Kevin S. Honeyager

Adaptive reduction of motion artifact in the electrocardiogram

The electrocardiogram (ECG) is the body-surface manifestation of the electrical potentials produced by the heart. The ECG is acquired by placing electrodes on the patients skin. Motion artifact is the noise that results from motion of the electrode in relation to the patients skin. Motion artifact can produce large amplitude signals in the ECG that may be misinterpreted by clinicians and automated systems resulting in misdiagnosis, prolonged procedure duration, and delayed or inappropriate treatment decisions. Motion artifact reduction is an unsolved problem because its frequency spectrum overlaps that of the ECG. This paper presents initial results of a novel approach to reducing ECG motion artifact. The hypothesis is that motion artifact can be reduced using electrode motion as the reference signal to an adaptive filter. Electrode motion was measured with two custom-developed sensors that utilized anisotropic magnetoresistive sensors and accelerometers. Motion artifact was induced by manually pushing on the electrode, pushing on the skin around the electrode, and pulling on the lead wire. Using an adaptive filter and the motion signal, the induced motion artifact was reduced in all data sets.

Prototype device for assessing spinal fusion success

A device to non-invasively assess spinal fusion was prototyped and bench tested. The device performs real-time calculations of the separation distance between the vertebrae involved in the fusion, postoperatively. The device is comprised of a passive implantable sensor and external interrogator. Sensor implantation would occur during spinal fusion surgery. During postoperative follow-ups, the physician will use the external interrogator to measure the vertebral separation during motion. The performance of the prototype device was investigated using an experimental bench that simulated vertebral motion parameters. A randomized study of performance factors including sensor displacement, interrogator-sensor separation, and the presence of bovine skeletal muscle was conducted and the results statistically analyzed. The bench testing verified that the displacement of sensor components could discriminate displacements to /spl plusmn/0.5 mm. In addition, the distance between the interrogator and sensor does not affect the device response, indicating that the interrogator position is not critical. The technical concepts behind this prototype have been shown to be effective and feasible.