Researchers at Johns Hopkins have evidence to explain why the supposedly natural act of aging is by itself a very potent risk factor for life-threatening heart failure.
In a study to be presented Nov. 4 at the American Heart Associationís (AHA) annual Scientific Sessions in Orlando, Fla., the Hopkins team analyzed more than a half-dozen measurements of heart structure and pumping function to assess minute changes in the hearts of 5,004 men and women, age 45 to 84, of different ethnic backgrounds and with no existing symptoms of heart disease.
Researchers found that each year as people age, the time it takes for their heart muscles to squeeze and relax grows longer, by 2 percent to 5 percent.
Test results were obtained from study participants who had undergone high-tech magnetic resonance imaging of the heart - tagged MRI - which measures individual muscle segment changes with each heartbeat.
We need stem cell therapies and other therapies that can reverse the changes that happen as our hearts age.
Our hearts eject less blood on every beat each year we get older.
The current gold standard, he says, is the heartís ejection fraction, a ratio of the amount of blood pumped out with each heartbeat to the total volume of blood available for pumping. An ejection fraction of 50 percent to 65 percent is considered normal.
Study results showed that ejection fraction actually rose by 0.01 percent with every year. But Lima calls this figure misleading because the total amount of blood available for pumping, the bottom number in the ratio, decreases as the size of the heart cavity shrinks and heart walls thicken, falsely boosting test results when heart function is actually failing.
When researchers separated the numbers, the actual amount of blood pumped out by the heart fell by 8 milliliters per year, says Lima, an associate professor at The Johns Hopkins University School of Medicine and its Heart Institute.
All of these changes will become reversible. The aging process is not set in stone. The changes that come with aging will some day be reversed with gene therapies, cell therapies, and other treatments.
|Share |||Randall Parker, 2007 November 04 09:40 PM Aging Mechanisms|