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Atrial Septal Defect (ASD)

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Types of ASD

• Robbins, Cotran & Kumar Pathologic Basis of Disease, p. 504

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Pathophysiology

• Pulmonary blood flow may be 2-8x normal (Qp/Qs can exceed 3:1 in large defects)
• Right heart volume overload - right atrial and right ventricular dilation and hypertrophy
• Increased flow through the pulmonary valve causes a flow murmur
• Over decades, sustained right-sided pressure and volume overload can lead to pulmonary arterial hypertension - less common in ASDs than VSDs, but possible
• Paradoxical right-to-left shunting can occur transiently during increased intrathoracic pressure (Valsalva, coughing), risking paradoxical embolism and stroke
• In advanced disease: Eisenmenger syndrome (reversal of shunt to right-to-left, cyanosis) - though this is far less common than with VSDs
• Sabiston Textbook of Surgery, p. 2564; Robbins, p. 504-505

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Clinical Presentation

• Dyspnea on exertion - the most common presenting symptom
• Fatigue and exercise intolerance
• Palpitations, atrial fibrillation/flutter - due to atrial dilation and volume overload
• Syncope or stroke - from atrial arrhythmias or paradoxical embolism
• Signs of right heart failure: peripheral edema, elevated JVP, hepatomegaly in late disease
• More than 70% of patients are functionally impaired by the 5th decade if untreated
• Goldman-Cecil Medicine, p. 980

Physical Examination

• Goldman-Cecil Medicine, p. 984

Investigations

• ECG: Incomplete right bundle branch block (rSR' pattern in V1) is characteristic; right axis deviation; prolonged PR interval, atrial fibrillation/flutter with advanced disease
• Chest X-ray: Pulmonary vascular plethora (bilateral increased lung markings), dilated main pulmonary artery and branches, right atrial and right ventricular enlargement
• Echocardiography (TTE/TEE): Definitive diagnostic tool - identifies the ASD location and size, quantifies the shunt ratio (Qp/Qs), estimates pulmonary artery pressures, and assesses RV function. Note: sinus venosus ASDs can be missed on TTE and require TEE or MRI
• Cardiac catheterization: Not routinely needed, but used when pulmonary hypertension needs quantification
• Goldman-Cecil Medicine, p. 985-986

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Management

Indications for Closure

• Qp/Qs ratio ≥ 1.5:1 with evidence of right heart volume overload
• Paradoxical embolism
• Symptomatic patients at any age

1. Catheter-Based (Device) Closure

• Adequate septal rim (≥5 mm on most borders)
• Suitable defect anatomy (secundum type)
• Defect diameter typically ≤38 mm

2. Surgical Closure (Open Heart Surgery)

• Primum and sinus venosus ASDs (not amenable to device closure)
• Inadequate septal rim for device anchorage
• Associated anomalies requiring surgical correction (anomalous pulmonary veins, AV valve repair)
• Failed device closure

• Direct suture closure - for small defects
• Patch closure - autologous pericardium or prosthetic material (Dacron/Gore-Tex) for larger defects

• Superior type: intracardiac patch baffle, or the Warden procedure (SVC translocation) when anomalous veins drain high
• Inferior type (scimitar syndrome): patch baffle in the IVC, potentially requiring hypothermic circulatory arrest
• Sabiston Textbook of Surgery, p. 2564-2397

3. Medical Management

• There is no medical therapy that closes the defect
• Antiplatelet therapy (aspirin) may be prescribed post-device closure for 3-6 months
• Rate/rhythm control and anticoagulation for atrial arrhythmias
• Diuretics and heart failure therapy if right heart failure is present

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Summary Table

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ATRIAL SEPTAL DEFECT (ASD)

Detailed MBBS Finals Exam Answer

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DEFINITION

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EMBRYOLOGY & CLASSIFICATION

1. The septum primum grows down as a crescent-shaped membrane to partition the atria; the anterior gap beneath it is the ostium primum (allows fetal right-to-left flow)
2. Before the ostium primum closes, perforations develop posteriorly forming the ostium secundum
3. A second ingrowth - the septum secundum - grows from the right side to cover the ostium secundum, leaving a residual channel: the foramen ovale
4. In fetal life, pulmonary pressure > systemic pressure, so the foramen ovale stays open (right-to-left)
5. At birth, lung expansion drops pulmonary vascular resistance (PVR), left atrial pressure exceeds right atrial pressure, and the foramen ovale closes

Types of ASD (Classified by Location)

• Harrison's Principles of Internal Medicine 22E, p. 2114; Robbins, p. 504

Exam tip: Primum ASD + mitral cleft + VSD = Atrioventricular Septal Defect (AVSD) / Endocardial cushion defect - seen in Down syndrome (trisomy 21).

Do NOT confuse ASD with Patent Foramen Ovale (PFO): PFO is persistence of the flap valve of the fossa ovalis without true septal deficiency. It causes no right heart dilation and is present in ~25% of adults. It is detected by bubble contrast echo (agitated saline) with Valsalva. - Harrison's, p. 2114

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PATHOPHYSIOLOGY

Direction of Shunt

Hemodynamic Consequences

Left atrium → (through ASD) → Right atrium
         ↓
  Increased RV volume load
         ↓
  Increased pulmonary blood flow (Qp/Qs may be 2-8x normal, up to >3:1)
         ↓
  Right heart dilation (RA + RV enlargement)
         ↓
  Dilated pulmonary artery trunk and branches

• Robbins, p. 505; Sabiston Textbook of Surgery, p. 2564

Progression over Time

Exam tip: Eisenmenger is less common in ASDs than in VSDs or PDAs because the lower-pressure atrial shunt causes less vascular trauma to pulmonary arterioles.

Paradoxical Embolism

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CLINICAL FEATURES

In Children

• Recurrent respiratory tract infections (due to increased pulmonary blood flow)
• Mild exercise intolerance

In Adults (symptoms typically emerge after the 3rd decade)

• Dyspnea on exertion (most common presenting symptom)
• Fatigue and reduced exercise tolerance
• Palpitations - from supraventricular arrhythmias (SVT, atrial flutter, AF)
• Syncope - from arrhythmias or reduced cardiac output
• Stroke - from paradoxical embolism or AF
• Signs of right heart failure in advanced disease: peripheral edema, elevated JVP, hepatomegaly

Physical Examination Findings

• Goldman-Cecil Medicine, p. 984; Braunwald's, p. 878

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INVESTIGATIONS

1. ECG

• Incomplete right bundle branch block (rSR' pattern in V1) - most characteristic finding
• Right axis deviation
• Right atrial enlargement (tall peaked P waves)
• Prolonged PR interval (1st degree heart block)
• Atrial fibrillation / flutter in older patients
• In primum ASD: left axis deviation (due to involvement of the AV node region)

Exam tip: Left axis deviation on ECG + ASD = Primum ASD (down syndrome link). Incomplete RBBB = Secundum ASD.

