Download Non-surgical Alternatives to Repair Congenital Heart Defects

Reference Section
Non-surgical Alternatives to Repair Congenital Hear t Defects
a report by
B a r r y L ove , M D
Director, Congenital Cardiac Catheterization Laboratory, Mount Sinai Medical Center
Children and adults with congenital heart disease are
increasingly benefiting from non-surgical alternatives to
repair their heart defects. The last decade has seen a
remarkable advance in the tools and techniques used to
treat congenital heart disease in the cardiac
catheterization laboratory.This article summarizes a few
of the important tools available in 2005 to treat some of
these conditions.
transesophageal or intracardiac echocardiography. The
center waist completely ‘fills’ the defect itself and the
device is therefore said to be self-centering.This allows
the device to close even large defects—up to 38mm in
diameter.The ASO is available in connecting waist sizes
ranging 4–38mm in diameter. The device can be
retrieved and repositioned before release and is
therefore very user-friendly. Closure rates are excellent
(>98%) and the risk of complications is low.1
Atrial Septal Defect
Secundum atrial septal defects (ASDs) are one of the
most common congenital heart defects. The ASD is a
hole in the atrial septum that allows a portion of blood
returning to the left atrium to pass to the right atrium,
right ventricle and pulmonary arteries, thereby placing
additional work on these heart structures as well as the
lungs. Left untreated, atrial septal defects may lead to
right heart failure, atrial arrhythmias, ventricular
dysfunction, and pulmonary hypertension.
Elective transcatheter closure of ASDs is currently
indicated for patients with ASDs of the secundum type,
with a weight of >15kg and evidence of right ventricular
dilation. As a lot of ASDs are not diagnosed until
adulthood, many are closed in the adult population.
Poised on the cusp of FDA approval is the Helex Septal
Occluder.The device design is a frame made of a single
nitinol wire covered by an expanded polytetrafluorethylene (Gore-Tex®) membrane. In the heart, the
device is formed into two round disks that sit on either
side of the atrial septum. Because the device is not selfcentering, the device disks must be significantly larger
(the manufacturer recommends at least 1.6x) than the
diameter of the defect to ensure that the entire defect is
covered. The devices are available in disks ranging in
size between 15mm and 35mm (in 5mm increments)
and are delivered through a 9 French sheath. One
advantage of this device is its low-profile; disadvantages
include the complexity of the delivery system, and
inability to close defects larger than 22mm.
Barry Love, MD, is Director of the
Congenital Cardiac Catheterization
Laboratory at Mount Sinai Medical
Center in New York. He holds
academic appointments as an
assistant professor in the
Department of Pediatrics and the
Department of Medicine. His clinical
focus is on transcatheter therapies
for all forms of congenital heart
disease in patients from infancy
through adulthood. He is currently
working on using transcatheter
techniques developed for congenital
heart disease in applications related
to acquired heart disease in adults.
Patent Foramen Ovale
Despite many attempts beginning in the 1970s to
invent the ideal transcatheter ASD occluder, the first
and only device to date to receive US Food and Drug
Administration (FDA) approval for ASD closure is the
Amplatzer Septal Occluder (ASO).This device was first
approved in the US in 2002.The device is composed of
a self-expanding nitinol wire frame composed of two
disks and a connecting waist (see Figure 1). Occlusive
polyester fabric patches are sewn inside the frame. The
device is collapsed into a delivery sheath (7–12 French)
that is introduced transvenously and passed across the
atrial septum where the device is then placed in
position across the defect (see Figure 2).The procedure
is assisted by the use of fluoroscopy and either
While a patent foramen ovale (PFO) is found in ~15% of
the normal adult population, it is found in over 50% of
young adults with cryptogenic stroke.2 The implied
mechanism is paradoxical embolization of clot from the
right to left atrium and from there to the cerebral
circulation. Because of the relatively low risk of recurrent
stroke (1% to 5% per year), transcatheter closure of PFOs
is currently indicated for patients with cryptogenic stroke
and PFO who have had a recurrent stroke on medical
therapy.There are two devices that currently have limited
FDA approval—the Amplatzer PFO Occluder and the
CardioSeal. The limited FDA approval (humanitarian
device exemption (HDE)), while not investigational,
1. Omeish A, Hijazi Z M,“Transcatheter closure of atrial septal defects in children & adults using the Amplatzer Septal Occluder”,
J. Intervent. Cardiol. (2001 Feb);14(1): pp. 37–44.
2. Webster M W, Chancellor A M, Smith H J, Swift D L, Sharpe D N, Bass N M, Glasgow G L,“Patent foramen ovale in young
stroke patients”, Lancet (1988 Jul 2);2(8601): pp. 11–12.
