Transcript Methods of Homograft Viability Test

Tetralogy of Fallot
Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery
Tetralogy of Fallot
1. Definition
Tetralogy of Fallot is characterized by underdevelopment of right
ventricular infundibulum with anterior & leftward displacement
(malalignment) of infundibular(conal, outlet) septum & it’s parietal
extension. This displacement of septum is associated with right
ventricular outflow stenosis & ventricular septal defect.
2. History
Stensen
:
Fallot
:
Blalock & Taussig :
Sellors & Brock :
Lillehei & Varco :
Mayo group
:
Kirklin
:
1st description in 1672
Known tetralogy in 1888
1st surgical intervention in 1945
Closed valvotomy & infundibulectomy in 1948
1st repair by cross circulation in 1954
1st repair by pump oxygenator in 1955
Conduit use for TOF+PA in 1966
Tetralogy of Fallot
Pathophysiology
• Tetralogy of Fallot consists of a large VSD,
RVOTO, aorta overriding the VSD, and right
ventricular hypertrophy.
• RVOTO leads to right-to-left shunting across a
nonrestrictive VSD, resulting in adequate
pulmonary blood flow and varying degrees of
cyanosis.
• It comprises 10% of CHD & the most common
among the cyanotic defect(50%)
Pulmonary Infundibulum
Role & its function
• The outlet portion of the right ventricle had not only
a passive role in right ventricular contraction, and
the peristaltic mode may be crucial to achieving a
complete emptying of the right ventricular cavity.
• The delayed opening of pulmonary valve might be
more suitably explained by the peristaltic mode of
function of right ventricle than by its intrinsic power
• The pulmonary infundibulum ejecting the blood that
it had accumulated at a time when the rest of the right
ventricle was already relaxing.
Ventricular Interaction
RV & LV interaction -Cross-talk• While the deeper layer of myocardial fibers are
separated, there are shared superficial fibers
that encircle the normal LV and RV.
• Furthermore, in some forms of CHD, such as
TOF, the deeper layers of RV and LV may be
contiguous within the interventricular septum.
• The function of the two ventricles is therefore
linked, in both the structurally normal and
abnormal heart.
Tetralogy of Fallot
Surgical morphology
1. Right ventricular outflow tract
. Infundibulum, pulmonary valve, ring
2. Pulmonary artery
. Trunk, bifurcation, distal PA, iatrogenic problem,
collateral blood flow
3. VSD & conduction system
4. Aorta, aortic arch & ductus arteriosus
5. Right & left ventricle
6. Coronary arteries
7. Major associated cardiac anomalies
PDA, multiple VSD, A-V canal, ASD, AR
Tetralogy of Fallot
Surgical anatomy
TOF
Aorta
VSD
VSD
PA
Tetralogy of Fallot
Genetic syndromes & outcome
• Approximately 10% to 15% of TOF patients carry a
22q11 deletion (del22q11) and that 7% of TOF have
trisomy 21
• Teralogy of Fallot patients with Alagille syndrome
carry a mutation in JAG1 (jagged1 gene) and
VACTERL, CHARGE, or other syndromes can be
associated with TOF
• Patients with TOF and an associated genetic defect may
face additional risk for primary repair; for example, if
there is the need of extracardiac surgery for associated
anomalies or because of immunodeficiency or altered
compliance of the pulmonary vasculature.
Tetralogy of Fallot
Clinical features & diagnosis
1. Clinical presentation
Cyanosis
; varies with severity of PS
CHF ; 10 % of patients in 2-3 months, and gradual increase in cyanosis
2. Physical examination
Cyanosis of variable degree & clubbing, systolic ejection murmur
3. Laboratory studies
Polycythemia , platelet depression, prolonged coagulation
4. Chest radiography & electrocardiography
5. Echocardiography, CT angio, MRI
6. Cardiac catheterization & angiocardiography
Tetralogy of Fallot
Natural history
1. Incidence
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: One of the most common CHD
3~6/10000 births (5%~10% of CHD)
Symptoms & survival : 25% death in 1 yr
40% death in 3 yrs
70% death in 7 yrs
95% death in 40 yrs
Hypoxic spell
: Hyperactivity of infundibulum
in the 1st year of life & sudden
reduction of SVR
Pulmonary artery thrombosis ; in severely polycythemia
Pulmonary vascular disease ; rarely
Genetic history ; more likely ( x 15 )
Tetralogy of Fallot
 Operative indications
Diagnosis is generally an indication for repair.
1. When asymptomatic & uncomplicated, repair is
deferred until 3 to 24 months of age.
2. Initial shunting operation for symptomatic patient
less than about 6 months of age, & definitive
repair some time between 6 & 24 months of age.
3. Early primary repair when the infant is importantly
symptomatic in the first 3 months.
