MHD: Congenital Heart Disease

Question 1

What is meant by “the complex” in congenital heart diseases?

Answer 1

When a group of abnormalities tend to be associated and contribute together to altered economy of the heart

Question 2

What is a shunt?

Answer 2

A transfer of blood from one side of the circulation to the other through an abnormal pathway (Left to right, right to left)

Question 3

What is the major shunt associated with the atria?

Answer 3

Atrial septal defect (ASD)

Question 4

What is the major shunt associated with the ventricles?

Answer 4

Ventricular septal defect (VSD)

Question 5

What is the major shunt associated with the ducts?

Answer 5

Patent ductus arteriosus (PDA)

Question 6

What are the types of atrial septal defect?

Answer 6

Fossa ovalis (Secundum type)
Ostium primum type
Sinus venosus (proximal type)
Coronary sinus type

Question 7

Describe the blood flow through an atrial septal defect

Answer 7

Left to right shunt forms because the pressure in the left atrium is slightly higher than the right atrium and the right ventricle has a much larger compliance.
Result: volume hypertrophy of RA and RV, increased pulmonary flow

Question 8

Do ASDs typically cause cyanosis and hypoxemia?

Answer 8

No. L to R shunt moves some oxygenated blood back to pulmonary, but does not typically reverse.

Question 9

What is the most common type of VSD?

Answer 9

Subaortic: defect located just beneath the aortic valve through the membranous septum

Question 10

Describe the blood flow through a ventricular septal defect

Answer 10

Left to right shunt leads to volume hypertrophy of the left atrium, left ventricle, right ventricle and enlargement of the pulmonic orifice

Question 11

What is the natural history of VSDs?

Answer 11

Small defects can be asymptomatic, resolve in first few years of life.
VSDs increase risk for infective endocarditis

Question 12

What is Eisenmenger syndrome?

Answer 12

Reversal of shunt direction due to changes in vascular resistance
Ex: as defect progresses, pulmonary pressure can raise above the left sided pressure, leading to R to L shunting

Question 13

Describe the blood flow through a patent ductus arteriosus

Answer 13

Left to right shunt through the ductus arteriosus leads to volume hypertrophy of the LA and LV

Question 14

Which congenital defects increase pulmonary flow?

Answer 14

L to R shunts

ASD, VSD, PDA

Question 15

What are the reasons for the development of pulmonary hypertension in congenital heart defects?

Answer 15

Flow beyond the distensibility of the lung vasculature
Vasoconstriction of pulmonary vascular bed
Secondary pathologic changes in lung

Question 16

Which shunts are most likely to involve pulmonary hypertension

Answer 16

VSD > PDA > ASD

Question 17

Congenital pulmonary stenosis results in hypertrophy of what chamber?

Answer 17

Right ventricle

Question 18

Congenital aortic stenosis results in hypertrophy of what chamber?

Answer 18

Left ventricle

Question 19

What are the two types of supravalvular aortic stenosis?

Answer 19

Subaortic stenosis: involves fibroelastic tissue

Muscular: hypertrophic cardiomyopathy

Question 20

What is coarctation of the aorta?

Answer 20

Narrowing of the transverse aortic arch

Question 21

What is tetralogy of fallot?

Answer 21

A developmental defect leading to 4 anomalies:

1) Infundibular pulmonary stenosis
2) Right ventricular hypertrophy
3) VSD
4) Overriding aorta (receives blood from RV and LV)

Question 22

What is the infundibulum?

Answer 22

The outflow tract of the right ventricle

Question 23

What is the characteristic shape of the VSD in tetralogy of fallot?

Answer 23

U shaped

Question 24

What are the two types of tetralogy of fallot?

Answer 24

Cyanotic (more common)

Acyanotic

Question 25

Describe the effects of cyanotic tetralogy of fallot

Answer 25

Pressure hypertrophy of RA and RV due to pulmonary obstruction. LA and LV are typically smaller than normal.
Prominent R to L shunt leads to cyanosis

Question 26

Describe the effects of acyanotic tetrology of fallot

Answer 26

L to R shunt at ventricles, so no cyanosis

Hypertrophy of RV, RA, LA and LV

Question 27

What happens in Transposition of the Great Arteries?

Answer 27

Aorta originating from RV, pulmonary artery from LV
2 separate circuits in parallel as opposed to the normal in-series arrangement, oxygenation of systemic blood does not occur

Question 28

Why doesn’t TGA cause death during fetal development or early after birth?

Answer 28

The physiologic shunts (foramen ovale and ductus arteriosus) allow mixing between the two circuits, so some oxygenated blood is able to reach system.

These must remain open for the defect to be compatible with life.