Researchers in the US claim that exposing a person to a magnetic field could reduce their risk of a heart attack by streamlining the flow of blood around their body. While the work currently remains just a proof-of-principle, the researchers believe that their technique could ultimately provide an alternative to drugs in treating a range of heart conditions.

Heart attacks and stokes can strike for a variety of reasons. But research suggests that all such vascular conditions are linked by one common symptom – high blood viscosity. Drugs such as aspirin are frequently prescribed to help lower blood viscosity, but these can have unwanted side effects often related to irritation of the stomach. Now, an alternative to drugs may be at hand following recent work by Rongjia Tao at Temple University and his colleague Ke Huang at the University of Michigan.

In their experiment, Tao and Huang showed that applying a 1.3 T magnetic pulse to a small sample of blood can significantly reduce it's viscosity. About 8 ml of blood with a viscosity of 7 centipoises (cp) – above healthy limits – was contained at body temperature (37 °C) in a test tube. The tube formed part of a device called a capillary viscometer used to measure viscosities. The sample was then exposed to a magnetic field applied parallel to the direction of flow of blood via a coil around the edge of the test tube. After one minute of exposure to the field, the blood's viscosity had been reduced by 33% to 4.75 cp. With no further exposure to the field, the viscosity had only risen slightly to 5.4 cp after 200 min, which is still within healthy limits.

In a paper accepted for publication in Physical Review E, the researchers describe how the effect is probably caused by the response of red blood cells. These iron-rich cells are the most common type of blood cell and they play the leading role in transporting oxygen around the body. In the presence of a strong magnetic field, the red blood cells form chains that align themselves with the field lines where convoys of red blood cells line up behind a leading cell. This process could enable the cells to pass through the blood in a more streamlined fashion, thus reducing the blood's viscosity.

Towards clinical trials

Tao says that patients can safely be exposed to magnetic fields of up to 3 T. He intends to develop the work further by testing blood flow under a magnetic field in capillary tubes that are similar in size to blood vessels. He also plans to apply for a research grant from the US National Institutes of Health to allow clinical trials to be carried out.

Kalvis Jansons, a mathematician at University College London, believes that the researchers may be onto something "very interesting". "If the effect really does exist, it would appear to me that it would not be difficult to use it in a clinical setting," he says. But he also believes that a lot of work would need to be done to show that the process is safe. "Could it lead to blood clots, for example?" he asks.

Giacinto Scoles, a materials scientist at Princeton University who develops medical applications, believes there is a "tremendous thirst" in the medical community for this kind of physics-based innovation. "I believe the work has raised a lot of interesting questions and that a new field of investigation has been opened up," he says.

But the medical community will still need to be convinced about the need for the new technology and about its safety. Tammy Ustet, a medical doctor who carries out rheumatology research at the University of Chicago, believes that the main focus should remain tackling the causes of vascular conditions. "Treating symptoms is extremely important, but treating the root cause is the best way to relieve symptoms," she says.