Proximal Coronary Sinus Research Articles

Early coronary artery atherosclerosis in humans is associated with attenuated coronary retention of klotho

Abstract Background Vascular aging is a key feature of cardiovascular disease. α-klotho (klotho) is a protein inversely associated with aging and may contribute to vascular repair. Lower levels of systemic klotho have been identified in humans with features of early and advanced coronary atherosclerosis. It remains unknown if circulating klotho is present within human coronary circulation and whether cardiovascular klotho retention correlates with atherosclerosis. Purpose The current study aimed to assess the presence of klotho within coronary circulation compared to systemic circulation and hypothesized that net coronary klotho retention is attenuated in patients with early age-related features of coronary artery disease (CAD). Methods A total of 42 patients that underwent clinically indicated coronary angiogram for chest pain that had no obstructive CAD underwent intravascular ultrasound (IVUS) assessment were retrospectively examined. Virtual histology assessed coronary plaque characteristics. Blood samples simultaneously collected from the proximal aorta and coronary sinus were used for klotho detection using enzyme-linked immunosorbent assay. The net gradient of klotho across cardiovascular circulation was calculated by multiplying the arteriovenous klotho gradient by basal coronary blood flow. A net positive gradient indicated less cardiovascular klotho retention; a net negative gradient indicated greater cardiovascular klotho retention. Results Overall, participants were age 54±10 years old and 76% were female. There were overall higher levels of klotho within the coronary sinus (median 0.49 ng/mL [0.15; 1.69]) compared to systemic circulation (median 0.30 ng/mL [0.16; 1.14]). Participant groups were determined by those with positive (n = 20) or negative (n = 22) cardiovascular retention of klotho. Both groups were similar in age (56 ±2 vs. 51 ±2 years old, p = 0.080), gender (72% vs. 80% female, p = 0.580), and had similar occurrences of traditional cardiovascular comorbidities. Those with less cardiovascular klotho retention in the coronary vascular bed had significantly greater degree of non-obstructive coronary artery plaque (Gensini score 3.5 vs. 0, p < 0.001) and had higher percent plaque burden (46% [35; 53] vs. 34% [28; 46], p = 0.044) than those with greater cardiovascular klotho retention. Conclusions Patients with early coronary atherosclerosis may be characterized by attenuated retention of klotho within coronary circulation. Moreover, humans appear to have higher circulating klotho in coronary circulation than in systemic circulation. The current study may support a role for mechanism or potential therapeutic target for klotho in coronary atherosclerosis in humans.

CT-scan-guided-irrigated trans-catheter ablation of epicardial accessory pathways in the coronary sinus: safety and feasibility in pediatric patients.

The most common site of epicardial APs is posterior-septal, and ablation from the coronary sinus (CS) or its main tributaries is needed. However, particularly in children, it can carry a considerable risk of complications, such as coronary artery (CA) injury, CS damage, and perforation. This study aims to assess the efficacy and safety of computed tomography (CT)-scan-guided-irrigated trans-catheter (TC) ablation of epicardial APs through the CS in children. Twenty-four children (19 males; mean age 13.8 ± 2.6) with posterior-septal and left posterior epicardial APs who underwent an endocavitary electrophysiological study (EPS) and TC ablation from the CS were enrolled in this study. All patients underwent a CT scan to visualize the CS and its branches and their proximity to the CAs before the ablation. Clinical, electrophysiological and follow-up data were collected. Acute success rate was 87.5% (21 out of 24 procedures). No complications occurred. In 16 (66.7%) patients, the ablation site was detected at the proximal CS, in two (8.3%) patients in the mid-proximal CS and in six (25%) in the middle cardiac vein (MCV). Ablation was achieved using an irrigated radiofrequency (RF) catheter in all patients and without the use of fluoroscopy in 20 patients (83.3%). Over a median follow-up of 15.1months (IQR 2.5-32.3), no recurrences or complications occurred. Epicardial posterior-septal and left posterior APs, in the area of CS or MCV, can be definitively eliminated in most children using CT-scan-guided electro-anatomical mapping and transvenous irrigated RF ablation.

Coronary sinus signal amplitude: A predictor of the atrial substrate and low voltage areas.

