiple rates (120-220bpm), and body surface ECG signals from 64 leads were recorded for the SEMD estimation. We evaluated the combined error of the estimated interelectrode distance and SEMD direction at each time instant during the cardiac cycle, and found the error was minimum when the normalized root mean square (RMS n ) value of body surface ECG signals reached 15% of its maximum value. The beat-to-beat variation of the SEMD locations was significantly reduced (p<0.001) when estimated at 15% RMS n compared to the earliest activation time (EAT). In addition, the 5-95% interval of the estimated interelectrode distance error decreased exponentially as the number of beats used to estimate a median beat increased. When the number of beats was 4 or larger, the 5-95% interval was smaller than 3.5mm (the diameter of a commonly used catheter). In conclusion, the optimal time for the SEMD estimation is at 15% of RMS n , and at that time instant a median beat estimated from 4 beats is associated with a beat-to-beat variability of the SEMD location that is appropriate for catheter ablation procedures.

Focal atrial tachycardia surrounding the anterior septum: strategy for mapping and catheter ablation.

Background—Focal atrial tachycardias (ATs) surrounding the anterior atrial septum (AAS) have been successfully ablated from the right atrial septum (RAS), the aortic cusps, and the aortic mitral junction. However, the strategy for mapping and ablation of AAS-ATs has not been well defined.Methods and Results—Of 227 consecutive patients with AT, 47 (20.7%; mean age, 56.3±11.6 years) with AAS-ATs were studied; among them, initial ablation was successful at RAS in only 5 of 14 patients and at noncoronary cusp (NCC) in 28 of 33 patients. In 45 of the 47 patients, the 46 of 48 AAS-ATs were eliminated at RAS in 8 patients, NCC in 35 patients (earliest activation time at NCC was later than that at RAS by 5–10 ms in 6 patients), and aortic mitral junction in 3 patients (all with negative P wave in lead aVL and positive P wave in the inferior leads), including 1 patient whose 2 ATs were eliminated separately from the NCC and the aortic mitral junction.Conclusions—Most of the ATs surrounding the AAS can be eliminated from within the NCC, which is usually the preferential ablation site. Ablation at the RAS and aortic mitral junction should be considered when supported by P-wave morphologies on surface ECG and results of activation mapping and ablation.

Impact of Hurricane Sandy on hospital emergency and dialysis services: a retrospective survey.

Hurricane Sandy forced closures of many free-standing dialysis centers in New York City in 2012. Hemodialysis (HD) patients therefore sought dialysis treatments from nearby hospitals. The surge capacity of hospital dialysis services was the rate-limiting step for streamlining the emergency department flow of HD patients. The aim of this study was to determine the extent of the HD patients surge and to explore difficulties encountered by hospitals in Brooklyn, New York (USA) due to Hurricane Sandy. A retrospective survey on hospital dialysis services was conducted by interviewing dialysis unit managers, focusing on the influx of HD patients from closed dialysis centers to hospitals, coping strategies these hospitals used, and difficulties encountered. In total, 347 HD patients presented to 15 Brooklyn hospitals for dialysis. The number of transient HD patients peaked two days after landfall and gradually decreased over a week. Hospital dialysis services reported issues with lack of dialysis documentation from transient dialysis patients (92.3%), staff shortage (50%), staff transportation (71.4%), and communication with other agencies (53.3%). Linear regression showed that factors significantly associated with enhanced surge capacity were the size of inpatient dialysis unit (P = .040), having affiliated outpatient dialysis centers (P = .032), using extra dialysis machines (P = .014), and having extra workforce (P = .007). Early emergency plan activation (P = .289) and shortening treatment time (P = .118) did not impact the surge capacity significantly in this study. These findings provide potential improvement options for receiving hospitals dialysis units to prepare for future events.

Characteristics of Unsuccessful Catheter Ablation of Ventricular Arrhythmia

This study was to identify the electrophysiologic characteristics of unsuccessful catheter ablation (CA) of ventricular arrhythmias (VAs). Methods: Out of 302 patients undergoing CA of VAs, 43 consecutive patients (14.2%, 43±4 years) who attempted but failed to eliminate VAs with the first CA (US group). US group was compared with successful CA group (S group) to assess predictors to affect unsuccessful ablation. Results: US group included 8 patients underwent unsuccessful CA and 35 patients underwent repeated CA due to arrhythmia recurrence. Presenting VA was ventricular tachycardia (VT) in 24 patients (55.8%) but premature ventricular complex in only 13 patients (30.2%). VT was more common in US group (55.8%) than that of S group (39.0%, P=0.03). The ejection fraction of the left ventricle (LV) was lower in US group (38.0±7.2%) than in S group (43.7±.9%, P=0.02). The earliest activation time (EAT) prior to QRS onset in US group (29.8±7.8 ms) was later than S group (37.4±8.4 ms, P=0.04). There was a significant difference in VAs origin from-right ventricular outflow tract (RVOT) (41.8% in US group vs. 60.2% in S group, P=0.02). There were no significant differences in QRS width during VAs between two groups. Conclusions: A VT as presenting VAs, the severity of LV dysfunction, later EAT and non-RVOT origin were associated with unsuccessful CA, in whom repeated CA was often required.

