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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3737_Библиотеки_им_академика_М_И_Перельмана
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Transcatheter Aortic Valve Replacement
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Fig. 4 CT derived projection angles to guide uoroscopic procedure and obtain a plane orthogonal to the annulus (a)
right cusp centered view and (b) overlap view
abc
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Fig. 5 Short axis images of vascular access of the iliofemoral vessels. Images assessed for degree of calcication. (a)
Mild crescentic non protruding calcication. (b) Horseshoe calcication. (c) Near circumferential calcication
RAO 10 CAU 22 and a right cusp centered view
could be achieved at RAO12 CAU2 (Fig. 4).
The were no imaging features prohibitive of
bifemoral vascular access. There was mild tortuosity and calcic atherosclerotic plaque with
minimal luminal diameters of 6mm in the external iliac arteries on each side (Fig. 5). The
ascending aorta had no calcic atherosclerotic
plaque. The aortic arch, descending thoracic and
abdominal aorta had coalescing non protruding
atherosclerotic changes. There was no signicant
vascular tortuosity (Fig. 6).
bility of future coronary access post TAVR [11].
Cautious attempts at crossing the aortic valve at
time of pre procedural angiogram predicts ease of
successful negotiation of the valve during the
TAVR procedure (however an unsuccessful
attempt does not preclude TAVR) followed by LV
catheterization to determine, trans aortic pressure
gradient, annulus area and the severity of aortic
stenosis especially in the setting of discrepant
echocardiography results [11] or discordant clinical and non-invasive imaging ndings [4].
Assessment of pulmonary artery pressures, pulmonary vascular resistance and cardiac output
Cardiac Catheterization
Preprocedural cardiac and coronary catheterization
is performed to determine the presence and severity of coronary atherosclerotic disease and feasi-
may also be obtained during right heart catheterization [11]. Access route feasibility for TAVR
may also be assessed via aortography and pigtail
catheterization [8, 11]. It allows for determination
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Fig. 6 3D Volume rendered image assessing tortuosity of
the vessels being considered for access. Mild tortuosity of
iliofemoral vessels
K. Sewnarain et al.
of tortuosity, degree of calcication and luminal
caliber [11] however assessment of the latter two
is limited [12]. Angiography also allows for
assessment of vessel movement with reduced
motion implying a more rigid and calcied artery
[13]. Accurate assessment of luminal dimension
is however limited by lack of orthogonal images
in the acquired 2D planar views [8].
The present patient’s coronary angiogram
demonstrated patent grafts with signicant native
vessel disease. Aortic root had no dissection, dilatation, or severe calcication. Right heart catheterization had normal pulmonary arterial and
right atrial pressures. Cardiac output and Cardiac
Index where normal at 3.77L/min and 1.93 L/
min/m2 respectively (Fig. 7; Video 4). Right and
left iliofemoral arteries were feasible for transfemoral (TF) TAVR without severe stenosis, tortuosity or signicant calcication (Fig. 8; Video 5).
Although not required in our patient, CMR and
Nuclear Medicine are further tools in the diagnostic arsenal. CMR provides additional benet in
patients with iodine contrast allergies and impaired
renal function [11]. Non contrast CMR was found
to be equitable to CT and 2D echo in annular measurement, and further information in the form of
biventricular function, severity and presence of
AS, aortic regurgitation (AR) or mixed lesions and
determination of a physiological orice area [11].
Detection of mid wall brosis by late gadolinium
sequences portends left ventricular decompensation and mortality [14]. Calcium however limits
assessment of vascular access and aortic root especially in non- contrast studies [11].
a b c
Fig. 7 Angiographic assessment of the aortic root and coronary vessels. (a) Non dilated aortic root without severe
calcication. Evidence of prior CABG. (b) LIMA to LAD and SVG to PDA were patent. (c) Patent graft to the right
coronary artery
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Transcatheter Aortic Valve Replacement
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Fig. 8 Aorto femoral access was feasible with no signicant stenosis or tortuosity. Mild calcic plaque in the aorta and
both iliofemoral vessels
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Dierential Diagnosis
Decision Between SAVR andTAVR
Valve replacement treatment options include
Prior to testing, the patient’s signs and symptoms
were most consistent with a differential diagnosis
of progressive coronary artery disease and/or aortic stenosis. The patient’s echocardiogram,
cardiac catheterization, and cardiovascular CT
are most consistent with severe, symptomatic AS
as the cause of the patient’s symptoms. Based on
this diagnosis, evaluation for AVR is warranted.
SAVR (bioprosthetic or mechanical) or TAVR.
