Left Atrial Max Research Articles

LA workflow recommendations for intracardiac echocardiography integration with artificial intelligence 3D algorithm

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The creation of an artificial intelligence imaging algorithm, the CARTOSOUND FAM Module, shows promise in enhancing current intracardiac echocardiography (ICE) practices, particular in atrial fibrillation (AF) ablation. However, there is a gap of knowledge associated with how to best optimize current practices. This study aims to provide workflow recommendations based on a high-volume US center. Methods The CARTOSOUND FAM Module is an automated version of the legacy CARTOSOUND Module. It incorporates an automatic algorithm that enables automatic detection of cardiac anatomy using a series of 2D ultrasound views. The left atrial (LA) algorithm uses a series of 2D ultrasound frames acquired from the right atrium (RA)/fossa ovalis and the RVOT to: create a 3D volume reconstruction of the LA anatomies (LA Body, LAA, LSPV, LIPV, RSPV, and RIPV), provide 3D auto-segmentation for the relevant anatomical structures, generate 2D auto-contours that are overlaid on the corresponding 2D ultrasound frames, and demonstrate 2D auto-tagging for the relevant anatomical structures. Best practice recommendations have been collected and summarized. Results The required input for the CARTOSOUND FAM algorithm: 2D ULS distinct frames, with full spatial coverage of the LA body and its adjacent key anatomical structures (LAA and PVs), with at least 2 different views for each structure, and preferably clearly visualizing the ostium of the PV’s and LAA. The 2D clips should be acquired while the SOUNDSTAR® catheter is positioned in the RA and/or the RVOT. The selected frames within the ULS clip should be gated at the end-expiration phase and to the LA max volume (). LA frames with a temporal resolution of ~20 msec just before the opening of the mitral valve at the time of maximal atrial volume (end atrial diastole). The selected frames within the ULS clip should be with depth 90-140mm. The LA anatomy shall not have uncommon anatomical variation (e.g. 5th PV). There shall be no map shift between the ULS data (frames) and the magnetic data (FAM, VISITAGs, EA points, etc.) in the CARTOSOUND® clinical procedure. Conclusion This study successfully reports on best workflow practices in using the CARTOSOUND FAM Module in conjunction with ICE. Further studies evaluating the safety and efficiency are required to validate reproducibility these recommendations.

FEV1 is independently related with impaired left atrial strain in chronic obstructive pulmonary disease patients: A speckle tracking study.

Atrial fibrillation (AF) is common in chronic obstructive pulmonary disease (COPD) patients. It is known that impaired forced expiratory volume in 1s (FEV1) is one of the risk factors of cardiovascular disease. Two-dimensional speckle tracking echocardiography (2D-STE) can detect deterioration of left atrial mechanical functions in the subclinical stage. We hypothesized that reduced lung functions, measured by FEV1 in COPD patients, may be associated with impaired left atrial (LA) mechanical functions. Present study included 127 consecutive COPD patients. We divided study population into two groups: patients with normal LA strain (n = 20) or with impaired LA strain (n = 107). In univariate logistic regression analysis, age (p: 0.001), FEV1% (p < 0.001), FEV1 (p < 0.001), FEV1/forced vital capacity (FVC) (p: 0.014), white blood cell (p: 0.012), LA Max vol (p: 0.026), C-reactive protein (p :0.001), arterial oxygen pressure (PaO2 ) (p: 0.019), arterial oxygen saturation (SO2 ) (p: 0.021), left ventricle ejection fraction (LVEF) (p: 0.042), and mitral A-wave velocity (p: 0.017) were associated with impaired LA-strain. In multivariate logistic regression analysis, age (p: 0.043), FEV1 (p < 0.001), LA Max vol (p: 0.004), and LVEF (p: 0.004) were independently associated with impaired LA strain. FEV1 is associated with impaired left atrial strain independently of arterial blood gas and left ventricular diastolic dysfunction parameters in COPD patients with preserved left ventricular systolic function.

Impaired left atrial mechanical functions as indicators for increased aortic root diameter in hypertensive and diabetic patients.

