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Document 6594758

MHBD054-CH68[1231-1240].qxd 11/10/06 13:13 Page 1231 p-mac292 27A:MHBD054:Chapters:CH-68: TechBooks
CHAPTER
68
HYPOPLASTIC LEFT
HEART SYNDROME
Peter J. Gruber, Thomas L. Spray
DEFINITION
Hypoplastic left heart syndrome includes a wide spectrum
of anatomic abnormalities with the common feature of left
ventricular hypoplasia and hypoplasia of the ascending
aorta. At one end of the spectrum there may be some mild
left ventricle hypoplasia, mild aortic stenosis, and aortic
coarctation. At the other end of the spectrum, however,
there is complete absence of the left ventricle, aortic atresia, or an association with an interrupted aortic arch. All
these neonates present a serious challenge to congenital
heart surgeons, cardiologists, and their families; the condition is uniformly fatal in the absence of intervention. There
is now little argument about the utility of staged operative
repair in these children as a result of continued improvements in operative techniques and perioperative care.
HISTORICAL HIGHLIGHTS
Therapy for HLHS has been one of the great successes
of treatment of congenital heart disease (CHD). Before
KEY CONCEPTS
●
●
●
Epidemiology
● Hypoplastic left heart syndrome (HLHS) accounts
for 5 percent of all congenital heart anomalies and
is responsible for 25 percent of cardiac deaths in
the first week of life. Its incidence is 1.8 in 10,000
live births, with 25 percent of cases showing associated noncardiac malformations and 5 percent showing chromosomal abnormalities.
Morphology
● HLHS includes a wide spectrum of anatomic abnormalities with the common feature of hypoplasia of
the left ventricle (LV) and the ascending aorta. At
one end of the spectrum there may be some mild LV
hypoplasia, mild aortic stenosis, and aortic coarctation. At the other end there is complete absence of
the LV, aortic atresia, and aortic arch interruption.
Pathophysiology
● Systemic venous return is channeled via an interatrial communication to the right ventricle (RV) and,
through the pulmonary artery and patent ductus
arteriosus (PDA), to the systemic and pulmonary circulations. Balanced physiology ensues, with QP:QS
●
●
●
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varying according to systemic and pulmonary vascular resistance as well as the unrestrictive nature
of an atrial septal defect (ASD).
Clinical features
● HLHS is uniformly fatal if it is not treated as a result
of ductal closure in the postnatal period. Evidence
of pulmonary overcirculation is provided by QP:QS
on clinical examination.
Diagnosis
● Prenatal echocardiography can be used to detect
unbalanced ventricles as early as 20 weeks of
gestational age. Postnatal echocardiography readily
establishes the diagnosis and guides medical and
surgical decision making.
Treatment
● Prostaglandin E1 (PGE1) infusion is the cornerstone
of early resuscitation, coupled with balloon atrial
septostomy in case of restrictive ASD. A three-stage
single-ventricle palliation approach has been
adopted by most centers. The first stage involves
aortic arch reconstruction and establishment of a
reliable source of pulmonary blood flow, and the
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●
PART III ● CONGENITAL CARDIAC SURGERY
second and third stages consist of sequential partitioning of the systemic and pulmonary circulations.
Transplantation has been used as the initial approach
or, more commonly, for those who fail palliative
strategy. In high-risk neonates, initial palliation with a
hybrid approach (stenting of coarctation and pulmonary arterial banding) should be considered.
Outcomes
● Operative survival of stage I Norwood palliation
depends on several variables, including anatomic
the 1980s, HLHS was a uniformly lethal condition.
Over the last 25 years, palliation of HLHS has become a
standard operation in nearly all institutions. In 1952,
Lev1 first described maldevelopment of the left-sided cardiac structures in combination with a small ascending
aorta and transverse arch. By 1958, Noonan and Nadas2
had defined the syndrome further to describe a variety of
cardiac malformations of left heart structures. The first
report of any attempt to palliate a patient with mitral
atresia was by Redo and associates,3 who in 1961 performed an atrial septectomy, using inflow occlusion
through a right thoracotomy; the patient died soon after
the operation. In 1968, Sinha and coworkers4 outlined
management principles that remain in use today that
include creation of an unobstructed atrial communication, unrestricted ductal flow, and control of pulmonary
blood flow. Cayler and colleagues5 described an anastomosis between the right pulmonary artery (PA) and the
ascending aorta with banding of both right and left pulmonary arteries. Interestingly, 35 years later, PA banding
is being employed in certain centers for selected children
who present with a medical or anatomic situation that is
not suitable for stage 1 Norwood reconstruction; this
first-stage hybrid procedure involves stenting the ductus
arteriosus and atrial septal defect and bilateral PA
bands.6,7 Litwin, Mohri, and others all performed operations that were variations of these principles that were
unsuccessful but contributed to the development of the
knowledge of the disease and its palliation.8,9 In 1977,
Doty and Knott10 described primary reconstruction that
included atrial septation and a right atrium (RA) to PA
Fontan circuit. Again, though no patients survived, this
experience confirmed that one-stage reconstruction
would not be successful because of high neonatal pulmonary vascular resistance (PVR).10 Levitsky, Behrendt,
and others described multiple possible surgical procedures; although the procedures demonstrated no longterm success,11,12 they established the principle of staged
reconstruction as first described for tricuspid atresia by
Fontan and Kreutzer, with a strategy of initial palliation
followed by later separation of the systemic and pulmonary circulations.13,14 However, it was Norwood who
provided the seminal contribution as the first to palliate
infants successfully in 1980 and in 1983 with the first
report of a successful staged approach.15,16 The Norwood
factors (diameter of ascending aorta, operative
weight, restrictive ASD, associated anomalies),
and nears 80 percent in several series. Operative
mortality between 5 and 10 percent has been
observed for second- and third-stage palliation.
