The Cath Lab of the Future
Interventional cardiology thought leaders
share their views on what the future holds
By:Dave Fornell
June 17, 2014
Interventional thought leaders at the American
College of Cardiology (ACC) 2014 meeting shared their predictions about the
cutting-edge technologies emerging today that will become commonplace in the
cath lab of the future.
“Innovation in medical technology is key to the
advancement of medicine,” said Martin Leon, M.D., director, Center for
Interventional Vascular Therapy, Columbia University Medical Center/New
York-Presbyterian Hospital, New York. He noted mortality from myocardial
infarction (MI) has dropped dramatically — by 80 percent since the 1950s — due
to technological advancements. He said the next generation of advances will
improve operator performance, enable more complex procedures, change the
reimbursement system, improve patient and operator safety, and expand the use
of minimally invasive cardiovascular procedures into new areas that were
previously only the domain of surgeons.
Heart Failure Interventions
Leon said several new technologies will soon enable
interventional heart failure care. One of the biggest advances in technology,
he said, is the CardioMEMS implantable heart failure monitor, which was cleared
by the U.S. Food and Drug Administration (FDA) in May. The device is inserted
into the pulmonary artery via a transcatheter procedure and accurately monitors
pressure to detect fluid retention due to worsening congestive heart failure
symptoms. It can detect changes prior to a patient needing hospitalization,
when they can be treated with medication, which is hoped to reduce the massive
numbers of heart failure readmission rates.
Smaller, fully implantable ventricular assist devices
(VADs) will soon be used to help offload the heart to help it heal and put the
patient on the road to recovery, rather than the usual downward slope of progressive
heart failure. Leon cited the CircuLite micro VAD, about the size of an AA
battery, which can be implanted in a minimally invasive procedure via the
subclavian artery. It is designed for long-term support of less sick,
ambulatory, chronic heart failure patients who are not yet inotrope-dependent.
Another transcatheter technology being developed for
heart failure is the intra-arterial shunt device (IASD) by DC Devices. Leon
said the permanent heart implant represents a new way to treat diastolic heart failure
by relieving blood pressure on the left side of the heart and redistributing it
to the right side. It takes about 15 minutes to implant the device and is hoped
to help reduce readmission rates and eliminate surgical costs.
New Interventional Therapies
With declining coronary procedure volumes and many new
interventional technologies on the horizon, Leon predicts 50 percent of the
financial return from cardiac cath labs will be from non-coronary procedures by
2020. These will include transcatheter valve repairs or replacements (TAVR),
left atrial appendage (LAA) occluder placements to eliminate the need for
warfarin in atrial fibrillation (AF) patients, peripheral artery disease (PAD)
interventions and procedures to correct congenital heart defects.
In regards to coronary stenting, which had been the bread
and butter of the coronary cath lab, Leon predicts in the future that 50
percent of patients will receive a bioresorbable stent as the technology begins
to replace permanent metallic stents.
Appropriate Use Criteria
As healthcare reform continues to move forward and
physicians increasingly rely on evidence-based medicine, medical societies are
developing appropriate use criteria (AUC) for all tests, procedures and disease
states. Leon said in the future, following AUC will become part of
reimbursement. In fact, during ACC.14, Congress passed a new Medicare bill that
now requires use of clinical decision support for AUC to document justification
of expenses charged to Medicare.
In the cath lab, Leon said bread-and-butter stenting
procedures may need justification using fractional flow reserve (FFR) data to
show a lesion being treated is flow-limiting. He said that for this reason, it
will be important that FFR data is captured and recorded in the patient
record.
Leon said it is very possible the use of invasive
catheter-based FFR in the cath lab might be replaced in the next few years with
noninvasive computed tomography FFR (CT-FFR). The CT technology, already in
trials, can track the flow of blood through the coronaries to determine FFR
pressures for the entire coronary tree. The software also enables virtual
stenting to recalculate the flow to see which lesions need to be treated prior
to taking a patient to the cath lab.
Advanced Imaging, Guidance, Planning
New imaging techniques will enter standard practice in
the cath lab to enable advanced 3-D imaging to facilitate more accurate
navigation inside vessels and device placement, Leon said. “This technology is
already here and is used today,” he noted.