2. Chest X-Ray

• Pulmonary plethora - increased bilateral vascular markings (increased pulmonary blood flow)
• Dilated main pulmonary artery and its branches
• Right atrial and right ventricular enlargement
• Normal or small aortic knuckle (relatively reduced systemic flow)
• In Eisenmenger: oligaemic lung fields peripherally + dilated central pulmonary arteries ("pruning")

3. Echocardiography (Definitive Investigation)

• TTE (transthoracic echo): Identifies primum and secundum ASDs, measures defect size, shows right heart dilation. Doppler estimates Qp/Qs and pulmonary artery pressure
• TEE (transoesophageal echo): Required for sinus venosus ASDs (often missed on TTE) and for pre-procedural sizing before device closure. Also used intra-operatively during device deployment
• Bubble contrast echo (agitated saline): Detects right-to-left shunting (bubbles in LA/LV = positive); needed to detect PFO during Valsalva
• Findings: drop-out of interatrial septum signal, RV volume overload (RV dilation, paradoxical septal motion), LA-to-RA color Doppler jet

4. Cardiac MRI

• Excellent for sinus venosus defects, anomalous pulmonary venous anatomy, and pre-surgical planning
• Accurately quantifies Qp/Qs

5. Cardiac Catheterization

• Not routinely needed for diagnosis
• Indicated when: pulmonary hypertension suspected, conflicting echo results, pre-operative assessment of PVR
• Finding: step-up in oxygen saturation at the right atrial level (due to mixing of oxygenated left atrial blood)
• Qp/Qs calculated from oxygen saturations

6. Pulse Oximetry

• At rest and on exercise - to detect right-to-left shunting (desaturation) in patients with suspected Eisenmenger syndrome - Braunwald's, p. 878

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MANAGEMENT

General Principles

• Closure is recommended when Qp/Qs ≥ 1.5:1 with RV volume overload, regardless of symptoms
• Optimal timing: before school age (4-5 years); adult repair still beneficial if done before irreversible PH develops
• Contraindication to closure: Eisenmenger syndrome (fixed severe pulmonary hypertension with resting right-to-left shunt)

• 60% of ASD interventions worldwide are now catheter-based - Sabiston, p. 2565

1. Catheter-Based (Percutaneous) Device Closure

• Transfemoral venous access; catheter guided across the defect
• Amplatzer Septal Occluder (most widely used) - a self-centering, double-disc nitinol mesh device deployed under TEE + fluoroscopic guidance
• Device endothelialises within 3-6 months

• Atrial arrhythmias
• Complete heart block (rare)
• Device thrombus (aspirin prescribed for 3-6 months)
• Device erosion (~1 in 1000 cases) - can cause haemopericardium; any chest pain post-procedure warrants urgent echo - Braunwald's, p. 878-879

2. Surgical Closure (Open Heart Surgery)

• Primum ASD (always requires surgery; device not possible)
• Sinus venosus ASD (always requires surgery; cannot be catheter-closed)
• Coronary sinus defect
• Secundum ASD with inadequate rims for device anchorage
• Very large secundum defects
• Associated anomalies requiring surgical repair (AV valve repair, PAPVR repair)
• Failed or complicated device closure

1. General anaesthesia; median sternotomy (or right mini-thoracotomy for minimally invasive approach)
2. Cardiopulmonary bypass established (aortic + venous cannulation)
3. Aortic cross-clamp + cardioplegia for myocardial protection
4. Right atriotomy - direct visualisation of the defect
5. Closure:
   • Direct suture closure - for small defects (primary closure with continuous suture)
   • Patch closure - autologous pericardium or synthetic patch (Dacron / Gore-Tex) for larger defects
6. De-airing of the left atrium before closure
7. Termination of bypass; closure

• Intracardiac patch baffle redirecting anomalous pulmonary veins to LA
• Warden procedure: SVC is divided, the cardiac end oversewn, and the cephalic SVC end is anastomosed to the right atrial appendage; a patch baffles the anomalous veins to the LA

• Complex repair; may require patch baffle within the intrahepatic IVC
• May need hypothermic circulatory arrest - Sabiston, p. 2396

• Atrial arrhythmias may persist (especially AF) - surgery does not reliably reduce arrhythmia burden in older adults - Braunwald's, p. 878
• Follow-up TTE at 1 week, 1 month, then annually for at least 5 years (device closure)
• Patients with elevated PVR at closure need ongoing monitoring as PAH can progress

3. Medical Management

• No pharmacological therapy closes the defect
• Antiplatelet therapy (aspirin 75-150 mg/day) for 3-6 months post-device closure (prophylaxis against device thrombus)
• Rate/rhythm control + anticoagulation (warfarin or NOAC) for atrial fibrillation
• Diuretics + ACE inhibitors for right heart failure symptoms
• Pulmonary arterial hypertension (PAH) therapy (e.g., sildenafil, bosentan, prostacyclins) for Eisenmenger syndrome - treats symptoms but does not reverse the shunt
• Endocarditis prophylaxis: NOT routinely required for isolated secundum ASD (low risk); required for 6 months post-device/surgical repair

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COMPLICATIONS OF UNTREATED ASD

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QUICK COMPARISON: ASD vs PFO

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SUMMARY - KEY EXAM POINTS

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CONGENITAL HEART DEFECTS REQUIRING OPEN HEART SURGERY

Detailed MBBS Finals Exam Answers

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1. VENTRICULAR SEPTAL DEFECT (VSD)

Definition

Classification (by Location)

Pathophysiology

• Small (restrictive) VSDs: Offer high resistance to flow; RV pressure remains normal or near-normal; Qp/Qs rarely exceeds 1.5. The high-velocity jet of blood creates turbulence but causes no significant volume overload. Risk: endocarditis from endocardial damage.
• Large (non-restrictive) VSDs: Equalize LV and RV pressures; Qp/Qs can be very high. Causes massive pulmonary overcirculation and LV volume overload. If untreated, sustained high pulmonary blood flow causes pulmonary vascular remodeling, rising PVR, and ultimately Eisenmenger syndrome (shunt reversal to R→L, cyanosis). VSDs carry a higher risk of Eisenmenger than ASDs.
• Schwartz's Surgery, p. 814-815

Exam tip: ~50% of small/moderate muscular VSDs close spontaneously in the first 2 years of life. Perimembranous VSDs also may close but less often. Outlet VSDs virtually never close spontaneously.