Long-term complications [ventricular failure, atrioventricular (AV) valve regurgitation, arrhythmias,
and protein-loosing enteropathy, among others]
dictate a late prognosis and the need for reintervention or transplantation.
procedure remains the primary reconstructive approach
to this day.
EMBRYOLOGY AND ANATOMIC
CONSIDERATIONS
From a molecular standpoint, the developmental mechanisms that underlie HLHS are obscure, as there are no
mutations that have been associated robustly with this
part of the heart. Despite the existence of rare family
clustering of HLHS, linkage analysis has been unproductive.17–20 However, embryologically, there are clues. The
severe hypoplasia of left heart structures is probably a
consequence of limited flow during development secondary to a primary abnormality of either left ventricular
inflow or left ventricular outflow. Primary defects of
myocardial growth are unlikely to be a mechanism for
this disease, since the myocardium appears normal.21,22
Additionally, in approximately 5 percent of patients with
aortic atresia, an unrestrictive ventricular septal defect
coexists, and in such cases, there is nearly always normal
development of the left ventricle and the mitral valve.
Patients can be categorized on the basis of atrioventricular and semilunar valvular morphology into three
primary subsets: (1) aortic atresia with mitral atresia (40
percent), (2) aortic stenosis with mitral stenosis (30 percent), and (3) aortic atresia with mitral stenosis (30 percent) (Fig. 68-1). Aortic stenosis with mitral atresia is
rare. HLHS variants include a malaligned AV canal, a
double-outlet right ventricle with mitral atresia, tricuspid
atresia with transposed great arteries, and a univentricular heart with aortic stenosis. There is frequently leftward
and posterior deviation of the septal attachment of the
septum primum, but this is unlikely to be a common
developmental mechanism, since it is seen commonly in
other CHD patients. Usually, the superior and inferior
venae cavae (SVC and IVC) are connected normally to
the right atrium, though in about 15 percent of these
patients a left SVC draining to the coronary sinus is present. Other structural abnormalities of the heart are rare,
with less than 5 percent of patients demonstrating AV
valvular dysplasia. Also rare (less than 5 percent) is an
association with abnormalities of pulmonary venous
return or aortic arch interruption. Abnormalities in brain
Chapter 68 ● Hypoplastic Left Heart Syndrome
1233
of a large number of mutations that affect valvular development. This argues for a complex early multifactorial
event or, more likely, a transient early insult.
EPIDEMIOLOGY
Figure 68-1 Anatomy and physiology of hypoplastic left
heart syndrome. Hypoplastic left-sided structures force pulmonary venous blood to flow from the left atrium through
the interatrial communication to the right atrium (downward
arrow). Blood from the right ventricle flows both to the pulmonary circulation via the pulmonary artery (upward arrow)
and to the systemic circulation via the ductus arteriosus.
Maintenance of ductal patency is critical for survival. The
surgical principles of repair aim at maintaining this stable
physiology. (Reprinted with permission from Gruber P, Spray
T, et al. Hypoplastic left heart syndrome. In Kaiser LK, Kron
IL (eds.), Mastery of cardiothoracic surgery, 2nd ed.
Philadelphia: Lippincott Williams & Wilkins, 2006:936.)
development increasingly are being associated with children with severe congenital heart disease and may define
a high-risk group for operative repair.23 The pulmonary
vascular tree also harbors abnormalities with an increase
in number of vessels as well as muscularity.24,25
PATHOPHYSIOLOGY
A normal fetus has a parallel circulation that adequately
supports single-ventricle physiology before birth. Three
communications (the ductus venosus, foramen ovale,
and ductus arteriosus) shunt oxygenated placental blood
largely past the hepatic and pulmonary beds to supply
the splanchnic circulation. Hypoplastic left heart syndrome is well supported in this situation, and as a result,
it is rarely a cause of fetal demise. Hypoplastic left heart
syndrome is probably a secondary result of early obstructive lesions of either mitral or aortic valvular development. This has been supported in animal models of
mitral or aortic stenosis with resulting left ventricular
hypoplasia.22 However, the primary cause of the obstructive flow lesion that leads secondarily to HLHS is
unknown. Interestingly, there are no known genetic animal models that recapitulate HLHS despite the existence
Hypoplastic left heart syndrome is a uniformly fatal disease if it is not treated. It represents 5 percent of all cases
of CHD and is responsible for nearly 25 percent of cardiac deaths in the first week of life. Among 10,000 live
births, approximately 1.8 will be born with HLHS, with a
slight male predominance. Of these, 25 percent also will
have a noncardiac anomaly, and 5 percent a chromosomal
abnormality (most typically trisomy 13, 18, or 21).
Syndromic lesions are rare, but among these patients,
Turner’s syndrome(monosomy X) is the most common.
The recurrence risk is 2.2 percent for one affected sibling
and 6 percent for two affected siblings, suggesting a
genetic predisposition but arguing against a simple effect.
CLINICAL PRESENTATION
The presentation of infants with CHD has changed dramatically over the last 10 years. In most large centers, the
majority of patients are identified through prenatal
echocardiography; this early identification has not been
correlated consistently with a better outcome. Although
some tachypnea and mild cyanosis may be present, it is
not until the ductus arteriosus begins to close that children with HLHS manifest evidence of impaired systemic
perfusion with pallor, lethargy, and diminished femoral
pulses. Cardiac examination reveals a dominant right
ventricular impulse, a single second heart sound, and
often a nonspecific soft systolic murmur. Electrocardiographic examination reveals right atrial enlargement and
right ventricular hypertrophy. Chest x-ray occasionally
shows mild cardiomegaly and increased pulmonary vascular markings.
