Published: May 24, 2010
Removing Tiny Filter Embedded in Vein Takes Stanford Hospital's Unique Expertise
STANFORD, Calif. - (BUSINESS WIRE) - Over the years, Susan Karnstedt had gotten used to the intermittent pain
in her abdomen, chalking it up to her diet, or perhaps to her physically
active lifestyle, as a water skier and yoga enthusiast.
"The abdominal pain continued to get progressively worse, and was pretty
debilitating," the 44-year-old Portola Valley resident said, describing
how she was feeling when she visited the doctor earlier this year.
Karnstedt was well aware of her history of blood clots, but that still
didn't prepare her for what she then learned: her pain could be traced
to a filter that had been inserted more than 18 years ago in her
inferior vena cava, the big vein that goes from the lower half of the
body to the heart. Part of it was now poking through her intestines.
Removing this permanent-type umbrella-shaped device would not even be
considered at most hospitals today, but Karnstedt was fortunate to be
referred to interventional radiologist William Kuo, MD, at Stanford
Hospital & Clinics. His team is believed to be the first in the world to
apply endovascular laser technology to successfully retrieve permanently
embedded IVC filters, and Stanford is currently the only hospital in the
country where these procedures are routinely performed. "It is now
possible to safely explant many of these devices that were previously
irretrievable," Kuo said.
To fully appreciate Karnstedt's remarkable recovery, it's necessary to
go back to 1992, when the device, known as a Greenfield Filter, was
first inserted. She had gone to a Chicago emergency room barely able to
breathe with pain and swelling in her left leg. There she was diagnosed
with a life-threatening deep-venous thrombosis and pulmonary embolism -
a blood clot that had formed in a vein in her pelvis and traveled to her
lungs.
As part of the treatment, doctors inserted the Greenfield filter into
her inferior vena cava, the big vein that carries deoxygenated blood
from the lower half of the body to the heart.
The metallic filter looks like an umbrella frame, with multiple spidery
legs. Many doctors now recognize the difficulty with filters that are
left in for a long time - they can eventually become the source of a new
clot and shut down the inferior vena cava. What's more, the legs of the
filter can erode through the IVC and puncture adjacent organs. It is
believed that the risk of developing such complications increases the
longer a filter remains in place.
But back in 1992, Karnstedt's IVC filter was thought to be harmless over
a lifetime and was intended as a permanent implant.
Forward to 2010. Karnstedt and her family had moved to the Bay Area,
where she consulted with a hematologist regarding a long-term
anti-coagulation strategy in light of her high-risk condition. A CT scan
was ordered to check that Karnstedt's IVC filter was free of clots, and
that blood was flowing through stents that had been inserted into her
iliac vein in the years following the 1992 procedure. What the scan
turned up was unexpected and frightening.
Although no clots were identified, over the course of 18 years
Karnstedt's IVC filter had turned lethal. "Over time, a few of the
filter legs had eroded through, perforating her IVC, and one of them had
impaled her intestines," said Kuo. "The filter tip had also become
tilted and was embedded within the IVC wall. The degree of filter leg
penetration through the intestines was shocking and undoubtedly the
cause of her chronic and worsening abdominal pain." Karnstedt described
it as a "fork poking" into her intestines.
Karnstedt also consulted with experts in her native Chicago where the
filter was originally placed. According to Karnstedt, she was told that
no one there had removed a non-retrievable filter and that permanent IVC
filter removal had never been successfully accomplished. So she turned
to Kuo and SHC.
As an interventional radiologist who specializes in vascular disease and
management of complex IVC filter cases, Kuo has seen more and more
patients referred to him from around the country for treatment of
problematic IVC filters. These patients have inspired him to pioneer
alternative methods that can be used to safely remove these devices. The
cumulative results of years of research, coupled with ongoing studies,
have resulted in new protocols for managing these challenging, high-risk
cases in patients who otherwise would have no treatment option.
Kuo has published his data on complex and high-risk filter retrieval in
the Journal of Vascular and Interventional Radiology, and he recently
presented new data on use of his laser technique at this year's Society
of Interventional Radiology meeting.
Kuo's expertise convinced him that he could potentially use these
alternative methods to help Karnstedt, who had by far the longest filter
implant with the most severe intestinal perforation he had ever seen.
"Every filter patient is unique, and thus the treatment must be
meticulously planned and personalized to fit the patient," Kuo said.
On April 13, using real-time X-ray fluoroscopy to guide him, Kuo made a
4-mm incision in Karnstedt's neck, inserted a catheter into her jugular
vein and guided it toward the filter in her vena cava. He then formed a
special wire loop through the embedded filter and carefully began to
realign it. The technique also allowed him to free the filter leg that
had perforated through her intestines.
Next, through the same incision, Kuo advanced a special endovascular
laser around the legs of the filter, and used this to carefully ablate
the adherent tissues tethering the filter in place. This was a delicate
maneuver as Kuo attempted to separate the scar tissue, which had formed
around the filter over 18 years, without injuring the underlying normal
vessel. After hours of working in this fashion, he was able to free,
collapse, and completely remove the filter without damaging the
underlying vena cava.
There was no need for open surgery, and following the procedure, no
stitches were required - just a Band-aid on her neck site.
Side effects? "None," Karnstedt said. "I was done at 2 p.m., and home by
6 p.m., having dinner with my family."
For her part, the Portola Valley mom said she is happy to be pain free.
"I could have gone to dance class the next morning," she said about the
recovery time. Instead, she and her family celebrated with a stroll on
the beach at Half Moon Bay.
About Stanford Hospital & Clinics
Stanford Hospital & Clinics is known worldwide for advanced treatment of
complex disorders in areas such as cardiovascular care, cancer
treatment, neurosciences, surgery, and organ transplants. Consistently
ranked among the top institutions in the U.S. News & World Report
annual list of "America's Best Hospitals," Stanford
Hospital & Clinics is internationally recognized for translating
medical breakthroughs into the care of patients. It is part of the
Stanford University Medical Center, along with the Stanford University
School of Medicine and Lucile
Packard Children's Hospital at Stanford. For more information, visit http://stanfordmedicine.org.
Photos/Multimedia Gallery Available: http://www.businesswire.com/cgi-bin/mmg.cgi?eid=6303366&lang=en
Stanford Hospital & Clinics
Liat Kobza, 650-723-1462
lkobza@stanfordmed.org
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