Non-linear dimensionality reduction of signaling networks

BackgroundSystems wide modeling and analysis of signaling networks is essential for understanding complex cellular behaviors, such as the biphasic responses to different combinations of cytokines and growth factors. For example, tumor necrosis factor (TNF) can act as a proapoptotic or prosurvival factor depending on its concentration, the current state of signaling network and the presence of other cytokines. To understand combinatorial regulation in such systems, new computational approaches are required that can take into account non-linear interactions in signaling networks and provide tools for clustering, visualization and predictive modeling.ResultsHere we extended and applied an unsupervised non-linear dimensionality reduction approach, Isomap, to find clusters of similar treatment conditions in two cell signaling networks: (I) apoptosis signaling network in human epithelial cancer cells treated with different combinations of TNF, epidermal growth factor (EGF) and insulin and (II) combination of signal transduction pathways stimulated by 21 different ligands based on AfCS double ligand screen data. For the analysis of the apoptosis signaling network we used the Cytokine compendium dataset where activity and concentration of 19 intracellular signaling molecules were measured to characterise apoptotic response to TNF, EGF and insulin. By projecting the original 19-dimensional space of intracellular signals into a low-dimensional space, Isomap was able to reconstruct clusters corresponding to different cytokine treatments that were identified with graph-based clustering. In comparison, Principal Component Analysis (PCA) and Partial Least Squares – Discriminant analysis (PLS-DA) were unable to find biologically meaningful clusters. We also showed that by using Isomap components for supervised classification with k-nearest neighbor (k-NN) and quadratic discriminant analysis (QDA), apoptosis intensity can be predicted for different combinations of TNF, EGF and insulin. Prediction accuracy was highest when early activation time points in the apoptosis signaling network were used to predict apoptosis rates at later time points. Extended Isomap also outperformed PCA on the AfCS double ligand screen data. Isomap identified more functionally coherent clusters than PCA and captured more information in the first two-components. The Isomap projection performs slightly worse when more signaling networks are analyzed; suggesting that the mapping function between cues and responses becomes increasingly non-linear when large signaling pathways are considered.ConclusionWe developed and applied extended Isomap approach for the analysis of cell signaling networks. Potential biological applications of this method include characterization, visualization and clustering of different treatment conditions (i.e. low and high doses of TNF) in terms of changes in intracellular signaling they induce.

Predictors for Successful Ablation of Right- and Left-Sided Idiopathic Ventricular Tachycardia

This study reports on predictors for successful radiofrequency (RF) ablation of idiopathic ventricular tachycardia (VT) in 48 patients—35 with right ventricular (RV) outflow tract and 13 with left ventricular VT. In RV outflow tract idiopathic VT, RF ablation was successful in 29 of 35 patients (83%). The following information allowed differentiation between patients with and without a successful RF ablation: >1 induced VT morphology (0 vs 3); presence of delta wave-like beginning of the QRS (2 vs 3) and ≥11 of 12 leads showing a “match” between the clinical VT and the pacemap (28 vs 1). Endocardial activation times were not different between both groups (−15 ± 18 vs −4 ± 5 ms). In left ventricle idiopathic VT, RF ablation was successful in 12 of 13 patients (92%). In patients who underwent successful ablation, 1 VT morphology was induced and no delta wave-like beginning of the QRS was present; a correlation between clinical VT and the pacemap ≥11 of 12 leads was found and the endocardial activation time preceded the QRS (range of −5 to −58 ms [mean −30 ± 14]). Purkinje activity was observed in 5 of 7 patients with an idiopathic VT originating from the inferoposterior region but not from the inferoapical region of the left ventricle. Four patients (14%) with RV outflow tract idiopathic VT had recurrence during a mean follow-up of 2 to 50 months (mean 30 ± 12). Thus, (1) in RV outflow tract idiopathic VT a good pacemap was more important than an early endocardial activation time; (2) an optimal pacemap as well as an early endocardial activation time were important predictors for successful ablation of the left ventricle idiopathic VT; (3) Purkinje activity was recorded in VTs arising in the inferoposterior region of the left ventricle; and (4) factors for unsuccessful ablation for idiopathic VT were >1 induced VT morphology, a delta wave-like beginning of the QRS, and a VT/pacemap correlation <11 of 12 leads. Idiopathic VT can be successfully ablated with both immediate and long-term success.

