Congenital heart disease Flashcards
What is meant by congenital heart disease?
A gross structural abnormality of the heart or intra-thoracic great vessels that is actually or potentially of functional significance
When is antenatal screening performed?
Between weeks 18 and 22 of gestation
What is performed in antenatal screening?
An ultrasound allowing the 4 chambers of the heart and the outflow tracts to be examined
What measurements are taken in antenatal pulse oximetry?
Pre-ductal saturation
Post ductal saturation
What are some examples of cyanotic congenital heart defects?
Hypoplastic left heart syndrome
Tetralogy of Fallot
Transposition of the great vessels
What are some examples of acyanotic congenital heart defects?
Ventricular septal defect
Atrial septal defect
Patent ductus arteriousus
Coarction of the aortic arch
Interruption of the aortic arch
What are the main functions of the placenta in development?
It functions in circulation and gas exchange as well as providing nutritio, waste excretion and homeostasis
Why is there no pulmonary circulation in a foetus?
The lungs are filled with fluid and are unexpanded, meaning that blood doesn’t need to pass through the lungs to receive oxygen
What is the function of the liver and gut in a foetus?
The gut is not in use
The liver plays only a small role in nutrition and waste management
Which blood vessel supplies blood to the foetal heart from the placenta?
Umbilical vein (x1)
Which blood vessel carries blood from the foetal aorta back to placenta?
Umbilical artery (x2)
What are the 3 shunts of foetal circulation?
Ductus venosus
Ductus arteriosus
Foramen ovale
What is the function of the ductus venosus?
This connects the umbilical vein to the inferior vena cava, therefore bypassing the liver and allowing blood flow straight to the foetal heart
What is the function of the ductus arteriosus?
This connects a pulmonary vein branch to the descending aorta, allowing some blood flow from the right ventricle to move directly into the aorta
What is the function of the foramen ovale?
This is an opening between the left and right atria and allows blood to flow straight from the right side of the heart to the left, as the pulmonary circulation is not required
On which side of the heart is the flap of the foramen ovale?
Left
What maintains the patency of the ductus arteriosus?
Prostaglandin E2 which is produced by the placenta
How is blood directed through the foramen ovale?
By the rough wall of the right atrium
What is the average foetal blood saturation level?
70%
What causes the rapid rise in SVR after birth?
The cutting of the umbilical cord causes a rapid increase in vasoconstriction therefore greatly increasing SVR
What causes the rapid decrease in pulmonary vascular resistance after birth?
As the baby breaths and cries, the lungs expand and fill with air
The oxygen tension increases and as oxygen is a potent vasodilator, this causes vasodilation which decreases vascular resistance
What causes closure of the foramen ovale after birth?
The decrease in pulmonary vascular resistance decreases pressure on the right side of the heart
The increase in SVR increases pressure on the left side of the heart
The pressure gradient switches from left to right and so causes closure of the flap on the left side
What causes closure of the ductus arteriosus after birth?
Increased left sided pressure due to increased SVR changes direction of flow
Removal of placenta reduces circulating prostaglandin E2 levels
Oxygen causes contraction of oxygen sensitive muscular layers in the ductus arteriosus
What is formed by closure of the ductus arteriosus?
Ligamentum arteriosus
What is the name of the congenital heart condition in which the ductus arteriosus does not close?
Patent ductus arteriosus
What is the function of the lung fluid in foetal lungs?
This prevents the movement of amniotic fluid into the lungs, which cannot be absorbed
What happens to the fluid in the lungs after birth?
Pregnancy hormones released during labour allow the lungs to take in fluid into their lymphatics and any remaining fluid is removed upon birth by crying and coughing
What type of condition causes collapse at closure of the ductus arteriosus?
Duct dependant conditions
When will most babies with duct dependant conditions collapse?
After 2-7 days
What are some symptoms associated with duct closure in duct dependant conditions?
Severe cyanosis or pallor
Tachypnoea
Distress
Rapid deterioration
Collapse
What is the main treatment option for collapse at duct closure?
Prostaglandin E2 infusions which prevents closure of the ductus arteriosus
What are some examples of duct dependant systemic circulation conditions?
Hypoplastic left heart syndrome
Critical aortic stenosis
Interrupted aortic arch
Critical coarction of the aorta
What are some examples of duct dependant pulmonary circulation conditions?
Tricuspid atresia
Pulmonary atresia
What is the pharmacological treatment option for patent ductus arteriosus?
NSAIDs (e.g. ibuprofen) which interrupt prostaglandin levels, allowing duct closure
What are the surgical options of patent ductus arteriosus?
Surgery to constrict the duct, including clipping or catheter implantation
What is meant by a ventricular septal defect?
