Download Cryoablation Lesion with Atrial Arrhythmia after Fontan Operation

Fontan Operation
Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery
Fontan Operation
Introduction
Fontan operation
in 1971, Fontan et al, for tricuspid atresia
Technical modifications & advances
Better understanding of physiology
Improvement of the management
For a wide spectrum of complex
congenital heart diseases
Fontan Procedure
Concepts
• In patients with single ventricle physiology
1) Separate the systemic and pulmonary venous return
2) Establish the passive, unobstructed pathway between
the systemic venous return & pulmonary arteries
Physiologic benefits
1) Relief of cyanosis
2) Alleviation of ventricular volume overload
Fontan Operation
History
•
•
•
•
•
•
•
1971
1973
1979
1984
1988
1990
1990
Fontan
Kreuzer
Bjork
Kawashima
de Leval
Bridges
Giannico
Fontan operation
Modified Fontan op.(APC)
RA-RV connection
TCPS
TCPC with lateral tunnel
Fenestrated Fontan op.
Extra-cardiac Fontan op.
Right Heart Bypass (I)
Evolution
• Starr et al. 1943
– Canine nonfunctional RV model by cauterization
– Not result in systemic venous hypertension
• Bakos. 1950, Kagan. 1952, Donald et al. 1954
– Similar experiments
– RV is not absolutely necessary for pulmonary circulation
• Rodbard. 1948
– Low PAP in most animal species
– CVP is adequate driving force for pulmonary circulation
Right Heart Bypass (II)
• Robard & Wagner. 1949
– Proximal MPA ligation
– RA appendage to distal MPA
– Possibility of bypassing the RV,
when RA Pressure of 9-14 cm
H2O
* Functional TR - some
contribution to PBF(?)
Right Heart Bypass (III)
• Warden et al. 1954
– Staged obliteration of TV,
period of progressive RA
hypertrophy & dilatation
– Subsequent RA appendage
to MPA
* Some pumping action of
RA to PBF (?)
Right Heart Bypass (IV)
• Carlon et al. 1951
– Partial diversion of caval
blood to RPA
– After adding heparin,
long-term survival
• Glenn & Patino. 1954
– Similar experimental results
• Glenn et al. 1958
– First successful clinical trial
of classic cavopulmonary
shunt
Right Heart Bypass (V)
• Hurwitt et al, Shumacker.
1955
– Early clinical trial for TA
(RA to PA)
– Promising but no survival
• Harrison. 1962
– Staged RA to PA & ASD
closure
• Haller et al. 1966
– TV obliteration
– SVC to RPA side by side
Right Heart Bypass (VI)
• Fontan & Baudet. 1971
 Physiologic correction
– Classic Glenn shunt
– RA-RPA with aortic valve
homograft
– Closure of ASD
– Pulmonic valve homograft
– MPA ligation
Right Heart Bypass (VII)
• Kreutzer et al. 1973 :
– Anterior atriopulmonary
connection
– Direct RAA to MPA
– Pulmonic valve preserved
– No valve in IVC
• Ross & Somerville; Stanford
et al. 1973; Miller et al. 1974
– RAA to MPA using
homograft valve
Right Heart Bypass (VIII)
• Bowmann et al. 1978
– Atrioventricular
connection,
– Porcine valved conduit
• Bjork et al. 1979
– Atrioventricular
connection,
– Atrial tissue flap &
pericardial roof
Right Heart Bypass (IX)
• Doty et al. 1981
– Direct & posterior
atriopulmonary
connections
– Less susceptible
sternal compression
– Wide applications
Fontan Operation
Ten commandments
1. Minimal age of 4 years
2. Sinus rhythm
3. Normal caval drainage
4. Right atrium of normal volume
5. Mean pulmonary artery pressure ≤15 mmHg
6. Pulmonary vascular resistance < 4 clinical units/m2
7. Pulmonary artery to aorta diameter ratio ≥0.75
8. Normal ventricular function (EF ≥0.6)
9. Competent left atrioventricular valve
10. No impairing effects of previous shunt
Choussat, 1978
Now, not absolute but relative criteria
Fontan Operation
Selection of candidates
I. Age
• Tendency to earlier correction
Ventricular volume overload & cyanosis
Prevent late ventricular failure
• Optimal age : 2 - 4 years
II. Cardiac rhythm
• Preoperative NSR is not necessary
• Why?
