Centile Curves for Velocity-Time Integral Times Heart Rate as a Function of Ventricular Length: The Use of Minute Distance Is Advantageous to Enhance Clinical Reliability in Children

BACKGROUND: The generation of velocity-time integrals (VTIs) from Doppler signals is an essential component of standard echocardiographic investigations. The most effective algorithm to compensate for growth in children has, however, not yet been identified. This study was initiated to establish pediatric reference values for VTI and to enhance the interpretability of those values, considering technical and physiological factors. METHODS: The echocardiographic data sets of healthy children and adolescents (N = 349; age range, 0-20 years) were recorded in a prospective approach and subsequently analyzed. In a pilot study, aortic and pulmonary VTIs were set in relation to the physiologic parameters of heart size as possible influencing parameters in a subgroup of children with comparable physical characteristics. The ratio with the smallest SD was taken as the base to generate centile curves using the LMS method. The clinical utility of the model was tested by examining patients (n = 80) with shunt lesions such as patent ductus arteriosus and atrial septal defect. RESULTS: Feasibility was 94.6% for aortic VTI and 92.8% for pulmonary VTI. The pilot study identified ventricular length and heart rate as suitable parameters with the lowest relative SDs and high correlations with VTI. Gender differences were not relevant for children <7 years of age, and with increasing age, SD increased because of higher stroke volume variations. The detection of increased aortic VTI was possible with sensitivity of 73% for patients with patent ductus arteriosus with moderate or large hemodynamically significant ductus arteriosus. Patients with atrial septal defects with enlarged right ventricles could be identified as having increased pulmonary VTI with sensitivity of 84%. CONCLUSIONS: These new reference values for VTI times heart rate as a function of ventricular length may be of specific clinical value to improve the assessment of cardiac function, therapeutic decision making, and follow-up in pediatric patients with heart disease.