In vitro and in vivo studies on thermistor-based intracoronary temperature measurements: effect of pressure and flow.
BACKGROUND
Intracoronary thermography has been proposed to detect vulnerable plaques. We hypothesized that changes in coronary pressure and flow in the coronary tree may interfere with the temperature measurements obtained with thermistors.


RESULTS
First, a very close correlation was found in vitro between the temperature measured by a thermocouple and by a thermistor-based temperature measuring guide wire (PressureWire, PW) over a large temperature range. Second, the PW was tested in a vitro low pressure model of "hot plaque". The sensor of the PW could detect changes in temperature of the wall of 0.5 degrees C as long as the distance from the wall was less than 0.5 mm and the flow less than 60 mL/min. Third, in 18 patients with an acute myocardial infarction, intracoronary pressure and temperature variations were assessed. Although crossing the occlusion, the temperature rose by 0.059 +/- 0.02 degrees C and this increase was correlated with the distal coronary pressure (r = 0.72, P < 0.001). Fourth, a balloon coronary occlusion (BCO) with the sensor distally in the distal part of the vessel (low flow/low pressure conditions) systematically induced an increase in temperature (0.14 +/- 0.07 degrees C) while with the sensor proximally to the balloon occlusion (low flow/normal pressure conditions), no change occurred.


CONCLUSIONS
Taken together these observations suggest that thermistor-based sensors are not suited for assessing thermal heterogeneity in the vascular wall and that the data obtained so far in patients with acute coronary syndromes might have been flawed by pressure (and flow) artifacts.
Cuisset
Thomas
T
Cardiovascular Center, OLV Hospital, Aalst, Belgium.
Beauloye
Christophe
C
Melikian
Narbeh
N
Hamilos
Michalis
M
Sarma
Jaydeep
J
Sarno
Giovanna
G
Naslund
Maria
M
Smith
Leif
L
Van de Vosse
Frans
F
Pijls
Nico H J
NH
De Bruyne
Bernard
B
D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation; D001011:Aorta / Q000503:physiopathology; D016477:Artifacts; D021721:Balloon Occlusion; D001794:Blood Pressure; D001831:Body Temperature; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D003331:Coronary Vessels / Q000503:physiopathology*; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D015607:Stents; D013817:Thermography / Q000295:instrumentation*; D013997:Time Factors