View source for Transposition of the great arteries

==Background==
[[File:D-tga-575px.jpg|thumb|Dextro-transposition of the great arteries.]]
[[File:D-TGA.jpg|thumb|]]
*Type of cyanotic [[congenital heart disease]]
*Aorta arises from the right ventricle and the pulmonary artery from the left ventricle
*Results in two parallel circulations
**The first sends deoxygenated systemic venous blood to the right atrium and back to the systemic circulation via the right ventricle and aorta
**The second sends oxygenated pulmonary venous blood to the left atrium and back to the lungs via the left ventricle and pulmonary artery
*Incompatible with life unless there is communication between the two parallel circuits
**Mixing occurs either intracardiac (patent foramen ovale, [[VSD]] or [[ASD]]) '''OR''' extracardiac connections ([[patent ductus arteriosus]] or bronchopulmonary collateral circulation)
*Often associated with other cardiac abnormalities
**[[Ventricular septal defect]]s (VSD)
**Left ventricular outflow tract obstruction (dynamic or anatomical)
**Mitral and tricuspid valve abnormalities
**[[coronary artery anomalies|Coronary artery variations]]
*Prevalence in the United States is estimated to be 4.7 per 10,000 live births<ref>Improved national prevalence estimates for 18 selected major birth defects--United States, 1999-2001. MMWR Morb Mortal Wkly Rep. 2006;54(51):1301-5.</ref>
*Accounts for 3% of  all [[congenital heart disease]] and almost 20% of all cyanotic CHD defects <ref>Reller MD. Prevalence of congenital heart defects in metropolitan Atlanta, 1998-2005. J Pediatr. 2008;153(6):807-13.</ref>

==Clinical Features==
*Cyanosis, determined by amount of intercirculatory mixing
*[[shortness of breath (peds)|Tachypnea]]
*[[Murmur]]s
**Pansystolic murmur at lower left sternal border if there is a VSD
**Systolic ejection murmur along the upper left sternal border in patients with left ventricular outflow obstruction
*Diminished pulses in patients who also have [[coarctation of the aorta]] or interruption of the aortic arch

==Differential Diagnosis==
{{Congenital heart disease DDX}}

==Evaluation==
[[File:Transposition-of-great-vessels.jpg|thumb|"Egg on side/string" sign]]
[[File:Transposition great arteries Orphanet 1750-1172-3-27-2.jpg|thumb|Subcostal echo view showing discordant ventriculoarterial connections together with the presence of parallel, rather than crossing, great arteries arising from the ventricles.]]
[[File:Transposition great arteries Orphanet 1750-1172-3-27-1.jpg|thumb|Echocardiogram in transposition of the great arteries. This subcostal view shows the left ventricle giving rise to a vessel that bifurcates, which is thus identified as the pulmonary artery.
Abbreviations: RA=right atrium, RV=right ventricle, LV=left ventricle, PT=pulmonary trunk, LPA and RPA=left and right pulmonary artery.]]
*[[Echocardiography]]
*[[ECG]]
**Initial ECG often normal
*[[CXR]] 
**Classically with “egg on a string” appearance, thought to be a result of the great arteries forming a narrowed vascular pedicle when transposed
*Cardiac catheterization
**Remains the gold standard, but seldom required to make the diagnosis

==Management==
*Stabilization of cardiac and pulmonary function and ensure adequate systemic oxygenation
*[[Prostaglandin E1]]
**Provide sufficient intercirculatory mixing between the two parallel circulations by maintaining patency of the ductus arteriosus
**Start infusion at 0.05 mcg/kg/min IV and titrate up to 0.1 mcg/kg/min, monitoring for hypotension (and apnea)
**Maintains the ductus (which completely seals by ~3 wks)
**Side Effects: Hypotension, Bradycardia, Seizures and Apnea
*Balloon atrial septostomy
**Performed to stabilize patients with severe hypoxemia due to inadequate mixing between the two parallel circuits
**Balloon is placed across the atrial septum into the left atrium, inflated and then pulled vigorously back across the septum to produce an [[ASD]]
*Surgery, Arterial switch operation
**In rare instances, atrial switch operation when coronary artery anatomy makes arterial switch infeasible
**Typically performed within the first two weeks of life
*Most will die within the first year of life without treatment

==Disposition==
*Admit

==Medication Dosing==
{{MedicationDose
| drug = Prostaglandin E1
| dose = 0.05-0.1mcg/kg/min IV
| route = IV
| context = Maintain PDA patency, duct-dependent lesion
| indication = Transposition of the great arteries
| population = Pediatric
}}

==See Also==
*[[Congenital heart disease]]

==External Links==


==References==
<references/>

[[Category:Cardiology]]
[[Category:Pediatrics]]