Formation of a hole in the intra-ventricular septum
What size of ventricular septal defect is more likely to cause a murmur?
A small septal defect, as this will increase pressure and thus cause more turbulent blood flow
How are ventricular septal defects surgically treated?
Using bypass operations, in which a patch is placed over the defect
What are the risks of patching a ventricular septal defect?
It can obstruct the bundle of His, causing rhythm problems
As the heart grows, it can cause structural abnormalities and valvular defects such as regurgitation
What is persistent pulmonary hypertension of the newborn?
A maintenance of the high pulmonary vascular resistance in newborns, meaning their pulmonary blood pressure is greater than their SVR and thus causing patent foramen ovale and patent ductus arteriosus and therefore causing possible hypoxia
What are some conditions that increase the risk of persistent pulmonary hypertension of the newborn?
Sepsis
Hypoxic ischaemic insult
Meconium aspiration syndrome
Cold stress
What is meconium aspiration syndrome?
This is a condition in which inspiration draws the baby first faecal movements into the lungs
What are some pharmacological treatment options in those with persistent hypertension of the newborn?
Inhaled nitric oxide to cause pulmonary vasodilation to decrease presurre
Adrenaline can also be given to increase SVR
What is the surgical treatment option for persistent hypertension of the newborn?
Extra Corporeal Membrane Oxygenation (ECMO) which is a heart lung bypass surgery
Where is pre-ductal saturation measured?
In the right hand
Where is post-ductal saturation measured?
Left foot
What is meant by an atrio-ventricular septal defect?
A condition in which there is a hole in both the atrial and ventricular septum
Which condition increases the risk of atria-ventricular septal defect?
Trisomy 21 (Down’s syndrome)
What is hypoplastic left heart syndrome?
This is a congenital heart condition resulting in narrowing of the aorta, a small left ventricle and an atrial septal defect, meaning that most blood in the descending aorta comes from the pulmonary artery, via the ductus arteriosus
What is a possible surgical management option for hypoplastic left heart syndrome?
As the atrial septal defect allows some oxygenated blood back into the right side of the heart to reach the aorta via the ductus arteriosus, the defect can be widened via surgery
What is a possible surgical treatment option for hypoplastic left heart syndrome?
Total Cavo-Pulmonary Circulation (TCPC) surgery
This is a 3 step surgery
What is the outcome of Total Cavo-Pulmonary Circulation (TCPC) surgery?
The right ventricle supplies the systemic circulation
The right atrium is connected directly to the pulmonary circulation
The left ventricle is bypassed
What are some complications of total cavo-pulmonary circulation surgery?
It has a high mortality rate
It can lead to early right ventricular failure, so patient may require bypass surgery earlier on in life
What is meant by pulmonary atresia?
Pulmonary atresia is a condition characterised by an unformed pulmonary valve, leading to a narrow or non-existent pulmonary trunk, meaning that blood flow to the lungs is dependant on blood flow from the aorta to the pulmonary arteries via the ductus arteriosus
What are the 4 main components of tetralogy of Fallot?
Narrowing of the pulmonary artery
Large ventricular septal defect
Right ventricular hypertrophy
Pulmonary stenosis
How does tetralogy of Fallot usually present?
A systolic murmur that is loud, harsh, crescendo-dimminuendo and most intense at the left sternal border with possible hypoxic spells
What is meant by transposition of the great vessels?
A condition in which the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle (Vessels swap around)
What other condition allows a baby with transposition of the great vessels to survive?
An atrial septal defect or patent foramen ovale, as this allows some oxygenated blood to enter the aorta and thus reach systemic circulation
How will a baby with transposition of the great vessels present?
Most commonly with severe cyanosis, however, the baby will otherwise not appear to be ill or struggling to breath
What is meant by interruption of the aortic arch?
This is a condition in which the aortic arch narrows, meaning that the descending aortic is mostly supplies by the ductus arteriosus, form the left ventricle
What is meant by coarction of the aortic arch?
This is a condition in which the aorta closes and stops at the arch, meaning the descending aorta is fully supplies by the ductus arteriosus
What is the most common cause of cardiac failure in newborns?
Defects that cause blood to move from the left side of the heart to the right (e.g. patent foramen ovale) as this increases pre-load on the right side of the heart and thus causes dilatation and eventually decreased after load
What are some clinical features of cardiac failure in newborns?
Failure to thrive
Slow/reduced feeding
Breathlessness
Sweatiness
Hepatomegaly
Crepitations
What is meant by palliation in management of congenital heart diseases?
Treatment that restores function to the heart but not normal cardiac anatomy
What is meant by repair in management of congenital heart diseases?
Treatment that restores both function and normal cardiac anatomy
