management of tetralogy of fallot
TRANSCRIPT
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