Press backgrounder
Philips VesselNavigator in the repair of abdominal aortic aneurysms
VesselNavigator, Philips’ latest image-guidance tool for Vascular Suites and Hybrid OR Suites
(operating rooms suitable for both open surgery and minimally-invasive surgery), is a real-time
3D navigation solution that allows interventional radiologists and vascular surgeons to perform a
wide range of endovascular procedures.
These procedures, which reduce the need for open surgery, typically involve passing a catheter
through major arteries or veins in order to position and deploy therapeutic implants such as
stents. However, because interventional radiologists and vascular surgeons performing these
procedures cannot physically see or touch the blood vessels they are trying to repair, they
require sophisticated real-time image guidance tools to assist in catheter guidance and implant
placement. VesselNavigator combines real-time X-ray imaging (X-ray fluoroscopy) data with preacquired diagnostic CTA (computed tomography angiography) or MRA (magnetic resonance
angiography) images to provide the necessary 3D guidance.
Abdominal aortic aneurysm repair
Endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms is one commonly
performed procedure where VesselNavigator offers benefits. An abdominal aortic aneurysm
(AAA) is a ballooning of the abdominal aorta that can rupture without warning (typically being
asymptomatic), resulting in massive internal bleeding and death unless patients are operated on
quickly. Around 8 out of 10 people with a ruptured aortic aneurysm either die before they reach
hospital or don’t survive surgery. AAAs are sufficiently common (occurring in 1.3% to 8.9% of
men and 1.0% to 2.2% of women over 60 years of age1) that some countries have recently
initiated ultrasound screening programs to identify them. As a result, the number of EVAR
procedures being carried out to repair AAAs before they rupture is increasing (CAGR 10%).
AAAs were originally repaired via open surgery, during which the patient’s abdomen is opened
up and a tubular stent-graft is manually stitched in place to reinforce the affected section of
aorta. Although this treatment has a high success rate (93% to 97% of patients achieve a full
recovery), the downside is that it imposes significant trauma on the patient, resulting in longer
hospitalizations and extended recovery times. Today, an increasing number of AAAs are being
treated using EVAR procedures to insert the stent-graft. These minimally-invasive procedures
not only impose less trauma on the patient, resulting in faster patient recovery, they also offer a
solution for patients who are considered too frail to survive open surgery.
Stent-graft placement needs to be performed with precision, especially if the stent has
apertures in it to allow blood to flow from the repaired aorta into artery side branches such as
those that feed the patient’s kidneys or diaphragm. These ‘fenestrated’ stent-grafts are often
custom made to match a patient’s unique anatomy. Placing them in a so-called FEVAR
(fenestrated endovascular aneurysm repair) is particularly challenging due to the need to both
vertically and rotationally align the apertures in the stent with the appropriate artery side
branches.
Risk of renal failure
Courtesy of Dr. J. van Herwaarden
Up until now, vascular surgeons or interventional
radiologists performing EVAR or FEVAR procedures
typically needed to capture various views of the patient’s
abdominal arteries (2D X-ray fluoroscopy images from
different angles) during the procedure in order to
achieve correct stent placement. However, the radioopaque contrast agent that needs to be injected into the
blood to image the arteries is toxic to the kidneys, so one
of the risks associated with complex EVAR and FEVAR
procedures is a type of acute renal failure called contrastinduced nephropathy. Impaired initial renal function is
therefore one of the criteria that often excludes patients
from having these procedures.
Reducing risk, increasing accuracy
Philip’s VesselNavigator software significantly
reduces the need for repeated real-time
imaging during the procedure, and hence the
risk of contrast-induced nephropathy or longterm kidney damage, by fusing pre-operatively
acquired CTA or MRA images with a single X-ray
fluoroscopy image acquired at the beginning of
the procedure. Once vascular surgeons or
interventional radiologists have correctly
registered these images (typically through the
use of ‘landmarks’ in the image, such as the
Courtesy of Prof. Dr. Schermerhorn, Boston, USA
patient’s pelvis) the 3D information contained in the CTA or MRA images allows them to view
the patient’s abdominal vasculature from any angle, without the need to shoot additional X-ray
images for that purpose. It is this ability to view the vasculature in 3D that helps to achieve the
necessary accuracy in stent placement.
Over-exposure to contrast medium used to visualize the arteries with X-ray imaging during the
procedure can damage the kidneys. With a growing population of elderly and diabetic people
who suffer from poor kidney function, reducing contrast medium requirements significantly
benefit the patient population. In clinical studies carried out at the University Hospital Cologne,
Germany, and the University Hospital Ghent, Belgium, the use of VesselNavigator has been
shown to reduce contrast medium usage by 70%2 and procedure times by 18%3 – leading to
safer, more efficient and more cost effective treatment of vascular conditions.
VesselNavigator joins Philips’ extensive portfolio of live, 3D image-guided navigation solutions
for minimally invasive procedures. This portfolio also includes HeartNavigator and
EchoNavigator for structural heart disease repairs, EP Navigator for cardiac electrophysiology
interventions, and EmboGuide to support tumor embolization in cancer treatment.
1
Irwin RS and Rippe JM (2008). Irwin and Rippe's Intensive Care Medicine, Lippincott Williams & Wilkins,
ISBN: 978-0-7817-9153-3, page 385.
2
Tacher V, et al (2013). Image Guidance for Endovascular Repair of Complex Aortic Aneurysms:
Comparison of Two-dimensional and Three-dimensional Angiography and Image Fusion, J Vasc Interv
Radiol, 24(11), 1698-1706.
3
Sailer AM, et al (2014). CTA with fluoroscopy image fusion guidance in endovascular complex aortic
aneurysm repair, Eur J Vasc Endovasc Surg. 2014 Apr;47(4):349-56.