Most modern angiography systems offer rotational 3-D
angiography, which uses a quick spin around the patient to create a CT-like 3-D
image of the anatomy, which can all be done tableside in the cath lab. Some
systems allow these or CT or MRI (magnetic resonance imaging) 3-D images to be
overlaid or fused with the live 2-D fluoroscopic images. This fusion technology
is used with TAVR planning and navigation software to better guide precise
device placement of procedures, Leon said.
The next step in advanced visualization will be the use
of free-floating, 3-D holographic images in the cath lab. Leon said this
technology, developed by RealView, is already being used in the prototype stage
in a handful of cath labs. It allows physicians to interact with the 3-D
datasets, rotating them and even being able to slice through the image on any
plane to see cross sections.
Cardiology IT
Information technology in the near future will go far
beyond reporting and PACS (picture archiving and communications systems), Leon
said. “There is a collision of medical technology and health IT that will
produce a unique blend of new technologies,” Leon said.
There is rapid proliferation of tiny and inexpensive
patient monitoring devices that will bring new patient monitoring data into
patient’s electronic medical records (EMRs). These will be used to better
monitor diabetes, heart failure, hypertension and arrhythmias.
Current technology allows 3-D images to be printed by
special printers as resin 3-D models. Leon said this technology is now being
experimented with, using bio-materials to print custom-made implantable
devices, such as heart valves.
Enhanced Intravascular Imaging, FFR
There have been numerous advances in cath lab imaging
system, including technologies on the horizon that may fundamentally change how
patients are treated, said Gary Mintz, M.D., Transcatheter Cardiovascular
Therapeutics (TCT) co-director and chief medical officer, Cardiovascular
Research Foundation (CRF).
While FFR has the ability to identify which lesions are
causing ischemia and the modality is recommended to show the need for stenting
a patient, FFR requires the use of adenosine. Mintz said a new non-adenosine
method called iFR (instantaneous wave-free ratio) was recently validated with a
close 90 percent correlation with FFR. He said this will make FFR faster and
easier to use, and limit the need for adenosine to only about 30 percent of
patients.
Leon said noninvasive CT-FFR from CT scans will likely
replace the need for invasive wire-based FFR in the coming years.
The intravascular infrared spectroscopy developed by
Infraredx has the ability to identify lipid core plaques based on the chemical
makeup of the lesion. It is combined with intravascular ultrasound (IVUS) to
show the anatomy of the vessel segment. Mintz said the technology is currently
being tested in a trial to pre-emptively identify vulnerable plaques, which are
suspected as the primary culprits in acute myocardial infarctions. If the trial
proves the technology can accurately identify dangerous, at-risk lesions prior
to heart attacks, it may serve as a detection device to preventively treat
these lesions to prevent future heart attacks.
Mass General Hospital is developing a combined optical
coherence tomography (OCT) near-infrared (NIR) spectroscopy intravascular
imaging system. Mintz said this system is similar to the Infraredx technology,
but will offer more detail with its high-resolution OCT imaging of the anatomy.
There are pros and cons with both IVUS and OCT, so a
hybrid combined OCT/IVUS imaging catheter is in development and has already
been used in animal studies, Mintz said. OCT has a resolution of about 10
microns, while IVUS is about 100 microns.
The coming advancement of micro-OCT, now in development,
offers resolutions of less than 1-2 microns. Mintz said this would allow easy
imaging of individual stent struts and the ability to clearly see tissue
coverage.
A recently introduced OCT advancement from St. Jude
Medical allows 3-D reconstructions of OCT image datasets. The technology allows
a 3-D image of the interor of vessels to be created and presented in a
cut-plane view to better identify side branch vessels and to visualize stent
malapposition and tissue coverage. Mintz said 3-D OCT might be able to help
reduce the need for FFR in many patients because the physician will be able to
clearly see issues inside the vessel.
Mintz said there is a high-resolution IVUS system in
development that will be downsized into a console that looks like a large iPad
device. It will enable fast pullbacks, similar to those used for OCT.
There are already some examples of fusion imaging that
co-register CT images with live angiography to improve procedural guidance by
showing both the vessel lumen, the radio-opaque markets of the catheters and
the surrounding anatomy. Key examples of this are fusion software packages
available for TAVR planning and procedural navigation. He said this type of
fusion imaging will become much more commonplace in the future and will prove
very helpful to steer wires and devices through or around chronic total
occlusions (CTOs).
Another type of fusion imaging is co-registered IVUS and
angiography. Mintz said this is now offered via the MediGuide system from St.
