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Transcatheter Aortic Valve Replacement
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Table 4 The heterogeneous spectrum of bicuspid aortic value morphology
29
Adapted and reprinted from Journal of Cardiovascular Computed Tomography, Vol 13/1, Philipp Blanke, Jonathan
R.Weir-McCall, Stephan Achenbach, Victoria Delgado, Jörg Hausleiter, Hasan Jilaihawi, Mohamed Marwan, Bjarne
L.Norgaard, Niccolo Piazza, Paul Schoenhagen, Jonathon A.Leipsic, Computed tomography imaging in the context of
transcatheter aortic valve implantation (TAVI)/transcatheter aortic valve replacement (TAVR): An expert consensus
document of the Society of Cardiovascular Computed Tomography, 1–20, Copyright 2019, with permission from
Elsevier
“sh mouth” appearance and systolic doming of
the valve apparatus with color doppler providing
further information in differentiating tricuspid
from bicuspid valves in the presence of calcication and reduced leaet mobility [5]. However,
anatomic assessment, including bicuspid valve
type, annular shape, and calcium distribution is
limited by echocardiography [68] (Fig.23).
Given the diagnosis of severe, symptomatic AS
and bicuspid aortic valve, a preprocedural CT
scan was ordered and demonstrated an aortic
annular area of 394mm2 with a bicuspid type 0
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Fig. 22 2D TEE (left panel) 2D TTE parasternal long axis (right panel) demonstrating severely calcied aortic valve
a b c
abc
K. Sewnarain et al.
d
d
Fig. 23 Post contrast Pre TAVR planning CT images
with measurements performed in the systolic phase of the
cardiac cycle. (a) Annular area of 394mm
of 71.4mm. (b) The Left main coronary artery ostium is
located 16.4mm and the (c) right coronary artery ostium
2
and perimeter
valve and severe nodular calcication at both
leaets. There was moderate annular calcication with a calcied nodule protruding into the
annular lumen and a short intervalvular brosa.
Risk of coronary artery obstruction was low with
both right and left main coronary artery heights
of 16mm, a sinus of Valsalva diameter averaged
at 35 mm and an STJ height of 18 mm. The
ascending aorta was dilated but less than 45mm.
An orthogonal projection was possible at a left
anterior oblique and caudal angulation of 10 and
e f
is 15.6mm above the annular plane suggesting low risk
for coronary obstruction. (d) The sinotubular junction
measures 28.3× 28.6mm in diameter and is located (e)
18.3 mm above the annular plane. (f) The Sinus of
Valsalva is capacious and measures 35.3cm in diameter
21° respectively. Femoral access was feasible
bilaterally.
CT is integral in the planning for the TAVR
procedure particularly in bicuspid aortic valves
due to the heterogeneity of the various bicuspid
valve morphologies that has a potential to
inuence the patients outcome [66]. MDCT demonstrates accurate correlation with surgical ndings and has improved diagnostic sensitivity
when compared to TTE and TEE [68]. CT or
MRI are recommended if echocardiographic
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assessment of the sinus of Valsalva and ascending
aorta is suboptimal and inconclusive [4].
CMR provides good assessment of valve morphology with the ability to accurately determine
velocities and gradients and annular size [68].
However assessment of calcication is limited
[68].
Important features to be assessed by 3D imaging (ideally by CT but possible by CMR, or 3D
TEE as well) include valve morphology [15] and
the degree of raphe calcication assessed qualitatively as mild, moderate and severe. A raphe particularly if calcied may affect TAVR expansion
and apposition at the annulus [66, 69] and
increases pacemaker requirement risk, risk of
device misplacement and regurgitation [69]. The
bicuspid aortic valve annulus is relatively larger,
often demonstrating an elliptical shape and more
often exhibiting severe eccentric calcication
when compared to tricuspid valves [65]. Note
should be made that non raphe bicommissural
bicuspid aortic valves demonstrates a larger sinus
diameter but smaller annuli [15]. Landing zone
conguration may be tubular, ared or tapered
(classied by relative perimeters of the annulus
and at the level of the free edge of the leaets)
[69]. An aortic root with a tapered conguration
may require THV under sizing or sizing at dimensions closer to the supra annular measurements
[69]. There are two schools of thought regarding
annular measurement and include sizing at the
annulus and/or supra annular tracing (measuring
perimeter and intercommissural distance approximately 4mm above annulus) [70]. These may be
supplemented by balloon sizing [70]. The
BAVARD registry states that annular measurements are suitable in almost 90% of cases [70].
