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6—BALLOON AORTIC VALVULOPLASTY 73
Aortic Valve Disease
Tr icuspid Bicuspid Rheumatic
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What has it looked like?
Fig. 6.1 Pathologic appearances of aortic stenosis. In the elderly, the valve is most commonly tricuspid (left
panel). Patients below the age of 65 often have a congenital bicuspid aortic valve (central panel). Rheumatic heart
disease may affect any of the heart valves, including the aortic valve and may result in aortic stenosis (right panel).
BOX 6.1 n AHA Recommendations
IIb C Percutaneous aortic balloon dilatation may be considered as a bridge to surgical AVR or
TAVR for symptomatic patients with severe AS
calcification; however, valve replacement is typically offered as first line. If this is not feasible,
BAV may be considered in the following situations:
n
Young patients with symptomatic AS and peak gradient 50 mmHg
n
Young patients with asymptomatic AS and peak gradient 60 mmHg
n
Young patients with asymptomatic severe AS who are considering pregnancy
Patients With Calcific Degenerative Aortic Stenosis
n
As a palliative procedure for symptomatic benefit (included in European Society of Cardi-
ology [ESC] but not American Heart Association [AHA] guidelines)
n
To facilitate urgent noncardiac surgery (included in ESC but not AHA guidelines)
n
Cardiogenic shock in a patient with severe calcific AS who has been turned down for im-
mediate surgical AVR/TAVR
n
As a trial of therapy in a symptomatic patient with severe AS and other comorbidities that
may cause shortness of breath (e.g., chronic obstructive pulmonary disease [COPD], severe
left ventricular [LV] dysfunction). In this setting BAV may help in deciding whether the
patient’s symptoms are cardiac or noncardiac.
n
As a trial of safety of TAVR therapy in patients with low coronary heights, particularly in
the situation of previous AVR with externally mounted leaflets (e.g., Mitraflow prosthesis)
n
For treatment of large paravalvular leaks after TAVR insertion (usually during the same
procedure as the initial TAVR)
Contraindications to BAV
n
Active endocarditis
n
Moderate or severe aortic regurgitation
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n
Contraindications to systemic heparinization
n
LV thrombus (because LV wire placement is required)
The role of BAV in patients who are currently not suitable for TAVR is growing. Many centers
will consider BAV as a “trial of therapy” where symptomatic benefit from TAVR is uncertain. For
example, patients with poor LV function, where it is unclear if there will be ventricular recovery
after valve replacement, may undergo a BAV and then be reevaluated for suitability for TAVR/
AVR if the LV function or symptoms improve after the BAV. Similarly, in patients with severe
AS and other comorbidities that cause shortness of breath (e.g., COPD), the potential symptomatic benefit, if any, from TAVR is difficult to estimate. In some cases, a therapeutic trial of BAV
may be performed to see if the patient would benefit from TAVR. For timing of such interventions, because the durability of symptomatic improvement after BAV may be short-lived, once
symptomatic benefit is confirmed, TAVR should be performed within 1 to 2 months of the BAV.
Procedural Risks
Procedure risks for BAV are estimated between 4% to 6% in contemporary registries, including
death (estimated at 1%), myocardial infarction (MI), stroke (1% to 2%), vascular damage, cardiac
tamponade, arrhythmia (including need for a permanent pacemaker), and annular rupture/aortic
dissection/ventricular perforation requiring emergency cardiothoracic surgery.
Technique
BALLOON SIZING
Before the procedure, the size of balloon for the valvuloplasty should be selected based on the
results of preprocedural imaging. If cross-sectional computed tomography (CT) has been
performed (e.g., as part of a transcatheter aortic valve implantation [TAVI] workup), the crosssectional area and diameter of the aortic annulus can be measured (Fig. 6.2). If CT is not
available, transthoracic echocardiography (TTE) can be used (Fig. 6.3).
