Correlation of intramyocardial electrocardiograms with polarographic oxygen and contractility in the nonischemic and regionally ischemic left ventricle.

W HAVE previously shown that the enicardial-surface electrocardiogram is an inadequate index of localized myocardial ischemia. While striking chanares of polarographic oxygen and contractility regularly occur a few seconds after coronary arterial branch occlusion, epieardial electrocardiographic changes are delayed and sometimes absent. Intramyocardial electrocardiographic studies, on the other hand, reveal that localized ischemia disturbs myocardial electrical activity at least as early as either oxygenation or contractility, and over a more extensive area. We have developed a technique for amplification and recording of oxygen-reduction currents and electrocardiograms simultaneously from the same lead-point" in the myocardium. This technique was combined with motion-picture records of muscle contraction and epicardial-surface color. Thus, simultaneous information about electrical activity, oxygenation, and contractility in locally altered myocardium and adjacent, undisturbed muscle became available. This makes possible, as we will show in the present paper, an assessment of the limitations of