Normal position of great arteries

• Aorta is posterior and right of pulmonary artery

Types of Transposition / malposition

• dTGA with intact ventricular septum
• lTGA
• dTGA with VSD
• Double outlet right ventricle with pulmonary stenosis
• Double outlet right ventricle without pulmonary stenosis
• Double outlet right ventricle with malposition of great arteries (Taussig Bing anomaly)

d-TGA with intact ventricular septum

• aorta is anterior and right of pulmonary artery

Clinical manifestations

• cyanosis and tachypnea within 1st hour of life
• hypoxia depends on the ducts and level of arterial shunting
• parasternal heave may be present
• soft systolic ejection murmur can be noted at the mid-left sternal border

Diagnosis

X-Ray

• Egg on string appearance
• normal to increased pulmonary flow (increases as PVR drops)

Saturation

• doesn't reach more than 90% even after patient breaths 100% oxygen (hypoxia test)

Echo

• confirms the translocation of arteries
• ducts and degree of mixing can also be accessed
• origin of coronary artery can also be accessed

Cardiac catheterization

• when non-invasive testing is inconclusive
• better tool for the location of coronary artery
• can also be used as a measure to create a temporary emergency balloon arterial septostomy (RASHKIND Procedure)
• systemic pressure = right atrial pressure

Treatment

Immediate

• Infusion of prostaglandin E1 (0.01-0.20 mcg/kg/min) - watch for risk of apnea
• if PgE1 fails - RASHKIND procedure

Treatment of choice

• Jantane procedure - within 2 weeks of birth
  • coronary arteries is reimplanted in neoaorta
  • avoid suture to the coronary artery
• 2 stages arterial switch procedure - if presented late
  • 1st stage - pulmonary banding
  • 2nd stage - arterial switch

Older procedures / Arterial switch operations

• Mustard or senning operation
  • blood from right atrium is diverted towards left atrium by means of a intraatrial baffle
• complications
  • atrial conduction disturbances
  • sick sinus syndrome
  • atrial flutter
  • sudden death
  • superior and inferior vena cava syndromes
  • edema
  • ascites
  • protein losing enteropathy
• right atrium remains as a pumping chamber - can lead to failure in teenage

d-TGA with VSD

d-TGA with small VSD

behaves similar to d-TGA with intact ventricular wall

d-TGA with large VSD

Clinical features

• subtle cyanosis
• cardiac failure
• large heart

X-ray

• narrow mediastinal width
• increased pulmonary vascularity

ECG

• prominent p wave
• right ventricular hypertrophy / biventricular hypertrophy
• right axis deviation

Echocardiography

• reveals TGA
• degree of mixing can also be identified

Cardiac catheterization

• equal pressures in both ventricles, aorta and pulmonary artery

Management

• surgery soon after diagnosis
• Heart failure, if develops is difficult to manage.
• Pre-operative management with diuretics can lessen sympoms of heart failure and stablize the patient

Surgery

• If no pulmonary stenosis - arterial switch with VSD Closure
• VSD maintains equal pressure in both ventricles and prevent LV mass regression, so results are equally good even if surgery is done in later periods

l-TGA / Ventricular inversion

• right atrium is connected to right ventricle which has mitral valve and smooth vessel morphological features of left ventricle
• left atrium is connected to left ventricle which has tricuspid valve and trabeculated normal features of a right ventricle
• Thus the physiology of circulation is correct
• also aorta is to the anterior (or side by side) and left of pulmonary artery
  

Clinical features

• If pulmonary outflow is obstructed - similar to isolated VSD
• if pulmonary outflow is stenosed - similar to TOF

Diagnosis

Chest X-ray

• abnormal position of arteries
• ascending aorta occupies upper left border of ascending aorta

ECG

• abnormal p waves
• absent Q waves in v₆
• abnormal Q waves in III, aVR, aVF and V₁
• upright t waves across pericardium

Echo

• right ventricle (moderator band, coarse trabaculations, tricuspid valve) sits inferiorly compared to the mitral valve

Management

• surgical correction of VSD (can be complicated by the bundle of His)
• Simple surgical correction may leave the right ventricle as the systemic pumping chamber and can lead to failure
• so recently Double switch operations have be done where outflow from right atrium is diverted to structural right ventricle and left atrium to structural left ventricle and then performing a arterial switch procedure

Double outlet right ventricle

Without pulmonary stenosis

• both aorta and pulmonary artery arise from right ventricle
• only outlet from left ventricle is the VSD
• similar to large VSD with left to right shunt

Diagnosis

ECG

• biventricular hypertrophy

Echo

• right ventricular origin of both the great arteries
• also show the location of great arteries in relation to VSD

Management

• depends on the location of great arteries in relation to VSD
  • VSD is subaortic
    • intracardiac tunnel is created
  • VSD is subpulmonic
    • arterial switch needed to be performed in addition to the intracardica tunnel
• Pulmonary arterial banding may be needed in infancy to prevent heart failure and correction can be done in older years

With pulmonary stenosis

• similar to that of TOF
• cyanosis will be marked

Double outlet right ventricle with malposition of great arteries (Taussig Bing Anomaly)

Types

• VSD is usually subpulmonic and aorta away from left ventricle (most common)
• both arteries close to VSD - doubly comitted
• neither arteries close to VSD - doubly uncomitted

Associations

• aortic obstructive lesion are common
  • coarctation of aorta
  • valvular and subvalvular aortic stenosis
  • interruption of aortic arch

Clinical features

• pulmonary blood flow is unobstructed
  • can cause heart failure in infancy
• aortic obstruction
  • can cause poor systemic flow
• cardiomegaly
• parasternal systolic ejection murmur - sometimes preceded by ejection click and loud clousre of pulmonary valve

ECG

• right axis deviation

X-ray

• cardiomegaly
• pulmonary plethora

Management

• pulmonary banding at infancy and surgical correction at later stages accompanied by arterial switch procedure combained with intracardiac baffle (or some modification of rastelli procedure)