CAVC and Tetralogy of Fallot: Surgical Considerations. F.J.Vargas et al.

Complete Atrioventricular Canal
and Tetralogy of Fallot: Surgical Considerations
Florentino J. Vargas, M.D.,* Eduardo Otero Coto, M.D., John E. Mayer, Jr., M.D.,
Richard A. Jonas, M.D., and Aldo R. Castaneda, M.D.
ABSTRACT A review of 13 autopsy specimens and of 13
patients who were operated on for complete atrioventricular (AV) canal and tetralogy of Fallot between 1975 and
1985 revealed a number of anatomical details that are important in the successful repair of this combined lesion. A
bridging anterior leaflet was present in 25 hearts. A septum
primum was present and attached to leaflet tissue in 13. In
all 26, a ventricular septal communication was present beneath the bridging anterior leaflet and extended anteriorly,
but in 14 there was no ventricular septal defect underneath
the posterior leaflet. Additional pathological features included the following: leaflet tissue deficiency (4 hearts),
single left papillary muscle (3), accessory valve orifice (4),
and left ventricular (4) or right ventricular (RV) (1)dominance. All 26 had infundibular stenosis, and 10 had hypoplastic pulmonary annuli. One had pulmonary atresia, and
6 had branch pulmonary artery stenosis. Surgical technique was modified to include incision of the septum
primum in 7. Because of rightward displacement of the
anterior ventricular septum and also to minimize the risk
of causing subaortic stenosis, the bridging anterior leaflet
was divided more toward the tricuspid orifice so as to parallel the crest of the ventricular septum. Transannular RV
outflow patches were used in 10 patients, and a right ventricle-pulmonary artery conduit was placed in 1 patient.
Three required repair of branch pulmonary artery stenosis.
There were no hospital deaths. Three patients died late of
residual AV valve regurgitation and branch pulmonary artery stenosis (2) and sepsis (1). One patient with RV hypoplasia and postoperative tricuspid regurgitation had a
Fontan operation. Four patients required left AV valve
replacement (3 early and 1 late). The AV canal component
in complete AV canal with tetralogy of Fallot is more complex than in isolated complete AV canal. Also, in addition
to infundibular stenosis, other right-sided obstructions are
common. A better understanding of the many anatomical
variables has led to improvement in surgical results.
From the Department of Cardiovascular Surgery, The Children’s Hospital, and the Department of Surgery, Harvard Medical School, Boston,
MA.
‘Currently Evarts A. Graham Memorial Travelling Fellow (American Association for Thoracic and Cardiovascular Surgery).
Presented at the Twenty-second Annual Meeting of The Society of Thoracic Surgeons, Washington, DC, Jan 27-29, 1986.
Address reprint requests to Dr.Castaneda, Department of Cardiovascular Surgery, The Children’s Hospital, 300 Longwood Ave, Boston,
MA 02115.
258
Ann Thorac Surg 42~258-263,Sep 1986
Although improvement in early and late results has
been reported after repair of common atrioventricular
(AV) canal associated with tetralogy of Fallot [l-61, this
combined lesion remains a serious surgical challenge [3,
4, 6, 71.
The purpose of this report is to review our clinical
experience during the last decade with the surgical repair of complete AV canal and tetralogy of Fallot at Children‘s Hospital, Boston. Pathological specimens of this
dual condition were also analyzed. Features common to
both lesions (complete AV canal [8] and tetralogy [9])
were sought, including type of obstruction of the right
ventricular outflow tract (RVOT), abnormalities of the
common AV valve such as leaflet deficiencies, abnormalities in the number and location of papillary muscles
and chordal attachments, and also the presence of complete AV canal plus ventricular malalignment or ventricular dominance. In addition, we were interested in
evaluating the potential risk of causing subaortic stenosis after closure of the large, malaligned type of ventricular septal defect (VSD) associated with complete AV
canal plus tetralogy of Fallot, and in assessing the function of the reconstructed right AV valve in the presence
of pulmonary regurgitation after placement of a transannular RVOT patch.
Material and Methods
Clinical Characteristics of Patients
Between January, 1975, and December, 1985,13 patients
with complete AV canal and tetralogy of Fallot underwent surgical repair. Diagnosis was predicated on the
presence of complete AV canal including an inlet type of
VSD with anterior (subaortic) extension and associated
subpulmonary stenosis, both caused by anterior
malalignment of the conal septum [4, 10, 111. Patients
with complete AV canal associated with an anatomy of
the conal septum other than tetralogy were excluded.
