Figure 1.

A, effect of elevating coronary perfusion pulse pressure (PP) on coronary flow under basal conditions. CorP, coronary pressure; CorF, coronary flow in the left anterior descending arterial bed. The sudden change to a higher PP (arrow) was accompanied by a modest but stable rise in mean flow, averaging 11%. B, synergy of adenosine and PP on coronary flow augmentation. Data are from the same heart as shown in A. Adenosine was first administered i.c. to raise baseline flow by 21% and then PP was increased similarly. In this case, there was a marked rise in coronary flow, peaking at 3.3 times baseline after 25 s, and reaching a plateau at a steady-state value 2.2 times that of the control.