Clinical Investigation
Congenital Heart Disease
Left Atrial Systolic Force in Children: Reference Values for Normal Children and Changes in Cardiovascular Disease With Left Ventricular Volume Overload or Pressure Overload

https://doi.org/10.1016/j.echo.2009.05.015Get rights and content

Background

Recent studies in adults have indicated that left atrial (LA) systolic force (LASF) provides useful information about LA pump function and can be used to predict cardiovascular events. However, normal values of LASF in children are not available, and little is known about atrial function in pediatric patients with heart disease. The objectives of the present study were to provide reference values for LASF in children and to determine LA pump performance in pediatric patients with heart disease using LASF.

Methods

LASF was measured using combined two-dimensional imaging and Doppler echocardiography in 185 healthy children and 71 pediatric patients with ventricular septal defects (VSDs; as a representative heart disease with chronic left ventricular [LV] volume overload; n = 48) or coarctation of the aorta (COA; as a representative heart disease with chronic LV pressure overload; n = 23).

Results

LASF in children significantly increased with advancing age (P < .005). The major determinants of this change were body surface area, stroke volume, and heart rate, with a linear model fit (r2) of 0.72. In patients with VSD and those with COA, LASF was significantly elevated in proportion to the degree of LV volume or pressure load, suggesting adaptive mechanisms of LA pump function to facilitate LV filling in chronically overloaded hearts. LASF was normalized after anatomic correction of VSDs but remained elevated even after the relief of COA, indicating persistent overwork of the left atrium.

Conclusions

The present study provides reference data for the evaluation of atrial function in pediatric patients with cardiac disease. In addition, altered LASF in patients with VSDs with even small left-to-right shunts and in those with COA even after anatomic correction may have pathologic implications that could lead to a novel therapeutic target.

Section snippets

Patients

Of 230 prospectively studied subjects aged <18 years who were referred to our outpatient clinic for the evaluation of suspected electrocardiographic abnormalities, heart murmurs, or chest pain, 185 who were eventually confirmed to be normal and whose echocardiographic data were acceptable for analysis were enrolled in the present study to determine the reference values of LASF in children. Furthermore, changes in LASF associated with cardiovascular disease were studied in 71 consecutive

Age-Related Reference Values for LASF

Table 1 summarizes the demographic, hemodynamic, and echocardiographic characteristics of ventricular function and geometry of each group. The ages of normal subjects ranged from 10 days to 18 years. Figure 1 demonstrates the age-associated changes in LASF in normal children. LASF significantly increased with advancing age, with the regression equation given by 0.265 Ă— age (y) + 2.83 (r = 0.71, P < .001). There was no gender difference in this relationship (P = .86 for offset, P = .88 for

Discussion

The principal function of the left atrium is to modulate LV filling and thereby to modulate cardiovascular performance. This is accomplished through its well-defined actions as a booster pump during atrial systole and as a distensible reservoir and passive conduit for pulmonary venous flow during ventricular systole and early ventricular diastole, respectively.15 This study presents for the first time a reference value for developmental changes in LA booster pump function during childhood as

Limitations

As defined in the present study and previous reports, LASF represents an estimation of the force exerted by the contracting left atrium to accelerate blood into the left ventricle and should not be misinterpreted as an assessment of total atrial force. There are no valves between the incoming pulmonary veins and the left atrium, and atrial contraction leads a variable degree of transient pulmonary venous backflow. In patients with VSDs, the markedly increased pulmonary flow and thus pulmonary

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    This study was supported by national grant 8025127 from the Japan Society for the Promotion of Science to Dr Senzaki and medical research grants to Dr Senzaki from Nipro Corporation, the Kawano Memorial Foundation (H.S.), and Tenshindo Medical Institution (H.S.).

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