Paediatrics - Cardiology Flashcards
KEY What is a cyanotic heart disease (pathophysiology)
Examples of heart defects that can cause cyanotic heart disease? 5
What is Eisenmenger syndrome?
Cyanosis occurs when deoxygenated blood enters the systemic circulation. Cyanotic heart disease occurs when blood is able to bypass the pulmonary circulation and the lungs. This occurs across a right-to-left shunt. A right-to-left shunt describes any defect that allows blood to flow from the right side of the heart (the deoxygenated blood returning from the body) to the left side of the heart (the blood exiting the heart into the systemic circulation) without travelling through the lungs to get oxygenated.
Heart defects that can cause a right-to-left shunt, and therefore cyanotic heart disease, are:
Ventricular septal defect (VSD)
Atrial septal defect (ASD)
Patent ductus arteriosus (PDA)
Transposition of the great arteries
Tetrallogy of fallot
**Transpoition and Tetrallogy of fallot are actually cynatic from birth, the other three just might evenutally caus eisenmenger. **
Patients with a VSD, ASD or PDA are usually not cyanotic. This is because the pressure in the left side of the heart is much greater than the right side, and blood will flow from the area of high pressure to the area of low pressure. This prevents a right-to-left shunt. If the pulmonary pressure increases beyond the systemic pressure blood will start to flow from right-to-left across the defect, causing cyanosis. This is called Eisenmenger syndrome.
Patients with transposition of the great arteries will always have cyanosis because the right side of the heart pumps blood directly into the aorta and systemic circulation.
It is really important to understand the fetal circulation. This will help you to understand the changes that happen in a baby at birth, the circulation of a newborn baby and the causes of murmurs in babies and young children.
Function of the umbilical vessels?
What is the purpose of the 3 fetal shunts and what are they?
What happens at birth? Pressures?
This first bit is me.
Purpose of the fetal heart isn’t just to pump oxygenated blood around the body, it is also to pump semi-deoxygenated blood (from the IVCs) back to the placenta. The 2 umbilical arteries branch off of the internal iliac arteries and carry deoxygenated blood to the palcenta for exchange. The umbilican vein delivers oxygenated blood from the placenta to the portal vein.
The 3 Fetal Shunts
Ductus venosus: This shunt connects the umbilical vein to the inferior vena cava and allows blood to bypass the liver. (me - bypass the portal vein so that oxygen-rich shunted to the other organs)
Foramen ovale: This shunt connects the right atrium with the left atrium and allows blood to bypass the right ventricle and pulmonary circulation.
Ductus arteriosus. This shunt connects the pulmonary artery with the aorta and allows blood to bypass the pulmonary circulation.
At Birth
In the fetus, the pulmonary vascular resitance is high because the alveola are closed (not space for vessels). Blood shunts from right to left - through the ductus arteriosus and the foramen ovale. The first breaths the baby takes expands the alveoli, decreasing the pulmonary vascular resistance. The decrease in pulmonary vascular resistance causes a fall in pressure in the right atrium. At this point the left atrial pressure is greater than the right atrial pressure, which squashes the atrial septum to cause functional closure of the foramen ovale, similar to a closed valve with nothing flowing through it. This then gets sealed shut structurally after a few weeks and becomes the fossa ovalis.
Prostaglandins are required to keep the ductus arteriosus open. Increased blood oxygenation causes a drop in circulating prostaglandins. This causes closure of the ductus arteriosus, which becomes the ligamentum arteriosum.
Immediately after birth the ductus venosus stops functioning because the umbilical cord is clamped and there is no flow in the umbilical veins. The ductus venosus structurally closes a few days later and becomes the ligamentum venosum.
What are flow murmurs in children?
KEY - this came up
Innocent murmurs are also known as flow murmurs. They are very common in children. They are caused by fast blood flow through various areas of the heart during systole.
Innocent murmurs have typical features, all beginning with S:
Soft
Short
Systolic - me note that a lot of pathological murmurs are also systolic
Symptomless
Situation dependent, particularly if the murmur gets quieter with standing or only appears when the child is unwell or feverish
Clear innocent murmurs with no concerning features may not require any investigations - THIS IS WHAT THEY TESTED. Features that would prompt further investigations and referral to a paediatric cardiologist would be:
Murmur louder than 2/6
Diastolic murmurs
Louder on standing
Other symptoms such as failure to thrive, feeding difficulty, cyanosis or shortness of breath
Investigations for heart murmurs
The key investigations to establish the cause of a murmur and rule out abnormalities in a child are:
ECG
Chest Xray
Echocardiography
What is a ventricular septal defect?
common causes?
pathophysiology:
- cyanotic or acynotic?
