Entire Left Atrium Research Articles

Changes in epicardial adipose tissue volume before and after cryoballoon ablation in patients with atrial fibrillation: Supporting the “AF begets EAT” theory

BackgroundEpicardial adipose tissue (EAT) is closely associated with atrial fibrillation (AF), suggesting that it may be one of the causes of AF progression. However, it is unclear whether AF affects EAT. ObjectiveThis study aimed to demonstrate that sinus rhythm restoration reduces EAT volume (EATV) through left atrial reverse remodeling (LARR). MethodsWe analyzed data from 247 patients who underwent cryoballoon ablation for AF. EATV was assessed by contrast-enhanced computed tomography with a 3-dimensional analysis workstation, evaluating EATV surrounding the entire heart (Total-EATV) and left atrium (LA-EATV) at baseline and 6 months after cryoballoon ablation. ResultsAt 6 months, all patients but one with persistent AF were in sinus rhythm. Total-EATV and LA-EATV were both significantly decreased in patients with persistent AF (n = 33; Total-EATV: 148.8 ± 53.3 mL to 142.9 ± 53.5 mL [P = .01]; LA-EATV: 26.8 ± 11.3 mL to 25.2 ± 10.7 mL [P = .01]). No changes were observed in patients with paroxysmal AF (n = 214). Persistent AF was more strongly associated with LARR than paroxysmal AF (odds ratio, 2.34; 95% confidence interval, 1.01–5.44; P = .05). LARR showed an independent correlation with both Total-EATV and LA-EATV reduction (odds ratio, 1.78 [P = .04] and 2.80 [P < .001], respectively). ConclusionThese findings suggest a novel “AF begets EAT” theory, complementing the previously accepted role of EAT as a cause of AF and supporting the “AF begets AF” mechanism.

The impact of left atrial morphology on thrombosis risk in atrial fibrillation

Atrial fibrillation (AF) is an arrhythmia disease that can disrupt the movement of the left atrium (LA), which will facilitate thromboembolism in LA and further exacerbate the stroke risk. The left atrial appendage (LAA) is a vital site for thrombus formation. The morphology of the LAA is believed to have a profound effect on thrombosis. However, due to the limitation of observation and monitoring methods, the mechanism of this effect is still unrevealed. Virchow's triad is a theory of thrombogenic mechanisms, stating that endothelial injury, blood hypercoagulability, and blood stasis are the three main factors involved in thrombus formation. In this study, we conducted personalized simulation analyses for 12 AF patients and discussed simulation results from the perspective of Virchow's triad. The simulation results indicate the effectiveness of Virchow's triad in elucidating the thrombosis mechanism within the LAA. The LAA is more prone to thrombosis than the other region of LA, because of the lower blood flow velocity and significantly higher endothelial cell activation potential values there, which indicates a higher risk of blood stasis and endothelial injury, respectively. Furthermore, a comprehensive score is proposed to assess the performance of Virchow's triad in the LAA. The morphology of LA has a significant influence on the performance of the three factors in Virchow's triad. Hence, for a quickly assessment of LAA thrombosis risk in AF patients through the lens of Virchow's triad, we need a more refined shape scoring system that can better reflect patient-specific morphological features of the entire LA.

The omnipolar voltages as an ablation indicator for pulmonary vein isolation in patients with atrial fibrillation

