Mayo Clinic study could lead to more effective treatment for heart failure

Tuesday, February 20, 2007

SCOTTSDALE, Ariz. - New research by Mayo Clinic appears to defy conventional understanding of the intricate functioning of the human heart and could lead to new advances in the treatment of heart failure.

"The newest discovery is that the heart's electricity and muscle activity intimately entwine to produce an intense swirl in the moving blood," explains Bijoy Khandheria, M.D., chair of the Division of Cardiology at Mayo Clinic in Arizona. "The efficiency of this blood movement is enhanced by a current created by the synchronized movement of the heart muscle," he adds.

The research is significant enough in terms of its potential that the findings are chronicled in the cover story in the Feb. 27 edition of Journal of the American College of Cardiology and are described in a lead editorial as having "significant implications" in terms of describing cardiac physiology and pathology.

The studies clarify the "interaction among left ventricle anatomy, electric activation and intracavitary flow," the authors of the editorial note. "These findings, coupled with advances in noninvasive cardiac imaging technology, offer the potential to use cardiac contraction pattern and intracavitary flow as new descriptors of cardiac physiology and pathology."

Sophisticated digital imaging techniques were used to observe the movement of the heart muscle. According to Marek Belohlavek, M.D., Ph.D., also from Mayo Clinic, senior author of the study, the key to understanding the heart's action is to study it at a high-temporal resolution.

The findings are in contrast to previous thinking that the heart is a pump, pumping blood from the left ventricle cavity into the body while the heart fills with new blood during a relaxation phase. Instead, the "intense swirling during the early phase of heart's contraction" described by Khandheria and his research team provides a new understanding to "heart's vortex motion," a fluid force that determines how strong the heart is in any given individual. More precise and sophisticated imaging techniques can lead to better planning for heart surgeries to correct malfunctioning or failing hearts and other cardiac problems, Khandheria said.

"In this study, we injected tiny gas bubbles into blood flowing inside a heart and then monitored the movement of the gas bubbles with sound waves. The technique was used to understand the finer details of blood-flow sequence inside the chambers of the heart," says Belohlavek.

Using a method called digital particle imaging velocimetry, "We tracked the tiny bubbles within the heart and computed more than 200 flow velocity measurements every second," says Partho Sengupta, M.D., lead author and designer of this study. "This provided detailed trajectories of blood flow inside the chambers of the heart. We observed swirling blood flow currents during each heart beat, particularly during phases when the blood flow was previously thought to move only a very little or not at all."

The physician researchers are hopeful that this greater understanding of the force with which the heart works, "physicians can better fit expensive treatment strategies, such as pacemakers, to the appropriate patients," notes Khandheria.

Currently heart failure is a condition that affects nearly 5 million Americans.

Other researchers participating in the study include Shiro Yoshifuku, M.D.; Josef Korinek, M.D. and Arshad Jahangir, M.D., all from Mayo Clinic.

Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. As a leading academic medical center in the Southwest, Mayo Clinic focuses on providing specialty and surgical care in more than 65 disciplines at its outpatient facility in north Scottsdale and at Mayo Clinic Hospital. The 208-licensed bed hospital is located at 56th Street and Mayo Boulevard (north of Bell Road) in northeast Phoenix, and provides inpatient care to support the medical and surgical specialties of the clinic, which is located at 134th Street and Shea Boulevard in Scottsdale.

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