Mysterious ways of the heart

New understanding may lead to earlier diagnoses

Despite its seemingly methodical "thump, thump, thump," the heart's rhythm is as complex as a potential lover's intentions on Valentine's Day.

New research, to be reported in the American Physical Society's peer-reviewed journal Physical Review Letters, seems to show that variety may not only add vitality to a budding romance, but the heart as well. Further, the scientists say they have developed a simple computer algorithm that can help decipher the heart's complexity and use it to distinguish between diseased and healthy hearts.

Under normal conditions, timing between heartbeats changes instant to instant in a seemingly random way. Actually, though, scientists are finding those beats have patterns within patterns - some lasting thousands of beats. Yes, the heart has a memory - as long as it's not broken.

"We have found that heart rate changes have a complicated clustering pattern in healthy people, but that pattern tends to break down - sometimes actually becoming too regular - in people with heart failure," says lead author physicist Yosef Ashkenazy, Ph.D. of Boston University.

"These measurements can be easily taken from clinical data," adds co-author Plamen Ivanov, Ph.D. also at Boston University. "This suggests the possibility of aiding bedside diagnosis and prognosis."

In fact, according to Ashkenazy, one of the simplest measurements may provide the most promise for improving diagnosis. Just recording when the heart rate dances up and down between each beat, is enough information to plug into their algorithm.

The scientists are actually reading between the beats. "A typical EKG records how things change over time using average values. Instant to instant changes are blurred out," says cardiologist Ary L. Goldberger, M.D. of Beth Israel Deaconess Medical Center/Harvard Medical School. "Our study takes advantage of recent explorations into finding hidden information from the beat-to-beat dynamics."

The study involved 18 healthy people and 12 with congestive heart failure, looking at about 30,000 successive heartbeats for each of the 30 subjects. Their method showed a stark contrast between the two groups. The data came from the National Institutes of Health's new Research Resource for Complex Physiological Signals database (www.physionet.org). The researchers, who are now looking at larger databases, say they will also post details of their code for other scientists to use at that web site.

In any event, it seems clear that if your Valentine makes your heart dance a bit, it may be more than romantic. It might actually be healthy.

Contact information for authors of paper:

Yosef Ashkenazy, Ph.D.: tel. 617-353-3891, e-mail: ashkenaz@argento.bu.edu

Ary L. Goldberger, M.D.: tel. 617-667-2517, e-mail: agoldber@caregroup.harvard.edu

Plamen Ivanov, Ph.D.: tel. 617-353-4733, e-mail: plamen@argento.bu.edu

H. Eugene Stanley, Ph.D.: tel. 617-353-2617, e-mail: hes@argento.bu.edu