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82 2—AORTIC VALVE INTERVENTIONS
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BOX 7.1 n AHA Guidelines
I C For patients considered for TAVR, a heart valve team, including experts in valvular
heart disease, cardiac imaging, interventional cardiology, cardiac anesthesia, and
cardiac surgery, should collaborate to provide optimal patient care
I A SAVR or TAVR is recommended for symptomatic patients with severe aortic stenosis
(AS) and high risk for SAVR, depending on patient-specific procedural risks, values,
and preferences
I A TAVR is recommended for symptomatic patients with severe AS and a prohibitive risk
for SAVR who have a predicted post-TAVR survival greater than 12 months
IIa B-R TAVR is a reasonable alternative to SAVR for symptomatic patients with severe AS
and an intermediate surgical risk, depending on patient-specific procedural risks,
values, and preferences
III B
TAVR is not recommended in patients in whom existing comorbidities would preclude
the expected benefit from correction of AS
TABLE 7.1 n Assessment of Procedural Risk for TAVR
Low risk
Intermediate risk
High risk
Prohibitive risk
n
STS-PROM ,4%
n
No frailty
n
No comorbidities
n
No procedure-specific impediments
n
STS-PROM 4%-8%
n
Mild frailty
n
One major organ system compromise not to be improved postoperatively
n
A possible procedure-specific impediment
n
STS- PROM .8%
n
Moderate-severe frailty or .2 major organ system compromise not to be
improved postoperatively
n
A possible procedure-specific impediment
n
STS PROM .50% at 1 year
n
3 major organ compromise not to be improved postoperatively
n
Severe frailty
n
Severe procedure specific-impediments
From Otto CM et al 2017 ACC Expert Consensus Decision Pathway for TAVR JACC 2017. STS PROM: Society
of Thoracic Surgeons Predicted risk of mortality
(CABG) with patent grafts. These patients may be offered TAVR if the heart team consider this
to be the optimal strategy.
Contraindications to TAVR
n
Active endocarditis
n
Patient with poor life expectancy or comorbidities that would preclude likely benefit from
a valve-in-valve TAVR procedure
n
Anatomic unsuitability for either self-expanding or balloon-expandable prosthesis (covered
in the following chapters), for example, aortic annulus too large for largest currently available
valves
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Workup for Transcatheter Aortic Valve Replacement
The initial workup for TAVR requires a full history and clinical examination to determine if the
patient is symptomatic and that the aortic stenosis is severe. Transthoracic echocardiogram
(TTE) will determine the severity of aortic stenosis, the presence of any coexistent disease in the
other valves, and the left ventricular function.
Once it is confirmed that the patient has severe aortic stenosis, further specific diagnostic
testing is indicated. Patients require assessment of their coronary arteries, which is usually via
invasive coronary angiogram, but may be performed using computed tomography (CT) if the
pretest probability of coronary artery disease is low. Pulmonary function tests and carotid Dopplers are usually performed as part of preprocedure risk assessment, particularly if SAVR is being
considered.
If TAVR is planned, patients should have imaging to assess the size of the aortic annulus and
likely access routes. This is usually achieved via CT of the chest/abdomen and pelvis with a contrast aortogram. Measurement of the annulus is important for sizing of the prosthesis, and this is
detailed in the following chapters specific to current balloon-expandable and self-expanding
valves, respectively.
The majority of TAVRs are performed using the transfemoral route. Subclavian, direct aortic, and
transapical are alternative access routes when transfemoral is not suitable, and these are described in
detail in Chapter 11. Transfemoral access and closure are described in Chapter 2.
Coronary Angiography
Coronary angiography is performed to rule out severe coronary artery disease that may lead to
hemodynamic compromise during the procedure if revascularization is not performed. Currently
the guidelines recommend performance of revascularization of severe coronary stenosis (.70%)
involving the proximal portion of the large epicardial vessels, such as the proximal left anterior
descending (LAD) or right coronary artery (RCA). Stenoses involving side branches are usually
deferred, as they are less likely to cause hemodynamic compromise. If percutaneous coronary
intervention (PCI) is required, the use of drug-eluting stents is preferable to bare metal stents,
especially if the patient is a transfemoral TAVR candidate.