– Preexisting AF : easy to control after Fontan
– Atrial contraction : turbulence & impeding flow
Fontan Operation
Selection of candidates
III. Pulmonary artery pressure
• Consideration of pulmonary blood flow and
pulmonary vascular resistance
IV. Pulmonary vascular resistance
• Absolute criteria
• Linear relation between PVR & survival
• < 2 Wood U : good
2 ~4
: risk
>4
: absolute contraindication
Fontan Operation
Selection of candidates
V. Pulmonary artery anatomy
• Size of the PA
– PAI ( Nakata Index ) > 250mm/m2
– McGoon ratio > 1.8
• More important factor than PA size itself
– Distal pulmonary vascular bed
– Arborization pattern of peripheral PA
• Other options
– Staging approach : BCPS, Hemi-Fontan
operation…
– Balloon dilatation : local stenosis
– Angioplasty at corrective operation
Fontan Operation
Selection of candidates
VI. Aortopulmonary collaterals
• Risk in previous BCPS or BT shunt
• Results of chronic hypoxemia as an adaptive mechanism
to deliver more pulmonary blood flow
• Origin from IMA, thyrocervical trunk
• Volume overload
pulmonary blood flow
L-R shunt
mismatch of Qp/Qs
Elevated PA & LA pressure with heart or respiratory failure
Prolonged tube drainage & pleural effusion
Adversely affect patient survival
Need transcatheter occlusion
Fontan Operation
Selection of candidates
VII. Ventricular function
• LVEDP
: < 25mmHg & associated with correctable causes such
as increased PBF, or AV valve insufficiency
Not a risk factor
• Ventricular hypertrophy
: Associated with increased PBF, subaortic stenosis,
PA banding, & increased age
Fontan Operation
Selection of candidates
VIII. AV valve insufficiency
• Remained stenosis & insufficiency are risk
factors , corrected at preliminary stage
operation if possible
IX. Anatomic morphology
• Systemic and pulmonary vein
: location & pathway
• Pulmonary venous obstruction
Fontan Operation
Criteria
Absolute contraindications
• Early infancy (age < 6-10 months)
• Severe hypoplasia of parenchymal pulmonary arteries
• Pulmonary vascular resistance > 4 clinical units
Relative contraindications
•
•
•
•
•
•
•
Age < 1-2 years
Pulmonary artery pressure > 15 mmHg
Ventricular end-diastolic pressure > 15 mmHg
Pulmonary vascular resistance 2-4 clinical units
Previous pulmonary artery banding
Substantial ventricular hypertrophy
Mitral or aortic valve insufficiency > mild
Sade et al., 1995
Fontan Operation
Surgical diseases
•
•
•
•
•
•
Tricuspid atresia
Double-inlet ventricles
Hypoplastic left heart syndrome
Many forms of heterotaxia syndrome
Pulmonary atresia with intact ventricular septum
Hypoplastic right or left ventricle in biventricular
hearts with VSD , with or without straddling AV valve
• DORV with noncommitted VSD
Right Heart Bypass
 By systemic venous bypass
Complete
Incomplete (partial) Glenn shunt
BCPS with or without additional PBF
Hemi-Fontan
Kawashima shunt(=TCPS)
Residual shunt
adjustable
fenestration
communication
 By connection
Atrioventricular
Atriopulmonary
Cavopulmonary
bidirectional or
unidirectional
Intracardiac(intraatrial) - lateral tunnel
Extracardiac
Unidirectional
Pre-Fontan Palliation
Before 6 months age
I. Systemic to pulmonary artery shunt
–
–
–
–
Central shunt
Pott’s shunt
Waterston shunt
Blalock-Taussig shunt
II. Pulmonary artery banding
– Preparation for Fontan : ventricular volume overload ↓
prevention of PVOD
– Trusler’s rule
– Adjust to PA pressure < 1/3 of systemic artery pr.
SaO2 > 75%
Pre-Fontan Palliation
Before 6 months age
III. Norwood operation
• In HLHS
• Control of pulmonary blood flow
– balance between SVR & PVR
– shunt size
IV. Palliative arterial switch opertion
• DILV with ventriculo-arterial discordance
• Tricuspid valve atresia with ventriculo-arterial
discordance complicated by a restrictive VSD & arch
obstruction
Pre-Fontan Palliation
After 6 months age
I. Bidirectional Cavo-Pulmonary Shunt
•
1958 , Glenn
•
1972 , Azzolina : 1st clinical report of BCPS
•
1985 , Hopkins : physiologic rationale for BCPS
: 1st clinical report of Glenn shunt
pre-Fontan staged operation
•
1989 , Mazzera : clinical applications as definitive
palliations
Pre-Fontan Palliation
BCPS
 Advantages
Improved oxygenation
Decreased volume loading on the single ventricle
Preservation of pulmonary vascular architecture
Decreased risk for PVD
Staged palliation & eliminate risk for Fontan
operation
Definite palliative procedure
Surgical procedure of choice after failed Fontan
operation
Pre-Fontan Palliation
BCPC
Disadvantages
Development of venous collaterals from SVC
to IVC
–
–
–
–
Pulmonary AV fistula
Abnormalities in regional pulmonary perfusion
Decreased angiogenesis of PA due to nonpulsatile flow
Lower oxygen saturation in older children
• Optimal operation time
– 6m ~ 1 yr age
Pre-Fontan Palliation
Hemi-Fontan operation
• BCPS , with patch occlusion
of the SVC & RA junction
• Similar hemodynamics to BCPS
• Easy conversion to later Fontan op.
• More suture line than BCPS
late arrhythmia
Pre-Fontan Palliation
 Total Cavopulmonary Shunt
(TCPS)
• Kawashima. 1978
• LA isomerism,
Exclusion of hepatic vein
Bidirectional Glenn Procedure
Advantages
• Advantages of the staged approach for the Fontan-type
operations are giving effective pulmonary blood flow
and stepwise adaptation of ventricular geometry to the
reduction in volume load
• The bidirectional Glenn procedure with additional
pulmonary blood flow may provide patients with
higher oxygen saturation and more growth of
pulmonary arteries than BDG without APF.
