Coronary artery calcification (intimal and medial calcifications) increases the complexity of percutaneous treatment strategies in coronary interventions. It contributes to:
arterial wall stiffness
suboptimal stent delivery and expansion
in-stent restenosis
high rates of stent thrombosis
the need for subsequent target lesion revascularisation after endovascular interventions.
Standard endovascular treatment options for modifying calcium or plaque during percutaneous coronary intervention (PCI) include balloon angioplasty using standard or high-pressure non-compliant balloons; cutting or scoring balloons; and stenting with or without coronary atherectomy (such as rotational, orbital or laser atherectomy). These treatments aim to allow optimal stent expansion and achieve maximal luminal gain. But they may sometimes lead to localised wall injury, balloon rupture or the risk of coronary vessel dissections or perforation. Intravascular lithotripsy is another endovascular treatment option for PCI.
Addressing calcified coronary lesions during PCI presents a significant challenge. Calcified plaques can hinder stent deployment and expansion, increasing the risk of complications such as arterial dissection or inadequate stent expansion. Existing options for managing heavily calcified coronary arteries during PCI such as balloon angioplasty may not be effective in fracturing severe calcifications. By using sonic waves to fracture calcium deposits, intravascular lithotripsy may be an efficient approach to managing calcified coronary arteries and may lead to better stent placement and improved patient outcomes.
In this procedure, intravascular lithotripsy is administered to the calcified coronary artery before the stent is placed during PCI.
A percutaneous guidewire is passed through a catheter inserted from the radial or femoral artery into the coronary artery. Then, an intravascular lithotripsy catheter with embedded emitters enclosed in an integrated angioplasty balloon is passed and connected to an external generator with a cable. The catheter is advanced to the target lesion guided by X-ray imaging of radio-opaque markers on the catheter. The balloon is then inflated with a saline and contrast solution to ensure contact with the vessel wall. The lithotripsy cycle is then started. For every cycle, the catheter emits localised, high-energy, pulsatile, unfocused, circumferential, sonic, pressure waves (lasting microseconds). These waves pass through the inflated balloon into the wall of the coronary artery. As the waves travel into the wall and the connective tissue, they disrupt calcium deposits (both intimal and medial) by micro-fracturing the calcified lesions. The balloon is then deflated to allow blood supply to return to the heart.
The cycle can be repeated until the lesion has expanded enough to allow optimal stent placement or the total pulses available are used.