Fung: Congenital Heart Disease

Question 1

General term used to describe abnormalities of the heart and great vessels that are present from birth

Answer 1

congenital heart disease

Question 2

During what weeks of embryogenesis are congenital heart defects likely to occur?

Answer 2

during weeks 3 through 8 of gestation

Question 3

(blank)% of births have a congential cardiovascular defect and are the most common form of cardiovascular disease among children

Answer 3

1

Question 4

Explain fetal blood circulation

Answer 4

O2 rich blood from the placenta –> umbilical vein –> ductus venosus (bypasses liver) –> IVC –> right atrium –> foramen ovale (bypass right ventricle) –> left atrium –> left ventricle –> aorta –> umbilical arteries –> placenta

**ductus arteriosus from pulmonary trunk to aorta, shunts blood that did enter the right ventricle and out the pulmonary trunk

Question 5

What are the two main causes of congenital heart disease?

Answer 5

sporadic genetic abnormalities - single gene mutations, small chromosome deletions, trisomies, monosomies

or

environmental factors - congenital rubella, gestational diabetes, teratogens

Question 6

abnormal communication between chambers or blood vessels

Answer 6

shunt

Question 7

a complete obstruction in blood flow

Answer 7

atresia

Question 8

3 primary categories of congenital heart defects

Answer 8

left to right shunt
right to left shunt
obstruction

Question 9

What happens to the blood flow in a right to left shunt?

Answer 9

poorly oxygenated blood returning from the veins mixes with systemic arterial blood; these patients will become hypoxic and cyanotic

Question 10

What are some clinical features of right to left shunts?

Answer 10

clubbing of fingers and toes

polycythemia (increased RBCs)

Question 11

What causes tetralogy of fallot? What are the four cardinal features of tetralogy of fallot?

Answer 11

tetralogy of fallot occurs when the infundibular septum is displaced anterosuperiorly

1) ventricular septal defect
2) overriding aorta (forms the superior border of the VSD and overrides the defect of both ventricles)
3) obstruction of right ventricular outflow tract (pulmonary stenosis)
4. right ventricular hypertrophy

Question 12

Do patients with tetralogy of Fallot survive? How do these patients present at birth?

Answer 12

yes, patients can survive into adulthood and can undergo complete surgical repair; most patients are cyanotic at birth

Question 13

What to the clinical consequences of tetralogy of Fallot depend upon?

Answer 13

the degree of the pulmonic stenosis

if mild: resembles an isolated ventricular septal defect and is more like an isolated left to right shunt without cyanosis

if severe: greater resistance RV outflow and a right to left shunt, pulmonary arteries become hypoplastic and aorta dilates

Question 14

What is transposition of the great vessels?

Answer 14

when the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle

**normally the aorta is posterior to the pulmonary artery, but it is reversed here

Question 15

How does transposition of the great vessels occur?

Answer 15

develops due to abnormal formation of the truncal and aortopulmonary septa

Question 16

The outcome of transposition of the great vessels is dependent on what three things?

Answer 16

1. degree of mixing of blood (if the patient has a ventricular septal defect, they can compensate…if they have an unstable shunt, like a patent foramen ovale, they need surgery)
2. magnitude of tissue hypoxia
3. ability of the right ventricle to supply to systemic circulation

Question 17

If a patient has transposition of the great vessels and has an unstable shunt, what must they undergo?

Answer 17

they must undergo balloon atrial septostomy to open up and allow for mixing of bloos

Question 18

Clinical features of transposition of the great vessels? Can these patients live to adulthood?

Answer 18

right ventricular hypertrophy; atrophy of left ventricle

**right ventricle must supply the systemic circulation

with surgery, can survive into adulthood; otherwise, die w/i first months of life

Question 19

What is persistent truncus arteriosus?

Answer 19

this arises due to the failure of separation of the embryological truncus arteriosus into the aorta and pulmonary artery; results in a single great vessel that receives blood from both ventricles and the coronary circulation

Question 20

Regarding persistent truncus arteriosus, There is an associated VSD that produces systemic cyanosis and increased pulmonary blood flow. Why is this a concern?

