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Figure 2 Calculation of Blood Flow in the Left Circumflex Artery of a Dog With a Moderate Stenosis

In the upper part of the screen, aortic pressure (P_a) and distal coronary pressure (P_d) are shown. The blue curve in the lower part of the screen shows intracoronary temperature. On the left, blood temperature at steady-state hyperemia (T_b) is set to 0. Next, infusion of saline is started at a rate of 20 ml/min (yellow arrow). During steady-state saline infusion, temperature in the coronary artery (T) decreases by 0.85°C. Next, the sensor is pulled back to measure blood temperature to the tip of the infusion catheter (T_i) (*), which is 5.57°C below initial blood temperature. Therefore, calculated coronary blood flow = 20 x (5.57/0.85) x 1.08 = 147 ml/min (true flow measured by the flow probe was 154 ml/min in this case).