Takotsubo cardiomyopathy, a condition more commonly known as broken-heart syndrome, could be caused by an impairment in the parasympathetic nervous system, according to researchers from the New York Universty School of Medicine. "We thought if the sympathetic [system] isn't the whole story, maybe there is a problem with the parasympathetic," lead researcher Dr. Harmony Reynolds told The Wall Street Journal.

The findings were derived from a study involving 10 women who had a confirmed history of broken-heart syndrome and 10 healthy women who served as controls. The researchers administered various tests to bring about physical and mental stress on the study participants. The women's blood pressure was monitored during the study. Brachial artery flow-mediated vasodilation was also obtained.

Previous studies pointed to the sympathetic nervous system as the root of takotsubo cardiomyopathy. The sympathetic nervous system is responsible for the body's "fight or flight response" - its response to a perceived attack or a harmful situation.

However, the present study suggested that an impairment in the parasympathetic nervous system, which is responsible for slowing the heart rate and calming the body down, could be the cause of broken-heart syndrome. "Even long after the initial episode, women with previous episode of TC have excessive sympathetic responsiveness and reduced parasympathetic modulation of heart rate," the researchers wrote. "Impaired baroreflex control may therefore play a role in TC."

Other cardiologists gave positive comments on the research findings. Dr. Gregg Fonarow from the David Geffen School of Medicine at UCLA said the study provided "another piece of the puzzle." He added that the discovery could give a "potential explanation for the underlying cause [of takotsubo] and will help foster additional research," according to The Wall Street Journal.

Broken-heart syndrome can be triggered by strong emotions like grief and anxiety and is often experienced by post-menopausal women. It has symptoms similar to those of a heart attack - chest pain, arm pain, shortness of breath - and can be misdiagnosed initially as one, according to WebMD.

The study was published online Nov. 5 in the American Journal of Cardiology.