Effect of calcium entry and beta blockade during infrarenal aortic clamping.
Clamping and declamping during aortic surgery produce a hemodynamically significant myocardial stress. The cardiovascular (CV) response to this stress may be adversely altered by calcium antagonists and beta-adrenoreceptor blockade employed to control symptomatic coronary artery disease. This study evaluated the effect of verapamil (V), propranolol (P), and their combination (P + V) on the CV response to infrarenal abdominal aortic cross-clamping and declamping in anesthetized dogs. Six dogs received P as a bolus of 0.5 mg/kg 20 min before clamping. Six additional dogs received V as a 300 micrograms/kg bolus followed by a V infusion of 6 micrograms/kg/min for 20 min before clamping. A third group of six dogs received the P bolus followed 20 min later by the V regimen (P + V). In both the V and P + V groups, 6 micrograms/kg/min V was infused throughout the clamping and declamping sequence. A fourth group of six control dogs received no cardioactive drugs during the experiment. Heart rate, mean aortic blood pressure, left ventricular end-diastolic pressures, peak rate of rise of left ventricular pressure, cardiac output, and systemic vascular resistance were measured in all animals before aortic cross-clamping, at 5 and 40 min after clamping, and 5 min after declamping. The results demonstrated additive negative chronotropic and inotropic properties of P + V therapy with a more significantly adverse effect than that of either drug alone. The implications of this study warrant added caution when patients treated with these drugs undergo abdominal aortic surgery.
Lalka
S G
SG
Department of Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106.
Rhodes
R S
RS
Lina
A A
AA
Derrer
S
S
Jezeski
R
R
Dauchot
P J
PJ
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001012:Aorta, Abdominal / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003250:Constriction / Q000009:adverse effects; D003327:Coronary Disease / Q000503:physiopathology; D004285:Dogs; D004347:Drug Interactions; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D009200:Myocardial Contraction / Q000187:drug effects; D011433:Propranolol / Q000494:pharmacology; D013997:Time Factors; D014700:Verapamil / Q000494:pharmacology
D000319:Adrenergic beta-Antagonists; D002121:Calcium Channel Blockers; D011433:Propranolol; D014700:Verapamil