Pacemakers Change Biology of the Heart( Study with dogs shows devices much mo...),Health

Study with dogs shows devices much more than a mechanical fix for ailing patients

FRIDAY, March 21 (HealthDay News) -- In dogs with damaged hearts, implanted pacemakers triggered fast improvements in tissue levels and the activity of a number of proteins crucial to heart health, says a Johns Hopkins study.

The researchers said their findings are believed to be the first detailed chemical analysis of the biological effects a pacemaker has on the heart. This new information could lead to improvements in the use of combined pacemaker/drug treatments for congestive heart failure patients.

"We are learning that pacemaker therapy does profoundly more than just mechanically correct how the heart beats; in fact, it produces major chemical changes that benefit the muscle," lead investigator Khalid Chakir, a postdoctoral cardiology research fellow at Hopkins, said in a prepared statement.

In this study, Chakir and colleagues induced "wobbly, discoordinated contraction" in the hearts of 22 dogs. In half the dogs, this asymmetric heart failure was allowed to take its natural course. The other dogs received a cardiac pacemaker.

Tissue analysis found major changes in the production or activity levels of 17 proteins known to be involved with heart cell stress, survival and death. These changes were especially notable in the dogs that didn't have their hearts "retuned" by a pacemaker.

In the dogs that did receive a pacemaker, the tissue levels and activity of these proteins were restored toward normal. The findings were published online in Circulation.

"Our results really help explain how pacemakers act much like a drug, actually changing the biology of the heart, and also explain why people can feel so much better after just two to six months with the device," study senior investigator Dr. David Kass, a cardiologist and professor at the Johns Hopkins University School of Medicine and its Hea
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