Abstract Background Lesion Index (LSI) without considering myocardial voltage is well-known to guide pulmonary vein isolation (PVI) ablation using the TactiCath™ Ablation Catheter in paroxysmal atrial fibrillation (PAF) patients. However, some patients show gaps after LSI-guided PVI ablation. Meanwhile, the omnipolar voltages detected using EnSite™ Omnipolar Technology (OT) have been reported to improve the underestimation of voltage. Purpose We aimed to clarify their differences by comparing the omnipolar voltages with conventional bipolar voltages and to verify whether it could be an additional indicator of LSI. Methods [Study1] We retrospectively studied 48 PAF patients (32 male, 69±8yrs) who received catheter ablation (CA). The left atrial voltage mapping was performed with Advisor™ HD Grid Mapping Catheter under right atrial pacing. The voltages within a 1cm diameter circle were measured at each site (Roof, Anterior, Posterior, Septal, Lateral; 238 sites) and evaluated the omnipolar and conventional bipolar voltages. [Study2] Twelve patients (8 males, 71±9yrs) with PAF who underwent CA were prospectively studied. The left atrial voltage mapping was performed before PVI ablation. The pre-ablation omnipolar voltages / bipolar voltages and LSI on each ablation site (558 points) of the PVI line were measured and compared in gapped and non-gapped regions. The gapped areas were defined as sites that required additional ablation after the first-round ablation of PVI. Results [Study1] The omnipolar voltages were higher than the bipolar voltages (total 238 sites, 2.84±2.05 vs. 2.67±1.81 mV, P&amp;lt;0.0001) in the entire left atrium. There was no feature in the difference between the omnipolar voltage and the bipolar voltage, according to the site and the voltage height (Figure). [Study2] Five gaps (14 ablation points) were confirmed after the first round of LSI-guided PVI (LSI 4.5±0.4, minimum 3.8 - maximum 5.8) in 4 of 12 patients. The omnipolar voltage in the gapped areas was higher than the non-gapped areas (544 ablation points) (5.64±1.93 vs. 3.73±2.82mV, P=0.0118, cut-off value 3.56mV, the area under the curve 0.74678). Meanwhile, there was no difference between the gapped and non-gapped areas in LSI and the conventional bipolar voltage. Conclusion Although the omnipolar voltage obtained by OT is detected only slightly higher than the bipolar potential, the higher omnipolar voltage could be an indicator of additional ablation to the LSI.

Abstract 16865: Epicardial Adipose Tissue Density Predicts the Presence of Atrial Fibrillation and Its Recurrence After Catheter Ablation: Three-Dimensional Reconstructed Image Analysis

Introduction: Epicardial adipose tissue (EAT) induces inflammation in the atria and is associated with atrial fibrillation (AF). Several studies have examined the relationship between EAT volume (EAT-V) and density (EAT-D) and the recurrence of AF after catheter ablation. However, the conclusions of these studies have not always been consistent, which might be due to the differences in the location and method of EAT measurement. Methods: This study included 43 consecutive patients who underwent catheter ablation for AF and 30 control patients with no documented history of AF who were matched for baseline characteristics. EAT-V and EAT-D around the entire heart, both atria, left atrium (LA), and right atrium (RA) were measured in detail using reconstructed three-dimensional (3D) EAT images from dual-source computed tomography before ablation. Results: None of the measurements of EAT-V differed significantly between patients with AF and controls or between patients with recurrent AF and those without. On the other hand, all measurements of EAT-D were higher in patients with AF than in controls (both atria, p&lt;0.001; RA, p&lt;0.001; LA, p=0.002). All EAT-D measurements were associated with the presence of AF. Among patients with AF who underwent ablation, all EAT-D measurements were higher in patients with recurrent AF than in those without. The difference was significant for EATRA-D (p=0.032). All atrial EAT-D values predicted recurrent AF (EATRA-D: hazard ratio [HR], 1.208; 95% confidence interval [95%CI], 1.053-1.387; p=0.007; EATLA-D: HR, 1.108; 95% CI,1.001-1.225; p=0.047; EATatrial-D: HR, 1.174; 95% CI,1.040-1.325; p=0.010). According to the ROC curve analysis, EATatrial-D&gt; –80.9 HU is associated with AF recurrence with 100% sensitivity and 58% specificity (AUC, 0.75; p&lt;0.05), and EATRA-D &gt; –80.9 HU could distinguish patients with AF recurrence with 86% sensitivity and 61% specificity (AUC, 0.76; p&lt;0.01). However, EATLA-D &gt; –85.3 HU had low accuracy (sensitivity, 100%; specificity, 33%; AUC, 0.65; p=0.209). Conclusion: For predicting the presence of AF, 3D analysis of EAT-D, rather than EAT-V, is useful. Peri-atrial EAT-D is responsible for recurrent AF after ablation and useful for predicting recurrent AF after catheter ablation.