Low voltage areas (LVA) are pivotal in atrial fibrillation (AF) pathogenesis, influencing local left atrial LA excitation and perpetuating AF occurrences. While pulmonary vein isolation (PVI) with cryo-balloon (CB) ablation is effective for AF, it doesn't provide insights into the LA substrate or detect LVA, which affects ablation success rates. This study examines whether LA voltage and LVAs can be anticipated by analyzing the voltage signal amplitude at the coronary sinus (CS) catheter, which is standard in CB and radiofrequency ablation procedures. A retrospective analysis of 284 patients with recurrent AF undergoing RF catheter ablation was conducted at a high-volume EP center in Germany. The correlation between LA voltage and LVA with the CS signal was explored. The signal amplitude in the CS significantly correlated with voltage in LA walls, particularly in the proximal CS (correlation coefficient ρ=0.81, p<0.001). A CS signal cut-off of 1.155mV effectively predicted severe atrial LVAs (>40%) with a sensitivity of 90.7% and a specificity of 100%. While a threshold of 1.945mV identified patients with no significant atrial LVAs (<5%) with a sensitivity of 88% and a specificity of 50% (AUC: 0.81, 95% CI: 0.71-0.89, p<0.001). The CS signal amplitude is associated with the LA voltage. Due to its potential as a diagnostic tool for atrial LVAs, the signal amplitude in the CS could provide valuable information about the LA substrate, especially when 3D mapping is not feasible.

Conflicting responses with simultaneous atrioventricular pacing. What is the mechanism?

A 60-year-old woman presented with recurrent episodes of palpitations, documented short RP, narrow QRS tachycardia and absence of preexcitation in the electrocardiogram during sinus rhythm. During an electrophysiology study, programmed stimulation induced a narrow QRS tachycardia with cycle length of 380 ms, VA interval of 164 ms and earliest atrial activation in the His region. Ventricular overdrive pacing failed to entrain the atrium even with isoprenaline infusion and atrial burst pacing repeatedly terminated the tachycardia. Difference in AH interval with pacing and SVT was 27 msec. Simultaneous atrial and ventricular pacing was done with atrial pacing from the high right atrium and showed a His signal as the first return electrogram suggestive of atrioventricular nodal reentrant tachycardia (AVNRT). The manoeuvre was repeated with atrial pacing from the proximal coronary sinus and showed an atrial signal as the first return electrogram suggestive of atrial tachycardia (AT). What is the explanation for the conflicting results of the two pacing maneuvers?

Multielectrode catheter-based pulsed field ablation of persistent and long-standing persistent atrial fibrillation

Abstract Background Rhythm control of non-paroxysmal atrial fibrillation (AF) is significantly more challenging, as a result of arrhythmia perpetuation promoting atrial substrate changes and AF maintenance. Purpose We describe a tailored ablation strategy targeting multiple left atrial (LA) sites via the multielectrode FarawaveTM pulsed field ablation (PFA) catheter in patients with persistent AF sustained beyond 6 months (PerAF&amp;gt;6m) and long-standing persistent AF (LSPAF). Methods The ablation protocol included the following stages: pulmonary vein antral and posterior wall isolation plus anterior roof line ablation (Stage 1); electrogram-guided substrate ablation (Stage 2); atrial tachyarrhythmia (AT) regionalization and ablation (Stage 3). Results Seventy-two [age:68±10y, 61.1%males; AF history: 25 (18-45) months] patients with PerAF&amp;gt;6m (52.8%) and LSPAF (47.2%) underwent their first PFA via the FarapulseTM system. LA substrate ablation (Stage 1 and 2) led to AF termination in 95.8% of patients. AF termination occurred while ablating the mitral edge of the postero-lateral ridge (40.3%), the inferior left atrium above the proximal coronary sinus (27.4%), the interatrial septum (22.6%), the superior aspect of the postero-lateral ridge (6.5%), the base of the appendage (3.2%). AF organized into a left-sided atrial flutter (AFlu) in 46 (74.2%) patients. The FarawaveTM catheter was used to identify LA sites showing diastolic, low-voltage electrograms and entrainment from its splines was performed to confirm the pacing site was inside the AFlu circuit (Figure 1). Left AFlu termination was achieved in all cases via PFA delivery. Total procedural and LA dwell times were 112±25min and 59±22 min, respectively. Major complications occurred in 2 (2.8%) patients with pre-existing left ventricular systolic dysfunction (EF&amp;lt;35%) who required inotropic therapy due to acute heart failure. Hemodynamics normalized within 24h and both patients were discharged after 2 and 3 additional hospital days. Transient ST-segment elevation was documented in 4 patients after peri-mitral PFA; timely nitrate administration led to ECG normalization within 10 minutes. Single-procedure success rate was 81.8% after 13.3±1.9 months of follow-up; AF-free survival was 93.1% (Figure 2). A subgroup of 36 patients completed a follow-up transthoracic echocardiography study to assess left atrial mechanical contraction changes after ablation. Median A-wave velocity was 30 (IQR: 20-35) cm/s post-ablation and 50 (IQR: 41-70) cm/s after a mean of 7.3±1.8 months post-ablation. Conclusions In our cohort, PFA-based AF substrate ablation led to AF termination in 95.8% of cases. Very favorable clinical outcomes were observed at one year of follow-up.Entrainment from the PFA Catheter.Kaplan-Meier Analysis.

