'Jackhammer' wire helps crack open blocked coronary arteries: researchers
Published Thursday, September 27, 2018 1:02AM EDT Last Updated Thursday, September 27, 2018 1:35AM EDT
TORONTO -- In what's being touted as a world first, Montreal researchers have been able to bust open coronary arteries completely blocked with calcium deposits using an innovative device that produces a "jackhammer" effect.
Doctors at the McGill University Health Centre are testing the SoundBite Active Wire in a small group of patients who have "chronic total occlusion" of one of their coronary arteries, which severely restricts blood flow to the heart.
Principal researcher Dr. Stephane Rinfret, chief of interventional cardiology at MUHC, said Wednesday the condition affects about 20 per cent of people with coronary atherosclerosis, often called hardening of the arteries.
Interventional cardiologists typically treat arteries with varying degrees of plaque buildup using angioplasty -- a procedure in which a fine guide wire and catheter are fed into the blood vessel and a tiny balloon is inflated to widen the opening. A stent is usually inserted to keep the vessel clear and blood flowing freely.
But with chronic total occlusion, or CTO, safely breaching a wall of rock-like calcium with a traditional guide wire is a highly complex, time-consuming procedure, which many interventional cardiologists are reluctant to perform because it can have a poor success rate, said Rinfret, who specializes in complex angioplasties.
Between 10 and 50 per cent of all CTO angioplasties are unsuccessful, primarily because ordinary wires can't break through the wall of calcium, he said.
The SoundBite guide wire, developed by a Quebec company named SoundBite Medical Solutions, provides a new twist that could help increase success rates.
The wire is connected to a shock wave generator, which causes it to vibrate like a jackhammer inside the artery, allowing it to create cracks in the calcium blockage while leaving the walls of the blood vessel unharmed.
"This wire could mean the difference between the success and failure of a CTO angioplasty because it will be able to break through areas where other guides fail to penetrate," said Rinfret. "It will clear the way and allow us to treat the diseased artery."
Animal studies have shown the device doesn't pulverize the calcium blockage to create debris -- which could lead to heart attack-causing clots -- but opens up tiny fissures that allow a second guide wire and balloon catheter to pass through.
"We're going to use it as a point-and-shoot," he said, noting that another version of the guide wire was used for the first time in 2016 to clear blockages in leg arteries.
MUHC researchers performed the first CTO angioplasty using the SoundBite wire in June and have since done two more. They plan to do 10 in total as part of a preliminary study, along with another 10 that will be performed by colleagues at Columbia University in New York.
That study will be expanded to include 150 patients at several more centres in Canada and the U.S., with the aim of demonstrating that the device is safe and effective.
The goal is to have the SoundBite approved for widespread use by regulatory agencies like Health Canada and the U.S. Food and Drug Administration, said Rinfret. An estimated 300,000 people in North America could benefit from the technology.
"The problem is there are too few patients who have access to chronic total occlusion angioplasty" because relatively few interventional cardiologists feel confident tackling the complicated procedure, he said.
"What we need is to make sure pretty much everyone is more comfortable in attempting those vessels ... so more patients have access that really changes their life and quality of life."