Vascular health evaluation
Endothelial function by peripheral arterial tonometry (PAT)
Non-invasive peripheral endothelial function will be assessed by reactive hyperemia index (RHI) using Endo PAT 2000 Machine (Itamar Medical Ltd, Caesarea, Israel). Endothelial function test will be administrated by a trained staff in a separate room and was performed in the morning or early afternoon (starting time between 7:30 AM and 11:00 AM). The Endo-PAT data were analyzed with the proprietary software package, without any input from the examiner and has been developed to measure observer independent pulsatile arterial volume changes by finger plethysmography. The temperature of the testing environment is 22-25 ℃, dim the lights and keep quiet. The required equipment includes a comfortable examination bed, a computer, Endo-PAT equipment, hand support, and a blood flow occlusion meter. The test takes a total of 16 minutes, including baseline 6 minutes, interruption of 5 minutes, and release of 5 minutes. The subject takes a supine position, relax, and his arms can be placed flat on both sides of the body. Subjects avoid smoking, eating food, coffee or other drinks (drinking water is allowed) at least 3 hours before the test. The biosensor is worn on the index finger (second finger) and bind the cuff of the non-habitual hand to block the blood flow. Tentatively, the RHI<1.67 is regarded as endothelial dysfunction. At present, there is no study on the normal reference value of RHI, and our study will also preliminarily establish the normal range of RHI in Chinese population.
Arterial stiffness by brachial-ankle artery pulse wave velocity (ba-PWV) examination
Ba-PWV is examined by automatic detection equipment for arterial function (MB-3000, China). Keep the room temperature at about 22-25 ℃ in the examination room. The examinee should rest for at least 5 minutes before the measurement; rest for about 20 minutes after any exercise before starting the measurement. Install cuff on both arms and ankles, left upper arm (yellow), right upper arm (red), left ankle (green), right ankle (black). The air duct orifice of the upper arm cuff is placed on the same axis as the brachial artery of the upper arm, and the lower edge of the cuff is 2 to 3 cm, from the elbow fossa so that the upper and lower edges can only enter one finger. Extend the air hose on the ankle cuff upward along the medial side of the ankle. The lower edge of the lower limb cuff is 1 to 2 cm horizontally away from the medial malleolus. Place electrocardiogram (ECG) electrodes on the left and right wrist. Place the heart sound sensor at the second rib level of the right edge of the sternum or the third rib level in the middle of the sternum or the fourth rib level of the left edge of the sternum. Enter the examinee’s information, click the start button when each waveform is stable, and the machine will automatically analyze the results. Age and sex adjusted ba-PWV values are used to define arteriosclerosis.
Cardio-ankle vascular index (CAVI) evaluation
CAVI is examined by vascular equipment (VS-1500, Fukuda, Japan). Cuff, heart sound sensor and ECG electrode are placed in the same way as MB. After observing that the waveform on the screen is stable, press the start key to start the measurement. After hearing the deflation sound, there should be six (+) signs on the screen, two in each row. Some of the examined blood vessels have severe hardening or stenosis, and there should be at least three (+) signs, one in each row. Confirm that the CAVI self-test result is ”+” or ”+”. If it is ”-” or ”-”, please reconfirm that the ECG electrodes, cuffs and heart sound sensors are connected correctly. CAVI >9 on either side will be defined as arteriosclerosis.