MANAGEMENT OF TETRALOGY OF FALLOT

Dr M S ADITYA

PREVALANCE

3.36% -9.27% of all congenital heart diseases

0.21-0.26/1000 live births(0.22) Most common cyanotic heart defect

to be seen in children beyond infancy Most common complex lesion to be

encountered in the adult population after repair

INTRODUCTION

Tetralogy of Fallot with absent pulmonary valve syndrome

Tetralogy of Fallot with common atrioventricular canal

Tetralogy of Fallot with pulmonary atresia

Tetralogy of Fallot with pulmonary stenosis

INTRODUCTION(CLINICAL) The degree of cyanosis is often related to the

severity of RVOTO. Patients who are already cyanotic become more

cyanotic than before as a result of worsening infundibular stenosis

Hypoxic spells may develop in infants. Growth retardation may be present if cyanosis is

severe. Brain abscess and stroke can occur but are rare. Subacute bacterial endocarditis is occasionally a

complication. Aortic regurgitation may develop in some patients,

particularly those with severe tetralogy of Fallot.

ANATOMY

VSD is a perimembranous malaligned VSD Additional muscular VSDs may be present RVOTO most frequently infundibular

(45%),only valvular(10%), combined( 30%) Pulm annulus and MPA is hypoplastic, PAs

are small with variable degrees of pulmonic stenosis, LPA stenosis is common

Abnormal coronaries are seen in 5% Associated defects include ASD, PDA, right

aortic arch,lSVC,unroofed coronary sinus,TV abnormalities,PAPVC, TAPVC,AVCD

GENETICS

Inheritance multi factorial, autosomal recessive or dominant

Mis-sense mutation in JAG1 expressed in right heart

Mutation in transcription factor NKX2.5

Microdeletion of 22nd chrmosome, more commonly associated with interrupted aortic arch

INVETIGATIONS

The number, size, and location of all VSDs

The severity and location of RVOTO The size and distribution of the

pulmonary artery The origins and branching pattern of

the coronary arteries The origin and distribution of all

sources of pulmonary blood flow, including MAPCAs

Natural history

Bertranou et al 66% 1 yr, 48% 3yr, 24%10yr

Median age at death is 9yrs

TOF natural history altered by palliative shunts and ICR

Blalock taussig(1945)

Potts shunt9(1946) Waterston

shunt(1954) Prostaglandin(197

6) ICR(1973)

PALLIATIVE SHUNTS

Palliative shunts

Neonates with TOF and pulmonary atresia Infants with hypoplastic pulmonary

annulus, which requires a transannular patch for complete repair

Children with hypoplastic PAs Unfavorable coronary artery anatomy Infants younger than 3 to 4 months

old who have medically unmanageable hypoxicspells

Infants weighing less than 2.5 kg

BLALOCK TAUSSIG shunt

Classic shunt involves RSCA in LAA and visa versa Infants older than 3 mths Modified involves placement of gore tex tube in

ipsilateral PA( < 3mths of age) Earlier series had exceptionally high mortatlity High incidence of PA distortion, PAH 33% Al jubair et al reported a series of 546 patients , 78

<1 yr,270 1wk-1 yr, 198>1 yr Hospital mortality of 2.9%,6.4<1wk, 3.7% 1wk-1

yr, 0.5%>1yr Shunt failure common in less than 3 kg, not

anticoagulated prior

BLALOCK TAUSSIG SHUNT

Taussig reported 20-28 yr follow up of patients operated between 1945-51

50% of patients were alive after 20 yrs 432 patients alive at 15 th yr were followed At 20 th yr 24 had died , 34 lost to follow

up 169 did not undergo further surgery, 227

complete repair 37% of shunt patients considered to be

doing well, 79% of ICR were well

OTHER SHUNTS

Central shunts easier to perform esp when PA was small

More prone for PAH and PA distortion Aneurysms of Pas which ruptured Chronic volume overload of

ventricles Difficult to take down from midline

sternotomy at time of complete repair

Phrenic nerve injury, RLN injury and others

BROCK CLOSED TRANSVENTRICULAR INFUNDIBULECTOMY AND OTHERS

Pulmonary infundibulectomy and valvotomy, leaving the VSD

Procedure was suitable in older patients Uniform flow in both PAs Pleurectomy, pleurodesis, used to stimulate

