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230
Key Questions in CONGENITAL CARDIAC SURGERY
In the United States, currently only the Abbott Amplatzer™ Septal
Occluder and the GORE®Septal Occluder are approved for
secundum ASD closure.
20 What are the indications for Fontan fenestration
closure?
The strategy of creating a right-to-left shunt decompression valve in
•
the Fontan circuit during all Fontan completion procedures is
favoured in some centres, as it allows the venous pressures to be
reduced and it can help to prevent hepatic ischaemia by pressure
overload, leading to portal hypertension, cirrhosis and protein-losing
enteropathy.
In patients with borderline physiology or anatomy, such as diminished
•
ventricular function, pulmonary artery lesions, elevated pulmonary
vascular resistance, the presence of a fenestration is deemed
necessary by most.
The beneficial effects of a fenestration are, however, obtained at the
•
expense of lower systemic oxygen saturations. Chronic desaturation
can become a significant burden and lead to important
complications.
A thorough haemodynamic evaluation should be performed before
•
attempting to close the fenestration in the catheterisation laboratory.
AB
*
*
Figure 17. Angiographic images demonstrating: A) a patent Fontan
fenestration with important shunt flow in the extracardiac conduit (arrow) and
a narrow right pulmonary artery; and B) closure of the fenestration with an
Amplatzer™ device (white arrow) and stent placement (red arrow) in the right
pulmonary artery to allow better pulmonary run-off. The right atrial wall can
also be seen (asterisks).
6 Congenital angiography and catheter interventions
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
It is reasonable to consider transcatheter closure of a Fontan
•
fenestration in patients with favourable haemodynamic status.
These can be demonstrated with a temporary balloon occlusion of
the fenestration, if the systemic oxygen saturation improves with
only a modest rise in Fontan pressure or a fall in cardiac output
<20%.
Fenestrations may be closed using an ASD occluder (Figure 17),
•
PFO occluder, VSD occluder, vascular plug or covered stent
(Figure 18). The type of device chosen may be influenced by the
type of Fontan operation, patient size, specifics of the anatomy and
operator preference.
AB
*
231
Figure 18. Angiographic images demonstrating: A) a patent Fontan
fenestration with important shunt flow across a previously stented fenestration
in the extracardiac conduit (arrow), a narrow left pulmonary artery that has
been previously stented (asterisk) and several collateral vessels coiled; and
B) closure of the fenestration with a covered CP stent (arrow).
21 What are the principles of transcatheter closure of a
ventricular septal defect?
Although ventricular septal defect (VSD) is the commonest congenital
•
heart defect and accounts for 25% of all defects, it is one of the rarer
interventions in most countries.
Interventional closure has been performed as an alternative to surgery
•
in selected native or residual perimembranous and muscular defects.
Percutaneous VSD device closure is recommended in patients with a
•
haemodynamically significant VSD, which is defined as having
232
Key Questions in CONGENITAL CARDIAC SURGERY
evidence of left-sided heart volume overload, heart failure or elevation
of right-sided heart pressures secondary to left-to-right shunting. In
some countries, small defects are closed for cultural and social
reasons.
For small infants who weigh <5kg or for patients with abnormal septal
•
wall planes, percutaneous closure carries additional risk beyond the
procedure and device-related adverse events.
Other contraindications for transcatheter VSD closure include:
•
a) pulmonary vascular disease (>7 Wood Units m2);
b) sepsis;
c) contraindications for antiplatelet therapy;
d) defects associated with other cardiac lesions requiring surgery.
The perimembranous septum is close to vital structures of the aortic
•
valve, atrioventricular conduction tissue and the tricuspid valve. The
vast majority of symptomatic infants have a VSD with dimensions that
preclude safe interventional closure. Notwithstanding the general risks
of catheter manipulation and device embolisation, both heart block and
damage to the aortic and tricuspid valves remain serious
complications.
A number of devices (Figure 19) have been used for VSD closure,
•
including:
ABC
Figure 19. Devices used for closure of a ventricular septal defect,
including: A) Amplatzer™ Muscular VSD Occluder; B) Amplatzer™
Membranous VSD Occluder; and C) Amplatzer™ Duct Occluder II.
Reproduced with permission from Abbott.