DIAGNOSIS
Physical examination of children with HLHS is usually
normal. The examination is determined by the underlying anatomy as well as the chronicity of the disease (ductal closure and PVR). Poor perfusion, weak distal pulses
that may not be present because of the size of the ductus,
acidosis, and a sepsis-like picture may confound the diagnosis. In the absence of risk factors or laboratory findings
consistent with sepsis, one should look for left-sided
obstructive lesions.
There are no specific laboratory indicators of HLHS.
These patients usually exhibit normal values. With ductal
closure and malperfusion, end-organ compromise may
be reflected by altered hepatic and renal function tests.
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At 20 weeks of gestation, a fetal echocardiogram
allows reasonable visualization of the cardiac structures.
It is neither feasible nor cost-effective to screen all pregnancies; a selective approach therefore is taken currently
in which only mothers at high risk are screened. Frequently, a ventricular size discrepancy is the first hint of
impending problems. Certainly, the presence of an
intact or restrictive atrial septum should prompt term
high-risk delivery in an institution where an urgent
postdelivery atrial septectomy can be performed safely
and rapidly. The use of prenatal screening improves the
prenatal condition of the child but may not translate
into an improved outcome (at least in cases of transposition of the great arteries or HLHS).26,27 After delivery,
the infant should undergo two-dimensional and
Doppler echocardiography to define anatomy to an
extent sufficient for medical and surgical decision making. It is important to distinguish HLHS from other
diseases that may mimic certain of its features, as their
management differs.
Chest radiography often demonstrates mild cardiomegaly and excessive pulmonary blood flow. Head
ultrasound should be obtained in all patients to rule out
intracranial hemorrhage and minimize the risks of
heparinization and circulatory arrest. Patients with medical necrotizing enterocolitis should have a 7-day course
of intravenous antibiotics before first-stage palliation.
MEDICAL THERAPY
Regardless of the anatomic subtype, preoperative stabilization is critical to the ultimate outcome of patients
with HLHS. Nearly all patients with suspected HLHS
are transported to the authors’ center on PGE1 at a dose
of 0.01 to 0.025 g/kg/min. Two clinically important
dose-dependent side effects of PGE1 are hypotension
and apnea, though they are infrequently clinically important. Umbilical arterial and umbilical venous lines are
used for monitoring and central access in most patients.
Most infants can ventilate with a natural airway and
indeed often have more favorable hemodynamics while
extubated. Supplemental oxygen generally should be
avoided as it will act as a pulmonary vasodilator, decreasing PVR, increasing Qp:Qs, and thus decreasing systemic
perfusion. Inotropic support is required in patients who
have had a perinatal insult but otherwise is rarely necessary. The goal of these maneuvers is to get the patient to
the operating room in as stable condition as possible.
SURGICAL THERAPY
There are two primary therapies for HLHS: (1) staged
reconstructive surgery leading to a modified FontanKreutzer procedure and (2) heart transplantation. Heart
transplantation is discussed in detail in Chapter 80; this
chapter focuses on staged reconstructive surgery.
Over the last 20 years, the Norwood procedure has
evolved and become the standard approach in nearly all
institutions that care for neonates and infants with
HLHS. There are three primary goals to first-stage palliation: (1) establishment of unrestricted interatrial
communication to provide complete mixing and avoid
pulmonary venous hypertension, (2) establishment of a
reliable source of pulmonary blood flow, allowing for the
development of pulmonary vasculature and minimization of volume load on the single ventricle, and (3) provision of unobstructed outflow from the ventricle to the
systemic circulation.
The Children’s Hospital of Philadelphia offers surgical palliation to nearly all patients with HLHS, including
very low birth weight infants and those with nonlethal
genetic syndromes.
Stage I reconstructive procedure
Two perfusion techniques can be used for first-stage palliation: deep hypothermic circulatory arrest (DHCA)
and selective antegrade continuous cerebral perfusion.
At present, there is no consensus on the superiority of
one approach over the other, although DHCA is used
more commonly.
The child is brought to the operating room and ventilated on room air, with care taken to avoid hyperventilation. A full midline sternotomy is performed, and the
thymus is removed in its entirety, with care being taken to
avoid the phrenic nerves. The pericardium is opened, and
an obligatory mediastinal inspection is performed to confirm the echocardiographic findings, especially to identify
abnormalities of the aortic arch and coronary arteries. The
ascending and descending aorta, head vessels, ductus arteriosus, and pulmonary arteries are mobilized extensively,
with care taken to preserve the integrity of the recurrent
laryngeal nerve. No attempt is made to dissect the systemic
veins. Purse-string sutures are placed in the proximal main
pulmonary artery and generously around the right atrial
appendage, through which heparin is administered. A previously thawed pulmonary homograft hemiartery patch is
trimmed in an extended arrowhead shape and set aside.
After the activated clotting time reaches 300 s, the patient
is cannulated, with the arterial cannula inserted at the base
of the main pulmonary artery and a single venous cannula
inserted in the right atrium (Fig. 68-2). Cardiopulmonary
bypass is initiated, and tapes are brought down around the
branch pulmonary arteries. The patient is cooled to 18C
over 15 min, during which time any remaining dissection is
performed. A side-biting clamp is placed on the innominate artery, and a Gore-Tex graft (usually 4.0 mm for
patients over 3.2 kg) is anastomosed in an end-to-side fashion. The clamp is removed, and flow is assessed. If blood
does not flow easily out of the open shunt, the anastomosis
should be revised. A large hemoclip is placed gently to
occlude the shunt temporarily.
