Congential Heart Disease Flashcards
How common is congenital heart disease?
Common Incidence of 6-8 per 1000 births
What is the most common type of congenital heart defect?
Ventricular septal defects
What is the second most common type of congenital heart disease?
Atrial septal defects
What happens in transposition of the great vessels?
The septum that forms in truncus anteriosus does not take spiral course, meaning that the great vessels are not connected to the correct chambers
What is the Tetralogy of Fallot?
A group of 4 lesions occurring together
What is the Tetralogy of Fallot a result of?
A single development defect
What does Tetralogy of Fallot do?
Places the outflow portion of interventricular septum too far in anterior and cephalad directions
What can cause CHD?
Genetics
Environment
Maternal infections
What environmental factors can cause CHD?
Tetragenicity from drugs, alcohol etc
Give two examples of maternal infections that can cause CHS?
Rubella
Toxoplasmosis
What does a left to right hunt require?
A hole
What happens when there is a left to right shunt?
Blood from left heart returns to the lungs instead of going to the body
Is increased lung blood flow damaging?
Not by itself
What is the problem with a left to right shunt?
Increased pulmonary artery or pulmonary venous pressure can be damaging
What does a right to left shunt require?
A hole and distal obstruction
What is the problem with a right to left shunt?
Deoxygenated blood bypasses the lungs
What is an acyanotic heart defects?
Defects that do not result in a lower than normal concentration of oxygen in the blood
Give 5 acyanotic heart defects
Atrial septal defect Patent Foramen Ovale Ventricular septum defect Patent Ductus Arteriosus Coarctation of Aorta
What is an atrial septal defect?
An opening in the septum between two atria that persists following birth
What is the incidence of atrial septal defects?
67 in 100,000 live births
What does the foramen ovale do?
It exists prenatally to permit right to left shunting of oxygenated blood
What is the foramen ovale designed to do?
Close promptly after birth
What does failure of the foramen ovale to close allow?
Blood to continue to flow between the two atria postnatally
In what direction is flow when there is an atrial septal defect?
Mainly from left to right
Why is the flow mainly from left to right when there is an atrial septal defect?
Because left atrial pressure is greater than right atrial pressure
What is the result of the flow mainly being from left to right when there is an atrial septal defect?
There is no mixing of deoxygenated blood with oxygenated blood being pumped around the circulation
Where do ASD’s occur?
Almost anywhere along the septum
What is the most common site for ASDs?
The foramen ovale
What is it called when the atrial septal defect is at the foramen ovale?
An ostium secundum ASD
Where does an ostium primum ASD occur?
At the inferior part of the septum
What are the haemodynamic effects of ASD’s?
Increased pulmonary blood flow
What is the result of an increased pulmonary blood flow?
Right ventricular volume overload, leading to eventual right heart failure
Is a patent foramen ovale a true ASD?
No
What is the prevalence of a patent foramen ovale?
May be present in ~20% of the population
What is the result of a patent foramen ovale?
Generally, clinically silent
Why is a patent foramen ovale generally clinically silent?
Since higher left atrial pressure causes functional closure of the flap valve
How can a patent forman ovale cause problems?
It may be a route by which venous embolism reaches the systemic circulation, if the pressure on the right side of the heart increases even transiently
What is it called when a patent foreman ovale causes a venous embolism in the systemic circulation?
A paradoxical embolism
What is a ventricular septum defect?
An opening in the interventricular septum
Where can a ventricular septum defect occur?
At any point
Where does a ventricular septum defect most commonly occur?
In the membranous portion of the septum
What are the haemodynamic effects of a ventricular septum defect?
Left to right shunt
Why does a ventricular septum defect cause a left to right shunt?
Because the left ventricular pressure is much higher than the right
What is the result of the left to right shunt?
Left ventricular volume overload, causing pulmonary venous congestion
What does pulmonary venous congestion eventually lead to?
Pulmonary hypertension
What is the ductus arteriosus?
A vessel that exists in the foetus to shunt blood from pulmonary artery to aorta before lungs are functional
What should happen to the ductus arteriosus shortly after birth?
It should close
Why does the ductus arteriosus close shortly after birth?
As pressure in the pulmonary artery drops following perfusion of lungs
What does failure of the ductus arteriosus to close cause?
Patent ductus arteriosus
In what direction would blood flow through the ductus arteriosus after birth?
From the aorta to the pulmonary artery
Why would blood flow from the aorta to the pulmonary artery if the ductus arteriosus remained open after birth?
