Tetralogy of Fallot postoperative complications & management

Dr Virbhan BalaiSR (Cardiology), NHI Delhi

Tetralogy of FallotIntroduction TOF is the MC form of cyanotic CHD after 1 year of age. Incidence approaching 10% of all forms of CHD. The defect is due to antero-cephalad deviation of the

outlet septum resulting in the following four features: 1. Non restrictive VSD - Usually subaortic2. Overriding aorta (but < 50%)3. RVOTO which may be infundibular, valvular, or (usually)

combination of both4. RVH

Associated lesions include Secundum ASD Additional muscular VSDRight aortic arch -25%Anomalous (can be dual) LAD (3%) which may necessitate a

conduit type of repairComplete AVSD (rare, usually in association with Down

syndrome). Pulm art hypoplasia or absent usually leftDeletion of chromosome 22q11 (previously called Di George

syndrome)- Approx. 15% of pt`s with ToF Frequent early onset of depression or psychiatric disease

Clinical Course (Unrepaired)Presentation as an Un-operated PatientRare US, can be seen in immigrantsMild pulmonary obstruction and mild cyanosis (pink

tetralogy) - diagnosis may not be made until adult life.It is usually mistaken for a small VSD because of the

loud precordial murmur. Severe RVOTO but abundant aorticopulmonary

collaterals may present late with cyanosis & loud cont murmur.

Postsurgical PresentationThey are usually asymptomatic. Exercise limitation Atrial and/or ventricular arrhythmias imply

hemodynamic difficulties.

Clinical Features and Evaluation

Clinical ExaminationThe typical post repair patient has a soft ESM

from the RVOT. Low-pitched, delayed diastolic murmur in the

pulmonary area is consistent with PR. Usually have an absent P2 The pt may have a PSM of a VSD patch leak. High pitched, diastolic murmur of AR

The occasional adult pt may present having palliative shunt only.

Such pts usually have cyanosis and clubbing. If the shunt is patent, a continuous murmur

may be heard. In the presence of a prior classic Blalock-

Taussig shunt, the brachial and radial pulses may be diminished or absent on that side.

ElectrocardiogramIn pt`s with trans ventricular repairs (the norm

until the 1990s), complete RBBB is almost always present, in which case QRS duration may reflect the degree of RV dilation.

A QRS duration of ≥180 ms has been identified as a risk factor for sustained VT & SCD.

The presence of AFL or AF or of sustained VT reflects severe hemodynamic difficulties.

Chest X-Ray

The heart size is usually normal. Cardiomegaly usually reflects important PR

and/or TR. The aortic arch is right sided in 25% of cases.

Initial Surgical Repair

Complete repair is considered-1. In palliated patients without irreversible PAH

or unfavorable pulmonary artery anatomy. 2. As a primary operation, usually performed in

the first year of life.

Complete repair consists of- 1. VSD closure 2. Relief of RVOT obstruction.

• Primary repair between 6 and 18 months• Perioperative mortality < 1%.• Late survival after tetralogy repair is excellent,

with a 35-year survival of 85%.

Palliative procedures to increase pulmonary blood flow

Blalock–Taussig shunt: classic or modified—subclavian artery to PA end-to-side or with interposition graft, respectively;

Waterston shunt: ascending aorta to right PA shunt;

Potts shunt: descending aorta to left PA shunt

CLASSIC BT shunt

POTTS SHUNT WATERSTON SHUNT

Occasionally, an extracardiac conduit must be placed from the right ventricle to the pulmonary artery when an anomalous coronary artery crosses the RVOT.

If the pulmonary valve itself is abnormal, a pulmonary valvotomy or pulmonary valve resection may be necessary.

Effort should be made to preserve the pulmonary valve during the primary operation when performed in infancy.

A PFO or small ASD is usually closed. When complete repair is performed in adulthood, pulmonary

valve replacement may be required if the native pulmonary valve integrity is disrupted .

Surgical Procedures for Repair of TOF in Adults

Pulmonary valve replacement Heterograft (porcine or pericardial) or homograft Mechanical PVR in patients who require warfarin anticoagulation for other

reasons. This procedure has been associated with late malfunction from pannus formation.

