Cardio Flashcards
How does the fetal circulation work?
Fetus receives oxygen and nutrients and disposes of waste via the placenta, bypassing the lungs
How does the fetal circulation bypass the lungs?
3 fetal shunts
What are the 3 fetal shunts?
Ductus venosus
Foramen ovale
Ductus arteriosus
What does the ductus venosus allow blood to bypass in the fetus?
The liver
What does the ductus venosus connect?
The umbilical vein and inferior vena cava
What does the foramen ovale allow the fetal blood to bypass?
The right ventricle and pulmonary circulation
What does the foramen ovale connect?
The right and left atria
What does the ductus arteriosus allow the fetal circulation to bypass?
The pulmonary circulation
What does the ductus arteriosus connect?
The pulmonary artery and aorta
From the umbilical vein, outline the passage of blood in the fetal circulation:
Placenta–> Umbilical vein–> Ductus venosus–> IVC–> RA–> (Foramen ovale–> Left atrium–> Left ventricle)/ (Right ventricle–> Pulmonary artery–> Ductus arteriosus)–> Aorta–> Internal iliac arteries–> Umbilical arteries–> Placenta
What happens to the pulmonary vascular resistance with the first breath and why?
The first breath expands the alveoli, decreasing the pulmonary vascular resistance
What does the decrease in pulmonary vascular resistance do to the pressure in the right atrium?
Causes it to fall
What does the fall in RA pressure on the first breath result in?
The left atrial pressure becomes greater than the RA, squashing the atrial septum and causing functional closure of the foramen ovale.
Outline the physiology of the closure of the foramen ovale?
On the first breath, the alveoli expand, reducing the pulmonary vascular resistance. This in turn reduces the RA pressure, meaning the LA pressure is greater, squeezing the septum and causing the foramen to close
What does the foramen ovale become after birth and how long does it take to reach this point?
It gets sealed shut after a few weeks to become the fossa ovalis
What causes the closure of the ductus arteriosus at birth?
Increased blood oxygenation causes a drop in circulating prostaglandins which are needed to keep the ductus arteriosus open. This causes its closure.
What does the ductus arteriosus become at birth?
The ligamentum arteriosum
Why does the ductus venosus stop functioning immediately after birth?
Because the umbilical cord is clamped and there is no flow in the umbilical veins
What does the ductus venosum become?
Ligamentum venosum
What are the most common kind of heart murmurs in children?
Innocent murmurs
What are innocent murmurs also known as?
Flow murmurs
What causes flow murmurs?
Fast blood flow through the heart during systole
What are the typical features of innocent murmurs?
Soft Short Systolic Symptomless Situation dependent
How might a situation dependent murmur change?
Quieter on standing
Only appear when the child is unwell/ feverish
What features of a murmur would prompt further investigations and referral to paediatric cardiologist?
Murmur louder than 2/6
Diastolic murmurs
Louder on standing
Other symptoms (e.g. failure to thrice, feeding difficulty, cyanosis, SOB)
What are the key investigations to establish the cause of a murmur and rule out abnormalities?
ECG
CXR
Echo
What is S1?
The first heart sound
What causes S1?
The closing of the atrioventricular valces and the start of ventricular contraction
What are the atrioventricular valves?
Mitral and tricuspid
What is S2?
The second heart sound
What causes S2?
The closing of the semilunar valves
What are the semilunar valves?
Pulmonary and aortic valves
Are S3 and S4 normal?
Always pathological
What are the differentials of a pan-systolic murmur in children?
Mitral regurgitation
Tricuspid regurgitation
Ventricular septal defect
Where would a ventricular septal defect be heard?
Left lower sternal border
What are the differentials of an ejection-systolic murmur in children?
Aortic stenosis
Pulmonary stenosis
Hypertrophic obstructive cardiomyopathy
Where would hypertrophic obstructive cardiomyopathy be heard?
Fourth intercostal space, left sternal border
Where do you listen for the aortic valve?
2nd intercostal space, right sternal border
Where do you listen for the pulmonary valve?
2nd intercostal space, left sternal border
Where do you listen for the tricuspid valve?
5th IC space, left sternal border
Where do you listen for the mitral valve?
5th IC space, midclavicular line
Why is the second heart sound split into two?
Due to the negative intra-thoracic pressure on inspiration, the right side of the heart fills up faster than the left. This increased volume means it takes longer for the right ventricle to empty during systole, causing a delay in the pulmonary valve closing compared to the aortic valve.
