A collaboration between Queen's scientists and researchers at Johns Hopkins University has led to a significant discovery about the cause of sudden heart failure after open-heart surgery, a common occurrence that results in most heart patients having to spend a full day in intensive care following surgery and costing taxpayers millions of dollars every year in post-operative medical care.
The work of Queen's researchers Dr. Jennifer Van Eyk, an assistant professor with the Dept. of Physiology, and Queen's graduate student Jason McDonough, in collaboration with Drs. Anne Murphy, David Kass and Eduardo Marban at John Hopkins, focuses on molecules linked to heart muscle contractions and contributes to a new understanding of how a problem at the molecular level can lead to a type of acquired heart failure.
Published last week in the journal Science, the study shows how a protein called troponin I that is a key part of a heart muscle cell's contracting "machinery" is damaged and how that leads to heart failure known as "cardiac stunning".
Last month, the research was picked by the American Heart Association for its list of top 10 research advances in heart disease and stroke in 1999.
"We are very excited about the role we have played in this study," says Dr. Van Eyk. "This points to new ways of preventing and treating this specific heart problem and also enhances our understanding of the more common type of chronic heart failure."
When blood flow to the heart is reduced or stopped, problems develop with the regulated contraction of the heart muscle which may persist even after flow has been re-established. The researchers at Queen's and Hopkins had independently demonstrated that a specific protein key to contraction of the heart is "clipped" (a small piece chopped off the end) even in mild cases of blood flow interruption. At Queen's, the Van Eyk laboratory went on to identify of the exact clip. This lead to the collaboration with the group from Johns Hopkins. In order determine that the faulty protein is sufficient to causes cardiac stunning, the researcher inserted the abnormal troponin I in into otherwise healthy mice and documented the development of reduced or stopped blood flow.
Simultaneously, the Queen's researchers were determining that these findings are applicable to humans. "Our laboratory was able to demonstrate that the protein is clipped in the heart muscle of patients having bypass surgery. This was achieved by analyzing small pieces of heart muscle obtained before and after coronary bypass surgery, thanks to samples provided by Dr. Glorianne Ropchan, cardio-thoracic surgeon at Kingston General Hospital," explains McDonough.
"Now that we know what is causing cardiac stunning, we might be able to decrease the amount of injury that occurs during bypass surgery and other relatively mild cardiac events. This opens up the possibility of new therapeutic approaches," says Dr. Van Eyk.
The Queen's research was funded by grants from the Heart and Stroke Foundation of Canada, Medical Research Council of Canada and National Institutes of Health.
Note: The original news release can be found here.
Materials provided by Queen's University. Note: Content may be edited for style and length.
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