Inappropriate oversizing can result in annular
rupture and heart block [65]. The annular ellipticity, calcium burden and location should be
assessed [67]. Heavy and asymmetric calcications are a concern and may result in impaired
valve expansion or aortic root injury following a
countercoup injury from balloon ination and
THV expansion [67]. Calcium located at the
commissures can result in perforation whilst
bulky calcication located at the tip of a leaet is
a risk for coronary obstruction [69]. Spacious
sinuses in patients with BAV is often protective
from coronary occlusion [69]. The ascending
aorta should be assessed for aortopathy and dilatation [15]. Optimal projection angles can be
obtained using MDCT software providing coaxial angles with optimal assessment of calcication [70] (Fig.24).
In light of the patient’s likely suitability for
TAVR, a pre-procedural angiogram was obtained
to evaluate the coronary arteries and further
evaluation of the aortic root. There was no signicant coronary artery disease with aortic root
calcication (Video 19). The ascending aorta
was dilated. Femoral access had favorable imaging features bilaterally.
Dierential Diagnosis
Pre echocardiography differentials of lung
pathology, mitral valve disease and congestive
heart failure were excluded following imaging
conrmation of severe aortic stenosis.
Heart Team Approach andDiscussion
Based on the diagnoses of severe AS in a patient
with bicuspid aortic valve, reasonable root features and maximal aortic dimension of 41mm on
CT and 42mm on TTE the decision was to proceed with TAVR using a 23mm SAPIEN 3 Ultra.
Heart Team Decision
Bicuspid valves often have a larger annulus, an
asymmetric valve orice, are heavily calcied,
have a dilated and asymmetric aortic root and
ascending aorta [40]. Complications such as signicant PVL, device migration/embolization,
non-uniform non circular valve deployment and
annular rupture are more common [40]. Success
rates are good with newer generation TAVR
valves with improved outcomes in Sievers Type 1
L-R fusion [5]. Similar outcomes were achieved
in low surgical risk patients with BAV (without
raphe or leaet calcication), when compared
with TAVR patients with similar clinical prole
but with tricuspid valves and treated with
SAPIEN 3 THV [71]. Patients with BAV and
high surgical risk treated with EvolutR/Evolut
PRO demonstrated similar outcomes in terms of
1year post procedural stroke and mortality rates
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d e f
K. Sewnarain et al.
Fig. 24 (a) Angiogram of the aortic root with mildly
dilated ascending aorta and no signicant adverse root
features and coronary ostial heights were at low risk for
obstruction. (b–d) Coronary angiogram of the RCA and
when compared to their tricuspid aortic valve
counterparts [72].
Denitive criteria between the choice of
SAVR and TAVR is still to be decided with SAVR
preferred in young patients, patients with aortopathy and low risk patients [73]. Currently features
conducive for TAVR in BAV include a favourable
annular dimension, absence of severe leaet and
raphe calcication especially in Sievers type 1
and with Sievers type 0 (in the absence of an
extreme ellipsoidal annulus) [73]. Of note, in
patients with bicuspid morphology treated with
TAVR, there is a higher incidence of conduction
abnormalities [5] and the presence of severe calcication of the raphe and leaets is associated
with aortic injury and higher incidence of PVL
with a higher 2year mortality especially if both
leaet and raphe calcication were present [74].
There is however reduced incidence of PVL with
newer generation devices [75].