Hemodynamic assessment of aortic stenosis may be performed at the time of coronary angiography, although this is usually not required if the TTE data are clear-cut. Common indications
for hemodynamic assessment include determination of severity of aortic stenosis in cases where
there is a discrepancy between echo data and clinical presentation and to obtain accurate assessment of right heart and pulmonary artery pressures in patients with heart failure and significant
pulmonary hypertension.
Computed Tomographic Scan
ASSESSMENT OF ACCESS ROUTES FOR TAVR
CT provides detailed anatomic assessment of the aortic valve, aortic root, and aorta overall and
provides anatomy of the lower extremities (iliofemoral system), including vessel caliber, tortuosity,
location and extent of calcification, and presence of any aneurysms or thrombus within the arterial
system. Fig. 7.1 demonstrates CT analysis of the iliofemoral arteries. It also shows the presence of
a moderate-sized infrarenal aortic aneurysm with organized intramural thrombus. Measurements
are performed along the diameter of the common femoral, external iliac, common iliac, and abdominal aorta on a double-oblique axis using reformatted images and by measuring minimal
luminal diameters, excluding the calcified portions.
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Fig. 7.1 CT analysis of the iliofemoral arteries.
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Evaluation of anterior calcification is performed by looking at the axial cross-sectional images
at the level of the femoral head. Presence of anterior calcium in the common femoral artery at
the level of the femoral head may preclude use of a Perclose device and increase the risk of vascular complications. If calcification is dense and there are no “soft spots” for device closure, this
would be an indication to proceed with alternative access.
The CT also allows assessment of tortuosity across the path of the valve from the common
femoral artery up to the aortic root. Often the tortuosity straightens when a stiff wire is used
during the procedure, and this can be evaluated at the time of coronary angiography if this is a
concern: coronary angiography is performed through the femoral approach, and a stiff wire is
introduced to see if the tortuosity straightens up with the wire. If it does, a transfemoral TAVR
is likely feasible. If it does not, alternative access may be considered.
Finally, in cases where embolic protection devices are planned, the origin of the right brachiocephalic artery and the left common carotid artery should be assessed to make sure no significant
plaque is present.
Assessment and Sizing of the Aortic Annulus
The orientation of the ascending aorta, presence and extent of calcification on the aortic valve
leaflets, position and height of the coronary arteries relative to the aortic annulus, dimensions of
the aortic annulus and ascending aorta, size of the aortic sinuses, and presence or absence of
calcification extending into the left ventricular outflow tract (LVOT) are best assessed on the
TAVR CT.
Aortic Root
Sizing of the TAVR device is dependent on which device is chosen, and details are given separately in the chapters for self-expanding and balloon-expanding prostheses. Devices are sized
using either the annular area or perimeter, so both are typically measured during CT analysis.
Measurements of the sinus of Valsalva diameter and coronary heights will guide the choice of
valve and inform procedural risks if there are low coronary heights.
Risk of coronary artery obstruction, by displacing a calcified leaflet or by prosthetic leaflet
eclipse, is increased when the coronary height, measured from the annulus to the origin of the
left or right coronary artery on the cardiac computed tomography angiography (CTA), is less
than 10 mm and/or the sinus of Valsalva diameter is less than 28 mm on average. If coronary
heights are low and the patient is of low or intermediate risk, this favors SAVR over TAVR.
Aortic root orientation: The CTA provides the coplanar angle, which is the fluoroscopic
angle at which the noncoronary right and left cusp are aligned. This is important for valve positioning and deployment. Horizontal aortic roots are less favorable for self-expanding valves because the delivery sheath can bias one side of the aortic wall, which would make it difficult to
position and deploy the valve coaxially. In this case, a balloon-expandable valve is usually more
suitable. Although an angle is measured on CT, the stiff wire may change the orientation of the
aortic root during the procedure, and so the angle may need to be modified to line up the cusps
at the time of the TAVR procedure.
