Changes in purine nucleoside content in human myocardial efflux during pacing-induced ischemia.

Pacing-induced myocardial ischemia in 18 patients resulted in an increase of coronary sinus hypoxanthine levels from 1.20 +/- 0.18 micron during control to 2.41 +/- 0.52 micron (p less than 0.025) during pain. In addition, early lactate production occurred frequently before angina was noted. Neither hypoxanthine nor lactate levels changed in seven nonanginal patients, nor were significant alterations in potassium, inorganic phosphate, glucose, or oxygen saturation found in all patients. Myocardial hypoxanthine production seems a useful indicator of ischemia in the human heart.