LM and its branches showed patent vessels with no
requirements for percutaneous intervention or bypass
grafts. (e and f) patent iliofemoral arteries without signicant calcication, tortuosity or stenosis
Intra Procedural Assessment
The aortic valve was predilated using a 20mm
balloon (Fig. 25, Video 20). The patient then
demonstrated high degree A-V block requiring
pacing. A 23mm Sapien 3 valve (−2cc) was successfully deployed under rapid pacing (Fig. 25,
Video 21) using uoroscopy.
Balloon Sizing andPre Dilatation inBicuspid
Valves
Pre-dilatation is recommended for balloon annular sizing in borderline dimensions, in fused right
and non-coronary cusps, when considering sizing
to the supra annular space and in the presence of
heavily calcied bicuspid aortic valve with a calcium score >1000HU (to assist in crossing the
native valve and prosthetic valve deployment)
[69]. The region of balloon waisting will identify
the position of best sealing whilst approximation
of calcied leaets to the coronary ostia will
cd
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a b
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Fig. 25 (a) Pre deployment balloon valvuloplasty with
balloon placed across the aortic valve and inated with
displacement of leaet calcication. (b–d) A Sapien 3
assist in determining risk of coronary obstruction
[69]. Absence of a leak supports congruent balloon and valve orice dimensions [69].
Post Procedural Assessment
Formal postprocedural TTE demonstrated a well
seated aortic transcatheter heart valve with a
mean gradient of 10 mmHg, Peak velocity of
2.3m/s and an aortic valve area of 1.4cm2 (Fig.
26). Mild paravalvular prosthetic regurgitation
was present and leaet motion was poorly
visualized.
bioprosthetic valve was deployed at the annulus with minimal tailoring in its mid portion
Postprocedural electrophysiology assessment
resulted in permanent pacemaker placement
(Fig. 27) 30days post procedure echocardiogram
revealed a well seated aortic valve with poor
visualization of leaet motion. Mild paravalvular
regurgitation persisted and was non-progressive.
Aortic peak velocity had increased to 3.3 m/s
with a mean gradient of 21 mmHg. There was
mild mitral regurgitation with no systolic anterior
motion of the mitral valve. Concentric hypertrophy of the left ventricle remained stable. No pericardial effusion, septal defects or intracardiac
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abc
Fig. 26 2D TTE post procedure demonstrating normal valve position (a) with mild paravalvular regurgitation (a and
b), mild mitral regurgitation and acceptable hemodynamic parameters (c)
ab c
Fig. 27 (a and b) 2D TTE 30days post TAVR procedure with (a and b) demonstrate persistence of mild paravalvular
regurgitation. (c) Continuous wave doppler echo shows an elevated mean gradient at 21mmHg
shunts were present. Pacemaker leads identied
in the right atrium and right ventricle.
Similar to the post-procedure evaluation of
TAVR valves placed for severe, symptomatic AS
in tricuspid aortic valves, post-procedure imaging
is based initially on echocardiography.
Postprocedural echocardiography should be
Valve dimensions demonstrated under-
expansion (Fig. 28) of the valve in its midportion
(17mm diameter) with no thrombus or HALT.No
VSD or pericardial effusion present and pacemaker leads were appropriately positioned.
Aortic dimensions were stable with no aortic root
injury.
focused on valve hemodynamics, the presence of
aortic regurgitation, biventricular function, the
function of the other three cardiac valves, and evidence of any intracardiac complications, such as
cardiac perforation. Given the often-ovular nature
of the bicuspid valve annulus, assessment for aortic valve regurgitation is of particular importance,
Complications inBicuspid Aortic Valves
Patients with BAV have a higher risk of malposition [64], pacemaker rates [70] and paravalvular
regurgitation with lower device success rates [15]
above and beyond the standard TAVR complica-
tion prole.
with posteriorly located regurgitant jets being
most difcult to visualize due to metal shadowing
from the valve frame. In the present case, an
increase in 30-day TAVR gradients as compared to
the post-procedure assessment suggested potential
valvular dysfunction versus leaet abnormality
and prompted a contrasted cardiac CT.
Paravalvular Regurgitation
Paravalvular leak occurs when the THV incom-
pletely approximates annulus and LVOT [47].