Previous studies have demonstrated that increased aortic root diameter (ARD) is frequently associated with increased cardiovascular (CV) events and is apredictor of stroke. Two-dimensional speckle tracking echocardiography (2D-STE) provides abetter evaluation of left atrial (LA) functions. Left atrial mechanical dispersion is auseful predictor of new-onset atrial fibrillation (AF) independent of LA enlargement and dysfunction. We aimed to investigate the relationship between ARD and LA mechanical functions. The present study included 93consecutive patients with hypertension and diabetes. The relationships between ARD and LA functions was evaluated. Study population was divided into two groups according to the mean ARD values: group1 (ARD ≤30.03 mm, n = 53) and group2 (ARD >30.03 mm, n = 40). In group2, age, LA maxvolume (vol), LA preA vol, LA min vol, LA emptying fraction, LA active ejection fraction (EF), and LA expansion index were significantly higher compared to group1. S‑LAs and SR-LAs (peak LA strain and strain rate, respectively, during ventricular systole) and S‑LAe and SR-LAe (peak early diastolic LA strain and strain rate, respectively) were significantly lower in group2 compared to group1. Age, LA max vol, LA preA vol, LA min vol, LA emptying fraction, LA active EF, LA expansion index, S‑LAs, S‑LAe, SR-LAs, and SR-LAe were significantly associated with increased ARD. In multivariate logistic regression analysis, age, LA expansion index, and SR-LAe were independent predictors for ARD. Impaired LA mechanical functions determined by speckle tracking methods are related with increased ARD independent of LV diastolic dysfunction.

The effect of pulmonary arterial hypertension specific treatment on the left ventricle in patients with pulmonary arterial hypertension

Abstract Background Pulmonary arterial hypertension (PAH) is characterized by right ventricular (RV) pressure overload, leading to RV dilation, failure and death. In the course of the disease, the left ventricle (LV) is often impaired, due to interventricular interaction. Although the impact of PAH treatment on the RV has been well described, less is known on the LV. Purpose To examine effects of advanced PAH treatments on the volumes, function and strain of the left atrium and ventricle. Methods This is a retrospective study. All patients underwent CMR and right heart catheterization, both at diagnosis and at 12-months follow up. Ventricular volumes and LV filling rate were calculated from the stack of short axis cine images using Simpsons method while left atrial (LA) volumes from the 4-chamber cine images using the area-length method. Tissue tracking was used for the evaluation of myocardial deformation. The LV endocardial and epicardial borders were manually delineated in all analysed sections with the initial contour set at end-diastole. All analyses were performed offline using dedicated software. Results In total, 66 patients (mean age 56.3±17.9 years, 67%women, 77%idiopathic and heritable PAH, 23% connective tissue disease associated PAH) and 29 normal controls were included. The improvement in metrics of right and left heart size and function after the initiation of advanced PAH treatment, are presented in panel A. Of note, LV stroke volume was markedly increased (54.6±19.6ml at baseline vs 70.8±21.7ml at follow up, p&amp;lt;0.0001) to reach controls. LV filling was markedly increased in latter two-thirds of the diastolic phase (panel B), especially at atrial kick point (arrow). Change in LA max volume was associated with changes in diastolic filling (r=0.354, p=0.004), LV end-diastolic and end-systolic volumes and stroke volume. These correlations were more robust in patients that increased LV filling compared to those that failed to increase LV filling (panels C-E). No association between changes in LV circumferential strain and LV volume load was observed. A weak correlation of change of LV peak longitudinal strain with stroke volume (r=−0.345, p=0.006), LV end diastolic volume (r=−0.284, p=0.027), LV ejection fraction (r=−0.337, p=0.008) and LA maximum area (r=−0.447, p&amp;lt;0.0001) was observed. The changes of LV strain showed no correlation with the changes in patients' haemodynamics. Conclusion Improvement in stroke volume after the initiation of advanced PAH treatment is associated with an increase in LA size, LV end diastolic volume and normalisation of strain. This reflects the improved filling state of the left ventricle and the potential of the left atrium to monitor treatment effects. Changes after PAH treatment Funding Acknowledgement Type of funding source: None

1039 Time course of left atrial performance in patients with paroxysmal atrial fibrillation undergoing radio-frequency catheter isolation of pulmonary veins