Heterogenous atrial conduction in patients with hypertrophic cardiomyopathy and atrial fibrillation

Abstract Background/Introduction Hypertrophic cardiomyopathy (HCM) is characterised by myocardial thickening, fibrosis, and disarray, affecting both ventricles and atria. This pathology extends to atrial tissue, potentially influencing conductivity and contributing to arrhythmias, notably atrial fibrillation (AF). Pulmonary vein isolation to treat AF in HCM patients yields less satisfactory results compared to other patient groups. Improved understanding of the pathophysiology of AF in HCM patients could improve treatment stratification and delivery. Purpose This study aims to analyse atrial conduction properties in HCM patients with AF, compared to age, body mass index and sex-matched control patients. Methods Pre-ablation electroanatomic mapping data from 10 HCM patients and a matched control group of patients with structurally normal hearts undergoing AF ablation was retrospectively analysed. All patients underwent pre-ablation electroanatomic mapping during proximal coronary sinus pacing. This data was analysed using OpenEP software to quantify voltage mapping, conduction velocity and wave collision points. Conduction velocity was calculated using both plane fitting and triangulation methods. Wave collisions were identified by calculating the percentage of points with conduction velocity field divergence values less than -1.5. Results HCM patients exhibited significantly reduced mean left atrial bipolar voltage and greater low voltage burden &amp;lt;0.5mV than matched control patients (1.43mV vs. 2.14mV, p=0.0177; and 38.28% vs. 15.68%, p&amp;lt;0.0001), (Figure 1A and B). Wave collision points were significantly more prevalent in the HCM group (5.4% vs. 1.6%, p=0.0004), indicating more heterogeneous conduction (Figure 1C). Figure 2 shows example of divergence map with local electrograms around wave collision points. Both methods of quantifying conduction velocity showed comparable results. While average conduction velocity showed no statistically significant difference (plane fitting method - 0.61m/s in HCM group vs. 0.64m/s in control group, p = 0.465; triangulation method - 0.61m/s in HCM group, 0.64m/s in control group, p=0.393), a trend toward lower velocities in HCM patients was observed (Figure 1D and 1E). Conclusion HCM patients demonstrate significantly lower bipolar voltage and significantly greater low voltage areas than matched control patients. Atrial conduction in patients with HCM is significantly more heterogenous than matched control patients. These findings highlight marked conduction abnormalities in HCM patients which are likely to contribute to AF pathogenesis.

A Single Atrial Extrastimulation Resetting His Bundle During Supraventricular Tachycardia to Differentiate Atrial Tachycardia