On initiation of circulatory arrest, tapes are brought
down around the head vessels and a spoon clamp is
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connection is performed using interrupted fine polypropylene sutures to connect the root of the great vessels.
Next, the arch is reconstructed using the homograft patch,
carrying this suture line down to complete the DamusKaye-Stansel (DKS) anastomosis proximally (Fig. 68-3).
The distal Blalock-Taussig shunt anastomosis is performed
Figure 68-2 Incisions for hypoplastic left heart syndrome
first-stage palliation. Cannulation is performed with an arterial
cannula in the base of the main pulmonary artery and a single venous cannula through a generous purse string around
the right atrial appendage. Subsequent incisions, as
described in the text, are indicated by the dotted lines. The
patch for aortic augmentation and completion of the aortopulmonary anastomosis is fashioned from a pulmonary
homograft (insert). (Reprinted with permission from Gruber
P, Spray T, et al. Hypoplastic left heart syndrome. In Kaiser
LK, Kron IL (eds.), Mastery of cardiothoracic surgery, 2nd ed.
Philadelphia: Lippincott Williams & Wilkins, 2006:938.)
placed on the descending aorta distal to the ductal insertion site. Cardioplegia is administered retrograde through
a side port on the arterial cannula. After the patient’s
blood volume has been drained into the reservoir, all
cannulas and PA tapes are removed. The ductus arteriosus is ligated on the PA side and divided on the aortic
side. The atrial septum is excised completely, working
through the atrial purse-string sutures. Though this is
seldom necessary, visualization can be improved through
a right atriotomy. Next, the main PA is divided close to
the branch PAs, and the defect in the distal main PA segment is closed with an oval homograft patch or primarily,
in a vertical fashion. At a point beginning immediately
adjacent to the divided main pulmonary artery (MPA)
the diminutive aorta is incised medially and the aortotomy is carried superiorly along the underside of the
transverse arch through the ductal insertion site to a
point approximately 1 cm distal to it. Importantly, all
redundant ductal tissue is excised and the coarctation
shelf is debrided (alternatively, the segment is excised
and the isthmus and proximal descending aorta are
reanastomosed). The proximal-aortic-to-proximal-PA
A
B
Figure 68-3 Damus-Kaye-Stansel anastomosis (DKS) and
aortic arch reconstruction. After complete excision of ductal
tissue and an interrupted anastomosis of the medial aspects
of the aorta and the main pulmonary artery, the homograft
patch is used to augment the hypoplastic aortic arch and
complete the DKS. The modified right Blalock-Taussig shunt
is completed from the innominate artery to the right pulmonary artery (A). An alternative approach (Sano modification, B) substitutes a right ventricle–pulmonary artery
Gore-Tex conduit for the Blalock-Taussig shunt. (Reprinted
with permission from Gruber P, Spray T, et al. Hypoplastic
left heart syndrome. In Kaiser LK, Kron IL (eds.), Mastery of
cardiothoracic surgery, 2nd ed. Philadelphia: Lippincott
Williams & Wilkins, 2006:938–939.)
1236
to the origin of the right PA, although some prefer to do
this with rewarming after removal of the aortic crossclamp. The arch is infused with cold saline to assess the
geometry and rule out kinking or residual obstruction,
the atrium is infused with cold saline to de-air, and the
cannulas are replaced. Cardiopulmonary bypass is begun,
and the patient is warmed to 37C over 22 min. It is
important at this point to assess prompt and equivalent
filling of the coronary distributions, and any perfusion
defect should be addressed immediately with revision of
the aortopulmonary anastomosis. During warming,
obvious bleeding should be controlled. The average
duration of hospitalization is 7 to 21 days, with the limiting factor often being the establishment of adequate oral
intake of formula.
A
Stage II procedure
Two important observations by Norwood and colleagues
early in the reconstructive experience prompted the institution of an intermediate stage between the initial palliation and the completion of a total cavopulmonary
connection. The first observation was that there was timerelated interstage mortality; the second was that the
chronic volume load of a systemic-to-pulmonary shunt
could create diastolic ventricular dysfunction. Thus, an
intermediate stage was initiated as either a bidirectional
cavopulmonary (Glenn) shunt or a hemi-Fontan procedure (see Chapter 69). A bidirectional cavopulmonary
anastomosis sets the patient up for an extracardiac conduit, whereas a hemi-Fontan sets the patient up for a lateral tunnel completion Fontan. No long-term data prove
the superiority of one approach over the other. In general,
at approximately 4 to 6 months of age, stage I survivors
are catheterized to evaluate both pressures throughout
the heart and the anatomy of the pulmonary arteries. The
use of a cavopulmonary anastomosis before 3 months of
age usually is associated with increased hypoxia and upper
body venous congestion. The technique for a bidirectional cavopulmonary anastomosis is fairly standard (Fig.
68-4A). The approach is through a reoperative median
sternotomy during which care is taken in regard to the
dissection of the neoaorta, which is often adherent to the
left side of the sternum and somewhat fragile. The patient
is cannulated in a standard fashion with an arterial cannula
in the neoaorta, a small angled venous cannula in the
SVC, and a straight cannula in the body of the RA.
