por Lynn Shapiro
, Writer | September 22, 2009
In a new post-marketing study, Medtronic showed that its fluid monitoring system, OptiVol, is a more accurate predictor of worsening heart failure than daily weight monitoring in patients wearing implantable devices.
Results showed that Medtronic's OptiVol fluid status monitoring system, which measures changes in fluid build-up in the chest cavity, predicted 76 percent of future heart failure events, compared to 23 percent detected by weight monitoring alone.
Although the Optivol feature, which comes bundled with Medtronic's pacemakers and defibrillators, won approval in 2004, "we decided to test the device again, since some physicians were unaware of it and others were waiting for information like this," William T. Abraham, M.D., professor of Medicine and Physiology at The Ohio State University and principal investigator of the study, tells DOTmed News.
"Wire and Can" Concept
Explaining how the device works in layman's terms, he says, "there's a little electrical impulse that goes from a wire implanted inside the heart to the 'can' which is the pacemaker or resynchronization device. By measuring the flow of electricity between wire and can, clinicians can determine if lungs are wet."
Dr. Abraham notes, "What really is unique about this study is we compared the Optivol to current clinical practice, where patients weigh themselves daily to make sure they're not retaining fluids that would eventually go to the lungs and require hospitalization and treatment with intravenous diuretics."
He says that daily weight monitoring is apparently ineffective for many, as there are nearly 1.2 million heart-failure hospitalizations each year.
One of the problems with weighing oneself daily is that some days patients forget to get on the scale, he says. Optivol records weight automatically.
Water Weight Precedes Symptoms
The good news, Dr. Abraham says, is that fluid retention leading to hospitalization occurs over many days or weeks before patients becomes symptomatic. If Optivol finds that patients are gaining dangerous amounts of water weight, physicians can treat patients with oral medications proactively, saving lives and costly hospitalizations.
He reminds DOTmed readers that while Medtronic's device is the only one currently on the market, St. Jude and Boston Scientific have developed similar devices, now undergoing clinical trials.