- why do symptoms occour and when do they appear?
- what symptoms occour?
- when does it become cyanotic
The most common congenital heart defect
A ventricular septal defect (VSD) is a congenital hole in the septum (wall) between the two ventricles. This can vary in size from tiny to the entire septum, forming one large ventricle. VSDs can occur in isolation, however there is often an underlying genetic condition and they are commonly associated with Down’s Syndrome (partiuclarly AVSDs) and Turner’s Syndrome.
Pathophysiology:
Due to increased pressure blood there is a L to R shunt, which causes increased blood flow to the lungs.
Therefore intially VSD are acyanotic because the blood still gets oxygenated in the lungs before flowing round the body (no L to R shunt).
Symptoms appear when the pulmonary vascular reistance has fallen (continously decreases after birth) and a large volume is shunted into to the right side.
Sx- tachypnea, poor feeding and failure to thrive.
This is because there is pulmonary oedema from the increase blood that is shunted over. And when babies feed they have to hold their breath and exert themselves - they cant manage this when they have extra fluid in the lungs. left to right shunt leads to right sided overload, right heart failure and increased flow into the pulmonary vessels.
Over time:
The extra blood flowing through the right ventricle increases the pressure in the pulmonary vessels over time, causing pulmonary hypertension. If this continues, the pressure in the right side of the heart may become greater than the left, resulting in the blood being shunted from right to left and avoiding the lungs. When this happens the patient will become cyanotic because blood is bypassing the lungs. This is called Eisenmenger Syndrome.
symptoms of a ventricular septal defect?
Examination findings?
Treatment?
Key complication?
Presentation
Often VSDs are initially symptomless and patients can present as late as adulthood. They may be picked up on antenatal scans or when a murmur is heard during the newborn baby check.
Typical symptoms include:
Poor feeding
Dyspnoea
Tachypnoea
Failure to thrive
Examination Findings - Patients with a VSD typically have a pan-systolic murmur
Treatment - similar to ASD!
Treatment should be coordinated by a paediatric cardiologist:
- watchful waiting - small VSDs with no symptoms or evidence of pulmonary hypertension or heart failure can be watched over time. Often they close spontaneously.
- surgical correction using a transvenous catheter closure via the femoral vein or open heart surgery.
There is an increased risk of infective endocarditis in patients with a VSD. Antibiotic prophylaxis should be considered during surgical procedures to reduce the risk of developing infective endocarditis.
What is an Atrial Septal Defect (ADS)?
Atrial septal defect a cyanotic heart disease? Direction of typical shunt?
Key - when do symptoms occour?
what is eisenmenger syndrome?
3 types of ASD?
Second most common CH defect.
An atrial septal defect is a defect (a hole) in the septum (the wall) between the two atria. This connects the right and left atria allowing blood to flow between them. The atrial septum forms from the fusion of two walls, the septum primum and the septum secondum
An atrial septal defect leads to a shunt, with blood moving between the two atria. Blood moves from the left atrium to the right atrium because the pressure in the left atrium is higher than the pressure in the right atrium. This means blood continues to flow to the pulmonary vessels and lungs to get oxygenated and the patient does not become cyanotic.
KEY - FROM THE LECTURE:
Unlike VSD, ASDs rarely present in childhood with Sx (just a murmur) but if they are not closed then overtime they cause problems in older children and adults. Slightly different to Z2F
If untreated ASD can gradually lead to increased blood flow to the lungs, which eventually (years later i think) may result in pulmonary hypertension and eventually Eisenmenger syndrome. This is where the pulmonary pressure is greater than the systemic pressure, the shunt reverses and forms a right to left shunt across the ASD, blood bypasses the lungs and the patient becomes cyanotic.
3 Types:
Ostium secondum, where the septum secondum fails to fully close, leaving a hole in the wall.
Patent foramen ovale, where the foramen ovale fails to close (although this not strictly classified as an ASD).
Ostium primum, where the septum primum fails to fully close, leaving a hole in the wall. This tends to lead to atrioventricular valve defects making it an atrioventricular septal defect.
Complications of atrial septal defects - 4
- Stroke in the context of venous thromboembolism (see below)
- Atrial fibrillation or atrial flutter - if not closed the increased blood shunting to the right side causes dilitation of the right atrium and therefore the SAN.