Abstract Background Radio-frequency catheter isolation of pulmonary veins (RF-PVI) is associated with changes of left atrial (LA) structure and function. However, there is limited knowledge regarding the long-term impact of successful RF-PVI on the LA mechanics. The aim of the current study was to assess the time course of LA performance in patients with paroxysmal atrial fibrillation (pAF) undergoing RF-PVI. Methods The study population included 24 consecutive patients (age:62 ± 21 years; 66% male) with symptomatic pAF and preserved left ventricular ejection fraction (≥50%) undergoing the first RF-PVI and 23 healthy controls. A comprehensive echocardiographic examination was performed one day before and 1 day, 3- and 12- months after RF-PVI. The reservoir, conduit and contractile LA strain (LAS), strain rate (LASR) and mechanical dispersion (LAMD) were assessed using two-dimensional speckle tracking echocardiography in apical views. Results At baseline, patients with pAF showed a significant reduction of all three components of LAS and LASR compared with controls (all p &amp;lt; 0.01). At 1 day after RF-PVI, LAS and LASR showed significant decrease compared with baseline (all p &amp;lt; 0.05) (figure). At 3-month follow up, LAS and LASR recovered to baseline values while LAMD showed a significant improvement (77ms vs 58ms, p = 0.003). At 12-month follow up, both reservoir and contractile LAS showed further improvement compared to 3-month values (31% vs 27%, and 15% vs 13%, both p &amp;lt; 0.05). Yet, even after 12 months, LAS values remained significantly lower compared with healthy controls (p &amp;lt; 0.05). LA emptying fraction was restored and LA end-systolic (max) and end-diastolic (min) volume index showed a significant decrease compared to baseline and 3-month values (all p &amp;lt; 0.05). Conclusion Successful RF-PVI is associated with acute decrease in LAS, followed by recovery to baseline values within 3 months and further improvement during one year. Reservoir and contractile LAS appears to be the most clinically useful indices to monitor LA performance in patients with pAF undergoing RF-PVI. Figure Time course of LA reservoir and contractile strain, LA max and min volume index, and LA mechanical dispersion (Baseline, 1-day FUP, 3- and 12-month FUP). Abstract 1039 Figure.

072 Altered LA Strain in Bone Marrow Transplant (BMT) Patients Previously Treated With Anthracyclines: A Marker of an Atrial Myopathy

Strain analysis by echocardiography can help identify patients with subclinical left atrial (LA) impairment, which may help predict future cardiac dysfunction and arrhythmias. 30 BMT patients with prior anthracycline (AC) exposure as part of their chemotherapy regimen, who underwent transthoracic echocardiogram (TTE) between November 2016 and September 2017 were included. They were compared to 30 age and gender matched controls from a departmental database. Normal left ventricular (LV) global longitudinal strain (GLS) was defined as >17%. Strain analysis was performed using GE Echopac. Mean time from BMT to TTE was 7 years. There was no significant difference in LVEF between groups. In the presence of reduced LV GLS, LA reservoir, contractile and conduit strain, were significantly reduced. The LA volume was significantly increased in the BMT groups compared to controls. All phasic LA strain were reduced in the presence of subclinical LV dysfunction. This may represent a coexistent atrial myopathy in the context of AC exposure. Further analysis is ongoing to explore the potential clinical implications of subclinical LA dysfunction in the BMT population.Tabled 1BMT + ACControlsp value*Normal GLSReduced GLSN181230LV EF (%)60±654±357±90.075LV GLS (%)20±214±219±20.001LA max volume (indexed, ml/m2)29±332±225±50.026LA reservoir strain33±923±335±80.001LA contractile strain17±613±317±50.008LA conduit strain17±910±417±70.007*Kruskal-Wallis Open table in a new tab