Clinical Presentation

Symptoms

• Small VSD: Asymptomatic (discovered incidentally on auscultation)
• Large VSD: In infancy - congestive heart failure (tachypnoea, poor feeding, failure to thrive, recurrent chest infections, diaphoresis with feeding); exercise intolerance; growth retardation

Signs

Exam tip: A very small VSD makes a loud murmur (high-velocity jet, maladie de Roger). A very large VSD may make a softer murmur (pressures equalize, less turbulence) but causes heart failure.

Investigations

• ECG: Left ventricular hypertrophy (or biventricular in large shunts); left atrial enlargement
• CXR: Cardiomegaly; pulmonary plethora (increased vascular markings); enlarged LA, LV; dilated pulmonary artery
• Echocardiography (TTE): Definitive - shows defect, measures shunt, estimates PA pressure
• Cardiac catheterisation: Step-up in O2 saturation at right ventricular level; used to measure PVR when Eisenmenger is suspected

Management

Indications for Closure

• Qp/Qs ≥ 2:1 with symptoms or evidence of LV volume overload
• Any VSD causing heart failure, failure to thrive
• Outlet VSDs (risk of aortic regurgitation from valve prolapse)
• History of infective endocarditis
• Contraindication: Eisenmenger syndrome (fixed PVR; closure would acutely right-heart overload)

1. Surgical Closure (Primary treatment)

• Cardiopulmonary bypass, right ventriculotomy or right atriotomy (preferred - avoids RV incision)
• Patch closure with Dacron or autologous pericardium using interrupted pledgeted sutures (Fig. 20-60 - intraoperative interrupted suture technique)
• Device (catheter-based) closure: available for selected muscular and perimembranous VSDs in centres with expertise
• Pulmonary artery banding: Palliative procedure to reduce pulmonary blood flow in small infants not suitable for primary repair; debanded when definitive repair is done

2. Medical (pre-operative)

• Diuretics (furosemide), ACE inhibitors (captopril) for heart failure
• High-calorie feeds / nasogastric feeding for growth failure
• Endocarditis prophylaxis

Outcomes

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2. TETRALOGY OF FALLOT (TOF)

Definition

The Four Features (Mnemonic: PROVE)

1. Pulmonary stenosis (RVOT obstruction - subvalvular infundibular stenosis ± valvular stenosis ± PA hypoplasia)
2. Right ventricular hypertrophy (secondary to RVOT obstruction)
3. Overriding aorta (aorta straddles the VSD, receiving blood from both ventricles)
4. VSD (large, perimembranous, non-restrictive - the only "hole")

"Monology of Fallot" - Van Praagh: all four features result from the single malalignment of the infundibular septum. - Schwartz's Surgery, p. 812

Pathophysiology

RVOT obstruction → RV pressure rises
↓
Blood preferentially shunts RIGHT-TO-LEFT through VSD (deoxygenated blood → aorta)
↓
Desaturated blood enters systemic circulation → CYANOSIS
↓
Decreased pulmonary blood flow → Less oxygen exchange → Worsening hypoxaemia
↓
Polycythaemia (compensatory) → Thrombotic risk

• If RVOT obstruction is mild: shunt may be L→R initially (acyanotic or "pink TOF")
• If RVOT obstruction is severe: dominant R→L shunt, early cyanosis
• Heart is enlarged, "boot-shaped" (coeur en sabot) on CXR due to RVH + concave pulmonary bay
• The proximal aorta is dilated; pulmonary trunk is hypoplastic
• In severe cases (pulmonary atresia): PDA or bronchial collaterals are the only source of pulmonary blood flow
• Robbins, p. 288-290

Clinical Presentation

Symptoms

• Cyanosis - present at birth or develops in first months of life
• Clubbing of fingers and toes (chronic hypoxaemia)
• Polycythaemia (compensatory erythropoiesis)
• Squatting - characteristic posture in children after exertion; squatting increases SVR (compresses femoral arteries), decreasing R→L shunt and temporarily improving saturation
• Failure to thrive, exercise intolerance

Tet Spells (Hypercyanotic Episodes)

• Sudden infundibular spasm → acute decrease in pulmonary blood flow → severe hypoxaemia → crying/agitation → further spasm → vicious cycle
• Triggers: Crying, feeding, defecation, fever, tachycardia
• Features: Sudden deepening cyanosis, hyperpnoea, limpness, syncope, possible seizure/death

1. Knee-chest position (simulates squatting - increases SVR)
2. Oxygen (100%)
3. Morphine (0.1 mg/kg IV/SC) - reduces infundibular spasm, decreases tachycardia
4. IV fluid bolus (increases preload)
5. IV propranolol - reduces RVOT spasm
6. IV phenylephrine - increases SVR, reduces R→L shunt
7. Sodium bicarbonate if metabolic acidosis
8. Urgent surgical repair if spells are refractory

Physical Signs

Exam tip: In TOF the murmur comes from the pulmonary stenosis, not the VSD. The louder the murmur, the less severe the TOF (more blood going through the RVOT). A quiet murmur = very severe obstruction = worse cyanosis.

Investigations

• ECG: Right axis deviation; right ventricular hypertrophy (tall R in V1, deep S in V5-V6)
• CXR: Boot-shaped heart (coeur en sabot) - RVH + upturned apex; decreased pulmonary vascular markings; right aortic arch in 25%
• Echocardiography: Definitive diagnosis; defines RVOT anatomy, VSD position, coronary origins, PA size
• Cardiac catheterisation: Rarely needed; can precipitate a tet spell; reserved for defining coronary anatomy or PA size if echo inconclusive
• MRI: Used in repaired TOF follow-up to quantify pulmonary regurgitation and RV volumes

Management

Pre-operative palliation

• Beta-blockers (propranolol) to reduce frequency of tet spells
• Modified Blalock-Taussig (BT) shunt: In small neonates not suitable for primary repair - subclavian artery to ipsilateral pulmonary artery (via Gore-Tex graft), increasing pulmonary blood flow; staged approach to definitive repair

Definitive Surgical Repair (Intracardiac repair)

1. VSD closure: Patch placed through right atrium (or right ventriculotomy), directing LV outflow to aorta
2. RVOT relief: Resection of infundibular muscle; pulmonary valvotomy; transannular patch (pericardium or synthetic) if pulmonary annulus is hypoplastic
3. Pulmonary artery reconstruction if necessary

