SLIDE 1: Transposition of Great Vessels (TGA) - Overview

• In TGA, the aorta arises from the right ventricle and the pulmonary artery from the left ventricle
• Aorta lies anterior and to the right of the pulmonary artery - also called D-TGA
• Systemic and pulmonary circulations are parallel (not in series) - survival depends on mixing
• Classified into: (a) TGA with intact ventricular septum and (b) TGA with VSD
• TGA + VSD is further subdivided into cases with and without pulmonic stenosis

SLIDE 2: TGA - Pathophysiology

• Oxygenated pulmonary venous blood recirculates in lungs; systemic venous blood recirculates systemically
• Pulmonary artery saturation is always higher than aortic saturation
• Survival depends on mixing between the two circulations
• Best mixing site (with intact septum): patent foramen ovale / atrial communication
• Small atrial communication = very poor mixing → severe hypoxemia soon after birth
• VSD of adequate size improves mixing
• As fetal pulmonary vasculature regresses → congestive failure around 4-10 weeks

SLIDE 3: TGA - Clinical Features (Intact Septum)

• Neonates are cyanotic at birth
• Rapid breathing and congestive failure within the first few days of life
• Severe cyanosis, congestive failure, normal first sound, single second sound
• Insignificant grade 1-2 ejection systolic murmur
• ECG: right axis deviation and right ventricular hypertrophy
• CXR: Cardiomegaly with narrow base and plethoric lung fields - classic "egg on side" appearance
• Thymic shadow often absent

SLIDE 4: TGA with VSD - Clinical Features

• Increased pulmonary blood flow; mixing at ventricular level determines severity of cyanosis
• Congestive failure around 4-10 weeks of age
• Cyanosis, cardiomegaly, congestive failure
• Normal first sound, single or normally split second sound
• Grade II-IV ejection systolic murmur; apical third sound gallop
• Mid-diastolic rumble may be present
• ECG: right axis deviation with biventricular, right ventricular or left ventricular hypertrophy
• CXR: Cardiomegaly, plethoric lung fields, features of pulmonary venous hypertension

SLIDE 5: TGA - Treatment

• Prostaglandin E₁ - reduces cyanosis in selected cases by keeping the PDA open
• Balloon Atrial Septostomy (BAS) - interim palliation; can be done in cath lab or ICU under echo guidance; effective up to 6-12 weeks of age
• Arterial Switch Operation (ASO) - treatment of choice; pulmonary artery and aorta are transected and re-anastomosed; coronary arteries transferred to neo-aortic root
• Window for arterial switch: first 4 weeks (LV regresses rapidly after birth)
• Senning operation - alternative in infancy if LV has regressed; not ideal long-term (RV remains systemic ventricle)
• With sizable PDA or VSD: operate within 2-3 months
• Operative mortality: <3%; 20-year survival >90%

SLIDE 6: Corrected TGA (L-TGA)

• Right atrium connected to left ventricle; left atrium connected to right ventricle
• Left ventricle gives rise to pulmonary artery; right ventricle gives rise to aorta
• Aorta lies anterior and to the left of pulmonary artery (hence L-TGA)
• Blood flow route is functionally normal - it is the associated anomalies that determine clinical features
• Common associated anomalies:
  • VSD (with or without pulmonic stenosis)
  • Left-sided Ebstein anomaly of tricuspid valve
  • Complete atrioventricular (AV) conduction block (~65% of cases)
• ECG: Precordial leads V4R, V1, V2 may show a Q wave absent in left precordial leads
• CXR: Smooth left upper border from ascending aorta
• Management is complex due to need to retain morphologic left ventricle as the systemic ventricle

SLIDE 7: Total Anomalous Pulmonary Venous Connection (TAPVC) - Overview

• All pulmonary veins connect anomalously to the right atrium (not left atrium)
• Anatomical classification:
  • Supracardiac - veins join left innominate vein or right superior vena cava
  • Cardiac - veins join coronary sinus or enter right atrium directly
  • Infracardiac - common pulmonary vein drains into portal vein
  • Mixed variety
• Survival depends on right-to-left shunt through patent foramen ovale or ASD
• Classified into: (a) with pulmonary venous obstruction and (b) without obstruction

SLIDE 8: TAPVC - Hemodynamics

• Pulmonary venous blood reaches right atrium along with systemic venous blood → complete mixing
• Oxygen saturation in pulmonary artery is often identical to that in the aorta
• Pulmonary venous obstruction → pulmonary arterial hypertension + restriction to pulmonary blood flow → presents early (first few weeks)
• Without obstruction → large pulmonary blood flow → cardiac failure between 4-10 weeks of age
• Infracardiac TAPVC is always obstructed

