Laser vibrometry checks heartbeat

07 Dec 2005

Italian scientists demonstrate a non-contact technique for analyzing heartbeats.

An optical technique that provides accurate, non-contact monitoring of the heart is being trialled in Italy with very promising results. Based on Laser Doppler Vibrometry (LDV), the approach offers several advantages over electrocardiograpy, the conventional analysis scheme.

No patches

Rather than collecting electrical signals from the heart the optical scheme called VibroCardioGraphy (VCG) uses a light beam to measure the velocity and displacement of the chest wall. It is the brainchild of Enrico Tomasini’s LDV research group at Universita Politecnica delle Marche in Ancona.

Extra info

“We have proved that we can obtain the information for medical doctors as good as that provided by an ECG [electrocardiogram],” said Lorenzo Scalise, a member of Tomasini’s group. “But we can also derive extra information related to the mechanical function of the heart and patient’s breath frequency.”

good agreement

However, the most important benefit of the new technique is the ability to make measurements without the need to apply electrical patches to the skin. The VCG scheme simply illuminates the patient’s chest with a low-power red laser beam and analyzes the reflection.

As a result it is ideal for use with burn victims, new born babies in incubators or other situations where it is hard or unwise to apply patches. What’s more it overcomes concerns about electromagnetic interference upsetting ECGs or inaccurate readings if the patches are poorly located.

“In our tests, the laser head was placed about 1.5 m from the patient’s chest wall and a He:Ne source performs a velocity measurement with a resolution of up to 0.5 µm per second,” said Scalise. “The laser power is less than 1 mW so no special safety measures are required.”

To date, Scalise and his colleagues Umberto Morbiducci, Mirko De Melis and Mauro Grigioni have tested more than 20 patients including some wearing pace makers. They are now talking to companies that are interested in commercializing the idea.

Author

Oliver Graydon is editor of Optics.org and Opto & Laser Europe magazine.