Survivors of Pediatric Hematopoietic Stem Cell Transplantation Exhibit Progressive Diastolic Dysfunction Over Years of Follow-Up

Patients who have undergone hematopoietic stem cell transplantation (HSCT) in childhood have a higher risk of diastolic heart failure (HF). The rate of progression of diastolic dysfunction in aging pediatric patients is unknown and is more difficult to assess in young patients secondary to changes in diastolic indices as they grow. HSCT recipients at our center were previously found to have decline in diastolic function indices at 1 year after HSCT. This study provides follow-up of this cohort, using age-normalized z-scores to assess whether the decline in diastolic function noted at 1-year post-HSCT persists, worsens, or improves over time. Patients age <21 years who underwent HSCT at Boston Children's Hospital/Dana-Farber Cancer Center between 2005 and 2008 with ≥3 surveillance echocardiograms, including 1 performed pre-HSCT, were included. Diastolic measures included mitral inflow (E/A ratio) and Doppler tissue imaging of left ventricular lateral wall (LV lateral e'), LV septal wall (septal e') and right ventricular free wall (RV e'). Systolic function was measured by LV ejection fraction (LVEF). Normalization by age was done using z-scores, and >±2 SD was defined as abnormal in linear modeling of diastolic dysfunction and systolic dysfunction over time. In a subset of patients with adequate post-HSCT images of the entire left atrium (LA), LA volume and LA strain analyses also were performed. The study cohort comprised 61 patients (41% female; median age at HSCT, 10.7 years; median follow-up, 7.4 years). Diastolic index z-scores declined by -.045/year for LV lateral e', -.06/year for LV septal e', and -.14/year for RV e' (P < .01). The E/A ratio z-score increased by .034/year (P=.028). Linear modeling demonstrated that LV lateral e' and LV septal e' would become abnormal at 25 and 20 years post-HSCT, respectively, whereas RV e' would become abnormal sooner, at 12.6 years. LVEF z-score declined by -.04/year (P < .01) and was estimated to become abnormal at 40 years post-HSCT. Exposure to total body irradiation (TBI) was associated with worsening diastolic indices, lower LVEF (P ≤ .002), and decreased LA reservoir strain (42.0% versus 45.0%; P=.016) and conduit strain (-31.5% versus -35.1%; P=.029), although there was significant overlap between TBI and anthracycline exposure. Treatment with anthracyclines even at low doses (median, 150 mg/m2) was associated with declining LVEF but not with changes in diastolic indices. Long-term survivors of childhood HSCT exhibit declines in both LV and RV diastolic function indices. These results inform the rate of progression of LV and RV diastolic dysfunction indices over time in long-term survivors of pediatric HSCT. A significant association was observed between TBI and diastolic dysfunction and a decline in LVEF. Treatment with anthracyclines even at low doses was associated with a mild decline in LVEF. Our results can inform a lifespan perspective on disease management in this population, encourage clinicians and patients to be vigilant in following guideline-directed surveillance echocardiography, and inform anticipatory responses by clinicians as patients transition from pediatric care to adult care.

Spatial correlation of left atrial low voltage substrate in sinus rhythm versus atrial fibrillation: The rhythm specificity of atrial low voltage substrate.

Improved sinus rhythm (SR) maintenance rates have been achieved in patients with persistent atrial fibrillation (AF) undergoing pulmonary vein isolation plus additional ablation of low voltage substrate (LVS) during SR. However, voltage mapping during SR may be hindered in persistent and long-persistent AF patients by immediate AF recurrence after electrical cardioversion. We assess correlations between LVS extent and location during SR and AF, aiming to identify regional voltage thresholds for rhythm-independent delineation/detection of LVS areas. (1) Identification of voltage dissimilarities between mapping in SR and AF. (2) Identification of regional voltage thresholds that improve cross-rhythm substrate detection. (3) Comparison of LVS between SR and native versus induced AF. Forty-one ablation-naive persistent AF patients underwent high-definition (1 mm electrodes; >1200 left atrial (LA) mapping sites per rhythm) voltage mapping in SR and AF. Global and regional voltage thresholds in AF were identified which best match LVS < 0.5 mV and <1.0 mV in SR. Additionally, the correlation between SR-LVS with induced versus native AF-LVS was assessed. Substantial voltage differences (median: 0.52, interquartile range: 0.33-0.69, maximum: 1.19 mV) with a predominance of the posterior/inferior LA wall exist between the rhythms. An AF threshold of 0.34 mV for the entire left atrium provides an accuracy, sensitivity and specificity of 69%, 67%, and 69% to identify SR-LVS < 0.5 mV, respectively. Lower thresholds for the posterior wall (0.27 mV) and inferior wall (0.3 mV) result in higher spatial concordance to SR-LVS (4% and 7% increase). Concordance with SR-LVS was higher for induced AF compared to native AF (area under the curve[AUC]: 0.80 vs. 0.73). AF-LVS < 0.5 mV corresponds to SR-LVS < 0.97 mV (AUC: 0.73). Although the proposed region-specific voltage thresholds during AF improve the consistency of LVS identification as determined during SR, the concordance in LVS between SR and AF remains moderate, with larger LVS detection during AF. Voltage-based substrate ablation should preferentially be performed during SR to limit the amount of ablated atrial myocardium.

