The effect of rapid decreases of blood pressure by different mechanisms on coronary flow and flow reserve in normal coronary arteries

39 patients total: 20 patients with coronary artery disease (measurements in normal left circumflex) and 19 patients without coronary artery disease (measurements in normal left anterior descending).

Intravenous nitroprusside (0.5 to 2 microg/kg/min) and nitroglycerin (10 to 90 microg/min) titrated to decrease mean blood pressure 20% to 25% (in CAD group); intravenous clonidine 150 microg in 5 min (in non-CAD group).

Baseline measurements before drug administration.

Coronary flow reserve (CFR), coronary blood flow (CBF), and time-averaged peak velocity (APV) measured using Doppler wire at rest and during hyperemia.surrogate