Incidence of moderate to severe paravalvular
regurgitation is higher in a bicuspid valve with a
calcied raphe and, higher still, if both the raphe
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ab c
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Fig. 28 Post procedure post contrast CT performed to
assess for valve expansion and exclude complications. (a)
Sapien 3 valve 23mm that was underlled by 2cc demonstrates mild tailoring at the mid portion of the valve. (b)
Short axis image of the valve at the mid portion demon-
Table 5
Bicuspid aortic valve multimodality imaging
Bicuspid valve
± aortopathy Echocardiography Computed tomography MRI
Pre procedure
imaging
Intraprocedure
imaging
Postprocedure
imaging
First line for valvular assessment
with high accuracy especially on
TEE. Accurate assessment may be
limited in the presence of severe
calcication. Limited assessment of
co-existant aortopathy
Similar to tricuspid aortic valves (see case 1) with the exception that TEE may play a larger role in
device positioning in the absence of severe calcication to serve as a landmark on uoroscopy
Similar to tricuspid aortic valves (see case 1)
and leaets are calcied [74]. Sievers type 1 BAV
was associated with a relatively higher rate of
PVL in comparison to other classications, however there no signicant difference in paravalvular regurgitation between the self and balloon
expandable valves in all classication types [48].
Table5 showing role of Multimodality Imaging
in TAVR in Bicuspid Aortic Valve.
strates a diameter of 17.12mm by 19.2mm. Conrming
mild under expansion with no leaet thickening or throm-
bosis. (c) Long axis view of the valve conrms mild under
expansion of the mid portion of the valve
Improved diagnostic sensitivity
when compared to
echocardiogram. Recommended
in assessing sinus of Valsalva and
ascending aorta if echo
assessment is inconclusive
Good assessment of
valve morphology and
function as well as
aortic morphology and
pathology. Limited by
calcication
system in self-expanding cases are thought to be
aetiological contributory factors [70].
Features predictive of conduction disturbances
include calcication of the LVOT, especially
below the non-coronary cusp and severe mitral
annular calcication (>180°) [47]. The presence
of a short membranous septum [47] less than
8 mm in length is a predictor for high degree
AV-Block, especially if found in combination
Post Procedure Pacemaker Requirements
Higher pacemaker rates are documented in
patients with bicuspid aortic valves post TAVI
more so in balloon expandable instances which
has a 23.5% post implantation pacemaker rate
[70]. Lack of foreshortening of the stent frame of
balloon expandable valves during oversizing and
excessive force being applied to the conduction
with low valve implant and an underlying right
bundle branch block [15]. Procedural risks include
the use of a self expanding THV [47, 76], low
valve placement of greater than 4mm below the
annulus [47] and annular and LVOT oversizing
[76]. Low deployment is the most frequent predictor of LBBB with balloon and self- expandable
valves [15]. Reduction of the implant depth sig-
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nicantly reduces mortality and pacemaker
requirements [15]. The short term effects of
edema, inammation, ischemia or direct trauma
may demonstrate recovery thereby negating long
term pacemaker dependency post TAVR [76].
Clinical Controversies andPearls
• Trials of FDA approved TAVR valves excluded
patients with bicuspid aortic valves. As a
result, randomized comparisons of TAVR vs.
SAVR for bicuspid aortic valves is lacking.
• Bicuspid aortic valve disease is associated
with aortopathy and other left sided cardiac
lesions. As a result, careful evaluation of these
structures is necessary when planning for
treatment of severe symptomatic bicuspid aortic valve disease.
Key Points
– The degree of raphe calcication should
be assessed qualitatively as mild, moderate, and severe. A raphe especially when
calcied may affect expansion and apposition of the TAVR at the annulus, risk of
requiring pacemaker, device misplacement, root injury and regurgitation.
– Non raphe bicommissural bicuspid aor-
tic valve have a larger sinus diameter but
smaller annuli.
– Calcium at the commissures can result
in perforation. Bulky calcication at the
tip of the leaet is a risk for coronary
obstruction.
