Call Girls Siliguri Just Call 9907093804 Top Class Call Girl Service Available
Ivus
1. Intravascular Ultrasonography
(IVUS)
PROFESSOR F. RAHMAN
MBBS (Dhaka), MCPS (Med), D-Card (DU), MD (Card)
FACC (USA), Fellow-in Interventional Cardiology (USA)
Professor (Interventional Cardiology)
Department of Cardiology, UCC
Bangabandhu Sheikh Mujib Medical University.
2. Introduction
• Intravascular ultrasonography is an invasive
imaging procedure that provides intravascular
images of the coronary arteries (and other blood
vessels).
• IVUS has played a critical role in-
– coronary atherosclerosis pathophysiology
– diagnostic and therapeutic strategies for various
vascular pathologies.
– integral role in the evolution of interventional
cardiology.
4. Indications
• IVUS in PCI :
To plan interventional strategy & to optimize stent
deployment.
Find reference lumen dimensions and lesion
length for appropriate stent sizing;
Identification of superficial calcium by IVUS can
lead to pre-stent rotational atherectomy
5. IVUS in PCI :
Assess thrombus burden (Operators may
alter anticoagulant therapies or consider
mechanical thrombectomy).
Post-stent IVUS assessment may detect
complications of PCI and suboptimal stent
deployment.
6. Contraindications
• Intravascular ultrasonography in
interventional cardiology is an adjunct
procedure to coronary angiogram.
• As such, any contraindication to coronary
angiography applies to intravascular
ultrasonography as well.
11. Technical Considerations
• A miniature ultrasound-mounted catheter is
connected to an electronics console
• An electrical current is passed through the
piezoelectric (pressure-electric) crystalline material
of the transducer that expands and contracts when
electrically excited.
12. Technical Considerations
• After reflection from tissue, part of the ultrasound
energy returns to the transducer.
• The received signal is converted to electrical energy
and sent to an external signal processing system for
amplification, filtering, scan conversion, user-
controlled modification, and graphic presentation.
13. Technical Considerations
• The ultrasound beam upon reflection remains fairly
parallel for a distance (near field) and then begins to
diverge (far field).
• The quality of ultrasound images is greater in the
near field because the beam is narrower and more
parallel.
• Therefore, larger transducers with lower
frequencies are used for examination of large
vessels because they create a deeper near field.
14. IVUS Technique
• Prepare IVUS catheter
Flush with saline
Position imaging catheter across lesion
Place distal marker minimum 3 cm beyond the
region of interest
Set gain and field of view
Image acquisition
Manual
Automated pull back
19. Normal Arterial Appearance
• A standard intravascular ultrasound image consists
of three main components: catheter, lumen, and
arterial wall.
• An ultrasound reflection is generated at a tissue
interface if an abrupt change in acoustic impedance
occurs.
20. Normal Arterial Appearance
• In the normal artery, two such interfaces are usually
observed:
I. One at the border between blood and the leading edge of
the intima
II. Second at the external elastic membrane, which is
located at the media-adventitia border.
• In patients under 40 years of age, the reported normal
value for intimal thickness is typically between 0.15 mm
and 0.25 mm.
• Most investigators use 0.25 to 0.50 mm as the upper
limit of normal.
22. Border Identification
• Recognizing that all ultrasound techniques,
including intravascular ultrasonography, require
measurements to be performed at the leading edge
of boundaries, never the trailing edge, is important.
• In muscular arteries such as the coronary arteries,
frequently three layers exist.
23. Border identification
1. The innermost layer consists of a complex of intima and
internal elastic membrane.
I. This innermost layer is relatively echogenic compared with the
lumen and media.
II. The trailing edge of the intima (which would correspond to
the internal elasticmembrane) cannot always be
distinguished clearly.
2. Moving outward from the lumen, the second layer is the
media.
3. The third and outer layer consists of the adventitia and
periadventitial tissues. The boundary separating the true
adventitia from surrounding perivascular tissues is less well
defined on intravascular ultrasonography images.
24. Lumen Measurements
Lumen measurements are performed using the
interface between the lumen and the leading edge
of the intima.
Generally, the leading edge of the innermost
echogenic layer should be used as the lumen
boundary.
