Myocardial tactile stiffness during acute reduction of coronary blood flow

Background. Evaluation of regional myocardial contractile function is of cl inical importance, We have developed a new tactile sensor system for accura te measurement of myocardial stiffness in situ. We found that the myocardia l stiffness measured by this sensor, which we call tactile stiffness, can b e a very useful index for accurate quantification of regional myocardial fu nction. In this study, we used a coronary stenosis model to investigate reg ional myocardial tactile stiffness under conditions of reduced coronary blo od now. Methods. The myocardial tactile stiffness, coronary blood flow, and ventric ular pressure and volume, of five open chest mongrel dogs weighing 15 to 17 kg, were measured. After measuring the baseline myocardial stiffness, coro nary arterial stenosis was induced with a balloon occluder. Results. Reducing the coronary flow to 50% and 25% of the baseline level re duced the end-systolic tactile stiffness significantly from 2.20 +/- 0.16 g /mm(2) to 2.05 +/- 0.20 g/mm(2) (p < 0.05) and from 2.21 +/- 0.16 g/mm(2) t o 1.96 +/- 0.18 g/mm(2) (p < 0.01), respectively. Reducing the now, to 50% and 25%, increased the end-diastolic stiffness significantly from 1.29 +/- 0.15 g/mm(2) to 1.39 +/- 0.14 g/mm(2) (p < 0.01) and from 1.30 +/- 0.16 g/m m(2) to 1.46 +/- 0.14 g/mm(2) (p < 0.05), respectively. Conclusions. We consider that the regional myocardial tactile stiffness wil l be a useful index sensitive enough to detect changes in regional contract ile function under conditions of reduced coronary blood flow. (C) 2000 by T he Society of Thoracic Surgeons.