Jude Medical, which displays the position and orientation of devices equipped
with a tiny sensor on both live and prerecorded fluoroscopy in real time. Other
examples of this type of co-registration for IVUS and angiography were recently
released by Volcano and Siemens Healthcare.
Holographic Navigation
Today’s cath lab makes regular use of 3-D technology,
including rotation angiography, TEE (transesophageal echo), CT and MRI
reconstructions, EP (electrophysiology) lab navigation systems, and structural
heart procedure 3-D fusion imaging systems. However, Elchanan Bruckheimer,
MBBS, director of the cardiac cath lab, Schneider Children's Medical Center,
Israel, said none of these are true 3-D, because they are still viewed on 2-D
display screens. “The problem is not the people using the system, it’s the fact
that the image data is trapped in the screen,” he explained.
He said this may soon change with the introduction of
free-floating holographic imaging, which will allow image projections in the
cath lab above the patient where the image can be rotated or sliced through on
any axis. He said there has been a prototype system from RealView at his cath
lab to display complex cardiac anatomy in holograms. He showed examples of ASD
(atrial septal defect) procedures where 3-D TEE holographic images where used
for procedural navigation to close the hole using an Amplatzer device. He said
the holograms could be rotated to any angle to ensure proper device placement
prior to final release of the device and recently completed five procedures
using this type of imaging.
He showed examples of how the cardiac anatomy can be
segmented using the RealView system, stripping an image of a heart down to the
left atrium. He then showed how marks can easily be made on the hologram to
show where catheter manipulations are needed for a pulmonary vein isolation. In
the future, he said the coordinates of these marks might be transferred into a
Hansen robotic EP navigation system to help automate the ablation catheter
manipulation to these points.
He said RealView expects to have an operational
cart-based holographic system available by 2015.
Robotic PCI
There are now robotic systems available for peripheral,
coronary and electrophysiology procedures. Users say these system greatly
improve their accuracy in vessel navigation and procedural precision, even
among experienced well-known operators.
“Why do we need robotics? We need it to improve
procedural success, patient safety and operator safety,” said Giora Weisz,
M.D., Shaare Zedek Medical Center, Jeruselum, Israel. He shared his experience
using the Corindus CorPath system for percutaneous coronary interventions
(PCI).
Despite how experienced an operator may be, they still
have limited control of interventional devices within the body. He said this
frequently translates into geographic misses with stent coverage which can
contribute to adverse events. Geographic misses also contribute to the 13-32
percent of cases where a second stent is needed.
Weisz was involved in the FDA pivotal trial, where there
were zero complications and a 99 percent procedural success rate without the
need to convert to a manual procedure, which was the trial’s primary endpoint.
He said overall the trial data showed the robotic system helped reduce
procedural time and increase accuracy when navigating devices inside
vessels.
The operator uses joystick controls to navigate vessels
on a screen in front of them while seated in a lead-lined cockpit. There is a
robotoc catheter drive unit attached to the patient table that utilizes a
single-use cassette that enables any off the shelf devices to be used.
“Intravascular manipulation of devices is easy and
intuitive using the system,” Weisz said. The FDA approval study only looked at
use of the CorPath in straightforward easy PCI cases, but he said in an ongoing
post-market study, the system is being used in more complex cases.
During traditional procedures, interventional
cardiologists are exposed to radiation and need to wear heavy lead aprons. The
excessive weight causes fatigue and about 70 percent reported they now have
serious back problems in a Society of Cardiovascular Angiography and
Interventions (SCAI) survey. From a dose perspective, Weisz cath lab staff
receive an average of about 20.6 mGy of dose per procedure, but with the
CorPath system operator’s booth, that level was reduced 95 percent to just 0.98
mGy.
Radiation Reduction
Leon said ionizing radiation from medical imaging has
become a growing concern among the public and medical community, but new
technologies can help reduce dose. Cardiac imaging accounts for about one-third
of the source of radiation dose from medical imaging. In the cath lab, as
transcatheter procedures become more complex and require longer imaging times,
radiation exposure to both patients and operators is increasing.
“We are working pretty much the same way in labs today or
the as we did more than 30 years ago,” said James Goldstein, M.D., director of
research and education, cardiovascular division, William Beaumont Hospital.
This means safety has not improved much, as operators still wear heavy lead
aprons which cause long-term back and spine issues, and radiation exposure to
the eyes causes a high rate of cataracts. He cited studies showing 60 percent
of interventional cardiologists have spine issues and 51 percent have the
beginnings of cataracts.