Aortic Regurgitation
Case Study
Background andDenitions
Aortic regurgitation (AR) refers to the retrograde
blood ow from the aorta into the left ventricle in
diastole secondary to lack of aortic valve leaet
coaptation [77].
Isolated (AR) is less common than symptomatic (AS) and affects approximately 13% of
patients with pure left sided native valve disease [78]. The estimated prevalence of at least
moderate AR in those older than 70years is
2.2% [79]. Less than 1% of transcatheter aortic
valve implantation is done for AR in the United
States [80]. Chronic AR is clinically asymptomatic for prolonged periods. Thereafter
patients develop congestive heart failure, secondary to volume overload, left ventricular
dysfunction and increased wall stress [81].
Valve replacement should be performed when
regurgitation is severe and the patient is symptomatic, or when the left ventricle end systolic
dimension is >50 mm (index left ventricular
end systolic dimension is >25mm/m2) [82] or
there is left ventricular systolic impairment
[83].
The pathophysiology of AR differs from AS
(degeneration and calcic disease [77]) and
causes include:
• Congenital [81]
• Bicuspid Valve [80]
• Infectious [81]
• Rheumatic heart disease [80]
• Previous endocarditis [80]
• Vasculitis [81]
• Calcied/myxomatous leaets [77]
• Connective tissue diseases [80]
• Aortic root dilatation [80] secondary to
trauma, dissection, viruses or arteritides [77]
• Radiotherapy [81]
An 83-year-old male patient presented with
NYHA class II symptoms without chest
pain or syncope. He has had multiple prior
hospitalizations for congestive cardiac
failure. Physical examination revealed a
grade 2 diastolic murmur loudest in the
third intercostal space.
Diagnosis andPre-procedural
Evaluation
A TTE demonstrated a trileaet, sclerotic aortic
valve with mild reduction in cusp motion. There
was moderate to severe aortic regurgitation with
a regurgitant volume of 45 mL, an EROA of
0.23cm2, a P1/2T of 381ms and a vena contracta
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of 5mm. The left ventricle was severely dilated
and globally hypokinetic with left ventricular
hypertrophy and a reduced systolic function of
25%. The proximal ascending aorta was dilated,
indexed at 20mm/m2.
Transthoracic Echo
TTE is the gold standard for workup [77] and
assesses the mechanism and severity of regurgitation, valve type, and left ventricle remodelling
and function [84]. Leaets are assessed for noncoaptation and prolapse and multiple measures
are assessed and integrated to determine the
severity of regurgitation [83]. Additionally, left
ventricular end systolic dimension, ejection fraction, aortic root and ascending aorta are also
assessed [83].
Severe AR:
• Ratio of regurgitant jet width to LVOT width
≥65% [84].
• Vena contracta >0.6cm [83].
• Effective regurgitant orice area ≥0.3 cm2
[84].
• Regurgitant volume >60mL and regurgitant
fraction ≥50% [84].
• Deceleration time (pressure half-time) of the
continuous wave aortic regurgitation doppler
jet of <200ms [83].
• Reversal of ow in the descending aorta
throughout diastole particularly when in conjunction with end diastolic velocity of
>20cm/s [83].
Caveats:
• Linear measurements are based on the presumption of a circular orice from a single
plane of assessment. The accuracy may therefore be increased with 3D TTE [83].
• Pressure half time varies with blood pressure
and LV compliance and is often lower in acute
AR [83].
Transoesophageal Echo
TEE is usually performed if a more detailed
assessment of the aortic valve or aortic root is
required [84]. Both 2D and 3D TEE provide
diagnostic value in dening mechanisms of AR
[84]. Pre procedural TEE provides information
for device sizing whilst intraprocedurally it is
used to visualise bioprosthetic valve positioning and assess for immediate complications
[83]. TEE can also assess the valve morphology
to enable valve preserving repair in some
patients, especially those with aneurysms of the
aortic root as well as regurgitation in non-calcied bicuspid valves [83]. Of note, doppler
angles for assessing aortic regurgitation (for
calculations such as aortic pressure ½ time or
PISA EROA) are usually suboptimal in TEE as
compared to TTE and necessitate deep transgastric imaging.
