Wideband External Pulse Recorded During Cuff Blood Pressure Measurement: A New Technique for Cardiovascular Assessment.

INTRODUCTION: The wideband external pulse (WEP) recorded during blood pressure measurement reveals three components (K1, K2, K3). K1 is recorded with cuff pressure (CP) above systolic (SP). AIM: To assess whether the K1 pattern contains information about the functional and structural properties of the cardiovascular system. METHODS: WEP analysis, echocardiography, carotid artery (CA) ultrasonography and applanation tonometry were conducted on 178 hypertensives. K1R, a feature of K1, was defined to provide a measure between the arterial incident and backward reflective waves. RESULTS: K1R was strongly correlated to vascular functional and structural parameters compatible with vascular effects of aging and hypertension. ANOVA analysis (K1R < 0 vs K1R > 0) showed that K1R < 0 participants: (1) were older, shorter, weighed less, had a smaller body surface area; (2) had higher SP, pulse (PP) and mean (MP) pressure, lower heart rate (HR), greater total peripheral resistance (TPR), lower cardiac output (CO), and a stiffer arterial system; (3) had a greater left ventricular (LV) relative wall thickness (LVRWT), carotid artery (CA) relative wall thickness (CARWT), CA far-wall intima-media thickness at end diastole (CIMTd) and CA cross-sectional area (CSA) (all p < 0.001). Regressions revealed that age, TPR, SP, gender, and HR predicted K1R (R2 = 0.64) and that PP and K1R predicted CARWT (R2 = 0.14). Logistic regression revealed that age, TPR, SP and aortic diameter differentiated K1R < 0 from K1R > 0 (Nagelkerke R2 = 0.77). CONCLUSIONS: K1R is related to vascular functional properties, with suggestive evidence that K1R is also related to vascular structural properties and perhaps subsequent cardiovascular risk.

Digital signal processing of the wideband external pulse recorded during cuff deflation: a new way to measure blood pressure.

Aa new method of measuring blood pressure (BP) is presented. This technique involves automatic analysis of the wideband external pulse (WEP) recorded by a pressure sensor positioned over the brachial artery during standard BP cuff deflation. Three distinct components of this "K" or "WEP" signal can be defined: K1, K2, and K3 [1]. Each component has a different shape and "appearance/disappearance property. K1 is a low frequency inaudible signal present with cuff pressure above systolic. The K2 signal appears at SP and disappears at Dp (K2-algorithm) and can be used to measure BP. Using this property, the "K2-algorithm" has been shown to be more accurate than the auscultatory technique [1]. To implement an automatic measurement using the K2-algorithm, signal processing techniques are applied to K signals.