OBJECTIVES: This study investigated whether temperature measurements are influenced by blood flow. BACKGROUND: Previous ex vivo studies showed marked thermal heterogeneity in atheromatic plaques. In stable lesions, however, trivial in vivo temperature variations are recorded, perhaps due to the "cooling effect" of blood flow. METHODS: Eighteen patients with effort angina were studied. Coronary flow velocity was continuously recorded; over another guidewire, temperature measurements were performed at the proximal vessel wall and at the lesion before, during, and after complete interruption of blood flow by inflation of a balloon. The DeltaTp was assigned as the difference between the proximal vessel wall temperature and the maximal temperature during and after balloon inflation. The DeltaTl was assigned as the difference between the atherosclerotic plaque and the proximal vessel wall. RESULTS: The procedure was not complicated. During and after complete interruption of flow, DeltaTp was 0.012 +/- 0.01 degrees C and -0.006 +/- -0.01 degrees C (p < 0.001), respectively. The DeltaTl was 0.08 +/- 0.04 degrees C at baseline and went to 0.18 +/- 0.05 degrees C (60.5 +/- 14.1% increase) during and 0.08 +/- 0.04 degrees C after flow interruption (p < 0.001). The DeltaTl was greater than DeltaTp during and after impairment of flow (p < 0.001). A correlation between the baseline average peak velocity and DeltaTl during flow interruption was found (R = 0.57, p = 0.01). In seven patients thermal heterogeneity was not detected at baseline, and during balloon inflation DeltaTl increased by 76.0 +/- 8.4%. CONCLUSIONS: Thermal heterogeneity is underestimated in atherosclerotic plaques in patients with effort angina. Potential in vivo underestimation of heat production locally in human atherosclerotic is due to the "cooling effect" of coronary blood flow.
OBJECTIVES: This study investigated whether temperature measurements are influenced by blood flow. BACKGROUND: Previous ex vivo studies showed marked thermal heterogeneity in atheromatic plaques. In stable lesions, however, trivial in vivo temperature variations are recorded, perhaps due to the "cooling effect" of blood flow. METHODS: Eighteen patients with effort angina were studied. Coronary flow velocity was continuously recorded; over another guidewire, temperature measurements were performed at the proximal vessel wall and at the lesion before, during, and after complete interruption of blood flow by inflation of a balloon. The DeltaTp was assigned as the difference between the proximal vessel wall temperature and the maximal temperature during and after balloon inflation. The DeltaTl was assigned as the difference between the atherosclerotic plaque and the proximal vessel wall. RESULTS: The procedure was not complicated. During and after complete interruption of flow, DeltaTp was 0.012 +/- 0.01 degrees C and -0.006 +/- -0.01 degrees C (p < 0.001), respectively. The DeltaTl was 0.08 +/- 0.04 degrees C at baseline and went to 0.18 +/- 0.05 degrees C (60.5 +/- 14.1% increase) during and 0.08 +/- 0.04 degrees C after flow interruption (p < 0.001). The DeltaTl was greater than DeltaTp during and after impairment of flow (p < 0.001). A correlation between the baseline average peak velocity and DeltaTl during flow interruption was found (R = 0.57, p = 0.01). In seven patients thermal heterogeneity was not detected at baseline, and during balloon inflation DeltaTl increased by 76.0 +/- 8.4%. CONCLUSIONS: Thermal heterogeneity is underestimated in atherosclerotic plaques in patients with effort angina. Potential in vivo underestimation of heat production locally in humanatherosclerotic is due to the "cooling effect" of coronary blood flow.
Authors: Shriram Sethuraman; Salavat R Aglyamov; Richard W Smalling; Stanislav Y Emelianov Journal: Ultrasound Med Biol Date: 2007-10-23 Impact factor: 2.998