BackgroundCatheter ablation is the curative treatment for paroxysmal supraventricular tachycardia (SVT). However, atrial tachycardia (AT) diagnosis is often challenging, especially when SVT is terminated by pacing. ObjectivesThis study sought to develop a novel method for AT diagnosis. MethodsA total of 147 SVTs including 28 ATs, 87 atrioventricular nodal re-entrant tachycardias, and 32 orthodromic reciprocating tachycardias were prospectively studied. Single atrial extrastimulation was performed at the proximal coronary sinus from a coupling interval 20 milliseconds shorter than the tachycardia cycle length and gradually decreased until the His bundle (HB) was first reset and further until the SVT was terminated. The response of the SVT during the first HB resetting and the termination pattern were examined. ResultsIn 27 of 28 ATs, tachycardia was unaffected when HB resetting whereas, in atrioventricular nodal re-entrant tachycardias or orthodromic reciprocating tachycardias (non-AT), tachycardia was simultaneously reset when HB resetting or was terminated with an atrio-Hisian block. When the coupling interval was further shortened for cases in which tachycardia persisted, all 33 SVTs with tachycardia termination with atrio-Hisian block were non-ATs, whereas 5 ATs and 7 non-ATs were terminated with Hisian-atrial block. The sensitivity, specificity, and positive and negative predictive values of the pattern of tachycardia that was unaffected when HB resetting for AT diagnosis were 96%, 100%, 100%, and 99%, respectively. Those of the pattern of tachycardia termination with atrio-Hisian block for non-AT diagnosis were 92%, 100%, 100%, and 42%, respectively. ConclusionsSingle atrial extrastimulation from the proximal coronary sinus during tachycardia was useful and effective for AT diagnosis.

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.

Decrement Evoked Potential (DEEP) Mapping of the Atria: Unmasking Atrial Fibrillation Substrate.

Atrial myopathy may underlie the progression of atrial fibrillation (AF) from a treatable disease to an irreversible condition with poor ablation outcomes. Electrophysiological methods to unmask areas prone to re-entry initiation could be key to defining latent atrial myopathy. Consecutive patients referred for AF ablation were prospectively included at four institutions. Decrement evoked potential mapping (DEEP) was performed in eight left atrial sites and five right atrial sites, from two different pacing locations (endocardially from the left atrial appendage, epicardially from the proximal coronary sinus). The electrograms (EGMs) during S1 600 ms drive and after an extra stimulus (S2 at+30 ms above atrial refractoriness) were studied at each location and assessed for decremental properties. Follow-up was 12 months. Seventy-four patients were included and 85% had persistent AF. A total of 17,614 EGMs were individually analysed and measured. Nine percent of the EGMs showed DEEP properties (local delay of >10 ms after S2) with a mean decrement of 33±26 ms. DEEPs were more frequent in the left atrium than the right atrium (9.4% vs 8.0%; p<0.001) and more prevalent in persistent AF patients than paroxysmal AF patients (9.8% vs 4.6% p=0.001). Atrial DEEPs were more frequently unmasked in normal bipolar voltage areas and by epicardial pacing than endocardial pacing (9.6% vs 8.4%, respectively; p=0.004). Within the left atrium, the roof had the highest prevalence of DEEP EGMs. DEEP mapping of both atria is useful for highlighting areas with a tendency for unidirectional block and re-entry initiation. Those areas are more easily unmasked by epicardial pacing from the coronary sinus and more prevalent in persistent AF patients than in paroxysmal AF patients.

Incremental value of maximum voltage and activation-guided ablation for cavotricuspid isthmus-dependent atrial flutter

