Detection of body position changes and its effect on ST-changes in the continuous 12-lead electrocardiogram

It is well known that changes in the body position (BPC) can have marked changes on the electrical axis of the heart. This may cause ST-segment shifts and/or T-wave inversions, triggering false alarms during continuous ECG monitoring. To investigate the effects in the CCU setting, a body position test (BPT) has been set up to measure the effect during controlled BPC. The ECG obtained in the supine position was used as reference. A scalar and spatial approaches were used. The scalar approach uses linear regression analysis, the supine position being the reference mapping all measurements to the supine position. The spatial approach uses the derived VCG by applying the inverse Dower transformation. This paper describes the results of the first 54 patients done so far. Marked ST-changes (>100 muV) were observed in II patients out of the 54 when turning to their left side. Other positions appear to have much less effect. A concomitant axis shift in the frontal plane of more than 15 degrees was present in 5 of these 11 patients with ST-changes. Two patients showed T-wave inversion when turning from supine to the left side.