Congenital Heart Defects Flashcards
What is a congenital defect?
People born with abnormality
What is dextrocardia?
Rare condition where heart points to right side of chest instead of left
What could dextrocardia be a result of?
- Abnormal cardiac looping 2. Induced during gastrulation (week 3) when laterality (right and left side) is determined
What other structural defects could isolated dextrocardia be associated with?
Abnormal connections with veins and arteries or abnormal septation of the heart
In a foetus, what is purpose of ductus arteriosus?
Connection between aorta and pulmonary artery (2 vessels leaving heart), allowing blood to bypass lungs as baby receives O2 from mother’s circulation
What causes ductus arteriosus to close after birth? What is purpose of it closing?
Increasing O2 tension and decrease in circulating prostaglandins Blood can then bypass heart and go straight to lungs
What happens if ductus arteriosus fails to close?
Causes too much blood to circulate to baby’s lungs and heart. Oxygenated blood travels back to the lungs, then returns to the heart to be pumped out again. Increase workload of heart.

What can patent ductus arteriosus lead to?
- Pulmonary hypertension 2. Heart failure 3. Ventricular hypertrophy
How can patent ductus arteriosus lead to pulmonary hypertension?
Too much blood circulating through the heart’s main arteries through a patent ductus arteriosus can lead to pulmonary hypertension, which can cause permanent lung damage
How can patent ductus arteriosus lead to heart failure?
A patent ductus arteriosus can eventually cause the heart to enlarge and weaken
What is a patent ductus arteriosus treated with?
Prostaglandin inhibitors (e.g. ibuprofen)
What can atrial septal defects be caused by?
Failure of septum primum and secundum to fuse after birth
What can cause failure of septum primum and secundum to fuse?
Malformations in the septum primum or secundum (most common) such that they don’t overlap. Leaves gap so blood can flow between atria.
What is a patent foramen ovale?
Foramen ovale (small, flap-like opening present in wall between right and left atria) fails to close during infancy
How common is a patent foramen ovale?
1 in 4 people
Why is a patent foramen ovale usually asymptomatic?
Higher pressure in LA pushes septum primum against septum secundum and mechanically shuts valve
When can a patent foramen ovale cause problems?
If there is higher pressure in RA this can push the flimsy septum primum open and allow blood to shunt from right to left
What is the ostium/foramen secundum?
A foramen in the septum primum (not the same as the foramen ovale which is an opening in the septum secundum)
What is an ostium secundum defect? What is it caused by?
Caused by excessive apoptosis in septum primum causing abnormally large opening. Or by inadequate development of the septum secundum – such as when the foramen ovale and foramen secundum overlap.
What is result of ostium secundum defect?
Blood is shunted left to right - Can cause enlargement of right atrium and ventricle - Small defects are asymptomatic (<5mm)
What is a ‘common atrium’?
Complete absence of atrial septum
What is ‘common atrium’ caused by?
Failure of development of septum primum and secundum
What is result of premature closing of foramen ovale?
Results in hypertrophy of the right side of the heart and underdevelopment of the left side - No blood passing into left side so it doesn’t develop - Death usually occurs shortly after birth
When does premature closing of foramen ovale occur?
During prenatal life