SLIDE 9: TAPVC - Clinical Features

• Cyanosis and congestive failure as fetal pulmonary vasculature regresses (~4-10 weeks)
• Accentuated first sound, widely split and fixed second sound
• Grade 2-4 pulmonary ejection systolic murmur + tricuspid flow murmur
• Continuous venous hum audible at upper left/right sternal border
• CXR: "Snowman" or "figure of 8" sign (supracardiac type, seen after age 2 years)

• Marked cyanosis and congestive failure within first 1-2 weeks of life
• Often fatal without specific treatment
• CXR: Cardiomegaly with plethoric lung fields (non-obstructive) OR "ground glass" appearance (obstructive infracardiac - resembles hyaline membrane disease)

SLIDE 10: TAPVC - Management

• Obstructed TAPVC = surgical emergency (short notice)
• Non-obstructed TAPVC = operate as early as possible; 80% of infants die within 3 months without surgery
• Surgery results are good in most modern centers
• Small proportion develop progressive pulmonary venous obstruction post-repair (difficult to correct)
• Echocardiography: confirms diagnosis, identifies individual pulmonary veins, assesses obstruction site, and quantifies PA pressure

SLIDE 11: Additional Cyanotic CHD with High Pulmonary Flow

• Single ventricle (no obstruction to pulmonary flow)
• Persistent truncus arteriosus
• Tricuspid atresia (without pulmonary obstruction)
• Double outlet right ventricle (without pulmonic stenosis)

• Congestive failure in neonatal period
• Cyanosis, cardiomegaly, failure to thrive
• ~80% die within 3 months without treatment
• Survivors develop pulmonary arterial hypertension (PVOD)
• Echocardiography needed for specific diagnosis
• Refer early to specialized centers; surgical treatment dictated by anatomy

SLIDE 12: Eisenmenger Syndrome - Overview

• Severe pulmonary arterial hypertension (PAH) resulting in right-to-left shunt
• Shunt may be at atrial, ventricular, or pulmonary arterial level
• Eisenmenger complex = PAH with VSD providing the right-to-left shunt
• PAH is due to pulmonary vascular obstructive disease
• Right ventricle has only concentric hypertrophy without significant increase in size

SLIDE 13: Eisenmenger Syndrome - Clinical Features

• History of cyanosis, fatigue, effort intolerance, dyspnea
• History of repeated chest infections in childhood
• Physical: cyanosis and clubbing
• Parasternal heave, palpable and loud second sound
• S2: Single (VSD), normally split (PDA), widely split and fixed (ASD)
• Pulmonary ejection click (with PDA) - heard in inspiration and expiration
• Harsh, high-pitched early diastolic pulmonary regurgitation murmur (Graham-Steell murmur)
• Differential cyanosis (lower limbs more cyanotic than upper limbs) with PDA directed to descending aorta

SLIDE 14: Eisenmenger Syndrome - Investigations & Treatment

• Prominence of pulmonary arterial segment
• Large right and left main pulmonary arteries
• Oligemic peripheral lung fields (pruning)
• Hilar area suggests pulmonary artery enlargement

• Prevention is ideal - early diagnosis and correction of all CHD with increased pulmonary blood flow
• Patients develop Eisenmenger physiology very early - must be operated by 2-3 months of age
• Medications available for PAH management (pulmonary hypertension drugs)
• May help reduce symptoms and improve survival

SLIDE 15: Aortic Stenosis - Overview

• Site of obstruction: at valve level (valvar), above the valve (supravalvar), or below the valve (subvalvar)
• Valvar AS: results from unicuspid or bicuspid aortic valve; aortic valve annulus may be small
• Supravalvar AS: obstruction in root of aorta, above aortic valve - as in Williams syndrome
• Subvalvar AS: may be discrete (membranous), fibromuscular, or muscular (hypertrophic obstructive cardiomyopathy)

• Obstruction overcome by raising LV systolic pressure → concentric hypertrophy of LV
• Powerful, muscular LV - emptying is complete but systole is prolonged → delayed A2
• Characteristic diamond-shaped (crescendo-decrescendo) systolic murmur
• Mid-systolic aortic component of second sound with mid-systolic thrill peak
• Prolonged ejection = peak slowly rises to sustained plateau then has slow-down slope
• Low amplitude, prolonged duration pulse