Long-term Follow-up After Repair

• Pulmonary regurgitation - progressive RV dilation → RV failure → need pulmonary valve replacement (surgical or transcatheter Melody valve)
• Residual RVOT obstruction
• Ventricular arrhythmias (VT) - from RV fibrosis at ventriculotomy scar; risk of sudden cardiac death
• Right bundle branch block (RBBB) - common post-repair
• QRS duration >180ms on ECG = risk factor for VT and sudden death

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3. DOUBLE OUTLET RIGHT VENTRICLE (DORV)

Definition

Classification (by VSD Position)

Pathophysiology

1. Size and location of VSD relative to great vessels
2. Presence or absence of RVOT (pulmonary stenosis) obstruction
3. Associated anomalies (arch hypoplasia, coarctation)

• Subaortic VSD without PS → pulmonary overcirculation, CHF (like large VSD)
• Subaortic VSD + PS → cyanosis (like TOF)
• Subpulmonic VSD (Taussig-Bing) → oxygenated LV blood streams into pulmonary artery; deoxygenated RV blood into aorta → cyanosis (like TGA)

Clinical Presentation

1. Pulmonary overcirculation/CHF (subaortic or doubly committed VSD without PS) - presents in infancy with tachypnoea, failure to thrive, recurrent infections
2. Cyanosis (subaortic VSD + PS) - resembles TOF
3. Cyanosis with CHF (Taussig-Bing / subpulmonic VSD) - resembles TGA

Management

• Rastelli procedure: Intraventricular LV-to-aorta tunnel + RV-to-PA conduit (for VSD + PS cases)
• Arterial Switch Operation (ASO): For Taussig-Bing anatomy
• Palliative PA banding: If complex anatomy defers definitive repair

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4. TRANSPOSITION OF THE GREAT ARTERIES (TGA / D-TGA)

Definition

Exam tip - Concordance rules:

• TGA (D-TGA): AV concordant (RA→RV, LA→LV) + VA discordant (RV→Ao, LV→PA) = Complete TGA
• Congenitally Corrected TGA (ccTGA): AV discordant + VA discordant = physiologically corrected but with morphologic RV as systemic pump

Embryology

Pathophysiology

Systemic venous (deoxygenated) blood:
IVC/SVC → RA → RV → AORTA → systemic circulation → (never reaches lungs)

Pulmonary venous (oxygenated) blood:
Pulmonary veins → LA → LV → PULMONARY ARTERY → lungs → (never reaches systemic circulation)

• ASD / patent foramen ovale
• VSD (present in ~30% of cases - "TGA-VSD")
• PDA (patent ductus arteriosus)

• Robbins, p. 320-322; Sabiston, p. 2575

Variants

• TGA-IVS (intact ventricular septum): Most common (~65%); presents with profound cyanosis at birth when PDA closes
• TGA-VSD (~35%): Sufficient mixing via VSD; may present with less cyanosis but with pulmonary overcirculation and CHF
• TGA-VSD with PS: Reduced pulmonary blood flow + cyanosis

Clinical Presentation

Symptoms

• Severe central cyanosis from birth (in TGA-IVS) - does NOT respond to oxygen administration (pathognomonic)
• Tachypnoea without respiratory distress (the "happy but blue" neonate)
• Metabolic acidosis from tissue hypoxia
• RV hypertrophy (RV acts as systemic ventricle): LV is small/hypoplastic (low-pressure pulmonary circuit)

Physical Signs

Investigations

• CXR: Classic "egg on a string" (egg-shaped heart with narrow superior mediastinum due to parallel great vessels lying on top of each other, no thymic shadow); increased pulmonary vascular markings
• ECG: Right axis deviation; RVH
• Echocardiography: Definitive - shows AV concordance, VA discordance, coronary origins, VSD, size of LA/LV (important for ASO planning)
• Arterial blood gas: Profound hypoxaemia with metabolic acidosis; hyperoxia test - PaO2 fails to rise above ~150 mmHg on 100% O2 (unlike respiratory causes)

Management - This is a Neonatal Emergency

Immediate Stabilisation

1. IV Prostaglandin E1 (PGE1) - maintains/reopens the ductus arteriosus, allowing mixing and improving systemic saturation (first-line emergency treatment)
2. Balloon Atrial Septostomy (Rashkind procedure) - a balloon catheter is passed via the femoral/umbilical vein across the foramen ovale; the balloon is inflated in the LA and forcefully withdrawn to tear the atrial septum, creating an open ASD to allow atrial-level mixing (Fig. 113.27). Achieves SaO2 of 70-80%, buying time for definitive surgery
3. Metabolic correction (bicarbonate if acidotic)

Definitive Surgery - Arterial Switch Operation (ASO / Jatene procedure)

1. Cardiopulmonary bypass + deep hypothermic circulatory arrest (neonates)
2. Transect both great vessels above the sinuses of Valsalva
3. Excise coronary arteries with buttons of aortic wall from the aortic root (now neoaortic/pulmonary root)
4. Lecompte maneuver: The distal pulmonary artery bifurcation is brought anterior to the reconstructed neoaorta to prevent compression
5. Coronary reimplantation into the pulmonary root (now neoaorta) - the most technically challenging step
6. Distal aorta anastomosed to neoaorta (the original pulmonary root)
7. Distal pulmonary artery (neopulmonary artery) anastomosed to what was the aortic root
8. Pericardial patches to reconstruct the donor coronary sites on the original aorta (now neopulmonary artery)
9. VSD closure (if present) via right atrium

• Neopulmonary artery stenosis (most common - at anastomotic sites)
• Coronary artery complications (kinking, stenosis, occlusion)
• Neoaortic valve insufficiency
• Excellent overall survival: >95% at 20 years in experienced centres

Historical (now obsolete): Atrial Switch Operations

• Mustard procedure (pericardial baffle) and Senning procedure (native atrial tissue baffle): Redirected systemic venous return to LV→PA and pulmonary venous return to RV→Ao = physiologic but not anatomic correction
• Problem: The morphologic RV remained the systemic ventricle and failed progressively → systemic RV failure, baffle obstruction/leaks, atrial arrhythmias
• Still seen in adults who were repaired before the ASO era

Congenitally Corrected TGA (ccTGA)

• Both AV and VA connections discordant: RA→morphologic LV→PA and LA→morphologic RV→Ao
• Physiologically corrected but RV acts as systemic ventricle
• May be asymptomatic for decades; progressive systemic RV failure; high incidence of complete heart block
• Surgical option: Double switch (atrial switch + ASO) to make morphologic LV the systemic ventricle; requires prior LV retraining if LV has been decompressed - Sabiston, p. 2578-2780

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5. ATRIOVENTRICULAR CANAL DEFECT (AV CANAL / AVSD)

Definition

• Deficiency of the atrial septum (primum ASD)
• Deficiency of the ventricular septum (inlet VSD)
• Abnormal AV valves (single common AV valve or cleft mitral valve)

Key association: ~60-70% of complete AVSDs occur in patients with Trisomy 21 (Down syndrome). AVSD is the most common cardiac defect in Down syndrome.

