Evaluation Left Ventricular Myocardial Strain Function In The Myocardial Ischemia Patients Using Speckle Tracking Imaging

[Background] Coronary atherosclerotic heart disease (CHD) is the most common type of organic involvement of atherosclerosis, and one ofthe major causes of morbidity and mortality in the world, which causes great disease burden to many countries. Myocardial ischemia caused by CHD which induces myocardial dysfuction and remodeling become a main cause of cardiac insufficiency. Therefore, precisely evaluating left ventricular myocardial function in these patients are very important. In practice, the methods used to evaluate left Ventricular function include angiocardiography, radio nuclear technology, MRI and echocardiography. Echocardiography is one of the most important techniques to assess cardiac function because of convenience, cheapness and non-invasive. However, the techniques in common use, such as M-mode echocardiography, conventional 2-dimensional echocardiography and pulse, wave Doppler echocardiography, are not sensitive enough to estimate: the subclinical left ventricular dysfunction. Although tissue Doppler imaging (TDI) could estimate subclinical lelft Ventricular dysnmction with relative high sensitivity, angle dependency limits clinical use in a way. Recently, a new technique, named speckle tracking imaging (STI), which is angle independent could estimate longitudinal, circumferential and radial function of left ventricle. Summary, necessary for further study, the application of speckle tracking imaging technology on the strain characteristics of patients with CHD.[Objective] Control coronary angiography (CAG) results, using speckle tracking imaging (STI) measurement left ventricular longitudinal strain (LS) , radial strain (RS) and the circumference strain (CS) index of patients with myocardial ischemia in CHD, quantitative analysis the characteristics of strain in myocardial ischemia. To explore the diagnostic value of strain in patients with myocardial ischemia.[Materials and Methods] Study population Subjects were enrolled referred for a clinically indicated coronary angiogram at department of cardiology, the First Affiliated Hospital of Anhui Medical University from April 2008 to October 2009. Selective coronary angiography using standard techniques was performed the same day as or the day after the echocardiography to confirm the stenosis degree of coronary arteries. 56 patients with CHD were divided into 3 groups according to Elles's CAG: Patients with angiographically diameter decrease of≥50% as the mild ischemic group A (MIa,14 cases) ; decrease of≥75% as moderate ischemic group B (MIb,24 cases) and decrease of≥98% as severe ischemic groupC (MIc, 18 cases) in the coronary arteries served. Control group (CG): 31 individuals detemined by the climcal characters, chest roemgenograms, electrocardiogram and echocardiography, and with angiographically (CAG) normal coronary arteries or diameter decrease of<30% in the coronary arteries served as the control group. The patients with AMI, symptomatic heart failure, depressed LV systolic function(1eft ventricular ejection fraction<55%), poor quality of the image, arrhyhmia, moderal to severe valvular heart diseases, congenital heart disease (CHD) , cor pulmonale and other known cardiomyopathies were all excluded from the present analysis.Echocardiography examination All subjects were examined using a commercially available echocardiogmphic system with speckle tracking imaging (STI) analysis software Qlab6.0 (IE33,PHILIPS Corp., USA) equipped with variable frequency phased-array transducer (1-5 MHz). Echocardiographic indices were obtained according to recommendation of the American Society of Echocardiogdraphy.Coronary angiography examination Coronary angiography, using philips DSA system. Multi-faceted, multi-angle selective left and right coronary angiography using the standard Judkins method. Observe and record the results of coronary artery stenosis. Statistics Statistical analyses were performed using SPSS software (SPSS 16.0 for Windows). All parametres were presented as mean±SD. Multiple comparisons were performed using ANOVA. T test was used to compare beteen the two groups, was used to compare the rate of chi-square test. Correlation analysis were performed using pearson, statistical significance was inferred for P<0.05.[Resultsl] (1) Age, gender, heart rate, LVDs, LVDd, EF and diastolic function had no significant beteen two groups (P>0.05). (2) Coronary heart disease compared with the control group segmental myocardial systolic peak RS, CS, LS was significantly lower, with statistical significance (P <0.05 or P <0.01). With the aggravation of coronary stenosis, the systolic peak circumferential strain(SP-CS) the systolic peaklongitudinal strain (SP-LS) and the systolic peak radial strain (SP-RS) curvehad a tendency of gradually decrease according to the progressive stenosis. A groups compared with the control groups had lower systolic peak strain, and some segments to reduce statistical significance (P <0.05 or P <0.01); B groups compared with the control groups significantly reduced peak systolic strain, most segments to reduce the strain was statistically significant (P <0.05 or P <0.01); C groups compared with the control groups all the segments significantly reduced peak systolic strain were statistically significant (P <0.05 or P <0.01); C groups compared with the A and B groups reduced peak systolic strain were statistically significant (P <0.05 or P <0.01). (3) Correlation analysis shows: aggravative of coronary stenosis and myocardial strain, have a good correlation; The correlation between the aggravative of coronary stenosis and strain: systolic peak circumferential strain (r=-0.543, P<0.01), systolic peak longitudinal strain: (r=-0.414, P<0.01), systolic peak radial strain, (r=-0.630, P<0.01).[Conclution] (1) Control group, the overall trend strain curve as a single peak curve, over the maximum strain before and after ECG T wave terminal (end systolic) , also gradually restored to zero at the diastolic phase. Ischemia-strain curve low and flat, or even reverse, curve disorganized, and peak time delays vary, most fall in the T wave after. (2) Different degree of stenosis of coronary heart disease (CHD) patients with left ventricular systolic function still normal, it's regional strain function has been impaired. (3) In comparison with coronary angiography results derived from the relevance of comparison, coronary artery stenosis and peak systolic strain has a good correlation. (4) Speckle tracking imaging (STI) can be an early objective quantitative evaluation of regional systolic function, determine disease on coronary heart disease has important clinical significance.