Recent Advances in Percutaneous Cardioscopy
Yasumi Uchida
0
0
Developmental History of Percutaneous Cardioscopy
1
) Japan Foundation for Cardiovascular Research
, 2-30-17, Narashinodai, Funabashi 274-0063,
Japan
Percutaneous cardioscopy, using high-resolution fiberoptic imaging, enables direct visualization of the cardiac interior, thereby enabling macroscopic pathological diagnosis. Percutaneous cardioscopy has demonstrated that the endocardial surface exhibits various colors characteristic of different heart diseases. This imaging modality can now be used for evaluation of the severity of myocardial ischemia, and staging of myocarditis. Myocardial blood flow recovery induced by vasodilating agents or percutaneous coronary interventions can be clearly visualized. Morphological and functional changes in the cardiac valves can also be evaluated. Cardioscope-guided endomyocardial biopsy enables pin-point biopsy of the diseased myocardium. Recently, dye-image cardioscopy and fluorescence cardioscopy were developed for evaluation of the subendocardial microcirculation. Cardioscope-guided intracardiac therapies such as myotomy, myectomy, valvulotomy, and transendocardial angiogenic and myogenic therapy have been trialed using animal models in anticipation of future clinical applications. Percutaneous cardioscopy has the potential to contribute to our understanding of heart disease, and to assist in guidance for intracardiac therapies.
-
Direct observation of changes in the beating heart was
previously beyond the scope of any available imaging
Intracardiac observation using a rigid cardioscope in
animals was performed by Allen et al. in 1922 [1] and by
Harken et al. in 1943 [2]. In 1956, Sakakibara et al. [3]
employed a rigid cardioscope to observe a septal defect
during open-heart surgery. They also observed aortic valves
using the same cardioscope in 1958 [4].
Difficulties in producing a thin endoscope that can safely
be introduced percutaneously into the cardiac chambers,
and equipment that can displace blood, meant that about
29 years elapsed before Uchida and his coworkers
successfully performed percutaneous cardioscopy in
patients [5, 6]. Although this new modality of diagnosis is
now performed routinely in a few selected institutions, it
has yet to be adopted on a global scale.
In 1975, a 9-F fiberscope was developed in collaboration
with Olympus Corporation, Tokyo. This cardioscope was
introduced through an 11-F hard-tipped guiding catheter
into a canine left ventricle, but was abandoned due to
marked damage to the endocardial surface. In 1976, a 10-F
balloon-tipped guiding catheter was developed. This
catheter allowed the passage of a 6-F fiberscope. However, this
cardioscope also had to be abandoned because the balloon
became frosty during use due to the temperature difference
between the saline used for balloon dilatation and the blood
in the ventricle. In the same year, a fiberscope was devised
with a balloon at its tip. This fiberscope had a central lumen
through which warmed saline at body temperature could be
infused to dilate the balloon. The balloon was pushed
against the endocardial surface to observe changes through
the dilated balloon. However, introduction of this
fiberscope into the left ventricle was very difficult because a
guide wire could not be used, and if used in combination
with a guiding catheter, a big catheter had to be used to
allow the fiberscope to pass through. This fiberscope was
not used clinically. In 1983, a 9-F balloon-guiding catheter
was devised in collaboration with Clinical Supply Company,
Gifu, Japan. When inflated with CO2, the balloon protruded
more distally than the shaft tip to form a dead space between
the target and the balloon, at the same time preventing
damage to the myocardium by the shaft tip. In combination
with a 5-F fiberscope, this balloon catheter enabled
percutaneous transluminal observation of the cardiac
chambers and valves (Fig. 1). This cardioscopy system is now
routinely used clinically for observation, not only of the
cardiac chambers and valves, but also of the great vessels
including the pulmonary arteries, caval veins, and aorta.
A cardioscopy system comprises a light source, 4.5-F
fiberscope, 9-F guiding balloon catheter, intensified chilled
coupled device (ICCD) camera, camera controller, DVD
recorder, and television monitor.
The fiberscope (AF 14, Olympus Corporation) is a 4.5-F
fiberscope containing 3,000 glass fibers for image guidance
and 300 glass fibers for light guidance. The fiberscope is
passed through a 9-F guiding balloon catheter (Clinical
Supply Company). The balloon is inflated with CO2. The
catheter has a Y connecter at the proximal end: one channel
for fiberscope insertion and another for saline flushing.
White balance of the cardioscope is adjusted using white
gauze that is immersed in saline solution as the white color
(Fig. 1) [710].
Cardioscopy Procedures
Usually, following coronary angiography and left
ventriculography, a guiding balloon catheter is intr (...truncated)