4. Early repair is advisable, particularly in the first
year of life
Tetralogy of Fallot
Aim of repair
• First, the procedure must relieve the right ventricular
hypertension ( PS ) by mobilizing, transecting, and
infrequently, resecting parietal and septal extensions
(bands) of the crista supraventricularis.
• The aim of infundibular dissection is to increase the
circumference of the infundibulum by enlarging each
lateral recess in front of the conal septum
• Second, the VSD must be closed completely while
avoiding the conduction system
• When the first criterion is met by a right atrial approach,
it is considered the method of choice.
Tetralogy of Fallot
Operative techniques
1. Evaluation
. Shunting vs one-stage repair
. Z-valve of pulmonary annulus
2. Surgical approach
. Provide excellent exposure
. Avoid damage to coronary artery
. Avoid excessive muscle division in RV
3. Details of repair
. Transventricular repair
. Transatrial & transpulmonary repair
Tetralogy of Fallot
Systemic-pulmonary shunts
• Various positions of the usual systemic-pulmonary
arterial shunts for augmenting pulmonary blood flow
Systemic-Pulmonary Shunts
 Via median sternotomy
Tetralogy of Fallot
Anatomy
• Anatomic substrate of repair from right ventricular approach
Tetralogy of Fallot
Anatomy
• Anatomic substrate of repair from right atrial approach
RVOT Reconstruction
Principles
• The diameter of annulus with a Hegar dilator that
passes snugly but not tightly through it.
• Generally, a transannular patch should not be placed
when Z value is larger than -3.
• When a polyester tube is used, one is selected whose
diameter corresponds to a Z value of 0 to +2.
• The patch when properly trimmed, its convexity is
ensured in all direction, as is a relatively square cut of
its distal end.
• To widen the LPA stenosis, a rectangular piece of
pericardium is cut about one and a half times wider
than the apparent diameter of the LPA and about one
and a half times longer than the incision in the LPA.
RVOT Reconstruction
Application of monocusp patch
• Transannular patching is often necessary for
reconstruction of right ventricular outflow tract
obstruction, but it leads to transvalvular regurgitation.
• Acute pulmonary valve regurgitation of higher degrees
impairs right ventricular function, and seems to be
associated with increased perioperative mortality.
• Regurgitation fraction after reconstruction is dependent
on the length of the monocusp patch relative to the
length of the hypoplastic pulmonary root.
• The best result was obtained with a monocusp patch
roughly two times as wide as the hypoplastic pulmonary
root
RVOT Patch Widening
Principles
• The width of the patch across the pulmonary annulus
must be generous enough to eliminate most of the
gradient.
• It is better to accept a mild to moderate gradient than
to create wide open pulmonic insufficiency.
• The new annulus diameter should not be much greater
than the Z-zero pulmonary annular size for the patient.
• The toe of the patch must be oval or square to minimize
the risk of subsequent anastomotic stenosis
Tetralogy of Fallot
Surgical repair
Tetralogy of Fallot
Operative technique
• The rectangular patch when properly trimmed, its convexity is
ensured in all direction, as relatively “square cut” of its distal end.
Tetralogy of Fallot
Patch enlargement
•
Extension of a pulmonary arteriotomy onto the left
pulmonary artery and correct patch configuration
Tetralogy of Fallot
RVOT reconstruction(1)
• Monocuspid valve
Tetralogy of Fallot
RVOT reconstruction(2)
• Monocuspid valve may be attached to the pericardial roofing patch.
The cusp diameter is fashioned somewhat larger than the planned
roofed RV outflow.
Tetralogy of Fallot
RVOT reconstruction(3)
• It is cut more or less circular and sutured to the patch when
the latter suturing from distally reaches the valve annulus.
Tetralogy of Fallot
Pulmonary valve saving
Tetralogy of Fallot
Pulmonary valve saving
Tetralogy of Fallot
Pulmonary valve-sparing
(A) Pulmonary arteriotomy. (B) Autologous pantaloon pericardial patch.
(C) Completed pulmonary artery pantaloon patch.
Tetralogy of Fallot
Postoperative care
• Patients have a tendency to increase their interstitial,
pleural, & peritoneal fluids early postoperatively.
• The hemodynamic state is assessed continuously and
management constantly reviewed.
• Care lest loss of intravascular plasma to extravascular
spaces produces undesirable hemoconcentration early
postoperatively.
• Bleeding because of preoperative polycythemia and
depletion of many clotting factors, extensive collateral
circulation, and damaging effects of CPB.
• Body weight is followed closely because transient fluid
retention is common, especially transannular patch.
