Many aspects of medicine today involve the science of physics. One of the newest physical methods to be explored, as yet clinically untried, but with promise, has been loosely termed "magnetocardiography." As physicist and cardiologist we have collaborated using this new technique to explore "currents of injury" in myocardial ischemia.
Any flow of electrical current produces a magnetic field, and the same currents from the heart and brain that produce the electrocardiogram and electroencephalogram must also produce a magnetic field outside the body. The heart's magnetic field is extraordinarily weak (about one-millionth of the earth's magnetic field), but it can and has been measured in a highly shielded chamber which excludes magnetic disturbances. Such a chamber of advanced design has been constructed at the Massachusetts Institute of Technology into which was installed a new type of magnetometer of unusually high sensitivity.
We felt that if external magnetic detection of internal