The following basic measurements can be recorded
depending upon the operator’s preference
25. Lumen Measurements
• Lumen cross sectional area (CSA): The area
bounded by the luminal border
Minimum lumen diameter: The shortest diameter through the center
point of the lumen
Maximum lumen diameter: The longest diameter through the center
point of the lumen
Lumen eccentricity: 1 [(Maximum lumen diameter – minimum lumen
diameter)/maximum lumen diameter]
Lumen area stenosis: (Reference lumen CSA – minimum lumen
CSA)/reference lumen CSA
26. Special Measurements
• Further special measurements facilitated by
intravascular ultrasonography are as follows:
External elastic membrane measurements
Atheroma measurements
Calcium measurements
Stent measurements (a post deployment minimal stent
area of 5 mm2 predicts increased likelihood of
angiographic restenosis)
Remodeling
Length measurements
28. Atheroma Morphology by IVUS:
Soft (left), mixed fibrous and calcified (center), and
heavily calcified atheromas (right) are illustrated.
29. Atheroma Morphology
• Although intravascular ultrasonography cannot
be used to detect and quantify specific histologic
contents, certain image patterns can be very
useful in estimating the morphology and content
of the atheroma.
I. Soft (echolucent) plaques refer to the acoustic signal that
arises from low echogenicity instead of plaque’s structural
characteristics. Although a zone of reduced echogenicity
generally results from high lipid content in a mostly cellular
lesion, it could also result from a necrotic zone within the
plaque, an intramural hemorrhage, or a thrombus.
30. Atheroma Morphology
• Fibrous plaques have an intermediate echogenicity
between soft (echolucent) atheroma and highly echogenic
calcific plaques.
• Generally, the greater the fibrous tissue content, the
greater the echogenicity of the tissue.
• Ultrasound imaging is more sensitive than fluoroscopy for
coronary calcification detection.[Large calcifications may be
associated with lesion stability. In contrast, micro
calcifications are frequently found in lipid-rich necrotic core
areas of unstable plaques and may not be well reflected in
intravascular ultrasonography images.
31. Atheroma Morphology
• Plaques frequently contain more than one
acoustical subtype.
• A thrombus is usually recognized as an intraluminal
mass, often with a layered, lobulated, or
pedunculated appearance.
• However, in vitro studies have revealed limitations
of intravascular ultrasonography in the diagnosis of
thrombi (sensitivity of 57% and specificity of 91%),
considerably inferior to conventional angiogram.
32. Atheroma Morphology
• The intimal hyperplasia characteristic of early in-stent
restenosis often appears as tissue with very low
echogenicity, at times less echogenic than the blood
speckle in the lumen.
• Appropriate system settings are critical to avoid
suppressing this relative nonechogenic material. The
intimal hyperplasia of late in-stent restenosis often appears
more echogenic.
34. Evaluating Dissections And Other
Complications After Intervention
• Intravascular ultrasound is commonly used to detect
and direct the treatment of dissections and other
complications after intervention.
• IVUS allows for detailed classification of dissection and
assessing the severity of the dissection.
• Important characteristics of a dissection are identified
distinctly by intravascular ultrasonography such as-
– Presence of a false lumen,
– Identification of mobile flap(s),
– Presence of calcium at the dissection border,
– Dissections in close proximity to stent edges
36. Unstable Lesions And Ruptured
Plaques
• Although no definitive features define a plaque as
vulnerable on IVUS , a hypoechoic plaque without a
well-formed fibrous cap is presumed to represent
potentially vulnerable atherosclerotic lesions because
this represents a lipid-rich with a thin fibrous cap.[26]
• In patients studied after an acute coronary syndrome,
ultrasound imaging may reveal ulceration, often with
remnants of the ruptured fibrous cap evident at the
edges of the ulcer. Various other appearances are
common, including fissuring or erosion of the plaque
surface.
38. Unusual Lesion Morphology
• Intravascular ultrasonography can be used to
characterize unusual lesion morphology, such
as aneurysms, pseudo-aneurysms, and true
versus false lumens.
39. Ambiguous lesions
• IVUS lends itself to the identification of technically
difficult lesions, such as intermediate lesions of
uncertain stenotic severity or ostial stenosis and
disease at branching sites.
• IVUS can also be helpful for delineating lesions
involving tortuous vessels and left main stem lesions.
• IVUS has a particularly important role in defining areas
with intraluminal filling defects, angiographically hazy
lesions, sites with plaque rupture, and lesions with
local flow disturbances.
• IVUS can be used to determine vein graft morphology
in situ as well.
40. Special Disease Considerations
• In-stent Restenosis
• Assessment of transplant vasculopathy
• Aortic, carotid, and peripheral vascular
disease