- Pulmonary hypertension and right sided heart failure
- Eisenmenger syndrome
TOM TIP: It is worth remembering atrial septal defects as a cause of stroke in patients with a DVT. Normally when patients have a DVT and this becomes an embolus, the clot travels to the right side of the heart, enters the lungs and becomes a pulmonary embolism. In patients with an ASD the clot is able to travel from the right atrium to the left atrium across the ASD. This means the clot can travel to the left ventricle, aorta and up to the brain, causing a large stroke. An exam question may feature a patient with a DVT that develops a large stroke and the challenge is to identify that they have had a lifelong asymptomatic ASD. OMG James’s PE colleague had a DVT-> stroke!
Atrial Septal Defects:
Murmur? 2
How do they present?
Management? 2
Presentation:
- mid-systolic crescendo-decrescendo murmur - (systolic makes sense tbf)
- split second heart sound (increase volume in right side delays the closure of the Pulmonary valve)
Unlike VSD, often Asx in childhood. Typical symptoms in childhood (i think larger defects) are:
Shortness of breath
Difficulty feeding
Poor weight gain
Lower respiratory tract infections
Management:
small and asymptomatic ADS: watching and waiting can be appropriate. DOACs for adults to prevent stroke.
Symptomatic ASDs: transvenous catheter closure (via the femoral vein) or open heart surgery.
What is patent ductus arteriosus?
one key risk factor?
murmur?
Does PDA cause Symptoms? Why?
When the ductus arteriosus fails to close after birth.
Usually, the ductus arteriosus normally stops functioning within 1-3 days of birth, and closes completely within the first 2-3 weeks of life. The reasons why it fails to close are unclear, but it may be genetic or related to maternal infections such as rubella. Prematurity is a key risk factor - preterm infants have higher levels of prostaglandins which keeps it open
A small PDA can be asymptomatic, cause no functional problems and close spontaneously. Occasionally patients can remain asymptomatic throughout childhood and present in adulthood with signs of heart failure.
Murmur: a continuous crescendo-decrescendo “machinery” murmur.
Symptoms:
Yes like VSD, PDA presents with SOB, poor feeding, failure to thrive.
Explaination:
The pressure in the aorta is higher than that in the pulmonary vessels, so blood flows from the aorta to the pulmonary artery. This creates a left to right shunt where blood from the left side of the heart crosses to the circulation from the right side. This increases the pressure in the pulmonary vessels causing pulmonary hypertension, leading to right sided heart strain as the right ventricle struggles to contract against the increased resistance. Pulmonary hypertension and right sided heart strain lead to right ventricular hypertrophy. The increased blood flowing through the pulmonary vessels and returning to the left side of the heart leads to left ventricular hypertrophy.
PDA card 2:
Investigation?
Management?
Ix - Echo
The diagnosis of PDA can be confirmed by echocardiogram. The use of doppler flow studies during the echo can assess the size and characteristics of the left to right shunt. An echo is also useful for assessing the effects of the PDA on the heart, for example demonstrating hypertrophy of the right ventricle, left ventricle or both.
Mangement:
Patients are typically monitored until 1 year of age using echocardiograms - small PDAs can close spontanouesly. After 1 year of age it is highly unlikely that the PDA will close spontaneously and trans-venous catheter or surgical closure can be performed. Symptomatic patient or those with evidence of heart failure as a result of PDA are treated earlier.
A small card on Atrioventricular Septal defect (AVSD):
- key risk factor?
- presentation?
Common in Down’s sydrome (Trisomy 21)
Can lead to pulmonary hypertension more rapidly so all children with Down’s syndrome are screen for AVSD.
Similar symptoms to an VSD with poor feeding ,failure to thrive, tachypnoea
Also leads to hepatomegaly, oedema (just like ASD, VSD, PDA)
Paediatric Heart murmurs - outline the different types?
Atrial Septal Defect:
- Fixed Splitting of the second heart sound is where you hear the closure of the aortic and pulmonary valves at slightly different times because of increased blood on the right side.
- mid-systolic, crescendo-decrescendo
Ventricular Septal Defect:
- pan-systolic murmur
Patent Ductus arteriosus:
- continuous crescendo-decrescendo “machinery” murmur
Tetrallogy of fallot:
- Ejection systolic murmur heard loudest in the pulmonary area - due to pulmonary stenosis, ignore the VSD
Co-artation of the aorta:
- There may be a systolic murmur below the left clavicle
Splitting of the second heart sound:
- When the pulmonary valve closes slightly later than the aortic valve.
- Can be normal on inspiration, but if fixed (also present in expiration) then it is a sign of an ASD
What three underlying lesions can result in eisenmenger syndrome?
Pathophysiology?