Patch augmentation of the pulmonary annulus for proper prosthetic valve sizing

Subvalvular obstruction or pulmonary artery stenosis Resection of subvalvular obstruction and/or patch augmentation of the RVOT,

pulmonary annulus, main or branch pulmonary arteries Usually occurs in combination with PVR

Residual/recurrent VSD closure Direct suture Patch revision

AVR (tissue or mechanical) for aortic regurgitationReplacement of ascending aorta for dilatation

Tube graft Bentall procedure (composite valved conduit with

coronary reimplantation)Aneurysm or pseudoaneurysm formation of RVOT

Resection and patch replacementAtrial arrhythmias

Maze procedure or 1 of its modifications

Ventricular arrhythmias (ventricular tachycardia, ventricular fibrillation) Preoperative EP testing and ablation in the catheterization laboratory If unsuccessful, intraoperative mapping and ablation are performed Focus is most often in the RVOT between the VSD patch and the

pulmonary annulus Postoperative placement of an ICD for patients at high risk of sudden death

Tricuspid valve repair for significant tricuspid regurgitation Tricuspid valve replacement for a markedly abnormal tricuspid valve Closure of residual PFO or ASD, especially if there is cyanosis, history

of paradoxical embolism, or anticipated need for a permanent pacemaker or ICD.

Key postoperative issuesResidual pulmonary regurgitationRV dilation and dysfunction from pulmonary

regurgitation, possibly with associated TRResidual RVOT obstructionBranch pulmonary artery stenosis or hypoplasiaSustained VTSudden cardiac deathAV block, atrial flutter, and/or atrial fibrillationProgressive ARSyndromal associations.

Common complications in adulthood

PR: Significant PR is almost always encountered following a transannular patch repair.

PR is usually well tolerated for years. Severe chronic PR, however, eventually leads to

symptomatic RV dilation and dysfunction.The severity of PR and its deleterious long-term

effects are augmented by co-existing distal PA stenoses or PAH (the latter is uncommon).

† Residual RVOTO: This can occur at the infundibulum, at the level of the pulmonary valve and main pulmonary trunk, distally, beyond the bifurcation, and occasionally into the branches of the left and right PAs (the latter frequently because of sequelae from previous palliative surgery).

RV dilation and dysfunction: RV dilation is usually due to residual longstanding free PR+RVOTO.

Significant TR may occur as a consequence of RV dilation, which begets more RV dilation.

† Residual VSD: This can be due to partial patch dehiscence or failure of complete closure at the time of surgery; it may lead to LV volume overload.

† Aortic root dilation with AR: Aortic root dilation (progressive) is seen in 15% of adults late after repair and relates to both intrinsic abnormalities of the aorta (cystic medial necrosis) and increased flow (i.e. patients with pulmonary atresia).

It commonly leads to AR and rarely to aortic dissection.

LV dysfunction: Due to longstanding cyanosis before repair and/or inadequate myocardial protection during repair (old era), LV volume overload from longstanding palliative arterial shunts, residual VSDs, and/or AR.

It can also be the result of an adverse ventricular–ventricular interaction (PR).

† Atrial/ventricular tachycardia and SCD: This is related to progressive haemodynamic problems and/or surgical scarring, and thus is seen with increasing frequency with longer follow-up.

SCD is reported in 1–6% of cases [in most instances due to VT/ventricular fibrillation (VF)], accounting for approximately a third to a half of late deaths.

† Endocarditis: Endocarditis is rare.

Gatzoulis and colleagues reported RF for SCD in 793 pt`s with repaired TOF from six centers in the UK & found that older age of repair and QRS duration 180 ms were independent predictors of sudden death.

Multiple other organ systems may be affected, and it is not uncommon for ACHD patients with repaired TOF to have renal, hepatic, and pulmonary comorbidities.

Incidence of Complications Post-repair

Problems and Pitfalls in the Patient With Prior Repair

The following problems occur in patients after repair of tetralogy of Fallot: Cardiomegaly;- on chest x-ray should prompt the search for a residual

hemodynamic lesion (commonly pulmonary regurgitation). The development of arrhythmias (atrial or ventricular) should prompt the

search for an underlying hemodynamic abnormality (commonly PR). Diagnostic confusion may occur in the context of DORV, in which the aorta

overrides the right ventricle by more than 50%. In such cases, the VSD patch is more extensive and predisposes to the presence of postoperative sub aortic obstruction, which should be carefully excluded.

Hypoxemia in postoperative patients should prompt a search for a PFO or ASD with a right-to-left shunt.

The presence of RV enlargement or dysfunction and the presence of important TR should prompt the search for a residual hemodynamic lesion (commonly PR).

postoperative some pt`s may have LV dysfunction.

