Effect of acidosis on patients with myocardial ischemia.

Reduction in pH is known to decrease O2 affinity (Bohr effect) and increase the rate of O2 release from blood. It provides a potential mechanism for increasing O2 transport to the myocardium. Fifteen patients with refractory, chronic angina were studied by treadmill exercise tolerance tests and whole blood-oxygen release rate measurements before and 4 days after beginning treatment with oral acetazolamide (10 to 20 mg/kg body weight). Positive treadmill exercise test or myocardial necrosis was present in each case. There was a correlation between an increased O2 release rate from blood and relief of symptoms. The major side effect in 2 patients with pathologic fatigue believed to result from acidosis. Of the 7 patients who obtained relief from angina, in each there was a 27% increase in the rate of release of O2 from their whole blood. Seven patients did not obtain relief; they showed no change in the rate of release. In the 4 patients who became worse the rate of deoxygenation decreased by 22%. All changes in deoxygenation rate coincided with the clinical findings. The treatment of ischemic heart disease with acetazolamide or other acidifying agents should not, however, be attempted until further investigation establishes their clinical value.