What is PDA?
Patent ductus arteriosus
What is the action of the ductus arteriosus?
Shunts blood from the pulmonary artery straight to the aorta, bypassing the lungs
How long after birth should the ductus arteriosus stop functioning and after how long will it close completely?
Stops functioning within 1-3 days
Closes completely in first 2-3 weeks
What are the potential causes of PDA?
Unknown-
Genetic, maternal infections
What is a key risk factor for developing PDA?
Prematurity
Are PDA’s always symptomatic?
No, may be asymptomatic and cause no functional problems and close spontaneously
If patients with PDA are asymptomatic throughout childhood, how may they present in adulthood?
With signs of heart failure
What kind of shunt is created in PDA and why?
Pressure in aorta is higher than pulmonary vessels, so blood flows from left to right side of circulation.
What does the increased pressure in the pulmonary vessels cause?
Pulmonary hypertension, leading to right sided heart strain.
Why do you get right ventricular hypertrophy in PDA?
Due to the pulmonary hypertension causing right sided heart strain
Why do you also get left ventricular hypertrophy in PDA?
Due to the increased blood flowing through the pulmonary vessels and returning to the left side of the heart
How might PDA present?
Murmur at newborn examination SOB Difficulty feeding Poor weight gain LRTI
What kind of murmur might you hear with more severe PDA?
Normal first heart sound, with continuous crescendo-decrescendo ‘machinery’ murmur that may continue during second heart sound
How is a PDA diagnosis confirmed?
Echocardiogram
Doppler flow studies
How is PDA managed?
Patients monitored until 1 year using echo’s.
If not closed, trans-catheter or surgical closure can be performed
Why are patients with PDA monitored for the first year of life?
Because it may spontaneously close itself
What is an atrial septal defect?
Hole in the septum allowing blood to flow between the two atria
What happens to the atria, septum during development of the fetus?
Atria begin connected, then septum primum and septum secondum grow downwards and fuse with endocardial cushion to separate them.
Where is the foramen ovale?
In the second secondum between the atria
What happens to the heart circulation in atrial septal defects?
Blood shunts from the left to right atrium due to the higher pressure in the LA
Does the patient become cyanotic with atrial septal defects?
No, the blood continues to flow to the pulmonary vessels and lungs to get oxygenated
What does the increased flow to the right side of the heart in ASD’s lead to?
Right sided overload
Right heart strain
Can lead to right heart failure and pulmonary hyptersion
What can pulmonary hypertension eventually lead to?
Eisenmenger syndrome
What is Eisenmenger syndrome?
Where the pulmonary pressure is greater than the systemic pressure, so the shunt reverses and forms a right to left shunt across the ASD
What are the different types of atrial septal defect?
Ostium secondum
Patent foramen ovale
Ostium primum
What is the most common ASD?
Ostium secondum
What is ostium secondum
Where the septum secondum fails to close, leaving a hole in the wall
What is ostium primum?
Where the septum primum fails to fully close, leaving a hole in the wall
What does ostium primum usually lead to?
Atrioventricular valve defects
What are the key complications of ASD?
VTE–> Stroke
AF
Pulmonary hypertension–> Right sided heart failure
Eisenmenger syndrome
Why is ASD a cause of stroke in patients with a DVT?
In ASD the clot is able to travel from the right to the left atrium and up to the brain, whereas it would usually cause a pulmonary embolism
What does a murmur sound like in ASD?
Mid-systolic, crescendo-decrescendo murmur, loudest at upper left sternal border, with fixed split second heart sound
What is a fixed split heart sound?
When the split between the aortic and pulmonary valves closing doesn’t change with inspiration or expiration
Why do you get a fixed split heart sound in ASD?
Because blood is flowing from the left atrium to the right atrium, increasing the volume of blood that the right ventricle has to empty before the pulmonary valve can close
When are ASD’s usually picked up?
On antenatal scans or newborn examinations
How may ASD present in childhood?
SOB
Difficulty feeding
Poor weight gain
Lower respiratory tract infections
How may ASD present if asymptomatic in adulthood?
Dyspnoea
Heart failure
Stroke
How do you managed patients with ASD?
Refer to paediatric cardiologist
Either watch or wait or correct surgically with transvenous catheter closure or openheart surgery
What is a ventricular septal defect?
Congenital hole in the septum between the two ventricles
What are VSD’s commonly associated with?
Down’s and Turner’s syndrome
What kind of shunt does a VSD lead to?
