Ultrasonic attenuation of myocardial tissue: dependence on time after excision and on temperature.

The ultrasonic attenuation coefficient of myocardium over the frequency range 2-10 MHz has been measured in vitro as a function excision and as a function of temperature. Results indicate that the attenuation coefficient was approximately independent of time for 4 h following excision at 19.5 degrees C, but increased by about 20% over a 4-h interval at 35 degrees C. The attenuation coefficient decreases approximately linearly with increasing temperature over the range 20.5 degrees -37 degrees C, with the value at 37 degrees C being about 20% lower than at 20.5 degrees C.