Congenital Cardiac Anomalies Part 1
Part 1 of my review of congenital cardiac malformations for radiology board exams. After all parts have been released, download a free study guide here.
Study Guide/Show Notes:
What are key imaging features to identify the right atrium in a congenital cardiac malformation?
Potentially the best imaging feature to identify the right atrium is identification of the atrium into which the coronary sinus drains. Additional features are identification of the atrium from which the suprahepatic inferior vena cava drains. The superior vena cava insertion is more variable and less reliable to identify the true right atrium.
What are key imaging features to identify the left atrium in a congenital cardiac malformation?
The left atrium is best identified by searching for the atrium which has the finger-like atrial appendage. Pulmonary vein insertion is less reliable to identify the true left atrium.
What are key imaging features to identify the right ventricle in a congenital cardiac malformation?
Key features that can help identify the right ventricle include presence of the moderator band, identification of a more apical attachment of the atrioventricular valve (insertion of the AV valve is typically more apical in the right ventricle compared to the left ventricle), presence of the infundibulum, and a trabeculated appearance of the septum compared to a smoother septum on the left ventricular side.
What are key imaging features of Tetralogy of Fallot?
Tetralogy of Fallot is the result of failure of the right ventricular outflow track to fuse with the interventricular septum. On radiography look for decreased pulmonary blood flow and a boot-shaped heart with an upturned cardiac apex and possible right aortic arch. The four classic features of Tetralogy of Fallot are:
1. Right ventricular hypertrophy
2. Ventricular septal defect
3. Pulmonary stenosis
4. Overriding aorta
What is the prognosis in terms of survival of individuals with Tetralogy of Fallot following appropriate surgical repair?
Prognosis is excellent. Following surgical repair, there is at least 90% survival at 35 years following surgery. Note that degree of right ventricular outflow tract stenosis guides timing of repair and degree of clinical symptoms and symptom onset. Severe stenosis requires earlier surgical repair.
What is the most common type of atrial septal defect: ostium primum or ostium secundum?
Ostium secundum accounts for around 60% of atrial septal defects compared to 35% for ostium primum. Note that the final 5% is from sinus venosus atrial septal defects.
Classic associations to remember for board exams:
Ostium primum: associated with endocardial cushion defects, common in Trisomy 21 (Downs)
Ostium secundum: Holt-Oram syndrome which is autosomal dominant with congenital heart defects like ASD and VSD and coarctation of the aorta along with upper limb anomalies like radial and thumb aplasia and hypoplasia of the clavicle.
Sinus venosus ASD: partially anomalous pulmonary venous return
What are the components of the endocardial cushion?
The endocardial cushion results from formation of the lower atrial septum, ventricular septum, and the septal leaflets of the tricuspid and mitral valves.
What is the difference between a partial, transitional, and complete endocardial cushion defect?
A partial endocardial cushion defect has a canal passing through either the mitral or tricuspid valves but not both and may be asymptomatic. A transitional endocardial cushion defect has a canal through both the mitral and tricuspid valves and the atrial and/or ventricular septum. A complete endocardial cushion defect has a large septal defect and may have either a common or separate mitral valve and tricuspid valve. A complete endocardial cushion defect will have symptoms of congestive heart failure and a large left to right shunt and mitral regurgitation. Note that all of these will have an ostium primum atrial septal defect.
Nearly half of all individuals with an endocardial cushion defect will have Down’s syndrome. On imaging expect diffuse cardiac enlargement, a gooseneck deformity of the left ventricular outflow tract on angiography, and right greater than left increased pulmonary vascularity. A hypersegmented sternum and 11 ribs would be a manifestation of associated Trisomy 21.
What are common imaging findings suggestive of an atrial septal defect?
Atrial septal defects (without other associated cardiac anomalies) would manifest with enlargement of the right atrium and right ventricle with normal appearing left atrium and left ventricle. Associated asymmetric right pulmonary artery enlargement may be seen.
What is cor triatriatum?
As the name suggests—triatriatum—this is an entity in which there are essentially 3 atria due to to a congenital anomaly in which a membrane divides the left atrium into two with anterior and posterior chambers. Clinical symptoms are often pulmonary hypertension in children and this can be fatal. This appears similar to mitral stenosis on a chest radiograph with a normal-sized heart and pulmonary edema. There may be an associated atrial septal defect and anomalous pulmonary venous drainage. Early surgical intervention often leads to best outcomes.
What is the most common cyanotic congenital heart disease?
Tetralogy of Fallot
What is the so called pentalogy of Fallot?
The 4 findings characteristic of tetralogy of Fallot (ventricular septal defect, right ventricular outflow tract obstruction, overriding aorta and right ventricular hypertrophy) with additional finding of atrial septal defect or patent ductus arteriosus.
True or false? Tetralogy of Fallot is associated with a right-sided aortic arch in greater than 50% of cases.
False. A right-sided aortic arch is seen in approximately 25% of cases of Tetralogy of Fallot.
What are some of the most common causes of right ventricular outflow tract obstruction in cases of tetralogy of Fallot?
With tetralogy of Fallot, right ventricular outflow tract obstruction can result from valvular anomalies such as a hypoplastic pulmonary valve annulus or bicuspid pulmonary valve. Other contributors to right ventricular outflow tract obstruction can include infudibular stenosis and pulmonary artery hypoplasia.
Tetralogy of Fallot, along with many other congenital cardiac anomalies, have VACTERL associations. What are the principle components of VACTERL?
V: vertebral anomalies
A: anorectal anomalies such as anal atresia
C: cardiac anomalies and cleft lip
TE: tracheoesophageal atresia and/or esophageal atresia
R: renal anomalies and/or radial ray anomalies
L: limb anomalies such as polydactyly
What congenital cardiac anomalies are commonly associated with congenital rubella infection?
Congenital rubella infection is associated with both ventricular septal defects as well as tetralogy of Fallot. Additional features of congenital rubella infection can include deafness, intrauterine growth restriction, mental impairment and microcephaly. Note that rubella is one of the TORCH infections (Toxoplasomsosis, Other (syphilis, varicella zoster, parvovirus B19), Rubella, Cytomegalovirus, Herpes simplex virus) and primary infection by the mother is much higher risk for the developing infant than viral reinfection or reactivation.
Which trisomies are classically associated with congenital cardiac anomalies?
Notable trisomies associated with congenital cardiac anomalies include trisomy 13, trisomy 18, and trisomy 21. Note that nearly all cases of trisomy 13 and 18 will have a congenital cardiac anomaly and roughly half of trisomy 21 will have an associated congenital cardiac anomaly.
Name some cardiovascular anomalies associated with Turner syndrome.
Turner syndrome is notably associated with a bicuspid aortic valve and aortic coarctation with a notable risk of aortic dissection.
