Distal Bipole Research Articles

Identifying Origin of Nonpulmonary VeinTriggers Using 2 Stationary LinearDecapolar Catheters: A Novel Algorithm.

Targeting nonpulmonary vein triggers (NPVTs) of atrial fibrillation (AF) after pulmonary vein isolation can be challenging. NPVTs are often single ectopic beats with a surface P-wave obscured by a QRS or T-wave. The goal of this study was to construct an algorithm to regionalize the site of origin of NPVTs using only intracardiac bipolar electrograms from 2 linear decapolar catheters positioned in the posterolateral right atrium (along the crista terminalis with the distal bipole pair in the superior vena cava) and in the proximal coronary sinus (CS). After pulmonary vein isolation in 42 patients with AF, pacing from 15 typical anatomic NPVT sites was conducted. For each pacing site, the electrogram activation sequence was analyzed from the CS catheter (simultaneous/chevron/inverse chevron/distal-proximal/proximal-distal) and activation time (ie, CSCTAT) between the earliest electrograms from the 2 decapolar catheters was measured referencing the earliest CS electrogram; a negative CSCTAT value indicates the crista terminalis catheter electrogram was earlier, and a positive CSCTAT value indicates the CS catheter electrogram was earlier. A regionalization algorithm with high predictive value was defined and tested in a validation cohort with AF NPVTs localized with electroanatomic mapping. In the study patient cohort (71% male; 43% with persistent AF, 52% with left atrial dilation), the algorithm grouped with high precision (positive predictive value 81%-99%, specificity 94%-100%, and sensitivity 30%-94%) the 15 distinct pacing sites into 9 clinically useful regions. Algorithm testing in a 98 patient validation cohort showed predictive accuracy of 91%. An algorithm defined by the activation sequence and timing of electrograms from 2 linear multipolar catheters provided accurate regionalization of AF NPVTs to guide focused detailed mapping.

Impact of filter configurations on bipolar EGMs: An optimal filter setting for identifying VT substrates.

The impact of filtering on bipolar electrograms (EGMs) has not been systematically examined. We tried to clarify the optimal filter configuration for ventricular tachycardia(VT)ablation. Fifteen patients with VT were included. Eight different filter configurations were prospectively created for the distal bipoles of the ablation catheter: 1.0-250, 10-250, 100-250, 30-50, 30-100, 30-250, 30-500,and 30-1000 Hz. Pre-ablation stable EGMs with good contact (contact force > 10 g) were analyzed. Baseline fluctuation, baseline noise, bipolar peak-to-peak voltage, and presence of local abnormal ventricular activity (LAVA) were compared between different filter configurations. In total, 2276 EGMs with multiple bipolar configurations in 246 sites in scar and border areas were analyzed. Baseline fluctuation was only observed in the high-pass filter of (HPF) ≤ 10 Hz (p < .001). Noise level was lowest at 30-50 Hz (0.018 [0.012-0.029] mV), increased as the low-pass filter (LPF) extended, and was highest at 30-1000 Hz (0.047 [0.041-0.061] mV) (p < .001). Conversely, the HPF did not affect the noise level at ≤30 Hz. As the HPF extended to 100 Hz, bipolar voltages significantly decreased (p < .001), but were not affected when the LPF was extended to ≥100 Hz. LAVAs were most frequently detected at 30-250 Hz (207/246; 84.2%) and 30-500 Hz (208/246; 84.6%), followed by 30-1000 Hz (205/246;83.3%), but frequently missed at LPF ≤ 100 Hz or HPF ≤ 10 Hz (p < .001). A 50-Hz notch-filter reduced the bipolar voltage by 43.9% and LAVA-detection by 34.5% (p < .0001). Bipolar EGMs are strongly affected by filter settings in scar/border areas. In all, 30-250or 30-500 Hz may be the best configuration, minimizing the baseline fluctuation, baseline noise, and detecting LAVAs. Not applying the 50-Hz notch filter may be beneficial to avoid missing VTsubstrate.

Short RP tachycardia with Concentric atrial activation: What is the mechanism?