Cardiac Magnetic Resonance Imaging
CMR is the gold standard for the assessment of
left ventricle volumes and ejection fraction [83].
In AR CMR may be used for valve planimetry, to
determine the mechanism and quantify the severity of aortic regurgitations and the presence of
aortopathy [84]. CMR is indicated when the echo
is suboptimal or when there is a discordance
between either echo and clinical ndings or in
determining AR severity between echo and doppler results [84]. CMR is also indicated when
echo is limited in assessing aortopathy or in the
presence of multiple valvular pathologies [84]. In
addition, CMR is useful in follow up assessment
with less variability then echo in determining the
severity of AR and LV remodeling and is benecial in long term assessment of aortopathy in
coexistent AR and a bicuspid aortic valve [84].
Aortic regurgitant volume and fraction is determined by phase contrast velocity mapping of the
aortic valve or in the absence of other valvular
lesions by determining the difference between
the aortic and pulmonic stroke volumes [84]. An
aortic regurgitant orice of ≥48cm2 and a holodiastolic ow reversal in the mid descending
aorta where found to be sensitive in detecting and
predicting severe AR [84]. Left ventricular dilation with end diastolic volume >246mL predicts
symptom onset and possible requirement of valve
surgery whilst a regurgitation fraction >33% on
phase contrast predicts surgical need within
3years [83].
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In the present case, the patient had a sufcient
quality TTE to obviate the need for TEE or
CMR.However, since the etiology of the patient’s
LV dysfunction wasn’t clear, he underwent a coronary artery CT. There was no coronary artery
disease, and the patient was categorized as a
CAD-RADS 0.
Dierential Diagnosis
The possible diagnoses included coronary artery
disease which was excluded with a CT coronary
angiogram. Echocardiogram demonstrated features of severe aortic regurgitation and excluded
leaet vegetation. Echocardiogram also excluded
co existent signicant mitral valvular disease or
ASD. In light of the patient’s worsening aortic
regurgitation and the reduced left ventricular
function, the work-up for TAVR was commenced
(Fig. 29).
A pre TAVR CT was performed and demon-
strated a tricuspid non calcied valve with no
annular or LVOT calcication. The systolic annular area was measured at 405mm2. The risk for
coronary ostial occlusion is low with the left main
and the right coronary artery heights measuring
17.6mm and 17.9mm respectively. The average
SOV dimension is 31mm. The STJ diameter measured 25.9mm. The orthogonal view was obtained
at LAO 16° and CAU 20°, centered onto the right
cusp. There was dilatation of the left ventricle,
measured as LVEDD of 66mm LVESD of 58mm,
and both atria. The ascending aorta was dilated,
and this with the arch and descending thoracic
and abdominal aorta demonstrated no signicant
calcications, stenosis or tortuosity.
Computed Tomography
Computed Tomography is used primarily for preprocedural planning rather than diagnosis.
However, absence of complete coaptation of aortic
leaets during diastole can be used to detect aortic
regurgitation [85]. An anatomic regurgitant area
may be reliable to quantify severity with a value of
0.27 ± 0.16 cm2 suggestive of severe AR [85].
Regardless of symptoms, end—systolic diameter
of 55mm or greater or an ejection fraction below
55% are indications for intervention [85]. Risk
assessment for coronary obstruction, valve sizing
and aortic dimension are assessed similarly to
TAVR for aortic stenosis in the native valve.
Heart Team Approach andDiscussion
Only 1in 5 patients with severe AR and left ventricular ejection fraction between 30 and 50% are
referred to surgery [81]. The co-existence of multiple co-morbidities and the advanced patient age
abc
de
Fig. 29 (a) The annulus measures 405mm2 with a perim-
eter of 73mm. (b–d) Low risk of coronary obstruction
with coronary artery heights above 12mm and a capa-
f
cious sinus of Valsalva. (e) The RCC centered view provided a plane orthogonal to the annulus. (f) The left
ventricle is dilated measuring 66mm on end diastole
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