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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3676_Библиотеки_им_академика_М_И_Перельмана
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T.A. Hameed
14.4.3 Diagnosis
Bicuspid aortic valve with heavy calcification.
14.4.4 Discussion
The bicuspid aortic valve (BAV) presents special
challenges for transcatheter valve implantation.
The asymmetric shape and associated fibrotic or
heavily calcified cusps can lead to abnormal
expansion or suboptimal alignment of the prosthetic valve, which may cause significant aortic
regurgitation. The detection of BAV may sometimes be difficult on transthoracic echocardiography due to calcifications or in patients with large
body habitus and BAV may initially be diagnosed
on CT, performed for pre-TAVR valve sizing.
The data regarding long-term outcomes of TAVR
in BAV is limited.
14.4.5 Pearls and Pitfalls
14.5.2 Findings
Figure 14.31 demonstrates the height of the
ostium of left main coronary artery from the level
of aortic valve annulus measuring 5.6 mm and
the height of ostium of right coronary measuring
10.9 mm. The ostium of LMCA is at the level of
mid portion of sinus of Valsalva on the transaxial
view (Fig. 14.32) indicating low position.
Images during TAVR demonstrate catheterization and opacification of left coronary artery
(Fig. 14.33) and balloon expansion of the aortic
valve with the catheter in left coronary artery
(Fig. 14.34). Figure 14.35 shows the implanted
aortic valve with patent left coronary artery.
The shape of the annulus of BAV is more likely to
be elliptical than circular and CT is thus particularly important in BAV for accurate sizing for
prosthetic valve implantation, which currently is
circular in shape. Pre-TAVR CT can provide initial diagnosis of bicuspid aortic valve or confirmation of findings on echocardiography and also
provide information regarding the degree of calcifications, which may affect valve alignment.
14.5 Case 4
14.5.1 History
A 98-year-old female with severe aortic valve
stenosis for pre-procedure CT evaluation for
TAVR.
Fig. 14.31 Low ostium of left main coronary artery
(LMCA)
Fig. 14.32 Transaxial view at the level of mid sinus of
Valsalva showing the ostium of LMCA
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Fig. 14.33 Angiogram with opacification of left coronary artery
Fig. 14.34 Fluoroscopy image during balloon expansion
of prosthetic aortic valve with a catheter in LMCA
Fig. 14.35 Angiography image showing the implanted
aortic valve and patent LMCA
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T.A. Hameed
14.5.3 Diagnosis
Low height of LMCA ostium from the aortic
valve annulus.
14.5.4 Discussion
The low position of the ostium of the coronary
artery predisposes it to the risk of occlusion due
to displaced cusp of the native calcified aortic
valve during prosthetic valve implantation or
potentially due to superimposition of the prosthetic aortic valve. Coronary ostia height of less
than 10 mm increases the risk of coronary occlusion which depends on specific type and size of
prosthetic valve to be implanted. The risk is
higher with larger size of aortic valve. It is therefore important to accurately assess the height of
coronary artery ostium from the plane of aortic
valve annulus as these patients may become
unsuitable for TAVR. In the case above, the
ostium of left coronary artery was protected during the valve implantation by placing a catheter
into it.
14.6.2 Findings
Cardiac gated CTA images demonstrate prosthetic aortic valve (Figs. 14.36, 14.37, 14.38,
14.39, 14.40, 14.41, 14.42, 14.43, 14.44, and
14.45).
Figure 14.36 shows images of the valve in
transaxial plane, generated from oblique coronal
(Fig. 14.37) and oblique sagittal views (Fig. 14.38).
Figure 14.39 shows inner luminal diameter of
18 × 17.7 mm for this valve with nominal diameter of 25 mm.
Figures 14.40 and 14.41: The valve posts are
visualized as hypodense structures; but the leaflets are not visible on CT. The three hyperdense
structures represent superior margin of the valve
posts to which the leaflets are attached.
Figures 14.42, 14.43, 14.44, and 14.45: Virtual
ring drawn around the valve posts at the level of
superior margin demonstrates a distance of
2.7 mm to the LMCA ostium.
14.5.5 Pearls and Pitfalls
Demonstration of the coronary ostia in appropriate planes on CTA for accurate assessment of
height helps pre-procedure planning. Depending
on overall condition and other risk factors for the
patient, TAVR could be performed by modifying
the implantation technique.
14.6 Case 5
14.6.1 History
An 80-year-old male with prior history of surgically placed bioprosthetic aortic valve (25 mm
SJM Biocor valve); now presenting with valve
dysfunction with aortic stenosis and regurgitation
on echocardiography. CT is performed for preTAVR evaluation.