The right ventricular (RV) pressure was systemic in all
patients. There were 7 boys and 6 girls ranging from 16
months to 16 years old (mean: 7 years). Seven patients
were less than 4 years of age. Down‘s syndrome was
present in 9 patients (69.23%).Four patients had a previous systemic-pulmonary artery shunt. In none of them,
including a child with a two-year history of massive leftto-right shunting, did the resulting left ventricular volume overload seem to accentuate the degree of left ventricular dysfunction, despite the presence of moderate
left AV valve regurgitation in all 4. All 13 patients were
cyanotic during the first year of life. The preoperative
diagnosis was confirmed in all patients by cardiac catheterization and cineangiography. In the last 7 patients,
259 Vargas, Otero Coto, Mayer, et al: Complete AV Canal and Tetralogy of Fallot
echocardiographic studies also correctly diagnosed the
lesion. Preoperatively, AV valve regurgitation was
classified as severe in 3 patients (23.07%) and mild to
moderate in 4 patients (30.77%). End-diastolic RV and
left ventricular pressures were within normal limits.
Anatomical Findings
A number of surgically important features were observed in the 13 patients and in the 13 autopsy specimens (Table).
OSTIUM PRIMUM. The ostium primum component of
the AV canal defect was either small or absent in 13
hearts (50%). In these hearts, the septum primum was
attached by fibrous remnants to either the anterior or the
posterior common leaflet (Figs lA, 2A).
VSD. In 14 hearts (54%), the inlet VSD did not extend
underneath the posterior leaflet (mild deficiency of the
inlet septum). This absence of ventricular septal communication beneath the posterior leaflet was associated
with a small or absent ostium primum in 13 hearts (50%)
(see Fig 1A). Anterior (subaortic) extension of the VSD
caused by malalignment of the infundibular septum was
present in all hearts (see Fig 1).
AV VALVE. A bridging, unattached anterior leaflet was
present in 25 hearts (96%) (see Fig 1A). The posterior
leaflet was undivided and attached by short, thickened
chordae to the crest of the muscular septum in 14 hearts
(54%).In the remainder, severe additional abnormalities
were found in both the common AV valve leaflets and
their chordal attachments (see Table).
VENTRICULAR ANATOMY. Left ventricular dominance
with severe RV hypoplasia occurred in 1 patient. In 3
other hearts, the complete AV canal was predominantly
related to the left ventricle (complete AV canal and ventricular malalignment) (see Table).
RVOT. Subpulmonary stenosis caused by anterior
malalignment of the conal septum was present in all
hearts (see Fig 1A). Additional pulmonary valvular, annular, or arterial obstructions are outlined in the Table.
Because of rightward and anterior deviation of the
ventricular septum, a potential risk for causing subaortic
narrowing after closing the VSD and reattaching the leftsided component of the anterior bridging leaflet was recognized (see Fig 2D). This hazard increases proportionally to the degree of aortic dextroposition.
Operative Management
All 13 patients underwent repair on cardiopulmonary
bypass with moderate hypothermia (28°C). Crystalloid
cold cardioplegia was added in the last 9 patients.
Anatomical Findings from 13 Surgical Patients and 13 Specimens
Anatomical Findings
Operation
Autopsy
Specimen
Total
%
{S,D,DI
Small ostium primum
VSD extended into subaortic position
Absent (or small) VSD underneath posterior leaflet
Common AV valve
Bridging anterior leaflet (type C)
Bridgmg posterior leaflet
Anterior leaflet attached to right of ventricular septum
Severe leaflet tissue deficiency
Single left papillary muscle
Accessory valve orifice
Short thickened chordae
Ventricular dominance
LV dominance
RV dominance
RV outflow tract
Anterior conal malalignment (subpulmonary stenosis)
Pulmonary valve stenosis
Hypoplastic pulmonary annulus
Pulmonary atresia
Branch pulmonary stenosis
Associated anomalies
Persistent left SVC
Right aortic arch
Aberrant right subclavian artery
Anterior descending coronary artery from RCA
13
7
13
10
13
6
13
4
26
13
26
14
100
50
100
54
12
6
1
2
2
1
3
13
8
0
2
1
3
7
25
14
1
4
3
4
10
96
54
4
15
12
15
38
1
1
3
0
4
1
15
4
13
12
8
1
3
13
12
2
0
3
26
24
10
1
6
100
92
38
4
23
4
4
2
1
5
2
1
1
9
6
3
2
35
23
12
8
VSD = ventricular septal defect; AV
artery.