PP.36.23

Objective: Arterial hypertension (AH) leads to left atrial (LA) dilation, that could be a substrate for the occurrence of atrial fibrillation (AF) and associated with the LA remodeling. Aim of the study was to determine if the short-standing paroxysmal AF influences on structural and functional disorders of LA in patients (pts) with AH. Design and method: 74 hypertensive pts (age 63,0 ± 9,5 years; 40% male) were divided into 2 comparable groups: 44 pts with paroxysmal AF of less than 1 year arrhythmic anamnesis and paroxysms frequency 1 per 3 months (G1), 30 pts without AF (G2). Echocardiography with Doppler technique and ABPM were performed. LA enlargement was defined as LA volume index (LAVI) > 29 mL/m2. LA empting fraction (LAEF) < 45% and LA expansion index (LA exp inx) < 90% were categorized as LA phasic dysfunction. Results: LAVI was significantly higher in G1 vs G2 group [32,1 (28,3; 35,7) vs 24,7 (23,2; 27,2) mL/m2, p < 0.0001]. 23 (52%) pts in G1 and 12 (40%) pts in G2 had LAVI > 29 mL/m2(p = 0.02). LAEF was comparable in G1 and G2 [46,9 (46; 48) vs 45,9% (45,3; 46,6)] as well as reduced LAEF [9 (19%) vs 9 (26%) pts]. LA exp inx was significantly higher in G1 [88,5 (85,3; 92,3) vs 85,1% (82,8; 87,3), p = 0,004]. Decreased LA exp inx was observed more frequently in G2 than in G1 group [24 (80%) vs 20 (46%) pts, p = 0,003]. In G1 group LAVI significantly (p < 0.05) correlated with LA size (r = 0,65), MMI and E/e’ (r = 0,37 for both cases). LAEF and LA exp inx correlated with mean day DBP (r = −0,57), min day SBP (r = −0,46) and max day HR (r = −0,50). There was significant correlation LAVI with LA size (r = 0,57), MMI (r = 0,42), mean night systolic (r = 0,81) and diastolic (r = 0,76) BP in G2 group. Conclusions: LA structure was greater abnormal in hypertensive pts with AF compared to pts without arrhythmia. Short-standing paroxysmal AF did not significantly influence on LA function in pts with AH. LA structure and function correlated with BP level. Negative correlation between LA exp inx and max day HR was additionally found for hypertensive pts with AF.

Left atrial size and function as predictors of new-onset of atrial fibrillation in patients with asymptomatic aortic stenosis: The simvastatin and ezetimibe in aortic stenosis study

Left atrial (LA) size and function change with chronically increased left ventricular (LV) filling pressures. It remains unclear whether these variations in LA parameters can predict new-onset atrial fibrillation (AF) in asymptomatic patients with aortic stenosis (AS). Data were obtained in asymptomatic patients with mild-to-moderate AS (2.5 ≤ transaortic Doppler velocity ≤ 4.0m/s), preserved LV ejection fraction (EF), no previous AF, and were enrolled in the Simvastatin and Ezetimibe in Aortic Stenosis study. Peak-aortic velocity, LA(max) volume & LAmin volume were measured by echocardiography. LA conduit (LA(con)) volume was defined as LV stroke volume-LA stroke volume. LA function was expressed as LA-EF (LA(max)-LAmin volume/LA(max)). In the 1159 patients included, new-onset AF occurred in 71 patients (6.1%) within a mean follow-up of 4.2 ± 0.9 years. Mean age was 66 ± 9.7 years, aortic valve area index 0.6 ± 0.2 cm(2)/m(2), LV mass 99.2 ± 29.7 g/m(2), LA(max) volume 34.6 ± 12.0 mL/m(2), LAmin volume 17.9 ± 9.3 mL/m(2), LA-EF 50 ± 15% and LA(con) volume 45 ± 21 mL/m(2). Baseline LAmin volume predicted new-onset AF in Cox multivariable analysis (HR:2.3 [95%CI:1.3-4.4], P<0.01), and added prognostic information on AF development beyond conventional risk factors (likelihood ratio, P<0.01). In comparison of c-indexes LAmin volume was superior to all other LA measurements. Net reclassification index improved by 15.9% when adding LAmin volume to a model with classic risk factors for AF (P=0.01). LAmin volume independently predicted new-onset AF in patients with asymptomatic AS and was superior to LA-EF, LA(con) and LA(max) volumes and conventional risk factors.

