The relationship between vulnerability of coronary atherosclerotic plaque and downstream myocardial perfusion and myocardial strain in mice / 中华超声影像学杂志

ABSTRACT

Objective:To investigate the relationship between vulnerability of mouse coronary artery plaque and downstream myocardial perfusion and myocardial strain.Methods:Thirteen ApoE knockout mice with stable coronary plaques (stable plaque group)and 13 ApoE knockout mice with vulnerable coronary plaques(vulnerable plaque group) were selected as the experimental group, and 15 sex- and age-matched C57BL/6 mice with the same genetic background as ApoE mice were chosed as the control group. Myocardial contrast echocardiography (MCE) was carried out to quantify regional myocardial perfusion at rest and during adenosine stress using a Vevo 2100 system (Visual sonics). Replenishment curves of myocardial contrast were obtained, and rates of signal rise (β) and plateau intensity (A) were recorded. MBF was estimated by the product of A and β. Speckle tracking imaging combined with adenosine stress test was used to evaluate the longitudinal strain of left ventricular myocardium in mice. The vulnerability of the plaque was assessed by histopathology in serial tissue sections of proximal and middle left coronary artery according to the previously reported method.Results:There were no significant differences in body weight, heart rate, left ventricular end diastolic volume, left ventricular end systolic volume, left ventricular mass and ejection fraction among the three groups( P>0.05). The levels of serum triglyceride, total cholesterol, high density lipoprotein and low density lipoprotein in stable plaque group and vulnerable plaque group were significantly increased when compared with those in control group (all P<0.05). The pathological results showed that the coronary luminal stenosis rates in the stable plaque group and the vulnerable plaque group were (74.3±4.9)% and (75.5±7.1)% respectively, with no significant difference between the two groups( P>0.05). MBF of the middle anterior septum and left ventricular posterior wall in the experimental groups were significantly decreased when compared with that in the control group both in the resting status and during adenosine stress(all P<0.05). There were no significant differences in the MCE parameters between the stable plaque group and the vulnerable plaque group at rest( P>0.05). However, during adenosine stress, MBF of the vulnerable plaque group was decreased more significantly than that of the stable plaque group ( P<0.05). Compared with the control group, the values of longitudinal strain of the left ventricle in both experimental groups were decreased during resting status, without statistical significance (all P>0.05), but decreased significantly during adenosine stress and with more decrease in the vulnerable plaque group (all P<0.05). Conclusions:For the same degree of coronary artery stenosis in mice, the coronary artery vulnerable plaque group has less downstream myocardial perfusion and myocardial strain than the stable plaque group during adenosine stress. That is, the plaque vulnerability can affect the downstream myocardial perfusion and myocardial strain in the mouse model.