Aortic leaflet/LVOT calcification: Presence of heavy calcification in the leaflets and/or
LVOT is a risk factor for paravalvular leak, annular rupture, and heart block. If this is a concern,
a self-expanding valve may be selected rather than a balloon-expandable valve to reduce the risk
of annular rupture during valve deployment. Care should be taken if a self-expanding valve is
used, particularly if predilation or postdilation of the valve is required.
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Deciding on TAVR
Once the patient has completed the workup, they should be discussed in an appropriate multidisciplinary environment with the following specific questions:
1. Do they have severe symptomatic aortic stenosis?
2. Are they best managed with SAVR, TAVR, or medical management?
3. If they are suitable for TAVR:
a. What is the most appropriate first-line access route?
b. Which valve or valves are anatomically suitable?
c. Should the procedure be under local anesthesia with conscious sedation, or are there
patient or procedural factors that favor general anesthesia?
Anesthesia and Procedural Medications
TAVR can be performed using general anesthesia or conscious sedation with analgesia using
moderate anesthesia care (MAC). MAC is preferred for straightforward transfemoral TAVR, as
it avoids intubation and speeds up patient recovery and mobilization. General anesthesia is used
and recommended in situations where the patient may need a deeper level of sedation and analgesia; where airway compromise may be an issue; where an alternative access TAVR route is
employed, like subclavian or transaortic access; and situations where patients cannot cooperate
with conscious sedation.
TAVR: PROCEDURAL AND POSTPROCEDURAL MEDICATIONS
Procedural medications include perioperative antibiotics as dictated by local practice (typically a dose of a broad-spectrum antibiotic at the time of TAVR and two subsequent doses
after).
Most centers will advocate the use of two antiplatelet/anticoagulant agents postprocedure for
at least 3 months. Our institution uses aspirin and warfarin for 3 months followed by lifelong
aspirin to minimize the risk of valvular thrombosis. Other institutions may use a dual antiplatelet
regimen similar to that used post-PCI. Recommendations regarding optimal anticoagulation
strategy post-TAVR are not yet established.
Consent for TAVR
Consent for TAVR includes the risk of death, disabling stroke, and major vascular damage.
The risks for an individual patient will depend on their age, comorbidities, and anatomic
factors, including vascular size and calcification. We quote a risk of these complications
of approximately 5%. Approximately 10% of patients will require a permanent pacemaker
after TAVR, and this risk is greater if there are preexisting conduction abnormalities on the
electrocardiogram (ECG). Patients should give consent for immediate implantation of a
pacemaker in case the procedure results in complete heart block with no escape rhythm.
Bailout procedures should be discussed with patients in advance, including whether emergency open aortic valve replacement (AVR) would be suitable in the event of annular rupture
or TAVR prosthesis failure.
The next two chapters describe procedural details and workup for balloon-expandable and
self-expanding valves.
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Further Reading
1. Otto CM, Prendergast B. Aortic-valve stenosis — from patients at risk to severe valve obstruction. N Engl
J Med. 2014;371(8):744-756.
2. Otto CM, Kumbhani DJ, Alexander KP, et al. 2017 ACC expert consensus decision pathway for trans-
catheter aortic valve replacement in the management of adults with aortic stenosis: a report of the
American College of Cardiology Task Force on Clinical Expert Consensus Documents. J Am Coll Cardiol.
2017;69:1313-1346.
CHAPTER 8
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Balloon Expandable Transcatheter
Aortic Valve Replacement
Oluseun Alli Rajiv Gulati
Introduction
The only balloon-expandable valve currently on the market is the Edward Sapien Heart valve
manufactured by Edwards Life Sciences. This chapter will focus on the procedural techniques
involved in the use of this balloon-expandable prosthesis.
