Atrioventricular Coupling in Infants and Children Assessed by Three-Dimensional Echocardiography.

BACKGROUND

Parameters of the interaction of the left atrium and left ventricle, atrioventricular (AV) coupling, are used in the diagnosis and follow-up of diastolic dysfunction in adults. Pediatric parameters of AV coupling have not been evaluated so far. The aim of this multicenter study was to investigate parameters of AV coupling in a large cohort of healthy infants and children using noninvasive real-time three-dimensional echocardiography. The authors hypothesized that the contribution of the different left atrial (LA) volumes to left ventricular (LV) stroke volume differs over a range of different heart rates.

METHODS

Three-dimensional echocardiographic data sets from 332 subjects (ages 0 days to 18.5 years) were analyzed prospectively. Volume-time curves of the left atrium and left ventricle were generated. Conduit volume was calculated and percentiles were established by the lambda-mu-sigma method of Cole and Green. Contributions of active, passive, and conduit volume to LV filling were measured and related to heart rate by linear regression. LV and LA peak filling rates (PFR) and peak emptying rates (PER) and time to PFR and PER normalized to the R-R interval (PFR[%] and PER[%]) were measured and correlated to each other.

RESULTS

Conduit volume increased with body surface area. The contribution of LA active emptying to LV filling tended to increase with decreasing heart rate, while the contribution of passive emptying decreased. Conduit volume contributed most to LV filling (median, 57.58 %; interquartile range, 12.85%) with a tendency to increase with decreasing heart rate. Close diastolic AV coupling was demonstrated by virtually identical LV PFR(%) and LA PER(%) during diastole. LV PER(%) occurred earlier than LA PFR(%), showing less coupling during systole. LV PFR(%) and LA PER(%) were strongly correlated to heart rate (r = 0.76 and r = 0.73, respectively). Lower heart rate resulted in a prolongation of diastole after LV PFR.

CONCLUSIONS

Assessment of conduit volume and AV coupling by three-dimensional echocardiography is feasible in infants and children. The references of this study can serve as a basis to further investigate the role of parameters of AV coupling in pediatric patients with heart diseases concerning diastolic and LA function.