Infants may occasionally be born with a condition where the aorta and pulmonary
ID: 222773 • Letter: I
Question
Infants may occasionally be born with a condition where the aorta and pulmonary trunk are transposed-that is, they are switched with respect to which ventricle they "leave" (transposition of the great arteries). A.) Explain how this affects the newborn's circulation, including exactly why this is very bad B.) What surgical intervention is required? 2 fetal shunts allow mixing off the blood between the left and right sides of the heart in newborns. These shunts normally close soon after birth. C) Why would keeping these shunts open be helpful to a newborn with transposition of the great arteries?Explanation / Answer
A) Explain how this affects the newborn's circulation , including why this is very bad.
TGA is also known as " Blue Baby Syndrome" because of the low amount of oxygen provided to the body.
Newborns with TGA will have cyanosis - blueish skin colour from the first day of birthitself.
TGA babies will have two separate blood flow circuits .One that circulates oxygen -poor blue blood from the
infants body back to the body. The second circuit involves recirculation of oxygen rich red blood from the
infants lungs back to the lungs .TGA proves to be fatal as without an additional heart defect
that allows mixing of oxygen-poor blue and oxygen-rich red blood, such as an atrial or ventricular septal
defect or a patent ductus arteriosus, babies with TGA will only have oxygen-poor blood circulating
through their bodies.
B ) What surgical intervention is required?
Immediate medical management of a newborn with transposition of the great arteries - TGA
is followed in order to establish safe oxygen levels and stabilize the cardiac and pulmonary
function of the newborn's heart.Apart from continous infusion of prostaglandin and performing
a procedure called " Balloon Atrial septosomy" , which temporarily stabilizes babies ,
corrective surgery has to be performed in the first week of life.
An aterial switch surgery has to be performed . The procedure involves cutting off the aorta and
pulnnary arteries just above the point where they leave the heart. These arteries are then reconnected
to the proper ventricle.In some cases if ventricular septal defects and atrial septal defects are present
the closure of these two is also performed. Babies with complex cases of TGA , wherein there is narrowing
below the pulmonary valve, usually aterial switch is not recommended but complex decisions are taken , to
evaluate and execute the best surgical options and treatment plans , on a case-to case basis.
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2 fetal shunts allow mixing of the blood between the left and right sides of the heart in newborns.
These shunts normally close soon after birth.
C)Why would keeping these shunts open be helpful to a newborn with transposition of the great arteries.
In infants with TGA a situation where the systemic (to the body) and pulmonary (to the lungs) circulations are in parallel rather than in series.
This means the oxygen-poor blue coloured blood returning from the body and flowing through the right atrium and right ventricle is pumped out to the aorta and to the body,
while the oxygen-rich red coloured blood returning from the lungs and coursing through the left atrium and ventricle is sent back to the lungs via the pulmonary artery.
If there is no place in the circulation circuit ,where the oxygen-rich and oxygen-poor blood can mix, all of the organs of the body will be deprived of necessary oxygen.
Hence for the survival of the newborn prior to performing corrective surgery the blood must mix somewhere in the heart or the body.
hence keeping these shunts open be helpful to a newborn with transposition of the great arteries.
Sometimes if a a ventricular septal defect (VSD) is present , this will allow some mixing, but often this does not allow enough mixing.