Curves of blood flow in coronary sinus. Blood flow was measured using phase-contrast cine CMR. Blue and red lines, blood flow at rest and during ATP infusion, respectively. Coronary sinus blood flow increased about 4-fold in this patient during ATP infusion (rest vs. ATP infusion: = 70 vs. 266 mL/min; CFR = 3.8). ATP, adenosine triphosphate; CFR, coronary flow reserve; CS, coronary sinus.