In patients less than 65years of age with no
high risk or prohibitive features for surgery and
with a life expectancy of greater than 20years,
SAVR is the preferred option, mainly due to
insufcient data on long term durability of TAVR
valves versus SAVR [4]. In patients with SAVR
the decision for a mechanical versus a bioprosthetic valve depends on patient preference, potential future childbearing, age of the patient,
Heart Team Approach andDiscussion
feasibility of long term anticoagulation use, and a
balance between a combination of valve hemody-
Given that the diagnosis of severe, symptomatic
AS has been made and a decision to evaluate for
the suitability of AVR has been made, the next
decision to be undertaken is TAVR vs. SAVR.On
the strength of a series of clinical trials of
encompassing both the Edwards Sapien and
Medtronic CoreValve TAVR platforms, TAVR
has been approved by Food and Drug
Administration for use in patients at low through
high risk of death or major complications during
open-heart surgery. As a result, shared decisionmaking between TAVR and SAVR is often based
on anatomy, patient preference, and other
considerations.
namic requirements, valve durability and
predicted future surgical risk prole [4]. Patients
between 65 and 80years with no contraindication to either SAVR or TAVR may receive either
procedure [4]. Patients over 80years or patients
with less than 10years predicted survival, TAVR
is preferred provided there are no contraindications [4]. In addition TAVR is preferred in patients
of all ages in whom SAVR is high risk or prohibitive and predicted post TAVR survival is greater
than a year with a reasonable quality of life [4].
Cardiac features detectable on imaging that
can favor SAVR include suboptimal annular and
aortic root ndings as listed in Table 1 below,
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Imaging parameters, their signicance in TAVR suitability, and reference values
Table 1
Reference values Signicance Key points
Annulus (measured
at blood tissue
interface
contouring through
calcication as if
not present [15])
Sinus of Valsalva
dimensions
(measured cusp to
commissure in
widest dimension
parallel to annulus)
[15]
Coronary to ostial
heights
LVOT Access for
STJ height
(shortest distance
between the
annular plane and
the lowest STJ
level)
STJ diameter
(widest and
orthogonal
dimensions at the
STJ plane)
<30mm [15] <30mm predicts risk of
12mm Less than 12mm is at high risk
calcication, sub
valvular
membrane, septal
hypertrophy [19]
Area and perimeter used for
valve sizing and referenced with
manufacturer sizing charts
coronary artery occlusion [15]
for occlusion [15]
There is increasing risk of
rupture with increasing severity
of calcication [19]
A STJ height and diameter less
than the prosthetic valve places
the STJ at risk of injury, of
particular importance in the use
of balloon expandable valves
[15].
Calcication at the STJ may
limit balloon and device
expansion with risk of device
migration [12]
K. Sewnarain et al.
– Smaller annular dimensions
acquired by 2D TEE than 3D TEE
which in turn were smaller than
those acquired by CT [16].
– Should be measured at the largest
dimension, usually 20% R-R
interval [16] usually at end systole
(i.e. the last phase before the
mitral valve opens).
– Annulus is predominantly
ellipsoid in diastole, approximates
a circular shape with a larger area,
perimeter and short axis diameters
in systole [16].
– Occasionally, in the presence of a
hypertrophied septum annulus may
be smaller in systole due to
protrusion of basal septum into the
annulus and left ventricular outow
tract (LVOT) [17], an appearance
referred to as inverse dynamism
– Risk of coronary occlusion
depends on a combination of sinus
of Valsalva (SoV) dimension,
coronary artery heights, leaet
heights, aortic root dimensions,
annular dimension and the choice
of prosthetic valve [15]
– An accessory coronary artery and
separate ostia of the conal artery,
left circumex (LCX) or left
anterior descending (LAD) should
be identied if present and
assessed for risk of occlusion [15].
– Ostial location within the sinus
varies with varying proximity to
the sinotubular junction (STJ),
annulus and commissures [18].
– A low coronary ostial height (less
than 12mm) should be considered
in combination with SOV
diameter, THV size, annular and
root dimensions [17]
– A STJ height less than the height
of the prosthetic valve, implies
extension of the valve beyond the
STJ and into the proximal
ascending aorta [15]
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Table 1 (continued)
Reference values Signicance Key points
0
Aortic angulation
(angle between the
horizontal plane
and annular plane
of the aortic valve)
[20, 21]
Landing zone
calcication
Ascending aorta Larger aortic diameters are more
48
Reduced immediate procedural
success, with increased risk of
device migration, increased
requirements for a second valve
and balloon dilation, increased
uoroscopy time and post
procedural paravalvular leak
(PVL) in patients with an aortic
angle of ≥48° [21]
Landing zone calcication, and
lack their off, plays an important
role in device anchorage [9]
however adverse outcomes from
annular and sub annular
calcication include PVL,
conduction abnormalities and
annular rupture [15]
commonly present in bicuspid
valve morphology, advanced age
and female gender (when
indexed to BSA) [23].