• However, there are disadvantages to BDG with APF,
such as the elevation of venous pressure and volume
overload on the ventricle
Bidirectional Glenn Procedure
Additional pulmonary blood flow
• Antegrade pulmonary blood flow to be controlled and
APF should be reduced at BDG.
• CVP of 16 mm Hg or less might be ideal at the
operating theater as it is well known from our
experience that CVP decreases 2 to 3 mm Hg by
extubation after BDG.
• For banding the pulmonary trunk, an expanded
polytetrafluoroethylene tube, 3 mm in width, was used.
• For banding the BT shunt, an ePTFE graft of 8 mm
length and same with the shunt or smaller in size was
used to wrap the previously created BT shunt.
Fontan Operation
 Surgical options
I. Atriopulmonary Connection
II. Atrioventricular Connection
III. Total Cavopulmonary Connection ( Lateral
Tunnel )
IV. Fenestrated or Adjustable Fontan Operation
V. Fontan with Unidirectional Cavopulmonary
Connection
VI. Extracardiac Total Cavopulmonary Connection
Atriopulmonary Connection (I)
Fontan & Baudet.
1971
 Physiologic correction
– Classic Glenn shunt
– RA-LPA with aortic valve
homograft
– Closure of ASD
– Pulmonic valve homograft
– MPA ligation
Atriopulmonary Connection (II)
Kreutzer et al. 1973
– Anterior atriopulmonary
connection
– Direct RAA to MPA
– Pulmonic valve preserved
– No valve in IVC
• Ross & Somerville, Stanford et
al. 1973 / Miller et al. 1974
– RAA to MPA using Homograft
Atriopulmonary Connection (III)
Doty et al. 1981
– Direct & posterior
atriopulmonary connections
– Less susceptible sternal
compression
– Wide applications
Atriopulmonary Connection
General approach
• Methods
– Location : anterior / posterior
– Connection : direct / valved conduit
– Separation of flow : simple ASD closure / atrial partitioning
• Advantages
– Simple, reproducible, wide applications
• Disadvantages
– More turbulent, atrial hypertension
Atriopulmonary Connection
Considerations
• Use of valve ? : not helpful
• RA contraction
– Not essential to maintain C.O
– Turbulence
energy loss
• Exposure of RA to high CVP
• RA dilatation & hypertrophy
– Supraventricular arrhythmia
– Venous congestion
–
Need separation of RA to pathway
of systemic venous return : Conversion
to TCPC
Atrioventricular Connection (1)
Bowmann et al.
1978
– Atrioventricular
connection,
– Porcine valved conduit
Atrioventricular Connection (II)
Bjork et al. 1979
– Atrioventricular connection,
– Atrial tissue flap &
pericardial roof
– Prevent conduit associated
obstruction
• Atrioventricular connection
– No advantage
Total Cavopulmonary Connection
Lateral Tunnel
 De Leval et al. 1988
• Atrial partitioning with PTFE or Dacron tube graft
• Creating a nearly straight pathway
: laminar flow without turbulence & energy loss
Total Cavopulmonary Connection
Lateral Tunnel
Advantages
– Favorable flow patterns within systemic venous pathway with
reduced risk of atrial thrombosis
– Reproducibility irrespective of atrial & AV valve morphology
– Reduction of risk of early & late arrhythmia
– Low risk of surgical damage of sinus node artery
Disadvantages
– Possible injury from myocardial ischemia during ACC
– Baffle obstruction of the pulmonary veins or AV valves
– Baffle leaks cause cyanosis and failure of palliation
– Dysrhythmia from atriotomy & extensive intraatrial suture lines
Fenestrated or adjustable Fontan
Rationale
• Reduce systemic venous hypertension
– Decreased morbidity & mortality by reducing
: Chronic LCO, pleural effusion, ascites,
hepatic congestion, protein-losing
enteropathy
by creating a shunt
• Maintain preload & C.O.
• Adding preload
regression of ventricular hypertrophy
• Decreased O2 saturation compensated by C.O.
Fenestrated or Adjustable Fontan
Baffle Fenestration
Snare-Controlled Adjustable ASD
• Bridges et al. 1990
• Shunt amount : size & PVR
• Laks et al. 1988
Unidirectional Cavopulmonary Connection
History
• Lins et al. 1982
• Delenon et al. 1993
• Laks et al. 1995
–
–
–
unidirectional CP connection
SVC to LPA, IVC to RPA
: ideal pulmonary blood flow distribution
Obligatory source of pulmonary blood flow
: obtain acceptable arterial saturation
Selective decompression of IVC
Unidirectional Cavopulmonary Connection
Baffle Fenestration
Adjustable ASD
Extracardiac Cavopulmonary Connection
Rationale
• Lateral tunnel Fontan operation ± fenestration
– marked improvement in survival
– several drawbacks previously mentioned
Avoid complications due to intraatrial lateral tunnel op.
Preserve hemodynamic effects of intraatrial lateral
tunnel op.