Left to right
Do patients become cyanotic with VSD and why?
No, blood still flows to the lungs before entering the rest of the body
What does a left to right shunt lead to?
Right sided overload
Right heart failure
Increased flow to the pulmonary vessels
How do VSD’s usually get picked up?
Antenatal cans
Murmur at newborn baby check
When do VSD’s typically present?
Usually symptomless initially and can present in adulthood
What are typical symptoms of VSD’s?
Poor feeding
Dyspnoea
Tachypnoea
Failure to thrive
What murmur is heard with VSD?
Pan-systolic murmur more prominent at the left lower sternal border, 3/4th intercostal spaces.
How are small VSD’s treated?
watch and wait- often close spontaneously
How are larger/ symptom causing VSD’s treated?
Corrected surgically with transvenous catheter closure or open heart surgery
What does having a VSD increase the risk of?
Infective endocarditis
What is Eisenmenger syndrome?
When blood flows from the right side of the heart to the left across a structural lesion, bypassing the lungs
What are the 3 lesions that can result in Eisenmenger syndrome?
Atrial septal defect
Ventricular septal defect
Patent ductus arteriosus
How long does it take Eisenmengers to develop with large shunts?
1-2 years
How long does it take Eisenmengers to develop with small shunts?
Into adulthood
When might Eisenmenger’s develop more quickly?
During pregnancy so they need close monitoring and an echo
What is the pathophysiology of Eisenmengers?
Septal defect causes a left to right shunt due to increase pressure in left ventricle. However, over time the extra blood flowing into the right side increases the pressure in the pulmonary vessels. When this pressure exceeds the systemic pressure, blood begins to flow from right to left, causing deoxygenated blood to bypass the lungs and enter the body.
What does Eisenmengers cause?
Cyanosis
What is cyanosis?
Blue discolouration of the skin relating to a low oxygen saturation
What does the bone marrow do in response to low oxygen saturations?
Produces more red blood cells and haemoglobin
What does low oxygen saturations lead to?
Polycythaemia
What is polycythaemia?
High concentration of haemoglobin in the blood
What kind of complexion do you get with polycythaemia?
Plethoric- full of fluid
What does polycythaemia increase the risk of?
Blood clots (blood is more viscous)
What is found on examination of Eisenmenger?
Right ventricular heave Loud S2 Raised JVP Peripheral oedema Murmurs associated with underlying septal defect Cyanosis Clubbing Dyspnoea Plethoric complextion
What is a thrill?
Palbable murmur that feels like a vibration
What is a heave?
An abnormally large beating of the heart, usually as a result of right ventricular hypertrophy
Why do you get right ventricular heave with Eisenmenger?
Because the right ventricle has to contract forcefully against the increased pressure in the lungs
Why do you get a loud S2 in Eisenmenger?
Due to the forceful shutting of the pulmonary valve
What is the prognosis of Eisenmenger?
Reduces life expectancy by around 20 years
What are the main causes of death due to Eisenmenger?
Heart failure, infection, thromboemboilsm, haemorrhage
How is Eisenmenger treated?
Manage/ surgically correct underlying defect
Only definitive treatment= heart-lung transpolant
How is Eisenmenger managed?
Oxygen Treatment of pulmonary hypertension Treatment of arrhythmias Venesection for polycythaemia Anticoagulation for thrombosis Prophylactic antibiotics for infective endocarditis
What is coarctation of the aorta?
Congenital condition causing narrowing of the aortic arch
Where is the most common site of narrowing in coarctation of the aorta?
Around the ductus arteriosus
What is coarctation of the aorta often associated with?
An underlying genetic condition (particularly Turners syndrome)
What does narrowing of the aorta do to the blood pressure in the vessels proximal and distal to the narrowing?
Increases the pressure in the proximal areas (heart and aortic branches) and decreases the pressure distally
What is the main indication of coarctation of the aorta in a neonate?
Weak femoral pulses
What will a four limb blood pressure reveal in coarctation of the aorta?
High BP in the limbs supplied from arteries before the narrowing, and low BP in limbs that come after the narrowing
What murmur may be heard in coarctation of the aorta?
Systolic murmur below left clavicle and scapula
What signs may there be of coarctation in infancy?
Tachypnoea
Poor feeding
Grey, floppy baby
What additional signs of coarctation may develop over time?
Left ventricular heave
Underdeveloped left arm
Underdeveloped legs
Does coarctation range in severity?