BUSINESS BRIEFING: US CARDIOLOGY 2006
1
Reference Section
Figure 1: Demonstration of Amplatzer Septal Occluder
vasoactive substances to the cerebral circulation. Recent
uncontrolled studies have shown a dramatic reduction
in migraine frequency in those patients with PFO who
have undergone transcatheter PFO closure.3 Several
randomized controlled trials with a variety of
transcatheter PFO occluders will start in the US by the
end of the year.
Patent Ductus Arteriosus
The ductus arteriosus is a fetal blood vessel connecting
the aorta with the pulmonary artery. Normally, this
vessel closes in the first days of life; however, if it remains
open, this may lead to pulmonary over-circulation, left
atrial and ventricular dilation, and pulmonary
hypertension. Even in the absence of a significant
hemodynamic burden, a patent ductus arteriosus (PDA)
is a nidus for endarteritis with a risk of ~1% per year.
Indications for PDA closure are therefore any audible or
hemodynamically significant PDA.
Figure 2: Intracardiac Echocardiogram Images of ASD Closure
RA: right atrium LA: left atrium. N.B.: with ICE, the RA is closest to the probe. A: 15mm ASD B: Color flow mapping showing left
to-right flow C: Closure of ASD with 18mm ASO.
requires institutional review board oversight and does not
permit ‘off-label’ usage. Randomized trials comparing
medical therapy with device closure after a first
cryptogenic stroke are under way.
PFO closure is also being investigated as a therapy for
migraine headaches. Studies have shown a strong
association between migraine headache and PFO. The
proposed mechanism is paradoxical shunting of
2
A variety of devices have been used ‘off-label’ to close
PDAs. Small PDAs (≤2mm) are easily closed with
stainless-steel Gianturco coils. Larger PDAs are better
closed with the Amplatzer Duct Occluder, which is a
mushroom-shaped device with a nitinol frame and filled
with an occlusive polyester fabric mesh. This device is
delivered from the venous approach placing the ‘hat’ in
the aortic ampulla and the ‘stem’ in the PDA itself (see
Figures 3 and 4). Closure rates are virtually 100% for
PDAs up to 10mm and complications are rare.4 Patients
who are more than six months old or 6kg in weight are
the best candidates for transcatheter PDA closure.
Due to the small delivery system (5–7 French), excellent
occlusion characteristics, and low-profile, the Amplatzer
PDA Occluder has also been used ‘off-label’ to occlude
other congenital and acquired defects. Examples include
closure of prosthetic paravalvular leaks, and residual
patch-margin ventricular septal defects.5
Ve n t r i c u l a r S e p t a l D e f e c t
The most common ventricular septal defects (VSDs)
are of the membranous type—located just underneath
the aortic valve. There are currently no FDA-approved
devices to close membranous VSDs. There is one
membranous VSD occluder that is available elsewhere
in the world. This device is eccentric with a recessed
aortic margin to avoid interference with this valve.This
3. Reisman M, Chistofferson R D, Jesurum J, Olsen J V, Spencer M P, Krabill K A, Diehl L, Aurora S, Gray W A, “Migraine
headache relief after transcatheter closure of patent foramen ovale”, J. Am. Coll. Cardiol. (2005 Feb 15);45(4): pp. 493–495.
4. Pass R H, Hijazi Z, Hsu D T, Lewis V, Hellenbrand W F,“Multicenter USA Amplatzer patent ductus arteriosus occlusion device
trial: initial and one-year results”, J. Am. Coll. Cardiol. (2004 Aug 4);44(3): pp. 513–519.
5. Love B A, Srivastava S, Nguyen K,‘“Off-label’ Occlusion of cardiac and vascular structures using the Amplatzer Duct Occluder and
Amplatzer Septal Occluder”, Fourth World Congress of Pediatric Cardiology and Cardiac Surgery, Buenos Aires, Argentina 2005.
BUSINESS BRIEFING: US CARDIOLOGY 2006
Non-Surgical Alternatives to Repair Congenital Hear t Defects
device is much more technically demanding to implant
than the ASD or PDA devices. Reports of late complete
heart block are worrisome and thought to be due to the
constant radial force of the nitinol against the bundle of
His, which is intimately associated with the posterior
margin of the membranous VSD. Because the surgical
results for membranous VSDs are generally excellent,
any transcatheter device will need to meet or exceed
this high standard to become an acceptable alternative.
