Tetralogy of Fallot

Seoul National University HospitalDepartment 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 : 1st description in 1672 Fallot : Known tetralogy in 1888 Blalock & Taussig : 1st surgical intervention in 1945 Sellors & Brock : Closed valvotomy & infundibulectomy in 1948 Lillehei & Varco : 1st repair by cross circulation in 1954 Mayo group : 1st repair by pump oxygenator in 1955 Kirklin : Conduit use for TOF+PA in 1966

Tetralogy of Fallot

Pathophysiology• Tetralogy of Fallot consists of a large VSD, RV

OTO, 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 InfundibulumRole & 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 InteractionRV & LV interaction -Cross-talk-• While the deeper layer of myocardial fibers are se

parated, 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 FallotSurgical 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

VSD

VSD

PA Aorta

Tetralogy of Fallot Genetic syndromes & outcome• Approximately 10% to 15% of TOF patients carry a 22q1

1 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 FallotClinical 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 FallotNatural history 1. Incidence : One of the most common CHD 3~6/10000 births (5%~10% of CHD) 2. Symptoms & survival : 25% death in 1 yr 40% death in 3 yrs 70% death in 7 yrs 95% death in 40 yrs 3. Hypoxic spell : Hyperactivity of infundibulum in the 1st year of life & sudden reduction of SVR 4. Pulmonary artery thrombosis ; in severely polycythemia 5. Pulmonary vascular disease ; rarely 6. 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 FallotAim of repair• First, the procedure must relieve the right ventricular h

ypertension ( 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 FallotOperative 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

Systemic-pulmonary shunts

• Various positions of the usual systemic-pulmonary arterial shunts for augmenting pulmonary blood flow

Tetralogy of Fallot

Systemic-Pulmonary Shunts Via median sternotomy

Tetralogy of Fallot

• Anatomic substrate of repair from right ventricular approach

Anatomy

Tetralogy of Fallot

• Anatomic substrate of repair from right atrial approach

Anatomy

RVOT ReconstructionPrinciples• The diameter of annulus with a Hegar dilator that pass

es snugly but not tightly through it.• Generally, a transannular patch should not be placed w

hen Z value is larger than -3.• When a polyester tube is used, one is selected whose dia

meter corresponds to a Z value of 0 to +2. • The patch when properly trimmed, its convexity is ensu

red 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 ReconstructionApplication of monocusp patch• Transannular patching is often necessary for reconstruc

tion 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 FallotSurgical repair

Tetralogy of Fallot

• The rectangular patch when properly trimmed, its convexity is ensured in all direction, as relatively “square cut” of its distal end.

Operative technique

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

Tetralogy of Fallot Pulmonary valve saving

Pulmonary valve-sparing

(A) Pulmonary arteriotomy. (B) Autologous pantaloon pericardial patch. (C) Completed pulmonary artery pantaloon patch.

Tetralogy of Fallot

Tetralogy of FallotPostoperative care• Patients have a tendency to increase their interstitial, pleural,

& peritoneal fluids early postoperatively.• The hemodynamic state is assessed continuously and managem

ent 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 o

r incomplete distributions of pulmonary arteries• Residual pulmonary trunk or RV outflow obstruction • Increased flow through RVOT by residual shunting an

d 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 FallotNeurodevelopmental 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 FallotSurgical 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

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

Postrepair Tetralogy of Fallot

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 FallotLate problems after repair• 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 RepairResults after TOF RepairRisk factors for late death• Residual VSD• Residual RV outflow stenosis• Severe PR• Severe TR• Older age at repair• Previous Potts, or Waterston shunt

Tetralogy of FallotConsiderations 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 FallotRisk factors in adult• Prolonged cyanosis causes myocardial and other organ dysfun

ction• 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 t

olerate 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 mo

nitoring• Monomorphic VT and severe PR, peripheral P

S, RV dilation, QRS duration more than 180ms

Arrhythmia & Sudden DeathApproaches 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 DeathMechanisms 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 FallotCauses of ventricular dysfunction• LV dysfunction• Secondary to inadequate myocardial protection during

initial repair• LV volume overload due to longstanding palliative shu

nt or residual VSD• Myocardial fibrosis because of longstanding cyanosis o

r 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 va

riability 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 DilationLate after TOF repair• Shunt to repair time interval• Male gender• Pulmonary atresia• Right aortic arch• Aortic regurgitation• LV enlargement

Tetralogy of FallotMechanisms of aortic root dilation• 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 LesionsAfter 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 PAPathogenesis• The proximal pulmonary artery branches develop from t

he proximal sixth pharyngeal arches. • Nonconfluence of the pulmonary arteries may be due to r

egression 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 PAPathophysiology• The importance of previous ductal flow and the loss of pulmo

nary arterial flow with duct closure after birth. • The prevalence of a diverticulum of the innominate artery wa

s viewed as evidence of previous duct-dependent 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 hi

nged on the right side of a large VSD that narrows the interventricular communication and thereby limits right-to-left shunting

Morphology• A fibrous flap is attached posteriorly to the aortic margi

n 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