growth of trans pleural collateral vessels and improve crippling hypoxemia

Great omentum brought in contact with left lung

Formalin injection in PDA to maintain patency

TOF INDICATION FOR OPERATION ICR advisable before 3 yrs of age to

avoid polycythemia, brain abscess and death and long term complications

Primary Vs two stage surgery comparisons of risks essential

If shunt is performed prior ICR is carried out at 2-3 yrs of age

PULMONARY ARTERY SIZE

The McGoon ratio is determined by summing the diameter of the immediately prebranching portion of the right and left pulmonary artery and dividing this sum by the diameter of the descending aorta at the level of the diaphragm, all the measurements being taken in systole

PULMONARY ARTERY SIZE

RPA AND LPA can be considered non restrictive when combined diameter ratio is more than 2,mildly restrictive when ratio is 1.6,1 moderately rectrictive

PULMONARY ARTERY SIZE

The Nakata index or pulmonary artery index is determined by measuring the diameters of the right and left pulmonary arteries immediately proximal to the origin of the first lobar branches; the cross-sectional areas are then calculated, summed and divided by the body surface area

Index of 330±30mm2 in normal situation low output symptoms at <150mm2

POST REPAIR RV/LV

Peak pressure in RV/LV , to estimate residual obstruction

As low as possible desired 0.70 is acceptable if alternative is only

transannular patch Corresponds to a gradient of 40mmhg Estimated in late postop Related to pulmonary arteriolar resistance, RPA and

LPA size, and segmental and peripheral stenosis Determines long term result f operartion Practice is to accept RV/LV upto .85 post repair 30

mins after CPB

Z VALUE

Z value is the number of standard deviations that the patients annulus size is away from mean normal value

Annulus diameter is normalized to patients BSA

Determined according to cineangiograms or hager dilator estimation

Correlates with Post op RV/LV pressures

PRIMARY Vs TWO STAGE REPAIR Primary repair favoured when age more

than 3 mths except in special situations Pre op RV/LV estimated <0.63 transannular

patch not needed , child more than 6 mths ICR, younger patient shunt with later repair

If RV/LV >0.63 chance of requiring transannular patch is increased, if BSA is more than .38m2 ICR

70 % CL of probability of hospital death after primary and 2 stage repair

TOTAL REPAIR OF TOF

Era of corrective surgery was ushered in by Lillehei in 1955

Casteneda et al at boston children hospital,1n 1970 advocated primary reapir of TOF at any age

Approaches1. Right atrial2. Vertical incision in outflow of RV3. Transverse ventriculotomy

TOTAL REPAIR OF TOF

Right atrial approach allows1. Infundibular dissection2. Repair of VSD3. Assesment of Pulmonary valve4. Avoids cutting of RCA and

ventriculotomy scar5. Damage to TV is an issue6. Useful when transannular patch is

not needed

TOTAL REPAIR OF TOF

RVOT1. Infundibular dissection2. Pulmonar y valvotomy VSD1. Closed with a preclotted dacron

velour patch

TOF REPAIR TRANSANNULAR PATCH After closing VSD hegar dilators are placed to

determine the narrowest portion of RVOT If the post opRV/LV is predicted to be equal to

or greater than 0.85 , diffuse hypoplasia, infundibular + valvar+annular, transannular patch is placed

Pulmonary arteriotomy extended to widest part of the pulmonary trunk, which is opposite the RPA

¾ diameter of ascending aorta Patch can be constructed from pericardium or

dacron patch

TOTAL REPAIR OF TOF CORONARY ANOMALIES Anomalous LAD from RCA crossing

RVOT close to pulmonary ring Usual course of first part of LAD

inspected Dissection of the anomalous artery

from its bed done right ventriculotomy is done by giving incision beneath it

Valved conduit is used to bypass the area if required

INCREMENTAL RISK FACTORS FOR HOSPITAL DEATH Presence of pulmonary artery problems1. Diffuse severe hypoplasia2. Severe and multiple localized areas of

hypoplasia3. Iatrogenic stenoses4. Incomplete distribution of cantral and

hilar portions of Pas Pot op outcomes related to high

postRV/LV ratio, surgical complexity, hypoperfusion of lung

INCREMENTAL RISK FACTORS FOR HOSPITAL DEATH More than one previous palliative

surgery1. Highest with central shunts and b/l

plerectomy, brock procedure,BT+waterston shunts

Size of patient(BSA) in creased susceptibility to CPB

High hematocrit, reflects arterial hypoxia, and widespread effects esp clotting systems.(0.45-.55 double sthe risk of death)