Fig. 14.36 Transaxial view at the level of bioprosthetic
valve
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Fig. 14.37 Oblique coronal view with reference axial
plane through the level of bioprosthetic valve
Fig. 14.38 Oblique sagittal view with reference axial
plane through the level of bioprosthetic valve
Fig. 14.39 Transaxial view: bioprosthetic valve luminal
diameter
Fig. 14.40 Transaxial view showing hypodense valve
posts
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T.A. Hameed
Fig. 14.41 Oblique sagittal showing valve posts
Fig. 14.42 Transaxial view at the level of superior mar-
gin of valve posts
Fig. 14.43 Transaxial view with a virtual ring drawn
Fig. 14.44 Transaxial view with a virtual ring drawn
with superior margin demonstrating a measured distance
mm to the LMCA ostium
of 2.7
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Fig. 14.45 Coronal view with reference axial line at the
level of superior margin of valve posts and LMCA ostium
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14.6.3 Diagnosis
Prosthetic aortic valve with inner luminal diameter
of 18 × 17.7 mm. The distance of virtual ring at the
level of superior margin of valve posts from LMCA
ostium is 2.7 mm which will be at high risk for
coronary obstruction for valve-in-valve TAVR.
14.6.4 Discussion
Bioprosthetic surgical aortic valves include
stented and stentless variety. These valves are
surgically placed at or above the level of native
annulus. Dysfunction of bioprosthetic valves
may present with stenosis or regurgitation or both
and is treated with surgical replacement. TAVR
with valve-in-valve treatment is performed in
patients who are at high risk for surgical repair.
The valve-in-valve procedure is associated with
higher risk of complications which include postprocedure high trans-aortic gradients, malposition
of the valve, and coronary obstruction. However,
the risk of annulus rupture or conduction system
abnormalities is low, as the annulus may be protected by the firm ring of the surgical valve.
The diagnosis of dysfunction of surgical aortic
valve is made by echocardiography. CT is used for
pre-TAVR planning including the assessment of
luminal diameter which is different from the nominal diameter and orientation of the valve, which
may be tilted from the long axis of aortic root.
The assessment for expected position of displaced cusps of surgical valves relative to coronary
ostium is also relevant for pre-procedure planning.
A large size of aortic root is at low risk for coronary
occlusion. Drawing a virtual ring of anticipated
THV size at the level of superior margin of the posts
of the bioprosthetic valve on pre-TAVR CT images
has been proposed to evaluate the relationship with
the coronary ostium. A distance of less than 3 mm is
considered high risk for coronary occlusion and a
distance greater than 6 mm is at low risk with valvein-valve replacement by transcatheter heart valve
(THV). The risk of coronary occlusion can be
reduced by low placement of THV or placing a THV
with smaller diameter to reduce lateral displacement
of valve posts and leaflets.
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14.6.5 Pearls and Pitfalls
The nominal size of the surgical valve commonly
refers to the outer diameter or sewing ring size,
whereas the inner luminal diameter is used for
TAVR size selection. The bioprosthetic valve
leaflets are not visible by CT. CT can be useful in
detecting thrombus or calcifications within the
dysfunctional prosthetic valve.
14.7 Case 6
History: An 88-year-old with severe aortic stenosis and decreased renal function; for pre-TAVR
evaluation CT with low contrast dose.
14.7.1 Findings
ECG-gated helical CTA examination of the chest,
abdomen, and pelvis performed with total contrast volume of 28 mL (Iopamidol 370 mgI/dL)
with 80 KV technique (Figs. 14.46, 14.47, 14.48,
14.49, 14.50, 14.51, 14.52, 14.53, 14.54, 14.55,
14.56, 14.57, 14.58, and 14.59).
Fig. 14.47 Graph
generated from bolus
timing run (Fig. 14.46)
showing the time of
contrast arrival in aorta
Fig. 14.46 80 KVp technique: Bolus timing run with
1 mL at ascending aorta
90
85
80
75
70
65
60
55
50
0510 15
t[sec]
T1
t[sec]= 21.76
[HU]= 93.68
20 25
TLCT Graph
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Fig. 14.48 80 KVp technique: Bolus timing run with
2
mL contrast at external iliac arteries
110
105
100
95
90
85
80
75
[HU]
70
65
60
55
Fig. 14.49 Graph
generated from bolus
timing run (Fig. 14.48)
showing the time of
contrast arrival in iliac
50
45
40
0510 15
arteries
T1
t[sec]= 31.08
[HU]= 112.5
20
25 30 35 40 45
t[sec]
T1
T2
413
Fig. 14.50 80 KVp technique with 25 mL contrast:
Contrast enhanced aortic root at sinus of Valsalva with
attenuation of 339 HU
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Fig. 14.51 80 KVp
technique: Contrast
enhanced iliac arteries
with attenuation of 210
HU and 222 HU
T.A. Hameed
Fig. 14.52 Oblique coronal view to select appropriate
axial plane for aortic annulus
Fig. 14.53 Oblique sagittal view to select appropriate
axial plane for aortic annulus
Fig. 14.54 Axial image of annulus with borders
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Fig. 14.55 Axial images of: annulus, sinus of Valsalva, sinotubular junction, and LVOT
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Fig. 14.56 Measurement images of: ascending aorta, and distance of LMCA and RCA from annulus
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