Omnipolar mapping improves substrate characterization and critical isthmus identification in atypical atrial flutters

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Characterizing atrial substrate and conduction properties is crucial to treat complex arrhythmias during catheter ablations. Unipolar and bipolar electrogram signals are routinely used with significant limits due to low detailed mapping, the impact of poor contact and far-field electrical signals. Moreover, signals morphology is dependent on the relative orientation of the catheter inter-electrode axis to the direction of activation. Omnipolar signals try to overcome this direction-dependence by using three adjacent electrodes to infer directional information about the local electric field. Purpose We compared omnipolar mapping (OM) signals with the traditional high-density bipolar mapping (BM) ones. Methods All the procedures were performed using a high-density grid-designed mapping catheter. The atypical left atrial flutters were mapped using both OM and BM configuration. All the analysis about voltage and potential duration are related to the entire left atrial surface excluding pulmonary veins. Results Ten atypical atrial flutters were mapped in the left atrium in seven patients (median age 70 y, 5 males). OM identified 7 double loops and 3 triple loops while BM identified 7 double loops, 2 triple loops and 1 single loop, missing 2 critical circuits (an example is shown in figure 1) Significant differences were present also in potentials amplitude (peak-to-peak voltage amplitude) in the critical isthmus with OM higher than BM (OM median 0.22 mV IQR [0.16 – 0.30] vs BM median 0.19 mV IQR [0.13 – 0.24], P= 0.002). Dense scar area (defined as voltage amplitude &amp;lt;0.05 mV) identified with OM was smaller compared to BM (1.3 cm2 IQR [0.13-1.73] vs 1.7 cm2 IQR [0.23-3.10]; P= 0.06). OM showed longer signal duration (+10.1%) compared to BM in the entire left atrium and in particular the mean signal duration in the critical isthmus (OM median 79.1 ms IQR [70.7 – 88.9] vs BM median 62.5 ms IQR [55.2 – 85.2], P= 0.006). Percentage of tachycardia cycle lenght (TCL) mapped at the critical isthmus (maximum signal duration at the isthmus/ TCL) was greater with OM than BM (OM mean 60% ± 11%, BM mean 54% ± 12% (P= 0.02)(a summary of the results are shown in table 1). Conclusions OM identifies higher amplitude and longer signal duration especially in the critical isthmus region also reducing the extension of dense scar area. This finding may be crucial in the definition of complex and localized reentrant activities, leading to a faster and more precise catheter ablation.

Abstract 14297: Spatially Synchronized Electrogram Islands Within Atrial Fibrillation Predict Termination by Ablation

Introduction: It is unclear how persistent atrial fibrillation (AF) terminates by any spatial arrangement of ablation lesions. Hypothesis: We hypothesized that AF that exhibits spatial organization with islands of 1:1 synchronized electrograms within the disordered milieu and, specifically, that patients with larger area islands may be more likely to terminate than those without. Methods: We recruited n=60 patients (72% male, age 63±10 years) in whom AF terminated by ablation (n=30; “Term”) or did not (n=30, “Non-term”). Unipolar AF electrograms were recorded by 64-pole basket catheters in both atria. For all possible 2X2 electrode grids, synchronization was assessed by correlation (repeating shapes + relative timings, coefficient, Fig A). Ablation targeted organized sites (rotational/ focal), then pulmonary vein isolation. Results: Fig A shows (top) AF EGMs in a Term patient showing 1:1 patterns at D2-D3-E2-E3 over time (correlation&gt;0.9). For the entire left atrium, there was a large synchronized island &gt;25% of mapped atria (Fig B, red). Bottom panels show less synchronization in a Non-term patient (Fig A), with &lt;5% area (Fig B). For all patients, synchronized islands (with correlation &gt;0.8) were larger for Term (black) than Non-term (gray) patients over a range of time durations (Fig C, p&lt;0.01 ANOVA). Area of synchronized regions predicted AF termination with c-statistic 0.68, and the optimum cut-point provided sensitivity 87% (specificity 43%). Conclusions: Persistent AF shows organized islands of synchronized electrograms, whose size and duration predict the likelihood of termination by ablation. Future studies should investigate the pathophysiology of synchronized islands in AF.

