A, B and C: correlation between heart rate and MBF is shown in a two-drug comparison. As shown in 7A, adenosine has a parallel upward shift ie. a higher MBF for the same heart rate, compared to dipyridamole. In contrast, regadenoson has an upward and rightward shift i.e. higher MBF and heart rate when compared to dipyridamole and adenosine as shown in 7B and C respectively.