| Normal myocardial systolic and diastolic function entirely relied on the sufficient energy generated from oxidative metabolism. Physiologically, capillary networks were extremely rich in myocardium (approximately 4000 unit capillary/mm3), especially in subendomyocardial layer. Microangiopathy was a characteristic pathological change in type 2 Diabetes Mellitus(DM). Capillary basement membrane thickening, microaneurysm and microvessel dysfunction were typical pathological changes of diabetic microangiopathy. The incidence of vascular complications in T2DM was 2~3 times than the normal population, which is one of the leading cause of mortality and disability. The microvascular pathology in heart led to diabetic myocardiopathy. A large number of studies had shown that myocardial systolic and diastolic dysfunction were closely related with myocardial microcirculation. In this study, we sought to assess the microcirculation perfusion and function of left ventricle myocardium quantitatively in 2 type DM by Real-time Myocardial Contrast Echocardiography (RT-MCE) and 2D-STI (Two-dimensional Strain Imaging). Then explore the relations between perfusion and function further. We tried to discover variables in early stage of diabetic myocardial lesion for guiding the treatment and prognosis clinically. This study was composed by two parts: Part 1. Primary Study on Rest Global Myocardial Perfusion of left ventricular in Type 2 Diabetes Mellitus patients with Real-time Myocardial Contrast EchocardiographyObjective The purpose of this part was to explore the characteristics of rest myocardial perfusion of type 2 diabetes mellitus by RT-MCE. Methods 16 patients with T2DM and 12 in control were enrolled in the study. RT-MCE was performed using a continuous infusion of Sonovue with vena mediana in elbow. Images of left ventricle filled with contrast were acquired from apical 4- , 2-chamber and long axis views with real-time myocardial contrast mode of GE Vivid 7 dimension system. All above images were captured in continuous 3 cardiac cycles before "flash", and then 15 cardiac cycles after "flash". All clips were stored for off-line analysis. Results①There was no significant difference in contrast filling intensity between disease and control group with naked eyes. A value in T2DM patients was slight statistic lower than that in control (A: 6.45±1.39 vs 6.84±1.80;P<0.05). There were significant decrease on indices ofβand A×βin patients, compared with control group. (k:1.07±0.30 vs 1.23±0.32;A×β: 6.90±2.58 vs 8.40±3.06;P<0.01, respectively).Part 2. Assessment of Left Ventricular Subendomyocardial perfusion and regional function in patients with Type 2 Diabetes Mellitus Using Real-time Myocardial Contrast Echocardiography Combined with Two-dimensional Strain ImagingObjective The purpose of this part was to evaluate the subendomyocardial perfusion and regional function of T2DM and relationship between them by RT-MCE combined with 2D-STI. Methods RT-MCE was performed using a continuous infusion of Sonovue with vena mediana in elbow. Images of ventricle filled with contrast were acquired from apical 4- , 2-chamber and long axis views with real-time myocardial contrast mode of GE Vivid 7 dimension system. All above images were captured in continuous 15 cardiac cycles before and after "flash". All clips were stored for off-line analysis. Applying with workstation, peak velocity of longitudinal strain and strain rate in systole and diastole, and indices of A,β, A×βin global and regional myocardium were collected. Results①Indices A,β, and A×β(A: 4.99±1.52 vs 7.08±1.45;β: 1.11±0.31 vs 1.41±0.32;A×β: 5.66±2.59 vs 10.05±3.27;P<0.011, respectively) were significantly lower in subendomyocardial layer of T2DM than those in control (P<0.01, respectively).②The indices of A,β, and A×βwere significantly lower in subendomyocardium than those in global myocardium (P<0.01, respectively).③Compared the indices in control, T2DM patients had a significantly decrease in systolic SL, early diastolic SRLe and late diastolic SRLa(P<0.01, respectively).There was no significant difference of systolic SRLs in T2DM and control.④Index of A×βhad significantly correlations with SL and SRLa in T2DM (P<0.001).CONCLUSIONS:①In quiescent condition, there were abnormal global myocardial perfusion in T2DM .②Compared with control group, there was low perfusion with subendomyocardium in T2DM. Compared with global myocardium, there was statistically lower perfusion with subendomyocardium. That inferred that ischemia in subendomyocardium was more serious than in global myocardium. Subendomyocardial ischemia would lead to regional myocardial dysfunction.③There were significant positive correlations between A×βin RT-MCE and SL, SRLa in 2D-STI. It illustrated that subendomyocardial blood flow reduced and regional myocardial function decreased correspondingly in T2DM,.
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