Abstract
Myocardial dysfunction has been reported in cyanotic congenital heart disease (CCHD) patients. One possible cause of this abnormality could be recurrent episodes of myocardial hypoxia during periods of high myocardial O2 demand. Accordingly an animal model was developed to produce systemic hypoxemia with a teflon graft used to shunt the inferior vena caval return to the left atrium. Left ventricular pressure (LVP), dP/dt, aortic pressure, heart rate (HR), pO2, ph, pO2, and arterial (a) and coronary sinus (cs) lactate (LAC) levels were measured before and after atrial pacing (AP) and isoproterenol (ISU) Infusion in shunted and control dogs. In four control animals (pO2 39-58mmHg) subjected to AP, HR increased from 147 to 233/min while LAC(a-cs) did not change significantly (0.9 to 1.4meq/L); with ISU there was also no change in LAC (0.9meq/L) despite an increase in HR and dP/dt from control. Five cyanotic animals (pO224-30mmHg) also showed no significant change in LAC(a-cs) with AP (0.9 to 1.1meq/L) but all dogs showed lactate production (LAC(a-cs)=-0.6meq/L) with ISU infusion. These data indicate that myocardial hypoxia can be produced in a cyanotic animal model during times of high myocardial O2 demands at pO2 levels commonly seen in patients with CCHD. Thus myocardial hypoxia may play a role in the ventricular dysfunction seen in children with CCHD.
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Graham, T., Buckspan, G. & Fisher, R. MYOCARDIAL HYPOXIA DURING ISOPROTERENOL INFUSION IN AN ANIMAL MODEL: POSSIBLE CAUSE OF MYOCARDIAL DYSFUNCTION IN CYANOTIC CONGENITAL HEART DISEASE. Pediatr Res 11, 392 (1977). https://doi.org/10.1203/00006450-197704000-00138
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DOI: https://doi.org/10.1203/00006450-197704000-00138