Deleterious cardiac effects of captopril during acute myocardial ischaemia in the dog.
OBJECTIVE
The aim was to evaluate the effects of the angiotensin converting enzyme inhibitor captopril on acute myocardial ischaemia.


METHODS
Seventeen anaesthetised open chest dogs were randomised to 3 minute angioplasty balloon occlusions of the left circumflex coronary artery before and after intravenous infusion of captopril (n = 8) or placebo (n = 9).


RESULTS
There was apparent worsening of ischaemia during balloon inflation after captopril infusion, when compared with control inflation, as suggested by further ST segment elevation of 1.8 (SD 1.8) mm, p less than 0.03, and by further lowering of regional myocardial pH [-0.05(0.05), p = 0.06], and peak positive and peak negative dP/dt [-439(337)mm Hg.s-1, p less than 0.008; -470(316) mm Hg.s-1, p less than 0.004, respectively]. The increase in ischaemia occurred despite reduced double product after captopril administration. Regional myocardial blood flow in the ischaemic artery distribution was lower during post captopril balloon occlusion [-0.1(0.06) ml.min-1.g-1, p less than 0.005] than during control balloon inflation, while coronary vascular resistance increased by 161(172)% (range 45 to 497%, p less than 0.04). There were no significant differences in ST segments, pH, haemodynamic variables, or blood flow during balloon inflations before and after saline infusion.


CONCLUSIONS
Despite lower myocardial metabolic demands, acute intravenous administration of captopril was associated with increased ischaemia during transient coronary artery occlusion.
Alam
S
S
Department of Medicine, American University of Beirut Medical Center.
Rezkalla
S
S
Farkas
P
P
Turi
Z G
ZG
D000208:Acute Disease; D015906:Angioplasty, Balloon, Coronary / Q000379:methods*; D000818:Animals; D002216:Captopril / Q000009:adverse effects* / Q000494:pharmacology; D003327:Coronary Disease / Q000378:metabolism / Q000503:physiopathology*; D004195:Disease Models, Animal; D004285:Dogs; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D008297:Male; D009206:Myocardium / Q000378:metabolism; D012039:Regional Blood Flow / Q000187:drug effects
D002216:Captopril