RF-data Combined X-strain Technique In Evaluating The Arterial Stiffness And The Correlation Between Arterial Stiffness And Cardiac Diastolic Function

Background and PurposeThe decrease of the arterial elasticity is the major characteristics of hypertension and is of important clinical significance. In addition, hypertension also impairs several organs including brain, kidney and especially the heart. For example, the left ventricular dysfunction is one of the typical outcomes of decreased arterial stiffness. In recent years, the correlation study between arterial stiffness and cardiovascular events becomes a hot issue in the clinical research.The purposes of this study were: 1. to compare the new parameters from RF of arterial strain and strain rate with traditional parameters that reflect arterial stiffness between patients with hypertension and normal subjects; 2. To explore the mechanism of the new parameters for reflecting the arterial stiffness and the mechanical principles of the changes of the arterial function in hypertensive patients. 3. To investigate the correlation between the arterial stiffness and the cardiac function.Patients and Methods1 PatientsThirty-five patients admitted for hypertension in Tangdu Hospital were include as case group and seventy-seven normal persons matched with age were included as control group. Hypertension was diagnosed according to the guideline of the WHO-ISH in 1999 (systolic pressure≥140mmHg,diastolic pressure≥90mmHg). Patients with diabetes and coronary heart disease were excluded.2 Data collectionData collection was performed using color Doppler ultrasound diagnostic equipment based of radio frequency data of ESAOTE Company (blood vessel probe, LA523, 4-13MHz; heart probe, PA230, 1-4 MHz). The intima-media thickness (IMT) of Bilateral common carotid artery were measured by QIMT technique; Parameters of blood vessel stiffness such as distensibility coefficient(DC), arterial compliance (AC),β, pulse wave velocity(PWV) were determined by QRS technique; In the long axis view, endovascular longitudinal strain rate(EN-LSR), endovascular longitudinal strain(EN-LS), adventitial longitudinal strain(EP-LS), adventitial longitudinal strain rate(EP-LSR)were detected, while in the short axis view, endometrial circumferential strain rate(EN-CSR), endovascular circumferential strain(EN-CS), adventitial circumferential strain(EP-CS), adventitial circumferential strain rate(EP-CSR)were determined. In patients with hypertension, echocardiogram was performed and parameters of diastolic function of left heart including E/A, e/a, isovolumic relaxation time(IVRT), left ventricular mass(LVM), left ventricular mass index(LVMI) were measured. The correlation between parameters of the arterial stiffness and cardiac function were analyzed.3. Statistical analysisStatistical analysis was performed using the SPSS17.0. Descriptive statistics were used to summarize baseline demographic data. Continuous data are expressed as mean (±standard error). The difference between the two groups was performed by student t test. Correlation between the parameter was performed by pearson correlation analysis. A P-value of < 0.05 was considered statistically significant for all analyses.ResultsPatients with hypertension had higher PWV and lower AC, EN-CS, EP-CS and EP-CSR (P < 0.05) of the common carotid artery; no significant difference of the length wise strain was detected between the two groups. In patients with hypertension, PWV correlated negatively with AC, E/A, e/a and positively with IVRT,LVM,LVMI (P < 0.05); endovascular circumferential strain correlated negatively with PWV and positively with AC; IMT correlated negatively with E/A, e/a and positively with IVRT, LVM, LVMI (P < 0.05).Conclusions1. RF-Data technique could be used to predict cardiovascular events at the early stage. This technique is less interfered and correlated well with the traditional parameters that reflect arterial stiffness.2. In reflecting the arterial stiffness, the endovascular circumferential strain rate( EN-CSR ) , endovascular circumferential strain ( EN-CS ) changes correspond with the arterial anatomic structure and the mechanical characteristics and could be used in the early prediction of arterial stiffness and worth further investigation.3.The arterial stiffness and cardiac function correlated closely with each other in patients with hypertension. Increased stiffness is companied with decreased diastolic function of the left ventricle. The new parameter provide by RF-Data could be used to study the correlation between the arterial stiffness change and the cardiac function.