介入超声印压系统对活体舒张心肌黏弹性的检测作用

目的 探讨介入超声印压系统(IUIS)对活体心脏舒张期舒张心肌黏弹性的检测作用.方法 应用IUIS以印压法对陈旧性心肌梗死模型组(OMI组,n=8)和假手术组(n=8)犬在舒张期进行印压蠕变实验,以三参量固体黏弹性模型拟合实验数据,提取舒张心肌瞬时弹性模量(E1)、松弛模量(E∞)、蠕变弹性模量(E2)、黏性阻尼系数(η)等黏弹性参数,并进行比较.结果 OMI组E1、E∞、E2、η参数(分别为27.81±6.74kPa、17.87±3.59kPa、49.54±14.35kPa、1.97±0.78Pa.s)与假手术组(分别为6.78±2.43kPa、4.52±1.56kPa、16.82±12.37kPa、0.66±0.40Pa.s)比较均明显增加,差异有统计学意义(P<0.05).结论 IUIS系统及其印压蠕变实验方法 可用于活体舒张心肌黏弹性的评估.三参量固体黏弹性模型可用于描述舒张心肌蠕变特性.梗死心肌弹性模量和黏性阻力增加.

Detection of the viscoelasticity of relaxed myocardium in vivo by intervention ultrasound indentation system

Objective To explore the viscoelasticity of relaxed myocardium in vivo through indentation method with an intervention ultrasound indentation system (IUIS). Methods Old myocardial infarction (OMI) models of canine were established by ligating left anterior descending branch of coronary artery for 3 months. The indentation creep tests were used respectively in OMI group and shame group (n=8, each) by IUIS in middle and advanced diastole stage in vivo. Test data were processed with three-parameter solid viscoelasticity model, and the viscoelastic parameters, such as instantaneous elastic modulus (E1), relaxation modulus (E∞), creep elastic modulus (E2) and viscous damping coefficient (η) in normal and infarcted myocardium were obtained and compared. Results All the parameters of E1, E∞, E2 and η increased obviously in OMI group than in sham group shown as follows: 27.81±6.74kPa vs. 6.78±2.43kPa; 17.87±3.59kPa vs. 4.52±1.56kPa; 49.54±14.35kPa vs. 16.82±12.37kPa and 1.97±0.78Pa.s vs. 0.66±0.40Pa.s. The differences were statistically significant (P<0.05). Conclusions IUIS is a feasible method to assess the viscoelasticity of relaxed myocardium in vivo. Three-parameter viscoelasticity model can be used to describe creep properties of relaxed myocardium. Both elastic modulus and viscosity resistance have increased in infarcted myocardium.