Corresponding Author Information:
Dr. Satinder Sandhu MD
Professor of Pediatrics
Director, Pediatric Cardiac Cath Laboratory
Director, Adult Congenital Heart Disease
1611 NW 12th Avenue, NW Room109
Miami, Florida, 33136
Phone: 305-585-6683
Fax: 305-324-6012
Email: ssandhu3@med.miami.edu
Acknowledgements : The authors have no acknowledgments to
mention.
The Gerbode defect occurs in 0.08% of congenial intracardiac shunts (1)
with a higher incidence reported by Yuan et al (2) when acquired defects
are taken into account. The septal leaflet of the tricuspid valve
attaches to the membranous septum lower than the attachment of the
mitral valve. The Gerbode defect results from a deficiency of the
atrioventricular (AV) membranous interventricular septum resulting in a
left ventricle to right atrial shunt. The Gerbode defect was initially
classified as direct and indirect (3). The direct Gerbode type defect is
a deficiency of the atrioventricular (AV) membranous septum. The
indirect Gerbode defect is associated with a ventricular septal defect
resulting in a perforation of the tricuspid valve from the jet coursing
through the ventricular septal defect resulting in a left ventricle to
right atrial shunt. This classification was subsequently modified
relative to the position of the defect to the tricuspid valve as
supravalvar, infravalvar or intermediate (4,5). Defects with both
supravalvular and infravalvular involvement are referred to as
intermediate defects. The Gerbode defect should be suspected on
transthoracic echocardiogram when there is high doppler velocity from
the left ventricle to the right atrium. This defect is unlikely to close
spontaneously and can result in volume overload of the right side. It
also carries the risk for endocarditis. Successful surgical closure of a
left ventricle to right atrial shunt was first described by Kirby et al
(6) in 1957 in a patient where the anatomical details were identified
intraoperatively. Gerbode et al (7) in 1958 published a case series of 5
patients with a perimembranous ventricular septal defect (pmVSD) that
resulted in a left ventricle to right atrial shunt and identified the
defect as the “Gerbode defect”. Due to the proximity of the defect to
the coronary sinus, conduction system and tricuspid and aortic valves
there are anatomical challenges related to transcatheter device closure.
In 2006 Trehan et al (8) reported the first transcatheter closure of an
acquired Gerbode defect. There are few published case reports and small
series reports of immediate and short term results following
transcatheter closure of the Gerbode defect.
Haddad et al (9) in a retrospective multicenter study contribute their
experience on percutaneous closure of the indirect Gerbode type pmVSD.
Transcatheter closure was performed on 10 patients from 3 centers from
Aug 2017-May 2021. The patients ranged in age from 2.5-54 years (median
age 6.8 years) and in weight from 12-88 Kg (median weight 26.5 Kg).
Median left ventricular defect size was 10 mm, (range, 3-15.5 mm).
Transthoracic echocardiogram was used to assess the size of defect,
presence or absence of the subaortic rim, aortic regurgitation, aortic
cusp prolapse, and tricuspid regurgitation. Length deficiency, absence
of subaortic rim and tear drop type of aortic valve prolapse with
trivial aortic regurgitation was not a contraindication to the device
placement. Transcatheter closure of the defect was done under
fluoroscopic and TEE guidance and the selection of the device was center
and operator based. The devices placed were Amplatzer duct occluder
(ADO) II, KONAR-Multifunctional Occluder and ADO I. This is the first
report of device closure of the Gerbode defect with the
KONAR-Multifunctional occlude. Device placement was retrograde in 9/10
and transvenously through an arteriovenous loop in the single patient
with the ADO I device. The diameter of the device placed did not exceed
the diameter of the defect on the left ventricular aspect of the septum
except in patients with deficiency of the subaortic rim where a device
1-2 mm larger than the defect diameter was placed. At a follow up
interval of 3-48 months (median 17 mos) no patient had heart block or
tricuspid valve stenosis. There was complete resolution of the shunt and
all patients had significant improvement of their tricuspid
regurgitation. There was no change in pre-existing aortic regurgitation
with one patient developing new onset aortic regurgitation that remained
trivial on follow up at 4 years post closure. There were 6 patients with
an absent subaortic rim and device placement did not cause aortic
regurgitation or interfere with aortic valve function. The authors then
go on to comprehensively detail the risks and considerations of closing
Gerbode-type defects, listing current literature available while aptly
pointing out the lack of homogenized guidelines available when
considering this type of pmVSD for transcatheter closure. Haddad et al
(9) have effectively demonstrated that percutaneous closure of Gerbode
type pmVSD’s is a safe and effective alternative to surgical repair and
is a valuable addition to the currently available literature available
on this type of procedure
Advances in echocardiography have allowed for accurate diagnosis and
intra-procedure feedback with regards to optimal device size and device
placement to prevent interference with the valves or the conduction
system. Vijayalakshmi et al (10) in a series of 12 patients describe
successful closure of their pmVSD with one patient developing transient
complete heart block that resolved within 48 hours after administration
of steroids. The current body of literature does not outline the
anatomical characteristics of the defect which would not be amenable to
device closure. A wide range of devices have been used for transcatheter
closure and the choice of device impacts the procedural approach. The
immediate and short-term results of transcatheter closure of the Gerbode
defect are reassuring. However, long term follow up is needed.