Classification

• Type A (most common): Superior bridging leaflet committed to LV side; chordae attach to crest of VSD
• Type B: Bridging leaflet chordae attach to an anomalous papillary muscle in RV (straddling)
• Type C: "Free-floating" superior bridging leaflet; no chordal attachment to septum

Pathophysiology

Primum ASD → L→R atrial shunt
+
Inlet VSD → L→R ventricular shunt (large, non-restrictive)
+
Common AV valve regurgitation → volume overload of both atria and ventricles
= Massive pulmonary overcirculation + biventricular volume overload
= CHF in infancy + early development of pulmonary vascular disease

• AV node and bundle of His are displaced inferiorly to the rim of the primum ASD and along the inferior edge of the VSD - must be protected during repair to avoid complete heart block
• "Goose-neck" deformity of LVOT on angiography - elongated LV outflow tract due to anterior displacement of the aortic valve
• Risk of early Eisenmenger syndrome (especially in Down syndrome patients, who have particularly reactive pulmonary vasculature)

Clinical Presentation

Partial AVSD

• May be asymptomatic until adulthood (behaves like an ASD with mitral regurgitation)
• Exercise intolerance, dyspnoea
• Signs: wide fixed S2 splitting + pansystolic murmur of MR (left axillary radiation)
• Left axis deviation on ECG is characteristic (due to displacement of conduction system)

Complete AVSD

• Presents in infancy (2-6 weeks) with:
  • Congestive heart failure: tachypnoea, poor feeding, diaphoresis, failure to thrive
  • Recurrent respiratory infections
  • Cardiomegaly
• Physical signs: tachycardia, gallop rhythm, hepatomegaly, pansystolic murmur (MR/TR and VSD), wide fixed S2 splitting

Physical Signs Summary

Investigations

• ECG: Left axis deviation (characteristic - due to posteriorly displaced conduction system); superior QRS axis; incomplete RBBB; biventricular hypertrophy; prolonged PR interval
• CXR: Cardiomegaly; pulmonary plethora; dilated main pulmonary artery
• Echocardiography: Definitive - shows primum ASD, inlet VSD, common AV valve, valve regurgitation, Rastelli type, ventricular balance, PA pressure
• Cardiac catheterisation: In older patients to assess PVR (step-up at both RA and RV level)
• Karyotype/genetic testing: Given high association with Down syndrome (trisomy 21)

Exam tip - ECG axis: Partial AVSD = left axis deviation. Complete AVSD = superior axis (extreme left axis). This contrasts with secundum ASD (right axis deviation). Left axis deviation in a child with a murmur = think AVSD.

Management

Timing

• Complete AVSD: Surgical repair recommended by 3-6 months of age (before irreversible pulmonary vascular disease develops; Down syndrome patients may need even earlier repair due to more reactive pulmonary vasculature)
• Partial AVSD: May be deferred to 2-4 years of age if hemodynamically stable

Medical (Pre-operative)

• Diuretics, ACE inhibitors for CHF
• High-calorie feeds / NG feeds for growth
• Pulmonary vasodilators if pulmonary hypertension present

Surgical Repair - Open Heart Surgery

1. Close primum ASD
2. Close inlet VSD
3. Divide common AV valve into two separate (left and right) competent valves
4. Protect the displaced AV node and bundle of His to avoid complete heart block

• Single-patch technique: One large patch used to close both ASD and VSD; common AV valve sutured to the patch
• Two-patch technique (preferred): Separate patches for the VSD (pericardial or Dacron) and ASD; AV valve divided and sutured to patches independently. Preserves more AV valve tissue and is associated with better valve function - Sabiston, p. 2567

Post-operative Considerations

• Pulmonary hypertensive crisis - may occur in the early post-operative period (ICU management: oxygen, hyperventilation, sedation, inhaled nitric oxide)
• Long-term risk: recurrent left AV valve regurgitation (most common reason for re-operation), LVOT obstruction (goose-neck deformity), arrhythmias, heart block

Outcomes

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MASTER COMPARISON TABLE

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Quick Navigation

• VSD: loudest murmur in small defects (maladie de Roger)
• TOF: murmur from RVOT stenosis, NOT the VSD; squatting relieves tet spells
• DORV: Taussig-Bing (subpulmonic VSD) is physiologically TGA
• TGA: the only condition where cyanosis does NOT respond to oxygen; single loud S2; egg-on-a-string CXR
• AVSD: left/superior axis deviation on ECG + Down syndrome = pathognomonic combination

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CONGENITAL HEART DEFECTS: SURGICAL MANAGEMENT

Surgery-Focused MBBS Finals Exam Answer

For each condition the answer is structured: Brief recap → Surgical indications → Pre-operative preparation → Operative steps (detailed) → Post-operative issues & outcomes

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1. VENTRICULAR SEPTAL DEFECT (VSD)

Brief Recap

Indications for Surgical Closure

~50% of small muscular VSDs close spontaneously by age 2 and may be observed. Perimembranous may also decrease in size. Outlet VSDs never close spontaneously.

Pre-operative Preparation

• Optimise nutritional status (high-calorie feeds / NG feeding)
• Diuretics (furosemide) + ACE inhibitors (captopril) for heart failure
• Echocardiography to define anatomy; cardiac catheterisation only if PVR measurement needed
• Pulmonary artery banding (PA band): Palliative option for tiny infants (<2 kg) with complex or multiple (Swiss-cheese) VSDs not amenable to primary repair. A band is placed around the main PA to restrict pulmonary blood flow and prevent vascular disease. The band is removed when the child is taken for definitive repair.