Using TTE, measurements of the aortic annulus should be made in systole in the parasternal
long-axis view. Most operators choose a balloon slightly smaller than the TTE-measured annular
dimension (e.g., a 20-mm balloon for a 22-mm diameter annulus) to reduce the risk of annular
rupture or severe aortic regurgitation (AR) postprocedure. The balloon must always be smaller
than the diameter of the sinotubular junction.
For CT, measurements should also be made in systole. The maximum and minimum diameters of the aortic annulus should be measured from an en-face view of the aortic valve (see
Fig. 6.2). A balloon the same size as the minimal aortic annulus diameter should be used
initially. If the annular shape is very eccentric, an average of the minimal and maximal diameters
may be used to aid balloon sizing (see Figs. 6.2 and 6.3).
Consent and Preplanned Bail-Out Strategy
The patient should be consented for a 5% risk of complications, including death, annular rupture,
stroke, and torrential AR. If surgical rescue would be an option, this should be included in the
consent procedure. The thresholds of escalation in the event of a serious complication (e.g., annular rupture/ventricular perforation) should be determined in advance and agreed with the
cardiothoracic team. It is essential that these considerations are fully discussed with the patient
and family before the procedure. If valve replacement is considered as a bail-out therapy (TAVR/
AVR), suitable personnel and equipment should be available on standby.
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A
B
Fig. 6.2 Computed tomography (CT) sizing of the aortic annulus. If a CT is available, it provides the most
accurate sizing of aortic annular size. Using dedicated CT analysis software, the annular plane is identified on
different cuts of the aortic valve. Cross-sectional area and diameter are measured at that point. The balloon
size selected will either be the same size at the maximum luminal area or slightly smaller (e.g., a 22- or 24-mm
balloon for a 24-mm aortic annulus).
Fig. 6.3 Transthoracic echocardiography sizing of the aortic annulus. A parasternal long-axis view
should be used and careful measurements of the annular dimension obtained during systole.
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During the procedure, rapid pacing is used, and this will require the assistance of a physiologist/
technician. Defibrillator pads should be placed at the start of the procedure as a precaution.
Vascular Access and Temporary Pacemaker Insertion
Sheath size will depend on the choice of balloon, but is typically at least 8F. Ultrasound-guided
access is generally recommended. A closure device (e.g., ProGlide, Angio-Seal) should be considered and, depending on the choice of device, may be deployed at the start of the case. This is
covered in detail in Chapter 2. The side arm of the sheath should be transduced so that systemic
pressure can be monitored during the procedure. Alternatively, a separate radial sheath can be
placed.
Venous access is typically required for temporary pacemaker implantation, even if the patient
has a permanent pacemaker. Pacing during the BAV improves balloon stability and reduces the
likelihood of the balloon prolapsing into the LV or aorta while inflating. Temporary pacemaker
insertion may be via the femoral vein or the internal jugular, depending on the preference and
experience of the operator/department and whether it is anticipated that the temporary wire may
need to remain in situ after the case.
A balloon-tipped flotation temporary pacing wire or a non–balloon-tipped wire may be used.
In elderly patients with severe AS, we would suggest consideration of a balloon-tipped pacing
wire, if available, to reduce the risk of pericardial tamponade. If the patient has a permanent
pacemaker, rapid pacing may be performed via the device, but this should be checked in advance,
as not all devices will be able to pace to the ventricular rates required for BAV.
Procedural Steps
Once vascular access is secured, the patient should be heparinized. Seventy-five to 100 units/kg
of intravenous heparin should be given, aiming for an activated coagulation time (ACT) of 250
to 300 seconds. A pigtail catheter (usually 6F) may be used to perform aortic angiography; alternatively, echocardiographic assessment is used, particularly in those patients with some degree of
renal function impairment. If angiography is performed, typically a projection of left anterior
oblique (LAO) 10 to 20 degrees is optimal.