Although it is possible to perform this procedure without
cardiopulmonary bypass (CPB), the authors find it considerably easier to use CPB and believe that the anatomic
result is improved. Extracorporeal circulation is begun,
and a tape is brought down around the SVC cannula after
ligation and division of the azygous vein. The previous
shunt is divided and ligated near the innominate artery. A
vascular clamp is placed at the SVC-RA junction, and the
SVC is divided. The atrial portion is closed in two layers
with fine monofilament sutures. The PA is opened in the
superior portion and inspected carefully. If preoperative
B
Figure 68-4 Superior cavopulmonary anastomosis. A. The
bidirectional Glenn replaces the source of obligatory pulmonary blood flow from the Blalock-Taussig shunt to the
superior vena cava. B. The hemi-Fontan results in precisely
the same physiology but uses a single piece of homograft
to augment the pulmonary arteries, complete the superior
cavopulmonary anastomosis, and create the right
atrium–pulmonary artery dam simultaneously. (Reprinted
with permission from Gruber P, Spray T, et al. Hypoplastic
left heart syndrome. In Kaiser LK, Kron IL (eds.), Mastery of
cardiothoracic surgery, 2nd ed. Philadelphia: Lippincott
Williams & Wilkins, 2006:940–941.)
catheterization revealed pulmonary arterial stenosis, this is
addressed with pulmonary homograft patch augmentation. The SVC then is anastomosed to the superior aspect
of the right pulmonary artery as medially as possible
toward the left PA. The tape is removed from the SVC
cannula, and one or two right atrial lines are brought into
the mediastinum percutaneously from the right and
placed in the body of the right atrium. The patient is
weaned from CPB, and the SVC cannula is removed.
Modified ultrafiltration is performed, and during that
time, all suture lines are checked for hemostasis. At the
completion of modified ultrafiltration, the SVC pressure
can be measured directly. The SVC monitoring line is
removed, and the cannulation purse string is tied securely.
All cannulas are removed, and protamine is administered.
The chest is closed in a standard fashion, and the patient is
returned to the intensive care unit (ICU). In general,
these patients can be extubated soon after their return to
the ICU.
An alternative operative approach is the hemi-Fontan,
which the authors perform under deep hypothermic circulatory arrest. The details of this procedure are summarized in Fig. 68-4B and are described in Chapter 69. The
hemi-Fontan is performed under DHCA, using a piece
of folded homograft to augment the pulmonary arteries
and create the superior cavopulmonary anastomosis and
the RA-PA dam simultaneously. This dam subsequently
will be removed for the lateral tunnel completion Fontan
operation.
1237
aspect of the pulmonary arteries, angled slightly medially
to the SVC. Practically, the angled nature of the superior
portion of the conduit augments the pulmonary confluence from the right to the left PA (Fig. 68-5A). The conduit is infused with saline to de-air, and the patient is
weaned off CPB. The SVC cannula is removed, and a
period of modified ultrafiltration is begun. All suture
Stage III procedure
Between ages 2 and 5, usually on the basis of a combination of the patient’s weight, growth characteristics, and
arterial saturations, the patient is reimaged by echocardiography and occasionally with cardiac catheterization.
If there are no anatomic issues to be addressed with
catheter-based intervention (e.g., distal arch coarctation), the patient is referred for Fontan reconstruction
via an extracardiac conduit or a lateral tunnel completion
Fontan. For the extracardiac conduit, DHCA or continuous bypass with or without aortic cross-clamping is
employed, whereas DHCA is used for the lateral tunnel.
The approach is through a reoperative median sternotomy. The following material describes the basic steps
of the extracardiac Fontan.
The patient is cannulated bicavally in a standard fashion, and an arterial cannula is placed high in the aortic
reconstruction. Cardiopulmonary bypass is begun, and
tourniquets are applied around the caval cannulas. A vascular clamp is placed at the IVC-RA junction, and the
IVC is divided. The atrial portion is closed partially in
two layers with fine monofilament sutures. The conduit
(18- to 22-mm Gore-Tex) is trimmed to the appropriate
length to avoid compression of the right pulmonary vein
(which typically is shorter than one might expect), and a
4-mm fenestration is punched in the medial aspect near
the IVC portion. The IVC-conduit anastomosis is completed with monofilament sutures, followed by a side-toside anastomosis of the remaining cardiac portion of the
IVC opening with the exterior conduit, leaving a rim of
conduit around the fenestration. Next, the PAs are
opened in the inferior portion and inspected directly. If
preoperative studies revealed any pulmonary arterial
stenosis and the beveled end of the Gore-Tex conduit
will not span the area of stenosis, this situation is
addressed with pulmonary homograft patch augmentation. The conduit then is anastomosed to the inferior
A
B
Figure 68-5 Fontan completion. A. The extracardiac
Fontan uses a Gore-Tex tube graft to channel inferior vena
cava (IVC) blood outside the heart to the pulmonary circuit.
A 4-mm fenestration is fashioned between the remnant cardiac portion of the IVC and the side of the conduit. B. The
lateral tunnel Fontan baffles blood from the IVC along the
lateral aspect of the atrium inside the heart to the pulmonary
circuit. The homograft dam created during the hemi-Fontan
is excised to create continuity with the pulmonary arteries.
Fenestration patency has proved more reliable in this procedure than in the extracardiac Fontan. (Reprinted with permission from Gruber P, Spray T, et al. Hypoplastic left heart
syndrome. In Kaiser LK, Kron IL (eds.), Mastery of cardiothoracic surgery, 2nd ed. Philadelphia: Lippincott Williams &
Wilkins, 2006:943–944.)