Abstract Funding Acknowledgements Type of funding sources: None. Radiofrequency (RF) catheter ablation is an effective method for treatment of typical cavo-tricuspid isthmus (CTI) dependent atrial flutter. However, despite the widespread use of contact force irrigated catheter, 11% of patients don’t achieve a first-pass CTI block, requiring additional RF applications or additional line during the same or a second procedure. From an anatomical point of view, CTI is composed of discrete bundles of muscle with intervening connective tissue, suggesting that its conduction proprieties are dependent of the anatomic architecture of the bundles. The maximum voltage-guided (MGV) ablation technique targets high-voltage electrograms along CTI to ablate the functionally active anatomic muscle bundle, without drawing a complete anatomic line. [1;2] Purpose The aim of this study was to evaluate the efficacy of maximum voltage and activation-guided ablation (MVG/LAT) for CTI atrial flutter in real-world setting. Methods This was a prospective observational study in which all patients undergoing CTI atrial flutter ablation at the Electrophysiology Laboratory of our Department from 01/2021 to 10/2022 were recruited. Patients who were undergoing the ablation procedure after having already made an unsuccessful attempt of the same were excluded from the study. Substrate and activation mapping of CTI, both during flutter and during pacing from the proximal coronary sinus (CSp), was performed in all patients, identifying the earliest activated high-voltage channels, without the use of fluoroscopy, using the Smart-Touch SF catheter (CARTO 3, V7, Biosense Webster). High-voltage channels were validate also during lateral RA pacing. CTI ablation was performed only in channels with high voltage and early activation (W 45, AI 500). Bidirectional CTI block were validate by differential atrial pacing maneuvers and activation mapping during pacing from CSp. Results Procedural data of 39 patients were evaluated (mean age 68±13 years; men 92.6%; mean right atrium volume 149 mL). The mean number of points taken per map per patient was 1151. Bipolar thresholds were customized (0.5-2.5 mV) with the aim of better visualizing high-voltage channels. In 20/39(51.2%) patients ablation was performed during atrial flutter, in 19/39(48.8%) during pacing from proximal CS. In 19/39(48.8%) patients high-voltage channels were not detected at the central isthmus line (6 o'clock, LAO). The median number of RF applications to achieve bidirectional block of the CTI were 6 (1-20) in all patients (p=NS) (Figure 1,2). During a mean follow-up of 260 days (90-531) no recurrences were documented in any patient. Conclusions MVG/LAT-guided ablation, targeting selectively conductive muscle fibers, decreases the number of RF applications and improves efficacy, mostly in patients with challenging anatomies.

A single atrial stimulation resetting his bundle during tachycardia: a new diagnostic methods of atrial tachycardia distinguishing from other tachycardias

Abstract Funding Acknowledgements Type of funding sources: None. Backgrounds Catheter ablation for paroxysmal supraventricular tachycardia (PSVT) is curative treatment. However, diagnosis of atrial tachycardia (AT) distinguishing from other PSVTs are often challenging, especially when the tachycardia terminates after pacing or does not sustain long enough for diagnostic maneuvers. We sought a new method for diagnosis of AT. Methods One-hundred and thirty-four PSVTs including 20 ATs, 84 atrioventricular nodal reentrant tachycardias (AVNRTs) and 30 orthodromic reciprocating tachycardias (ORTs) were studied. Single atrial stimulation was started at intervals of 20ms shorter than the tachycardia cycle length during the tachycardia and coupling interval was shortened by 10ms. The pacing was performed from the proximal coronary sinus, which was not the earliest excitatory site, and pacing continued until the His potential was reset or the tachycardia terminated. The incidence of tachycardia resetting and the patterns of tachycardia termination were examined. Results Resetting of His was obtained in all AT patients without tachycardia termination. All ATs were not reset despite of His resetting.(Figure 1A) In AVNRTs or ORTs patients, 31 tachycardias (27%) were terminated with AH block before His resetting. In the 83 AVNRTs or ORTs, tachycardia was also reset when His was reset simultaneously.(Figure 1B) When tachycardia resetting was not observed despite His resetting, the diagnostic power of AT was 100% in sensitivity, specificity, positive predictive value, and negative predictive value. All cases which PSVTs were terminated before His resetting were AVNRTs or ORTs.(Figure 2) Conclusions A single atrial programmed stimulation resetting His during tachycardia was effective for differentiating PSVT even in cases that tachycardia terminates by the pacing.

