[Estimation of myocardial oxygen extraction dynamics in effort angina by continuous measurement of coronary venous saturation].

To estimate myocardial oxygen extraction dynamics in the situation of increased myocardial oxygen requirement, we made a continuous measurement of coronary venous oxygen saturation (CSO2-Sat) using the fiberoptic catheter system and a measurement of myocardial lactate extraction ratio (MLER) in 14 patients. Ten patients showed ischemic ST depression and/or anginal episodes during the pacing loading, while 4 patients did not. Although transient decreases in CSO2-Sat were observed in the non-ischemic 4 patients immediately after the initiation of pacing or with the increase in pacing rate. CSO2-Sat and MLER remained almost unchanged from the start of pacing to the time of maximal pacing. However, in the 10 patients who developed ischemia, CSO2-Sat fell from 39.5 +/- 1.8% before pacing to 32.9 +/- 2.8% at the time of maximal pacing (p less than 0.05), with an average decrease of 6.6 +/- 2.8%. Data of MLER obviously indicated the appearance of myocardial ischemia (32.1 +/- 4.7% to 9.2 +/- 10.3%, p less than 0.05). These findings suggest that myocardial oxygen extraction will increase transiently or continuously to meet the myocardial oxygen demand when increase in coronary blood flow is limited. Continuous measurement of coronary venous saturation may be useful for the early detection of myocardial ischemia.