Postrepair RV Pressure
Factors of PRV/LV
• Pulmonary arteriolar resistance
• Size of the LPA and RPA
• Presence & severity of localized or segmental stenosis
or incomplete distributions of pulmonary arteries
• Residual pulmonary trunk or RV outflow obstruction
• Increased flow through RVOT by residual shunting
and by pulmonary regurgitation
Tetralogy of Fallot
Special situation & controversies
• Rationale for use of postrepair PRV/LV
• Initial palliative operations
preferred median sternotomy in all age
• Palliation by beta-adrenergic blockade
2-6mg/kg/day
• Initial palliation by balloon valvotomy
• Monocusp valves beneath patches
Tetralogy of Fallot
Neurodevelopmental impairment
• Neurodevelopmental impairment is known in children
after palliative or corrective surgery for cyanotic heart
disease beyond infancy
• Preoperative impairment, however, due to prolonged
chronic cyanosis with thromboembolic or septic brain
damage, should be markedly reduced in Fallot patients
without preoperative complications and operated on
during infancy
• Influences of preoperative & perioperative conditions
with elevated circulating levels of proinflammatory
cytokines in hypoxemic patients might be also in part
responsible for damage to the brain
Tetralogy of Fallot
Surgical results
1. Survival
Early death ; recently less than 1%
Time-related survival ; good
2. Modes of death ; subacute heart failure
3. Risk factors for premature death
4. Heart block, arrhythmia, sudden death
5. Right ventricular function & aneurysm
6. Residual outflow tract obstruction
7. Left ventricular function & functional status
8. Residual VSDs & bacterial endocarditis
9. Pulmonary function
10. Reoperation & other reintervention
Postrepair Tetralogy of Fallot
Risk Factors for Premature Death
1. Very young age at repair
2. Older age at repair
3. Severity of “annulus” hypoplasia
4. Size of pulmonary artery
5. Transannular patch
6. Postrepair pRV/LV
7. Previous palliative operations
8. Multiple VSD ; 1-3%
9. Coexisting related cardiac anomalies
ECD, Down syndrome, MAPCA
10. Other risk factors ; small LV
Primary Repair of TOF
Advantages in early infancy
1. Avoidance of the risk of palliative operation
2. Prevention of shunt-induced PA stenosis
3. Obviation of the need to take down shunt
4. Early relief of RV hypertension
5. Avoidance of excessive LV volume load
6. Elimination of Rt-to-Lt shunting across VSD
Tetralogy of Fallot
Benefits of early complete repair
• Normal growth and development of organs
• Elimination of hypoxemia
• Less need for extensive right ventricular muscle
excision
• Better late left ventricular function
• Decreased incidence of late dysrrhythmias
Tetralogy of Fallot
Late problems after repair
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Late death, sudden cardiac death
Redo operation
Aortic root dilation, AR and AVR
Residua, sequelae ( PR, TR, RVOTO, VSD)
Arrhythmias (SSS, CAVB, AF, AFL, VT)
Impaired cardiopulmonary performance
Impaired autonomic nervous system
Ventricular dysfunction (RV, LV failure)
Infective endocarditis
Results after TOF Repair
Risk factors for late death
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Residual VSD
Residual RV outflow stenosis
Severe PR
Severe TR
Older age at repair
Previous Potts, or Waterston shunt
Tetralogy of Fallot
Considerations in adult
• Collaterals or preexisting shunts lead to increased
pulmonary blood flow, and together with myocardial
hypertrophy and myocardial hypoxia, they lead to
reduced biventricular function.
