Influence of catheter design on lumen wall temperature distribution in intracoronary thermography

Intracoronary thermography is a currently used vulnerable plaque detection method. We studied how catheter design and catheter location influence the temperature readings, and thus its capacity to detect vulnerable plaques. Finite element calculations were performed on geometries representing the coronary artery, the vulnerable plaque and the catheter. Catheter material, diameter and location with respect to the plaque were varied. Both flow and no-flow situations were studied. Maximal lumen wall temperature difference without a catheter (ΔT=0.12°C, flow=75cm3 min−1) was considered the reference. Presence of a 1.0mm nitinol catheter right under the plaque increased ΔT to 0.14°C, whereas a 1.0mm polyurethane catheter increased ΔT to 0.51°C. The location at which a thermosensitive element should be placed for most optimal temperature readings during a pullback was shown to lie at the catheter edge for the nitinol catheter and at 1.1mm from the catheter edge for the polyurethane catheter. Temperature readings decreased to background temperature when the catheter was in close proximity but not overlapping the plaque. ΔT decreased approximately by 70% when a gap of 0.2mm existed between the catheter and the lumen wall. Occlusion of blood flow increased ΔT values in all cases, but most pronounced for nitinol catheters. A polyurethane catheter increased the temperature readings, since its heat conductivity is lower than that of blood, which makes it a very good choice for heat source detection. Catheter design can contribute to enhanced temperature readings and thus can enable more optimal vulnerable plaque detection.