Author :
Ng, J. ; Sahakian, AV ; Swiryn, S.
Author_Institution :
Northwestern Univ., Evanston, IL, USA
Abstract :
Changes in body position are known to change the electrical axis of the heart, resulting in changes in the QRS amplitude, ST segment shifts and T-wave inversions. We investigated the effect of body position changes on the frontal-plane P-wave axes of 10 healthy volunteers. The subjects were monitored using three accelerometers recorded with two ECG channels. The 10 subjects followed a protocol of standing, sitting, walking, lying supine and lying on their right and left sides for five minutes each. Median P-wave and QRS vectors in the frontal plane were computed. With standing, sitting, right and left positions, the P-axis had mean shifts of 10±11 deg, 7±12 deg, 2±11 deg and 12±6 deg, respectively, when compared to the supine position. When compared to QRS shifts, P-wave shifts were larger, with more variability, and were poorly correlated with QRS axis shifts
Keywords :
acceleration measurement; angular measurement; biomechanics; biomedical measurement; electrocardiography; patient monitoring; ECG channels; P-wave shifts; QRS amplitude; QRS axis shifts; ST segment shifts; T-wave inversions; accelerometers; body position changes; frontal-plane P-wave axis; heart electrical axis; lying; median P-wave vector; median QRS vector; sitting; standing; supine position; variability; walking; Accelerometers; Electrocardiography; Electrodes; Heart; Legged locomotion; Lungs; Monitoring; Protocols; Thigh; Voltage;