• Impaired ventricular function, severe hypoxemia, and
tricuspid regurgitation are associated with a higher
operative mortality, whereas the influence of age at the
time of operation is controversially
• Cyanosis and erythrocytosis lead to thrombosis,
infective endocarditis, stroke, brain abscess, myocardial
fibrosis, impaired ventricular function, and multiorgan
dysfunction could be the most important risk factor
Tetralogy of Fallot
Risk factors in adult
• Prolonged cyanosis causes myocardial and other organ
dysfunction
• Heart is chronically volume overloaded, especially in
previous palliative procedures and aortopulmonary
collaterals
• Bleeding tendency is also important
• The noncompliant hypertrophic adult right ventricle
seems to tolerate pulmonary valve regurgitation poorly,
the second significant predictor of early mortality being
the need for right ventricular outflow patch
• The native pulmonary valve is of course preserved and
repaired whenever possible
Results after TOF Repair
Causes of sudden death
• Bradyarrhythmias such as complete AV block,
bifascicular block, SSS
• VT and residual RVOTO and RV dysfunction
• Complex ventricular arrhythmias by Holter
monitoring
• Monomorphic VT and severe PR, peripheral
PS, RV dilation, QRS duration more than
180ms
Arrhythmia & Sudden Death
Approaches after TOF repair
• QRS
Easy to measure
Reflects RV size
Dynamic nature, QRS change important
New QRS cutoff values for contemporary cohorts
• QT dispersion
Refines risk stratification
Less dynamic
May reflect initial ventriculotomy scar/ VSD closure
Sudden Cardiac Death
Mechanisms of SCD after TOF repair
1. SCD & sustained VT in common
Electrophysiologic profile
Long QRS
QRS change
QT dispersion
Hemodynamic substrate
PR moderate/ severe
Cardiomegaly/RV dilation
2. SCD different from sustained VT patient;
olde age at repair
3. Overlap between AF/AFL/sustained VT & SCD
Tetralogy of Fallot
Causes of ventricular dysfunction
• LV dysfunction
• Secondary to inadequate myocardial protection during
initial repair
• LV volume overload due to longstanding palliative
shunt or residual VSD
• Myocardial fibrosis because of longstanding cyanosis or
RVOTO
• RV dysfunction
• Residual RVOTO
• Longstanding PR , TR
• Surgical scar, RV and /or RVOT patching, aneurysm
Autonomic Nerve System
Impairment after TOF repair
• Reports demonstrating depressed heart rate
variability and baroreflex sensitivity suggest
that the autonomic nervous system change
may also involved in arrhythmogenesis
• Also depressed heart rate was observed in
repaired TOF patients during exercise and
pregnancy
Aortic Root Dilation
Late after TOF repair
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Shunt to repair time interval
Male gender
Pulmonary atresia
Right aortic arch
Aortic regurgitation
LV enlargement
Tetralogy of Fallot
Mechanisms of aortic root dilation
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Underlying abnormality
Reciprocal morphogenesis of Aorta/PA
Increased flow from both ventricle
Abnormal morphology
Intrinsic medial abnormality
Acquired hemodynamic influences
Increased flow through aorta
Increased volume/ pulsatility
Infective endocarditis
Surgical damage
Residual VSD
Pulmonary Artery Lesions
After TOF repair
• Incidence of reoperation ; 5~14%
• Reasons of restenosis of RVOT
1. Restricted growth of RVOT
2. Miscalculated sizing of RVOT
3. Angulation & stenosis of LPA
4. Compression/angulation of PA caused by
RV hypertrophy or dilation
5. Most common location is pulmonary
bifurcation or origin of PA branch.
Pulmonary Artery Stenosis
Branch stenosis after TOF repair
1. RV dilation, pulmonary regurgitation after
transannular patch is primary phenomenon.
2. Pulmonary outflow dilate & elongate craniad,
and rotate to left resulting in kinking and
obstruction of previous normal left pulmonary
artery.
Left pulmonary Artery Stenosis
 Operative principle
1. Removal of redundancy at the kinking point
2. Effective shortening of the dilated and elongated
pulmonary trunk by reduction angioplasty or
conduit of shorter length
3. Division of intact ligamentum arteriosum
4. Conduit reconstruction of the RVOT with shortening
pulmonary trunk allowing LPA to be pulled down,
or reimplant LPA proximally with favorable angle.
RVOT Aneurysm
 Complications
• Airway compression
• Pulmonary perfusion asymmetry
• Thromboembolism
• Ventricular dysfunction
• Increase of pulmonary insufficiency
• Rupture
Unilateral Absence of PA
Pathogenesis
• The proximal pulmonary artery branches develop from
the proximal sixth pharyngeal arches.
• Nonconfluence of the pulmonary arteries may be due to
regression of the sixth arch segment as part of
conotruncal abnormalities.
• There was no channel from the right ventricle to a main
branch pulmonary artery with a disconnected PA
• Dissection to pulmonary hilus revealed an identifiable
patent artery.
• There is high incidence in this postmortem study of right
aortic arch and an aberrant subclavian artery
Unilateral Absence of PA
Pathophysiology
• The importance of previous ductal flow and the loss of
pulmonary arterial flow with duct closure after birth.
• The prevalence of a diverticulum of the innominate
artery was viewed as evidence of previous ductdependent arterial flow.
• The diverticulum represented a fetal systemic blood
supply to the affected lung through the distal part of
the sixth aortic arch.
• Early repair is the key in treating this anomaly because
of the risk of early obstructive pulmonary disease and
to avoid pulmonary hypertension or ultimate sacrifice
of the affected lung.
TOF with Flap Valve VSD
 Definition
A subset of TOF characterized by a thick, fibrous flap
hinged on the right side of a large VSD that narrows the
interventricular communication and thereby limits rightto-left shunting
 Morphology
• A fibrous flap is attached posteriorly to the aortic margin
of VSD, and its inferior margin may or may not be fused
with the base and superior margin of the anterior
tricuspid leaflet.
• Elsewhere, the flap is unattached, and it rarely plays any
part in tricuspid function
• It can hinge freely toward the right, but its thickness and
bulk prevent movement through the VSD