Charles T. Troy, email@example.com
BOUCHERVILLE, Quebec – Coronary angioplasty is performed a million times a year in the US
to help patients with clogged arteries relieve angina. A main component of the procedure
is a balloon.
Now, with the goal of improving balloon deployment, researchers
at the Industrial Materials Institute of the National Research Council of Canada
and at the Centre for Intelligent Machines at McGill University in Montreal have
investigated a technique that combines a deployment tester with an optical coherence
tomography system. Their approach holds the potential to greatly improve angioplasty.
They reported their work in the August 2010 online edition of
the Review of Scientific Instruments, which is published by the American Institute
The investigators integrated an intravascular optical coherence
tomography (IVOCT) probe into a computerized balloon deployment system to monitor
the inflation process. The minimally invasive instrument provides detailed cross-sectional
imaging of the artery wall. Thanks to the development of swept-source optical coherence
tomography, IVOCT has evolved rapidly in the past few years. Studies have shown
its clinical relevance for the diagnosis of atherosclerosis and for monitoring the
results of percutaneous coronary interventions.
Shown are cross-sectional images demonstrating how balloon inflation
in a three-layer phantom mimics a coronary artery. The images reveal various levels
of balloon inflation pressure: a) a partially folded balloon without pressure; b)
a partially inflated balloon; c) an inflated balloon; and d) an OCT probe rotating
withina balloon (no phantom). The red dot indicates where the light beam exits the
probe. Note: Imaging is performed with IR light, but visible light is coupled in
the system to ease identifying probe location. Courtesy of Guy Lamouche.
OCT enables imaging over a depth of a few millimeters in a tissue
or material. By performing a custom pullback – rotation and translation –
of a catheter OCT probe in a balloon, the scientists can obtain precise measurement
of the diameter and thickness of entire balloons. The diameter can be estimated
by an external camera or a laser scanner, and the burst pressure can be characterized
by a balloon deployment tester.
“Balloon rupture has been reported in different articles,”
said Guy Lamouche, a research officer at the National Research Council of Canada.
“Although it does not occur frequently, the outcome can be fatal. We haven’t
identified any major problem in the current angioplasty balloons. Nevertheless,
the manufacturing process and testing of this product are continuously being improved,
and we propose an apparatus to ease the development process and to ensure optimal
The researchers used the LMS-100, a laser measurement system from
Interface Catheter Solutions of Laguna Niguel, Calif., and the LSM-9506, a laser
scan micrometer from Mitutoyo, for characterization of compliance, burst pressure
and the diameter of the balloon inflated in air. The system readings contained errors
when the balloons were inflated in water. A hydraulic pressure tester, the HP-3070,
also from Interface Catheter Solutions, performed leak, burst, compliance, fatigue
and cycle life testing.
The IVOCT probe comprises a single-mode fiber enclosed within
a spiral metallic tube in the proximal region and within a polymer tube in the distal
region. At its tip, light is focused by a gradient index lens and redirected at
90° by a right-angle prism. The optical components are enclosed in a metallic
“Combining OCT with a balloon deployment system provides
an improved platform for angioplasty balloon development and can also be used in
the development of next-generation minimally invasive devices for percutaneous –
through the skin – coronary interventions,” Lamouche said.
“It’s now possible to monitor balloon inflation within
an artery phantom (model) or an excised artery to assess the efficiency of innovative
balloon angioplasty or stent deployment procedures.”