Thermal heterogeneity in stable human coronary atherosclerotic plaques is underestimated in vivo: the "cooling effect" of blood flow.
OBJECTIVE
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.
Stefanadis
Christodoulos
C
Department of Cardiology, Hippokration Hospital, Athens Medical School, Athens, Greece. cstefan@cc.uoa.gr
Toutouzas
Konstantinos
K
Tsiamis
Eleftherios
E
Mitropoulos
Ioannis
I
Tsioufis
Costas
C
Kallikazaros
Ioannis
I
Pitsavos
Christos
C
Toutouzas
Pavlos
P
D000368:Aged; D000787:Angina Pectoris / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology; D001831:Body Temperature / Q000502:physiology*; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003326:Coronary Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D013817:Thermography