Intravascular Thermography

 

What is Thermography?

• Thermography is a catheter-based technique which detects heat released by the cells of Vulnerable (atherosclerotic) plaques.
• Atherosclerosis is an inflammatory disease and any temperature difference in activated inflammatory cells may reflect and predict plaque disruption and thrombosis.
• According to researchers, most atherosclerotic plaques showed higher temperatures compared to healthy vessel wall.
• Macrophages are metabolically very active with a high turn-over rate of total ATP content. 
• This high metabolic rate can lead to increased heat production in areas of macrophage accumulation while it cannot be observed in areas of smooth muscle cell accumulation in the absence of inflammatory cell infiltration. 
• The idea behind thermography is the fact that vulnerable plaque is a very active metabolic area.
• Independent role of thermography is limited because the structural definition obtained from high resolution imaging techniques is required.
• The necessity of a proximal balloon to provide a blood-free field is one of the limitations of this new technique. Also, plaque temperature may be affected by inflammation and variable blood flow in the lumen making the results unreliable.
• Many different types of intracoronary thermography catheters have been designed and important pathophysiological insights in the development of the unstable plaque have been obtained.

The technical characteristics of the polyamide thermistor include 

1. Temperature accuracy, 0.05°C; 
2. Time constant, 300 ms; 
3. Spatial resolution, 0.5 mm; 
4. Linear correlation of resistance versus temperature over the range of 33°C to 43°C

 

Balloon-Occluded Thermography Catheter

In (A), the thermistor is at the opposite site of the balloon. The balloon is inflated for the interruption of the flow while temperature can be recorded (B).