Edwards Sapien Balloon-Expandable Heart Valve
Prosthesis
The Edwards Sapien heart valve system is made up of a cobalt–chromium frame with three
bovine pericardial leaflets. The frame has open upper and closed lower cells to enhance geometry
and ensure an ultra-low-profile delivery, and also has a skirt incorporated at its inflow portion and
outer sealing skirt to reduce paravalvular leaks. The current valve, Sapien 3, is delivered via the
Edwards Commander delivery system for a transfemoral approach. This is a 14-16F eSheath
compatible system with optimal positional control, and its dual articulation enables coaxiality and
fine control of valve positioning. The transapical approach typically uses the 18F Edwards Certitude delivery system, and this has an integrated pusher to streamline the procedure and an ergonomically designed handle for ease of use (Fig. 8.1).
Edwards S3 Valve
The valve is simple to deploy and has shown good durability and function in both trial and realworld experience. The valve comes in four sizes: 20 mm, 23 mm, 26 mm, and 29 mm, suitable
for most annular dimensions. The delivery sheath can be actively flexed, and this is beneficial,
particularly in horizontal aortas.
Patient Selection
There are several important considerations when choosing the balloon-expandable transcatheter
aortic valve replacement (TAVR) system over a self-expanding system. First, the current S3 system requires 16F transfemoral access. Some of the self-expanding prostheses, including the
Evolut R, use an in-line sheath, which requires 14F access and may be more suitable for patients
with smaller iliofemoral or alternative access sites. The minimal vessel dimensions are detailed
later. The sheath can be actively flexed when it is advanced, and this is particularly useful in the
case of horizontal aortas.
Second, the balloon-expandable TAVR requires rapid ventricular pacing during valve deploy-
ment. A short pacing run is required and is well tolerated by the majority of patients; however,
88
8—BALLOON EXPANDABLE TRANSCATHETER AORTIC VALVE REPLACEMENT 89
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AB
Fig. 8.1 Computed tomography imaging obtained before transcatheter aortic valve replacement. (A) Shows
a normal 3D CT angiogram; (B) and (C) show a patient with a moderate-sized infrarenal abdominal aortic
aneurysm (arrows).
patients with very poor left ventricular (LV) function or significant pulmonary hypertension may
not tolerate rapid pacing well. These patients may therefore be more suited to a self-expanding
valve.
Finally, the Edwards S3 has leaflets at the annular position and so has a smaller effective
orifice area than supra-annular valve designs such as the CoreValve. For larger valves, this
is less important, as postoperative gradients will be low, but in patients with small annular
dimensions, particularly in the case of valve-in-valve TAVR, a supra-annular valve may be
more suitable. In practice, postprocedure transaortic gradients using the Edwards S3 valve
are low, so this is more of a theoretic than a practical concern in the vast majority of
patients.
C
CT Assessment of Access Routes for TAVR With the
Edwards S3
The current Edwards Sapien 3 prosthesis requires a minimum of 5.5 mm for the 14F sheath and
6 mm for the 16F sheath in a relatively noncalcified and compliant vessel. If there is evidence of
severe concentric calcification, then the minimum diameters will need to be at least 0.5 to 1 mm
larger than those previously noted to help prevent vascular complications.
Valve Sizing of Edwards S3 on CT
The Edwards S3 is sized based on the aortic area of the native aortic annulus measured on computed tomography (CT). The annular area may be measured on transesophageal echocardiogram
(TEE) as an alternative; however, CT is preferred as a first-line option where possible. There are
four sizes of the S3 valve: 20 mm, 23 mm, 29 mm, and 29 mm. There is some overlap in native
annular areas that are suitable for valves of adjacent size (Table 8.1). In our institution, for native
annular areas close to the cutoff between two valve sizes, we tend to choose the larger valve and
remove 1 cc of contrast from the inflation balloon. Manufacturer recommendations for a smaller
valve are considered if there is severe calcification of the aortic annulus, a narrow root, and
low coronary ostia (to reduce the risk of coronary obstruction); a narrow sinotubular junction; a
porcelain aorta; or significant mitral annular calcification.
90 2—AORTIC VALVE INTERVENTIONS
Step 1:
sheath inser
Step 2:
sutures and upsiz
main access site
to 8
f
in the 6
and pacemak
in the 6
Step 4:
angiograph
up accurate
coplanar angle
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TABLE 8.1 n Sizing Chart for Edwards S3
20 mm 273-345
23 mm 338-430
26 mm 430-546
29 mm 540-683
Procedure
The TAVR access site is chosen based on a review of CT and preprocedural assessment. The
radial artery or contralateral access site is accessed under ultrasound guidance, and 5 or 6F
arterial and venous sheaths are placed for the pigtail catheter and the temporary pacing wire.