1238
lines are checked for hemostasis. At the completion of
modified ultrafiltration, the SVC pressure is measured
directly with a transthoracic line. An additional monitoring line is placed in the right atrium. All cannulas are
removed, and protamine is administered. The chest is
closed in a standard fashion, and the patient is returned
to the ICU. In general, these patients can be extubated
soon after their return to the ICU.
An alternative operative approach is the lateral tunnel
Fontan, which the authors perform under deep
hypothermic circulatory arrest. The technical details of
this procedure are summarized in Fig. 68-5B. The lateral
tunnel Fontan is performed under DHCA, using a piece
of fenestrated Gore-Tex patch to baffle blood from the
IVC to the pulmonary arteries. The previously constructed PA-RA homograft dam is excised. There are no
long-term data suggesting the superiority of one technique over the other, but the lack of an atrial suture line
with the extracardiac Fontan has led to a preference for
its use when extensive PA reconstruction is necessary.
OUTCOMES
Despite continued improvement in outcomes, patients
with HLHS continue to present a formidable challenge.
The authors’ group reported the results of the 15-year
Children’s Hospital of Philadelphia (CHOP) experience
with 840 patients undergoing stage I surgery for HLHS
between 1984 and 1999. The 1-, 2-, 5-, 10-, and 15year survivals for the entire cohort were 51 percent, 43
percent, 40 percent, 39 percent, and 39 percent, respectively. A later era of stage I palliation was associated with
significantly improved survival, with 3-year survival for
patients undergoing stage I reconstruction from 1995 to
1998 of 66 percent versus 28 percent for those undergoing surgery between 1984 and 1988.28 More recent
studies have shown further improvement and demonstrated that the variability in outcome is influenced by
anatomy. One retrospective study of risk factors for operative and 1-year mortality in 158 patients who underwent the Norwood procedure demonstrated that the
diagnosis of HLHS is not a predictor of mortality.
HLHS was present in 102 patients, and other forms of
functional single ventricle with systemic outflow tract
obstruction were observed in the remaining 56.
Operative survival for the entire cohort was 77 percent
(78 percent for patients with HLHS and 75 percent for
patients with other diagnoses). Birth weight, associated
cardiac anomalies, total support time, and the need for
extracorporeal membrane oxygenation (ECMO) or ventricular assist device (VAD) support were predictors of
operative mortality. Survival to 1 year was 86 percent
after successful first-stage palliation, although the presence of an extracardiac anomaly, a genetic syndrome, or
an additional cardiac defect was predictive of worse survival in the first year of life.29
Additional perioperative or operative treatment strategies may improve morbidity and mortality rates. A consecutive series of 115 patients who underwent stage I
palliation from Milwaukee identified the risk factors for
mortality and the impact of new treatment strategies.
Between 1996 and 2001, hospital survival was 93 percent compared with 53 percent for the time interval
between 1992 and 1996. Survival to stage II palliation
also was improved significantly, increasing from 44
percent to 81 percent. Anti-inflammatory treatment
strategies, continuous saturated venous oxygen (Svo2)
monitoring, and the use of phenoxybenzamine were factors favoring survival to stage II.30
Another approach has been the development of home
surveillance programs. One study compared patients discharged before the initiation of home surveillance with
those discharged with an infant scale and a pulse oximeter. The parents maintained a daily log of weight and
arterial oxygen saturation according to pulse oximetry
and were instructed to contact their physicians in case of
arterial oxygen saturation less than 70 percent according
to pulse oximetry, an acute weight loss of more than 30
g/24 h, or failure to gain at least 20 g during a 3-day
period. Interstage mortality was 15.8 percent in the historic group and 0 percent in the monitored group, suggesting that monitoring programs may provide significant
benefit in reducing interstage attrition.31
Recent reports advocate that an RV-PA conduit
(rather than a modified Blalock-Taussig shunt) as reintroduced by Sano and colleagues may improve the outcome after stage I reconstruction.32–34 However, further
studies have indicated the need for caution before broad
adoption of the RV-PA conduit. The CHOP group compared the outcomes of all neonates who underwent a
stage I reconstruction between 2002 and 2004 with the
use of the RV-PA conduit and modified Blalock-Taussig
shunt. In all, 149 infants underwent a stage I reconstruction for HLHS or its variants. There was no difference in
surgical mortality, time to extubation, or length of hospital stay between the two techniques. Although there was
no difference in overall mortality, patients with an RVPA conduit required more conduit-related reinterventions and returned earlier for stage II reconstruction.35
Patients who have completed staged palliation for
HLHS frequently require reintervention. A study examining these reinterventions during a 6-year period
between 1995 and 2001 found that 123 procedures were
performed in 71 patients. The median time from Fontan
completion to reoperation was 3.6 years, with indications
for reintervention including arrhythmia, cyanosis, exercise intolerance, protein-losing enteropathy (PLE), atrioventricular valve (AVV) regurgitation, and other
indications. The procedures included pacemaker insertion or revision (48 percent), reinclusion of previously
excluded hepatic veins (13 percent), revision to a lateral
tunnel or extracardiac conduit pathway (11 percent), cardiac transplantation (7 percent), enlargement or creation
of a baffle fenestration (5 percent), isolated AVV repair or
replacement (2 percent), and other procedures (14 percent). There were five early and five late deaths. Hospital
mortality was greatest among patients undergoing cardiac transplantation (44 percent), who accounted for 80
percent of the early deaths. Most reinterventions can be
performed with minimal morbidity and mortality.