Chemodectoma located in the left atrium in 11 month survival dog with the use of palliative therapy

The aim of this study was to present a clinical case of chemodectoma located in the left atrium in a dog. Chemodectoma is a heart base tumor, neoplasms that occur in the proximity of major blood vessels. A presumptive diagnosis is made based on location and appearance of the tumor in echocardiography examination. In advanced diagnostics computed tomography (CT) and magnetic resonance imagining (MRI) are used. Final diagnosis is made mainly during autopsy based on histopatological examination or less commonly in veterinary medicine on a histopathological examination of the tissue taken during a biopsy or of the entire removed tumor. In literature few methods of treatment are presented, including surgery, chemotherapy and radiotherapy. In an 8-year-old male French bulldog a tumor in the left atrium was detected. The tumor filled almost the entire left atrium, additionally pericardial effusion and ascites were observed. For treatment, tarantula cubensis extract (Theranecron) was used. After the introduction of Theranecron the patient felt significantly better. Theranecron may be one of the possibilities of palliative therapy in the case of diagnosing inoperable chemodectoma.

An Image-based Approach for 3D Left Atrium Functional Measurements.

There is growing interest in the assessment of function of the left atrium (LA) in patients with atrial fibrillation (AF). Existing methods of LA functional measurement only quantify a limited subset of the functional parameters from a single or biplane CINE-MRI scan through the LA. Here, we propose an image-based method for comprehensive evaluation of the function of the entire LA in 3D. 4D LA images were reconstructed from a series of CINE image stack covering the whole LA with small or no gap between thin slices. A segmentation from a high-resolution Magnetic Resonance Angiography (MRA) was registered and propagated through pairwise deformable registrations covering the cardiac cycle. Volume, LA ejection fraction and surface strain were computed for each timepoint and registered to Late Gadolinium Enhancement (LGE) scans for each of 52 patient scans. A correlation coefficient of -0.11 was calculated between LGE and strain, indicating that fibrotic tissue correlates with reduced elasticity.

Abstract 262: Regional Transcriptomics of Left Atrial Cardiac Tissue in a Patient With Atrial Fibrillation

Background: Common genetic variants and inflammatory factors are associated with atrial fibrillation (AF) risk. Although the top AF risk locus is near PITX2 (associated with pulmonary vein (PV) development), regional differential expression (DE) of AF risk genes in the left atrium (LA) and PVs is not well studied. While LAA and PV gene expression have been compared, transcriptome mapping of the entire LA has not been done. We tested the hypothesis that there is significant regional DE in LA structures. Methods: RNAseq was performed in 25 regions within the PVs (n=12), LA body (LAB) (n=10), and LA appendage (LAA) (n=3) from a 75 year old male with hypertension and AF who died of a stroke. DE analysis of regional clusters (R 3.6 Limma package) and gene set enrichment analysis (GSEA) (Broad Institute) were performed. Results: In full transcriptome (n=20664) sequencing, 118 genes were significantly (q &lt; 0.05) upregulated in the LAA, including FOSB (fold change [FC] 67.0), IL6 (FC 15.4), TNF (FC 2.4) and NLRP3 (FC 2.4), and 56 downregulated, including developmental genes such as SHOX2 (FC -12.9) and HOXA4 (FC -4.1). LAA GSEA showed enrichment (FDR &lt; 0.05) of inflammatory response genes and TNF-α, IL-2, IL-6, and IgG signaling pathways. 2454 genes were significantly upregulated and 3737 downregulated in the PVs while 4021 genes were upregulated and 2998 were downregulated in the LAB. In an AF implicated gene set (n=190), 28 genes were upregulated in the PVs, including SIRT1 (FC 1.7), and 31 downregulated, including PMNT (FC -2.1) and CGA (FC -3.2). NEURL1 was significantly upregulated in the inferior PV (n=4) compared to the superior PV (n=8) (FC 3.6). In the LAB, 33 genes were upregulated, including MYH7 (FC 2.2) and PMNT (FC 2.1) , and 38 downregulated including SIRT1 (FC -1.9). PITX2 did not show any significant DE in any gene set. Conclusions: This data shows that genes involved in AF pathogenesis can have substantial regional expression difference, particularly when comparing the LA body, PVs, and LAA. Inflammatory activation in the LAA may contribute to increased stroke risk.