The TAVR access site is also punctured under ultrasound guidance and preclosure sutures are
deployed after placement of a 6F sheath (Fig. 8.2). This is ultimately upsized to a 14 or 16
F Edwards sheath.
Access and
tion
Perclose
Fr sheath
ollowed by pigtail
Fr artery
er
Fr vein
Coplanar
y to set
6 Fr
e
8 Fr + 2
Perclose sutures
Fig. 8.2 Initial procedural steps.
Pacemaker
6 Fr 6 Fr
6 Fr +
6 Fr +
Pigtail
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Initial Procedural Steps
See Fig. 8.2.
1. Access is obtained with 6F sheaths in the bilateral common femoral artery (or one in radial
artery) and one in the femoral vein.
2. At the site of the transcatheter valve insertion, the 6F sheath is removed and two Perclose
sutures are deployed using a preclosure technique at 10 o’clock and 2 o’clock, and the
sheath is then upsized to 8F.
3. A balloon-tipped pacemaker catheter is then placed in the femoral vein and positioned in
the right ventricle. It is then tested at 80 beats per minute (bpm).
4. A 5F pigtail is then positioned in the noncoronary cusp, and an aortogram is performed at
the prespecified angle suggested by CT to confirm the presence of coplanar alignment of
the three cusps of the aortic valve.
Aortic Angiography
Aortic angiography is performed using predetermined coplanar angles obtained via preprocedural CT.
If the angle is not accurate, the image intensifier is moved cranial or caudal or left anterior oblique
(LAO) or right anterior oblique (RAO) projection to find the best projection. Ten to 30 cc of contrast
is usually adequate for aortic angiography, and the contrast may be diluted (e.g., 30 mL of 50%
contrast) to reduce the total procedural contrast load.
Insertion of the Edwards eSheath
The 6F sheath is removed and then a stiff Amplatz wire or similar is advanced into the aorta and
the iliofemoral system, dilated with the accompanying dilator, and the sheath inserted. It is important to observe the sheath under fluoroscopy as it is inserted to ensure smooth advance into
the vessel. Once the sheath is in, it may be sutured in place and flushed, and heparin is administered to achieve a therapeutic activated clotting time (ACT) .250 sec.
Next, the aortic valve is crossed. We typically use an AL1 catheter and a 0.0359 straight wire
in the LAO view or CT-specified coplanar angle. Movement of the catheter clockwise or
counterclockwise and gentle probing of the aortic valve with the straight wire is performed as
per the methods for balloon aortic valvuloplasty (BAV ). Once the straight wire has crossed the
aortic valve, the AL1 is advanced into the LV toward the apex with the tip pointing upward.
The straight wire is then removed and exchanged for a preshaped LV curve stiff wire. There
are now several options for the LV curve stiff wire: a 0.0359 stiff Amplatz wire can be shaped
by the operator to form an atraumatic curve at the tip. We prefer to use commercially available
preformed wires, such as the Safari wire (Boston Scientific), Confida (Medtronic) wire, or
Lunderquist wire (Cook Medical), which are manufactured with an LV curve and come in
different sizes.
Balloon Aortic Valvuloplasty
BAV may be performed before valve placement and deployment. It is recommended to consider
valvuloplasty in critical aortic stenosis so as to allow for easy crossing of the new valve. BAV may
be skipped if the valve is not very tight or if there is concomitant moderate or greater aortic insufficiency. BAV is performed using the Retroflex balloons with 18 mm, 20 mm, 23 mm, and 25 mm
used for 20 mm, 23 mm, 26 mm, and 29 mm TAVR valves, respectively. The valvuloplasty balloon
is advanced and positioned across the aortic valve, and valvuloplasty is performed under rapid
ventricular pacing, usually at 180 bpm. The new valve must be ready or near-ready before
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