A 50-year old man with a structurally normal heart presented with recurrent palpitations for six months. This was in spite of a recent radiofrequency ablation at another center for a presumed diagnosis of atrio-ventricular nodal reentrant tachycardia (AVNRT). Interestingly, his first radiofrequency ablation for a tachyarrhythmia was over a decade ago, but records were unavailable. The 12 lead Electrocardiogram (ECG) revealed a short RP tachycardia at rate of 170 bpm. There was no preexcitation during sinus rhythm. Baseline intervals were normal during the ensuing electrophysiology study (EPS). The catheter positions with the annotations His (His bundle), CS (coronary sinus; proximal bipole 9-10 at CS ostium and distal bipole 1-2) and RV (right ventricle apex) are self-explanatory. A regular narrow complex tachycardia with rate related right bundle branch block (CL 280-340 ms, shortest VA 90 ms, and AH 165 ms) was reproducibly induced with a single atrial extra stimulus test (AEST) (Figure 1a). The response to maneuvers performed during tachycardia are denoted: i.e. right ventricular overdrive pacing (VOP) (Figure 1b), His refractory ventricular extra stimulus (HRVES) from the RV (Figure 1c), as well the left ventricular (LV) apex via the radiofrequency ablation catheter (RF 1-2, Figure 1d). What can be deciphered as the mechanism of this tachycardia? This article is protected by copyright. All rights reserved.

Abstract 13253: Regionalizing Non-Pulmonary Vein Triggers for Atrial Fibrillation Using Timing and Activation Pattern of Intracardiac Electrograms From Two Linear Decapolar Catheters

Introduction Targeting non-pulmonary vein triggers (NPVTs) after pulmonary vein isolation (PVI) reduces atrial fibrillation (AF) recurrence. However, NPVTs are often single atrial ectopic beats with surface P wave obscured, making regionalization a challenge. We aimed to construct an algorithm to regionalize the site of origin of NPVTs using exclusively intracardiac electrograms from two standardly positioned linear decapolar catheters positioned 1) in the postero-lateral right atrium, along crista terminalis (CT) with distal bipole pair extending into SVC, and 2) in the coronary sinus (CS), with proximal bipole pair at CS ostium. Methods In 42 patients with AF, after PVI, we paced at 15 sites where NPVTs commonly arise (Figure 1). For each pacing site we analyzed activation sequence of the CS catheter electrogram (simultaneous/chevron/inverse chevron/distal-proximal/proximal-distal) and the timing (CSCT time) between the earliest electrograms from the two decapolar catheters. Negative CSCT time indicates CT catheter electrogram is earliest, positive indicates CS catheter electrogram is earliest (Figure 2, lower right). Results In this patient cohort (71% male, 57% persistent AF, 52% left atrial dilation), our algorithm was able to group the 15 pacing sites, into 7 clinically useful and distinct regions with high precision (positive predictive value range 81-99%, Figure 2). Conclusions An algorithm defined by the activation sequence and timing of electrograms from two linear multipolar catheters allows for accurate regionalization of NPVTs. This may be used to expedite identification of a region of interest to guide further focused detailed mapping of AF NPVTs.

Novel multi-site, multi-point biventricular pacing configuration: acute haemodynamic benefit

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by the research grant of the AZV (Ministry of Health of the Czech Republic) Background Biventricular pacing (BVP) using multiple left ventricular (LV) sites may augment the hemodynamic effect of cardiac resynchronisation therapy (CRT) by engaging a greater mass of the myocardium. Purpose To evaluate the acute hemodynamic effect of a novel multi-site, multi-point BVP configuration. Methods The study investigated 18 patients with idiopathic dilated cardiomyopathy and left bundle-branch block during implantation of a BVP device (age: 59 ± 14 years, female gender: 7 [39%], LVEF: 27 ± 6%, native QRS: 171 ± 16 ms). Conventional leads were placed in the right atrium (RA) and ventricle (RV), one quadripolar LV lead (Quartet, Abbott, Abbott Park, IL, USA) was positioned in the posterolateral and another one in lateral or anterolateral coronary vein. Individual bipoles of all leads were connected through a splitter to separate external cardiac stimulators. Hemodynamics was evaluated using a micromanometer-tipped catheter (Micro-Cath, Millar, Tx, USA) located in the LV during RA pacing above sinus rate and five atrio-ventricular sequential pacing configurations at the same rate: 1.) RA+RV, 2.) RA + RV + distal bipole of the LV lead with greater dP/dT („conventional BVP"), 3.) RA + RV + distal and proximal bipoles of the LV lead with greater dP/dT („single-lead multi-point BVP"), 4.) RA + RV + distal bipoles of both LV leads („two-lead multi-site BVP"), and 5.) sequentional pacing RA + RV + all bipoles of both LV leads interconnected to a mesh („maximum BVP"). Results Compared to RA pacing, LV dP/dT was significantly greater during all BVP pacing configurations (RA pacing: 1940 ± 507 mmHg/s vs. conventional BVP: 2431 ± 855 mmHg/s, single-lead multi-point BVP: 2539 ± 740 mmHg/s, two-lead multisite BVP: 2517 ± 836 mmHg/s, and "maximum BVP": 2685 ± 893 mmHg/s, all p&amp;lt;0.001, Figure 1), but not during RA-RV pacing (2014 ± 721 mmHg/s, p=0.12). In addition, dP/dT was significantly greater during "maximum BVP" compared to conventional BVP (p=0.05). Conclusion Compared to RA pacing and conventional BVP, the greatest increase in LV contractility was achieved with a novel multi-site, multi-point "maximum BVP" configuration. These preliminary findings provide a rationale for designing new approaches to CRT.