For crossing the aortic valve, several approaches are available. We typically use a 6F diagnostic
AL1 catheter, which is advanced on a soft, J-tipped 0.350 wire under fluoroscopic guidance into
the aortic root. Next, the J-wire is exchanged for a soft, straight-tipped 0.350 wire. The AL1
catheter is gently angled clockwise and counterclockwise, fanning across the aortic root. The
straight-tipped wire is advanced into and out of the aortic root. The movement of the tip of the
wire guides the operator in the next movement of the wire: if the wire curls to the right, it is likely
in the right coronary sinus, and the catheter should be angled more towards the left. If the wire
curls to the left, it is in the left sinus and the catheter should be angled to the right (Fig. 6.4).
Once the valve is crossed, an exchange length wire may be used to exchange for a pigtail in
the LV. Simultaneous LV/aortic (with a dual lumen pigtail) or LV/femoral artery (transducing
the side arm of the sheath) pressures can be measured, confirming that the AS is severe and allowing comparison of pre- and post-BAV hemodynamics (see Fig. 6.4).
An AL2, JR4, or multipurpose catheter may be preferred if there is a horizontal aortic route
or if the AL1 is not successful.
Once the straight wire passes into the left ventricle, the fluoroscopic angle should be
changed to 30 degrees right anterior oblique (RAO), a view that displays the LV in a long-axis
projection. The wire is carefully advanced, and the AL1 catheter then advanced over the
straight wire into the LV. The AL1 catheter should ideally retroflex so its tip is away from the
LV apex (Fig. 6.5).
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Fig. 6.4 Crossing a severely stenosed aortic valve using an AL1 catheter and a straight-tipped wire.
The wire will bend into the coronary sinuses, giving an indication of where the orifice lies and where to next
angle the catheter.
Fig. 6.5 The straight-tipped wire should be advanced into the left ventricle under fluoroscopic guid-
ance in a right anterior oblique (RAO) 30-degree projection to open out the left ventricle. The AL1
catheter should then be carefully advanced into the left ventricle, allowing exchange for a stiff wire.
If the wire and catheter cannot be guided into the LV apex, the wire may have passed through
the mitral valve apparatus. Echocardiographic assessment can be helpful in this regard to document position. If this is the case, the wire is often skewed to one side and the catheter will not sit
easily in the ventricular apex. Usually this is best dealt with by crossing the valve again for a better position; however, you can first attempt to rescue the position by pulling back the catheter
slightly and using an exchange length wire to switch out for a pigtail catheter, which is less likely
to become entangled in the mitral valve apparatus.
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Once the pigtail (if simultaneous pressures have been measured) or AL1 catheter has been
advanced into the LV, it may be used to exchange for a stiff wire. Commercially available wires
with preformed ventricular curves include the Lunderquist double curved wire (Cook Medical),
the Safari (Boston Scientific), and the Confida (Medtronic) wire. Each has a softer, curved ventricular tip that sits in the LV. The rest of the wire is stiff, allowing equipment, including balloons
and TAVR delivery systems, to be navigated through the aorta and through the aortic valve.
Insertion of the Valvuloplasty Balloon
For BAV, the balloon is advanced over the stiff wire, with direct visualization of the wire in the
LV during balloon insertion. The ventricle has a predisposition to “kick out” equipment that has
been positioned there, so the wire should be held at all times and the LV kept in view fluoroscopically while the balloon is advanced.
Once the balloon is in the aortic root (but not yet across the valve), the team should prepare
for the valvuloplasty. The temporary pacing should be set, ready to pace at a fast ventricular rate
(usually between 140 and 200 beats per minute [bpm]), such that it reduces the systemic pressure
to approximately 40 mmHg during rapid pacing. Lower pacing rates should be considered in the
case of severe LV dysfunction or low baseline blood pressure, or if atrioventricular (AV) block
occurs at the higher rates. If the procedure has been prolonged or there is any question of the
temporary pacemaker position, the pacing wire should be retested before BAV. Rapid pacing runs
should be performed for the shortest possible duration to limit ischemia.
