Related Experiment Videos
The pulse wave arrival time (QKd interval) in normal children
Insights
The QKd interval, measuring pulse wave arrival time, was standardized for children using height correction. This allows for clinical studies in children and reveals progressive arterial stiffening with age.
Area of Science:
- Pediatric Cardiology
- Biomedical Engineering
- Vascular Physiology
Background:
- The QKd interval measures pulse wave arrival time, valuable for assessing cardiovascular health in adults.
- Standardization of QKd measurements in children is crucial for pediatric clinical studies.
Purpose of the Study:
- To standardize the QKd interval measurement in a pediatric population.
- To establish normal ranges for QKd in children aged 7 months to 18 years.
- To investigate the relationship between pulse wave velocity (PWV) and age in children.
Main Methods:
- Measurements of the QKd interval were obtained from 63 healthy children.
- A regression equation was developed to correct QKd for height (QKd = 56.6 + 0.797H).
- Pulse wave velocity (PWV) was calculated and correlated with age.
Main Results:
- A height-corrected QKd equation was established: QKd = 56.6 + 0.797H (H in cm).
- Pulse rate correction was found unnecessary for resting subjects.
- PWV increases with age (PWV = 2.44 + 0.203 A) with r = 0.823, indicating decreasing arterial elasticity.
Conclusions:
- The derived QKd equation enables standardized clinical assessments in children.
- The findings suggest a progressive loss of arterial functional elasticity throughout childhood.
- This research provides a basis for utilizing QKd interval in pediatric cardiovascular research.
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.