Congenital Cardiac Anomalies Part 3
Part 3 of my review of congenital cardiac anomalies for radiology board exam preparation. Access the free study guide on this topic by clicking here.
Study Guide/Show Notes:
Patent ductus arteriosus involves a patent connection between which structures?
Patent ductus arteriosus involves patency of the duct between the aorta and the pulmonary artery/pulmonary arterial system.
Within what time from does the ductus arteriosus normally close?
Approximately 24 to 48 hours after birth the ductus arteriosus will functionally close. Anatomic full closure can take about a month.
Why can a patent ductus arteriosus potentially be lifesaving with certain congenital cardiac anomalies?
In certain congenital cardiac anomalies, maintaining persistence of the ductus arteriosus can be key for survival or well-being of the infant as this allows blood to flow between the aorta and pulmonary arterial system. In cases of tetralogy of Fallot, pulmonary atresia, hypoplastic left heart, and Eisenmenger syndrome, this aberrant blood flow pathway through the patent ductus arteriosus can be beneficial.
What types of treatments can be considered to close a patent ductus arteriosus?
Treatments include endovascular coiling/closure, surgical clipping or ligation, or medical therapy.
What medical therapy exists to help keep the ductus arteriosus open and what medical therapy exists to help close the ductus arteriosus?
To help keep the ductus arteriosus open, prostaglandin E1 can be used.
To help close the ductus arteriosus, indomethacin can be used.
Note on board exams, associations to keep in mind with patent ductus arteriosus include prematurity, cyanotic heart disease, and maternal rubella.
With patent ductus arteriosus, imaging appearance can vary depending on the direction of blood flow through the ductus and the presence of co-existing cardiac abnormalities. However, in an uncomplicated case, imaging may show cardiomegaly with left heart enlargement, AP window obscuration, and pulmonary edema.
For atrial septal defect, is the ostium primum or secundum type most common?
Secundum atrial septal defects are most common. With atrial septal defects, secundum is #1, NOT #2 as the name could suggest.
True or false: Secundum atrial septal defects often do not close on their own.
False. Secundum atrial septal defects often do close on their own. Primum atrial septal defects are less likely to close on their own and can also be difficult to close with device closure as they are often close to atrioventricular valvular tissue.
Note some key associations with atrial septal defects include:
Ostium primum atrial septal defect: Down’s syndrome
Sinus venosus atrial septal defect: partial anomalous pulmonary venous return
The egg on a string appearance on a frontal chest radiograph is classic for which entity?
Transposition of the great arteries (classic for D-TGA). Top cause of cyanosis in early neonatal life, often related to closure of the patent ductus arteriosus and/or patent foramen ovale which close after birth and help provide blood flow between the pulmonary and aortic circulation. Risk factors include maternal diabetes. D-TGA requires surgery to correct. L-TGA often doesn’t require surgery but is “congenitally corrected”.
On board exams, if you are shown a frontal radiograph of an infant that has cyanosis and a right aortic arch, what are the top two congenital cardiac anomalies you should first consider?
Truncus arteriosus and tetralogy of Fallot. If there is increased pulmonary vascularity you would suspect truncus arteriosus. If decreased pulmonary vascularity you would expect tetralogy of Fallot.
We already covered the 5 T’s of cyanotic congenital heart disease on the prior episode. What are the most common differential considerations for non-cyanotic congenital heart disease?
Congenital heart disease without cyanosis should most commonly make you consider atrial and ventricular septal defects, patent ductus arteriosus, post-ductal aortic coarctation, and partial anomalous pulmonary venous return.
True or false: Adrenal insufficiency can cause small heart size?
True. Adrenal insufficiency (Addison’s) is a top differential consideration for a heart that is too small. Additional considerations can include malnourishment/cachexia of various causes and constrictive pericarditis.
Congestive heart failure in a newborn should make you think more about right-sided or left-sided cardiac obstruction?
Functional left heart cardiac obstruction is associated with newborn congestive heart failure. Think of entities like pre-ductal aortic coarctation, mitral stenosis, aortic stenosis, hypoplastic left heart, cor triatriatum, and infracardiac total anomalous pulmonary venous return. Note that with total anomalous pulmonary venous return, having a large patent foramen ovale or atrial septal defect aids in survival. Supracardiac total anomalous pulmonary venous return is most common and gives the classic snowman appearance on a frontal chest radiograph. Infracardiac pulmonary venous return is less common, but still shows up a lot on board exams and will show pulmonary edema in a new born.
True or false: Total anomalous pulmonary venous return is associated with asplenia?
True. In fact, nearly all cases of asplenia will have co-existing total anomalous pulmonary venous return. Note that asplenia is essentially bilateral right-sidedness. The majority of these individuals will also have an endocardial cushion defect. Also remember the association between Downs syndrome and endocardial cushion defects.
True or false: Truncus arteriosus essentially always has an associated ventricular septal defect.
True. Truncus arteriosus is a cyanotic congenital anomaly wherein a common trunk provides both the systemic and pulmonary circulation instead of a separate pulmonary artery and proximal thoracic aorta. Truncus arteriosus is classically taught to always have an associated ventricular septal defect. Other high-yield associations include DiGeorge (Catch 22) syndrome aka 22q11.2 deletion syndrome, CHARGE syndrome, and a right aortic arch.
CATCH 22
C=cardiac anomalies
A-abnormal facies
T=thymic aplasia
C=cleft palate
H=hypocalcemia/hypoparathyroidism.
22=22q11.2 deletion
CHARGE: From CHD7 mutation
C=coloboma (eye formation anomaly)
H=heart defects
A=atresia choanae
R=retarded growth and development
G=genital hypoplasia
E=ear anomalies with possible deafness
True or false: Turner syndrome is associated with post-ductal aortic coarctation.
False. Turner’s syndrome is associated with pre-ductal aka infantile aortic coarctation. Adult-type coarctation is post-ductal. In pre-ductal coarctation the patent ductus arteriosus become an important conduit for blood to flow from the pulmonary circulation into the more distal aorta.
Note that aortic coarctation in general is strongly associated with a bicuspid aortic valve and berry aneurysms among other anomalies. Look for rib notching of the 4th to 8th ribs, but not 1st and 2nd ribs as they have separate blood supply from the costocervical trunk as well as the “figure 3 sign” on a frontal chest radiograph from the aortic anomaly.
Note that Turner syndrome is also highly tested on board exams. Other Turner associations include horseshoe kidney, gonadal dysgenesis, hypothyroidism due to thyroid antibodies, antenatal cystic hygroma on ultrasound, etc.
Note:
Content I haven’t covered on these episodes includes surgical repair/correction for many of these congenital defects. Studying the surgical repair options is best with visual diagrams and you can find plenty of info on this in existing board prep books and online. You should be comfortable with the options and imaging appearances of surgical repair of transposition of the great arteries and tetralogy of Fallot, among other congenital cardiac anomalies.