PO-05-147 RIGHT ON Q: WIDE-COMPLEX TACHYCARDIA IN SETTING OF DEXTROPOSITION

Dextroposition is a rare cardiac malformation defined as rightward cardiac displacement with leftward apex, vs. dextrocardia, which is rightward base-axis orientation. We report the second known case of dextroposition with accessory pathway, presenting as preexcited atrial tachycardia. Abnormal anatomy complicates ECG localization and pathway ablation. N/A N/A A 50-year-old woman was admitted with respiratory distress due to EBV infection. Chest X-ray showed right-sided heart. A month later, she presented in wide-complex tachycardia, rate 205 bpm. She was cardioverted after minimal response to procainamide/adenosine. Post-cardioversion ECG showed short PR interval and preexcitation, confirming presence of accessory pathway. However, the wide-complex tachycardia had morphology identical to baseline, supporting preexcited atrial tachycardia over AVRT. Despite X-ray findings and reverse R-wave progression in precordial leads, presence of left axis deviation and initial negative deflection in aVR argued against dextrocardia. Moreover, aVR had negative T- and P-waves, findings associated with levocardia. Thus, dextroposition was suspected. Millstein and Arruda criteria suggested posteroseptal accessory pathway, but no data on their applicability in right-sided heart exist. EP study was performed. Eccentric VA conduction was noted. Earliest activation was at proximal coronary sinus. During isoproterenol infusion, patient went into atrial tachycardia, cycle length 420ms. Multiple AT foci were identified, including at right atrial appendage and tricuspid annulus. During ablation, patient developed atrial fibrillation with preexcited RR <250ms, confirming high-risk accessory pathway. Given numerous AT foci and high risk, it was decided to focus on pathway over tachycardia sites. Pathway was successfully ablated at ostia of coronary sinus and middle cardiac vein. One prior case of accessory pathway ablation in dextroposition has been reported. This patient had left lateral pathway and multiple congenital abnormalities including lung hypoplasia. While our patient was found to have multifocal atrial tachycardia, she had no clinical or radiographic lung disease. ECG changes in dextroposition are less predictable than in dextrocardia; they vary with cardiac rotation, axis position, and lead position. Comorbid accessory pathway is rare; ECG-anatomy relationship is ill-defined. Structural abnormalities pose individual challenges during electrophysiologic procedures.

PO-02-229 AUTOMATED LOCALIZATION OF ATRIAL ECTOPIC BEATS USING 12-LEAD ECG MEAN SPATIO-TEMPORAL VECTOR POSITION: IMPORTANCE OF INCORPORATING PATIENT-SPECIFIC ANATOMIC MODELS

Localizing the origin of atrial ectopic activity from the 12-lead ECG can be challenging, particularly in patients with atrial pathology. To identify the origin of paced atrial ectopic beats (simulating atrial ectopy) using software that quantifies the mean spatio-temporal vector position of cardiac depolarization projected onto generic and patient-specific atrial models. 12-lead ECG data were collected during sinus rhythm (SR) and during regular pacing from the high and low right atrium (HRA/LRA), proximal and distal coronary sinus (CS), pulmonary veins (LSPV, LIPV, RSPV, RIPV), and left atrial appendage (LAA). The origin and trajectory of the atrial signals were calculated with software that analyzes P-waves from the 12-lead ECG and automatically constructs a net vector of electrical activity projected onto a standard generic model of human atria (CineECG; Nieuwerbrug, The Netherlands). The model atria were split into 9 segments, and the software accuracy was scored based on localization of the paced atrial signal origin to the correct segment. To see if patient-specific anatomy improved localization, we also incorporated atrial anatomy from cardiac MRIs acquired from a subset of 12 patients and compared localization to the generic model. We enrolled 19 patients (mean age 70±9, 4 female) with paroxysmal (63%) or persistent (37%) AF and left atrial (LA) enlargement (mean LA volume 58 cc/m2) undergoing pulmonary vein isolation for treating AF. Using the generic atrial model, the software correctly localized 105/142 (74%) beats to the correct atrial segment (Figure). Accuracy was better for RA compared to LA signals (90% vs. 62%, p < 0.05). Localization worked best in the coronary sinus (19/19, 100%) and worst in the LPVs (14/33, 42%). Patient-specific models improved localization of PV signals, particularly left-sided ones (generic vs. patient-specific: RPVs 70% vs 85%, p = 0.36, LPVs 42% vs 76%, p = 0.03). Accuracy improved and was similar for RA vs. LA localization when using patient-specific models (90% vs. 82%, p = 0.48). The novel software algorithm can automatically localize paced signals in both the left and right atria despite significant atrial pathology. Patient-specific anatomic models improve localization. This software holds promise for automatically localizing and classifying atrial arrhythmias and guiding therapy, including catheter ablation, based on standard 12-lead ECG data.