“The badges don’t protect us, and about 50 percent of
interventional cardiologists don’t wear their badges anyways, because they
don’t want to get pulled out of the lab,” Goldstein said.
He made the analogy to the NFL ignoring concussion issues
for years and knowing concussions had long-term effects on the lives of
football players, but doing nothing about it. “We go into the cath lab today
dressed like football players in the 1950s with leather helmets and no
faceguards or other protection,” he said.
However, he said new technology is available to address
radiation and taking the cath lab staff and the operator out of the radiation
field by using robotic systems from Stereotaxis, Hansen and Corindus. There are
also new radiation protection systems available to help block radiation
scatter. These include the RadPad and Trinity radiation protection systems, and
the ZeroGravity ceiling gantry mounted lead suit system that takes the weight
of lead aprons off of physicians.
Newer, large format displays now available for cath labs
enable a larger field of view and better visualization of the anatomy, instead
of leaning over the table to try to see anatomic details on smaller screens,
said John Messenger, M.D., FACC, director, cath labs, University of Colorado.
This helps better visualize procedures and helps lower dose by not needing to
image the anatomy several times.
He said all the major vendors recently released newer
angiography systems with dose lowering technologies, including new X-ray tubes,
and more sensitive detectors and software to help improve image quality at
lower doses, including noise reduction. He pointed to the Philips Allura
Clarity as an example of the next-generation angiography system, which can
lower standard procedural dose by 50 to 75 percent. He said the operator
can easily adjust the frame rates to help reduce dose.
The University of Colorado is using a new Allura Clarity
system, and when comparing it to older Philips Xper systems, they found an
average reduction of 750 mGy with a more than 50 percent reduction in dose.
“These are very striking reductions in dose,” Messenger said.
Messenger said Toshiba’s Spot Fluoroscopy software for
its Infinix-i systems allows clinicians to observe a target region of anatomy
using Spot Fluoro’s live fluoroscopy, while viewing the last image hold (LIH)
in the surrounding area that has been collimated out of the field of view to
cut dose.
He said the Mayo Clinic began a program to lower its
radiation dose through best practices. It began use of the dual-axis rotational
coronary angiography (DARCA) technique, which uses a rotation of the gantry
around the patient with simultaneous left to right and craniocaudal movements.
This allows complete imaging of the left or right coronary tree with a single
acquisition run. The technique helped lower both contrast and imaging dose, and
helped achieve a 50 percent dose reduction in radial access procedures.
MRI Could Replace Angiography
Ionizing radiation could be completely eliminated from
the cath lab if the angiography system is replaced by MRI image guidance. The
cath lab at the National Institutes of Health (NIH) has one lab that uses MRI
instead of X-ray angiography to visualize procedures inside patients. The
advantage of MRI is that it can visualize all the patient’s anatomy, not just
an X-ray of unblocked coronary artery lumens. Another advantage is that MRI
does not use radiation to image, so it is safe for patients during longer
procedures and the physician can use live imaging during the entire procedure.
Additionally, cath lab staff and operators do not need to wear lead.
“We don’t have to wear lead, but we do have to wear
headsets to be able to speak to each other over the annoying noise of the MRI
system,” explained Robert Lederman, M.D., from the NIH cath lab. “All you need
for this is an experienced cardiovascular MRI tech to help with the imaging.”
MRI shows all of the soft tissue anatomy in the field of
view, including chambers of the heart and blood flow, which can help visualize
clots or pulmonary embolisms. “One of the great things about MRI is that
you can see where your catheters are going,” he said.
NIH has designed a guidewire with a tip that serves as an
MRI receiver. The tip lights up in bright fluorescent green on the MRI to
clearly see where it is in the anatomy. Lederman said this has been very
helpful for procedures such as transseptal punctures. “Under MRI the procedures
are very relaxed and controlled, because you can see what you are doing and
what tissue your needle is going through,” he explained.
Transcatheter closure of PFOs and other holes in the
cardiac septum is usually assisted under angiography with TEE. Under MRI,
Lederman said adjunct imaging is not needed, because the operator can clearly
see the hole, the septum, chambers and the device all at once.
The NIH worked with Children's National Medical Center in
Washington, D.C., to create the first pediatric MRI cath lab in the country,
which is opening in 2014.
