double outlet right ventricle (dorv) is a
partial abnormality of ventriculoarterial
connection and intracardiac ventricular
septation. It is a congenital anomaly in
which both great arteries arise wholly or
in large part from the right ventricle.
Both the arrangement of the
atrioventricular valves and the
ventriculoarterial connections are quite
variable, and lie somewhere in between
those noted in the tetralogy of fallot and
those in d-transposition. The aorta and
main pulmonary artery are dextrorotated
from the normal arrangement, and are
classically side-by-side or nearly so.
There is often both a subaortic and a
subpulmonary infundibulum, in contrast to
classic tetralogy of fallot in which there
is only a subpulmonary conus, or to
d-transposition in which there is only a
subaortic conus. The great vessel
relationships also lie somewhere in
between that of the tetralogy of fallot
and of d-transposition, resulting in both
aorto-mitral and aorto-tricuspid
discontinuity.
The actual diagnosis of dorv takes into
account the morphology of only a very
small part of the heart, namely that of
the ventriculoarterial junction. There
are numerous additional abnormalities of
atrial arrangement and atrioventricular
connections, any of which can be
associated with the abnormal
ventriculoarterial connection. When
present, these anomalies, such as atrial
isomerism or discordant or double-inlet
atrioventricular connections, dominate the
clinical picture and are referred to in
other sections. Only the largest subset
of double outlet ventricle are considered
in this section, those with the usual
atrial arrangement and concordant
atrioventricular connections. Within this
subsets, there are many anatomical
variants, the most important variable
feature being the location of the
ventricular septal defect. The location
of the ventricular septal defect forms the
basis for both a morphological and
operative classification, although within
this spectrum of variability, any position
of the aorta can combine with any position
of the main pulmonary artery and any
location of the ventricular septal defect
thereby creating an infinite number of
morphological possibilities. Only rarely
is dorv found in the presence of an intact
ventricular septum, and in almost all such
circumstances the features would suggest
that intrauterine or postnatal closure of
a preexisting ventricular septal defect
took place.
Dorv.Gif (32931 bytes)
the ventricular septal defect was
classified by lev as being subaortic,
subpulmonary, doubly-committed, and
noncommitted.
(a) subaortic ventricular septal defect.
Double outlet right ventricle with
subaortic ventricular septal defect is the
most common sub-type, and is
morphologically a close cousin to
tetralogy of fallot. The ventricular
septal defect, which is the primary outlet
from the left ventricle, is located
beneath the outflow tract supporting the
aortic valve, and as in the tetralogy of
fallot, is positioned between the limbs of
the septomarginal trabeculation. In this
setting, the leaflets of the aortic valve
often override the crest of the
ventricular septum, and there can be doubt
about which ventricle the aorta is most
connected to, particularly when the
morphology of tetralogy of fallot is also
present. Then, although there is
discontinuity between the aortic valve and
both atrioventricular valves, there still
remains fibrous continuity between the
mitral and tricuspid valves - that is, for
the ventricular septal defect to be
perimembranous. This feature is of
surgical importance, since it indicates
that the conduction tissue is closely
related to the margin of the
interventricular communication at its
postero-inferior rim. Only rarely with a
subaortic interventricular communication
is there discontinuity between the mitral
and tricuspid valves.
Irrespective of the infundibular
morphology, the interventricular
communication is the only direct outlet of
the left ventricle. Therefore, stenosis
of the interventricular communication
effectively produces subaortic obstruction
although there is, of course, free access
to the aortic outflow tract from the right
ventricle. In the majority of cases
however, the subaortic outflow tract is
widely patent from both ventricles, and
the outlet septum, which in this setting
is an exclusively right ventricular
structure, is deviated in antero-cephalad
direction to produce subpulmonary
obstruction. Almost always the arterial
trunks are normally related when the
interventricular communication is
subaortic, or side-by-side with the aorta
to the right. In one rare variant,
however, the aorta can be anterior and to
the left of the pulmonary trunk (with
usual atrial arrangement and concordant
atrioventricular connections). Although
the ventricular septal defect is almost
always in subaortic position with this
rare pattern, making it possible in most
cases for the surgeon to connect the aorta
directly to the left ventricle, the septal
defect can rarely occupy the locations to
be described below when the aorta is
left-sided.
(b) subpulmonary ventricular septal
defect. With this arrangement, the
ventricular septal defect is between the
limbs of the septomarginal trabeculation,
but in a subpulmonary (rather than a
subaortic) location. This pattern, the
second most frequent, is associated with
parallel alignment of the arterial trunks,
the aorta being to the right and slightly
or markedly anterior to the pulmonary
trunk. It is the orientation of the
outlet septum, an exclusively right
ventricular structure, that is the central
feature, and the resulting lesion is
usually described as the taussig-bing
heart. Such hearts exhibit a spectrum of
malformation determined by the precise
connection of the overriding pulmonary
valve. In most cases, there is mitral to
tricuspid discontinuity, so that the
defect has a muscular postero-inferior
rim. Rightward deviation of the outlet
septum producing subaortic obstruction is
also frequent, as is aortic coarctation.
