Pathoma- Congenital heart defects Flashcards
At what stage of development do congenital defects usually arise?
Embryogenesis (between weeks 3-8)
How do defects with L→R shunts usually present at birth?
Asymptomatic at birth; however, Eisenmenger syndrome can occur and produce symptoms later on.
How do defects with R→L shunting present at birth?
Cyanosis due to mixture of deoxygenated blood with oxygenated blood that goes into systemic circulation.
Explain process of Eisenmenger syndrome
1) Starts out as L→R shunt. Blood goes to R side because pulmoanry circulation is the lower pressure circuit.
2) Icnreased through pulmonary circulation results in hypertrophy of pulmonary vessels and pulmonary HTN.
3) Increased pulmonary resistance eventually leads to reversal of shunt → late cyanosis with RVH, polycythemia, and clubbbing.
What are the 3 signs of Eisenmenger syndrome and why do they occur?
1) RVH: RV pumps against higher pressure due to pulmonary HTN
2) Polycythemia: deoxygenated blood goes into systemic circuit via R to L shunt → hypoxemia → release of erythropoietin → increased RBC.
3) Clubbing: change in finger nails secondary to cyanosis.
What type of congenital defect is the most common congenital herat defect?
VSD
What congenital defect is assocaited with fetal alcohol syndrome?
VSD
What type of shunt is VSD (L to R or R to L)? what determines the extent of this shunting/age of presentation of sx?
L to R shunt.
Size of defect determines extent of shunting and age at presentation.
What are the sx of VSD in small defects vs. large defects?
Small defects are asymptomatic. Large defects can lead to Eisenmenger syndrome.
Tx of VSD
Surgical closure; small defects may close spontaneously
What is the most common type of ASD?
Ostium secundum
What type of ASD is associated with Down syndrome?
Ostium primum
What shunt direction does ASD result in?
Left to right shunt
What type of heart sounds are associated with ASD and why?
Loud S1 with fixed split S2 (during inhalation + exhalation). This is because due to the left to right shunt, more blood enters the right side of the heart. As a result, there is delayed closure of the pulmonic valve both during inhalation and exhalation compared to aortic valve, resulting in a fixed, split S2.
What is paradoxical emobli? What is this a major complication of?
Emboli that results from the venous system. Usually, an embolus that breaks off from the venous system (e.g. DVT) enters the right side of the heart, goes to the pulmonary trunk, and can lodge in the lungs resulting in PE. However, in ASD, the embolus can enter the RA from the veins and cross over to the LA. Then it can enter the LV → aorta → lodge up in the brain, causing a stroke.
What congenital condition is associated with congential rubella?
PDA
What direction shunt is associated with PDA after birth?
Left to right shunt between aorta and pulmonary artery (blood goes from aorta to pulmonary artery)
What murmur is associated with PDA
Continuous machine-like murmur
How do kids with PDA present?
They are asymptomatic at birth; however, it can progress into Eisenmenger syndrome, resulting in lower extremity cyanosis. This is because the ductus arteriosus connects to the aorta from pulmonary trunk AFTER vessels leading to the head and neck. Thus, when pulmonary HTN occurs, the blood will shunt from R → L (pulmonary trunk to aorta), bypassing the first vessels that come off the aorta that reaches head and neck. As a result, deoxygenated blood will mix with oxygenated blood and supply the lower extremities, resulting in lower extremity cyanosis.
What is the tx of PDA?
Indomethacin, which decraeses PGE, resulting in PDA closure.
What maintains opening of the ductus arteriosus?
PGE
What characterizes Tetrology of Fallot?
1) VSD
2) Overriding aorta over VSD
3) Pulmonic stenosis (stenosis of RV outflow tract)
4) RVH
What type of shunt is associated with tetrology of fallot and wh?
R→L shunt; this is because the pulmonic stenosis “blocks” the pulmonary trunk. As a result, the blood goes into the aorta (overriding aorta from VSD), and deoxygenated blood goes into systemic circulation, which is a R→L shunt.
How does Tetralogy of Fallot present and why?
Early cyanosis. This is because the pulmonic stenosis “blocks” the pulmonary trunk. As a result, the blood goes into the aorta (overriding aorta from VSD), and deoxygenated blood goes into systemic circulation, which is a R→L shunt.
What determines the degree of stenosis in teralogy of fallot and why?
Pulmonic stenosis. If pulmonic stenosis is tight, there will be more R→L shunting and more blood will go into the overriding aorta. If it’s loose, some deoxygenated blood can still go into the pulmonary trunk and less will go into aorta.
Why do patietns squat in Tetralogy of Fallot?
Squatting increases the systemic vascular resistance. As a result, blood will go into pulmonary trunk instead of overriding aorta, allowing more blood to reach the lungs.
What condition is associated with a boot-shaped herat on x-ray?
Tetralogy of Fallot
What condition is associated with maternal diabetes?
Transposition of great vessels
What does transposition of great vessles present with?
Early cyanosis; due to systemic and pulmonary circulation not mixing. This is incompatible with life.
How can transposition of great vessels be treated short term until definitive surgical repair?
A creation of shunt after birth; PGE is administered to maintain PDA.
What anatomical changes to the heart results from transposition of great vessels?
Hypertrophy of RV and atrophy of LV
How does truncus arteriosus present and why?
Early cyanosis; bc deoxdygnated blood from RV mixes with oxygenated blood from LV before pulmonary and aortic circulations separate.
What is the defect in truncus atresia??
Tricuspid valve orifice fails to develop, resulting in hypoplasia (incomplete development) of RV
How does tricuspid atresia present and why?
Early cyanosis. This is bc tricuspid atresia is associated with ASD, resulting in R→L shunt. Blood from RA goes into LA instead of LV because of atresia and therefore deoxygenated blood enteres the left side of heart (systemic circulation).
Two forms of coarctation of aorta
Infantile vs. adult forms
What congenital heart defect is infantile coarctation associated with?
PDA; coarctation lies distal to aortic arch but before the PDA.
How do infants with coarctation present and why?
Presents with lower extremity cyanosis in infants often at birth. This is because the aortic coarcation lies proximal to the PDA. As a result, some deoxdygenated blood from pulmonary trunk will cross over to the aorta and supply lower extremities with mix of deoxygenated/oxygenated blood. The branches off of the aorta that supplies the head and upper extremities come off before the coarctation and therefore there is no cyanosis of upper body.
What condition is associated with infantile coarctation?
Turner syndrome
Is adult form of coarctation associated with PDA?
No
How does adult form of coarctation present and why?
HTN in upper extremities and hypotension with weak pulses in lower extremities. This is because the coarctation lies distal to the arch. Therefore, the branches off aorta come off before the coarctation and get lost of blood → HTN. However, due to the coarcation, less blood is able to go to the branches coming off aorta that supply the lower extremities → weak pulses and hypotension.
What defect is associated with adult coaractation?
Bicuspid aortic valve
What is associated with notching of the ribs on x-ray and why?
Adult form of coarctation. This is because not much of the blood can get to the descending aorta due to the coarctation. As a result, a collateral blood supply to the intercostal arteries forms, connecting asending and descending aorta. This resuls in engorgement of these intercostal vessels, leading to “notching of the ribs” on x-ray.
