Application Of Strain Rate Imaging In Evaluation Of Cardiac Function With Essential Hypertension

Background and ObjectivesStrain rate and strain imaging (SRI and SI) by ultrasound are newly developed echocardiographic modality based on Doppler tissue velocity imaging (TVI) allowing quantitative assessment of regional myocardial wall deformation. SRI/SI have theoretic advantages over TVI in those SRI/SI are relatively immune to cardiac translational motion and tethering;their temporal and spatial resolutions are very high. Therefore, SRI/SI can depict and quantify systolic and diastolic deformation of regional myocardium accurately during the entire cardiac cycle. Studies indicate that SRI/SI may be superior to conventional echocardiography and TVI in quantitative assessment of regional myocardial function. The objectives of this paper are just as below: (1)To observe the characteristics of myocardial tissue velocity, strain rate (SR) and strain (s) systematically in normal subjects; (2)To assess regional systolic and diastolic function of myocardium quantitatively in patients with essential hypertensive by QTVI/SRI, and investigate the clinical feasibility of TVI/SRI. (3)To evaluate essential hypertensive patient's myocardial function using SRI and TVI parameters and compare the clinical value of these two techniques in the diagnosis.Methods and Results1. Study on characteristics of myocardial SR and S in normal subjects objectiveTo detect the strain rate (SR) and strain of left ventricle (LV) and right ventricle (RV) in healthy middle and old people using strain rate imaging (SRI),strain imaging (SI). Thirty healthy subjects were enrolled in the study .Longitudinal SR of LV walls and RV wall during systole, early diastole and atrium contraction (SRS, SRE and SRA) and largest strain (Smax) were measured. Results: (1) Longitudinal crestvalue SR of each wall: SRS of the anterior interventricular septum (AS) was lower than those of other walls except for LV lateral wall (LW), while SRS of RV latera (RW) wall larger than those of other walls. SRE of interventricular septum (IVS) and AS were lower than those of other walls, SRE of posterior wall (PW) larger than those of other walls. SRA of AS, PW, anterior wall (AW) and LW were lower than those of other walls(P<0.05). There were no significant difference between other walls. (2) SRS, SRE and SRA on each level of the base were higher than mid as well as the apex (P<0.05), while the differences between the mid and the apex were not significant. (3) Mean Smax of each wall : mean Smax of LW was lower than IVS and RW , but no significant difference was found on other walls. There was no significant difference on various levels of walls. (4)Velocity on each level of the base was higher than mid,mid higher than the apex, (P<0.05).2. Study on essential hypertensive using SRI and QTVITo evaluate essential hypertensive patient's regional myocardial function using SRI and QTVI technique. Forty patients with essential hypertensive, consisted of fourteen patients with left ventricular hypertrophy (LVH), twenty six patients without left ventricular hypertrophy (NLVH) and thirty normal control subjects in the study. The longitudinal muscular peak strain rate (SR) and peak tissues velocity(Vs,VE,VA) during systole and early diastole and atrium contraction (SRs,SRE,SRA) of left ventricular wall were measured on cardiac apex fourth chamber view, two chamber view and long axis view. Results: (1)SR: SRS of PW,IW and anterior wall (AW) in LVH group were significant lower than those of the control group (P< 0.05); all walls(SRE ) in LVH and NLVH group were significant lower than those of the control group (P< 0.05). Except for AS, SRA of other walls in LVH and NLVH group showed no significance difference compared with control group. (2) QTVI: Vs of all walls in LVH and NLVH group were not significant difference compared with control group. VE of posterior interventricular septum (PS), posterior wall (PW), anterior interventricular septum (AS) and inferior wall (IW) in NLVH group were significant lower than those of the control group (P< 0.05). Except for lateral wall of left ventriclar (LW), VE of other walls in LVH group showed significance difference compared with control group (P< 0.05); VA of PS in NLVH group was significant lower than those of the control group (P<0.05); all walls (VA ) in LVH group were significant lower than those of the control group (P<0.05). Except for lateral wall of left ventriclar (LW), VE /VA of other walls in NLVH group showed significance difference compared with control group (P<0.05), all walls in LVH group were significant difference compared with control group (P< 0.05).Conclusions(1) Spatial distribution of myocardial SR and S in healthy middle and old aged people LV are heterogeneous. Longitudinal value SR of the free walls are larger than that of the interventricular septum, longitudinal value SR of RW wall is larger than those of LV walls. Among all levels, SR are significantly higher at the base than at mid segments and apical segments. Age has obvious influence on SR during diastolic phase. There are also significant differences among longitudinal S of different walls. Smax of LW is lower than IVS and RW. There is no significant difference at various levels of walls.(2) SR of essential hypertensive patients: While left ventricular integrity systolic function is normal, regional myocardial systolic function of the LVH group are significant lower than those of control group. Regional myocardial function reduce before integrity function. Integrity and regional myocardial diastole function of left ventricular reduce before systolic function. QTVI: While left ventricular integrity systolic function is normal, regional myocardial systolic function of essential hypertensive patients I is not detected regional myocardial function reduction. When most of ventricular walls appeared regional myocardial diastolic function reduction,left ventricular integrity diastolic function also reduced.(3) SRI/QTVI can evaluate regional myocardial diastole and systolic function in longitudinal direction noninvasively and quantitatively, and can be used as new technique for detecting regional myocardial dysfunction of essential hypertensive patients. Compared QTVI and SRI in evaluation of regional function of the left ventricular with essential hypertension, SRI are more sensitive than TVI in detecting regional myocardial systolic dysfunction, indicating that SRI have important clinical application values.