Yes, may be mild and asymptomatic or severe and require emergency surgery shortly after birth
How is critical coarctation after birth treated?
Prostaglandin E given to keep ductus arteriosus open while waiting for surgery to correct the coarctation and ligate the ductus arteriosus
What is congenital aortic valve stenosis?
When babies are born with a narrow aortic valve
What is the aortic valve made up of?
Three leaflets- the aortic sinuses of the Valsalva
What may happen to the aortic sinuses of Valsalva in aortic stenosis?
They may have an abnormal number of leaflets (1-4)
How may mild aortic stenosis present?
Completely asymptomatic with incidental murmur found on routine examination
How might more severe aortic stenosis present?
With symptoms of fatigue, SOB, dizziness and fainting
When are symptoms of aortic stenosis usually worse?
On exertion
How will severe aortic stenosis present?
With heart failure within months of birth
What are the signs of aortic stenosis on examination?
Murmur Ejection click Palpable thrill Slow rising pulse Narrow pulse pressure
What kind of murmur do you get with aortic stenosis?
Ejection systolic murmur, loudest at aortic area.
What is the character of the aortic stenosis murmur and where might it radiate to?
Cresendo-decrescendo character. Radiates to carotids.
How is aortic stenosis diagnosed?
Echocardiogram
How are patients with congenital aortic stenosis managed?
Regular follow up with paediatric cardiologist
Refular echos, ECGs & excercise testing
What are the treatment options for congenital aortic stenosis?
Percutaneous balloon aortic valvoplasty
Surgical aortic valvotomy
Valve replacement
What are the complications of congenital aortic stenosis?
Left ventricular outflow tract obstruction Heart failure Ventricular arrhythmia Bacterial endocarditis Sudden death
What is the pulmonary valve made up of?
Three leaflets
What is congenital pulmonary valve stenosis?
Abnormal development of the pulmonary valve leaflets, leading them being thickened or fusing and resulting in a narrow opening between the right ventricle and pulmonary artery
What other conditions may pulmonary valve stenosis be associated with?
Tetralogy of Fallot
William syndrome
Noonan syndrome
Congenital rubella syndrome
How does pulmonary valve stenosis present?
Often asymptomatic
How is pulmonary valve stenosis often discovered?
Incidental finding of murmur during routine baby checks
How may more severe pulmonary valve stenosis present?
With symptoms of fatigue on exertion, SOB, dizziness and fainting
What are the signs of pulmonary valve stenosis on examination?
Murmur
Palpable thrill
Right ventricular heave
Raised JVP
What kind of murmur is found with pulmonary valve stenosis?
Ejection systolic murmur, heard loudest at pulmonary area
How is pulmonary valve stenosis diagnosed?
Echocardiogram
How is mild pulmonary valve stenosis managed?
Monitoring with cardiologist- often need no intervention
How is more severe pulmonary valve stenosis managed?
Balloon valvuloplasty via venous catheter
What does balloon valvuloplasty involve?
Inserting catheter into femoral vein undery X-ray guidance, going through IVC and right side of heart to the pulmonary valve and dilating the valve by inflating a balloon
What is Tetralogy of Fallot?
Congenital condition where there are 4 coexisting pathologies
What are the 4 pathologies in Tetralogy of Fallot?
Ventricular septal defect
Overriding aorta
Pulmonary valve stenosis
Right ventricular hypertrophy
What is an overriding aorta?
When the aortic valve is further right than normal, and lies above the VSD.
What does an overriding aorta cause?
A greater proportion deoxygenated blood entering the aorta from the right side of the heart, due to the positioning of the aorta
What further encourages deoxygenated blood through the VSD and into the aorta in tetralogy of fallot?
Pulmonary valve stenosis
Why do you get cyanosis in tetralogy of fallot?
Because the overriding aorta and pulmonary stenosis cause blood to be shunted from right to left, meaning it bypasses the lungs
What happens to the right ventricle in Tetralogy of Fallot?
Right ventricular hypertrophy
What kind of shunt do you get in Tetralogy of Fallot?
Right to left
What are the risk factors for Tetralogy of Fallot?
Rubella infection
Increased age of mother (>40)
Alcohol consumption in pregnancy
Diabetic mother
What is the investigation of choice for diagnosing Tetralogy of Fallot?
Echocardiogram
What can be done during an echo to look at the direction of blood flow?
Doppler flow studies
What may a CXR show in Tetralogy of Fallot?
