"This approach may play a significant role in targeting a subset of heart failure patients for whom we need to be more aggressive if we don't see early improvement in heart rate variability," Gilliam said. "We would expect that as their heart function improves after implantation, their heart rate variability would improve as well."
Heart failure is a condition marked by the inability of the heart muscles to pump enough oxygen and nutrients in the blood to the body's tissues. Also known as congestive heart failure, its many causes include infections of the heart, coronary artery disease, high blood pressure, previous heart attacks and valve problems. An estimated 4.7 million Americans suffer from the condition, with 400,000 new cases reported each year. Roughly one-half of patients die within five years of diagnosis.
Although there is no cure, drugs can improve the strength of the heartbeat (digoxin), relax blood vessels (ACE inhibitors)or remove the excess buildup of fluid in the lungs (diuretics). Implantable devices are the latest options in preventing arrhythmias that can lead to sudden death, with CRT-Ds being the latest technology.
CRT-Ds perform two main functions. First, the devices electrically stimulate both sides of the heart in coordinated fashion, which optimizes the contractability of already weakened heart muscle. Second, the defibrillator "shocks" the heart back into normal rhythm whenever the heart beats irregularly.
In addition to maintaining the heart, the devices also collect heartbeat-by-heartbeat data that can be downloaded from the device and entered into a computer. One use of the data in this trial was to create a "footprint," or visual representation, of a patient's heart rate variability over time. Patients w
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Contact: Richard Merritt
Merri006@mc.duke.edu
919-684-4148
Duke University Medical Center
7-Mar-2005