Result in Extracadiac TCPC
Extracardiac Cavopulmonary Connection
Extracardiac Conduit (1)
• Giannico et al. 1990
• Gore-Tex tube graft
Extracardiac Cavopulmonary Connection
Extracardiac Conduit (2)
• Concomitant PA enlargement
with conduit patch
• Shunt formation
– between extracardiac conduit & RA
– with Gore-Tex tube graft 4 or 5mm
Extracardiac Fontan Operation
Clipped tube fenestration
surgical clips
Extracardiac Cavopulmonary Connection
Extracardiac Epicardial Lateral Tunnel (EELT)
• Lashinger et al. 1992
• Gore-Tex patch or pericardium
Extracardiac Pericardial Fontan
Operative techniques
The pericardial pedicle is fashioned and the anterior wall of the right atrium is
sutured to the backwall of the ipsilateral pericardial flap.
The completed EPPF. (EPPF = extracardiac pedicled pericardial Fontan; IVC =
inferior vena cava; LPA = left pulmonary artery; RPA = right pulmonary artery; SVC
= superior vena cava.)
Pedicled Pericardial Conduit
Operative techniques
Large rectangular flap of pericardium was cut, leaving it pedicled
so as to preserve its vascular connections, and the flap was then rolled
into a tube shape. B, Conduit with the aid of a temporary bypass from
inferior vena cava (IVC) to the atrium.
Extracardiac Cavopulmonary Connection
Considerations
• Advantages
– Closed no touch technique
avoidance of ischemic arrest
: helpful in patients with ventricular diastolic dysfunction
– Maintain more favorable laminar flow
– Reduce early and late atrial dysrhythmia , atrial thrombosis
: RA wall stress , avoidance of atriotomy & atrial sutures
– Technically simple in systemic or pulmonary venous anomalies
• Disadvantages
– Anticoagulation
– Technical difficulty in applying large conduit size
Arrhythmia in Fontan Operation
Surgical options
• Kao et al. 1994
– Conversion of atriopulmonary to cavopulmonary
connection in the management of Af
• Gandhi et al. 1996
– In an acute canine model
– In the absence of hemodynamic alteration
– Fontan suture lines alone permit the induction of AFL
Arrhythmia in Fontan Operation
 Surgical options
• Mavroudis et al. 1998 / Deal et al. 1999
• Conversion to TCPC
+ Arrhythmia circuit cryoablation
+ Antitachycardia pacemaker
• 3 identified major tachycardia circuits
1) area between coronary sinus & IVC
2) lateral atriotomy
3) superior rim of the prior ASD patch
3
• Prophylatic cryoablation
In first time Fontan reconstructions : intriguing issue
2 1
TCPC Geometry
Optimization
• Energy conservation
– Very important to circulation
• Flow separation of caval inlets
to conserve energy (in vitro)
Offset : de Leval et al. 1996
Flaring & offset : Ensley et al. 1999
Curvature : Sharma et al. 1996
Gerdes et al. 1999
Needs a further investigation
& clinical application
SVC
Caval offset
RPA
LPA
IVC
Fontan Operation
Postoperative management
• Reduce pulmonary vascular resistance
• Maintain adequate preload
• Consider other surgical options
when untolerable to Fontan physiology
• Treatment of complications
Fontan Operation
Risk factors for death
•
•
•
•
•
•
•
•
•
Acute ventricular decompression
Late pulmonary & ventricular deterioration
Younger age & older age at operation
Cardiac morphology
Small central right & left pulmonary arteries
Increased mean PAP and PVR
Advanced chamber ventricular hypertrophy
Atrial isomerism
Right atrial connection to pulmonary artery
Fontan Operation
Complications
•
•
•
•
•
Arrhythmia
Thromboembolism
Effusion : pleural, pericardial, chylothorax
Protein-losing enteropathy
Fistulas
– intrahepatic venous fistula
– pulmonary AV malformation
– systemic venous collaterals
• Fontan take-down
• Acute liver dysfunction
Persistent Pleural Effusions
Risk factors after Fontan
• Persistent pleural effusions are the most troublesome
complication in the early postoperative period and this
problem to occur in 13% to 39% of patients after
surgical intervention.
• The risk factors that contribute to persistent pleural
effusions after the extracardiac Fontan procedure have
not been well established.
• Lower preoperative oxygen saturation, presence of
postoperative infection, smaller conduit size, and longer
duration of cardiopulmonary bypass were associated
with persistent pleural effusions after the extracardiac
Fontan procedure.
Persistent Pleural Effusions
Contribution to development
• Inflammatory response results mainly from exposure
to CPB, causing increased capillary leakage and
subsequent fluid retention.
• Increased hydrostatic pressure in Fontan circulation
results from factors increasing the pulmonary vascular
resistance.
Lack of atrioventricular synchrony also contributes to
this mechanism.
• Hormonal mechanism involves activation of the reninangiotensin system, and more recent evidence suggests
involvement of atrial natriuretic peptide & vasopressin.
Fontan Operation
Management of complications
• Supraventricular arrhythmias after extracardiac
Fontan operation are probably multifactorial and
mandate continuous surveillance.
• Patients with systemic ventricular dysfunction,
bilateral superior venae cavae, and heterotaxy
syndrome and those undergoing completion Fontan
may exhibit a high incidence of these arrhythmias.
