Effects on QRS-waveforms and ST-T-segment by changes in body position during continuous 12-lead ECG: a preliminary report

ST-segment monitoring by Holter or by continuous 12-lead ECG-monitoring have prognostic value in unstable angina and myocardial infarction. However, "pseudo-changes" due to changes in body position may cause problems during monitoring for indicators of silent ischemia. Therefore, ischemia-monitoring with continuous 12-lead ECG was performed in 36 clinically stable patients in different body positions. Using the ECG in supine position as reference, ST-segment changes were usually small but reached significant levels in some patients, especially in the left lateral decubital position. However these deviations of the ST-segment seemed to arise under certain circumstances, which are possible to recognize in the clinical setting.