This may related to-Prolonged cardiopulmonary bypass, Poor myocardial protection from an early surgical

era, or Trauma to a coronary artery at the time of repair,

or It may be secondary to severe RV dysfunction.

Recommendations for Evaluation and Follow-Up of the Repaired Patient

Class I1. Pt`s with repaired TOF should have at least annual follow-up with a

cardiologist who has expertise in ACHD. (Level of Evidence: C)2. Pt`s with TOF should have echocardiographic examinations and/or

MRIs performed by staff with expertise in ACHD. (Level of Evidence: C)

3. Screening for heritable causes of their condition (eg, 22q11 deletion) should be offered to all pt`s with TOF. (Level of Evidence: C)

4. Before pregnancy or if a genetic syndrome is identified, consultation with a geneticist should be arranged for pt`s with TOF. (Level of Evidence: B)

5. Pt`s with unrepaired or palliated forms of tetralogy should have a formal evaluation at an ACHD center regarding suitability for repair. (Level of Evidence: B)

The frequency, although typically annual, may be determined by the extent and degree of residual abnormalities.

Appropriate imaging (2D ECHO annually in most cases and/or MRI every 2 to 3 years) should be undertaken by staff trained in imaging of complex congenital heart defects.

An ECG should be performed annually to assess cardiac rhythm and to evaluate QRS duration.

Periodic cardiopulmonary testing may be helpful to facilitate serial follow-up of exercise capacity and to evaluate the potential for exercise induced arrhythmias.

Other testing should be arranged in response to clinical problems, particularly a Holter monitor if there is concern about arrhythmias.

Recommendation for Imaging

Class 1 Comprehensive echo imaging should be performed in a regional ACHD center

to evaluate the anatomy and hemodynamics in pt`s with repaired TOF . (Level of Evidence: B)

The presence and severity of residual RVOT obstruction and PR can usually be assessed along with the presence or absence of TR.

The TR velocity facilitates measurement of the RV pressure. A residual VSD may be seen. RV volume and wall motion are not reliably quantified by standard techniques,

although size and function can be determined qualitatively. Doppler measurement of the RVMPI useful adjunct for serial assessment of RV

systolic function. Atrial size can be assessed. Aortic root dilation and AR should be sought and evaluated at regular intervals.

MRI is now seen as the reference standard for assessment of RV volume and systolic function. It can be helpful in assessing the severity of PR and in

evaluating important associated pathology, especially involving the pulmonary arteries and the ascending aorta.

Left-sided heart disease can also be evaluated. CT scan - makes similar measurements of RV volume and

systolic function and is potentially helpful in pt`s who cannot have an MRI, although bcz of the higher radiation exposure, it is not suitable for serial measurements.

Recommendations for Diagnostic and Interventional Catheterization for Adults With TOF

Class I1. Catheterization of adults with TOF should be performed in regional centers with

expertise in ACHD. (Level of Evidence: C)2. Coronary artery delineation should be performed before any intervention for the

RVOT. (Level of Evidence: C)Class IIb3. In adults with repaired TOF, catheterization may be considered to better define

potentially treatable causes of otherwise unexplained LV or RV dysfunction, fluid retention, chest pain, or cyanosis. In these circumstances, transcatheter interventions may include:

a. Elimination of residual shunts or aortopulmonary collateral vessels. (Level of Evidence: C)

b. Dilation (with or without stent implantation) of RVOT obstruction. (Level of Evidence: B)

c. Elimination of additional muscular or patch margin VSD. (Level of Evidence: C)d. Elimination of residual ASD. (Level of Evidence: B)

Recommendations for InterventionalCatheterization

Class I1. Interventional catheterization in an ACHD center is indicated for

patients with previously repaired tetralogy of Fallot with the following indications:

a. To eliminate residual native or palliative systemic– pulmonary artery shunts. (Level of Evidence: B)

b. To manage coronary artery disease. (Level of Evidence: B)Class IIa2. Interventional catheterization in an ACHD center is reasonable

in patients with repaired tetralogy of Fallot to eliminate a residual ASD or VSD with a left-to-right shunt greater than 1.5:1 if it is in an appropriate anatomic location. (Level of Evidence: C)

Diagnostic Catheterization Cont.. Assessment of hemodynamics Assessment of pulmonary blood flow and resistance Assessment of the nature of RV outflow or pulmonary artery obstruction Delineation of coronary artery origin and course before any interventional

procedure Assessment of ventricular function and presence of residual septal

defects, as well as assessment of the degree of mitral regurgitation or AR. Assessment of the significance of flow across a PFO or ASD and its

potential elimination Performance of coronary angiography, with potential to eliminate

symptomatic obstructive lesions Assessment of pulmonary regurgitation and right-sided heart failure.