=
atrioventricular; LV = left ventricular; RV
=
right ventricular; SVC = superior vena cava; RCA
=
right coronary
260 The Annals of Thoracic Surgery Vol 42 No 3 September 1986
A
B
w
B
Fig 1. Anatomical findings in complete atrioventricular canal with
tetralogy of Fallot. ( A )Small or absent ostium primum attached to
both anterior and posterior leaflets (1); bridging, unattached anterior
leaflet (2); posterior bridging leaflet attached to the crest of the ventricular septum (no ventricular septal defect [VSDl) (3); V S D with
anterior extension into subaortic area (4);and right ventricular infundibular stenosis (malaligned conal septum) (5). ( B ) Anteriorly deviated (rnalaligned)conal septum. (RA = right atrium; Ao = aorta;
PA = pulmonary artery; RV = right ventricle; P = pulmonary.)
Through an ample right atriotomy, all pertinent structures were first examined. In patients with a small ostium primum, the septum primum was incised and partially resected to expose the complete anatomy of the
common AV valve (see Fig 2A, B). In the initial patients,
the undivided bridging anterior leaflet was incised from
the center of the free edge to the midpoint of the insertion of the leaflet on the annulus of the common AV
valve. In the last 5 patients, we modified this division of
the anterior leaflet to reduce the risk of causing subaortic
stenosis and to reduce tension on the anterior leaflet.
Instead of dividing the superior leaflet into two equal
components, we incised the leaflet obliquely toward the
RV side to parallel the course of the anteriorly deviated
septal crest. This maneuver helped to enlarge the left
ventricular outflow tract, and also minimized the possibility for the left AV valve to protrude into the subaortic
area (see Fig 2D).
In all patients it was possible to close the VSD associated with complete AV canal and tetralogy of Fallot
through the right atrium exclusively. All the VSDs extended anteriorly into the subaortic area, the upper border being limited by the malaligned conal septum. The
aortic valve was visualized through the right atrium, and
the ease of exposure depended somewhat on the degree
of aortic overriding. A single pericardial patch was
sutured to the right side of the septal crest and was then
carried anterior to the coronary sinus. Both left and right
septal leaflet components were then reattached to the
pericardial patch using a continuous horizontal mattress
a\
Fig 2. Surgical anatomical features of complete atrioventricular (AV)
canal with tetralogy of Fallot (TOF). ( A )Small ostium primum. Septum primum is attached by fibrous remnants (arrows) to anterior
and posterior leaflets. ( B ) Incision of septum primum (arrow) to expose the left-sided components of the common A V valve. (C) Repair of
isolated complete A V canal. Midline division of the bridging anterior
leaflet and reattachment to central patch does not narrow left ventricular outflow tract (arrow). (D) Modified technique for repair of complete AV canal with tetralogy of Fallot. Because of the rightward displacement of the conal septum, central division of the anterior leaflet
can produce subaortic narrowing (short arrow) after reattachment of
the anterior leaflet. By dividing the anterior leaflet obliquely following
the crest of the malaligned septum, narrowing of the subaortic area
(long arrow) is avoided. This technique also reduces undue tension
on the left anterior leaflet. (CS = coronary sinus.)
suture. The left anterior and posterior leaflets were also
sutured together (cleft). The remaining pericardial patch
was finally sutured to the ridge of the atrial septum. The
often peculiar configuration of the VSD (either because
of limited extension underneath the posterior leaflet or
because of a very large anterior extension below the anterior leaflet) required individual tailoring of the pericardial patch. In 1 patient it was necessary to partially split
the posteromedial papillary muscle to elongate chordae
of the left AV valve to reduce undue tension and to
avoid incomplete central coaptation of the leaflets.
The techniques used to relieve the various forms of
RVOT obstruction and pulmonary artery stenosis were
as follows: transannular patch in 10 patients with a hypoplastic pulmonary valve annulus; pulmonary artery
patch plasty in 3 patients with branch pulmonary stenosis (all patients also had transannular patches); RV infundibular patch in 2 patients with a hypoplastic infundibulum; and aortic homograft interposition in 1 patient
with pulmonary valve atresia and hypoplastic left and
right pulmonary arteries.