• The viable extracardiac Fontan may be the operation of
choice in a selected subset of patients.
• Serial dynamic radionuclide studies may be useful for
evaluation of anatomic and functional flaws of the
Fontan circuit
Pulmonary A-V Malformations
Nature
• Pulmonary arteriovenous malformations develop
embryologically owing to incomplete development of
the pulmonary capillary system and are characterized
by greatly increased numbers of nonessential
pulmonary blood vessels that do not serve a critical gas
exchange function but cause arteriovenous shunting.
• The existence of PAVMs in normal lungs has been
verified and under certain physiologic conditions these
vascular channels may become dilated and more
numerous.
• PAVMs are also a feature of the hepatopulmonary
syndrome that can occur in patients with hepatic
cirrhosis, and of hereditary hemorrhagic telangiectasia
Pulmonary A-V Malformations
Development
• An absence of a "hepatic factor" or "mesenteric
factor" and that an unidentified element in the hepatic
venous drainage inhibited the recruitment and
dilatation of preexisting pulmonary arteriovenous
connections
• Angiogenic process, as well as recruitment of
preexisting channels that dilated when there was an
absence of hepatic venous return to the pulmonary
circulation
• Alternately hypothesized that the liver may be
responsible for the degradation of an angiogenic
substance which is not removed after BCPA.
Pulmonary AV Malformations
Diagnostic criteria
• Rapid pulmonary AV transit (< 3 heart beats)
of contrast on proximal PA angiography
• Typical reticular or spongy pattern in the
peripheral pulmonary vasculature on PA
angiography
• PV desaturation ( 92%) in angiographically
affected lung segments.
Pulmonary A-V Malformations
Risk factors
• The PAVMs appear within weeks of BCPA or the
Kawashima operation and can be demonstrated earliest
by contrast echocardiography.
• Bilateral SVCs and an interval of more than 2 years
were independent risk factors for the development of
PAVMs after the Kawashima operation
• Unilateral streaming of HV-PA flow is an important
concern after HV inclusion in patients with heterotaxy
and azygous continuation of the IVC
Pulmonary A-V Malformations
Management inferences
• Development of PAVMs is facilitated by exclusion from
the pulmonary circulation of a substance produced or
metabolized in the liver
• Resolution of PAVMs after CPA requires delivery of
hepatic venous blood, and the putative hepatic factor, to
the affected lung
• Putative hepatic factor either has a short circulating
half-life or is eliminated/inactivated during passage
through a systemic or pulmonary capillary bed
Approaches to Single Ventricle
Single Ventricle Surgery
Aims of treatment
How do we achieve
1. The highest success rate
2. The highest long-term survival rate
3. The best quality of life
Fontan Operation
Pulmonary flow pattern
• 63% of systemic venous flow during inspiration
• Negative intrathoracic pressure is a principal draining
force
• Gravity plays a role in SVC flow to the pulmonary
arteries.
• Hemidiaphragmatic paralysis decrease pulmonary
function by approximately 25%, but stability of adult
rib cage & strength of accessory muscles of respiration
help to compensate for decreased diaphragmatic
function.
Fontan Operation
Changes of systemic venous return
• Lack of a right-sided pump increase afterload.
• In series may add additional resistance to
systemic venous return.
• At risk for transient ventricular dysfunction for
a systemic venous return
Fontan Procedure
 Identification
•
•
•
•
•
Reurrent obstruction in aortic arch
Prognosis or new development of
subaortic stenosis
Distortion of the pulmonary arteries
Deterioration of ventricular, or
atrioventricular valve function
Development of elevated pulmonary
vascular resistance
Fontan Procedure
 AV valve regurgitation
1. Incidence ; 6% (5-40%)
2. Natural factors
Amount of pulmonary flow & length of time with ventricular
volume loaded
3. Mechanism
* Functional ; central jet, improve after BCPC
* Structural ; dysplastic, cleft, prolapse, restricted,
frequent in common AV valve,
rarely improve after BCPC
4. Solution
* Small shunt before BCPC
* Early BCPC in young (reduction volume load by 33% after
BCPC)
Common AV Valve Repair
• Regurgitation through central position of AV valve was repaired
by supporting central portion of common AV valve by closure of
cleft and suture of adjacent central portion of leaflets
Fontan Operation
Minimal age
 When children begin walking, standing, creeping,
active extremity movement, around 8 months old
or body weight more than 10 kg
 Single-ventricle patients can transition towards
Fontan completion as early as 1 year of age
• Advantages
* Preservation of ventricular function through relief of chronic
volume load and hypoxemia
* Protection of pulmonary vasculature by removing shunt
• Disadvantages
* Small anatomical structure
* More reactive pulmonary vascular bed after CPB
Cyanotic Heart Diseases
 Advantage of early repair
1. Avoid the hazards of prolonged cyanosis on
ventricular function & neurologic development
2. Prevent the effects of chronic ventricular
volume overload
3. Reduce the risk of cerebrovascular embolism
and brain abscess
Early Fontan Repair
Advantages
o It appears that a period of approximately 6 months
aftersuperior cavopulmonary connection is sufficient in
most cases for the appropriate changes in ventricular
geometry and diastolic properties of the single ventricle
to occur for a successful Fontan circulation
1. Avoid multiple palliative surgery
2. Avoid chronic ventricular volume overload
3. Avoid chronic hypoxia
4. Prevent late ventricular failure and possible
arrhythmia
Fontan Operation
Staging procedures
• This policy involves the use of small shunt to provide limited
pulmonary blood flow, construction of an early bidirectional
cavopulmonary anastomosis, early identification and correction of
systemic ventricular outflow obstruction, & avoidance of prolonged
periods of PA banding.
