Mini 'stress tests' could help condition heart to survive ma...( CINCINNATIPeople who experience brie...),Health

CINCINNATIPeople who experience brief periods of blocked blood flow may be better conditioned to survive a full-blown heart attack later, according to new research from the University of Cincinnati (UC).

In a five-year laboratory study, UC surgeon-scientist Karyn Butler, MD, found that when the heart experiences short periods of stress, either from reduced blood flow or high blood pressure, it activates a protective molecular pathwayknown as JAK-STATthat protects the heart muscle. The pathway, which is normally dormant in the heart, was originally identified in disease-fighting white blood cells as a mediator of infection and has recently been targeted for its role in heart health.

Butler says when the JAK-STAT pathway is active and functioning, it can help precondition and protect the heart from damage caused when blood flow is restored after a period of decreased flow, as occurs after a heart attack.

These mini stress tests appear to push the heart muscle into an adaptive state where it gets used to how long-term stress feels, Butler explains. This preconditioning helps the heart muscle better tolerate longer episodes of compromised blood flow.

Her team reports their findings in the January 2008 issue of the American Journal of Physiology: Heart and Circulatory Physiology.

A trauma/critical care surgeon at University Hospital in Cincinnati, Butler wanted to determine how she could help patients with heart disease from high blood pressure tolerate cardiac ischemia, which occurs when vessels become narrowed or blocked and results in a dangerous reduction of blood flow to the heart.

To study the hearts response to restored blood flow after cardiac ischemia and in the presence of hypertension, Butler developed a hypertrophied (enlarged) animal heart model to mimic the conditions of heart enlargement and congestive heart failure in humans.

The enlarged heart model was then subjected to precondit
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