Morphological analysis of peripheral arterial signals in Takayasu's arteritis

Takayasu's arteritis disease (TA) remains a rarely studied chronic inflammatory disease. Our objective is to analyze peripheral pulse using photoplethysmography (PPG) as a new assessment method for diagnosing TA. So far no literature reports detailed morphological analysis of TA PPG signals. PPG signals of twenty normal and twenty TA patients at five different regions such as left and right thumbs, left and right toes and neck have been acquired simultaneously. Morphological parameters of peripheral signals such as peak-to-peak time, the crest time (CT), reflection index (RI), maximum systolic slope (MSS), maximum diastolic slope, pulse height, area under pulse and pulse transit time are obtained from PPG and electro cardiogram of normal and TA patients. Surprisingly RI is different in all the five locations of TA patients, whereas it is same for normal in all five locations. Mean MSS are significantly lesser than normal subjects. Mean CT of normal subjects is always lesser than normal subject. Morphological parameters based classification method has sensitivity of 80-100 and specificity of 86-100 in all limbs/all parameters. Bilateral dissimilarity in morphological parameters of multi site peripheral signals in the TA patients can be used to diagnose TA patients and find the pathological site. Less population is studied which reflects the rarity of the TA disease.