• But it remains unclear whether all children should undergo an
intermediate bidirectioal Glenn shunt procedure prior to Fontan., the
optimal timing of a bidirectional Glenn shunt, except in patients with
complex anatomy excessively cyanosed by 4-6 months.
• Pprimary establishment of Fontan circulation if the patient has good
conditions of the Fontan circulation, otherwise we will proceed to a
bidirectional Glenn procedure, probably at the age of 6 months.
Fontan Operation
Staging toward completion
1. Palliative procedures before 6 months of age
1) Palliative shunt procedure
2) PAB
3) Norwood operation
4) Palliative arterial switch operation
5) BCPS
2. Palliative procedures after 6monhs of age
1) BCPS
2) Hemi-Fontan operation
3) BCPS with DKS or with arterial switch operation or
with subaortic or VSD resection
4) Total cavopulmonary shunt (Kawashima)
Fontan Operation
Aims of palliation
1. Maintain normal pulmonary compliance
1) PA pressure
2) PVR
3) PA shape & size
4) PVOD
2. Maintain normal cardiac compliance
1) Cardiac volume load
2) Cardiac pressure load
3) Cardiac muscle hypertrophy
4) Endomyocardial ischemia
Partial Fontan Operation
 Hemodynamic interest
* Due to persistence of right-to-left shunt
1) Decreases pulmonary artery pressure
2) Preserves the cardiac output
3) Unloads the univentricular hearts
Fontan Operation
Left Superior Vena Cava
• Persistent left SVC arises from a faulty embryogenesis
between the fifth and eighth week and affects
approximately 0.3% of the population
• Its prevalence increases to 2% to 4.5% in patients with
other congenital heart defects.
• The addition of that third inflow introduces
supplementary parameters and issues into the quest for
an optimal total cavopulmonary connection (TCPC)
design and has not yet been investigated.
Incomplete Atrial Partitioning
 Reasons of deliberation
1. Temporary pulmonary vascular or pulmonary
dysfunction related to damaging effects of
cardiopulmonary bypass
2. Temporary myocardial dysfunction related to
inadequate myocardial management
1) Increased ventricular wall thickness and
myocardial edema
2) Decreased ventricular compliance and volume
3. Expect to regress these responses over several
weeks or months thereafter
Partial Fontan Circulations
 Advantages of IVC-PA shunt
1. Fixed Qp/Qs not dependent on the transatrial
gradients as for the fenestrated Fontan
operation
2. Acceptable level of arterial oxygen saturation
3. Mainly an increased facility to perform the
second step of the Fontan operation
Partial Fontan Circulations
IVC-PA shunt
1. Higher transpulmonary blood flow
2. Promote additional growth of the pulmonary artery
3. Oxygen delivery remains at a low level.
4. Exercise of the lower limb increases the flow of IVC.
5. Technical and hemodynamic ease of the second operative step
6. Avoiding the development of arteriovenous fistula in the lungs
(hepatic factor)
7. No risk of collateralization between IVC and hepatic veins
8. Pleural effusions were minimal, although IVC pressure is slightly
increased, due to low pressure in SVC and absence of thoracic duct
drainage obstruction.
Single Ventricle Palliation
Mitigating factors in Down syndrome
1. Abnormalities of lung development
2. Pulmonary immunocompetence
3. Hypnotic and hyperventilation
4. Upper-airway obstruction with a propensity
for nighttime hypercarbia, hypoxia and
subsequent vasoconstriction
Hemi-Fontan Operation
Hemi-Fontan Operation
Alternative Method
Bidirectional Cavopulmonary Connection
SVC
Fontan Operation
Risk Factors
• Elevated pulmonary artery pressure
• Elevated pulmonary vascular resistance
• Ventricular dysfunction
• Systemic AV valve regurgitation
• Longer cardiopulmonary bypass
• Significant pulmonary artery distortion
• Systemic-pulmonary artery collaterals
Fontan Operation
Major risk factors
1. Pulmonary artery distortion
2. Elevated pulmonary arteriolar resistance
(>2 Wood units)
3. Elevated pulmonary artery pressure (>15mmHg)
4. Presence of either left AV valve atresia or a
common AV valve
5. Ventricular dysfunction (LVEDP >15mmHg)
6. Young age (< 3years)
AP Fontan Operation
Hemodynamic charateristics
1. Fluid losses associated with flow expansion
from the vena cavae into the RA chamber
2. Collision and mixing of vena cava flows
3. Flow contraction from the distended RA
into the main pulmonary artery
Lateral Tunnel Procedure
 Advantages
1. Technically simple and reproducible in any
atrioventricular arrangement
2. Maintenance of low pressure is possible in most of
the right atrium and coronary sinus with possible
improvement of atrial arrhythmias
3. A reproduction of energy loss as a result of lessened
turbulence in the LT would decreases the cardiac
index.
