Left atrial volume assessed by transthoracic three dimensional echocardiography and magnetic resonance imaging: dynamic changes during the heart cycle in children

Abstract

Objective: To assess the dynamic changes in left atrial volume by transthoracic three dimensional echocardiography and compare the results with those obtained by magnetic resonance imaging (MRI).

Design and patients: 30 healthy children (15 boys and 15 girls, aged 8 to 13 years) underwent examination by three dimensional echocardiography and MRI.

Methods: Three dimensional echocardiography of the left atrium was performed using rotational acquisition of planes at 18 degrees intervals from the parasternal window with ECG gating and without respiratory gating. Volume estimation by MRI was performed with a slice thickness of 4-8 mm and ECG triggering during breath holding in deep inspiration. A left atrial time-volume curve was reconstructed in each child.

Results: Left atrial maximum and minimum volumes averaged 24.0 ml/m(2) and 7. 6 ml/m(2) by three dimensional echocardiography, and 22.1 ml/m(2) and 11.9 ml/m(2) by MRI. The greater left atrial minimum volume in the latter was at least in part a result of breath holding. Dynamic changes in left atrial volume during the heart cycle were detectable by both methods. The higher temporal resolution of three dimensional echocardiography allowed a more precise evaluation of different phases.

Conclusions: Three dimensional echocardiography and MRI were both useful methods for studying the physiological volume changes in the left atrium in children. These methods may be used for further study of the systolic and diastolic function of the heart.

Figure 1

Left atrial time-volume curve in a 9 year old boy. (a) Minimum volume. (b) Maximum volume. (c) Mid-diastolic volume (15% from the end of the heart cycle). c-a, atrial stroke volume; b-a, cyclic volume change.

Figure 2

Reconstruction of left atrial maximum and minimum volumes produced by the three dimensional software when 10 scanning planes were used.

Figure 3

Bland-Altman agreement plots for left atrial maximum volume estimation by three dimensional echocardiography (3DE) in comparison with MRI. Dotted line represents the mean difference (bias). Dashed line represents ±2 SD from the mean between the two techniques.

Figure 4

Bland-Altman agreement plots for left atrial minimum volume estimation by three dimensional echocardiography (3DE) in comparison with MRI. Dotted line represents the mean difference (bias). Dashed line represent ±2 SD from the mean between the two techniques.

Figure 5

Averaged left atrial time-volume curves during the heart cycle in 30 children. (A) Assessment with three dimensional echocardiography. (B) Assessment with MRI: a, heart rate at the beginning of MRI scanning; b, heart rate at the end of MRI scanning.