However, patients who require cardiac transplantation
after a Fontan procedure fare poorly.36
For high-risk infants, some have advocated catheterbased hybrid approaches (stage I: ductal stenting and PA
banding; stage II: septectomy, arch augmentation, and
cavopulmonary anastomosis; stage III: catheter-based
Fontan completion). One report of the hybrid stage I
procedure in 14 high-risk neonates between 2003 and
2005 demonstrated promising results, with a 78.5 percent hospital survival rate. Eight patients underwent
stage II procedures, with two operative deaths. These
techniques may be limited in certain anatomic subsets,
such as patients with aortic atresia in which preductal retrograde coarctation is a significant problem.6,37
The results from stage III palliation with Fontan circulation also continue to improve. The authors’ group
reviewed the outcomes of 332 patients: 281 with a lateral tunnel and 51 with an extracardiac Fontan procedure. There was a 93.4 percent hospital survival rate, and
by questionnaire, 94.6 percent of guardians described
their children’s overall health as excellent or good and
5.4 percent reported it as fair or poor. School performance was described as above average in 30.2 percent,
average in 39.9 percent, and below average in 29.8 percent. With regard to cardiac functional status, 34.2 percent responded that their children had no limitations to
physical activity, 52.5 percent reported a slight limitation, 12.1 percent reported a significant limitation, and
1.2 percent reported a severe limitation. Although these
data suggest that acceptable survival outcomes have been
1239
observed at intermediate follow-up of the Fontan operation, much work remains to be done.38
In comparing outcomes of extracardiac conduit and
lateral tunnel Fontan connections, the results have been
conflicting. The Toronto group reported the results of
60 extracardiac conduit and 47 lateral tunnel total
cavopulmonary connections performed between 1994
and 1998. Overall operative mortality was 5.6 percent
and did not differ between groups. The lateral tunnel
group had a significantly higher incidence of postoperative sinoatrial node dysfunction, supraventricular tachycardia, and need for temporary postoperative pacing.
The median duration of ICU stay and the need for ventilatory support were longer in the lateral tunnel group.
Holter analysis showed a higher incidence of atrial
arrhythmias in the lateral tunnel group.39
However, other authors have not found support for
one technique over the other. For example, the
Charleston group found an incidence of sinus node dysfunction of 21 percent in the lateral tunnel group and 59
percent in the extracardiac group. No permanent pacemaker was placed in the lateral tunnel group, whereas
three were placed in the extracardiac group group.40
Another report from that group demonstrated identical
operative mortality and similar mean Fontan pressure,
transpulmonary gradient, and common atrial pressure in
the first 24 h after the completion of a cavopulmonary
connection. Duration of mechanical ventilation, ICU
stay, chest tube drainage, and hospital stay did not differ.
Again, extracardiac conduit patients had a higher incidence of sinus node dysfunction both in the postoperative period and at hospital discharge.41 These techniques
also appear equivalent in the situation of a failing Fontan,
with no hospital deaths and no arrhythmias at hospital
discharge or differences in mean duration of intubation,
inotropic support, ICU stay, hospital stay, or episodes of
acute postoperative arrhythmias.42
References
1. Lev M. Pathologic anatomy and interrelationship of
hypoplasia of the aortic tract complexes. Lab Invest
1952;1:61.
2. Noonan JA, Nadas AS. The hypoplastic left heart syndrome: An analysis of 101 cases. Pediatr Clin North Am
1958;5:1029.
3. Redo SF, Farber S, Gross RE. Atresia of the mitral valve.
Arch Surg 1961;82:696.
4. Sinha SN, Rusnak SL, Sommers HM, et al. Hypoplastic
left ventricle syndrome: Analysis of thirty autopsy cases in
infants with surgical considerations. Am J Cardiol 1968;
21:166.
5. Cayler GG, Smeloff EA, Miller GE Jr. Surgical palliation of
hypoplastic left side of the heart. N Engl J Med 1970;
282:780.
6. Bacha EA, Daves S, Hardin J, et al. Single-ventricle palliation for high-risk neonates: The emergence of an alterna-
tive hybrid stage I strategy. J Thorac Cardiovasc Surg
2006;131:163.
7. Pizarro C, Norwood WI. Pulmonary artery banding before
Norwood procedure. Ann Thorac Surg 2003;75: 1008.
8. Litwin SB, Friedberg DZ. Surgical management of a
neonate with interrupted aortic arch, transposition of the
great Arteries, and tricuspid atresia. Cardiovasc Dis 1975;
2:182.
9. Mohri H, Horiuchi T, Haneda K, et al. Surgical treatment
for hypoplastic left heart syndrome: Case reports. J Thorac
Cardiovasc Surg 1979;78:223.
10. Doty DB, Knott HW. Hypoplastic left heart syndrome:
Experience with an operation to establish functionally normal circulation. J Thorac Cardiovasc Surg 1977;74:624.
11. Behrendt DM, Rocchini A. An operation for the hypoplastic left heart syndrome: Preliminary report. Ann Thorac
Surg 1981;32:284.
1240
12. Levitsky S, van der Horst RL, Hasteiter AR, et al. Surgical
palliation in aortic atresia. J Thorac Cardiovasc Surg
1980;79:456.
13. Fontan F, Baudet E. Surgical repair of tricuspid atresia.
Thorax 1971;26:240.
14. Kreutzer G, Galindez E, Bono H, et al. An operation for
the correction of tricuspid atresia. J Thorac Cardiovasc
Surg 1973;66:613.
15. Norwood WI, Kirklin JK, Sanders SP. Hypoplastic left
heart syndrome: Experience with palliative surgery. Am J
Cardiol 1980;45:87.
16. Norwood WI, Lang P, Hansen DD. Physiologic repair of
aortic atresia-hypoplastic left heart syndrome. N Engl J
Med 1983;308:23.