Extracardiac Conduit Fontan
•
Unfavorable & Favorable
Malposition of heart
Redo operation
Small heart size
Old age
Venous malformation
No intracardiac procedure
Bilateral SVC
Decreased heart function
Hepatic vein anomalies
Pulmonary venous anomalies
IVC interruption
Good pulmonary artery size
Coagulopathy
Extracardiac Fontan Procedure
(Extracardiac lateral tunnel & Extracardiac lateral conduit)
 Advantages
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Avoidance of aortic cross clamping
Hemodynamic benefits of total cavopulmonary connection
Avoidance of atriotomy and intraatrial suture line
Preservation of sinus rhythm and no or low arrhythmia
Drainage of the coronary sinus to low pressure atrium
Allowance for early or late fenestrations
Prevention of early and late baffle leaks
Prevention of obstruction of pulmonary veins or AV valves
Allowance for growth in lateral tunnel procedure
Reduce the risk of systemic emboli
Fontan Operation
Criteria of fenestration
•
•
•
•
•
•
•
Elevated pulmonary artery pressure
Elevated pulmonary vascular resistance
Abnormal pulmonary artery anatomy
Systemic right ventricle
Impaired ventricular function
Significant AV valve regurgitation
Younger age
Fontan Operation
Results of fenestration
• Spontaneous closure
* 2.5-4 mm : 1 year closure 50-90%
* > 4 mm
: 1 year closure 40-70%
• Risks
* Thromboembolism
* Prolonged desaturation
* No thromboembolism less than 2.5mm
TCPC Geometry
General principle
• In in vitro model, with no offset between the vena cava,
hepatic blood distribution and concentration to each lung
was similar to normal but energy loss involved is
relatively high due to mixing of two vena cava flow.
• This resistance to blood flow is mainly due to the
geometry of the connection with bends,expansions and
junctions all creating energy losses through increased
friction and flow disturbance or mixing.
• In general the greater the disruption to the flow, the
greater the fluid energy loss
TCPC Geometry
Flow structures
• In geometries with a single SVC, offsetting the IVC and
SVC by 1.0 to 1.5 caval diameter minimizes the flow
disturbances caused by the colliding inflows
• Similarly, with dual SVCs, setting the IVC in between
the 2 SVCs results in an offset between the IVC and
each one of the SVCs, which in turn decreases flow
instabilities, such as those observed in the original
anatomy distal to the RPA
• Suturing the LSVC closer to the RSVC in the hemiFontan or Glenn stage may be a better way to decrease
the distance by which the IVC should be shifted in the
final TCPC stage
TCPC Geometry
Toward surgical planning
• It is important to keep in mind some possible
TCPC design improvements.
• Shifting the IVC in between the 2 SVCs seemed
to be a feasible and efficient way to obtain a
better repartition of the hepatic flow to lungs.
• In extracardiac cases, for example, shifting the
IVC toward the LSVC may compress the
pulmonary veins and worsen the patient's
outcome rather than improving it.
Fontan Palliation
Three-dimensional grids
Fontan Operation
Morphometry
• FA ; Fontan area
• SVA ; Systemic venous area
Lateral Tunnel Fontan
Extracardiac Fontan Operation
• Total cavopulmonary
connection with
dextrocardia
• Intra-extraatrial lateral
tunnel technique
Extracardiac Fontan Operation
• Extracardiac Fontan
operation without CPB
and temporary atria to
IVC shunt
Extracardiac Fontan Operation
• Extracardiac Fontan
operation without CPB
and temporary systemic
arterial to pulmonary
artery shunt
Extracardiac Fontan Operation
• Diagram shows
completion of
distal anastomosis
without CPB
Fontan Operation
Postoperative care
1. Reduce the systemic vascular resistance
Elevation of the venous pressure results in a reflex
rise in the tone of the arterioles
2. Minimize the pulmonary vascular resistance
 Pulmonary vascular resistance is minimized when the
lung is operating near functional residual capacity
3. Takedown the Fontan procedure to BCPC who cannot
tolerate the Fontan physiology
4. Development of pleural or pericardial effusion
 Young age and hepatic capillary bed is the leakiest
of the systemic capillary beds.
Fontan Operation
Right atrial pressure
• RA pressure of 16 mmHg or less with maintaining cardiac
output is ideal and they generally convalesce well.
• Severe arterial desaturation in fenestrated Fontan may be the
warning sign rather than elevation of RA pressure.
• When LA pressure is elevated to within a few mmHg of RA
pressure, ventricular dysfunction or AV valve dysfunction are
etiologic.
• When RA pressure remains 5mmHg, or higher than LA pressure,
pulmonary vascular disease or pulmonary arteriolar spasm or
small size of pulmonary artery may be responsible.
• When RA pressure is high, but PA pressure and LA pressure are
not, then an obstruction exists.