261 Vargas, Otero Coto, Mayer, et al: Complete AV Canal and Tetralogy of Fallot
Results
Comment
Early Results
There were no hospital deaths. All patients were
weaned from cardiopulmonary bypass without difficulty
except 1 who required valve replacement because of
massive left AV valve regurgitation. In this patient a left
anterior papillary muscle inserted onto the right side of
the ventricular septum (Rastelli type B). All patients required inotropic support in the operating room and for
variable lengths of time postoperatively.
Two patients with deficient leaflet tissue (chordal
elongation had been performed in 1)underwent reoperation within thirty days of the first repair, and a prosthetic left AV valve replacement was performed. Valve
tissue deficiency, mostly along the free edge of the leaflets, precluded a renewed attempt at valvoplasty in both.
In 1 patient a double-orifice right AV valve was repaired
with a pericardial patch, but severe right-sided AV valve
regurgitation developed, and the repair was converted
to a modified Fontan operation (with interposition of a
right atrium-RVOT conduit) within twenty-four hours
of the original operation [7]. In this patient, the common
AV valve opened predominantly into the left ventricle
(malaligned common AV valve). In addition to the
double orifice within the right side of the inferior leaflet
(with its own chordal attachments), the right lateral
leaflet was partially muscularized. Another patient required early reoperation for repair of incomplete relief of
left pulmonary artery stenosis after attempts at balloon
dilation of the stenotic area proved unsuccessful. A permanent pacemaker was implanted in 1 patient in whom
permanent complete AV block developed.
The coexistence of complete AV canal and tetralogy of
Fallot is infrequent; it affects 6.8% of patients with complete AV canal [12] and 0.9% of those with tetralogy
[13]. A clearer understanding of anatomical, diagnostic,
and surgical features of this complex lesion has been
achieved in the last 17 years (1-161. Nevertheless, surgical repair still carries a higher risk than repair of isolated
complete AV canal or tetralogy of Fallot [3, 4, 6, 91.
In the past, surgical deaths had been partially ascribed
to inadequate preoperative diagnosis [6, 141. We have
learned that right and left ventriculograms are essential
and that hepatoclavicular views are also of great value in
delineating details of the RVOT anatomy [15]. In a recent
report, Nath and colleagues [16] demonstrated a characteristic cephalocaudal movement of the right side of the
common AV valve in complete AV canal with tetralogy
of Fallot, which differs from the displacement (parallel to
the axis of the tricuspid valve) found in normal hearts.
This distinctive feature is particularly relevant when
there is either an intact septum primum attached to the
common leaflets or when the VSD does not extend
underneath the inferior leaflet. Under these conditions,
conventional angiography can be misleading by suggesting two separate AV valves. In patients with tetralogy of
Fallot, the cephalocaudal motion of the right side of the
common AV valve should arouse suspicion about the
presence of complete AV canal from the right ventriculogram alone, thus indicating the need for a left
ventriculogram.
These advances in angiocardiographic techniques,
together with the impressive diagnostic accuracy of
echocardiography [4, 171 in demonstrating both the
anatomy and function of the common AV valve should
eliminate diagnostic errors as factors of operative death.
Two-dimensional echocardiographic studies are very
helpful in diagnosing tetralogy of Fallot (parasternal
axis) and complete AV canal (apical four-chamber view)
[4, 171. The correct diagnosis was made in all 7 patients
who had echocardiography in this series. Echocardiography has also permitted delineation of ventricular size
and volume [18]. The attempt at repair could have been
avoided and a modified Fontan operation could have
been performed as the initial procedure in 1 of our patients if two-dimensional echocardiographic studies had
been available at that time [7]. Therefore, with the present state of diagnostic accuracy of echocardiography and
angiography, other features must be considered as possible determinants of surgical outcome.
Marked deficiency of leaflet tissue and abnormal chordal attachments represent, in our experience, the other
major cause of morbidity. Although satisfactory reconstruction of the left AV valve was achieved initially in all
but 1 patient (as judged by immediate postoperative left
atrial pressure tracings), early or late replacement of that
valve became necessary in 3 patients who had severe
valve tissue deficiency. Deficiency of leaflet tissue and
undue tension on suture lines favor dehiscence of the
Lute Results
Follow-up ranges from 2 months to 10 years (mean, 4.3
years). There were 3 late deaths. Two occurred in patients with residual right-sided obstructions; l patient
died 4 months after operation of severe bilateral pulmonary artery hypoplasia, and the other died 7 months
postoperatively of residual left pulmonary artery stenosis. Both of these patients also had moderate residual left
AV valve regurgitation. The third patient died of salmonella B sepsis on a left AV valve prosthesis 1 year after
repair.
