Congenital Heart Defects

Question 1

What is the basic pathophysiology associated with heart

Answer 1

It boils down to 6: 1. Pump failure (MI, CHF) 2. Flow obstruction (stenosis) 3. Regurgitant flow (incompetent valve) 4. Shunted flow 5. Disorders of cardiac conduction 6. Rupture of the heart or connected vessel

Question 2

3 major pathophysiological conditions of congenital heart defects

Answer 2

1. Left to right shunt, blood from the left side of the heart goes into the right side of the heart, increasing pulmonary blood flow. This can lead to pulmonary hypertension, has a worse prognosis than cancer. Eg are ASD, VSD and PDA
2. Right to left flow: causes cyanosis which makes it clinically easy to diagnose this form of congenital anomaly. Examples are Tetralogy of Fallot (TOF) and transposition of great arteries
3. Obstruction: Coarctation of aorta and valvular stenosis

Question 3

What are VSD, ASD and PDA

Answer 3

Question 4

What are 2 syndromes associated with congential heart defects (CHD)

Answer 4

diGeorge and Down’s syndrome

Question 5

What are the reasons for CHD

Answer 5

1. Trisomy 21 is the most common cause of CHD
2. There are also environmental causes such as rubella and gestational diabetes
3. Greatest risk factor is if the parent has a congenital heart defect or a brother then the patient will have it too

Question 6

Ventricular Septal Defect

Answer 6

1. Most common, happens 40% of the time in CHD cases
2. Isolated or could be part of the Tetralogy of Fallot, membranous ones are part of the syndromes
3. Could be muscular or membranous defect, the muscular defect close by themselves 50% of the time whereas the membraneous defects stay
4. Muscular defects are tiny, membranous ones are bigger usually

Question 7

Answer 7

VSD

Question 8

Answer 8

VSD of the membrane

Question 9

What happens when there is a left to right shunt

Answer 9

It leads to pulmonary hypertension and this is the most important thing to understand in this entire lecture

Question 10

Important things to know about the heart murmur

Answer 10

1. Murmor is often not heard at birth
2. Big defects do not produce a murmor since there is no turbulent flow of blood
3. Murmurs get louder when the musclar ventral septal defects begins to close
4. Babies with VSD have high pulmonic blood flow and they show signs of CHF
5. Most important clinical symptom of a baby with CHD is failure to thrive

Question 11

What happens when babies with large VSD remain untreated

Answer 11

They develop what we call the Eisenmenger syndrome or the Eisenmenger pathophysiology:

1. Increased blood flow to the lungs causes pulmonic hypertension
2. Blood vessels in the lung responds by shunting the vessels which causes hypertrophy of the smooth muscles
3. Eventually the pulmonic pressure gets high enough that there is shunt reversal, blood starts to flow back to the heart
4. This leads to cyanosis and eventual death

Question 12

What is the cure for Eisenmenger syndrome

Answer 12

Combined heart and lung transplant

Question 13

Atrial Septal Defect types

Answer 13

It has 3 types:

1. ASD secundum type - defects of fossa ovalis (big hole in the atria and its oval), most common, 90% of the time
2. ASD primum type - involves valves, adjacent of AV valves, associated with claft anterior mitral leaflet
3. ASD of the sinus venosus type - near the entrance of the vena cava

Question 14

ASD

Answer 14

1. Can be asymptomatic until the age of 30
2. Can have a murmur due to turbulent blood flow
3. Irreversible pulmonary hypertension is rare
4. Low mortality
5. unassociated with other anomalies except for septum primum type which is associated with mitral and tricuspid anomalies

Question 15

Tetralogy of Fallot

Answer 15

1. VSD
2. Pulmonic stenosis in the RV outflow tract and the pulmonic valve
3. Dextro-position of the aorta, overiding both the ventricles
4. Hypertrophy of the right ventricle - they absolutely get pulmonary hypertension

Clinically pulmonary stenosis is the most severe. This disease was not treatable 30 or so years ago

Question 16

Know how the 4 previosuly described pathologies look like

Answer 16

Question 17

Answer 17

Tetralogy of Fallot

Question 18

Answer 18

Boot shape of the heart due to Tetralogy of Fallot

Question 19

Clinical features of Tetralogy of Fallot

Answer 19

1. Patients often present with cyanosis. They also have patent ductus arteriosis which closes in the first few days of their birth which makes cyanosis worse - we dont want this to happen so we give them prostaglandin
2. Loud murmur
3. Tetralogy spell - sudden constriction of blood outflow to the lungs which causes more severe cyanosis

Question 20

How do you diagnose Tetralogy of Fallot

Answer 20

1. Perform the hypoxia test: if they have a pulmonary disease like low surfactant levels and we give them oxygen, the cyanosis improves but in case of Tetralogy of Fallot it doesnt get any better.
2. Performing an echocardiogram by the pediatric cardiologist would then be used to accurately diagnose Tetralogy of Fallot

Question 21

What is the most common cyanotic CHD

Answer 21

Tetralogy of Fallot

Question 22

What determines the clinical severity of Tetralogy of Fallot

Answer 22

The extend of pulmonary stenosis

Question 23

WMBU about Tetralogy of Fallot

Answer 23

1. Cyanosis soon after birth
2. Clubbing of the fingers
3. Patent Ductus Arteriosis provides additional lumen to compensate for pulmonary stenosis
4. Tet spells
5. Failure to thrive
6. Mortality is high without surgery

Question 24

Answer 24

Transposition of the great arteries, the pulmonic artery and aorta have switched places and now aorta recived deoxygenated blood that it supplies to the rest of the body. This is fatal without surgery

Question 25

Clinical facts about transposition of the great vessels

Answer 25

1. Severe cyanosis shortly after birth, can also be diagnosed before birth
2. PDA provides some mixing but when it closes there is a big problem since deoxygenated blood goes to the rest of the body

Question 26

How do you treat transposition of the great vessels

Answer 26

1. Hypoxia test/Eco
2. Give prostaglandin to keep the duct open
3. A temporary solution is to do balloon atrial septostomy where there is enlarging of the foreman ovale (essentially creating an ASD) to improve mixing
4. Surgical correction is always required

Question 27

Patent Ducus Arteriosis

Answer 27

1. Results in elevated pulmonic resistance
2. Right to left shunt - hypoxemic blood is transfered from PA to the aorta
3. Cyanosis
4. Clubbing of the toes and not the fingers

Question 28

Answer 28

Patent Ductus Arteriosis

Question 29

WMBU about PDA

Answer 29

1. Normally present during birth, closes within 2 to 3 days
2. Present in premature babies
3. When detected indomethacin is given to induce closure as it inhibits prostaglandin
4. It has a machinery murmur
5. May be associated with other CHD

Question 30

Coarctation of the aorta

Answer 30

1. Obstruction of the aorta, hypertension in upper parts of the body, hypotension in lower parts of the body
2. Very loud heart murmur
3. Notching of the ribs - arteries press on the ribs due to high pressure, in a growing child this puts pressure on the ribs which causes the notching effect, see the slide
4. Can be with a PDA or without a PDA

Question 31

Answer 31

Notching on the ribs

Question 32

Mnemonic