Browsing by Author "Witbooi, Lee-Roy Cecil"

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    Accurate estimation of large vessel length in growing children and adolescents for the purpose of pulse wave velocity calculation.
    (Stellenbosch : Stellenbosch University, 2018-12) Witbooi, Lee-Roy Cecil; Innes, Steve; Page, Ben; Pitcher, Richard; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Anatomy and Histology.
    Background Cardiovascular disease is a major cause of death in adults worldwide. Early detection allows for early intervention to prevent vascular events such as strokes, heart attacks, etc. Although these vascular events typically occur in late adulthood, the underlying atherosclerosis often begins during childhood. Early subclinical atherosclerosis can be detected by measuring the elasticity of the large arteries, particularly when performed serially over time. Normally, the elasticity of a healthy aorta helps to slow down the speed of the pressure wave created by contraction of the heart muscle. This is an important way of maintaining smooth laminar blood flow. Atherosclerosis causes the vessel wall to harden and lose elasticity. As the vessel wall hardens, the speed of the pressure wave increases. Pulse wave velocity (PWV) is a sophisticated method of detecting early elasticity changes, and is a preferred non-invasive technique to measure arterial wall stiffness. The velocity calculation requires accurate measurement of both distance travelled and time taken for the pulse wave to travel between two points. The distance used for pulse wave velocity calculation is an approximation of the intraluminal distance travelled by the pulse wave and is estimated by measuring the distance between various surface anatomy landmarks. The expert consensus document on arterial wall stiffness described carotid–femoral PWV as the “gold standard” measurement of arterial wall stiffness, yet there is no consensus on the arterial path length estimation method. A variety of arterial path length estimation methods exist, and this makes inter-study comparison of PWV very difficult. The purpose of the current study was to investigate the most accurate method of estimating the true distance travelled by the aorto-femoral pressure wave. We compared distances between a range of commonly used surface anatomy landmarks, and compared these to the true intraluminal distance measured on multi-planar reformations of archived computerized tomography imaging in children of varying ages. Our findings will allow standardization of PWV calculation in children and allow for inter-study comparisons. Methods Vessel lengths in children (aged 0-18 years) were measured with multi-planar reformation (MPR) imaging software. These measurements were then compared with the surface anatomy measurements also obtained using the MPR imaging software. The comparisons between vessel lengths and surface anatomy distances were performed in segments, since there were no whole body CT scans available on the Picture Archiving and Communication System (PACS) at the research site. Results The surface anatomy measurements from the suprasternal notch to the angle of the mandible (on the right) correlated well with the intraluminal vessel length from the origin of the brachiocephalic trunk to the external carotid at the angle of the mandible (r2=0.92; p<0.0001). The surface anatomy measurements from the suprasternal notch to the midpoint of the right inguinal crease, correlated well with the intraluminal vessel length from the origin of the brachiocephalic trunk to the right femoral artery at the right inguinal ligament (r2=0.98; p<0.0001). The surface anatomy measurements from the suprasternal notch to the xiphisternum, plus the surface distance between xiphisternum and the umbilicus, plus the surface distance between the umbilicus and the midpoint of the right inguinal crease, correlated well with the intraluminal vessel length from the origin of the brachiocephalic trunk to the right femoral artery at the right inguinal ligament (r2=0.97; p<0.0001). The surface anatomy measurement from the suprasternal notch to the xiphisternum, plus the surface distance between the xiphisternum and the midpoint of right inguinal crease, correlated well with the intraluminal vessel length from the origin of the brachiocephalic trunk to the right femoral artery at the right inguinal ligament (r2=0.97; p<0.0001). A regression equation is provided for each set of surface anatomy measurements, allowing further adjustment of measurements to more accurately represent the true intraluminal distance travelled by the pulse wave. Conclusions The surface anatomy distance between the suprasternal notch and the angle of the mandible, subtracted from the distance between the suprasternal notch and mid-inguinal crease, provides the closest approximation of true intraluminal distance travelled and would be the best method to standardize pulse wave velocity calculation in children and adolescents. However, surface anatomy estimations using the xiphisternum and umbilicus as landmarks produced very similar correlations.