In patients with coronary artery disease, too much plaque (cholesterol, calcium, and fat) builds up along the walls of the arteries, and the heart doesn’t get enough blood. To counteract this, we may place a small, cage-like structure called a stent in the artery to widen it and allow blood to flow freely.
However, some stents (about 5%) can’t expand fully if the artery is too hardened by calcium deposits. That’s when an interventional cardiologist has to manually drill through the plaque by using a catheter with an abrasive tip or crown – sort of like a Roto-Rooter for plumbing – prior to placing a stent. Though these atherectomy procedures can be effective, there is a risk of damaging or puncturing the artery.
UT Southwestern is among the first health care centers in Texas to offer an exciting new technique called intravascular lithotripsy (IVL) to improve the effectiveness of stents in calcified arteries. Approved by the U.S. Food and Drug Administration (FDA) in February 2021, IVL is based on technology developed in the early 1980s that uses shock waves to break apart kidney stones.
Similarly, IVL employs sonic waves to create cracks in the calcium deposits in an artery, providing just enough wiggle room for the stent to properly expand. The process improves blood flow with no pain and less arterial wall damage.
How intravascular lithotripsy works
Intravascular lithotripsy is performed through a cardiac catheterization procedure. The cardiologist makes a small incision in the leg or arm and inserts a thin, flexible tube (catheter) equipped with special sonic wave emitters and a slender balloon into a blood vessel.
Under advanced imaging guidance, we thread the catheter to the calcified artery. Once in place, the balloon is expanded with a liquid solution to transfer the sound wave energy efficiently. The emitters deliver focused sound waves that pass safely through the soft tissues of the artery to crack the calcified plaque.
Once the calcified plaque is cracked, we can place a stent that will fully expand, restoring healthy blood flow. The procedure takes approximately an hour.
Combining traditional and new technology
Studies leading up to FDA approval have shown IVL to be safe and effective. The Disrupt CAD II trial showed the procedure carries a low risk of potential complications, such as blood vessel damage or perforation. Disrupt CAD III further validated the safety of the procedure, leading to FDA approval.
The procedure is also a timesaver – to perform an atherectomy, we must use different catheters and equipment to grind down the calcium deposit and place the stent. For IVL, we can crack the calcium and place the stent through the same catheter.
Atherectomy remains an effective way of clearing excessive calcium deposits, and some patients still need to have calcified plaque removed via atherectomy to fit a stent inside a blocked blood vessel. But then, we can still use IVL to fracture the remaining calcification and fully expand the stent.
In this scenario, we still open the blood vessel but for a shorter procedural time and with less aggressive grinding.
The future of treating coronary artery calcification
Intravascular lithotripsy is one of the first new tools to treat calcified coronary disease, and it won’t be the last. Future studies will continue to assess long-term benefits and determine whether we can use intravascular lithotripsy to rupture calcium behind a stent that is already in place. This may have value for previously placed stents that are under-expanded, or smaller than intended, due to underlying calcium.
In the future, rather than placing a new stent inside a failed one or into a recalcified artery – which is unlikely to do much good long term – we could break up the calcium, allowing the existing stent to fully expand properly.
Of course, any invasive procedure involves some risks. Cardiologists at UT Southwestern use a team-based approach to determine which patients are most likely to benefit from IVL, and engage in shared decision making with patients around the best therapy for each individual.
Our team is always seeking better methods to treat coronary artery disease, whether that means refining existing treatments or discovering new therapies. There is always room to do more for patients with heart complications, and we are pleased to take a leading role in these vital endeavors.