MONDAY, Sept. 27 (HealthDay News) -- Implantable cardioverter
defibrillators (ICDs) have saved the lives of tens of thousands of
Americans at risk for sudden cardiac death because of serious heart
But these medical devices have gotten a bad reputation in recent
years, mainly because the electrical wires, or leads, that connect
the ICD to the heart can sometimes fracture, causing patients to
unnecessarily receive painful shocks.
Now, a new study suggests that doctors can cut the relative risk
of accidental shocks in half simply by downloading upgraded
software into the ICD during a routine office visit.
The Lead Integrity Alert (LIA) software checks the device for
suspicious electrical signals six times a day, and if problems are
detected, alerts the patient with an audible beep every four hours,
according to the study, which was published in the Sept. 27 issue
In contrast, standard ICD software usually monitors the device
for signs of fractures and other mechanical problems just once a
day, and notifies the patient of any abnormalities with a single
alert at the same time every day.
The biggest advance, said study author Dr. Charles Swerdlow, a
cardiac electrophysiologist at the Cedars-Sinai Heart Institute in
Los Angeles, is that LIA software can detect electrical changes
that signal a wire fracture and recalibrate the device to delay an
inappropriate shock from occurring.
"The software basically makes the devices less trigger-happy," said Swerdlow, who is a clinical professor of medicine at the University of California, Los Angeles' David Geffen School of Medicine.
The study was funded by Medtronic Inc., which developed the LIA
software for use with the company's ICDs that are connected to a
specific type of lead that has been particularly prone to
fractures. (That lead, known as Sprint Fidelis, was removed from
the market in 2007.)
"Some doctors have been pulling these leads out prophylactically because they're worried about fractures, but what they often don't consider is that there are significant risks associated with lead replacement surgery," noted Swerdlow, who added that he hoped these findings encourage doctors to consider other options before replacing ICD leads.
Earlier this year, researchers reported that a new type of ICD
that can be implanted just under the patient's skin and eliminate
the need for electrical leads altogether may be just as effective
as conventional models, but electrophysiologists say larger and
longer-term studies are needed to prove their safety and
For the software study, Swerdlow and his co-authors compared the
experience of 426 patients prior to surgery to replace fractured
leads. Half of the patients received standard daily monitoring and
half were monitored with the addition of the downloadable LIA
software. Among the patients who had standard monitoring, 70
percent received one or more inappropriate shocks, compared with
only 38 percent of those who were monitored with the help of LIA
software. Five or more inappropriate shocks were delivered to 50
percent of the patients who received standard monitoring, but only
25 percent of patients with LIA.
The researchers also found that 72 percent of patients with LIA
had no inappropriate shock, or had at least three days warning
prior to an inappropriate shock, compared with only 50 percent of
those who received standard monitoring.
Many electrophysiologists began using the software soon after
the FDA approved it in August 2008, said Dr. Andrea M. Russo,
director of Cardiac Electrophysiology and Arrhythmia Services at
Cooper University Hospital in Camden, N.J.
"Inappropriate shocks are much more damaging, psychologically, [than necessary electrical jolts] so we need to aim to eliminate every shock that's unnecessary," said Russo, who is a professor of medicine at UMDNJ-Robert Wood Johnson Medical School in New Brunswick, N.J.
Now that more and more patients with ICDs can be monitored at
home with the use of remote systems that send information to
doctors over a telephone line, "getting patients to come into the
office so we can download the software is sometimes the hardest
part," said Russo.
Swerdlow said other ICD software now under development will
hopefully making the device "smart enough to know when a lead is
broken and withhold a shock altogether." But that advancement, he
said, "is a much trickier thing because the penalty for being wrong
is really high. If someone crashes their iPod, they're out of songs
for a while. But if a patient crashes their defibrillator, they can
An estimated 114,000 patients have surgery to implant or replace
ICDs every year, according to the American Heart Association.
For more on ICDs, visit the
American Heart Association.