Cardio-Ankle Vascular Index Ultrasound Measurement And Clinical Evaluation

BackgroundBackground Arteriosclerosis is a major contributor to cardiovascular disease, accounting for a high percentage of mortality and morbidity. Recently, a new atherosclerotic index, the cardio-ankle vascular index (CAVI), has been developed by measuring Pulse Wave Velocity (PWV) and Blood Pressure (BP). CAVI is usually measured from an ECG, phonocardiogram (PCG), brachial artery waveform, and ankle artery waveform and calculated using a specific algorithm. Here we explore a new way to acquire CAVI by applying ultrasound technology. To detect the Brachial-ankle PWV (baPWV), we needed to obtain the brachial and ankle pulse waves by applying air pressure using the volume plethysmographic method. And electrocardiogram and heart sound were monitored. The time taken for the pulse wave to propagate from the aortic valve to the ankle was difficult to obtain. Because the starting time of the blood stream from the aortic valve is difficult to identify from the valve's opening sound. Here we try to detect the aortic and ankle flow directly by applying ultrasonic probe to obtain CAVI, and explore the CAVI ultrasound measurement and discuss its clinical evaluation.Objective1. The purpose of this part of study was to evaluate the validity and reproducibility of CAVI ultrasound measurement.2. To observe if there has a significant relationship between CAVI ultrasound measurement and volume plethysmographic method, then compare those with other parameters such as SBP, IMT,β.3. To evaluate the sensibility and specialty of CAVI ultrasound measurement, we explore them in the people with thickening IMT and compare it with other methods such as baPWV andβ.Materials and Methods1. We obtain CAVIm and CAVId by applying M-mode and Color Doppler Flow Imaging (CDFI) respectively. Check the reproducibility of CAVI measured by ultrasound in 20 subjects which choose randomly from 102 subjects. 2. Use the professional equipment (BP-203RPEⅡ,VP-1000,made in Japan) to gain CAVI(CAVIp) ,then measure CAVI by M-mode and Color Doppler Flow Imaging(CDFI) to obtain CAVIm and CAVId. All subjects underwent carotid ultrasound (CU) and measurement of intima-media thickness (IMT) andβ.3. A total of 80 participants who underwent CAVI were enrolled in the current study. All subjects underwent carotid ultrasound (CU) and measurement of intima-media thickness (IMT) andβ. They were divided into 2 groups according to the intima-media thickness (IMT), normal (maximum IMT≤0.8mm), (IMT≥1.1mm) groups . Applying M-mode to obtain CAVI,and use the professional equipment (BP-203RPEⅡ, VP-1000, made in Japan) to get baPWV and Compare the specialty and the sensitivity of those artery elasticity parameters between groups.Results1.There were significant relationships of CAVIm between inter-observer and intra- observer(r=0.933,r=0.939,P<0.01), There were also significant relationships of CAVId between inter-observer and intra-observer(r=0.962 , r=0.975 respectively, P<0.01).2.There were significant correlations between CAVIm and CAVIp,CAVId and CAVIp. There were significant relationships between CAVIm and IMT,β(r=0.824, P <0.01,r=0.812,P <0.01, respective), and between CAVId and IMT, (r=0.815,P<0.01;r=0.813,P<0.01;respective)3. CAVI has a significantly sensitivity in IMT(0.9mm,1.1mm)group compared with baPWV,β(p<0.01), and was slightly lower of specialty in IMT(0.9mm,1.1mm)group compared with the baPWV,β(p<0.05).ConclusionsThe present study confirms the validity and reproducibility of noninvasive CAVI ultrasound measurement, and suggests that CAVI ultrasound measurement is an acceptable marker of vascular damages comparable to the CAVI obtained by volume plethysmographic method. This study has shown that CAVI, measured by ultrasound, has a significantly sensitivity and strongly associated with the presence of carotid atherosclerosis and has a potential application for screening vascular damages in a large population.