Magnetocardiography is a technique to measure the magnetic field

Magnetic field

A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

s produced by electrical activity in the heart

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

 using extremely sensitive devices such as the Superconducting Quantum Interference Device (SQUID

SQUID

A SQUID is a very sensitive magnetometer used to measure extremely weak magnetic fields, based on superconducting loops containing Josephson junctions....

s). If the magnetic field is measured using a multichannel device, a map of the magnetic field is obtained over the chest; from such a map, using mathematical algorithm

Algorithm

In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

s that take into account the conductivity structure of the torso

Torso

Trunk or torso is an anatomical term for the central part of the many animal bodies from which extend the neck and limbs. The trunk includes the thorax and abdomen.-Major organs:...

, it is possible to locate the source of the activity. For example, sources of abnormal rhythms or arrhythmia, may be located using MCG.

History

The first MCG measurements were made by Baule and McFee using two large coils placed over the chest, connected in opposition to cancel out the relatively large magnetic background. Heart signals were indeed seen, but were very noisy. The next development was by David Cohen, who used a magnetically-shielded room to reduce the background, and a smaller coil with better electronics; the heart signals were now less noisy, allowing a magnetic map to be made, verifying the magnetic properties and source of the signal. However, the use of an inherently noisy coil detector discouraged widespread interest in the MCG. The turning point came with the development of the sensitive detector called the SQUID (superconducting quantum interference device) by James Zimmerman. The combination of this detector and Cohen's new shielded room at MIT

Massachusetts Institute of Technology

The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

 allowed the MCG signal to be seen as clearly as the conventional electrocardiogram

Electrocardiogram

Electrocardiography is a transthoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body...

, and the publication of this result marked the real beginning of magnetocardiography (as well as Biomagnetism generally).

Magnetocardiography is now used in various laboratories

Laboratory

A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...

 and clinic

Clinic

A clinic is a health care facility that is primarily devoted to the care of outpatients...

s around the world, both for research on the normal human heart, and for clinical diagnosis

Diagnosis

Diagnosis is the identification of the nature and cause of anything. Diagnosis is used in many different disciplines with variations in the use of logics, analytics, and experience to determine the cause and effect relationships...

.

See also

• Biomagnetism
  Biomagnetism
  Biomagnetism is the phenomenon of magnetic fields produced by living organisms; it is a subset of bioelectromagnetism. The study of the biological effects of magnetic fields is magnetobiology...
  
  
• Magnetic field imaging
  Magnetic field imaging
  Magnetic Field Imaging is a non-invasive and side-effect-free cardiac diagnostic method. It detects and records the electromagnetic signals that are associated with the heartbeat using a multi channel magnetic sensor array. The electric signals are known from the ECG and recordings of the magnetic...
  
  
• Magnetoencephalography
  Magnetoencephalography
  Magnetoencephalography is a technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using arrays of SQUIDs...
  
  
• Magnetogastrography
  Magnetogastrography
  Magnetogastrography is the science of recording magnetogastrograms . Magnetogastrograms are recordings of magnetic fields resulting from electrical activity from the stomach and can be considered similar to electrocardiograms. The magnetic fields are typically recorded using SQUIDs.-External links:*...
  
  
• David Cohen (physicist)
  David Cohen (physicist)
  David Cohen is known mostly for his pioneering work in the area of Biomagnetism , where he made many of the first measurements....
  
  
• James Edward Zimmerman
  James Edward Zimmerman
  James Edward Zimmerman was born in Lantry, South Dakota. He was a coinventor of the radio-frequency superconducting quantum interference device and he is credited with coining the term.- Career :...
  
  

External links

• http://www.biomag.hus.fi/mcg.html
• http://www.biomag2006.ca
• http://www.biomag2008.org/
• http://www.heartmath.org/research/science-of-the-heart/head-heart-interactions.html