Intravascular lithotripsy for calcified arteries in peripheral arterial disease

Peripheral arterial disease (PAD) is caused when a build-up of fatty substances (plaque) in the arteries restricts blood supply to the limbs, usually the legs. The plaque can calcify and become like bone. This is known as intravascular calcification, and it is particularly common in people with diabetes mellitus or chronic kidney disease. The most common initial symptom of PAD is leg pain while walking, known as intermittent claudication. If blood flow is severely restricted, chronic limb-threatening ischaemia (CLTI, also known as critical limb ischaemia) can develop. Symptoms include severe pain at rest, ulceration or gangrene. CLTI is associated with a high risk of amputation and death, and the presence of arterial calcification increases these risks.

Management of PAD is described in NICE's clinical guideline on peripheral arterial disease. For CTLI, revascularisation using percutaneous transluminal angioplasty (with or without stent placement) or a bypass graft is recommended. Atherectomy devices that vaporise, cut or grind away plaque within the artery are sometimes used alongside balloon angioplasty. If revascularisation is not an option, major amputation may be offered.

Arterial access is established as for a standard angioplasty, usually through the femoral artery in the groin. An angioplasty balloon with a source of acoustic pressure waves (lithotripsy emitters) is introduced and inflated next to the heavily calcified arterial plaques. The pressure exerted by the balloon is too low to expand the vessel but high enough to ensure good contact between the surface of the balloon and the arterial walls. Acoustic pressure waves are then transmitted from the balloon, fracturing superficial and deep calcium within the arterial wall. As with standard angioplasty, a stent is sometimes inserted after the lithotripsy to keep the artery patent. The procedure is used as a preparatory treatment for balloon angioplasty or as an alternative to standard angioplasty.

The aim of intravascular lithotripsy is to improve the blood flow in the affected limb and prevent the need for amputation.