Ascending aortic calcication
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– No statistically signicant effect
of aortic angle on outcomes with
new generation valves i.e.
self-expandable or balloon
expandable [20, 22]
– Subjective assessment of number of
calcied foci and extent in radial,
inferior and circumferential directions
and described as mild, moderate or
severe. Location to the aortic leaets
and morphology of the calcium
namely crescentic/at or protruding
should also be accessed [15]
Concerns in the setting of AS and TAVR
include progressive dilation, aortic
dissection [24], rupture [24], PVL [25]
and an increase in all-cause mortality at
2years [25].
Measurement techniques vary from
inner wall to inner wall, outer wall to
outer wall and leading edge to leading
edge. 2D leading edge to leading edge
measurements were found to corelate
best with inner wall to inner wall
dimensions on CT and MRI [26].
Ascending aorta calcication (porcelain
aorta) favors TAVR over SAVR [4]
severe primary mitral regurgitation, dilation of
the aortic root and ascending aorta, septal hypertrophy, coronary artery disease requiring CABG,
whereas a porcelain aorta favors TAVR [4].
Preprocedural CT provides important information on access feasibility, potential uoroscopic projections of the aortic root, annular
sizing, aortic leaet and root calcication, risk of
coronary obstruction and identifying high risk
features for complications [11]. Complementing
anatomical coronary assessment, physiological
assessment with fractional ow reserve derived
from CT is safe and feasible with an acceptable
diagnostic accuracy in patients with AS [27].
Importantly, CTA can also be used to provide
information regarding vascular dimensions, calcication, tortuosity, all of which are important to
determine the optimal vascular access point for a
transcatheter intervention (Fig.9).
Access forTAVR
The advent of pre procedural screening has
reduced the incidence of major vascular complications, now occurring in 4–5% of procedures
[15]. Improvements in sheath size has reduced
the lumen size at which safe access can be
achieved however pre-procedural vascular imaging, usually by CTA, is recommended to alert the
heart team to precarious anatomy and pre- existing
vasculopathy [15].
Trans femoral (TF) access is preferred [28]
and demonstrates the lowest complication rate
[29]. In the event that TF access is not possible,
alternate workable access routes include trans
subclavian, trans aortic, trans apical, trans carotid,
trans caval and antegrade aortic approaches [28].
Trans aortic and trans apical approaches where
initially preferred alternative access routes but
following relative inferior outcomes in ran-
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From the conventional MPR imaging,the
optimal phase with the least motion and widest
annular orifice is chosen. Following double
oblique manipulation to obtain en face views of
the aortic valve,the annular plane is derived
from aligning the insertion points( B) of the
cusps. The annular areaand perimeter (A)are
measured optimally using the spline contour
with the margins at the interface between the
walls of the annulus and the opacified lumen.
K. Sewnarain et al.
The height of the right (C)and left main
(D)coronary arteries are obtained by a vertical
perpendicular measurement from the inferior
margin of the ostium, of each vessel , to the
annular plane.
The STJ diameter is acquired by perpendicular
axial dimensions at the level of the STJ( E).The
STJ height is is the lowest vertical perpendicular
height of the STJ to the annulus (F).
The sinus of Valsalva is an averaged dimension
of the three cusp to commissure distances (G) in
a plane parallel to the annulus at which the sinus
is at its widest.
c
d
ef
g
Fig. 9
Aortic annulus measurement by cardiac CT
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The right coronary cusp angle ( H) is obtained
in a plane bisecting the right coronary cusp
passing through the center of the lumen. The
overlap angle (I) is obtained by a line passing
through the center of the right and left coronary
cusps.
Access is determined by measuring the
narrowest points of the common iliac (J),
external iliac (K) and common femoral
arteries(L). The aorta is usually of an acceptable
dimension however in the presence of severe
stenosis this should be measured. Severe
circumferential, protruding or horseshoe
calcification, together with the presence of
penetrating ulcers, aneurysms or moderate to
severe vascular tortuosity should be noted.
Volume rendered images ( M and N) of the
aorta ,femoral and iliac arteries is best for
visualizing tortuosity.
hi
jk l
m
n
Fig. 9 (continued)
domised studies comparing SAVR to TAVR [29],
these are usually reserved for when all other
approaches are unsafe or not possible [11].
Mortality rates measured at 1 and 2 years post
procedure are similar in the TF and trans subclavian/axillary route, however mortality rates are
signicantly increased at both time frames in
trans aortic and trans apical access [30]. Use of
an alternate access is limited by institutional and
provider expertise [28].