Branch Pulmonary Artery Angioplasty

Balloon angioplasty of a branch pulmonary artery results in intimal and medial dissection and subsequent inflammatory repair and increase in vessel size.

Dilation may be considered when RV pressure is more than 50% of the systemic level or at lower pressure when there is RV dysfunction.

Balloon PA angioplasty may also be considered when there is unbalanced pulmonary blood flow greater than 75%, 25%, or otherwise unexplained dyspnea with severe vascular stenosis.

PA balloon angioplasty may be an effective way to reduce obstruction to PBF, thereby increasing PVC and decreasing PVR.

Balloon angioplasty is usually effective for intermediate-branch pulmonary artery stenoses.

Post deployment anti inflammatory or anti proliferative/anticoagulant strategies remain undefined.

Stent redilation has been shown to be effective in selected patients as late as 10 years after implantation.

These techniques has recently been extended to adults with very distal segmental pulmonary artery stenoses and appears promising.

The transcatheter approach to the management of residual muscular or patch margin VSDs.

Exercise Testing Exercise testing may be used to assess functional

capacity objectively and to evaluate possible exertional arrhythmias. Serial evaluations may be helpful.

Management Strategy for the Patient With Prior Repair

Medical TherapyMost patients need no regular medication in

the absence of significant residual hemodynamic abnormality.

Heart failure medications may be necessary in the setting of RV and LV dysfunction.

Recommendations for Surgery for AdultsWith Previous Repair of TOF

Class I1. Surgeons with training and expertise in CHD

should perform operations in adults with previous repair of TOF. (Level of Evidence: C)

2. PVR is indicated for severe PR and symptoms or decreased exercise tolerance. (Level of Evidence: B)

3. Coronary artery anatomy, specifically the possibility of an anomalous LAD across the RVOT, should be ascertained before operative intervention. (Level of Evidence: C)

Class IIa1. PVR is reasonable in adults with previous TOF,

severe PR, and any of the following:a) Moderate to severe RV dysfunction. (Level of Evidence:

B)b) Moderate to severe RV enlargement. (Level of

Evidence: B)c) Development of symptomatic or sustained atrial and/or

ventricular arrhythmias. (Level of Evidence: C)d) Moderate to severe TR. (Level of Evidence: C)

2. Collaboration between ACHD surgeons and ACHD interventional cardiologists, which may include preoperative stenting, intraoperative stenting, or intraoperative patch angioplasty, is reasonable to determine the most feasible Tt for pulmonary artery stenosis. (Level of Evidence: C)

3. Surgery is reasonable in adults with prior repair of TOF and residual RVOT obstruction (valvular or subvalvular) and any of the following indications:

a. Residual RVOT obstruction (valvular or subvalvular) with peak instantaneous echocardiography gradient greater than 50 mm Hg. (Level of Evidence: C)

b. Residual RVOT obstruction (valvular or subvalvular) with RV/LV pressure ratio greater than 0.7. (Level of Evidence: C)

c. Residual RVOT obstruction (valvular or subvalvular) with progressive and/or severe dilatation of the right ventricle with dysfunction. (Level of Evidence: C)

d. Residual VSD with a left-to-right shunt greater than 1.5:1. (Level of Evidence: B)

e. Severe AR with associated symptoms or more than mild LV dysfunction. (Level of Evidence: C)

f. A combination of multiple residual lesions (eg, VSD and RVOT obstruction) leading to RV enlargement or reduced RV function. (Level of Evidence: C)

Indications for intervention after repair of tetralogy of Fallot

The need for re-intervention, usually for pulmonary valve insertion, increases after the second decade of life.

Pt`s with RV–to–pulmonary artery conduit repairs often require further intervention for conduit stenosis or regurgitation.

Indications for EP testing and ICD EP testing and/or ablation must be considered for symptomatic pt`s with

suspected or documented clinical arrhythmia, atrial or ventricular. An ICD should be implanted for sec. prevention of SCD (patients with cardiac

arrest or sustained VT) (IC). ICD implantation for pri. prevention remains controversial, and no ideal risk

stratification scheme has so far been developed. The following risk markers—although not consistently—have been reported:

Right and/or left ventricular dysfunction Extensive ventricular fibrosis (on CMR) QRS ≥180 ms Significant PR Non-sustained VT on Holter monitoring Inducible VT at EP testing Long-lasting palliative shunts Older age at time of repair.