Early Left Atrial Mechanics and Volume Abnormalities in Subjects with Prehypertension: A Real Time Three-Dimensional Echocardiography Study

The aim of this study was to evaluate left atrial (LA) volume and mechanical functions by real time three-dimensional echocardiography (RT3DE) in prehypertensive subjects. The study included 54 (34 male and 20 female) prehypertensive subjects and 36 (14 male and 22 female) healthy control subjects. Transthoracic echocardiography and RT3DE were performed in all patients. Interventricular septum thickness and isovolumetric relaxation time were significantly higher in prehypertensives than in controls (10.7 ± 0.7 vs. 10.1 ± 0.8 P = 0.001 and 89.9 ± 10 vs. 82.4 ± 11 P = 0.002, respectively). LA maximum volume, volume before atrial contraction, total and active stroke volume, total and active emptying fractions, expansion index, and LA max volume index were significantly higher in prehypertensives when compared with controls (P < 0.0001 for all). However, the passive emptying fraction was significantly lower in prehypertensives than controls (45.7 ± 5.6 vs. 48.6 ± 4.1, P = 0.006), and the minimum LA volume between the two groups was similar. The main finding of this study was that although LA volume and LA active systolic functions were significantly increased in prehypertensive people, there was a reduction in passive LA systolic functions. These parameters may be important in showing hemodynamic and structural changes in cardiac tissue caused by prehypertension.

Abstract 8696: Assessment of Time-Left Atrial Volume Curve and Left Atrial Emptying Function by Speckle Tracking Echocardiography is Useful to Evaluate Left Ventricular Diastolic Function in Patients with Preserved Ejection Fraction

Background: Left atrial (LA) volume is proposed to evaluate left ventricular (LV) filling pressure and E/e' is used to estimate LV diastolic function instead of invasive measurement. However, it is difficult to measure LA volume accurately and quickly using routine echocardiography and E/e' from 8 to 15 is classified as a gray zone to estimate LV filling pressure. Thus, we assessed the hypothesis that evaluation of time-LA volume curve and LA emptying function (EF) measured by speckle tracking may be more useful to estimate LV diastolic function as a noninvasive method in the clinical settings than E/e' . Methods : LA phasic volume and EF were measured in 34 patients (age 69±8, 14 men) with LV ejection fraction ≥50% by speckle tracking echocardiography that can provide time-LA volume curve automatically, and E/e' was also obtained just before cardiac catheterization, and these parameters were compared with pulmonary capillary wedge pressure (PCWP). Results : LA max. and min. volume had significant positive correlations with PCWP (r=0.72, P&lt;0.01 and r=0.80, P&lt;0.01, respectively). LA total, passive and active EF had significant negative correlations with PCWP (r=-0.82, p&lt;0.01, r=-0.56, p&lt;0.05 and r=-0.66, P&lt;0.01, respectively). There was a significant but weak positive correlation between E/e' and PCWP (r=0.52, p&lt;0.05). As PCWP was elevated, LA max. and min. volume were increased and pre-atrial contraction volume was closer to min. volume, and total and active EF were decreased (Figure). Using 33% of LA total EF as a cutoff, the sensitivity and the specificity in predicting elevated LV filling pressure &gt;12mmHg were 89% and 88%, while using 15 of E/e' those values were 53% and 79%, using 40ml/m 2 of LA volume those values were 48% and 82%. Conclusions : In noninvasive estimation of LV diastolic function, assessment of time-LA volume curve and LA EF may be a novel and more useful method and have an incremental value compared with measurement of LA volume and E/e' in the clinical settings .

Assessment of left atrial volume and function: a comparative study between echocardiography, magnetic resonance imaging and multi slice computed tomography

Measurement of left atrial (LA) maximal volume (LA(max)) using two-dimensional transthoracic echocardiography (TTE) provides prognostic information in several cardiac diseases. However, the relationship between LA(max) and LA function is poorly understood and TTE is less well suited for measuring dynamic LA volume changes. Conversely, cardiac magnetic resonance imaging (CMR) and multi-slice computed tomography (MSCT) appears more appropriate for such measures. We sought to determine the relationship between LA size assessed with TTE and LA size and function assessed with CMR and MSCT. Fifty-four patients were examined 3 months post myocardial infarction with echocardiography, CMR and MSCT. Left atrial volumes and LA reservoir function were assessed by TTE. LA time-volume curves were determined and LA reservoir function (cyclic change and fractional change), passive emptying function (reservoir volume) and pump function (left atrial ejection fraction-LAEF) were derived using CMR and MSCT. Left atrial fractional change and left atrial ejection fraction (LAEF) determined with CMR and MSCT were unrelated to LA(max) enlargement by echocardiography (P = NS). There was an overall good agreement between CMR and MSCT, with a small to moderate bias in LA(max) (4.9 ± 10.4 ml), CC (3.1 ± 9.1 ml) and reservoir volume (3.4 ± 9.1 ml). TTE underestimates LA(max) with up to 32% compared with CMR and MSCT (P < 0.001). Left atrial function assessed with MSCT and CMR as LA fractional change and LAEF is not significantly related to LA(max) measured by TTE. TTE systematically underestimated LA volumes, whereas there are good agreements between MSCT and CMR for volumetric and functional properties.

