JIM Today 2018 - Saturday - page 8

JIM today
Issue 3 
 24 February 2018
Intravascular lithotripsy:
Hopes of improving vessel
compliance without vessel injury
ntravascular lithotripsy (IVL;
Shockwave Medical, USA) is a
technology that delivers pulsatile
sonic pressure waves that fracture
intravascular calcium that commonly
hampers vessel compliance hinder-
ing stent delivery, expansion and
apposition. Todd Brinton (Stanford
University, CA, USA), the physician
co-founder of Shockwave Medical,
spoke at JIM 2018 yesterday, deliver-
ing the latest on IVL trial data as well
as discussing future developments.
In conversation with
JIM Today
Dr Brinton described the technology’s
nascent years: “We first developed a
peripheral product for the SFA. Over
the last couple of years we have been
working on coronary calcification
– this was originally my primary in-
The technique is similar to that of
urological lithotripsy. However, the
Shockwave IVL system was developed
specifically for intravascular use. The
IVL system consists of an IV-pole
mountable generator, connection
cable, along with a catheter that
houses an array of emitters within an integrated
balloon. The IVL catheter is advanced to the lesion
in standard fashion on the physician’s choice of
guidewire, and a 3kV generator powers the IVL
catheter. When the emitters discharge it has the ef-
fect of vaporising the saline/contrast mixture within
the integrated balloon, causing high-amplitude
sonic pressure waves that exceed 50 atm to disrupt
adjacent calcium, both at its surface and in its
media due to the field effect of the pressure wave.
Each catheter emits a total of 80 pulses at a rate of
one pulse per second.
“We’ve studied many different types of pressure
wave frequencies and found this optimal window
for patients,” explained Dr Brinton. “It provides the
most significant large-amplitude pulses, which with
a recovery time minimises the impact of heat. In
contrast, this is the ‘opposite’ of ultrasound, in the
sense that IVL is high amplitude, low frequency,
rather than low amplitude, high frequency. This
is pure mechanical energy being converted to
disrupt and fracture the calcium.
“One of the common problems we have in
the coronaries with placing stents is that we
have hard pieces of calcium that don’t allow the
stent to expand. IVL allows us to truly alter vessel
compliance and maximise acute gain.”
The DISRUPT CAD 1, which completed last year,
trialled 60 patients with heavily
calcified coronary lesions using
IVL. A 31-patient sub-study of this
trial also investigated the mecha-
nism of IVL, demonstrating its
effects on stenting and its optimal
deployment using OCT. DISRUPT
CAD 2 is just beginning enrolment
of a further 120 patients in 15
centres from nine countries in Europe. In addition,
DISRUPT CAD 3, a global US IDE study, is in its final
planning stages.
The European Disrupt CAD II trial will include
de novo
lesion lengths of up to 32 mm, and
excludes CTO. Unlike CAD I, the follow-on study
will include patients undergoing dialysis, which, Dr
Brinton noted, was a significant addi-
tion. The study’s aim is to assess the
procedural efficacy and safety of IVL,
and includes angiographic core-lab as
well as an independent clinical events
committee adjudication in order to
evaluate procedure-related MACE and
issues such as slow flow, no reflow,
and the potential for perforation. “We
know that other technologies used for
calcification certainly have some chal-
lenges in this regard,” said Dr Brinton.
“For more complex problems we tend
to use more complex tools, and the
safety profile is not as favourable as
traditional PCI tools.
“Because IVL is encased in an
integrated balloon, it is used like a
balloon, which is optimal for safety.
Rotational and orbital atherectomy
are great tools for very calcified, high
grade, difficult to cross lesions. If you
can’t get traditional tools across then
rotational atherectomy is excellent.
However, it doesn’t address how to
get optimal radial acute gain. Often,
most people will use these tools to al-
low them to then use higher pressure
balloons and stents. Instead, the idea
of IVL is to allow for optimal stent im-
Dr Brinton concluded with a look
to further applications of the litho-
tripsy principle: “We have done our work in Disrupt
CAD I and are starting enrolment in Disrupt CAD
II. A second-generation device will be available in
Europe mid-year. This device is further optimised
for deliverability with a 10 percent reduction in
profile and greater flexibility, without compromis-
ing sonic output.
“We are in the midst of developing an embodi-
ment of the core technology for use in treatment
of calcified aortic valves. Its use is for transvalvular
aortic lithotripsy. We have demonstrated clinical
feasibility and are in the development of a truly
percutaneous transfemoral system. This approach
uses sonic pressure waves to fracture calcium on
the aortic leaflets and improve aortic leaflet mobil-
ity. That is a piece of the company’s vision, growing
the technology for other clinical applications.”
Innovative technologies 
“One of the common
problems we have in the
coronaries with placing stents
is that we have hard pieces of
calcium that don’t allow the
stent to expand.”
Todd Brinton
“We are in the midst of developing an
embodiment of the core technology for
use in treatment of calcified aortic valves.”
Todd Brinton
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