The coronary hemodynamic effects of controlled aortic insufficiency (Al) were studied in 10 dogs. Coronary blood flow (CBF), before and during reactive hyperemia (RH) with graded coronary diameter narrowings (CN), aortic (Ao) and left ventricular (LV) pressures (P), and aortic blood flow (AoF) were recorded. Opening an adjustable basket catheter, positioned across the aortic valve, created reversible Al quantitated from phasic AoF. AI was regulated so that mean CBF was similar with or without Al. During Al, eart rate and systolic AoP were unchanged, but diastolic AoP declined 14 mm Hg (mean) and end-diastolic LVP increased 8 mm Hg, both p < 0.05. With CN 85%, mean CBF decreased with or without Al. Coronary resistance was similar with or without Al. During Al with' no CN, peak RH CBF declined ignificantly and was similar to peak RH with 70% CN without Al. Furthermore, Al with 60% CN caused additional reduction in peak RH and was similar to peak RH with 80% CN without Al.
These data suggest that CBF reserve, exposed during RH, is decreased during Al. With Al, a given CN has coronary hemodynamic properties similar to higher degrees of CN without Al. These results may relate to clinical findings of ischemia in patients w,ith Al and no or moderate CN.