Functional assessment of the left atrium by real-time three-dimensional echocardiography using a novel dedicated analysis tool: initial validation studies in comparison with computed tomography

A novel real-time three-dimensional echocardiography (RT3DE) analysis tool specifically designed for evaluation of the left atrium enables comprehensive evaluation of left atrial (LA) size, global, and regional function using a dynamic 16-segment model. The aim of this study was the initial validation of this method using computed tomography (CT) as the method of reference. The study population consisted of 34 prospectively enrolled patients with clinical indication for pulmonary vein isolation. A dynamic polyhedron model of the left atrium was generated using RT3DE. LA maximum and minimum volumes (LA(max)/LA(min)) and emptying fraction (LAEF) were determined and compared with the results obtained by CT. High correlations between RT3DE and CT were found for LA(max) (r = 0.92, P < 0.001), LA(min) (r = 0.95, P < 0.001), and LAEF (r = 0.82, P < 0.001). LA(max) and LA(min) were lower by RT3DE than by CT (95.0 ± 44.7 vs. 119.8 ± 50.5 mL, P < 0.001 and 58.1 ± 41.3 vs. 83.3 ± 52.6 mL, P < 0.001, respectively), whereas LAEF was measured higher by RT3DE (42.8 ± 15.2 vs. 34.2 ± 15.4%, P < 0.001, respectively). RT3DE measurements closely correlated in terms of intra-observer (intra-class correlation r = 0.99, r = 0.99, r = 0.96, respectively) and inter-observer variability (r = 0.97, r = 0.98, r = 0.88, respectively). LA volumes and EF as assessed by RT3DE correlate highly with CT measurements, albeit there is some bias between the imaging modalities. Most importantly, RT3DE measurements using the novel dedicated LA analysis tool are robust in terms of observer variability and thus suitable for follow-up analyses.

Left Atrial Mechanical Responses to Right Ventricular Pacing in Heart Failure Patients: Implications for Atrial Fibrillation

RV pacing (RVP), even with preserved atrioventricular (AV) synchrony, may lead to left atrial (LA) enlargement and atrial fibrillation. However, inciting events are unknown. We hypothesized that RVP acutely impairs LA function by mechanisms affecting atrial contraction and/or ventricular diastole. LA function in ICD patients (n = 31, LVEF ≤ 40%) and controls (n = 14, LVEF > 50%) was contrasted between intrinsic conduction versus RVP during asynchronous (ICD, n = 17, control, n = 7), and synchronous (ICD, n = 14, control, n = 14) pacing at long (LAVd, 107 ±16 ms) and short (SAVd, 31 ± 5 ms) AV delays. LA maximal volume (LA(Max)), minimal volume (LA(Min)), and emptying fraction {LA(EmF) = (LA(Max) -LA(Min))/LA(Max)} were measured echocardiographically. Six-segment mean mitral annular tissue doppler E' (global E') assessed diastolic recoil during baseline and LAVd. In the ICD group, LA(Min) increased by 42% (P < 0.0009) during VVI, by 31% (P = 0.0002) during SAVd, and by 17% (P < 0.0007) during LAVd. LA(EmF) decreased by 44% (P < 0.0008), 27% (P < 0.0001), and by 15% (P = 0.003) during VVI, SAVd, and LAVd respectively. LA(Max) was unaltered. Global E' was reduced by 12%. In control, LA(Min) increased and LA(EmF) decreased significantly during VVI (82 and 58%) and SAVd (46 and 41%), but not during LAVd. In patients with LV dysfunction, RVP acutely impaired LA emptying, and increased minimal volume, most prominently when atrial contraction was impeded (VVI, DDD-SAVd) but also when completed (DDD-LAVd), indicating impaired diastolic recoil as an important mechanism. When LV function was normal, similar changes were present when atrial filling is impeded (VVI, SAVd), but not when completed (LAVd).

