Figure 1.

Principles of measurement of reactive hyperaemia and flowmotion using laser Doppler flowmetry. (a) Original Doppler tracing in a patient over a time period of 11 minutes (3 minutes pre-ischaemic, 5 minutes ischaemia, 3 minutes reperfusion time). The area under the curve (AUC) was calculated for each time interval. 1 = AUC pre-ischemic; 2 = AUC during ischaemia; 3 = AUC during reactive hyperaemia; 1 + 3 = AUC during reperfusion. (b) Twenty seconds of an original Doppler tracing with superimposed fast Fourier transformation. Computed analysis of the original plot reveals two oscillations with different frequencies representing heart rate and flowmotion.