stanford medicine



Down to the wireA new way to clear clots from lungs

William Kuo, MD, was the on-call interventional radiologist one Friday night three years ago when he received a call from the intensive care unit at Stanford Hospital & Clinics. He was asked to attend to a 62-year-old woman who had collapsed and was rushed to the emergency room with blood clots in her lungs.

“I get very emotional when I think about what happened,” says Kuo, assistant professor of radiology. “I could immediately see the patient was not doing well. The ICU team had notified the family that she was going to die very soon.”

What happened that night set Kuo on a three-year mission to investigate the safety and effectiveness of a new treatment — catheter-directed thrombolysis — for the patient’s condition, acute pulmonary embolism.

As in most cases of pulmonary embolism, blood clots had first formed in the patient’s legs, then traveled to her lungs, interfering with oxygenation and the heart’s ability to pump blood into the lungs. Because of the blood clots, she was quickly suffocating to death. The ICU staff had already done everything they could.

Kuo was initially consulted to perform a minor procedure — placement of a special filter in the major abdominal blood vessel to prevent more clots from traveling to the lungs, but he knew it would do little to save her. Then an idea came to him.

Leslie Williamson
William Kuo
William Kuo wants more physicians to know about a new way to open blocked vessels.

“I had been reading about experimental catheter-based treatments to remove these clots from the lungs,” Kuo says. “I told the staff, ‘We can do more than just insert a filter. We can go after these clots using specially designed catheters.’ The ICU staff was at first skeptical, but I just kept insisting because I knew it might save her life. We obtained consent from the family and went ahead with it.”

He quickly made a small incision in the patient’s neck, inserted a catheter — a thin plastic tube — into the blood vessel. He then used real-time X-ray images (fluoroscopy) to guide the catheter, navigating through the heart and finally reaching the blood clots within the lungs. First, he injected clot-busting medicine through the catheter directly into the clots. Then, he used the catheter to mechanically break them up. Finally, he suctioned them out.

The results were immediate. The patient’s oxygenation improved, her blood pressure started to rise and she no longer required the blood-pressure drugs to keep her alive. The angiogram showed that blood was now able to flow into her lungs and the blood clots were much smaller.

“We just stood there,” Kuo says, “and we were amazed that the treatment had saved her life. She walked out of the hospital nine days later.”

But that was just the beginning for Kuo.

“At that moment three years ago, I recognized that this was a potentially life-saving procedure, but I also realized that few physicians were aware of it. The experience from that case really inspired me to begin my clinical research.”

Results from that research, a meta-analysis of scientific data from around the world, appeared in a report in the November issue of the Journal of Vascular and Interventional Radiology. The study shows that when catheter-directed therapy is used to treat dangerous blood clots, it saves lives.

Tracie White






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