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Detailed information of TRANSPOSITION OF THE GREAT ARTERIES
TRANSPOSITION OF THE GREAT ARTERIES
DEFINITION:
A cyanotic congenital heart disease characterized by parallel
systemic and pulmonary circulations.
EPIDEMIOLOGY:
- incidence: 2/10,000 live births
- accounts for 5-10% of all congenital cardiac lesions
- risk factors:
- associated anomalies (complex transposition):
- with VSD
- with PS
- with VSD + PS
- with PDA
PATHOPHYSIOLOGY:
- systemic (unoxygenated) blood is recirculated through the
body and the pulmonary (oxygenated) blood is recirculated
throught the lungs and so a communicating lesion (ASD, VSD, PDA)
is necessary for survival
2. Historical Perspectives
1950 - Blalock & Honton
- first to treat TGA by creating an ASD
1959 - Senning
- first to surgically correct a TGA by plastic revision of
the atria to reverse the venous outflow
CLINICAL FEATURES:
- from birth and intense if no associated anomalies
- increases with crying
- usually blue baby boy with no history of fetal or maternal
distress
2. Congestive Heart Failure
- in older infants with complex transposition
- dyspnea, irritability, feeding difficulties, etc
2. Signs
- newborn - cyanosis
- infants - clubbing
2. Palpation
- parasternal lift (RVH)
- @ LLSB with medial migration of apex
3. Auscultation
- S1 - normal
- S2 - single & loud
2. Murmers
- uncommon with intact septum
- soft pulmonary ejection murmer
- soft PDA murmer
INVESTIGATIONS:
- newborn - cardiac enlargement with increased pulmonary
vascular markings
- infant - cardiac enlargment with an "egg-shaped" heart
2. ECG
- newborn - normal
- infants - RAD, RVH
3. Hyperoxic Test
- cyanosis poorly responsive to an increase in FiO2
- if FiO2 100% then:
- PaO2 >150 mmHg - shunt at lungs
- PaO2 < 35 mmHg - shunt at heart & duct dependent
- PaO2 between 35-150mmHg - mixed lesion
MANAGEMENT:
- correct acidosis, low blood sugar, hypocalcemia
2. PGE1
- principle - create a shunt at the ductal level
- improves PaO2 within 10-20 minutes
- SE: jitteriness, seizures, apneas, vasodilatation with
hypotension, fever, peripheral edema, diarrhea
2. Surgical
- to produce a temporary shunt at the level of the atria
2. Types
- Balloon Atrial Septostomy (Rashkind procedure)
- Blalock-Hanlon repair
2. Atrial Switch Procedure
- switch at the atrial level so the systemic venous return
passes into the left atrium, left ventricle, and into the
pulmonary artery
- the right ventricle assumes the role of the systemic
ventricle
2. Types
- a pantaloon-shaped baffle is inserted to direct the
pulmonary venous return into the right atrium, right
ventricle, and aorta
2. Senning Procedure
- same as the Mustard but uses less foreign material and
more autologous tissue
3. Complications
- low mortality but high long-term morbidity from baffle
obstruction (kinking, thrombosis) and conduction
disturbances (sick sinus syndrome, atrial conduction
disturbances, etc.)
3. Arterial Switch Procedure
- switch at the arterial level
- must be performed within the first four weeks of life
before the left ventricle regression following the normal
postnatal reduction of the pulmonary vascular resistance
2. Types
- the pulmonary artery is sutured onto the RV out-flow
tract and the aorta and coronary arteries are sutured onto
the LV outflow tract
3. Complications
- survival rate of 80-90%
- coronary artery damage
4. Rastelli Procedure
- used if transposition is associated with pulmonary
stenosis (switch procedure would result in the
transformation of the PS into an Aortic Stenosis
- any VSD is closed and a baffle connects the right
ventricle to the pulmonary artery
2. Complications
- baffle obstruction (kinking and thromboses)
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