CD&D National Editor

A "better mousetrap" is always the metaphorical gold standard sought by technology developers. And a group of researchers focused on signal extraction and separation believe they are on track to develop a better fetal heart monitor.

Another metaphor here could be that of the village – in this case, the global village, since the developers of the new system come from several countries and a range of disciplines and interests.

There is, of course, no lack of fetal monitoring technology. The Internet provides access to and listings of a whole range of such devices, providing a variety of assessments for both baby and mother.

But Gari Clifford, PhD, a researcher at the Harvard-Massachusetts Institute of Technology Division of Health Sciences (Boston), told Cardiovascular Devices & Drugs that the new fetal monitoring system he and his colleagues are developing opens a new window both into earlier monitoring of the fetal heartbeat, and for new research opportunities in this arena to foresee any problems that a fetus may be having in order to deal with these potential problems earlier.

Key to the new system, he said, is a combination of "advanced hardware" and new algorithms that do a better job of separating the background "noise" and the mother's heartbeat from the signals from the developing fetal heart and doing this non-invasively.

Like some other fetal monitoring systems, the new method employs a Holter monitor-type belt that the woman wears around her waist. The prototype belt incorporates 32 electrodes, and the information picked up from the fetus provides what Clifford describes as a varied picture of the activity of the fetal heart.

Clifford compares the multidimensional view of the fetal heart to a hologram because its electrical activity is recorded from many different angles rather than the single, simplistic measurement of heartbeat provide by other monitors.

This information, he says, might ultimately be gathered in the final device via fewer electrodes, perhaps only nine.

He contrasts this approach to other fetal monitoring systems, all of which he described as significantly inferior.

Ultrasound, he notes, is a non-invasive modality that can be used fairly early but offering only a crude assessment of fetal heart pulsation, he says.

The other common type of fetal monitor is used in the labor and delivery process but is significantly invasive, requiring attachment of an electrode to the head, or scalp, of the fetus.

Besides using the sticky "patch" electrodes used in Holter monitors, the new device also is also equipped "dry" electrodes to allow quick on-and-off use when necessary, or longer use, to avoid skin irritation.

Monitoring the fetal heartbeat at the mother's abdomen using traditional ECG signals is non-invasive but weak, Clifford notes, because compromised by surrounding noises and the mother's heartbeat which is always the most dominant. And he says that the normal process of separating the three signals – background noise, mother's heartbeat, fetal heartbeat – tends to distort the characteristics of the fetal heartbeat and thus miss potential clinical problems.

Clifford says that like many diagnostic systems, the monitor is likely to be used first for what are considered "at-risk" pregnancies but then be deployed more generally.

Importantly, he says that the new algorithm/hardware monitoring combination being developed might be used very much earlier in the pregnancy than any of the other devices – potentially as early as the 20-week trimester period. This could then be instrumental in spotting developmental problems at the earliest stage, be so sensitive to the fetal heart rhythms that it could rule out the need for Cesarean birth more accurately – saving significant dollars and co-morbidities — and ultimately spot a variety of other problems besides heart irregularities.

The new hardware/algorithm combination does this separation in a way that enables detection of the smallest problems in fetal heart rhythm, he says.

Based on work in signal processing and source separation, the system design breaks any signal into its source components. The researchers have described their approach in papers published in the IEEE Transactions on Biomedical Engineering and the EURASIP Journal on Advances in Signal Processing.

While only a minority of pregnancies suffer from such fluctuations, the researchers note, they say that these problems may be extremely critical nevertheless because the problems that do exist can result in seriously negative outcomes, such as certain infections and a loss of oxygen to the baby if it is strangled by the umbilical cord.

Clifford said that that the system might even be able to offer new research opportunities for understanding the possible underlying, prenatal sources of sudden infant death syndrome.

"Our objective is to make a monitoring system that is simultaneously cheaper and more effective" than what is currently available, said Clifford. He said that the research team is currently comparing the use of the new monitoring system against traditional monitoring methods in about 150 patients to validate it.

Clifford has an impressive list of credentials, including being principle research scientist in the Laboratory for Computational Physiology at the Harvard-MIT Division of Health Sciences and engineering manager of an NIH-funded research program titled "Integrating Data, Model, and Reasoning in Critical Care." He is the one most often interviewed about the new monitoring system, but he told CD&D he was anxious to note the collaborative efforts of many others in the development of the monitor.

He said his primary colleagues on the signal-processing work include Reza Sameni – who developed much of the signal separation method in his PhD work – along with Professor Christian Jutten of Institut National Polytechnique de Grenoble (Grenoble, France), and Professor Mohammad Shamsollahi of Sharif University of Technology in Tehran.

Clifford's key collaborator on the clinical side is Adam Wolfberg, MD, an obstetrician and instructor at the Tufts University School of Medicine (Boston). And he and Tufts turned to E-TROLZ (North Andover, Massachusetts) for system construction and algorithm validation.

The original development of the device was funded by the Center for Integration of Medicine and Innovative Technology (CIMIT; Boston), and several patent applications on the work have been licensed by MindChild Medical (Boston).

Clifford said he expects that the system could be commercially available in two to three years, following FDA approval.