6 Congenital angiography and catheter interventions
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a) Amplatzer™ Muscular VSD Occluder (Figure 20) — which is a
self-expandable device made of nitinol wires, consisting of two
flat discs having a diameter 8mm larger than a central
connecting waist (7mm long). The diameter of the waist
determines the size of the device. The device needs a delivery
sheath ranging from 6 to 9Fr in size;
AB
Ao
LV
IVS
LV
Figure 20. Angiographic images demonstrating closure of a muscular
ventricular septal defect (VSD): A) retrograde left ventricular injection via the
aortic valve demonstrating a large shunt to the right (arrow); and B)
retrograde left ventricular injection via the aortic valve demonstrating closure
of the defect with an occluding Amplatzer™ Muscular VSD Occluder (arrow)
and interruption of shunt flow. Ao = aorta; LV = left ventricle; IVS =
interventricular septum.
b) Amplatzer™ Membranous VSD Occluder — which consists of
two discs of unequal size. The device is available in sizes from
4 to 18mm and requires delivery sheaths from 7 to 9Fr;
c) Amplatzer™ Duct Occluder II.
233
22 What are the principles of hybrid closure of a
ventricular septal defect?
The hybrid approach for VSD closure in children is a possible
•
alternative to standard surgery, when CPB is contraindicated or its
repair presents some specific challenges. It is used successfully in
post-infarction communications in adults.
Hybrid VSD closure is performed under general anaesthesia, via a
•
median sternotomy.
234
Key Questions in CONGENITAL CARDIAC SURGERY
It can be performed in the catheterisation laboratory, hybrid
•
laboratory or surgical theatre (Figure 21), although the latter makes
the use of fluoroscopy more difficult. It is generally performed on a
beating heart without the use of CPB.
AB
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sp
f
os
C
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Figure 21. Closure of a mid-septum muscular ventricular septal defect (VSD)
using a hybrid approach: A) measurements of the VSD are obtained with
transoesophageal or epicardial echocardiography to find an optimal
puncture point on the right ventricular free wall; B) following a median
sternotomy and securing of cannulation sites, a guidewire is passed through
the right ventricular (RV) anterior wall and the target muscular VSD into the left
ventricle (LV). A sheath is then inserted through the VSD into the LV cavity. An
appropriate size-matched device is then chosen. Whilst on a beating heart,
the left disc of the device is deployed in the LV cavity and pulled back to the
septum. The right ventricular disc is deployed in the RV and opposed to the
septum, closing the VSD; C) echocardiography is used to assess the
ventricular septum for adequate positioning (red asterisk) and absence of
any residual flow. IVS = interventricular septum; RA = right atrium; RV = right
ventricle; PA = pulmonary artery; LA = left atrium; LV = left ventricle.
6 Congenital angiography and catheter interventions
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23 What are the principles of percutaneous pulmonary
valve replacement?
It is reasonable to consider percutaneous pulmonary valve
•
replacement in a patient with severe pulmonary regurgitation or
stenosis provided the patient meets the anatomical criteria for the
available percutaneous pulmonary valves, which include:
a) pulmonary insufficiency >25% and one of the following cardiac
magnetic resonance imaging quantitative criteria:
i) RV end-diastolic volume indexed (RVEDVi) >150mL/m2;
ii) RV end-systolic volume indexed (RVESVi) >80mL/m
iii) RV ejection fraction <47%;
iv) LV ejection fraction <55%;
b) haemodynamically significant abnormalities, defined as RVOT
obstruction with RV systolic pressure ≥70% of systemic
pressure, and at least moderate tricuspid regurgitation;
c) symptoms and signs of heart failure, including exercise
intolerance (defined as exercise testing with ≤70% predicted
peak VO2for age and sex, not explained by chronotropic
incompetence) or syncope attributable to arrhythmia;
d) QRS duration >160ms on electrocardiogram.
2
;
235
Ideally, patients should have a previously implanted conduit ranging
•
between 16 and 29mm, or an RVOT or pulmonary artery with similar
diameters.
Transcatheter valves are also indicated for valve-in-valve placement,
•
for example, in patients with prior surgical biological or transcatheter
pulmonary valve placement.
Prior to pulmonary valve replacement, it is important to assess and
•
treat where necessary any associated anomalies, such as pulmonary
artery stenosis, bifurcation stenosis and residual intracardiac defects.
Pre-procedural cardiac magnetic resonance imaging or CT
•
angiography are useful to define anatomy.
Coronary compression by the implanted valve is a risk, which
•
increases with prior coronary interventions, such as patients who
have undergone an arterial switch or Ross procedure. For this, a
coronary challenge of angiographic assessment of coronary artery
anatomy with simultaneous balloon dilation of the estimated landing
zone of the pulmonary valve can be performed.
24 Which pulmonary valves are available for
transcatheter pulmonary valve replacement?
