2. Intravascular ultrasound (IVUS) is a medical imaging methodology using a
specially designed catheter with a miniaturized ultrasound probe attached to
the distal end of the catheter.
The proximal end of the catheter is attached to computerized ultrasound
equipment.
It allows the application of ultrasound technology to see from inside blood
vessels out through the surrounding blood column, visualizing the endothelium
(inner wall) of blood vessels in living individuals.
3. IVUS uses echocardiography : Very high frequency sound waves, called
ultrasound, are emitted by a transducer.
These ultrasound waves, which are beyond the range of human hearing,
bounce off the various types of tissue structures in the body and the echo of
these waves is then converted into a picture.
4. Physics and equipment
IVUS systems contain a special transducer mounted catheter and an electronics
console to reconstruct the image. The ultrasound signal is produced in the
transducer by passing an electrical current through the piezoelectric (pressure-
electric) crystalline material (usually ceramic) that expands and contracts when
electrically excited.
After reflection from tissue, part of the ultrasound energy returns to the
transducer and is converted into the image. High ultrasound frequencies (20–
40 MHz) are employed resulting in an axial resolution in the range of 80–
150 μm and lateral resolution of 200–250 μm.
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10. PRE-INTERVENTION
Accurate quantitation
Assessment of reference segment disease
Interventional strategy & device selection
In-stent restenosis
Plaque composition
Length of lesion
15. Contraindication for IVUS guidance,
small vessels,
tortuous vessels and
degenerated vein grafts.
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17. A very small skin incision is made at the site. A sheath is first inserted into an artery or vein
(usually in the groin). Using x-ray or ultrasound guidance, the catheter is inserted into the
sheath and gently maneuvered through the vessel to the target location over a very thin, soft
wire.
Once in place, the transducer on the end of the catheter uses sound waves to produce pictures
of the blood vessels.we can move the catheter to obtain images of the inside of the vessels at
different locations. At the end of the procedure, the catheter will be removed and pressure will
be applied to stop any bleeding. The opening in the skin is then covered with a dressing. No
sutures are needed.
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23. IVUS has many benefits including:
showing the presence and amount of plaque in arteries measuring the degree to which
the vessel has become narrowed from plaque
providing information about what the plaque is made of
detection of restenosis
more accurate stent placement and
reduced incidence of stent thrombosis in arteries and veins
finding stenosis or narrowing which is not well seen with angiography
finding areas of vein external compression, which may be predisposed to blood clots
no exposure to ionizing radiation
24. Any procedure that involves placement of a catheter inside a
blood vessel carries certain risks. These risks include
damage to the blood vessel, bruising or bleeding at the puncture site, and
infection. However precaution is taken to mitigate these risks.
Other risks may include:
irregular heart rhythms (arrhythmia)
a blood clot
an allergic reaction to the medications used during the procedure
very rare cases, a heart attack, stroke, or blood clot in the lung
IVUS itself adds little additional risk to angioplasty and catheter angiography
25. Because of the catheter's size and stiffness, IVUS sometimes cannot be
navigated through very narrowed or twisted blood vessels.
The technology sometimes produces image artifacts.
There is conflicting information regarding the ability of IVUS to characterize
high-risk plaques and thrombus.
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28. How to determine lesion length morphology
How to identify dissections
Determining appropriate stent placement
Determining lesion size
Understanding the shortfalls of angiography
the adventitia -- the outer covering of the artery;
the media -- the actual wall of the artery;
the intima -- a layer of endothelial and other cells that make direct contact with the blood inside the artery -- in normal arteries this layer is thin; in diseased arteries (shown here) the intima is thickened by plaques or other tissue growth, often eccentric or asymmetrical;
the lumen -- the actual open channel of the artery through which the blood flows.
In angiography, angle of view determines what we see
As LMCA lesions are short, often calcified and diffuse involving the ostium or bifurcation, IVUS plays a pivotal role in assessing the significance of these lesions, which are notoriously difficult to accurately assess with angiography alone.
RATIO OF DISTAL MEAN CORONARY PR. TO MEAN AORTIC PRESSURE IN THE STENOTIC VESL DURING MAX. HYPEREMIA
REPRESENTS THE FRACTION OF BLOOD FLOW PRESERVED DESPITE STENOSIS .N:>0.8;SIGNIFICANT:<0.75
Because of the catheter's size and stiffness
The IVUS catheter is a thin, flexible tube with a tiny ultrasonic transducer attached to one end. The other end of the catheter connects to a computer workstation that converts the sound waves from the transducer into real-time images on a monitor. Different size catheters are available depending on the type of blood vessel being imaged.