The effect of reduced blood-flow on the coronary wall temperature. Are significant lesions suitable for intravascular thermography?

Abstract

The purpose of this study was to investigate the relation between acute coronary flow reduction and arterial wall temperature. Five pigs with normal coronary arteries were catheterized. Arterial wall temperature was studied with a thermographic system that uses a 4-thermistor sensor tip. Flow velocity was studied at the same time and place with the temperature measurements, using a Doppler wire. In order to modify the coronary flow, a balloon was gradually inflated proximally to the thermographic sensors. Temperature differences and flow velocities were simultaneously recorded. Flow velocities above an average peak velocity (APV) of 9 cm/s were associated with unaffected temperature measurements. At flow velocities around 4 cm/s, the wall temperature was increased (deltaT=0.015+/-0.005 degrees C, P approximately 0.05), following the heart-rate. When flow velocity dropped further below this value, the local wall temperature was logarithmically increased to a maximum value observed at total vessel occlusion (deltaT=0.188+/-0.023 degrees C, P<0.001). The reduction of coronary flow has an effect on the arterial wall temperature. This effect however, appears only below a critical threshold of APV and in a logarithmic fashion. Above this threshold, temperature measurements should be unaffected from flow reductions and related to the regional temperature heterogeneity.