Surgical Technique

Setup

• General anaesthesia with arterial line, central venous access
• Median sternotomy
• Cardiopulmonary bypass (CPB) established: aortic and bicaval venous cannulation (separate SVC and IVC cannulae to allow right heart work without flooding the field)
• Moderate hypothermia (28-32°C) and cold cardioplegic arrest (antegrade, into aortic root)

Approach

• Right atriotomy - preferred for most perimembranous, inlet, and many muscular VSDs. The tricuspid valve leaflets are retracted to expose the VSD through the right atrium.
• Right ventriculotomy - for apical muscular VSDs and certain complex cases (produces RV scar, so avoided if possible)
• Pulmonary arteriotomy or infundibular RV incision - for supracristal/outlet VSDs

Closure

• VSD is inspected carefully; relationship to the tricuspid valve, aortic valve, and His bundle noted
• Patch closure is standard for all but the smallest defects:
  • Dacron (polyester) or Gore-Tex (PTFE) synthetic patch, or
  • Autologous pericardium (treated with glutaraldehyde to stiffen it)
• Patch is sutured with interrupted pledgeted sutures or running suture technique (interrupted preferred near conduction tissue - allows sutures to loosen if oedema causes tension post-op)

Critical Anatomic Hazard: The Conduction System

• For the anterosuperior rim: sutures can safely be placed on the septum
• For the posteroinferior rim: sutures placed 3-5 mm away from the rim into RV myocardium

Supracristal VSD (special case)

Swiss-cheese (multiple muscular) VSDs

• Very challenging: some advocate PA banding in infancy + staged closure later
• Modern techniques: oversized patch, fibrin glue, combined intraoperative device closure (Amplatzer muscular VSD occluder) deployed through a purse-string in the RV with echocardiographic guidance, transatrial repair techniques

Percutaneous Device Closure

• Amplatzer Muscular VSD Occluder: for muscular VSDs
• Amplatzer Membranous VSD Occluder: for perimembranous VSDs - risk of heart block because the device sits adjacent to the His bundle; less commonly used than for muscular VSDs
• Also used for residual VSDs after surgery, and per-ventricular (hybrid) approach via mini-sternotomy

Post-operative Considerations & Outcomes

• Schwartz's Principles of Surgery, p. 814-816; Sabiston Textbook of Surgery, p. 2566

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2. TETRALOGY OF FALLOT (TOF)

Brief Recap

Indications for Surgery

• Primary intracardiac repair at 3-6 months of age (standard current approach at most centres)
• Neonatal repair if profound cyanosis or severe desaturation
• Staged approach (palliative shunt first, then repair) in:
  • Neonates <3 months who are haemodynamically unstable
  • Requirement for an extracardiac conduit (due to anomalous LAD crossing RVOT)
  • Severe branch PA hypoplasia (shunt promotes PA growth before repair)
  • Associated major aortopulmonary collaterals (MAPCAs) - unifocalisation surgery needed

Pre-operative Preparation

1. Echocardiography - define RVOT anatomy, VSD, PA size, branch PA anatomy, coronary origins
2. CT/MRI angiography - PA anatomy, aortic arch, coronary origins if anomalous
3. Cardiac catheterisation - rarely needed; can precipitate tet spell (RVOT spasm); used only if coronary anatomy unclear
4. Beta-blockers (propranolol) - reduce tet spells pre-operatively
5. PGE1 - in severe neonatal cases to maintain ductal patency and pulmonary blood flow

Palliative Shunts (Staged Approach)

• Right thoracotomy; right subclavian artery divided and end-to-side anastomosis to right pulmonary artery (RPA)
• No longer performed routinely (sacrifices the subclavian artery)

• Right or left thoracotomy (or median sternotomy)
• A Gore-Tex tube graft (3.5-4 mm in neonates) is interposed between the subclavian artery and ipsilateral pulmonary artery - the subclavian is not divided
• Increases pulmonary blood flow, improves oxygenation, promotes PA growth

Definitive Surgical Repair - Intracardiac Repair

Setup

• General anaesthesia; median sternotomy
• Cardiopulmonary bypass (aortic + bicaval cannulation)
• Moderate hypothermia (28-30°C) + antegrade cardioplegia (cold crystalloid or blood)
• All prior BT shunts and the ductus arteriosus are ligated and divided before going on bypass

Step-by-Step Repair

• Transatrial approach (modern preferred): Right atriotomy → retract tricuspid leaflets → visualise VSD and infundibular muscle from inside the right atrium; no RV incision needed for most cases
• Right ventriculotomy: Traditional approach; still used when diffuse RVOT hypoplasia requires extensive muscle resection or a transannular patch

• Pulmonary valve examined: commissurotomy if leaflets are fused (valvular PS)
• If the pulmonary annulus is adequate (Z-score ≥ -2 to -2.5; PA/Ao ratio ≥ 0.5): RVOT patching stays above the annulus (annulus preserved)
• If annulus is hypoplastic (Z-score < -2.5; RV/LV pressure ratio predicted >0.7): Transannular patch is required

• A longitudinal incision is extended from the RVOT across the pulmonary annulus into the main PA
• A pericardial or synthetic patch is sutured to widen the entire RVOT-annulus-main PA segment
• Provides excellent RVOT relief but destroys pulmonary valve competence → creates free pulmonary regurgitation - the main late complication requiring re-intervention

• A Dacron or pericardial patch is placed to close the large perimembranous malalignment VSD
• The patch redirects LV outflow to the aorta
• Critical: Sutures along the posteroinferior rim are placed in the RV myocardium (not the septal crest) to avoid injuring the right bundle branch and bundle of His
• The aortic override is corrected by appropriate patch placement - the aorta is committed to the LV

• Hegar dilators used to assess pulmonary annulus size intraoperatively
• Intraoperative TEE before closure of bypass: assess for residual VSD, adequacy of RVOT relief, RV and LV function
• Direct pressure measurement: RV/LV systolic pressure ratio after repair should be <0.7; if >0.85, further RVOT work required

Special Surgical Scenarios

• The LAD crosses the anterior RVOT - a transannular patch will divide it
• Solution: Use a right ventricle-to-pulmonary artery (RV-PA) conduit (Hancock, Contegra, or homograft), which bypasses the anomalous artery by connecting RV to distal main PA via an extracardiac conduit

• Major aortopulmonary collateral arteries supply distal lung segments
• Unifocalisation surgery: All collaterals are surgically disconnected from the aorta and connected together ("unifocalised") into a single pulmonary blood supply
• Then intracardiac repair + RV-PA conduit

Post-operative Issues & Outcomes

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3. DOUBLE OUTLET RIGHT VENTRICLE (DORV)

Brief Recap

Surgical Goal

Pre-operative Planning

• Echocardiography: VSD position relative to great vessels, PA anatomy, coronary anatomy, tricuspid-to-pulmonary valve distance
• MRI/CT: Great vessel relationships, arch anatomy, coronary origins
• Cardiac catheterisation: In older infants to measure PVR if pulmonary overcirculation has been longstanding

Surgical Approaches (by VSD Type)

A. Subaortic VSD (± PS) - TOF Type (47%)

• Intraventricular baffle (tunnel repair): A patch tunnel is constructed inside the RV, committing the LV through the VSD to the aorta. The VSD may need to be enlarged anterosuperiorly (away from the conduction system, which lies posteroinferiorly). No RV-PA conduit required if PA is unobstructed.