Fontan Operation
Takedown
1. Usually within 12 hours after after operation
2. Poor hemodynamic state, and presence of an elevated
RA and PA pressure with a LA pressure 5 mmHg
or more lower than the right
3. Conversion to a hemi-Fontan procedure in case of
cavopulmonary connection
4. In other form of modified Fontan operation, removal
of the patch alone results in severe and fatal
arterial desaturation, thus usually the entire
procedure must be taken down with bidirectional
cavopulmonary shunt.
Fontan Operation
Chylothorax
• Injury of the thoracic duct during surgery
• Disruption of lymphatics during thymus gland removal
• The leaking micropores gradually enlarge with time
and with passage of macromolecules through them,
so that chylomicron can pass.
• Adequate drainage and high caloric intake are the
mainstays of treatment.
• Ligation of the thoracic duct rarely is useful.
Single Lung Fontan Operation
Strategies
• The success of the Fontan procedure in selected cases of
single-lung physiology is likely related to the functional
and anatomic compensation by the remaining lung.
• Pulmonary vascular resistance decreases significantly in
the remaining lung postpneumonectomy over time (2 to
12 months) with an increase in maximal cardiac output .
• Dgree of pulmonary compensation postpneumonectomy
is greater in young than in adults, suggests a relationship
between developmental and adaptive potentials
• Fontan operation in patients with a single lung requires
careful preoperative assessment and must be done to
determine whether these patients are acceptable surgical
candidates.
Fontan Procedure
Coagulation factor abnormalities
1. Protein C deficiency
Natural anticoagulant synthesized in the liver as a Vit-K dependent
protein, after activation by thrombin, protein C is a potent inhibitor
of coagulation cascade and stimulate fibrinolysis.
2. Protein S deficiency
Protein S acts as a cofactor in this pathway, and it futher stimulate
fibrinolysis.
3. Factor Vll
A coagulation factor and is part of the extrinsic pathway.
Factor Vll interacting with tissue factor activates the extrinsic pathway.
A low level can support the tissue factor-induced coagulation in
pathologic state.
Fontan Operation
 Thromboembolism
#
Virchow’s triad
1) stasis
2) presence of abnormal surface
3) change in coagulation
1. Hemodynamic factor
Stasis and area of sluggish flow by
1) low cardiac output
2) less pulsatile pulmonary circulation
2.
Coagulation abnormality
1) Protein C
2) Protein S
3) Factor VII
3.
Use of prosthesis, sutures, intimal change
Fontan Operation
Reasons of desaturation
• Early late systemic desaturation can occur from
various systemic venous channels connecting to
the pulmonary veins, coronary sinus, or left-sided
atrial structures that may become manifest
immediately or develop over time
• Distinguish these entities from lung diseases or
intrapulmonary arteriovenous malformation and
specific morphology of venous connection
• Surgical or interventional closure is indicated
Pulmonary A-V Malformations
Natures
• Pulmonary arteriovenous malformations, pathologically,
dilated capillary and precapillary vessels with evidence of direct
arteriovenous communication are seen.
• They may be hereditary as in Rendu-Osler-Weber syndrome, or
acquired as in hepatopulmonary syndrome, or in complex
congenital heart defects with single ventricle physiology palliated
by superior cavopulmonary connections.
• “Hepatic factor" is critical in preserving the integrity of
pulmonary vasculature in normal subjects.
• This hepatic factor could be related to regulators of nitric oxide,
the polypeptide super family transforming growth factor and its
antagonists; the absence of the latter would produce an unopposed
pulmonary vasodilatation leading to PAVMs.
Arrhythmias after Fontan Op.
1. Incidence
1) Early : 12~48%
2) Late : 50% more over 10~15 years
3) 5-30% after 5 years of TCPC
2. Mechanism
1) Early
a. Automatic atrial tachycardia and flutter
acute elevation of atrial pressure
recent surgical procedure
b. Junctional ectopic tachycardia
myocardial dysfunction
c. Heart block
2) Late
a. Extensive atrial surgery
b. Destruction of conduction tissue
c. Disruption of SA node artery
d. Direct damage to sinus node
e. Increased atrial pressure
f. Poor ventricular function
Arrhythmia in Fontan Operation
Atrial tachycardia
1) Early
Atrial flutter
Atrial ectopic tachycardia
AV reentrant tachycardia
2) Late
Atrial flutter (5~30% at 5-year follow-up)
AV reentrant tachycardia
Atrial ectopic tachycardia
Failure of Fontan Circulation
Consequences
• Right atrial dilation, inefficient flow dynamics,
baffle thrombus, repeated subclinical
pulmonary emboli, and atrial arrhythmias, can
coalesce to cause the Fontan circulation to fail
• Loss of atrioventricular coordination & efficient
ventricular preloading from atrial arrhythmias,
combined with decrease myocardial perfusion
from coronary sinus hypertension, eventually
leads to systemic ventricular dilation & failure
Adult Functional Single Ventricle
Characteristics
• As having a "failed" Fontan (chronic
arrhythmias, protein losing enteropathy,
pleural effusions, ventricular dysfunction,
limited exercise capacity)
• After long-term surgical palliation
• As uncorrected.
Fontan Conversion
Indications for conversion
• Interrelated combination of increasing
symptoms of heart failure,
• Systemic ventricular failure,
• Elements of anatomic obstruction
• Reefractory arrhythmias.