Download Enhancing Vascular Imaging by OCT at the Charité Hospital

Enhancing Vascular Imaging by
OCT at the Charité Hospital
Based on an interview with PD Dr Bernhard Witzenbichler of the Charité Hospital (Berlin, Germany)
Professor Witzenbichler studied medicine in Munich and Düsseldorf, Germany, then completed
a 3-year residency in Boston, MA, USA. He joined the Charité Hospital Campus Benjamin Franklin
in 1998, performing coronary diagnosis and – from 2001 – interventional procedures.
Charité Hospital Campus Benjamin Franklin has four catheterization laboratories staffed by five
senior interventionalists and four fellows. Professor Witzenbichler performs approximately 1000 catheterization
operations annually, including approximately 600 of the 1600 interventional procedures conducted
at the hospital each year, encompassing coronary, renal artery and other interventions.
A powerful imaging modality matures
Optical coherence tomography (OCT) was first demonstrated
in 1991 for imaging the retina. OCT provides cross-sectional
images of blood vessel morphology by analyzing the interference
patterns of near-infrared light refracted from the tissue. The
micrometer-scale resolution of OCT is 10-times higher than
that of intravascular ultrasound (IVUS), an established modality
used to image blood vessel tissues.
Until recently, the application of OCT in coronary catheter
procedures was limited by the requirement to occlude the
coronary artery for about 60 seconds while imaging took
place, causing pain and increasing risk to the
patient. The new-generation LightLab
C7-XR™ OCT system marks a radical
improvement because it “provides
very fast pullback; within 3 or 4 seconds
you have a pullback length of 55 mm in
the coronary artery, without blocking
the artery”.
During OCT imaging, contrast
medium (used in angiography) is
injected into the vessel to ‘clear the
blood’ and provide an uninterrupted
imaging signal.
Precise control of contrast flow-rate
using the AngioTouch® Hand Controller
All quotes are taken from the interview with Professor Bernhard Witzenbichler
Bracco Group
Interpretation of OCT results during a cardiac catheterization
laboratory procedure
To achieve consistent blood clearance, the CVi system
allows the interventionalist to precisely control contrast
injection, using the ergonomic AngioTouch® Hand Controller,
at the same time as manipulating angiographic catheters.
“Without using the CVi system, I’m convinced that it would not
be possible to get the same quality and (even more importantly)
I think it wouldn’t be so reproducible”.
Clinical applications of OCT
Professor Witzenbichler began using OCT as part of a clinical
study of treatments for acute myocardial infarction, designed
to assess the correct positioning (apposition) of self-expanding
and conventional stents. OCT is considered uniquely powerful
as a tool: To determine the behavior or apposition of stents
during procedures or follow-up, and to image the coverage
of the stent struts with neointimal tissue. Specific applications
may include follow-up assessment of drug-eluting stents or
bio-absorbable stents and assessing apposition during the
placement of multiple stents. OCT “enables you to see the tissue
coverage on the stents, so in terms of the healing processes you get an
idea of what’s going on”. Visualization is “not as good with IVUS because
the resolution is not good enough – you see the struts but they look much,
much thicker”. With OCT “very often you see a visible thrombus or
plaque prolapse... which you wouldn’t see angiographically... and which
you probably wouldn’t see using IVUS after stent placement”. Correlating
the appearance of these pathologies during surgery or at
follow-up with outcomes data may provide guidance for future
therapeutic procedures.
Visualization of a stent in a coronary artery using the LightLab C7-XR™
OCT system
During interventions, precise control of the contrast flow rate is
advantageous to ensure that imaging occurs exactly when it is
most useful for the interventionalist. In addition, low flow rates
Broader applications of the ACIST variable flow-rate
contrast delivery system
are important to prevent stents from becoming dislodged during
The ACIST variable flow-rate contrast delivery system was
first tested at the Charité Hospital in 2003, and was quickly
adopted in their catheterization laboratories for mainstay
procedures such as diagnostic angiography.
(damage to the vessel wall), both of which can be caused
The system allows real-time monitoring of contrast medium
volume used during each imaging procedure. Contrast
dosing is limited due to mild nephrotoxicity associated with
the contrast agent, and must therefore be limited, especially
in certain patient groups such as those with renal impairment.
“With the ACIST machine it’s very convenient... at any time you
have an overview of how much contrast you used”. Compared
with manual or power injection, the system can reduce the
volume of contrast agent used during a given procedure by
approximately 30%, resulting in significant cost savings.1
both of which are not available with manual injection systems.
placement and to avoid rare complications such as ‘deflection’
by an undesirably strong injection of contrast agent. Further
safeguards to the patient result from the on-board automatic
pressure monitoring system and the detection of air bubbles,
In the past, after conducting several procedures per day
using conventional manual injection, some interventional
cardiologists had been left with pain or soreness in their hands.
The ACIST AngioTouch® Hand Controller has resolved the issue
of hand stress at the Charité Hospital.“Within the last 10 or 20 years
there were a lot of inventions for the benefit of the patient, I think
this is one where it’s for the benefit of interventionalists!”
The future of OCT
OCT and IVUS will likely continue to be used in parallel for different applications. IVUS will be used prior to interventional
treatment, to plan procedures and define the position of plaque and healthy tissue, because it provides important information
about vessel wall composition. Alternatively, OCT is likely to be utilized during interventional procedures or at follow-up, to
assess stent apposition, monitor the healing process and identify pathology that indicates potential risk.
As OCT is a new technology, there is no standardized protocol for how to analyze the imaging output. Some cardiologists
see this as an opportunity for research and publication. If a large clinical trial (perhaps in >10,000 cases) was able to
demonstrate a clinical advantage in terms of patient survival rates; for example, preventing stent thrombosis it would
promote interest in OCT technology outside of research hospitals.
To learn more about ACIST contrast delivery technologies contact us
1-888-667-6648. www.acist.com
© 2010 ACIST Medical Systems. All rights reserved. P/N 610.299.01_US
1. Brosh D, et al. Int J Cardiovasc Intervent 2005;7(4):183–7.