Pathoma- Congenital heart defects

Question 1

At what stage of development do congenital defects usually arise?

Answer 1

Embryogenesis (between weeks 3-8)

Question 2

How do defects with L→R shunts usually present at birth?

Answer 2

Asymptomatic at birth; however, Eisenmenger syndrome can occur and produce symptoms later on.

Question 3

How do defects with R→L shunting present at birth?

Answer 3

Cyanosis due to mixture of deoxygenated blood with oxygenated blood that goes into systemic circulation.

Question 4

Explain process of Eisenmenger syndrome

Answer 4

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.

Question 5

What are the 3 signs of Eisenmenger syndrome and why do they occur?

Answer 5

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.

Question 6

What type of congenital defect is the most common congenital herat defect?

Answer 6

VSD

Question 7

What congenital defect is assocaited with fetal alcohol syndrome?

Answer 7

VSD

Question 8

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?

Answer 8

L to R shunt.

Size of defect determines extent of shunting and age at presentation.

Question 9

What are the sx of VSD in small defects vs. large defects?

Answer 9

Small defects are asymptomatic. Large defects can lead to Eisenmenger syndrome.

Question 10

Tx of VSD

Answer 10

Surgical closure; small defects may close spontaneously

Question 11

What is the most common type of ASD?

Answer 11

Ostium secundum

Question 12

What type of ASD is associated with Down syndrome?

Answer 12

Ostium primum

Question 13

What shunt direction does ASD result in?

Answer 13

Left to right shunt

Question 14

What type of heart sounds are associated with ASD and why?

Answer 14

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.

Question 15

What is paradoxical emobli? What is this a major complication of?

Answer 15

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.

Question 16

What congenital condition is associated with congential rubella?

Answer 16

PDA

Question 17

What direction shunt is associated with PDA after birth?

Answer 17

Left to right shunt between aorta and pulmonary artery (blood goes from aorta to pulmonary artery)

Question 18

What murmur is associated with PDA

Answer 18

Continuous machine-like murmur

Question 19

How do kids with PDA present?

Answer 19

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.

Question 20

What is the tx of PDA?

Answer 20

Indomethacin, which decraeses PGE, resulting in PDA closure.

Question 21

What maintains opening of the ductus arteriosus?

Answer 21

PGE

Question 22

What characterizes Tetrology of Fallot?

Answer 22

1) VSD
2) Overriding aorta over VSD
3) Pulmonic stenosis (stenosis of RV outflow tract)
4) RVH

Question 23

What type of shunt is associated with tetrology of fallot and wh?

Answer 23

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.

Question 24

How does Tetralogy of Fallot present and why?

Answer 24

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.

Question 25

What determines the degree of stenosis in teralogy of fallot and why?

Answer 25

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.

Question 26

Why do patietns squat in Tetralogy of Fallot?

Answer 26

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.

Question 27

What condition is associated with a boot-shaped herat on x-ray?

Answer 27

Tetralogy of Fallot

Question 28

What condition is associated with maternal diabetes?

Answer 28

Transposition of great vessels

Question 29

What does transposition of great vessles present with?

Answer 29

Early cyanosis; due to systemic and pulmonary circulation not mixing. This is incompatible with life.

Question 30

How can transposition of great vessels be treated short term until definitive surgical repair?

Answer 30

A creation of shunt after birth; PGE is administered to maintain PDA.

Question 31

What anatomical changes to the heart results from transposition of great vessels?

Answer 31

Hypertrophy of RV and atrophy of LV

Question 32

How does truncus arteriosus present and why?

Answer 32

Early cyanosis; bc deoxdygnated blood from RV mixes with oxygenated blood from LV before pulmonary and aortic circulations separate.

Question 33

What is the defect in truncus atresia??

Answer 33

Tricuspid valve orifice fails to develop, resulting in hypoplasia (incomplete development) of RV

Question 34

How does tricuspid atresia present and why?

Answer 34

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).

Question 35

Two forms of coarctation of aorta

Answer 35

Infantile vs. adult forms

Question 36

What congenital heart defect is infantile coarctation associated with?

Answer 36

PDA; coarctation lies distal to aortic arch but before the PDA.

Question 37

How do infants with coarctation present and why?

Answer 37

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.

Question 38

What condition is associated with infantile coarctation?

Answer 38

Turner syndrome

Question 39

Is adult form of coarctation associated with PDA?

Answer 39

No

Question 40

How does adult form of coarctation present and why?

Answer 40

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.

Question 41

What defect is associated with adult coaractation?

Answer 41

Bicuspid aortic valve

Question 42

What is associated with notching of the ribs on x-ray and why?

Answer 42

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.