Abstract: An apparatus and method is provided for improving the quality of electrocardiogram (ECG) signals obtained from a patient undergoing magnetic resonance imaging (MRI) wherein the ECG signal has relatively high levels of noise or interference voltages induced on it by changing magnetic fields. The apparatus includes the arrangement of a differential amplifier, a prefilter, a signal limiter (SL) circuit and an intermediate amplifier with an integral low pas filter. The prefilter limits the rise time or high frequency component of the noise or interfering voltages induced on the ECG that are presented to the signal limiter.

Abstract: A lead set assembly is capable of coupling electrodes to a separate device. The assembly includes two leads. The condition sense lead features two conductive paths, each being connectible to one electrode for conveying a bioelectric signal therefrom and capable of having a first noise signal induced therein by electromagnetic emanations. The noise pickup lead also features two conductive paths, each being effectively topographically aligned with one conductive path of the condition sense lead to form a noise-matched pair therewith and capable of having a second noise signal induced therein by the electromagnetic emanations. In each noise-matched pair, this enables the second noise signal to be substantially approximate to the first noise signal. The lead set assembly can thus be used to convey to the separate device (I) the bioelectric and first noise signals using the condition sense lead and (II) the second noise signals using the noise pickup lead.