An increase in low aortic pressure increases coronary artery flow and coronary thrombolysis induced by intravenous administration of recombinant tissue plasminogen activator.
OBJECTIVE
Our study investigated the effects of an increase in aortic pressure, induced by norepinephrine (NE) administration on coronary artery flow in a clotted artery, and rate of coronary thrombolysis induced by intravenous (i.v.) administration of recombinant tissue plasminogen activator (rtPA).


METHODS
A canine model of coronary thrombosis, induced by intracoronary injection of radioactive autologous blood clots, was used to test the hypothesis that an increase in aortic blood pressure will increase coronary artery flow and the rate of clot lysis induced by i.v. administration of rtPA.


RESULTS
After clot injection, 11 dogs were phlebotomized to decrease systolic aortic pressure to 75 mm Hg. Subsequently, .25 mg/kg of rtPA was administered intravenously over two 15-minute intervals, one during hypotension, and the other after NE infusion had increased systolic blood pressure to 130 mm Hg. In six dogs the hypotensive condition was studied first, and in five dogs the NE-induced normotensive condition was studied first. In all dogs, coronary artery flow and the rate of clot lysis were significantly increased in the normotensive condition.


CONCLUSIONS
These results indicate that an increase in a low coronary artery perfusion pressure may enhance coronary artery flow and the rate of thrombolysis.
Garber
P J
PJ
Department of Medicine, University of Manitoba, Health Sciences Centre, Winnipeg, Canada.
Gu
S
S
Ducas
J
J
Schick
U
U
Prewitt
R M
RM
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology*; D003328:Coronary Thrombosis / Q000188:drug therapy / Q000503:physiopathology; D004195:Disease Models, Animal; D004285:Dogs; D004353:Drug Evaluation, Preclinical; D004359:Drug Therapy, Combination; D007262:Infusions, Intravenous; D009638:Norepinephrine / Q000008:administration & dosage; D011994:Recombinant Proteins / Q000008:administration & dosage; D015912:Thrombolytic Therapy / Q000379:methods*; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage*
D011994:Recombinant Proteins; D010959:Tissue Plasminogen Activator; D009638:Norepinephrine