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CUE 2004

MECHANICAL ENGINEERING
"Electronic Ear" Detects and Characterizes Heart Murmurs

A nurse at The Children's Hospital in Denver records an infant's heartbeat with an electronic stethoscope. The recording is fed into the "Electronic Ear," which interprets the sound and distinguishes innocent from serious heart murmurs.

The detection of a heart murmur in an infant or young child is likely to send a parent's blood pressure soaring. Not knowing whether it is a sign of something serious or not, they typically worry throughout the long wait to see a specialist.

Nine out of 10 infants and young children experience heart murmurs, but it is a cause for worry in only a small fraction of those cases. The prevalence of serious heart disease in children is less than 1 percent.

These figures provide clear evidence that primary care providers must have effective screening mechanisms in place to differentiate between innocent and pathological murmurs in lieu of referring all patients with heart murmurs to specialists. At the same time, the primary care provider must have complete confidence that what is called an innocent murmur does not stem from any form of congenital or acquired heart disease in a patient.

To solve this problem, a team of researchers led by Professor Roop Mahajan of Mechanical Engineering and Dr. Curt DeGroff of The Children's Hospital has developed the "Electronic Ear," a low-power, hand-held device that records and interprets heart sounds, distinguishing innocent from serious heart murmurs. Through a connection to a digital stethoscope, the Electronic Ear records heart sounds, including those beyond the frequency range of the human ear. These sound feeds are processed using digital signal process analysis and fed into a custom artificial neural network for classification by implicit discriminant boundaries.

Initial results have been very encouraging and indicate the great promise of the Electronic Ear as an accurate, portable, and low-cost screening device. The device also can be designed to distinguish different types of malignant murmurs, predicting anatomical heart defects or other diseases. The early detection of malignant murmurs and the following intervention by cardiologists has the potential to save lives and prevent severe health problems that may arise if the underlying problem is left untreated.

The Electronic Ear also offers a practical screening approach for developing nations. Cardiovascular disease accounts for a third of global deaths, 78 percent of which occur in low- and middle-income countries, and it is predicted to be the leading cause of deaths in developing nations by 2010. Mahajan is seeking funding to further develop, validate, and transfer the Electronic Ear and other health and disease screening tools to developing countries lacking sufficient healthcare infrastructure.

Other screening tools under development at CU include portable biosensors called health logs, which could be worn by patients to collect and interpret physiologic measurements from individuals suffering from, or at risk of developing, infectious diseases; and rapid, inexpensive, high-throughput DNA testing that employs a lab-on-a-chip design and could provide DNA testing in developing nations where molecular genetic laboratory resources and expertise are absent.

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