In 1 patient progressive left AV valve regurgitation
developed and necessitated replacement of that valve 9
months after the original operation. The free border of
the reconstructed septa1 leaflet had become scarred and
retracted.
The 10 survivors are all doing well, and have no clinical or echocardiographic findings suggestive of left or
right AV valve incompetence. Three of the survivors
with transannular RVOT patches underwent recatheterization, and neither hemodynamic nor angiographic evidence of severe AV valve incompetence was found.
End-diastolic RV and left ventricular pressures were
within normal limits.
262 The Annals of Thoracic Surgery Vol 42 No 3 September 1986
reconstructed valve either at the level of the cleft or at
the site of leaflet reattachment to the patch. Also, the
relatively frequent coexistence of anomalies of the left
side of the common AV valve (single papillary muscle,
accessory valve orifices, anomalous chordae tendineae)
must be taken into account during preoperative evaluation and intraoperative repair.
A restrictive pulmonary valve annulus and the consequent need for a transannular patch has been considered
a risk factor in previous reports [2,3]. However, transannular RVOT patches did not affect early mortality in our
experience (10 of our 13 patients had transannular
patches without an operative death). Satisfactory hemodynamic results were noted in the 3 patients with transannular patches who underwent postoperative catheterization despite moderate degrees of pulmonary valve
regurgitation. On the other hand, residual localized or
diffusely restrictive pulmonary artery branches and residual RV hypertension (more than half systemic pressure) clearly increased late mortality and morbidity.
Therefore, careful preoperative assessment of the RVOT
and pulmonary arteries is important particularly in view
of the 65% incidence of severe obstructions between the
right ventricle and pulmonary artery in this group of
patients.
Left ventricular or RV dominance has been recognized
as adversely affecting surgical outcome in isolated complete AV canal [8]. A hypoplastic right ventricle, in addition to right AV valve regurgitation, required transformation of the original repair into an immediate modified
Fontan procedure in 1of the patients [7]. Hepatoclavicular views [15] and other angiographic and echocardiographic techniques should now eliminate the need for
intraoperative improvisations.
The presence of a small ostium primum requires incision and partial resection of the septum primum to gain
sufficient exposure of the common AV valve anatomy.
The electrocardiographic finding of an inferiorly deviated QRS axis in patients with a small or absent VSD
underneath the posterior leaflet has been previously reported [19]. It probably could be related to a different
anatomical course of the conduction tissue in these patients (a superiorly oriented QRS axis has been described
in the classic complete AV canal type of VSD with larger
deficiencies of the inlet septum) [20]. If the position of
the conduction tissue is assumed to be similar to that in
classic complete AV canal, that is, in the posteroinferior
crest of the defect, it can be speculated that the bundle of
His would be distant from the suture line in these patients in whom the VSD is not extended posteriorly.
Although subaortic stenosis did not develop in any
of our patients after repair, this complication has been
reported to be a cause of death [4].The proposed
modification of dividing the superior leaflet parallel to
the edge of the VSD (see Fig 2C, D) (i.e., more rightward
than in simple complete AV canal to adjust for the anterior and rightward deviation of the conal portion of the
ventricular septum) should minimize or even eliminate
this potential complication. Iatrogenic subaortic obstruction is more likely to occur in patients with extreme
aortic dextroposition.
The last decade has produced more encouraging results with the repair of complete AV canal plus tetralogy
of Fallot. These advances are due mostly to improved
preoperative diagnostic accuracy and to a clearer understanding of the anatomical variables present in the combined condition. Residual RVOT obstruction should
now be preventable in most instances. On the other
hand, a disturbing problem is the high incidence of residual left AV valve regurgitation and the need for late
prosthetic valve replacement. Although technical improvements in reconstruction of the common AV valve
are certainly possible, the complex pathology of the
valve will most likely continue to require prosthetic replacement in some patients.
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Discussion
DR.GEORGE A. TRUSLER (Toronto, Ont, Canada): I had an opportunity to review this manuscript before the meeting, and congratulate the authors on their fine effort. In general, the experience of my colleagues and myself in Toronto is very similar.