17. Gelb BD. Molecular genetics of congenital heart disease.
Curr Opin Cardiol 1997;12:321.
18. Loffredo CA, Chokkalingam A, Sill AM, et al. Prevalence
of congenital cardiovascular malformations among relatives of infants with hypoplastic left heart, coarctation of
the aorta, and d-transposition of the great arteries. Am J
Med Genet A 2004;124:225.
19. McBride KL, Fernbach S, Menesses A, et al. A familybased association study of congenital left-sided heart
malformations and 5,10 methylenetetrahydrofolate
reductase. Birth Defects Res A Clin Mol Teratol 2004;
70:825.
20. McElhinney DB, Krantz ID, Bason L, et al. Analysis of
cardiovascular phenotype and genotype-phenotype correlation in individuals with a JAG1 mutation and/or Alagille
syndrome. Circulation 2002;106:2567.
21. Chen B, Bronson RT, Klaman LD, et al. Mice mutant for
Egfr and Shp2 have defective cardiac semilunar valvulogenesis. Nat Genet 2000;24:296.
22. Sedmera D, Hu N, Weiss KM, et al. Cellular changes in
experimental left heart hypoplasia. Anat Rec 2002;267:
137.
23. Forbess JM, Visconti KJ, Bellinger DC, et al.
Neurodevelopmental outcomes in children after the
Fontan operation. Circulation 2001;104:I127.
24. Macedo A, Pinto E, Ramos S, et al. Structural changes in
pulmonary vessels and coronary arteries in hypoplastic left
heart syndrome. Acta Med Port 1991;4:253.
25. Maeda K, Yamaki S, Kado H, et al. Hypoplasia of the small
pulmonary arteries in hypoplastic left heart syndrome with
restrictive atrial septal defect. Circulation 2004;110:II139.
26. Kumar RK, Newburger JW, Gauvreau K, et al.
Comparison of outcome when hypoplastic left heart syndrome and transposition of the great arteries are diagnosed
prenatally versus when diagnosis of these two conditions is
made only postnatally. Am J Cardiol 1999;83:1649.
27. Satomi G, Yasukochi S, Shimizu T, et al. Has fetal echocardiography improved the prognosis of congenital heart disease? Comparison of patients with hypoplastic left heart
syndrome with and without prenatal diagnosis. Pediatr Int
1999;41:728.
28. Mahle WT, Spray TL, Wernovsky G, et al. Survival after
reconstructive surgery for hypoplastic left heart syndrome:
A 15-year experience from a single institution. Circulation
2000;102:III136.
29. Gaynor JW, Mahle WT, Cohen MI, et al. Risk factors for
mortality after the Norwood procedure. Eur J Cardiothorac
Surg 2002;22:82.
30. Tweddell JS, Hoffman GM, Mussatto KA, et al. Improved
survival of patients undergoing palliation of hypoplastic
left heart syndrome: Lessons learned from 115 consecutive
patients. Circulation 2002;106:I82.
31. Ghanayem NS, Hoffman GM, Mussatto KA, et al. Home
surveillance program prevents interstage mortality after the
Norwood procedure. J Thorac Cardiovasc Surg 2003;126:
1367.
32. Sano S, Ishino K, Kado H, et al. Outcome of right
ventricle-to-pulmonary artery shunt in first-stage palliation
of hypoplastic left heart syndrome: A multi-institutional
study. Ann Thorac Surg 2004;78:1951.
33. Sano S, Ishino K, Kawada M, et al. Right ventriclepulmonary artery shunt in first-stage palliation of
hypoplastic left heart syndrome. Semin Thorac Cardiovasc
Surg Pediatr Card Surg Annu 2004;7:22.
34. Pizarro C, Malec E, Maher KO, et al. Right ventricle to
pulmonary artery conduit improves outcome after stage I
Norwood for hypoplastic left heart syndrome. Circulation
2003;108(Suppl 1):II155.
35. Tabbutt S, Dominguez TE, Ravishankar C, et al.
Outcomes after the stage I reconstruction comparing the
right ventricular to pulmonary artery conduit with the
modified Blalock Taussig shunt. Ann Thorac Surg 2005;
80:1582.
36. Petko M, Myung RJ, Wernovsky G, et al. Surgical reinterventions following the Fontan procedure. Eur J
Cardiothorac Surg 2003;24:255.
37. Galantowicz M, Cheatham JP. Lessons learned from the
development of a new hybrid strategy for the management
of hypoplastic left heart syndrome. Pediatr Cardiol 2005;
26:190.
38. Mitchell ME, Ittenbach RF, Gaynor JW, et al.
Intermediate outcomes after the Fontan procedure in the
current era. J Thorac Cardiovasc Surg 2006;131:172.
39. Azakie A, McCrindle BW, Van Arsdell G, et al.
Extracardiac conduit versus lateral tunnel cavopulmonary
connections at a single institution: Impact on outcomes. J
Thorac Cardiovasc Surg 2001;122:1219.
40. Dilawar M, Bradley SM, Saul JP, et al. Sinus node dysfunction after intraatrial lateral tunnel and extracardiac conduit
Fontan procedures. Pediatr Cardiol 2003;24:284.
41. Kumar SP, Rubinstein CS, Simsic JM, et al. Lateral tunnel
versus extracardiac conduit Fontan procedure: A concurrent comparison. Ann Thorac Surg 2003;76:1389.
42. Morales DL, Dibardino DJ, Braud BE, et al. Salvaging the
failing Fontan: Lateral tunnel versus extracardiac conduit.
Ann Thorac Surg 2005;80:1445.

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