Because its going from a high pressure to a low pressure
What is heard when the ductus arteriosus is patent?
A mechanical murmur is heard constantly throughout systole/diastole
Why can a mechanical murmur be heard when there is a patent ductus arteriosus?
Because pressure in the aorta is always greater than in the pulmonary artery
Does left to right shunting of blood cause cyanosis?
No
What does the extend of the problem caused by a patent ductus arteriosus depend on?
The degree of shunting
What does chronic left to right shunting lead to?
Vascular remodelling of pulmonary circulation, and an increase in pulmonary resistance
What happens if the pulmonary circulation increases beyond that of the systemic circulation due to a patent ductus arteriosus?
The shunt will reverse direction
What is it called when the shunt caused by a patent ductus arteriosus reverses direction?
Eisenmeger syndrome
What is coarction of the aorta?
Narrowing of the aortic lumen in the region of the liganentum arteriosum
What makes up the liganentum arteriosum?
The former ductus arteriosus
What may coarction of the aorta lead to?
An increase in afterload on the left ventricle
What does an increase in afterload on the left ventricle lead to?
Left ventricular hypertrophy
What is the effect of a coarctation of the aorta?
Blood flow to the body is reduced
Where is blood flow not reduced when there is a coarctation of the aorta?
The head and upper limb
Why is the blood supply to the head and upper limb not affected when there is coarctation of the aorta?
Because the vessels to these areas usually emerge proximal to coarctation
What does extent of the symptoms of coarctation of the aorta depend on?
The severity of the coarctation
What may happen with severe coarctation of the aorta?
Infant may present with symptoms of heart failure shortly after birth
What may happen in mild cases of coarctation of the aorta?
Defect may be detected in adult life
What are the symptoms of coarctation of aorta?
Femoral pulses weak and delayed
Upper body hypertension
Give 4 cyanotic heart defects?
Tetralogy of Fallot
Tricuspid Atresia
Transposition of the great arteries
Hypoplastic left heart
What is Tetralogy of Fallot?
A group of 4 lesions occuring together as a result of a single developmental defect placing outflow portions of the interventricular septum too far in anterior and cephalad directions
What are the 4 abnormalities in Tetralogy of Fallot?
VSD
Overriding aorta
Pulmonary stenosis
Right ventricular hypertrophy
To what degree are pulmonary stenosis and right ventricular hypertrophy present in Tetralogy of Fallot?
Variable
What does pulmonary stenosis cause?
Persistance of foetal right ventricular hypertrophy
Why does pulmonary stenosis cause right ventricular hypertrophy?
As the right ventricle must operate at a much higher pressure to pump blood through the pulmonary artery
What aspects of the Tetralogy of Fallot allow right to left shunting?
Increased pressure on the right side of the heart
VSD
Overriding aorta
What is the result of right to left shunting?
A mix of deoxygenated blood with oxygenated blood going into the systemic circulation, resulting in cyanosis
What does the magnitude of the shunt and the severity in Tetralogy of Fallot depend on?
The severity of pulmonary stenosis
When does Tetralogy of Fallot present?
May present in infancy
Mild cases can present in adulthood
What is Tricuspid Atresia?
Lack of development of tricuspid valve
What is the problem with tricuspid atresia?
It leaves no inlet to the right ventricle
What must be present in tricuspid atresia?
A complete right to left shunt of all blood returning to the right atrium (ASD or PFO) and a VSD or PDA to allow blood flow to the lungs- there needs to be a right to left shunt of the entire venous return
What does transposition of the great arteries result in?
Two unconnected parallel circulations, instead of two in series
What has happened in transposition of the great arteries?
The right ventricle is connected to aorta and the left ventricle to pulmonary trunk
What is the prognosis for a patient with transposition of the great arteries?
Condition not compatible with life after birth, unless a shunt exists to allow to two circulations to communicate
How can a patient with transposition of the great arteries be treated?
A shunt must be maintained, or created immediately following birth to sustain life until surgical correction can be made
What shunt can allow a patient with transposition of great arteries to survive until after birth?
Ductus arteriosus can be maintained patent and/or an atrial septal defect formed
What happens in hypoplastic left heart?
The left ventricle and ascending aorta fail to develop properly, meaning the ascending aorta is very small
What must happen when there is a hypoplastic left heart?
The right ventricle supports systemic circulation
What is also present with hypoplastic left heart?
PFO or ASD
What supplies the systemic circulation with hypolastic left heart?
Via a PDA
What happens if a hypoplastic left heart is not surgically corrected?
It is lethal
