For decades doctors have been seeking better ways of treating obstructions in coronary arteries — especially blockages made up of calcium — a factor that has produced several innovations, including miniature “rotoblades” that grind it up the way plumbers attack gunk in pipes.
Now, doctors at St. Francis Hospital in Flower Hill have turned to something far gentler: sound waves, an evolving technique that loosens stubborn calcium from arterial walls. This minimally invasive method of dislodging blockages is part of a nationwide clinical trial that promises to restore blood flow by breaking up calcium at the speed of sound.
“This is amazing. It’s actually space-age technology,” said Dr. Richard Shlofmitz, chairman of cardiology at St. Francis. He said the procedure is formally known as intravascular lithotripsy, a version of the same principle involved in breaking up kidney stones. That process is called kidney shock wave lithotripsy, which has been successfully used since the 1990s.
For decades, doctors have had three ways to deal with coronary artery blockages: medications, such as statin drugs; stents, the mesh-like tubes that prop open arteries blocked with plaque, and coronary bypass surgery.
Plaque is largely composed of cholesterol, fatty deposits, calcium, cellular debris and fibrin, a clotting substance in the blood. Calcium is a solid and with the other plaque components forms a potentially deadly dam in arteries, blocking the free-flow of oxygenated blood.
Some patients whose blockages are mostly made up of calcium do not fare well with standard treatments and have had a poor prognosis. Severely blocked arteries can cause severe chest pain — angina — and increase the risk of heart attack.
“You can fix many blockages with stents and angioplasty,” Shlofmitz said of putting a stent in place by using a thin catheter with an attached balloon. The inflated balloon presses the goo that has collected in the artery out of the way as the stent is deployed. The balloon and catheter are removed.
“But when the obstruction is made up of calcium, it’s hard to open it up,” Shlofmitz said.
While balloon angioplasty can be used to force open stubbornly blocked arteries, it may be impossible to put in a stent, and even with the plaque pushed aside it is not always a permanent solution.
“The blockage can return,” Shlofmitz emphasized. “That’s called restenosis.”
Pulses of sound waves, doctors are discovering, can break up calcium in the arteries and ultimately may provide hope for patients with severe blockages. This method of addressing hard-to-treat plaque has been approved in Europe and is being studied in Japan.
Patients who are having their plaque “shocked away” at St. Francis are wheeled into a catheterization laboratory where a long thin tube — a catheter — containing a balloon and a series of sonic wave-emitters are advanced through a vessel in the leg to reach the obstruction blocking the heart.
When the obstruction is reached, the doctor operates a handheld device that both opens the balloon and generates pulses of sonic wave energy. Acoustic waves break the plaque into dozens upon dozens of microfractures, allowing a stent to be deployed. The minuscule particles of calcium are swept out of the body as waste, Shlofmitz said.
About 610,000 people die annually of heart disease in the United States, and of that total more than half — 366,000 — succumb to coronary artery disease, according to data from the National Heart, Lung, and Blood Institute.
Lyn Santiago, the research nurse who is enrolling patients in the St. Francis clinical trial, called this method of treatment “painless.”
So far, 12 patients have been treated with sound waves at St. Francis, where the team hopes to enroll a total of 60 in the coming months, Santiago said.
“Patients are free of chest pain. They feel better,” she said of the procedure.
The technology was developed by Dr. Todd Brinton, a cardiologist and bioengineer at Stanford University.
Brinton presented scientific data on sonic wave treatment two years ago in Paris, based on findings from the European arm of his research. He reported that not only do sound waves effectively treat patients with calcium blockages, there are no side effects from the shock wave treatment, he said.