Strain maps of the left atrium imaged with a novel high-resolution CINE MRI protocol.

To date, regional atrial strains have not been imaged in vivo, despite their potential to provide useful clinical information. To address this gap, we present a novel CINE MRI protocol capable of imaging the entire left atrium at an isotropic 2-mm resolution in one single breath-hold. As proof of principle, we acquired data in 10 healthy volunteers and 2 cardiovascular patients using this technique. We also demonstrated how regional atrial strains can be estimated from this data following a manual segmentation of the left atrium using automatic image tracking techniques. The estimated principal strains vary smoothly across the left atrium and have a similar magnitude to estimates reported in the literature.

A novel approach to mapping the atrial ganglionated plexus network by generating a distribution probability atlas.

IntroductionThe ganglionated plexuses (GPs) of the intrinsic cardiac autonomic system are implicated in arrhythmogenesis. GP localization by stimulation of the epicardial fat pads to produce atrioventricular dissociating (AVD) effects is well described. We determined the anatomical distribution of the left atrial GPs that influence atrioventricular (AV) dissociation.Methods and ResultsHigh frequency stimulation was delivered through a Smart‐Touch catheter in the left atrium of patients undergoing atrial fibrillation (AF) ablation. Three dimensional locations of points tested throughout the entire chamber were recorded on the CARTO™ system. Impact on the AV conduction was categorized as ventricular asystole, bradycardia, or no effect. CARTO maps were exported, registered, and transformed onto a reference left atrial geometry using a custom software, enabling data from multiple patients to be overlaid. In 28 patients, 2108 locations were tested and 283 sites (13%) demonstrated (AVD‐GP) effects. There were 10 AVD‐GPs (interquartile range, 11.5) per patient. Eighty percent (226) produced asystole and 20% (57) showed bradycardia. The distribution of the two groups was very similar. Highest probability of AVD‐GPs (>20%) was identified in: inferoseptal portion (41%) and right inferior pulmonary vein base (30%) of the posterior wall, right superior pulmonary vein antrum (31%).ConclusionIt is feasible to map the entire left atrium for AVD‐GPs before AF ablation. Aggregated data from multiple patients, producing a distribution probability atlas of AVD‐GPs, identified three regions with a higher likelihood for finding AVD‐GPs and these matched the histological descriptions. This approach could be used to better characterize the autonomic network.

Homeostatic Left Heart integration and disintegration links atrio-ventricular covariation\u2019s dyshomeostasis in Hypertrophic Cardiomyopathy

Left ventricle and left atrium are and have been practically always analyzed separately in common clinically and non-clinically oriented cardiovascular investigations. Both classic and speckle tracking echocardiographic data contributed to the knowledge about deformational impairments occurring in systo-diastolic differences. Recently new trajectory based approaches allowed a greater awareness about the entire left ventricle or left atrium revolution and on their deficiencies that take place in presence of hypertrophic cardiomyopathy. However, surprisingly, the concomitant function of the two left heart chambers has not been analyzed for their geometrical/mechanical relationship. For the first time we study here, by acquiring left ventricle and left atrial geometries on the same heartbeat, the trajectory attributes of the entire left heart treated as a whole shape and the shape covariation of its two subunits. We contrasted healthy subjects with patients affected by hypertrophic cardiomyopathy. We found impaired left heart trajectory mainly in terms of orientation and size. More importantly, we found profound differences in the direction of morphological covariation of left ventricle and left atrium. These findings open to new perspectives in pathophysiological evaluation of different diseases by allowing the appreciation of concomitant functioning of both left heart whole geometry and of its two chambers.

Propagation of meandering rotors surrounded by areas of high dominant frequency in persistent atrial fibrillation

