5. Congenital Heart Disease

Question 1

Congenital heart disease (CHD)

Answer 1

Cardiac or large vessel abnormalities present at birth

Most CHDs result from defective embryogenesis during gestational weeks 3-8

CHDs most common cardiac disease among children

Severe abnormalities - incompatible with intrauterine survival
Defects involving specific chambers or regions allow for live birth

Question 2

Critical CHD

Answer 2

Requiring surgery or catheter - based intervention in first year of life

Question 3

Shunt

Answer 3

Abnormal communication between chambers or blood vessels

Question 4

Malformations caused left to right shunts

Answer 4

Atrial septal defects (ASD)- hole in heart, abnormal opening in dividing wall of Atria (upper chambers)

Ventricular septal defect (VSD) - hole in heart, abnormal opening in dividing wall of ventricles (lower chambers)

Patent ductus ateriosus (PDA) - opening between 2 major blood vessels leading from heart, normal before birth and closes shortly after birth

Question 5

Malformations causing right to left shunts

Answer 5

Tetralogy of fallot

Patent foramen ovale (PFO)

Question 6

Malformations causing an obstruction

Answer 6

Coactation of the aorta

Question 7

Categories of Congenital HD

Answer 7

Based on:
Existence /absence of cyanosis
Increase or decrease in blood flow of pulmonary circulation
Obstruction of blood flow from ventricles

Question 8

Acyanotic category

Answer 8

Increase pulmonary blood flow = atrial septal defect, VSD, PDA, atrioventricular canal

Obstruction of blood flow from ventricles = coactation of aorta, aortic stenosis, pulmonary stenosis

Question 9

Cyantoic category

Answer 9

Decrease pulmonary blood flow - tetralogy of fallot, tricuspid altresia

Mixed blood flow - transposition of great arteries, total anormatous pulmonary venous return, turn us ateriosis, hypoplastic L heart syndrome

Question 10

Etiology of Congenital HD

Answer 10

Sporadic genetic abnormalities are major known causes
Most common genetic cause = trisomy 21
Environmental and maternal factors
Nutritional factors: folate supplementation decrease risk of CHD

Question 11

Left to right shunts

Answer 11

Cause pulmonary volume overload

Chronically increase both volume and pressure in pulmonary circulation

ASD
VSD
PDA

Question 12

Right to left shunts

Answer 12

Bypass lungs leading to hypoxia/cyanosis
Allow venous emboli to enter systemic circulation
Finger and toe chubbing

Question 13

Pathophysiology of Left to Right shunts

Answer 13

Abnormal connection between systemic and pulmonary circulations

The overall clinical effect is recirculation of already oxygenated pulmonary venous blood through pulmonary venous vasculature

Nuerohumoral activation: SNS, renin-angiotensin system

Pulmonary HT: continuous increase of pulmonary artery pressure sometimes becomes systemic

Question 14

Atrial septal defect (ASD)

Answer 14

Left to right

Abnormal fixed openings in atrial septum that allows communication between L and R atria

Most common congenital cardiac abnormality in adults

ASD usually asymptomatic until adulthood

Question 15

Pathophysiology of ASD

Answer 15

Pulmonary vascular resistance is much less than systemic vascular resistance = L to R shunt

Pulmonary and systemic resistances
Compliance of R and L ventricles
Size of defect

Question 16

ASD clinical features

Answer 16

Mummer is often heard as a result of the flow through the pulmonary valve and/or through ASD

ASD closure reverses the blood flow abnormality and prevents complications

Question 17

Ventricular Septal Defect (VSD)

Answer 17

Left to right

Incomplete closure of the ventricular septum causes blood to communicate between L and R ventricles

Most common form of congenital abnormality

Question 18

VSD clinical features

Answer 18

Most VSDs that clinically manifest in children are associated with other congenital cardiac abnormalities such as tetralogy of fallot

Large defects generally cause significant L to R shunting causes early R ventricular hypertrophy and pulmonary HT

Question 19

Patent ductus ateriosus (PDA)

Answer 19

Left to right

Allows blood to flow between aorta and pulmonary artery during fetal development thus bypassing the lungs

Ducts normally close within 1-3 days of life - persistent PDA leads to L to R shunting

Question 20

Clinical implication of PDA

Answer 20

In premature infants is essentially all L to R from aorta into pulmonary arteries

Therefore there is an excessive flow through pulmonary circulation and systemic hypo-perfusion

Question 21

Tetralogy of Fallot (toF)

Answer 21

Right to left

One of the most common congenital heart lesions that needs attention in first year of life

Major pathologic features:
Stenosis of pulmonary artery
intraventricular communication (VSD)
Deviation of origin of aorta to right coverriding aorta 
Concentric R ventricular hypertrophy

Question 22

Clinical features ToF

Answer 22

If left untreated patients can survive into adult life

Symptom severity related to extent of pulmonary stenosis

Question 23

Patent foramen ovale

Answer 23

Foramen ovale= small hole resulting from defective post nasal closure of flap

It closes prematurely in approx 80% of people by 2 years old

Unsealed flap can open if R sided pressures become elevated and cause paradoxical embolism

Question 24

Coarctation of the aorta

Answer 24

Obstructive congenital abnormality

Constriction of aorta

Pathogenesis:
Congenital: genetic predisposition in families, may be associated with Turners Syndrome
Acquired: due to inflammatory disease of the aorta

Question 25

Clinical manifestations of coarctation of aorta

Answer 25

Depends on severity of the narrowing and the PDA

HT in upper extremities with weak pulses and hypotension in lower extremities causing claudication and coldness