Online Quantification of Cardiovascular Function in Children.

Echocardiography is the most valuable diagnostic tool in evaluating congenital anatomic pathology. Improvements in transducer resolution and development of color Doppler echocardiography have resulted in the ability to delineate cardiac anatomy in detail. Online quantification of cardiovascular function represents a similar advance in terms of evaluating physiology. Performing an online quantification examination requires attention to technical factors such as avoiding chamber foreshortening, optimizing endocardial tracking, ensuring patient cooperation, and accounting for the effects of respiration. A typical examination consists of performing acoustic quantification on the left ventricle in both short-axis and apical four-chamber views and on the left atrium from the apical four-chamber view. From these views, ventricular systolic and diastolic function, as well as atrial systolic function, can be assessed. As in adult patients, acoustic quantification indices in children correlate well with similar indices measured off line. Acoustic quantification data in children show that, unlike adults, the left ventricular filling is almost exclusively dependent on passive filling, with minimal atrial contribution. Acoustic quantification indices have also been useful in monitoring left ventricular function in intensive care and emergency department settings to evaluate the acute effects of a clinical manipulation. Acoustic quantification can also be used to assess the function of ventricles of unusual geometry such as in hypoplastic left and right heart, double-inlet single ventricle, and unbalanced atrial ventricular septal defect. In these types of ventricles, systolic and diastolic systemic ventricular function has been shown to be markedly altered compared with a normal left ventricle. Acoustic quantification can also be used to assess diastolic function in a variety of pediatric diseases, such as transplant rejection and insulin-dependent diabetes mellitus. In summary, online quantification of cardiovascular function represents a significant advance in the ability to understand cardiovascular physiology in children.