B-PO02-176 ENTRAINMENT OF IDIOPATHIC LEFT VENTRICULAR TACHYCARDIA FROM LEFT VENTRICULAR SEPTUM INDICATED NEGATIVE PARTICIPATION OF DISTAL LEFT POSTERIOR FASCICLE

As a macro-reentrant tachycardia, the circuit of idiopathic left ventricular tachycardia (ILVT) is mainly described by activation mapping. Evidence from entrainment in left ventricle (LV) is limited. To investigate the reentrant circuit ILVT by entrainment at LV septum. In 4 patients with ILVT from left posterior fascicle (LPF) area, a decapolar catheter placed at LV septum was used to delineate activation pattern of Purkinje potentials (PP) during tachycardia. Entrainment was performed using multiple pairs of electrodes where PPs were recorded. The tachycardia cycle length (TCL), QRS pattern, electrogram sequences and post pacing intervals (PPI) were analyzed. PPIs were measured from both stimulus to return PP (PPI1) and ventricular electrogram (PPI2), respectively. P1 potentials was recorded in 3/4 patients. 18 bursts of entrainment were performed. QRS during overdrive was always slightly different from tachycardia QRS in morphology, but sequence of P2 suggested concealed fusion when entraining earliest P2, or P1-P2 fusion site(n=4). PPI1-TCL here was significantly shorter than PPI2-TCL (6±6.7ms vs. 33.8±6.7ms P<0.01) and PPI1-TCL at the next distal bipole (n=4, 6±6.7ms vs. 36.3±15.6ms, P<0.01), although their P2 timing difference were all less than 15ms. Ablation at sites with shortest PPI1 eliminated all ILVTs. Overdrive from earliest P2 site during ILVT demonstrated entrainment with concealed fusion in fascicles. PPI was significantly longer at the sites distal to earliest P2, indicating distal LPF was the "inner bystander" of the circuit, which may solely involve Purkinje network in the vicinity of LPF.

Electrical delays in quadripolar leads with cardiac resynchronization therapy.

Pacing at sites of late intraventricular activation (QLV) or long interventricular conduction (right ventricle [RV]-left ventricular [LV]) have been associated with improved cardiac resynchronization therapy (CRT) outcomes. Quadripolar leads improve CRT outcomes by allowing for electrical repositioning to optimize pacing sites. However, little is known regarding the effect of such repositioning on electrical delay. Determine the relationship between different electrical bipoles from a quadripolar lead and measures of electrical delay. Forty-six patients underwent CRT with a quadripolar lead. The RV-LV and QLV intervals were measured for both the proximal and distal bipoles and the difference (Δ) between bipoles for each measure were calculated. Multivariate analyses were performed to identify predictors of electrical delays. This was a typical CRT population with a mean age of 65 years and ejection fraction of 27%, with left bundle branch block(LBBB) present in 70%. The regression model for ΔQLV was significant (p = .05), with both gender (p = .008) and LBBB status (p = .020) significant predictors. The overall regression model for ΔRV-LV was not significant. ΔQLV and ΔRV-LV were significant among LBBB patients. Among non-LBBB, only ΔRV-LV was significant (mean: 7.2 ms, p = .006). ΔRV-LV versus ΔQLV were strongly correlated in LBBB (R2 = .92) but not non-LBBB (R2 = .06). In LBBB, ΔRV-LV and ΔQLV are closely correlated suggesting that the proximal bipole and thus basal LV pacing sites should be selected when feasible. Greater variation in activation pattern is present in non-LBBB, so pacing sites should be individualized.

Utility of Mapping Signals to Improve Precision of Atrioventricular Node Ablation

Atrioventricular node (AVN) ablation is effective for rate control in atrial fibrillation. This may require multiple radiofrequency applications to achieve complete atrioventricular block (CAB). In this retrospective study, we tested the hypothesis that mapping the AVN utilizing electrograms (EGMs) on both proximal and distal bipoles of the mapping catheter may improve the likelihood of CAB. Lesion characteristics and EGM components on the proximal and distal bipoles of the ablation catheter in first-time AVN ablation procedures were analyzed. Outcomes of each lesion, including presence of CAB, acute recurrence of AVN conduction, new-onset right bundle branch block (RBBB), and junctional escape rhythm, were analyzed. Multivariate binary logistic regression analysis was performed to identify EGM characteristics that independently predicted the outcomes of interest. Lesions with these EGM characteristics were then identified and their outcomes compared with the whole cohort. A total of 441 ablation lesions were analyzed. EGM characteristics that independently predicted outcomes were the presence of His and atrial EGMs on the distal bipole and the absence of ventricular EGM on the proximal bipole. Among the 25 lesions with all these characteristics, 18 (72%) resulted in CAB compared to the overall cohort rate of 38% (P = 0.001). There was no new-onset RBBB. The likelihood of acute recurrent AVN conduction and junctional escape rhythm were similar. Combining proximal and distal bipole EGM characteristics of the ablation catheter can improve the accuracy of AVN localization during AVN ablation and avoid right bundle branch injury.