Localization and radiofrequency catheter ablation of left-sided accessory pathways during atrial fibrillation Feasibility and electrogram criteria for identification of appropriate target sites

Objectives. The purpose of the present study was to assess the feasibility of and electrophysiologic criteria for successful radio-frequency catheter ablation of left-sided accessory pathways during atrial fibrillation in patients with Wolff-Parkinson-White syndrome.Background. The onset of recurrent or sustained atrial fibrillation can complicate or significantly prolong accessory pathway catheter ablation procedures.Methods. We studied 19 consecutive patients (mean age [±SD] 44 ± 16 years) with Wolff-Parkinson-White syndrome who had ongoing atrial fibrillation with rapid anterograde conduction over the accessory pathway (mean ventricular rate [±SD] 173 ± 26 beats/min, range 130 to 220) at the beginning of the localization procedure during radiofrequency catheter ablation. Localization and ablation of the accessory pathway were performed with a 7F deflectable catheter (4-mm tip) that was placed underneath the mitral valve annulus. The electrophysiologic criteria from unipolar and bipolar local electrograms were compared for successful (n = 18) and unseccessful (n = 39) sites.Results. The accessory pathways were localized in the left posteroseptal (n = 6), posterior (n = 1), posterolateral (n = 7) and lateral (n = 5) regions and successfully ablated during atrial fibrillation in 18 (95%) of 19 patients with a mean of 3 ± 2 radiofrequency pulses (range 1 to 8, median 2). Presence of an accessory pathway potential (94% vs. 44%), early activation time of the ventricular electrogram (−3.2 ± 9.2 vs.−15.3 ± 12.6 ms) and recording of atrial activation (88% vs. 61%) from the ablation catheter were helpful in identifying successful sites (p < 0.001, p < 0.001 and p < 0.05, respectively, compared with unsuccessful sites). In addition, the ventricular activation time in relation to the intrinsic deflection of the unipolar electrogram was significantly earlier at successful than unsuccessful sites (18.1 ± 4.8 vs. 24.4 ± 6.6 ms, p < 0.01). A QS complex on the unipolar electrogram was observed at 96% of successful sites and at 94% of unsuccessful sites (p = 0.74). Multivariate logistic regression analysis revealed that the presence of an accessory pathway potential (p < 0.002) and early ventricular activation time in relation to the onset of the QRS complex (p < 0.001) were independent predictors of ablation success.Conclusions. Localization and radiofrequency catheter ablation of left-sided accessory pathways is possible in patients with sustained atrial fibrillation and rapid anterograde conduction over the accessory pathway during the ablation procedure. The electrophysiologic criteria described here can be used to reliably identify successful sites for radiofrequency ablation.

Early and late potentials in postinfarction patients.

Injury within the myocardium may cause disturbances of the intraventricular conduction and may be manifested by altered spectrum of the QRS complex. The purpose of this report is to indicate the existence of microvolt early waves appearing at the beginning of the QRS complex in some postinfarction patients with low ejection fraction. The method used incorporated the high resolution ECG recording, where the "pyramid" electrode location was applied. Results indicated a relationship between high frequency potentials, QRS duration time, and ejection fraction, as well as dependence between ventricular tachycardia/fibrillation (VT/VF) occurrence and early and/or late ventricular activity. In patients with secondary VT/VF where early and late potentials were found, the ejection fraction (EF) was the lowest (26 +/- 15%). Early waves appeared more often in patients with secondary VT/VF (30%) compared with those with primary VT/VF (8%). In patients without VT/VF and without myocardial infarction (MI) early potentials were not remarked. In those patients late potentials also appeared less often. It could be concluded that existence of early potentials, late activity, and significant prolonged total ventricular activation time is associated with wide dispersion and nonuniform delay of the electrical activity within the myocardium as well as with serious lowering of the ejection fraction. Therefore, existence of early waves seems to be a significant diagnostic factor for the poor hemodynamic condition as well as a serious warning for the recurrent late ventricular tachycardia/fibrillation.

Sinus node shift after the Senning procedure compared with the mustard procedure for transposition of the great arteries

To investigate the nature of the dominant intrinsic cardiac pacemaker activity after the Senning procedure, endocardial mapping of the systemic venous atrium was accomplished a mean of 13 months after operation in 10 patients, aged 22 ± 6 months. Multiple endocardial sites were measured to find the earliest atrial electrical activity timed back from the QRS complex. These data were compared with data from endocardial mapping performed in 6 patients late after the Mustard procedure. In 8 of 10 patients who had undergone the Senning procedure, the earliest activation time, corresponding by definition to the origin of the intrinsic pacemaker, was located in the inferior medial portion of the superior limb of the systemic venous atrium. In the other 2 patients who had undergone the Senning procedure, the earliest activity was in the high superior limb of the baffle at its junction with the superior vena cava. In contrast, the earliest activity in all patients who underwent the Mustard operation was at the junction of the superior vena cava and the superior limb of the systemic venous atrium. In response to programmed extrastimulation, the electrophysiologic behavior of the intrinsic pacemaker in the Senning group was abnormal compared with known normal sinus node (SN) data in only 3 of 10 patients, whereas all patients in the Mustard group had SN dysfunction. Abnormal SN function was noted in both patients in the Senning group, in whom a shift in the position of the earliest endocardial activation point was not seen. The anatomic shift in the position of the earliest pacemaker activity observed after the Senning procedure, but not after the Mustard operation, results from a physical shift in the position of the SN inherent to the atrial free-wall infolding aspect of the Senning operation.