Congenital Defects Flashcards
When do most congenital defects arise?
During embryogenesis (usually weeks 3-8)
What is the incidence and cause of congenital heart defects?
- Seen in 1% of live births
- Most defects are sporadic
What are the two different types of shunts that occur in congenital defects?
- Left to right - relatively asymptomatic at birth - but shunt can eventually reverse
- Right to left - presents as cyanosis shortly after birth
What is VSD (ventricular septal defect) associated with? What is it?
- Fetal alcohol syndrome
- Defect in the septum that divides the right and left ventricles
What is the most common heart defect?
Ventricular septal defect
What does VSD result in?
- Left-to-right shunt
- Size of defect determines extent of shunting and age at presentation
- Small defects are often asymptomatic
- Large defects can lead to eisenmenger syndrome
How does the VSD eventually cause cyanosis?
Inc. Pulmonary HTN –> reversal of shunt –> blue blood –> cyanosis
What is Eisenmenger syndrome?
RVH, polycythemia, clubbing (due to cyanosis)
What is an atrial septal defect (ASD)?
Defect in septum dividing right and left atria
-Results in Left to right shunt and split S2 on auscultation (increased blood in right heart delays closure of pulmonary valve)
What is the most common type of ASD?
Ostium secundum (90% of cases)
What is ostium premium type associated with?
Down Syndrome
What is an important complication of ASD?
Paradoxical emboli
-Can go through the shunt & you get emboli stroke rather than PE
What is a Patent Ductus Arteriosus (PDA)?
- Failure of ductus arteriosus to close
- Results in left-to-right shunt between aorta and the pulmonary artery
- -During development, the ductus arteriosus normally shunts blood from the pulmonary artery to the aorta, bypassing the lungs.
What maternal condition is PDA associated with?
Congenital Rubella
What symptoms are associated with PDA?
- Asymptomatic at birth with continuous “machine-like” murmur
- May lead to Eisenmenger syndrome, resulting in lower extremity cyanosis
What might you see on the lower extremities of PDA?
Lower extremity cyanosis
What do you use to treat PDA?
Indomethacin, which decreases PGE, resulting in PDA closure (PGE maintains patency of the ductus arteriosus)
What is Tetralogy of Fallot?
Characterized by (1) Stenosis of right ventricular outflow tract (2) Right ventricular hypertrophy (3) VSD (4) an aorta that overrides the VSD
What causes cyanosis in Tetralogy of Fallot?
Right to left shunt
-Degree of stenosis determines extent of shunting and cyanosis
What do you see on X-ray with Tetralogy of Fallot?
Boot-shaped heart
What do patients with Tetralogy of Fallot learn to do?
Squat in response to a cyanotic spell
-Increased arterial resistance decreases shunting and allows more blood to reach the lungs
What is transposition of the great vessels?
Characterized by pulmonary artery arising from the left ventricle and aorta arising from the right ventricle. (creates two continuous loops)
What does PGE do?
Keeps things open! Like PDAs
What maternal condition is Transposition of the great vessels associated with?
Maternal diabetes
What does Transposition of the great vessels present with?
- Early cyanosis
- Pulmonary and systemic circuits do not mix
What is required for survival with transposition of the great arteries?
-Creation of a shunt (allowing blood to mix) after birth
What is given to maintain PDA until surgical repair of transposition of the great vessels is performed?
PGE
What does Transposition of the great vessels do to the heart structure?
- Hypertrophy of the right ventricle
- Atrophy of the left ventricle
What is the Truncus Arteriosus?
Characterized by a single large vessel arising from both ventricles
-Truncus fails to divide
What does Truncus arteriosus present with?
Early Cyanosis
-Deoxygenated blood from right ventricle mixes with oxygenated blood from left ventricle before pulmonary and aortic circulations separate.
What is tricuspid atresia?
- Failure to form the tube lumen
- Tricuspid valve orifice fails to develop
- Right ventricle is hypoplastic
What is tricuspid atresia often associated with?
ASD
What type of shunting and cyanosis does tricuspid atresia cause?
- Right-to-left shunt
- Presents with early cyanosis
What is Coarctation of the Aorta?
- Narrowing of the aorta
- Classically divided into infantile and adult forms
What is the infantile form of Coarctation of the Aorta associated with?
PDA
-Coarctation lies after (distal to) the aortic arch but before (proximal to) the PDA
What does infantile Coarctation present with?
Lower extremity cyanosis in infants, often at birth
What is infantile Coarctation associated with?
Turner syndrome
What anatomy is associated with the adult form of coarctation of the aorta?
- Not associated with PDA
- Coarctation lies after (distal to) the aortic arch
What symptoms does adult Coarctation of the Aorta present with?
- HTN in upper extremities & hypotension with weak pulses in lower extremities.
- Classically discovered in adulthood
What extra circulation develops with Coarctation of the Aorta?
- Collateral circulation develops across the intercostal arteries
- Engorged arteries cause ‘notching’ of ribs on x-ray
What other anomaly is Coarctation of the Aorta associated with?
Bicuspid Aortic Valve