Answer 20

danger of irreversible pulmonary HTN

Question 21

What is tricuspid atresia?

Answer 21

complete obstruction of the tricuspid valve orifice

Question 22

How does tricuspid atresia occur?

Answer 22

when there is unequal division of the atrio-ventricular canal, you get a large mitral valve and an underdeveloped right ventricle

Question 23

How do patients with tricuspid atresia present at birth? Do they survive into adulthood?

Answer 23

cyanotic at birth; very high mortality rate

Question 24

What is total anomalous pulmonary venous circulation?

Answer 24

when the pulmonary veins (oxygenated blood) fail to develop into the common pulmonary vein and directly join to the left atrium

Question 25

What can correct a total anomalous pulmonary venous circulation?

Answer 25

so if you have a patent foramen ovale (b/w the atria) or an atrial septal defect, then pulmonary venous blood can enter the atrium

Question 26

What are the clinical features of total anomalous pulmonary venous circulation?

Answer 26

volume/pressure overload leads to hypertrophy and dilation of the right heart; dilation of the pulmonary trunk; hypoplastic left atrium; possible cyanosis due to right to left shunt of the ASD

Question 27

Describe the blood flow and complications in a left to right shunt

Answer 27

increased pulmonary blood flow and volume (pulmonary circuit is usually low flow, low resistance); initially, body responds to increased blood flow with medial hypertrophy and vasoconstriction to maintain distal pressures and prevent pulmonary edema; over time, the pulmonary vasoconstriction can lead to obstructive intimal lesions; eventually, the pulmonary vascular resistance will reach systemic levels and will change the shunt to a right to left shunt (late cyanotic congenital heart disease)

Question 28

So what is the first response to the increased blood flow to the pulmonary circulation in a left to right shunt?

Answer 28

vasoconstriction of pulmonary vasculature to maintain pressure and prevent edema in the lungs; also there will be medial hypertrophy to withstand the higher pressures

Question 29

What happens to a left to right shunt over time?

Answer 29

the increased pulmonary vasoconstriction will cause obstructive lesions of the intima of the vessels (hyaline and hyperplastic arteriolosclerosis); eventually the resistance of the pulmonary vessels will reach systemic levels and convert the shunt to a right to left shunt (late cyanotic congenital heart disease)

Question 30

In cases of left to right shunts, at what point are the structural defects of congenital heart disease irreparable?

Answer 30

Once irreversible pulmonary hypertension develops the structural defects of CHD are irreparable

Question 31

List 3 examples of left to right shunts

Answer 31

atrial septal defect ventricular septal defect patent ductus arteriosus

Question 32

What is an atrial septal defect?

Answer 32

an abnormal fixed opening in the atrial septum caused by incomplete tissue formation that allows for communication of blood b/w the left and right atria **not the same as a patent foramen ovale

Question 33

What is the most common type of atrial septal defect?

Answer 33

secundum **result from deficient or fenestrated oval fossa near the center of the atrial septum

Question 34

What are two other types of atrial septal defects?

