Human intramyocardial oxygen detected through chronic polarographic electrodes

The intramyocardial PO2 was studied in 7 patients after cardiac surgery, by means of a long-term electrode implanted subepicardically in the free wall of the left or the right ventricle, utilizing the polarographic method. Inhalation of 100% O2 or 5% CO2 +95% O2 provoked maximal increases in the myocardial PO2. In most cases intense exercise, and the Valsalva manoeuvre caused a decrease in the PO2. Intravenous propranolol slightly increased the PO2 in one case. Other drugs used in coronary patients caused inconstant effects. Sleeping decreased the heart PO2 in one case. This technique appears to be a useful tool for studying the human intramyocardial PO2 during a period of several weeks.