How does cyanosis affect the blood?
Management? - 6
Eisenmenger syndrome occurs when blood flows from the right side of the heart to the left across a structural heart lesion, bypassing the lungs. There are three underlying lesions that can result in Eisenmenger syndrome:
Atrial septal defect
Ventricular septal defect
Patent ductus arteriosus
Transpisotion of the great vessels is the other cause of cyanotic heart disease but it doesnt cause a right to left shunt.
Eisenmenger syndrome can develop after 1-2 years with large shunts or in adulthood with small shunts. It can develop more quickly during pregnancy, so women with a history of having a “hole in the heart” need an echo and close monitoring by a cardiologist during pregnancy.
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Normally when there is a septal defect blood will flow from the left side of the heart to the right. This is because the pressure in the left side is greater than in the right. This means blood still travels to the lungs and gets oxygenated, so the patient does not become cyanotic.
Over time the extra blood flowing into the right side of the heart and the lungs increases the pressure in the pulmonary vessels. This leads to pulmonary hypertension. When the pulmonary pressure exceeds the systemic pressure, blood begins to flow from the right side of the heart to the left across the septal defect. This is a right to left shunt. Essentially it becomes easier for the right side of the heart to pump blood across the defect into the left side of the heart compared with pumping blood into the lungs. This causes deoxygenated blood to bypass the lungs and enter the body. This causes cyanosis.
Cyanosis refers to the blue discolouration of skin relating to a low level of oxygen saturation in the blood. The bone marrow will respond to low oxygen saturations by producing more red blood cells and haemoglobin to increase the oxygen carrying capacity of the blood. This leads to polycythaemia, which is a high concentration of haemoglobin in the blood. Polycythaemia gives patients a plethoric complexion. A high concentration of red blood cells and haemoglobin make the blood more viscous, making patients more prone to developing blood clots.
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Eisenmenger syndrome reduces life expectancy by around 20 years compared with healthy individuals. The main causes of death are heart failure, infection, thromboembolism and haemorrhage. The mortality can be up to 50% in pregnancy.
MANAGEMENT
Ideally the underlying defect should be managed optimally or corrected surgically to prevent the development of Eisenmenger syndrome.
Once the pulmonary pressure is high enough to cause the syndrome, it is not possible to medically reverse the condition. The only definitive treatment is a heart-lung transplant, however this has a high mortality.
Patients with Eisenmenger syndrome will be closely followed up by a specialist. Medical management involves:
Oxygen can help manage symptoms but does not affect overall outcomes
Treatment of pulmonary hypertension, for example using sildenafil
Treatment of arrhythmias
Treatment of polycythaemia with venesection
Prevention and treatment of thrombosis with anticoagulation
Prevention of infective endocarditis using prophylactic antibiotics
What condition is coartation of the aorta often associated with?
cyanotic or acyanotic?
presentation? 3 things i think!
management? - 2 scenarios
Coarctation of the aorta is a congenital condition where there is narrowing of the aortic arch, usually around the ductus arteriosus. The severity of the coarctation (or narrowing) can vary from mild to severe. It is often associated with an underlying genetic condition, particularly Turners syndrome.
It is non cyanotic but narrowing of the aorta reduces the pressure of blood flowing to the arteries that are distal to the narrowing. It increases the pressure in areas proximal to the narrowing, such as the heart and the first three branches of the aorta. (Brachiocephalic, Left common carotid, left subclavian)
Presentation:
- weak femoral pulses - four limb blood pressure gradient, lecturer stressed this!
- systolic murmour
- tachypnoea and increased work of breading
- poor feeding - me: pulomnary congestion due to reduced left outflow.
- grey and floppy baby (no blood flow distal to the coartation)
LESS IMPORTANT: Additional signs may develop over time:
- Left ventricular heave due to left ventricular hypertrophy
- Underdeveloped left arm where there is reduced flow to the left subclavian artery or Underdevelopment of the legs
ME UNDERSTADNING:
coartation is causing congestion in the heart and the lungs because of the increased resitance and this makes them tachypneic. PDA helps because even tho the blood is deogenated, it helps because mixes a bit around the coartcaton, some flow is better than no flow to the tissue distal to the coartation. Also Sx may not devolop until 2/3 days of life when the PDA closes.
Management:
- asymptomatic - no intervention required
- severe cases - emergency surgery after birth and Postroglandin E while waiting for surgery to maintian the ductus arteriosis (allows some blood flow flow through the ductus arteriosus into the systemic circulation distal to the coarctation). The PDA is then closed during the surgery.