Identification of arrhythmogenic regions remains a challenge in persistent atrial fibrillation (persAF). Frequency and phase analysis allows identification of potential ablation targets. This study aimed to investigate the spatiotemporal association between dominant frequency (DF) and reentrant phase activation areas. A total of 8 persAF patients undergoing first-time catheter ablation procedure were enrolled. A noncontact array catheter was deployed into the left atrium (LA) and 2048 atrial fibrillation electrograms (AEGs) were acquired for 15 seconds following ventricular far-field cancellation. DF and phase singularity (PS) points were identified from the AEGs and tracked over consecutive frames. The spatiotemporal correlation of high DF areas and PS points was investigated, and the organization index at the core of high-DF areas was compared with that of their periphery. The phase maps presented multiple simultaneous PS points that drift over the LA, with preferential locations. Regions displaying higher PS concentration showed a degree of colocalization with DF sites, with PS and DF regions being neighbors in 61.8% and with PS and DF regions overlapping in 36.8% of the time windows. Sites with highest DF showed a greater degree of organization at their core compared with their periphery. After ablation, the PS incidence reduced over the entire LA (36.2% ± 23.2%, P < .05), but especially at the pulmonary veins (78.6% ± 22.2%, P< .05). Multiple PS points drifting over the LA were identified with their clusters correlating spatially with the DF regions. After pulmonary vein isolation, the PS's complexity was reduced, which supports the notion that PS sites represent areas of relevance to the atrial substrate.

The Efficacy of Multipolar Basket Catheters in Mapping the Entire Left Atrium in Human Persistent Atrial Fibrillation

The Efficacy of Multipolar Basket Catheters in Mapping the Entire Left Atrium in Human Persistent Atrial Fibrillation

Is It Necessary to Achieve a Complete Box Isolation in the Case of Frequent Esophageal Temperature Rises? Feasibility of Shifting to a Partial Box Isolation Strategy for Patients With Non-Paroxysmal Atrial Fibrillation.

There are some cases with frequent luminal esophageal temperature (LET) rises despite titrating the radiofrequency energy while creating a linear lesion for the Box isolation of atrial fibrillation (AF). Little is known about the feasibility of redesigning the ablation lines for a modified Box isolation strategy to prevent fatal esophageal injury in those cases. Two hundred and seventeen patients who underwent a Box isolation of non-paroxysmal AF were evaluated. We divided them into 2 groups, patients in whom a box lesion set of the entire posterior left atrium had been achieved (complete Box isolation [CBI]; n = 157) and those in whom 2 additional peri-esophageal vertical lines were created at both the right and left ends of the esophagus, and those areas were left with an incomplete isolation when frequent rapid LET rises above 39.0 °C were observed while creating the floor line (partial Box isolation [PBI]; n = 60). During 20.1 ± 13.9 months of follow-up, the arrhythmia-free rates were 54.1% in the CBI group versus 48.3% in the PBI group (P = 0.62). In the second session, a complete Box isolation was highly achieved even in the PBI group (94.3% vs. 83.3%, respectively; P = 0.17) and after 2 procedures, the arrhythmia-free rates increased to 75.2% vs. 68.3%, respectively (P = 0.34). There was no symptomatic esophageal injury in the PBI group. In the case of frequent LET rises while creating the linear lesions for the Box isolation strategy for non-paroxysmal AF, shifting to the PBI strategy was feasible.

Bipolar Sealing of Lung Veins with 5 mm and 10 mm Instruments - Bursting Pressures Measured in an Ex-Vivo Model

In every anatomic lung resection, lung veins need to be sealed and divided. If open surgery is performed, veins are usually treated with ligatures. In minimally-invasive procedures a vascular stapler is used. Blood vessels can be securely closed with modern bipolar sealing technology. Since this method has rarely been used in lung veins, we carried out the present study on an ex-vivo model to test whether satisfactory bursting pressures can be achieved using 5 mm and 10 mm MARSEAL® sealing instruments. The experimental investigations were carried out on heart-lung preparations (including both lungs) from freshly-slaughtered pigs (weight: 199 lbs). After the lung veins were dissected, three groups were formed according to size: group 1: 1-7 mm, group 2: 8-10 mm and group 3: > 10 mm. Bipolar sealing was performed with a 5 mm or 10 mm MARSEAL® sealing device and the special SealSafe® G5 electric current. Vessels closed by simple ligation served as a control group. A pressure sensor was implanted into the unsealed end of the blood vessel. Air was pumped into the blood vessel and the bursting pressure - the pressure (in mbar) at which the vessel began to leak - was determined digitally. The mean bursting pressures were compared using the non-parametric Mann Whitney U test (the level of significance was p < 0.05). In group 1 the mean bursting pressures for the 5 mm and 10 mm instruments were found to be 167.1 ± 38.7 mbar and 113.8 ± 23.3 mbar, respectively. Both were significantly inferior to the pressure of 178.8 ± 44.5 mbar achieved by the control group. In group 2 the bursting pressures were 122.7 ± 27.8 mbar with the 5 mm instrument and 93.5 ± 39.6 mbar with the 10 mm instrument. The mean bursting pressure for the control group was 180.7 ± 35.8.mbar. In group 3 the mean bursting pressures were 98.2 ± 28.8 mbar with the 5 mm instrument and 65.5 ± 19.7 mbar with the 10 mm instrument. All attempts to seal the entire left atrium failed. In our ex-vivo model of lung veins, acceptable bursting pressures were achieved in blood vessels with a maximum diameter of 10 mm. Bipolar impedance-controlled sealing may create an adequate seal on pulmonary veins up to a diameter of 10 mm. The use of a 10 mm instrument has no advantage compared to a 5 mm instrument. Secure sealing of the left atrium is not possible.