Answer 34

``` Primum (5%): occur adjacent to the AV valves Sinus venosus (5%) occur near the entrance of the SVC and may be associated with anomalous pulmonary venous return to the RA ```

Question 35

What are some clinical features of an atrial septal defect?

Answer 35

left to right shunt b/c lower pulmonary vascular resistance and greater distensibility of RV increased pulmonary blood flow --> murmur asymptomatic before age 30 and irreversible pulmonary HTN is abnormal

Question 36

What can you do to prevent complications of an atrial septal defect, like heart failure, paradoxical embolization, or pulmonary vascular disease?

Answer 36

surgical or catheter based repair!

Question 37

What is the formamen ovale used for in the fetus? What happens to this hole after birth?

Answer 37

the foramen ovale is a small hole in the atrial septum at the oval fossa - it allows oxygen rich blood from the placenta to bypass the lungs; after birth it is forced shut due to increased systemic pressure in 80% of people

Question 38

What is a patent foramen ovale?

Answer 38

Occurs in 20% of people; during times of increased pressure on the right side (bowel movement, coughing, sneezing), the flap can open and can create a right to left shunt

Question 39

This is the most common congenital cardiac defect

Answer 39

ventricular septal defect (VSD)

Question 40

T/F: Most VSDs occur in isolation

Answer 40

False; only 20-30% occur in isolation, while most VSDs are associated with another congenital anomaly

Question 41

3 types of VSDs

Answer 41

with the membranous interventricular septum below the pulmonary valve (infundibular) within the muscular septum (may be multiple - swiss cheese septum)

Question 42

What are the clinical features of a large VSD? Can these patients survive?

Answer 42

difficulties from birth usually membranous or infundibular significant left to right shunting **must be corrected

Question 43

Can patients with a small VSD survive?

Answer 43

yes, small VSDs are well tolerated and may close spontaneously

Question 44

What is the ductus arteriosus used for in the fetus?

Answer 44

shunts blood from the pulmonary artery to the aorta **close should happen shortly after birth

Question 45

What is a patent ductus arteriosus? Does it usu occur isolated or associated with another anomaly (VSD, coarctation of the aorta or pulmonic or aortic valve stenosis)?

Answer 45

when the PDA does not spontaneously close after birth; 90% occur as an isolated anomaly

Question 46

what are the clinical features of a patent ductus arteriosus?

Answer 46

usu asymptomatic at birth small PDAs no big deal larger PDAs start as a left to right shunt but can progress to Eisenmenger syndrome

Question 47

What can be used to keep a PDA open?

Answer 47

prostaglandin E

Question 48

Results from the embryologic failure of the superior and inferior endocardial cushions of the AV canal to fuse adequately Patients have incomplete closure of the AV septum and malformation of the tricuspid and mitral valves

Answer 48

atrioventricular septal defect

Question 49

Primum ASVD and cleft anterior mitral leaflet; mitral insufficiency

Answer 49

partial atrioventricular septal defect

Question 50

Large combined AV septal defect and a large common AV valve (hole in center of the heart) Communication of the four chambers --> volume hypertrophy; 1/3 of patients have Down syndrome

Answer 50

complete atrioventricular septal defect

Question 51

List three forms of obstructive congenital heart disease

Answer 51

1. coarctation of the aorta 2. aortic valvular stenosis 3. pulmonary valvular stenosis

Question 52

What is coarctation of the aorta? What genetic syndrome is it associated with?

Answer 52

common structural anomaly in which the aorta narrows in the area where the ductus arteriosus/ligamentum arteriosum enters; associated with Turner's syndrome

Question 53

Compare the infantile and adult forms of coarctation of the aorta. How are the symptoms different?

Answer 53

infantile: narrowing of the aortic arch proximal to the patent ductus arteriosus; symptomatic early on, high mortality rate if not surgically corrected; unsaturated blood through the PDA produces lower extremity cyanosis adult: discrete infolding of the aorta just opposite the ligamentum arterosum; distal to the arch vessels; symptoms include hypertension in upper extremities, weak pulses in lower extremities, claudication and coldness of lower extremities, development of collateral circulation in the are

Question 54

``` Common malformation May be isolated or be a part of a syndrome ( TOF, TGA) Resultant RVH Mild cases may be asymptomatic Severe cases require surgical repair ```

Answer 54

pulmonary stenosis

Question 55

No communication between the right ventricle and lungs Hypoplastic RV and ASD Blood reaches the lungs through a patent ductus arteriosus

Answer 55

pulmonary atresia

Question 56

Where is the aorta most likely to undergo stenosis?

Answer 56

1. valvular: cusps of aortic valve become hypoplastic, thickened or abnormal in number 2. subvalvular: thickened ring or collar of tissue below the valve, associated with a prominent systolic murmur, causes pressure hypertrophy of LV 3. supravalvular: thickening of ascending aorta causing luminal constriction

Question 57

What does severe aortic stenosis or atresia cause?

Answer 57

obstruction to LV outflow --> hypoplasia of the left ventricle and ascending aorta

Question 58

How do you correct severe aortic stenosis/atresia?

Answer 58

patent ductus arteriosus for life **nearly always fatal unless surgically repaired