• Intraventricular LV-to-aorta tunnel patch + RVOT reconstruction (infundibular resection ± transannular patch ± RV-PA conduit)
• Essentially the same as TOF repair with VSD-to-aorta baffling

B. Doubly Committed VSD (4%)

• LV-to-aorta intraventricular tunnel; PA must be deobstructed if any obstruction present

C. Non-committed (Remote) VSD (26%) - Most Complex

• Intraventricular tunnel from VSD to aorta + closure of PA + RV-to-PA extracardiac valved conduit (Rastelli-type)
• VSD may need enlargement anterosuperiorly
• If complex anatomy precludes biventricular repair: single-ventricle palliation pathway (Norwood → Glenn → Fontan)
• In infants without PS: PA banding first (to control pulmonary overcirculation and prevent Eisenmenger) → delayed repair at 2-3 years (allows larger conduit placement, reducing future re-operations)

D. Subpulmonic VSD / Taussig-Bing Anomaly (23%) - TGA Type

• Immediate neonatal management: Balloon atrial septostomy (Rashkind) if cyanosis severe (same as TGA)
• PGE1 to maintain ductal patency
• Definitive repair: Arterial Switch Operation (ASO) + VSD closure (the subpulmonary VSD allows LV blood to enter the PA which is switched to become the aorta; the ASO creates ventriculoarterial concordance)

• Rastelli procedure: Intraventricular tunnel baffles LV through VSD to aorta; RV-PA conduit placed
• Alternative: REV procedure (Réparation à l'Étage Ventriculaire): Resects muscular conus between aorta and PA roots; LV-to-aorta baffle; direct translocation of main PA to RV (Lecompte maneuver) without conduit - reduces future conduit revisions
• Alternative: Yasui procedure: Damus-Kaye-Stansel (DKS) anastomosis of PA to aorta + LV-to-PA baffle via VSD + RV-PA conduit

Post-operative Issues & Outcomes

• Reintervention needed in ~37% at 15 years - mainly conduit replacement and RVOT reconstruction
• Complex repairs (Taussig-Bing, non-committed VSD) carry higher morbidity/mortality than subaortic type
• Arterial Switch for Taussig-Bing: associated with higher early mortality than Rastelli but reduces risk of late death
• Non-committed VSD with hypoplastic LV structures: single-ventricle palliation pathway offers better outcomes than attempted biventricular repair
• Schwartz's Surgery, p. 812-813; Sabiston, p. 2752

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4. TRANSPOSITION OF THE GREAT ARTERIES (D-TGA)

Brief Recap

Emergency Pre-operative Management

• Reopens/maintains the ductus arteriosus → establishes L→R (pulmonary-to-systemic) mixing via the duct → improves arterial saturation
• First-line immediate therapy for any suspected ductal-dependent cyanotic CHD in a neonate
• Dose: 0.05-0.1 mcg/kg/min IV
• Side effects: apnoea, hypotension, fever - have airway ready

• Creates an atrial-level communication to allow mixing between the two parallel circuits
• Performed in the catheterisation lab or at the bedside under echocardiographic guidance
• A balloon catheter (Rashkind catheter) is passed via femoral or umbilical vein → IVC → RA → across the foramen ovale into the LA
• Balloon inflated with dilute contrast, then forcefully pulled back across the atrial septum, tearing the fossa ovalis to create a large unobstructed secundum ASD
• Achieves SaO2 70-80%, allowing weaning from PGE1 and stabilisation before definitive surgery

Timing of Definitive Surgery

• TGA-IVS (intact ventricular septum): ASO within first 2-3 weeks of life - before the LV involutes from its low-pressure pulmonary work and loses capacity to support systemic circulation
• TGA-VSD: Can extend slightly longer (VSD provides mixing); still operated in first 4-6 weeks
• Delayed LV (>3-4 weeks in TGA-IVS): LV wall becomes thin and compliant. To perform ASO, the LV must first be retrained: pulmonary artery banding + BT shunt → artificially raises LV pressure → LV hypertrophies over 1-2 weeks → ASO then performed

Definitive Surgery: Arterial Switch Operation (Jatene, 1975)

Setup

• General anaesthesia; median sternotomy
• Cardiopulmonary bypass (aortic + bicaval cannulation)
• Deep hypothermic circulatory arrest (DHCA) at 18-20°C - often used in neonates, particularly during coronary transfer where temporary circulatory arrest provides a bloodless field
• Profound cold cardioplegia

Step-by-Step ASO

• The coronary ostia are excised from the original aortic root (which will become the neopulmonary artery) with a generous "button" of aortic wall (trapdoor technique)
• The coronary buttons are reimplanted into the original pulmonary root (which becomes the neoaorta)
• There are five basic coronary configurations (Yacoub-Radley-Smith classification A-E); all are technically achievable but some (intramural coronaries, single ostium) require special techniques

• The distal pulmonary artery bifurcation is pulled anteriorly (brought in front of the newly reconstructed aorta)
• This places the PA branches anterior to the aorta, reducing tension on the anastomoses and preventing compression of the translocated coronary arteries by the reconstructed great vessels

• The distal aorta is anastomosed to the original pulmonary root (neoaorta) - this is now the LV outflow, carrying oxygenated blood to the systemic circulation
• The distal pulmonary artery (which now lies anterior to the aorta after Lecompte) is anastomosed to the original aortic root (neopulmonary artery) - this is now the RV outflow

• The holes left in the original aortic root (now neopulmonary artery) from coronary excision are reconstructed with separate pericardial patches to create a smooth neopulmonary artery

Special Surgical Scenarios

TGA-VSD with Pulmonary Stenosis (LVOTO)

• Mild LVOTO: ASO + LVOT resection + VSD closure
• Severe PS or pulmonary atresia:
  • Rastelli procedure: Intraventricular patch baffles LV through VSD to aorta; RV connected to distal PA via valved extracardiac conduit (homograft or porcine)
  • REV procedure: LV-to-aorta baffle + PA directly translocated to RV (Lecompte manoeuvre) without conduit
  • Aortic root translocation (Nikaidoh procedure): Entire aortic root with coronaries translocated posteriorly to sit over the LV outflow; VSD closed; RV-PA reconstruction