Edwards SAPIEN XT™ Transcatheter Heart Valve (THV) — which
•
consists of a balloon-expandable, radiopaque, cobalt-chromium frame,
a tri-leaflet bovine pericardial tissue valve and polyethylene terephthalate
Key Questions in CONGENITAL CARDIAC SURGERY
(PET) fabric skirt. The available sizes range between 23mm and 29mm,
requiring a 16-20Fr hydrophilic sheath for insertion.
Edwards SAPIEN™ valves — which are available in multiple
•
generations with the newest available being the SAPIEN 3™ (Figure
22A) and SAPIEN Ultra™ (Figures 22B and C). The SAPIEN 3™ is
made with a radiopaque, cobalt-chromium frame, tri-leaflet bovine
pericardial tissue valve, and polyethylene terephthalate (PET) fabric
skirt. It has a lower profile than the SAPIEN XT version and only
requires a maximum sheath size of 16Fr for the 29mm valve.
Edwards Alterra Adaptive Prestent™ (Figure 22D) — which is a self-
•
expanding stent that allows percutaneous valve replacement in the
native right ventricular outflow. The Alterra Adaptive Prestent™ is
designed to reduce the diameter of large irregular RVOTs and provide
a circular, semi-rigid landing zone to place a SAPIEN 3™ THV.
236
A
C
MPA
Valve
B
D
Figure 22. A) Edwards SAPIEN 3™ valve; B) Edwards SAPIEN Ultra™ valve and
C) angiographical image demonstrating it deployed across the pulmonary
valve; D) Edwards Alterra Adaptive Prestent™. MPA = main pulmonary artery.
Reproduced with permission from Edwards Lifesciences Corporation.
6 Congenital angiography and catheter interventions
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Medtronic Melody™ Transcather Pulmonary Valve (Figure 23) —
•
which is made of a bovine jugular vein (BJV) valve sutured within a
platinum iridium frame. There are three available sizes (18mm, 20mm
and 22mm) and the delivery system constitutes a 22Fr sheath.
AB
MPA
Valve
Figure 23. A) Medtronic Melody™ Transcatheter Pulmonary Valve; and B)
angiographical image demonstrating it deployed across the pulmonary valve.
Reproduced with permission from Medtronic.
Other transcatheter pulmonary valves are undergoing trials for
•
approval in Europe and the United States.
25 What are the indications for intervention on coarctation
of the aorta?
Whilst angioplasty alone does have a place in the management,
•
modern practice has evolved to a predominantly primary stent
angioplasty strategy in patients weighing more than 20kg.
The recommendations for transcatheter balloon angioplasty include:
•
237
a) recoarctation when associated with a transcatheter systolic
gradient of >20mmHg or in the presence of significant
collateral vessels and suitable angiographic anatomy,
irrespective of patient age;
b) patients with a univentricular heart or significant ventricular
dysfunction may not exhibit high gradients but are candidates
for intervention.
It is reasonable to consider balloon angioplasty of native coarctation
•
(Figure 24) as a palliative measure to stabilise a patient irrespective
of age when extenuating circumstances are present, such as
Key Questions in CONGENITAL CARDIAC SURGERY
AB
238
Figure 24. Lateral view angiographic images demonstrating: A) a tight and
discrete hour-glass coarctation (arrows); and B) improvement (red arrows)
following balloon angioplasty.
severely depressed ventricular function, severe mitral regurgitation,
low cardiac output, end-organ dysfunction (such as renal failure), or
systemic disease affected by the cardiac condition.
The recurrence rate is higher for younger patients (<6 months of
•
age), and there is a small but important incidence of aneurysm
formation after balloon dilation of native coarctation at any age.
The recommendations for transcatheter stent placement (Figure 25)
•
in native coarctation or recoarctation include:
a) recurrent coarctation in patients who are of sufficient size for
safe stent placement, in whom the stent can be expanded to
an adult size, and who have a transcatheter systolic coarctation
gradient >20mmHg.
Where possible, a stent that can be expanded to an adult size should
•
be used. Current limiting factors are the size of the sheath required
to deliver such a stent.
The availability of surgical expertise and stent technology should
•
dictate local institutional practice.
Balloon and/or stent angioplasty of coarctation carries a serious risk
•
of vessel disruption and bleeding. Covered stent technology offers
some protection from this complication and many operators use the
6 Congenital angiography and catheter interventions
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AB
*
Before stent After stent
Figure 25. Lateral view angiographic images demonstrating: A) a tight hour-
glass coarctation with mild pre-stenosis dilatation; and B) improvement
following balloon angioplasty and stent insertion (asterisk).
covered CP Stent™ (Figure 26) by choice, accepting that the
sheaths required to deliver such stents may limit their use to teenage
and adult patients.
239
Figure 26. Covered CP Stent™ used for
coarctation of the aorta.
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