Muscular VSDs are found elsewhere in the ventricular
septum. While situated away from the conduction
system, they are often multiple or associated with a
membranous VSD. Unlike membranous VSDs, muscular
VSDs, especially when multiple or located at the apex
of the heart, are surgically challenging. The only
transcatheter device that is FDA-approved to close these
defects is the CardioSeal. This device is a doubleumbrella device with four ‘arms’ of nitinol wire on each
umbrella supporting a square Dacron patch. Although
this device was originally designed to close atrial
communications, the lack of surgical or transcatheter
alternatives to address complex muscular VSDs allowed
FDA approval of the CardioSeal device for muscular
VSD closure. However, the large delivery system (11
French) and poor retrievability characteristics limit the
utility of the CardioSeal device for this indication.
There is a muscular VSD occluder based on the same
nitinol frame design as their ASD device, but with a
thicker connecting waist and smaller retention disks to
conform to the muscular septum. This device is much
easier to retrieve and reposition, and has a smaller
delivery system than the CardioSeal. It is in the final
phases of FDA approval.
Figure 3: Amplatzer Duct Occluder
Figure 4: 12-month-old with 3.5mm Patent Ductus
Arteriosus
Ao: Aorta. MPA: Main pulmonary artery. A: Aortogram showing PDA. B: Aortogram postclosure of PDA with 6/8 Amplatzer Duct Occluder (ADO).
Figure 5: Seven-month-old Status-post Repair of
Truncus Arteriosus with Severe Right Ventricle to
Pulmonary Artery Homograft Stenosis
A VSD occluder specifically designed to treat postmyocardial infarction (MI) ventricular septal defects is,
at present, limited to investigational use in the US.
Stenotic and Regurgitant Lesions
A mainstay of interventional congenital cardiology is
the use of transcatheter balloon dilation and stenting to
relieve vascular stenoses. Areas that frequently require
dilation and/or stenting in the congenital population
are the pulmonary arteries, aorta, and various conduits
and venous baffles. Most of the balloons and stents used
by congenital cardiologists were designed and approved
for use in the peripheral vascular and biliary systems. In
the past few years, several balloons have been
specifically manufactured for congenital cardiology
applications. One example is the ‘Balloon-in-Balloon’
(BiB), which is an innovative design with a smaller
inner balloon and larger outer balloon. This design
facilitates the delivery of large stents in structures, such
as the pulmonary artery or aorta, limiting the risk of
balloon rupture during stent placement.
BUSINESS BRIEFING: US CARDIOLOGY 2006
RV: right ventricle. A: Right ventriculogram showing severe conduit stenosis. B & C:
Placement of premounted Genesis transhepatic biliary stent 10mm x 29mm (Cordis
Endovascular,Warren, NJ) across homograft stenosis. D: Right ventriculogram poststenting showing relief of obstruction.
3
Reference Section
The stents used by congenital cardiologists in the US
are all adapted from other approved indications such as
biliary and peripheral vascular stenting. Though
designed for other applications, the availability of
premounted stent-balloon combinations has greatly
facilitated the delivery of medium-sized stents in small
children (see Figure 5).
desirable to avoid repeat surgery. The current
technology is based on a bovine interval jugular valve
mounted inside a balloon-expandable stent. Early
work conducted in Europe developing this system
appears promising.6 The long-term durability of these
implanted valves remains to be seen.
Summary
Early clinical trials are under way to evaluate the use
of transcatheter delivery of stent-mounted valves.
Many congenital heart patients have had
reconstruction of the pathway from the right ventricle
to the pulmonary artery with surgically placed, valved
homografts. As the valve function of these homografts
deteriorates over time, these patients can be left with
significant pulmonary regurgitation—the deleterious
consequences of which are increasingly being
appreciated.Transcatheter placement of a new valve is
Many tools to treat children and adults with congenital
heart disease are devices adapted from other
applications. Recently, devices specifically for use in
congenital heart disease have been FDA-approved and
have dramatically advanced the non-surgical care of
patients with congenital heart disease. Further
development of tools specifically designed for
congenital heart applications are forthcoming and will
continue to advance the field. ■
6. Khambadkone S, Coats L, Taylor A, Boudjemline Y, Derrick G, Tsang V, Cooper J, Muthurangu V, Hegde S R, Razavi R S,
Pellerin D, Deanfield J, Bonhoeffer P,“Percutaneous pulmonary valve implantation in humans: results in 59 consecutive patients”,
Circulation (2005 Aug 23);112(8): pp. 1,189–1,197.
4
BUSINESS BRIEFING: US CARDIOLOGY 2006