Straddling and overriding of the mitral
valve is the other malformation frequently
associated with this pattern of dorv.
(c) doubly-committed, juxta-arterial
ventricular septal defect. This subgroup
of double outlet right ventricle is also
closely related to tetralogy of fallot.
The central feature of this subgroup is
complete absence of the muscular outlet
septum, so that there is fibrous
continuity between the facing leaflets of
the aortic and pulmonary valves. The
large interventricular communication is
located immediately beneath both the
aortic and valves, which have a marked
tendency to override. The defect can be
associated with mitral - tricuspid
continuity and therefore be
perimembranous, or with mitral - tricuspid
discontinuity, and have a muscular
postero-inferior rim. Reminiscent of the
tetralogy of fallot, the raphe between the
arterial valves is deviated in an
antero-cephalad direction to produce
pulmonary stenosis with overriding of the
aortic valve. Hence, this variant can be
diagnosed as tetralogy of fallot, although
it is best considered as dorv with a
doubly-committed and juxta-arterial
ventricular septal defect, and describe
the mode of ventriculoarterial
connection.
(d) noncommitted ventricular septal
defect. This is the most complex variant
of double outlet right ventricle. Most
commonly, the defect is noncommitted
because it is perimembranous and opens
into the right ventricle beneath the
septal leaflet of the tricuspid valve, or
because the tension apparatus of the
atrioventricular valves is interposed
between the margins of the defect and the
subarterial outflow tracts. The surgical
correction of these variants is quite
difficult, and complete repair may not be
possible. Rarely is the defect
noncommitted because it is within the
inlet or apical trabecular components of
the muscular septum. To this extent,
there is a conflict between the anatomical
and functional definitions of a
noncommitted defect. What is anatomically
a committed defect may be rendered
noncommitted functionally because of the
interposition of vital structures, usually
a valvar tension apparatus, between the
defect and the arterial valves. These
features are of profound surgical
important, and must be taken into account
in order to decide when a defect is
noncommitted or subarterial.
Hemodynamics
the hemodynamics are dependent on the
position of the ventricular septal defect,
the relationships of the great arteries,
and the presence of associated cardiac
malformations, such as outflow obstruction
and atrioventricular valve abnormalities.
Variable degrees of cyanosis are present
in all patients, depending on the location
of the ventricular septal defect and the
volume of pulmonary blood flow. Patients
with dorv and unrestricted pulmonary blood
flow have hemodynamics indistinguishable
from those with an nonrestrictive
ventricular septal defect; those with
pulmonary stenosis have hemodynamics
analogous to tetralogy of fallot; and
those with subaortic stenosis
(taussig-bing heart) have hemodynamics
similar to transposition of the great
arteries with a large ventricular septal
defect.
Clinical findings
the clinical findings are also quite
variable, although most patients present
in early infancy. Patients with double
outlet right ventricle and pulmonary
stenosis present analogously to those with
tetralogy of fallot, cyanosis may be
initially mild but may progress, and young
infants may exhibit cyanotic spells.
Patients with a large nonrestrictive
ventricular septal defect and no outflow
tract obstruction usually present at
around 3 months of age with congestive
heart failure and minimal signs of
cyanosis, and finally those with double
outlet right ventricle, unrestricted
pulmonary blood flow and left ventricular
outflow tract obstruction may present with
severe congestive signs and poor
peripheral perfusion.
Echocardiography localizes the position of
the ventricular septal defect,
demonstrates the relationships of the
outflow tracts and the presence of
obstruction(s) if present, and defines any
atrioventricular valve abnormalities.
Importantly, echocardiography is able to
assess the tricuspid-pulmonic valve
distance, and define the presence of
straddling atrioventricular valves.
Cardiac catheterization is performed to
further define the anatomy, to obtain data
on pulmonary vascular resistance and to
identify coexistent conditions.
Medical & surgical management
palliative operative procedures include
pulmonary artery banding in cases of
excessive pulmonary blood flow, and
placement of systemic-pulmonary shunts in
cases of pulmonary outflow tract stenosis.
Palliative procedures are currently
utilized only in cases in which definitive
correction is anatomically not feasible.
The goal of corrective operative
management is to achieve a biventricular
repair, in which the left ventricle is
connected to the aorta, and the right
ventricle to the main pulmonary artery.