Neural Mechanism of Atrial Fibrillation: Insight from Global High Density Frequency Mapping

It has been demonstrated that intrinsic cardiac autonomic activation of ganglionated plexi (GPs) exhibits a frequency gradient from the center to the periphery with limited mapping. We aimed to use a global mapping tool (Ensite Array) to identify the frequency distribution and clarify the interaction between the extrinsic/intrinsic autonomic systems. A mid sternal thoractomy was performed in anesthetized dogs. High frequency stimulation (20 Hz, 0.1 ms duration) was applied to locate the GPs and achieve vagosympathetic stimulation (VNS). There were 4 major GPs, which were located near the 4 pulmonary vein (PV) ostia, and a third fat pad (SVC-Ao) GP that was located near the superior vena cava (SVC)-right atrial (RA) junction. Without VNS (n = 12), the left atrial (LA) mean (8.20 ± 0.11 vs 7.95 ± 0.30 Hz, P = 0.04) and max (9.86 ± 0.28 vs 9.43 ± 0.29 Hz, P = 0.03) DFs were higher during the PV ostial GP stimulation than the SVC-Ao GP stimulation. The LA max DFs were located not only at the primary GPs but also the nearby secondary PV ostial GPs. The RA mean DF (8.36 ± 0.05 vs 7.99 ± 0.19 Hz, P = 0.04) was higher during SVC-Ao GP stimulation than PV ostial GP stimulation. The max DF was located inside the SVC during SVC-Ao GP stimulation and at the RA septum during PV ostial GP stimulation. With VNS (n = 12), the LA mean and max DFs between the PV ostial and SVC-Ao GP stimulation were similar. The DF distribution shifted to non-GP LA sites during both the PV ostial and SVC-Ao GP stimulation. The findings indicate that the AF was caused by an interaction between the PV ostial GPs during intrinsic autonomic stimulation, whereas the non-GP LA sites were responsible for the AF induced by an extrinsic neural input.

Evaluation of right atrial size and function after radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation using real-time three-dimensional echocardiography

Objective To assess the changes of right atrial size and mechanical function after radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation using real-time threedimensional echocardiography(RT-3DE), and to study the correlation between the changes of left atrial(LA)and right atrial(RA) volume and function. Methods Thirty-five patients with paroxysmal atrial fibrillation were undergone radiofrequency catheter ablation (RFCA) successfully. Transthoracic echocardiography (TTE),tissue Doppler imaging(TDI) and RT-3DE were performed before, 1 month and 3 months after procedure respectively. Late systolic volume and area of RA and LA,ejection fraction(EF) of RA and LA,late diastolic peak velocity of mitral valve inflow, tricuspid valve inflow and late diastolic peak velocity of mitral annulus and tricuspid annulus were recorded. Results The 3DE images of all patients were satisfied.LA max area and 3DE LA max volume were significantly reduced at 1 months and 3 months after procedure compared with basic stage [ ( 18.8 ± 6.3) cm2 vs (21.5 ± 6.2) cm2 , (38.8 ± 17.0) ml vs (46.1 ± 20.0) ml,P ＜ 0.05]. 3DE LA EF also declined markedly at 1 month after RFCA, and restored at 3 months later compared with baseline [(41.1 ± 13.7) % vs (51.7 ± 15.9) %, (41.1 ± 13.7) % vs (45.6 ± 18.3) %, P ＜0.05]. The size and mechanical function of the right atrial after procedure were no obvious changes. There were no evidently correlation between the changes of LA and RA volume and function. Conclusions RT3DE can provide a precise method to quantify the value of atrial volume and function. The LA size and volume are significantly reduced after RFCA in patients with paroxysmal atrial fibrillation, however, the RA size and function are no obvious changes. Key words: Echocardiography,real-time three-dimensional; Atrial fibrillation; Catheter ablation; Atrial function