Session P72.4

Non-Contact Measurement of Cardiac Electromagnetic Field in Mice Using an Ultra-Small Atomic Magnetometer: A Feasibility Study

B Lindseth, P Schwindt, J Kitching, D Fischer, V Shusterman*

University of Pittsburgh
Pittsburgh, PA, USA

The development of clinical applications of magnetocardiography has been impeded, at least in part, by the large size of the magnetic-field measurement systems.
We present the first measurements of the cardiac electromagnetic field with an ultra-small (2mm), atomic magnetometer constructed with microfabrication techniques.
Measurements were performed in two wild-type mice sedated and placed into a two-layer magnetic shield. Electrocardiogram (ECG) was measured using subcutaneous, non-magnetic electrodes placed in the standard, limb position. The magnetometer was placed approximately 2 mm away from the surface of the skin in the sternal region. The ECG and the magnetometer (MCG) signals were fed into a multiplexer system and recorded simultaneously at 1kHz/channel for post-processing. To control for mechanical artifacts, consecutive recordings were performed, as follows: 1) with the animal above/below/far away from the sensor, and 2) with ECG electrodes connected/disconnected from the animal. The ECG and MCG signals were averaged using the ECG R-peaks as the fiducial points.
QRS complexes were identifiable in the MCG signals in all recordings except for those performed when the animal was moved far away from the sensor (>10 cm). The QRS complexes became identifiable with the averaging of >20 cardiac cycles. There was a time lag (~10 ms) between the QRS in the ECG and MCG signals and some loss of the high-frequency components in the MCG signal due to the suboptimal sampling of the real-time MCG filter.
Non-contact recording of cardiac electromagnetic fields with a microfabricated magnetometer is feasible in a shielded environment. Further refinements in signal processing should improve the quality of MCG recordings and might allow recordings in unshielded environment.

(Abstract Control Number: 195)