From 1964 to 1985, we repaired complete AV canal and tetralogy in 14 children ranging from 13 months to 14 years old. All
but 1 had a type C canal. We used a single patch in 6 and a
double patch in 8. A transannular patch was applied in 8 children. We encountered only l child who required treatment of
peripheral pulmonary stenosis. Patching was used.
There were 2 early deaths, both due to left ventricular failure,
and 1 late death, which was due to dehiscence of the valve from
the patch. Two children have needed reoperation later, 1 for
mitral valve replacement and the other, pulmonary valve replacement. Thus, like the authors, we found that patching the
right side and creating pulmonary incompetence did not create
a lot of problems in these patients.
Although there were no major differences in results using a
single-patch or double-patch technique, in this particular group
of patients I prefer the double patch. I insert a separate VSD
patch under the anterior bridging leaflet without cutting it. The
chance of subsequent dehiscence from the patch is almost eliminated. If there is insufficient exposure to close the anterior portion of the VSD securely, this can be completed through the
infundibular incision which is made for relief of the pulmonary
stenosis. Sutures in the upper border of the VSD patch are
passed through the leaflet and later used to secure the atrial
patch. In complete AV canal, subaortic stenosis may be unmasked after the repair, and the authors’ point about keeping
the patch well to the right in such a case is well taken. We have
not found this to be more frequent in patients with tetralogy.
I have two questions on technique. First, have the authors
tried the double patch for repair of type C canals? Second, I
noted in the manuscript, if I read it correctly, that they use
pericardium for the patch, and I wondered why they preferred
that material.
In our limited experience, subaortic stenosis and small
primum axial septal defects have not been more common when
the canal defect is associated with tetralogy, but we will certainly watch for them in the future.
Again I congratulate Dr. Vargas on his presentation and the
Boston group on their comprehensive study and fine results.
DR.GORDON DANIELSON (Rochester, MN): It is a great pleasure
to have the opportunity of discussing this fine paper. I congratulate Dr. Vargas on his clear presentation and congratulate
all of the authors on their low operative mortality for repair of
this difficult cardiac anomaly.
Two years ago we reviewed the results in 14 patients who
underwent correction of complete AV canal with tetralogy of
Fallot. Our conclusions are similar to those of the authors, with
a few minor differences.
We did make the incision in the anterior bridging leaflet directly over the ventricular septum without deviating it in any
way to account for the anterior displacement of the infundibular septum. Repair of the VSD was facilitated by using a patch
with an anterior extension, a type of dog ear anteriorly. We
found that our best results were achieved by placing most of the
patch in the regular way, and then suturing the anterior extension, as Dr. Trusler mentioned, through the ventriculotomy,
the distal incision in the RVOT through which the infundibular
resection is accomplished. This gives a very nice look at the
anterior portion of the septum, and the sutures can be placed
appropriately. The patch is made slightly redundant to eliminate subaortic obstruction.
Dr. Vargas, do you think that the incidence of early and late
valve replacement and reoperation that you mentioned could
be related to the oblique incision in the anterior septal leaflet?
I noted in the manuscript that pericardium was used to close
the VSD. I am intrigued by this because pericardium would
seem to have a real advantage in contouring itself for this long
and devious suture line. Have you noticed any late complications such as aneurysms or obstructions related to the use of
pericardium in this application?
Again, I congratulate the authors on their important contribution.
DR. VARGAS: I thank the discussants for their comments and
remarks.
Dr. Trusler, although we do not think that the type of patch
material used for closure of the AV defect is of particular importance, we have continued to use pericardium because of its
availability and ease of handling. Recently, we have begun to
pretreat the pericardial patch with 1.5%glutaraldehyde to facilitate tailoring of the pericardium, which is particularly useful
when there is a large anterior extension of the VSD.
In our clinical experience we have not observed a hemodynamically significant subaortic obstruction after repair. However, analysis of the postmortem material clearly identifies the
potential for this complication.
Dr. Danielson, concerning the high incidence of early and
late postoperative left AV valve regurgitation, we found a close
correlation between AV valve dysfunction and the anatomical
abnormalities already described. We do not believe, nor is it our
experience in the early and late follow-up of patients with
isolated complete AV canal, that division and reattachment of
the anterior AV valve leaflet adds to valvular morbidity.