PO-02-096 USE OF ISOCHRONAL LATE ACTIVATION MAPPING OF THE CAVOTRICUSPID ISTHMUS TO PREDICT INDUCIBILITY OF TYPICAL ATRIAL FLUTTER

Isochronal late activation mapping (ILAM) was initially described in reentrant ventricular tachycardia to characterize the functional substrate responsible for arrhythmia propagation. Recently, this mapping technique was successfully applied to atypical atrial flutter, but it has yet to be applied to the prototypical reentrant arrhythmia: typical atrial flutter (AFL). Our objective was to examine the relationship between slow conduction in the cavotricuspid isthmus utilizing ILAM mapping and the presence of typical AFL. A cohort of patients undergoing atrial fibrillation (AF) and AFL ablation at our institution with ILAM mapping of the right atrium were included in this study. Right atrial ILAM map was performed by pacing the proximal coronary sinus at a pacing cycle length of 400 ms. Mapping was performed using a multipolar catheter with Ensite Precision (Abbott) annotating the latest signal on each pair of bipoles. Isochronal crowding was present if more than 3 isochrones were present within 1 cm. After mapping, burst atrial pacing at numerous cycle lengths was performed in attempts to induce AFL. Fifteen patients undergoing AF and/or AFL ablation had right atrial ILAM performed and were included. Of those, 14 (93%) and 7 (47%) had a history of AF and AFL respectively. Isochronal crowding was present in 10 (67%) patients and AFL was induced in 7 (47%) patients. Atrial flutter was inducible in 71% of patients with a history of AFL and 25% of patients without a history of AFL. All 7 patients with a history of AFL and all 7 patients with induced AFL had isochronal crowding present on ILAM. Only 1 patient with isochronal crowding did not have a history of AFL or inducible AFL. In this limited case series, we report that isochronal crowding was present in every patient that had a history of AFL. Furthermore, crowding was also present in every patient that had inducible AFL even if they had no clinical history of AFL.

High-density electroanatomic activation mapping to guide slow pathway modification in patients with persistent left superior vena cava

Slow pathway (SP) mapping and modification can be challenging in patients with persistent left superior vena cava (PLSVC) due to anatomic variance of the Koch triangle (KT) and coronary sinus (CS) dilation. Studies using detailed 3-dimensional (3D) electroanatomic mapping (EAM) to investigate conduction characteristics and guide ablation targets in this condition are lacking. The purpose of this study was to describe a novel technique of SP mapping and ablation in sinus rhythm using 3D EAM in patients with PLSVC after validation in a cohort with normal CS anatomy. Seven patients with PLSVC and dual atrioventricular (AV) nodal physiology who underwent SP modification with the use of 3D EAM were included. Twenty-one normal heart patients with AV nodal reentrant tachycardias formed the validation group. High-resolution, ultra-high-density local activation timing mapping of the right atrial septum and proximal CS in sinus rhythm was performed. SP ablation targets were consistently identified by an area in the right atrial septum with the latest activation time and multicomponent atrial electrogram adjacent to a region with isochronal crowding (deceleration zone). In PLSVC patients, these targets were located at or within 1 cm of the midanterior CS ostium. Ablation in this area led to successful SP modification, reaching standard clinical endpoints with a median of 43 seconds of radiofrequency energy or 14 minutes of cryoablation without complications. High-resolution activation mapping of the KT in sinus rhythm can facilitate localization and safe SP ablation in patients with PLSVC.

Narrow QRS complex tachycardia with and without ventriculoatrial block: What is the mechanism?

A 39-year-old woman with no structural heart disease underwent an electrophysiology study (EPS) to assess recurrent supraventricular tachycardia (SVT). The electrocardiogram did not show any preexcitation. The baseline atrio-His and His-ventricular intervals were 108 and 43 ms. Ventricular pacing demonstrated concentric, decremental ventriculoatrial (VA) conduction, and the single jump changed the earliest atrial activation site (EAAS) from the His bundle region to the proximal coronary sinus (CS) region.

The hemodynamic effect of simulated atrial fibrillation on left ventricular function.

Atrial fibrillation (AF) is the most common sustained arrhythmia in humans. The onset of the arrhythmia can significantly impair cardiac function. This hemodynamic deterioration has been explained by several mechanisms such as the loss of atrial contraction, shortening of ventricular filling, or heart rhythm irregularity. This study sought to evaluate the relative hemodynamic contribution of each of these components during in vivo simulated human AF. Twelve patients undergoing catheter ablation for paroxysmal AF were paced simultaneously from the proximal coronary sinus and the His bundle region according to prescribed sequences of irregular R-R intervals with the average rate of 90and 130 bpm, which were extracted from the database of digital ECG recordings of AF from other patients. The simulated AF was compared to regular atrial pacing with spontaneous atrioventricular conduction and regular simultaneous atrioventricular pacing at the same heart rate. Beat-by-beat left atrial and left ventricular pressures, including LV dP/dT and Tau index were assessed by direct invasive measurement; beat-by-beat stroke volume and cardiac output (index) were assessed by simultaneous pulse-wave doppler intracardiac echocardiography. Simulated AF led to significant impairment of left ventricular systolic and diastolic function. Both loss of atrial contraction and heart rate irregularity significantly contributed to hemodynamic impairment. This effect was pronounced with increasing heart rate. Our findings strengthen the rationale for therapeutic strategies aiming at rhythm control and heart rate regularization in patients with AF.