Boot shaped heart due to right ventricular hypertrophy
When is Tetralogy of Fallot usually picked up?
During antenatal scans
What may be picked up on the newborn baby check that indicates Tetralogy of Fallot?
Ejection systolic murmur caused by pulmonary stenosis
How will severe cases of Tetralogy of Fallot present?
With heart failure before age 1
What are the signs and symptoms of Tetralogy of Fallot?
Cyanosis Clubbing Poor feeding Poor weight gain Ejection systolic murmur Tet spells
What are Tet spells?
Intermittent symptomatic periods where the right to left shunt becomes temporarily worsened, causing a cyanotic episode
What causes Tet spells?
When pulmonary vascular resistance increases or systemic resistance decreases
What are some causes of Tet spells?
Physical exertion
Waking
Crying
Why can physical exertion precipitate a Tet spell?
They will be generating a lot of CO2 which is a vasodilator and therefore reduces systemic vascular resistance. This means blood will be pumped from the right ventricle to the aorta in the path of least resistance.
What will happen to the child during a Tet spell?
They will become irritable, cyanotic and short of breath. May have reduced consciousness, seizures and potentially death
What is the mainstay of treatment for a Tet spell?
Squatting in older children or knees to chest in younger children
Why does a squat position help prevent a Tet spell?
It increases the systemic vascular resistance so encourages blood to enter the pulmonary vessels
What does medical management of a Tet spell involve?
Supplementary oxygen Beta blockers IV fluids Morphine Sodium bicarbonate Phenylephrine
How do IV fluids help in a Tet spell?
Increase pre-load, increasing the volume of blood flowing to the pulmonary vessels
How is Tetralogy of Fallot treated?
Prostaglandin infusion used to maintain the ductus arteriosus, followed by total surgical repair by open heart surgery
What is the prognosis of Tetralogy of Fallot?
Depends on severity- poor without treatment. 90% make it to adulthood with corrective surgery
What is Ebstein’s anomaly?
Congenital heart condition where the tricuspid valve is set lower in the right side of the heart, causing a bigger right atrium and smaller right ventricle
What does Ebstein’s anomaly do to the flow in the heart?
Lead to poor flow from the right atrium to the right ventricle, causing poor flow to the pulmonary vessels
What is Ebstein’s anomaly often associated with?
A right to left shunt across the atria via an atrial septal defect, and therefore cyanosis
What syndrome is Ebstein’s anomaly associated with?
Wolff-Parkinson-White syndrome
What is the presentation of Ebstein’s anomaly?
Heart failure Gallop rhythm Cyanosis SOB Tachypnoea Poor feeding Collapse/ cardiac arrest
What is heard on auscultation of Ebstein’s anomaly?
Gallop rhythm caused by addition of third and fourth heart souds
How is Ebstein’s anomaly diagnosed?
Echo
How is Ebstein’s anomaly managed?
Treating arrhytmias and heart failure
Prophylactic antibiotics for IE
Surgical correction of underlying defect
What is transposition of the great arteries?
Condition where the attachments of the aorta and pulmonary trunk to the heart are swapped
Explain what transposition of the great arteries causes?
Two separate circulations: The right ventricle pumps blood into the aorta and systemic circulation, and the left ventricle pumps blood into the pulmonary vessels and pulmonary circulation
What is transposition of the great arteries associated with?
Ventricular septal defect
Coarctation of the aorta
Pulmonary stenosis
How will the baby present at birth with transposition of the great arteries?
Cyanosed
What does immediate survival of a neonate with transposition of the great arteries depend on?
Shunts between systemic and pulmonary circulation (e.g. patent ductus arteriosus, atrial septal defect or ventricular septal defect)
When is transposition of the great arteries usually diagnosed?
During pregnancy with antenatal USS
What happens if a fetus is diagnosed with transposition of the great arteries?
Close monitoring during pregnancy and admission to a hospital capable of managing condition after birth
If the condition is not detected during pregnancy, how will transposition of the great arteries present?
With cyanosis at or soon after birth
How is transposition of the great arteries managed?
Prostaglandin infusion to maintain ductus arteriosus
Balloon septostomy
Open heart surgery
What is a balloon septostomy?
Inserting a catheter into the foramen ovale via the umbilius, and inflating the balloon to create a large atrial septal defect, allowing blood from the lungs to flow to the right side of the heart.
How is open heart surgery performed to treat transposition of the great arteries?
Cardiopulmonary bypass machine used to perform an arterial switch procedure within a few days of birth
