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Sciahbasi et al. Vessel Plus 2023;7:19 https://dx.doi.org/10.20517/2574-1209.2023.22 Page 3 of 12

[15]
rotational atherectomy versus conventional balloon dilatation before stent implantation and randomized
data for orbital atherectomy versus standard of care are lacking. Two other drawbacks of this method are
the need for a dedicated wire and the inability to protect side branches with a second wire.

A new and promising device for the treatment of highly calcified coronary lesions is the intravascular
lithotripsy (IVL) balloon, which features high efficacy, low complication rates, and simplicity of its use.

INTRAVASCULAR LITHOTRIPSY BALLOON: DEVICE DESCRIPTION
IVL is a technique derived from extracorporeal shock wave lithotripsy used for calcium modification that
delivers acoustic pressure waves (shock waves) aimed to disrupt the calcium by creating multiplane micro-
fractures in the plaque . The first extracorporeal shock wave lithotripsy was reported in the 1980s for the
[16]
treatment of urolithiasis using high-energy acoustic shockwaves . The extracorporeal lithotripters generate
[17]
a waveform characterized by a brief pulse lasting about 5-10 μs and characterized by a near-instantaneous
jump to a peak positive pressure (compressive wave) with an abrupt transition (the “shock”), consisting of a
falling pressure to zero in ≈1 μs, followed by a negative pressure trough (“tensile wave”) in almost 3 μs .
[18]
Shockwaves travel safely through soft tissue with negligible effect due to similar acoustic impedance
between water and soft tissues, whereas the fracturing effect appears when sonic waves hit tissues with
different acoustic impedance, such as the calcified tissue.

The application of lithotripsy to endovascular medicine refers to the use of a balloon-based technique
characterized by miniaturized electrohydraulic lithotripters integrated onto the shaft of a balloon
angioplasty catheter system. The balloon is filled with contrast and saline in order to allow apposition to the
vessel wall and provide a similar acoustic fluid-tissue interface to deliver the sonic pressure waves created by
the miniaturized lithotripters. The system could generate peak positive pressure in the range of 50 atm .
[19]
The IVL system (Shockwave Medical, Santa Clara, CA, USA) is made up of three components: a generator,
a connector cable, and a single-use sterile disposable catheter that embeds the lithotripsy emitters . The
[20]
semi-compliant balloon catheter, which is 6 Fr compatible and can be used over a 0.014" guidewire,
incorporates two radiopaque lithotripsy emitters 6 mm apart and two standard markers placed proximally
and distally to the edge of the balloon. Compared to non-compliant balloon crossing profiles
(0.033”-0.035”), coronary IVL balloons have a thicker profile (0.043”-0.046”) and are available in diameters
ranging from 2.5 to 4.0 mm (with 0.5 mm increments) and a standard length of 12 mm. This catheter
balloon is programmed to deliver 10 pulses in sequence at a frequency of 1 pulse/second, which can be
repeated for a maximum of 80 pulses per catheter. A push button on the connector cable allows manual
control of the delivery of the electric pulses.

The IVL procedure is a quite simple procedure that does not require high-level additional training for
interventional cardiologists but just some simple explanations. The first step is the choice of the shockwave
balloon that has to be sized according to the reference vessel diameter (ratio 1:1). Then, the IVL catheter is
introduced into the target vessel over a 0.014-inch guidewire and is correctly placed across the target
stenosis using balloon marker bands as visual guides. As the acoustic shockwaves are propagated through
fluid and are impaired by air, the following step, essential to endure optimal transmission of the sonic wave,
is to clear the air out of the catheter. Then, the balloon can be inflated up to 4 atm to obtain the correct
apposition to the vessel wall. By pushing a button on the connector cable, the lithotripsy emitters are
activated, and after a cycle of 10 pulses, the balloon can be inflated up to 6 atm (reference pressure) in order
to increase balloon compliance and to check the symmetrical expansion that confirms calcium
modification. A minimum of two IVL cycles are recommended to treat the target stenosis (max 80 pulses).