Next, the balloon is advanced across the AV in an anteroposterior (AP) or LAO 10- to 20-degree
view. It should sit with approximately half of the balloon on the ventricular side and half on the
aortic side. In heavily calcified valves, this is judged using the line of valvular calcification as a marker.
In less calcified valves, a pigtail may be placed in the non- or right coronary cusp to mark the level
of the aortic valve (Fig. 6.6 and Fig. 6.7).
Choice of Valvuloplasty Balloon
Before the start of the procedure, the aortic annulus measurements either by TTE or CT should
have been assessed, as described earlier. Balloon diameters used are typically between 18 and
Fig. 6.6 Positioning of the balloon across the aortic valve (left panel) and balloon inflation (right panel).
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Fig. 6.7 Fluoroscopic imaging of a balloon inflated across the aortic valve. Here a pigtail catheter has
been used to mark the aortic root, and it can be seen that the balloon is positioned too high into the aorta.
During inflation, this reduces balloon stability, and the balloon prolapsed into the aorta. The balloon was
therefore deflated and repositioned so it was halfway across the annular plane and then reinflated.
26 mm in diameter and 30 to 60 mm in length. The balloon is prepared by deairing and filling
with a saline/contrast mix. The saline:contrast ratio used is more dilute than that of coronary
balloons and should be four parts saline to one part contrast to enable rapid inflation and deflation of the larger balloon.
Aortic balloons may be semi- or noncompliant, and inflation pressures and volumes will be
set by the individual manufacturer. The Tyshak II (Braun International Systems) is an example
of a semi-compliant balloon, whereas the Z-Med (Braun International) and Maxi LD Balloons
(Cordis) are noncompliant, with higher-rated burst pressures. We typically start with a semicompliant balloon because this is lower profile (fits through an 8F sheath). More recent balloon
designs have a tapered waist, designed to improve balloon stability during inflation. Examples
include the NuCLEUS (NuMed) and V8 (InterValve) balloons.
Once the balloon position is correct, the balloon is inflated during rapid ventricular pacing.
The process is as follows:
1. Pacing on—Ensure pacing has captured and aortic pressure has fallen to ≈ 40 mmHg
2. Balloon inflation—Rapidly inflate the balloon and then remain inflated for approximately
2 to 3 seconds
3. Balloon deflation
4. Pacing off—Set temporary pacing to a backup rate of 40 bpm
It is important that a balloon is not left inflated while the heart contracts normally because
this will cause the balloon to either dive into the LV or be ejected into the aorta.
If the balloon prolapses forward or backward during inflation, ensure that the pacing has
captured and pressure has dropped before inflating. If this does not work, try pacing at a rate
20 bpm higher than the previous rate.
Once an effective balloon inflation has been delivered, the balloon should be withdrawn into
the descending aorta and TTE performed to assess if there is any AR and if there has been a
reduction in gradient through the AV. If there is no AR and the gradient through the AV has not
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reduced, a further inflation should be performed. A balloon 2 mm greater in diameter may be
selected if the first balloon choice was sized less than 1:1 to the aortic annulus diameter.
Final hemodynamics may be measured via reinsertion of the pigtail catheter using the ex-
change length wire. A successful valvuloplasty is typically defined as a 40% reduction in aortic
gradient with no significant AR; however, this is often not possible to achieve, because larger
balloons will reduce the gradient but risk significant AR. It is therefore reasonable to stop if the
degree of baseline AR worsens.
Continuous hemodynamic monitoring during the procedure via the femoral sheath is ex-
tremely helpful, because a reduction in the diastolic pressure in the aorta/peripheral circulation
suggests significant AR may have occurred.
Risk of Heart Block Post-BAV
At the end of the procedure, it is important to evaluate the electrocardiogram (ECG)—in particular, if there has been a change in the PR or QRS intervals and if any heart block has been
present during the procedure. If the transient heart block has occurred, the temporary pacing wire
may be best left in situ. Commonly the QRS may widen; however, if there are no other signs of
conduction problems, the temporary wire can be removed and the patient monitored for any
heart block over the next 24 to 48 hours.