INCREMENTAL RISK FACTORS FOR HOSPITAL DEATH Use of transannular patch1. Could indicate more sevre PS2. Diastolic over load of RV Early date of operation Absent pulmonary valve Major associated cardiac anomalies In pulmonary atresia use of vlaved

conduit and high postop RV/LV

Incremental risk factors for late functional status Pulmonar y valve incomptence Age at repair RV/LV ratio ( residual gradient) Multiple VSds

STRATEGIES TO PROMOTE GROWTH OF Pas Systemic to PA shunts Brock procedure RVOT patch, conduit Trans catheter approach

LONG TERM FOLLOW UP

Survival Freedom from re intervention PR and requirement for PV replacement Ventricular arrhythmias and sudden death Atrial arrhythmias Complete heart block Ventricular function Quality of life Bacterial endocarditis

SURVIVAL

Series form alabama at 1 mth, 1 yr,5 yr,20 yr at 93%,93%,92%,87%(814 patients)

Rat e of post op CHB % in earlier series, now around 1%

REINTERVENTION

VSD RVOUTFLOW AND PA obstruction PR TR AR RV dysfunction LV dysfunction RVOt aneurysm Pulmonary hypertension

Most residual VSDs tend to be small and less seen in modern era

Dilatation of aortic root, sub pulmonary VSD, patients present with AR in long term

Surgical injury to AV PA stenosis at site o f arterioplasty,

MPA, just distal to transannular patch known to require reintervention

Aneurysmal bulging of patch along with PR

PULMONARY REGURGITATION

Inevitable consequence of trans annular patching and pulmonary valvatomy

Post op PR is seen in 60-90% Long term PR can have adverse impact esp in

children operated at older age Requirement for pulmonary valve replacement1. Exercise intolerance2. Progressive cardiac enlargement3. Aneurysmal dilatation of outflow tract4. Onset of TR, atrial and ventricular arrhythmias

PULMONARY REGURGITATION

Mayo clinic has has reviewd 42 patients who underwent PV replacement

Mean interval between TOF repair and PV replacement was 10 yrs

Exercise in tolerance 58%, right heart failur 21%, arrhythmia14%, and syncope 10%, RV dilatation 7%

Functional class improvement was seen Some patients required reimplantation Arrhythmia control was superior Age at time of PV replacement increased when

operated younger

PULMONARY REGURGITATION

Some degree of regurgitation inevitable

Trivial to mild PR may be tolerated in long term

Tendancy to delay PV repalcement Asymptomatic patients? Restrictive physiology in post repair

patients reduces PR

VENTRICULAR ARRHYTHMIAS AND SUDDEN CARDIAC DEATH Risk of sudden cardiac death 25 to 100 times

more Risk of sudden death late after surgery is 5% Older age of repair Increased fibrosis in RV with age Extent of surgery and ventriculotomy scar QRS duration >180msec,RV enlargement Severe PR, outflow aneurysms Inducible monomorphic VT Moderate, severe LV dysfunction more Abnormal adrenergic activity

ATRIAL FIBRILLATION AND FLUTTER Older age at repair, hemodynamic

abnormalities and increased morbidity, older age

Atrial arrhythmias associated with CHF, reoperation,,VT, stroke and death

Higher mean right atrial volume Significant PR

VENTRICULAR FUNCTION

Age of patient Degree and duration of hypoxemia

exposure Duration and size of shunt Size of ventriculotomy scar and

muscle resected Postop PR

INFECTIVE ENDOCARDITIS

Endocarditis may affect aortic valve, TV,VSD,PA

TOF accounts for 16% of IE in CHD 1.3% f repaired TOF have IE over 30

yrs ENDOCARDITIS PROPHYLAXIS

RECOMMENDED

UNUSUAL COMPLICATIONS

Coronary-RV fistulae or PA fistulae reported

DCRV situation seen Subaortic stenosis Aneurysmal dilatation of subclavian

aretery at the systemic end