IEEE transactions on bio-medical engineering
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IEEE Trans Biomed Eng · Aug 1991
Applications of adaptive filtering to ECG analysis: noise cancellation and arrhythmia detection.
Several adaptive filter structures are proposed for noise cancellation and arrhythmia detection. The adaptive filter essentially minimizes the mean-squared error between a primary input, which is the noisy ECG, and a reference input, which is either noise that is correlated in some way with the noise in the primary input or a signal that is correlated only with ECG in the primary input. ⋯ The primary input of the filter is the ECG signal to be analyzed, while the reference input is an impulse train coincident with the QRS complexes. This method is applied to several arrhythmia detection problems: detection of P-waves, premature ventricular complexes, and recognition of conduction block, atrial fibrillation, and paced rhythm.
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We have studied muscle recruitment with Teflon-insulated, 25 microns diameter, Pt-Ir intrafasicular electrodes implanted in nerves innervating the gastrocnemius and soleus muscles of cats. The purpose of this study was to measure the performance of these bipolar electrodes, which had been designed to optimize their ability to record unit activity from peripheral nerves, as stimulating electrodes. Recruitment curves identified the optimal stimulus configuration as a biphasic rectangular pulse, with an interphase separation of about 500 microseconds and a duration of about 50 microseconds. ⋯ Current and charge densities needed for stimulation were well below levels believed to be safe for the tissue and electrode materials involved. When the spinal reflex pathway was interrupted by crushing the nerve, the force produced by a given stimulus changed in some cases, but not in others, implying that the spinal reflex contribution was not the same in all the implants. We conclude that intrafascicular recording electrodes are also a potentially valuable technology for functional neuromuscular stimulation, and warrant further development.