Summary and Take-Home Messages
n
BAV may be performed for severe AS in patients with congenital bicuspid AS.
n
In patients with degenerative calcific AS, BAV may be used as a bridge to TAVR/SAVR, as
a trial of therapy, or for palliation of symptoms.
n
Procedural risks are 4% to 6% even with contemporary equipment, including a 1% risk of
stroke or death.
n
Careful balloon sizing using preprocedure TTE or CT is important.
n
The bail-out strategy (if any) should be determined in advance and agreed with the cardio-
thoracic team if bail-out TAVR/AVR is an option.
References
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. Keeble TR, Khokhar A, Akhtar MM, Mathur A, Weerackody R, Kennon S. Percutaneous balloon aortic
valvuloplasty in the era of transcatheter aortic valve implantation: a narrative review. Open Heart.
2016;3(2):e000421.
3. Elmariah S, Arzamendi D, Palacios IF. Balloon aortic valvuloplasty in the transcatheter aortic valve
replacement era. Interv Cardiol Clin. 2012;1(1):129-137. doi: 10.1016/j.iccl.2011.11.001.
e1
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Abstract: Balloon aortic valvuloplasty (BAV) is designed to fissure or fracture the calcified aortic
valve and separate fused commissures. The role of BAV depends on the specific clinical setting.
It may be used as a definitive therapy in patients with severe aortic stenosis with a congenital
bicuspid valve. It may be used as a bridge to transcatheter or surgical aortic valve replacement in
degenerative calcific aortic stenosis. Even with contemporary equipment, procedural risks remain
at approximately 5%.
Keywords: balloon aortic valvuloplasty, valvuloplasty, aortic stenosis
CHAPTER 7
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Transcatheter Aortic Valve
Implantation: Work up and
Indications for Intervention
Claire E. Raphael Abdallah El Sabbagh Charanjit Rihal
Background
Aortic stenosis is the most common valvular heart disease in the elderly population, with a
prevalence of approximately 3% in patients over 75 years old. The prognosis of symptomatic severe aortic stenosis is poor, with a 50% mortality rate at 2 years; therefore valve replacement is
usually recommended once symptoms of shortness of breath, heart failure, or angina occur.
In the majority of patients, the aortic valve is trileaflet. Patients with severe aortic stenosis
below the age of 65 usually have a congenital bicuspid aortic valve. In both cases, the aortic valve
becomes progressively calcified with age and leaflet movement is restricted.
TAVR for Aortic Stenosis
Transcatheter aortic valve replacement (TAVR) has emerged as an alternative to surgical aortic
valve replacement (SAVR) in patients with severe symptomatic aortic stenosis. The last decade has
seen a steep rise in the number of TAVR procedures performed, as well as improvements in valve
design, technology, and procedural techniques.
Decisions regarding the type of valve and approach to valve implantation are best made
through a heart valve team and performed in a center with appropriate experience and infrastructure. In low-risk patients, the current American Heart Association/American College of
Cardiology (AHA/ACC) guidelines recommend SAVR via a midline sternotomy. Patients at
high and intermediate risk may have TAVR recommended (Box 7.1). TAVR in low-risk
patients is feasible, but requires further data on prosthesis durability before it is offered in
younger patients.
Assessment and Risk Stratification of Patients
The Society of Thoracic Surgeons (STS) score and other factors may be used to stratify patients
into low, intermediate, and high risk (Table 7.1). The STS score is based on age, gender, comor-
bidities (including hypertension, peripheral arterial disease, cerebrovascular disease, diabetes, and
lung disease), and immediate preoperative condition (including presence of cardiogenic shock
and whether the patient currently has heart failure). Scores are best assessed using the online
calculator found at http://riskcalc.sts.org/stswebriskcalc/. The Euroscore uses similar criteria and
is found at http://www.euroscore.org.
Other risk factors may make patients high risk for SAVR despite a low STS score. These
would include prior chest radiation, porcelain aorta, and previous coronary artery bypass graft
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