CT is the preferred modality in preprocedural
vascular assessment and has led to a decrease in
major and minor complications [11]. Information
on calcication, tortuosity, luminal dimension, the
presence of aneurysms, vascular dissection and atheroma (which poses a risk for embolization) can be
easily ascertained [8]. Comprehensive assessment
includes analysis of 3D volume rendered images,
curved multiplanar reconstruction and maximum
intensity projections [31]. The minimal luminal
diameter may be underestimated due to blooming
artefact from calcium and overestimation of stenosis as a result of partial volume averaging [13].
Magnetic Resonance Imaging
Gadolinium MRI is comparable to CTA when
assessing vessel diameter and angulation [32].
There is however reduced sensitivity in calcied
vessels [32] and its use is limited in patients with
renal impairment [11]. Ferumoxtyol contrast
enhanced MRI provides a reasonable alternative in
the setting of renal dysfunction, limiting effects
from ow and motion when compared to a noncontrast MRI but extent of calcication may still
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K. Sewnarain et al.
be underestimated [33]. It is safe and diagnostic at
both 1.5T and 3T [33]. Non-contrast cardiac MRI
for pre-procedure AVR evaluation remains under
investigation, however, Pamminger etal. demonstrated strong correlation for luminal dimension
and tortuosity determination between non contrast
quiescent interval single shot MRI (QISS) and
contrast CT angiography, however QISS lacked
visualisation of calcied plaque burden [34].
In the present case all parameters of the aortic
root are normal with low risk of complications. In
addition, the patient has a stent and a saphenous
vein to posterior descending artery, left internal
mammary to left anterior descending artery and
venous to circumex artery grafts with low risk of
coronary obstruction. Additionally, there were no
signicant contraindications to transfemoral
access and TF TAVR.
Valve Choice
Choice for the patient: A 23mm Sapien Ultra.
The devices currently approved for TAVR in
the United States include the Edwards SAPIEN
and the Core Valve platforms [35]. The frequency
at which the valves are used depends on the
familiarity of the operators with the device as
well as the patients anatomic and clinical suitability [36]. There are multiple other TAVR systems approved in Europe and there will soon be
other TAVR systems available in the United
States as well. The principles for choosing
between these systems for an individual patient
will likely remain similar to what is described
above with patient anatomy and operator familiarity with TAVR systems likely remaining the
driving factors.
Fig. 10 Adapted from manufacturer instruction document
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Sapien 3 Valve (Fig.10)
Sapien 3 (S3) is a balloon expandable THV
designed to improve positioning, increase paravalvular sealing and decrease vascular complications
[37]. The S3-THV has a frame geometry that
allows for lower delivery proles and has higher
radial strength when compared to its predecessors
thus allowing improved maintenance of circularity
after it has been deployed [38]. Available sizes
include 20mm, 23mm, 26mm, and 29mm [39].
The 14F and 16F sheaths used with the S3-THV
reduces vascular prole requirements thus allowing more patients to undergo transfemoral TAVI
without signicant access site bleeding or vascular
complications [38].
Evolut Pro andEvolut R (Figs.11 and12)
Currently available in four sizes: 23, 26, 29, and
34 mm allowing for treatment in an annulus
with a perimeter of 56.5–94.2 mm [39]. The
Evolut R is a tricuspid self-expandable valve
with high radial force in the lower part of the
device facilitating self-expansion [39]. The
valve can be recaptured and repositioned and
has a 13mm pericardial skirt at the inow providing additional seal against PVR [39]. Vessel
caliber requirements for access are ≥5mm for
23mm, 26mm, 29mm and ≥5.5mm for 34mm
devices [39].
Specic Considerations
intheSuitability forTAVR andValve
Choice
Severe left ventricular outow tract and annular
calcication: There is an increased risk of PVL
and annular rupture associated with increased
LVOT and annular calcication [40]. Annular
rupture is most frequent during deployment of a
balloon expandable valve or during post dilatation in the setting of PVL [40]. To reduce annular
Fig. 11 Adapted from manufacturer instruction document
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K. Sewnarain et al.
Fig. 12 Adapted from manufacturer instruction document
rupture risk and PVL without the need for post
dilatation, self-expanding expanding valves are
ideal when there is a heavily calcied landing
zone [40].
Preservation of coronary access: In patients
with severe aortic stenosis, the prevalence of coronary artery disease (CAD) is high [40]. A TAVI
valve in which there is easy coronary access is
favored in younger patients and those with existing CAD [40]. Frame mesh density and frame
height are principal factors determining the ease
of coronary access [40]. Although the S3 and
Sapien 3 Ultra extend above the coronary ostia,
they have large upper cells and a low density
mesh allowing for coronary cannulation [40].
Heart Team Decision
The patient was diagnosed with severe, symptomatic, low ow, low gradient aortic stenosis with
preserved ejection fraction requiring aortic valve
replacement, however multiple comorbidities
rendered him high risk for SAVR as determine by
both clinical assessment and calculation of his
Society of Thoracic Surgeons (STS) AVR risk
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