Normality of upper and lower peripheral pulse transit time of normotensive and hypertensive children.
OBJECTIVE
The ankle-brachial index (ABI) is known to be indicative of sub-clinical peripheral arterial diseases that are correlated with cardiovascular disease risk factors like atherosclerosis or ischemic extremity. Due to its occluding measurement nature, this may not be appealing to less cooperative patients when multiple prolonged screening is required. A simple and non-intrusive approach termed pulse transit time ratio (PTTR) has recently shown to be potential surrogate marker for the prolonged ABI measurement. Other studies have also suggested that subjects with hypertension have stiffer arterial wall and thereby can confound transit time related parameters. Thus, it becomes important to understand the PTTR normality and difference of hypertensive children when compared to those measured from normotensive children.


METHODS
About 55 normotensive (39 male; aged 8.4 +/- 2.3 yr) and 4 hypertensive (4 male; aged 5-10 yr) Caucasian children were recruited from the same geographical location. A customized device was used to compute pulse transit time related measurements. Since the PTTR approach produced a delta value that was similar to that of ABI, possible inter-subject physiologic differences had limited confounding effects on the derived PTTR parameter.


RESULTS
The obtained transit time measurements from the hypertensive children had lower pulse transit time value when compared to their normotensive counterparts. However, the statistical analysis indicated that they had insignificant PTTR difference (p > 0.01) from those seen in the normotensive children.


CONCLUSIONS
The findings herein suggest that stiffer arterial wall may have confounding effects on the derived transit time related measurements but it is limited on the PTTR parameter. Similar to the ABI approach, PTTR may be only confounded by abnormal local changes in either of the measured peripheral arterial wall. Hence, the PTTR technique shows promise to be an ABI marker from this perspective.
Foo
Jong Yong Abdiel
JY
Biomedical Engineering Research Centre, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Xfrontiers Block, Singapore, Singapore. jong@ntu.edu.sg
D000842:Ankle / Q000098:blood supply; D001916:Brachial Artery / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D003935:Diagnostic Techniques, Cardiovascular / Q000706:statistics & numerical data; D004562:Electrocardiography; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D016491:Peripheral Vascular Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D017156:Photoplethysmography / Q000706:statistics & numerical data; D011674:Pulse / Q000379:methods* / Q000706:statistics & numerical data; D012016:Reference Values