Doctor uses laser technology to remove dangerous permanent clot filter

Deep Vein-Thrombosis or DVT affects about 2 million Americans each year. DVT happens when a blood clot forms in the leg and blocks circulation.

Doctors used to implant permanent filters to prevent the clot from traveling to the lungs.

But now, many believe some of those devices do more harm than good.

Although removing a once-permanent filter was risky, it was necessary for one woman.

Susan Karnstedt and her family have always lived active lives.

Susan said, "We're big hikers, bikers, waterskiing, wake-boarding. We love all the snow sports."

But all those adventures stopped when Susan suffered severe abdominal pain.

Susan said, "I would wake up, throbbing pain, would take a painkiller, would sleep with a heating pad."

For months, she thought it was her diet that was making her sick. But a CT scan showed something else. A device she had implanted 18 years ago to treat a clotting condition was impaling one of her organs.

Susan said, "There were three of the prongs clearly perforating into my small intestine. I was like, 'Oh my God,' you know."

The device was a filter that doctors inserted to catch a blood clot before it traveled to Susan's lungs. Back then, they thought it was helpful. Now, it is proven to be dangerous.

Dr. William T. Kuo, M.D., is the Director of the Stanford IVC Filter Clinic at Stanford University Medical Center. He said, "We're starting to realize that the longer a device is left implanted, the more chance there is of a complication occurring."

Susan's filter had formed scar tissue around her vein. Doctors told her leaving it in would cause more damage, but removing the permanent device was too risky.

Susan said, "The thought was trying to remove it would kill me. I would bleed out on the table."

Then, she found Dr. Kuo, who pioneered a new procedure that uses laser technology.

Dr. Kuo said, "Before we conducted our research in this area, there was no option for treating patients."

Dr. Kuo made a four-millimeter incision in Susan's neck and carefully guided a catheter down to her vena cava. He used a special laser to separate the scar tissue and then removed the filter without any damage to her vessels.

What was supposed to be a life-threatening surgery turned into a surgery that saved Susan's life.

Susan said, "The pain was gone. I felt great."

With no filter, she is active again and enjoying the outdoors.

Dr. Kuo said since Susan's successful procedure, dozens of patients around the country have contacted him and been treated.



BACKGROUND: Deep vein thrombosis (DVT) is a blood clot that forms in a vein deep in the body. The clots occur when blood thickens and clumps together. Most deep vein blood clots occur in the lower leg or thigh. They can also occur in other parts of the body. A blood clot in a deep vein can break off and travel through the bloodstream. When the clot travels to the lungs and blocks blood flow, the condition is called pulmonary embolism (PE). PE can cause damage to the lungs and other or organs. It can also lead to death. (SOURCE: National Institutes of Health)

ONE PATIENT'S STORY: Susan Karnstedt was diagnosed with a life-threatening PE in 1992. A blood clot had formed in a vein in her pelvis and had traveled to her lungs. Doctors inserted a device, known as a Greenfield Filter, into her inferior vena cava, which is the large 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. The permanent device was designed to catch a blood clot before it traveled to Susan's lungs. However, the filter had formed scar tissue around Susan's vein and was poking through her intestines. Susan was experiencing extreme abdominal pain.

REMOVING FILTERS: Most doctors wouldn't consider removing the permanent filter, but Susan was referred to interventional radiologist William Kuo, M.D., from Stanford Hospitals and Clinics. His team is the first in the world to apply endovascular laser technology to successfully retrieve permanent filters. Using real-time X-ray fluoroscopy to guide him, Dr. Kuo made a 4-millimeter incision in Susan'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. 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. He separated scar tissue that had formed around the filter for 18 years. He was able to free, collapse and completely remove the filter without damaging the underlying vena cava. Susan did not require any stitches; she only needed a Band-aid on her neck site. (SOURCE: Stanford Hospitals & Clinics Press Release)

Stanford Hospitals & Clinics
Department of Radiology
(650) 724-7362

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