There are three main variables to be
considered when deciding upon the most
suitable operation, these being the
location of the ventricular septal defect,
the degree of tricuspid - pulmonary
discontinuity, and the presence of right
or left ventricular outflow tract
obstruction. Often time, the decision on
which operation to perform depends on the
intraoperative findings.
Repair with subaortic or doubly-committed
ventricular septal defect.
In the spectrum of double outlet right
ventricle that is tetralogy of
fallot-like, namely in the presence of a
subaortic or doubly-committed,
juxta-arterial ventricular septal defect,
and adequate tricuspid - pulmonary
discontinuity to allow for an unobstructed
intraventricular baffle, (usually at least
equal to the diameter of the aortic
annulus), a kawashima intraventricular
repair can generally be performed, in
which the ventricular septal defect is
baffled directly to the aorta by use of a
tunnel.[306, 310] when the morphology is
not favorable for an intraventricular
repair, due either to insufficient
tricuspid - pulmonary discontinuity or to
pulmonary stenosis, then the pulmonary
valve may be sacrificed in order to gain
sufficient space to place an
intraventricular baffle. Right
ventricular to pulmonary artery continuity
is then established by a conduit, the
so-called rastelli operation. Three other
operations, not in common use include
réparation à l’étage ventriculaire
(rev operation)[61], nikaidoh’s aortic
translocation operation[54], and the
pulmonary translocation operation. These
operations are described in greater detail
below. Resection of the outlet septum or
enlargement of the ventricular septal
defect may also be necessary to avoid
outflow obstruction.
Repair with subpulmonary ventricular
septal defect.
In the spectrum of double outlet right
ventricle that is d-transposition-like,
namely that there is a subpulmonary
ventricular septal defect and insufficient
tricuspid - pulmonary discontinuity, two
options are available for complete repair
without the use of a conduit. These
include the arterial switch operation, in
which an intraventricular patch diverts
blood from the ventricular septal defect
to the pulmonary valve and a standard
arterial switch operation is
performed[53], and the pulmonary
translocation operation, (see below). A
third option is the damus-kaye-stansel
operation, in which an intraventricular
patch diverts blood from the ventricular
septal defect to the pulmonary valve, the
main pulmonary artery is divided at its
bifurcation, the proximal end is
anastomosed to the ascending aorta, and
the right ventricular outflow tract
reconstructed with a valved conduit from
the right ventricle to the distal divided
end of the main pulmonary artery.
Resection of the outlet septum or
enlargement of the ventricular septal
defect may also be necessary to avoid
outflow obstruction.
Repair with noncommitted ventricular
septal defect.
The most common form of noncommitted
ventricular septal defect is the
atrioventricular septal defect, which
extends under the septal leaflet of the
tricuspid valve. Several authors have
suggested that when this defect occurs
with pulmonary stenosis, (which thereby
precludes an arterial switch operation),
the procedure of choice is patch closure
of the ventricular septal defect with
creation of a generous anterior and
superior extension. The ventricular
septal defect extension is then baffled to
the aorta as for the standard
intraventricular repair described
previously. However, in view of the known
tendency for surgically created
ventricular septal defects to close
spontaneously, as well as the inherent
risk of creating subaortic stenosis with
the tunnel repair, this approach is
generally best avoided.
Certain anatomic forms of double outlet
right ventricle require surgical
approaches that are more closely related
to those used for management of a
functional single ventricle[538]. In
these forms of double outlet right
ventricle, the right ventricle is quite
hypoplastic, and the defect results in
essentially a single functional ventricle.
In this subgroup, there is frequently a
straddling tricuspid valve and sometimes a
superior-inferior ventricular
relationship. In other forms of double
outlet right ventricle the left ventricle
is hypoplastic, and frequently there is
hypoplasia or atresia of the mitral valve.
However, in still other patients there
are two relatively well-formed ventricles,
but the ventricular septal defect is of
the atrioventricular septal defect type,
and construction of a baffle to divert the
left ventricular output to the aorta may
be extremely difficult without disruption
of the tricuspid chordal attachments and
anterior enlargement of the ventricular
septal defect. Under all of these
circumstances, a univentricular palliation
may be elected. When a univentricular
palliation is considered, the critical
surgical features are the function of the
atrioventricular valves and obstruction to
outflow from both ventricles into the
aorta. There is a high incidence of
obstruction to either the aorta or the
pulmonary artery in patients with double
outlet right ventricle, in addition,
straddling tricuspid valves and common
atrioventricular valves are not
infrequently regurgitant in patients with
double outlet right ventricle.
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needy07
New User, Becoming EHEALTHy
Joined: 07 Feb 2007 Posts: 4
More Dorv Posted: 02-10-07 21:48pm
That is very interesting about dorv. So
what are the stats on that. Like how
common is it? What causes it? After
repairing what are the chances of recovery
if any? After surgery are there any
other problems that can occur?