A narrow QRS complex tachycardia: What is the mechanism?

A 45-year-old man complained of recurrent episodes of palpitations. Twelve-lead electrocardiograms revealed a long RP and regular narrow QRS complex tachycardia. The baseline atrio-His and His-ventricular intervals were 130 and 55 ms, respectively. A narrow QRS complex tachycardia with a cycle length of 407 ms was reproducibly induced by a single atrial or ventricular extrastimulus. During the tachycardia, the atrial activation sequence with earliest activation in the proximal coronary sinus was identical to the retrograde atrial activation sequence during right ventricular pacing.

Precordial reverse pattern break: A predictor of posteroseptal accessory pathways ablatable from the proximal coronary sinus.

Posteroseptal accessory pathways (PSAPs) occasionally may lie within the coronary sinus (CS) or its tributaries, in a CS diverticulum, or along the epicardial surface. Catheter ablation is challenging in this subset of patients.1 Certain electrocardiographic (ECG) characteristics have been described in patients with proximal coronary sinus (PCS)-related PSAPs.1,2 We encountered precordial

Study of coronary sinus anatomy during levophase of coronary angiography.

BACKGROUNDCoronary sinus (CS) imaging has recently gained importance due to increasing need for mapping and ablation of electrophysiological arrhythmias and left ventricular (LV) pacing during cardiac resynchronization therapy (CRT). Retrograde venogram is the current standard for imaging CS and its tributaries. AIMTo evaluate CS anatomy during levophase of routine coronary angiography to aid LV lead implantation during CRT.METHODSIn this prospective observational study, 164 patients undergoing routine coronary angiography for various indications (Chronic stable angina-44.5%, acute coronary syndrome- 39.5%, Dilated cardiomyopathy-11%, atypical chest pain-5%) were included. Venous phase (levophase) of left coronary injection was recorded in left anterior oblique - cranial and right anterior oblique -cranial views. Visibility of coronary veins, width and shape of CS ostium, angulations of proximal CS with body of CS were noted. Presence, size, take-off angle and tortuosity of posterolateral vein (PLV), anterior interventricular veins (AIV) and middle cardiac vein (MCV) were also noted.RESULTSDuring levophase, visibility grade (Muhlenbruch grade) for coronary veins was 3 in 74% and 2 in 26% of cases. Visibility of CS did not correlate with body mass index. The diameter of CS ostium was < 10 mm, 10-15 mm and > 15 mm in 48%, 42% and 10% of patients respectively. Proximal CS was tubular in 136 (83%) patients and funnel-shaped in 28 (17%) patients. Sharp take-off angulation between ostium and body of CS was seen in 16 (10%) patients. Two or more PLV were present in 8 patients while PLV was absent in 52 (32%) patients. Angle of take-off of PLV with body of CS was favourable (0°-45°) in 65 (40%) patients. The angle was 45°-90° in 36 patients and difficult take-off angle (> 90°) was seen in 8 patients. Length of PLV reached distal third of myocardium in 84 cases and middle third in 11 cases. There was no tortuosity in 79 cases, a single bend in 29 cases and more than 2 bends in 4 cases. Thirty nine (24%) patients had other veins supplying posterior/Lateral wall of LV. There was a single vein supplying lateral/posterior wall in 31 (19%) patients. Diameter of MCV and AIV was significantly larger in patients with absent PLV as compared to patients with a PLV. CONCLUSIONLevophase study of left coronary injection is effective in visualization of the CS in almost all patients undergoing coronary angiography and may be an effective alternative to retrograde venogram in patients with LV dysfunction or LBBB.