Restoration of Sinus Rhythm by Incarceration, not Elimination, of Focal Atrial Tachycardia in Left Atrial Substrate Post Atrial Fibrillation Ablation

While diseased regions of the atrial body commonly behave as a substrate maintaining atrial fibrillation (AF), these areas can uncommonly behave as trigger foci for atrial tachycardia (AT),1 particularly after previous ablation. Unlike venous triggers, the goal of ablation for these focal ATs is normally elimination of the tachycardia source, rather than complete isolation. We present a case of a difficult to ablate post–AF-ablation AT from the anterior left atrium (LA), in which sinus rhythm was restored by incarcerating the ongoing AT within a small, isolated region of LA myocardium. A 67-year-old man who underwent pulmonary vein isolation, electrogram-based LA ablation, and roof, left mitral and cavotricuspid isthmus ablation for permanent AF in 2002 and repeat ablation of recurrent paroxysmal AF in 2009 (details unavailable), was referred for a third ablation procedure for rate-controlled incessant AT (Figure 1A). Figure 1B shows intracardiac recordings on decapolar catheter in the coronary sinus and 3.5-mm externally irrigated tip ablation catheter in the LA during baseline AT (cycle length, 308 ms). Activation and entrainment mapping2 established the diagnosis of focal source AT arising from the ostium of the left atrial appendage (LAA) where ablation led to cycle length variation of >25% (range, 276 to 402 ms) – unstable AT (Figure 1C). Focal ablation at another site with substantial temporal gradient between the proximal and distal bipoles of the ablation catheter …

The influence of fat thickness on the human epicardial bipolar electrogram characteristics: measurements on patients undergoing open-heart surgery

Reference values exist for endocardial but not for epicardial (EPI) substrate mapping in cases of cardiomyopathy-associated ventricular tachycardia. We sought to establish such values for EPI electrogram voltage, including areas with overlying fat. Ten patients (six males) undergoing cardiac surgery were studied. After opening the pericardium, the distal bipole of an electrophysiology catheter was placed tangential to the EPI surface to obtain an electrogram recording. The bipole was tangentially rotated 90 degrees and the higher of the two amplitudes (mV) was taken as the local amplitude. Recordings were taken from normal left and right ventricular myocardium (n = 26 data points each), over thick (> or = 0.5 cm) fat at both ventricular bases (n = 16) and thin (<0.5 cm) fat at the mid-ventricular level (n = 32). A total of 100 recordings (mean 10/patient) were analysed. Four patients underwent valvular surgery, three bypass surgery, and three combined procedures. Mean age was 61.7 +/- 10.4 years and mean left ventricular ejection fraction was 46 +/- 12%. Electrogram amplitude was inversely related to EPI fat thickness. Over thick fat, 31% of recordings were <0.5 mV. Human EPI electrogram amplitude varies by ventricular chamber and significantly by EPI fat thickness. A cut-off of 0.5 mV to define 'scar' will include normal areas with thick overlying fat. EPI substrate maps should include data on EPI fat thickness for higher specificity.

Supraventricular tachycardia: What is the mechanism?

A 32-year-old woman presented with recurrent episodes of palpitations and documented supraventricular tachycardia (SVT). Five years earlier, she had had similar symptoms and reportedly underwent successful ablation of a manifest left lateral accessory pathway. An electrophysiology study was performed. Quadripolar electrophysiology catheters were placed in the high right atrium, His bundle, and right ventricular (RV) apex. A decapolar catheter (2-8-2 mm spacing) was placed in the coronary sinus with the proximal bipole at the coronary sinus ostium, and the distal bipole was located posterolaterally.

Catheter Ablation for Atrial Fibrillation

▪ Abstract Atrial fibrillation is frequently disabling and resistant to antiarrhythmic drugs. Curative treatment by catheter-based ablation has been shown to be feasible either by achieving long linear lesions, mainly in the left atrium, or by targeting the initiating focus, most frequently in the pulmonary veins. This paper reviews the different ablation approaches, their results, potential complications, and relative merits.