The effect of glucagon on myocardial metabolism in diagnostic cardiac pacing.

Nine patients with the angina pectoris syndrome in the absence of a history of demonstrable myocardial infarction were examined twice at rest and during cardiac pacing at 13-min intervals. Glucagon (0.5 mg/50 ml saline) was applied before the second examination. The authors investigated the differences of lactate (La) and lactate-pyruvate ratio (La:Py) between arterial blood and coronary sinus (a-cs diff) and the values of serum transaminases and glycaemia. A negative La and/or La:Py a-cs diff during or after pacing was interpreted as a positive qualitative sign of induced acute myocardial ischaemia. Application of glucagon on the second cardiac pacing led to worsening of the metabolic situation in 71% of patients; none of the patients showed improvement. The La:Py a-cs diff after glucagon was negative in all patients.