Abstract 3422: In vivo Measurement of Heat Energy in Human Coronary Arterial Segments: A New Method for Functional Evaluation of High Risk Plaques
Several methods have been applied for functional assessment of atheromatic plaques. The main limitations include the evaluation of a single plaque and not arterial segment, and the cooling effect of blood flow. We present a new method for the measurement of heat energy (Q), produced at diseased coronary arterial segments in patients with coronary artery disease.
Methods: We included patients with stable angina (SA) or acute coronary syndromes (ACS) undergoing percutaneous coronary intervention. The region of interest (ROI) was designated as 5mm proximally (T1) to 5mm distally (T2) to the culprit lesion. According to the first law of thermodynamics Q = Cp x mass (m) x change in temperature of blood between T2 and T1 (ΔT) (figure⇓). Cp is a constant and m = 1060 kg/m3 x v x A (v = velocity; A = area at point T1). Area was measured by quantitative coronary angiography. A flow wire was then advanced to the ROI and we measured v at point T1. For ΔT measurement we used a highly sensitive wire (Radi Medical Systems, Sweden). We then calculated Q in kWatt.
Results: We enrolled 19 patients: 10 with SA and 9 with ACS. The procedure was safe and uncomplicated. Mean Q was 0.40±0.38 kWatt. The baseline angiographical characteristics were similar between the two groups. There were no differences in mean v and A between the groups. ΔT was higher in patients with ACS. Therefore, mean Q was higher in patients with ACS compared to patients with SA (0.66±0.31 vs 0.24±0.33 kWatt, p=0.03).
Conclusions: The present study introduces a new method for functional assessment of coronary arterial segments. The first human application demonstrated that heat energy is increased in culprit arterial segments in patients with ACS.