Original Contribution
Characterization of the Left Atrial Vortex Flow by Two-Dimensional Transesophageal Contrast Echocardiography Using Particle Image Velocimetry

https://doi.org/10.1016/j.ultrasmedbio.2012.08.013Get rights and content

Abstract

This article is the first clinical investigation of the quantitative left atrial (LA) vortex flow by two-dimensional (2-D) transesophageal contrast echocardiography (2-D-TECE) using vector particle image velocimetry (PIV). The aims of this study were to assess the feasibility of LA vortex flow analysis and to characterize and quantify the LA vortex flow in controls and in patients with atrial fibrillation (AF). Thirty-five controls and 30 patients with AF underwent transesophageal contrast echocardiography. The velocity vector was estimated by particle image velocimetry. The morphology and pulsatility of the LA vortex flow were compared between the control and AF groups. In all patients, quantitative LA vortex flow analysis was feasible. In the control group, multiple, pulsatile, compact and elliptical-shaped vortices were seen in the periphery of the LA. These vortices were persistently maintained and vectors were directed toward the atrioventricular inflow. In the AF group, a large, merged, lower pulsatile and round-shaped vortex was observed in the center of the LA. In comparisons of vortex parameters, the relative strength was significantly lower in the AF group (1.624 ± 0.501 vs. 2.105 ± 0.226, p < 0.001). It is feasible to characterize and quantify the LA vortex flow by transesophageal contrast echocardiography in patients with AF, which offers a new method to obtain additional information on LA hemodynamics. The approach has the potential for early detection of the LA dysfunction and in decisions regarding treatment strategy and guiding anticoagulation treatment in patients with AF.

Introduction

It is known that atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. The incidence and prevalence of AF increase with age and coexisting cardiopulmonary diseases (Feinberg et al. 1995; Heeringa et al. 2006). The hemodynamic impairment and thromboembolic events associated with AF result in significant morbidity, mortality and socioeconomic cost (Fuster et al. 2006). In particular, thromboembolic complications, including ischemic stroke, are the most devastating potential consequences of AF; therefore, early and accurate assessment of the left atrial (LA) dysfunction is crucial in managing patients with AF.

Although conventional Doppler echocardiography is the most widely used and simple diagnostic tool to evaluate the LA function (Nishimura et al. 1985) and to identify high risk for thromboembolic events (Pop et al. 1994) in daily practice, it has several limitations in the assessment of early hemodynamic changes of the LA and prediction of thromboembolic risk in patients with AF. Thus, characterization and quantification of the LA flow pattern has the potential benefit to estimate LA function and to predict thromboembolic events in patients with AF.

Recently, it has been demonstrated that characterization and quantification of the left ventricular (LV) vortex flow using contrast echocardiography (CE) is feasible (Hong et al. 2008). However, there have been no data on the assessment of LA vortex flow using two-dimensional (2-D) transesophageal contrast echocardiography (TECE). The aims of this study were to assess the feasibility of LA vortex flow analysis and to characterize and quantify LA vortex flow using 2-D-TECE in controls and patients with AF.

Section snippets

Study population

Sixty five subjects undergoing transesophageal echocardiography (TEE) between October 2008 and March 2010 at Yeungnam University Hospital were prospectively enrolled in this study. The patients composed 35 normal controls (age 57 ± 12 years) and 30 patients with AF (age 59 ± 12 years). Patients with persistent AF according to American College of Cardiology/American Heart Association/European Society of Cardiology guidelines (Fuster et al. 2006) who presented with complaints of palpitation,

Data analyses

The clinical characteristics of each group are presented in Table 1. The average age was 57 ± 12 years in controls and 59 ± 12 years in patients with AF. There were 22 (62.9%) and 21 (70.0%) men in the control and AF groups, respectively, 15 hypertensives (42.9%) and 10 diabetics (28.6%) in the control group, and 14 hypertensives (46.7%) and five diabetics (16.7%) in the AF group. There were no significant differences for all variables between the control and AF groups.

Comparison of 2-D-transthoracic echocardiographic parameters in two groups

The 2-D-TTE results for

Discussion

This study is the first clinical comparison study of controls and patients with AF to characterize LA vortex flow using 2-D-TECE. By this approach, characterization and quantification of the LA vortex flow was feasible and distinctions in LA vortex flow pattern between controls and patients with AF could be identified. We have attempted to understand and quantify characteristics of the LA vortex flow and have identified the possibility of application to the clinical field.

In the clinical

Conclusion

It is feasible to characterize and quantify the LA vortex flow by 2-D-TECE in controls and patients with AF, which offers a new method to obtain additional information on LA hemodynamics and has the potential for early detection of the LA dysfunction and application for decision-making regarding treatment strategy and in guiding anticoagulation treatment in patients with AF. Further confirmatory studies to assess clinical implications are necessary.

Acknowledgments

This research was supported by a grant of Yeungnam University Medical Center (2009). Dr. Geu-Ru Hong received research support from Siemens Medical Solution.

References (26)

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