Myocardial tactile stiffness

背景。局部心肌收缩功能的评价具有重要的临床意义。我们开发了一种新的触觉传感器系统，用于精确测量心肌原位刚度。我们发现，通过这种传感器测量的心肌刚度，我们称之为触觉刚度，可以是一个非常有用的指标，用于精确量化区域心肌功能。在本研究中，我们采用冠状动脉狭窄模型研究冠状动脉血流减少条件下局部心肌触觉刚度。测定5只15 ~ 17 kg开胸杂种狗心肌触觉刚度、冠状动脉血流量、心室压和容积。测量基线心肌硬度后，用球囊闭塞器诱导冠状动脉狭窄。将冠状动脉血流降低至基线水平的50%和25%，可显著降低收缩期末触觉刚度，分别从2.20±0.16 g/mm2降至2.05±0.20 g/mm2 （p < 0.05）和从2.21±0.16 g/mm2降至1.96±0.18 g/mm2 （p < 0.01）。降低血流至50%和25%时，舒张末期僵硬度分别从1.29±0.15 g/mm2和1.30±0.16 g/mm2显著升高至1.46±0.14 g/mm2 （p < 0.01）。结论。我们认为，在冠状动脉血流减少的情况下，区域心肌触觉刚度将是一个有用的指标，足够敏感，可以检测区域收缩功能的变化。

Background. Evaluation of regional myocardial contractile function is of clinical importance. We have developed a new tactile sensor system for accurate measurement of myocardial stiffness in situ. We found that thc myocardial stiffness measured by this sensor, which we call tactile stiffness, can be a very useful index for accurate quantification of regional myocardial function. In this study, we used a coronary stenosis model to investigate regional myocardial tactile stiffness under conditions of reduced coronary blood flow.Methods. The myocardial tactile stiffness, coronary blood flow, and ventricular pressure and volume, of five open chest mongrel dogs weighing 15 to 17 kg, were measured. After measuring the baseline myocardial stiffness, coronary arterial stenosis was induced with a balloon occluder.Results. Reducing the coronary flow to 50% and 25% of the baseline level reduced the end-systolic tactile stiffness significantly from 2.20 ± 0.16 g/mm2 to 2.05 ± 0.20 g/mm2 (p < 0.05) and from 2.21 ± 0.16 g/mm2 to 1.96 ± 0.18 g/mm2 (p < 0.01), respectively. Reducing the flow, to 50% and 25%, increased the end-diastolic stiffness significantly from 1.29 ± 0.15 g/mm2 to 1.39 ± 0.14 g/mm2 (p < 0.01) and from 1.30 ± 0.16 g/mm2 to 1.46 ± 0.14 g/mm2 (p < 0.05), respectively. Conclusions. We consider that the regional myocardial tactile stiffness will be a useful index sensitive enough to detect changes in regional contractile function under conditions of reduced, coronary blood flow.