The pulse wave arrival time (QKd interval) in normal children

Abstract

The interval between the onset of QRS of the electrocardiogram and the arrival of the pulse wave at the brachial artery, as detected by the appearance of Korotkoff sounds at diastolic pressure (QKd), provides a measure of a pulse wave arrival time, i.e., the sum of the pre-ejection period and a pulse transmission time. This measurement has proven useful in the evaluation of cardiovascular disease, thyroid and catecholamine status, and several other conditions in adults. In order to standardize this measurement in children, measurements were obtained on 63 normal children ranging in age from 7 months to 18 years. Because of the dependence of pulse transmission time on the distance of propagation, the QKd interval (in msec) is related to height (H in cm) by the equation: QKd = 56.6 + 0.797H. By use of this equation one can obtain a "height corrected QKd." Correction for pulse rate is not necessary for resting subjects. These normal ranges permit use of the QKd interval for clinical studies in children. These studies also permit measurement of the mean pulse wave velocity for a group of individuals. PWV (m/sec) increases with age according to the equation: PWV = 2.44 + 0.203 A, (A in years) with a correlation coefficient of r = 0.823. This implies progressive loss of functional elasticity of the major arteries throughout childhood.