Pulse-Driven Magnetoimpedance Sensor Detection of Cardiac Magnetic Activity

This study sought to establish a convenient method for detecting biomagnetic activity in the heart. Electrical activity of the heart simultaneously induces a magnetic field. Detection of this magnetic activity will enable non-contact, noninvasive evaluation to be made. We improved the sensitivity of a pulse-driven magnetoimpedance (PMI) sensor, which is used as an electric compass in mobile phones and as a motion sensor of the operation handle in computer games, toward a pico-Tesla (pT) level, and measured magnetic fields on the surface of the thoracic wall in humans. The changes in magnetic field detected by this sensor synchronized with the electric activity of the electrocardiogram (ECG). The shape of the magnetic wave was largely altered by shifting the sensor position within 20 mm in parallel and/or perpendicular to the thoracic wall. The magnetic activity was maximal in the 4th intercostals near the center of the sterna. Furthermore, averaging the magnetic activity at 15 mm in the distance between the thoracic wall and the sensor demonstrated magnetic waves mimicking the P wave and QRS complex. The present study shows the application of PMI sensor in detecting cardiac magnetic activity in several healthy subjects, and suggests future applications of this technology in medicine and biology.

[1]  J. C. Norman,et al.  Magnetocardiography of Direct Currents: S-T Segment and Baseline Shifts during Experimental Myocardial Infarction , 1971, Science.

[2]  Shinsuke Nakayama,et al.  Biomagnetic field detection using very high sensitivity magnetoimpedance sensors for medical applications , 2009 .

[3]  S. Yamanaka,et al.  Cell line-dependent differentiation of induced pluripotent stem cells into cardiomyocytes in mice. , 2010, Cardiovascular research.

[4]  A. Arrott,et al.  Angular dependence of magnetization in recording media , 1994 .

[5]  Jagmeet P. Singh,et al.  Catheter ablation of atrial fibrillation the search for substrate-driven end points. , 2010, Journal of the American College of Cardiology.

[6]  Y. Honkura,et al.  Off-diagonal impedance in amorphous wires and its application to linear magnetic sensors , 2004, IEEE Transactions on Magnetics.

[7]  J. Strasburger,et al.  Overview of fetal arrhythmias , 2008, Current opinion in pediatrics.

[8]  A. Nakao,et al.  Characterization of in vitro gutlike organ formed from mouse embryonic stem cells. , 2004, American journal of physiology. Cell physiology.

[9]  Y. Nakaya,et al.  Visualization of cardiac dipole using a current density map: detection of cardiac current undetectable by electrocardiography using magnetocardiography. , 2007, The journal of medical investigation : JMI.

[10]  Hans Koch,et al.  Recent advances in magnetocardiography. , 2004, Journal of electrocardiology.

[11]  Andre Terzic,et al.  Induced pluripotent stem cells: developmental biology to regenerative medicine , 2010, Nature Reviews Cardiology.

[12]  T K Hames,et al.  Pulmonary perfusion and ventricular ejection imaging by frequency domain filtering of EIT images , 1992 .

[13]  K. Mohri,et al.  Amorphous Wire and CMOS IC Based Magneto-Impedance Sensors—Origin, Topics, and Future , 2007 .

[14]  Lior Gepstein,et al.  Modelling the long QT syndrome with induced pluripotent stem cells , 2011, Nature.

[15]  Sébastien Saez,et al.  Optimization of the magnetic noise and sensitivity of giant magnetoimpedance sensors , 2008 .

[16]  R. Fenici,et al.  Clinical application of magnetocardiography , 2005, Expert review of molecular diagnostics.

[17]  H. Izawa,et al.  Intracoronary electrocardiogram recording with a bare-wire system: perioperative ST-segment elevation in the intracoronary electrocardiogram is associated with myocardial injury after elective coronary stent implantation. , 2009, JACC. Cardiovascular interventions.

[18]  S. Nakayama,et al.  Recent advances in studies of spontaneous activity in smooth muscle: ubiquitous pacemaker cells. , 2010, Progress in biophysics and molecular biology.

[19]  Pulse-driven magnetoimpedance sensor detection of biomagnetic fields in musculatures with spontaneous electric activity. , 2011, Biosensors & bioelectronics.

[20]  H. Kuniyasu,et al.  In Vitro Formation of Enteric Neural Network Structure in a Gut‐Like Organ Differentiated from Mouse Embryonic Stem Cells , 2006, Stem cells.