Key Issues to Evaluate and Follow-Up

Recommendations for Arrhythmias: Pacemaker/Electrophysiology Testing Class I1. Annual surveillance with history, ECG, assessment of RV function, and

periodic exercise testing is recommended for patients with pacemakers/automatic implantable cardioverter defibrillators. (Level of Evidence: C)

Class IIa1. Periodic Holter monitoring can be beneficial as part of routine follow-up.

The frequency should be individualized depending on the hemodynamics and clinical suspicion of arrhythmia. (Level of Evidence: C)

Class IIb1. Electrophysiology testing in an ACHD center may be reasonable to define

suspected arrhythmias in adults with TOF. (Level of Evidence: C)

The 30-year survival rate from reoperations for the first 106 patients undergoing surgical repair was 91%.

Patients with TOF born prior to the early 1970s were often palliated with systemic artery to pulmonary artery shunts to increase pulmonary blood flow prior to the definitive repair.

Despite overall excellent hemodynamic outcomes after surgery for TOF, there remains a concerning incidence of unexpected sudden death during long-term follow-up .

VT appears to be the mechanism responsible for most of these events, although rapidly conducted IART (atrial flutter) or AV block may be responsible in some cases.

The incidence of sudden death for the adult tetralogy population can be estimated from several large series to be on the order of 2.5% per decade of follow-up.

Estimates of Sudden Death After Tetralogy of Fallot Surgery

Compromised AV conduction, with the hypothesis that Trauma to AV conduction tissues at the time of surgery (enough to cause permanent bifascicular block) could lead to late sudden death, presumably due to abrupt worsening of conduction with asystole.

By the 1980s, however, the emphasis shifted away from AV block toward VT as the more common mechanism for sudden death in tetralogy patients.

Potential Risk Factors for Sudden Death After TOF Surgery

In general high-risk tetralogy pt involves some combination of-1. Long-standing palliative shunts 2. Older age at the time of definitive surgery3. Abnormal RV hemodynamics (due to pulmonary

regurgitation and/or residual outflow obstruction) 4. High-grade ectopy on Holter monitor5. Inducible VT at electrophysiological study. 6. QRS duration greater than 180 ms.

Reproduction

Pregnancy is not advised in patients with unrepaired TOF.After repair of TOF, the prognosis for a successful

pregnancy is good provided there are no important hemodynamic residua and functional capacity is good.

A comprehensive, informed cardiovascular evaluation is recommended before each pregnancy.

Pregnancy is usually well tolerated even in the setting of severe pulmonary regurgitation, as long as RV function is no more than mildly depressed and sinus rhythm is maintained.

Pt`s with TOF have an increased risk of fetal loss, and their offspring are more likely to have congenital anomalies than offspring in the general population, especially in the setting of a 22q11.2 microdeletion.

Screening for 22q11.2 microdeletion should be considered in pt`s with conotruncal abnormalities before pregnancy to provide appropriate genetic counseling.

In the absence of a 22q11 deletion, the risk of a fetus having CHD is approximately 4% to 6%.

Fetal echocardiography should be offered to the mother in the second trimester.

Endocarditis Prophylaxis

The endocarditis risk in GUCH patients is substantially higher than in the general population, with marked variation between lesions.

Oral hygiene and regular dental review have an essential role in reducing the risk of IE.

Aseptic measures are mandatory during manipulation of venous catheters and during any invasive procedure.

It is currently recommended by expert consensus to limit antibiotic prophylaxis to pts with the highest risk of IE undergoing the highest risk procedures (IIaC).

† Patients with a prosthetic valve or a prosthetic material used for cardiac valve repair

† Patients with previous IE† Patients with CHD: A cyanotic CHD, without surgical

repair, or with residual defects, palliative shunts, or conduitsA CHD after repair with prosthetic material whether placed

by surgery or by percutaneous technique, up to 6 months after the procedure (until endothelialization)

A when a residual defect persists at the site of implantation of a prosthetic material or device by cardiac surgery or percutaneous technique.

The recommendation is limited to dental procedures requiring manipulation of the gingival or periapical region of the teeth or perforation of the oral mucosa.

Antibiotics are not recommended for respiratory tract, gastrointestinal, genitourinary, dermatological, or musculoskeletal procedures unless there is an established infection.

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