Atrial Switch Operations (Historical - Mustard & Senning)

• Systemic RV failure (dilated, reduced EF)
• Tricuspid (systemic AV valve) regurgitation
• Baffle obstruction (SVC or IVC limb)
• Baffle leaks
• Atrial arrhythmias (sick sinus syndrome, AF/flutter)
• Sudden cardiac death

Post-operative Issues & Outcomes (ASO)

• Sabiston, p. 2575-2577

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5. ATRIOVENTRICULAR CANAL DEFECT (AVSD)

Brief Recap

Classification for Surgery (Rastelli)

Indications for Surgery

• Complete AVSD: Repair by 3-6 months of age - before irreversible pulmonary vascular disease
• Down syndrome patients: Even earlier (more reactive pulmonary vasculature; PH develops faster)
• Partial AVSD: Can be deferred to 2-4 years if haemodynamically stable; earlier if MR is severe
• Unbalanced AVSD (one ventricle dominant): Single-ventricle palliation if biventricular repair not feasible
• AVSD + TOF: Repair both simultaneously; more complex; may need RVOT reconstruction in addition

Pre-operative Preparation

• Echocardiography: Rastelli type, AV valve morphology, degree of regurgitation, ventricular balance, PA pressure
• Diuretics, ACE inhibitors for CHF
• Nutritional optimisation
• Cardiac catheterisation if PVR needs quantification in older patients
• Karyotype (Down syndrome confirmation)
• Pulmonary artery banding: Rarely used now; only if <2 months and too small for repair, or in complex unbalanced cases

Definitive Surgical Repair

Setup

• General anaesthesia; median sternotomy
• Cardiopulmonary bypass (aortic + bicaval venous cannulation - bicaval allows complete right heart decompression and working in a dry field)
• Moderate hypothermia + cold cardioplegia

Access

• The primum ASD is visible in the floor of the right atrium
• The common AV valve orifice is visible
• The inlet VSD (if complete) is visible through the AV valve

Key Surgical Steps

• The superior bridging leaflet (SBL) is divided at the line of the interventricular septum to create a left AV valve and a right AV valve
• In Rastelli Type A: the chordal attachments to the septum are used as a guide for division; the SBL is divided at its midpoint
• In Rastelli Type C: the free-floating leaflet must be divided carefully and additional artificial chordae may be required

• The cleft in the anterior leaflet of the left AV valve (between the divided superior and inferior bridging leaflet components) is closed with interrupted sutures
• Care must be taken not to overcorrect and create valve stenosis (the cleft also contributes to valve surface area)
• The valve is tested with saline injection for competence before patch placement

• A separate ventricular patch (autologous pericardium or Dacron) is placed to close the inlet VSD
• The patch is sutured to the crest of the ventricular septum and posteriorly along the floor of the right ventricle
• CRITICAL: The AV node lies at the posteroinferior angle of the primum ASD (between the ASD, VSD, and coronary sinus). The His bundle runs posteroinferiorly along the inferior rim of the VSD. All sutures in this zone must be placed on the right side of the ventricular septum - never through it - to avoid complete heart block

• The divided leaflet tissue (left and right) is sutured to the superior rim of the ventricular patch at the appropriate level, establishing the plane of the annulus

• A separate atrial patch (usually autologous pericardium) closes the primum ASD
• The AV valve tissue is attached to the inferior edge of the atrial patch
• Sutures at the posteroinferior angle of the primum ASD are placed wide of the AV node (towards the coronary sinus) to protect the conduction system
• The coronary sinus may be placed on either side of the patch (left or right) depending on surgeon preference and anatomy

• A single large patch covers both ASD and VSD
• The AV valve is suspended to the patch at mid-level
• Simpler but may sacrifice AV valve tissue, leading to poorer valve function

• Saline testing of left AV valve before closing right atrium (check for regurgitation and stenosis)
• Intraoperative TEE after coming off bypass: assess AV valve competence, check for residual VSD/ASD, assess biventricular function
• Acceptable: trivial-mild residual MR; any more requires return to bypass

Post-operative Issues & Outcomes

• Sabiston, p. 2567-2458

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SURGICAL STRATEGY SUMMARY TABLE

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KEY SURGICAL EXAM MNEMONICS

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What's New / Expanded in This Version

• Full operative steps: right atriotomy vs. ventriculotomy vs. pulmonary arteriotomy by defect type
• Conduction anatomy with exact suture placement rules (anterosuperior safe, posteroinferior must go into RV muscle)
• Supracristal VSD: aortic cusp repair at same sitting
• Swiss-cheese VSD: PA banding, oversized patch, hybrid device closure
• Amplatzer device closure: indications and heart block risk

• Historical context: Blalock-Taussig 1944; classic vs. modified BT shunt with diagrams
• Full transatrial-transpulmonary repair steps
• Transannular patch decision criteria (Z-score <-2.5; PA/Ao ratio <0.5; RV/LV ratio >0.7)
• Anomalous LAD crossing RVOT: use RV-PA conduit (Hancock/homograft)
• TOF with pulmonary atresia + MAPCAs: unifocalisation surgery
• Late PVR: transcatheter Melody/Sapien valve criteria (RVEDVi >160 mL/m²)

• Full repair strategy by each VSD subtype
• Taussig-Bing without PS: ASO + VSD closure
• Taussig-Bing with PS: Rastelli, REV, or Yasui procedure
• Non-committed VSD: Rastelli-type tunnel + conduit; PA banding timing
• Conduit timing: delay until 2-3 years if extracardiac conduit needed (allows larger size)

• Full step-by-step ASO: great vessel transection → coronary transfer (trapdoor technique, Yacoub A-E configurations) → Lecompte manoeuvre → anastomoses → pericardial patch reconstruction
• DHCA in neonates
• LV retraining protocol (PA band + BT shunt)
• TGA-VSD with severe PS: Rastelli, REV, Nikaidoh procedures
• Mustard/Senning: full explanation of physiologic vs. anatomic correction and why they failed (systemic RV)

• Rastelli A/B/C classification with surgical implications
• Full two-patch technique step-by-step: AV valve division → cleft closure → VSD patch (with conduction system protection) → AV valve-to-patch suturing → ASD patch
• Diagram of AV node position at posteroinferior junction
• Pulmonary hypertensive crisis management post-op