Abstract 16342: Feasibility and Safety of Intra-operative Mapping for Diagnosis of the Substrate of Atrial Fibrillation

Introduction: Multi-site, high-resolution mapping can be used to identify either the trigger or substrate perpetuating atrial fibrillation (AF). The goal of this study was to assess the feasibility and safety of a new high-resolution epicardial mapping approach. Hypothesis: Epicardial atrial mapping of the entire atria can be safely performed as a routine procedure during cardiac surgery. Methods: Epicardial mapping of the entire right atrium, left atrium and Bachmann’s Bundle was performed in 291 patients (218 male, age:66±11yrs) undergoing elective surgery during sinus rhythm (SR) and (induced) AF using high-resolution mapping arrays with inter-electrode distances of 1-2mm. Electrophysiological parameters were quantified and designated to anatomical quadrants of 1cm2. Results: AF was non-inducible in 36 patients. Hemodynamic parameters (mean arterial pressure, right atrial pressure, BIS score, ST-T segment alterations) before and during SR mapping were comparable (P&lt;0.22). During AF, only mean arterial pressure (71±11 versus 67±10mmHg (P&lt;0.004)) and right atrial pressure (10±4 versus 11±4mmHg (P&lt;0.0001)) decreased. Total mapping time during SR or AF was respectively 3±1min. and 4±2min. Beat-to-beat variation of SR cycle length and peak-to-peak amplitude of unipolar potentials were respectively 0.04±14.42ms and -0.01±0.53mV, reflecting stability of the mapping array. Complications were not observed. Conclusions: Our novel intra-operative epicardial atrial mapping approach can be safely applied during both SR and AF. This mapping approach is the first technique allowing quantification of the arrhythmogenic substrate in the individual patient thereby taking the first step towards personalizing treatment of AF.

Restoration of sinus rhythm and atrial transport function after the maze procedure: U lesion set versus box lesion set

ObjectiveIn a U lesion set, the left atrium (LA) roof between the right and left superior pulmonary veins is not ablated, to allow activation to propagate across the posterior LA and to recruit this segment as a contractile atrial component. In contrast, the box lesion set isolates the entire posterior LA. MethodsTo compare the two lesion sets, postoperative freedom from atrial fibrillation (AF) and LA transport function were examined in 402 patients who underwent surgery for AF with a U lesion (n = 329) or box lesion (n = 73) set. Patients who underwent pulmonary vein isolation alone or other simplified procedures were excluded from the study. LA transport function was quantified at 20 ± 33 months postoperatively by the ratio of peak velocity of the A wave to the E wave (peak A/E) of the transmitral Doppler flow. ResultsIn patients with long-standing persistent AF, freedom from AF was 85% with the U lesion set and 77% with the box lesion set at 5 years after the maze procedure, and 82% and 77%, respectively, at 10 years after the procedure. There was no significant difference between the U lesion set and box lesion set in patients with long-standing persistent AF (P = .30) and those with paroxysmal or persistent AF (P = .90). Proportional hazards analysis identified increased LA diameter (P = .003) and long-standing persistent AF (P = .03), but not the type of lesion set (P = .51), as predictive of postoperative AF recurrence. The postoperative peak A/E was significantly greater after the U lesion set than after the box lesion set (0.42 ± 0.22 vs 0.23 ± 0.17), and multiple regression analysis demonstrated that the type of lesion set and preoperative LA diameter significantly affected postoperative A/E. ConclusionsThe U lesion set restores sinus rhythm frequently as the box lesion set and provides better LA transport function. A dilated LA is a risk factor for postoperative recurrence of AF and poor postoperative LA transport function.