New imaging techniques pinpoint heart structure and function

Wednesday, November 08, 2006

SCOTTSDALE, Ariz. - An important first step in using new approaches to treating patients with heart failure - a condition that affects nearly 5 million Americans - requires scientific understanding of the relationship between the form of the heart and function, according to Bijoy K. Khandheria, M.D., FASE, FESC, FACC, chair of the Division of Cardiology at Mayo Clinic in Arizona.

To that end, Mayo Clinic researchers, through the use of new, high-resolution imaging methodology, have discovered an important link between the structure - and the function - of a beating heart. The advanced imaging allows researchers to observe the unique geometry of the left ventricle of the heart and can more precisely provide data for calculating heart strain and other cardiac impairment.

"Current biological models for understanding heart failure are insufficient for explaining both how the beating heart functions and the benefits of several new, emerging therapies," explains Dr. Khandheria, senior author of the study. He adds that conventional imaging methods do not allow for complex study of the three-dimensional pattern of ventricular activation and contraction.

The new, evolved imaging can lead to better planning for heart surgeries to correct malfunctioning or failing hearts and other cardiac therapies, Dr. Khandheria notes.

Importantly, understanding the cardiac structure-function relationship will also be essential in helping construct "true anatomical" models to help guide the emerging field of cardiac tissue engineering. Cardiac tissue engineering encompasses the production of bio-artificial tissue that can mimic the structure of healthy hearts and can be integral to designing "future components of a bio-artificial heart," adds Dr. Khandheria.

The findings will be published in the November issue of the Journal of the American College of Cardiology. The study expands on a concept previously pioneered by Marek Belohlavek, M.D. Ph.D., also of Mayo Clinic in Arizona. The study is entitled Left Ventricular Structure and Function: Basic Science for Cardiac Imaging.

Earlier published information by Dr. Khandheria and colleagues reported a redefinition of how the human heart functions - a discovery that can also lead to treatment of heart failure. The researchers note that the heart is not simply a "pump," pumping blood from the left ventricular cavity into the body while the heart fills with new blood during a relaxation phase. Instead, their research now demonstrates that the blood flow within the heart forms a vortex and, it is the strength of the vortex that determines how strong the heart is in any given individual. Fine tuning of the electrical and mechanical activity of the heart results in formation of vortex within the cavity of the heart. It is almost like a "tornado" within the heart, which results in a "wringing" motion, causing the heart to eject blood for distribution to the various parts of the body.

Further study of the construct of the heart and how the left ventricular cavity functions could lead to a means of preventing impairment of the heart that leads to heart failure, according to Dr. Khandheria.

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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