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Paediatrics (Y4) > 4- Paediatric Cardiology (Acynotic defects) > Flashcards

4- Paediatric Cardiology (Acynotic defects) Flashcards

1
Q

Pressures and oxygenation of mature circulation

A

1. Right ventricle pumps deoxygenated bloods to lungs
- pO2 is 67%
- Venous pressure in atrium 4mmHg
- Pressure 25/3 mmHg in the ventricle
- Blood moves from the atria to ventricle due to ventricle diastole and atria systole (contraction)

2. Pulmonary circulation has low resistance
- pressure is 25/10mmg in pulmonary trunk

3. Left ventricle pumps oxygenated blood at systemic blood pressure to aorta
- pO2 is 99-100%
- left atria- slightly higher pressure than in right atria- 8-10mmHg
- Left ventricle – 120/10 mmHg
(120 is the pressure needed to pump around the whole body )
- aorta pressure- 120/80mmHg

4. Each ventricle is morphologically adapted for its task
- Left ventricle has much more muscle

In summary
Right heart
- Low resistance
- Low pressure
- Blue blood

Left heart
- High resistance
- High pressure
- Red blood

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2
Q

mature vs fetal circulation

A

In mature circulation:
- Deoxygenated blood collected from the body
- Pumped to the lungs for reoxygenation and removal of CO2
- Reoxygenated blood returned from the lungs to the heart
- Pumped around the body

In the foetus:
- Lungs don’t work
- Oxygenation and removal of CO2 occur at the placenta
- Since the fetal lungs are not fully developed it does not make sense for fetal blood to pass through pulmonary circulation
- So Shunts are required to maintain foetal life
- Shunts must be reversible at birth
(the min the baby is born (as soon as the first breath is taken) the shunts must close)

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3
Q

Ducts/shunts

A

- Ductus venosus by-pass the liver (highly metabolic)- connects umbilical vein to IVC
- Foramen ovale- by-pass the right ventrical and lungs- connects right atrium and left atrium
- Ductus arteriosus- by-pass the lungs- shunts connect pulmonary artery and aorta

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4
Q

Foetal circulation

A
  1. Oxygenated bloods is carried from the placenta into the foetal circulation via the umbilical vein
  2. Oxygenated blood enter the inferior vena cava and mixes with deoxygenated blood- bypasses the developing liver via the ductus venosus
    - Liver is very metabolically active- so bypassing it means that oxygenated blood can maintain its oxygen saturation for when it reaches the heart to be pumped around the body
  3. The blood enter the right atrium and passes into the left atrium via the foramen ovale (when its closes become fossa ovalis) thereby bypassing the pulmonary circulation-> not fully developed yet so wouldn’t tolerate the pressure
    - The blood can shunt from right to left side of the heart because the pressure in the right side of the heart is higher than the left in the foetus
    - The baby is not breathing and instead the foetus’ blood is being oxygenated by the mothers blood
    - Therefore blood doesn’t have to go to the alveoli for oxygenation- so pulmonary circulation can be bypassed
  4. The blood is pumped from the left ventricle into the aorta
  5. Blood that doesn’t pass through the foramen ovale, and instead is pumped into the pulmonary trunk from the right ventricle, enter systemic circulation at the arch of the aorta via the ductus arteriosus
    - This system exists so that the right ventricle still has some blood to pump against. In the developing heart, the rule of ‘use it or lose it’ applies, so if the right ventricle has no blood passing though it, it will be underdeveloped in the mature heart. This is relevant in congenital heart defects such as tricuspid atresia.
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5
Q

neonatal circulation straight after birth

A

After birth…
1. Baby takes first breath and pO2 increases, this causes the circulating prostaglandins to drop (prostaglandins keeps ductus arteriosus open). Therefore the Ductus arteriosus contracts -> becomes the ligamentum arteriosum
2. More blood now flows through pulmonary circulation as blood in the pulmonary trunk cannot leave via the ductus arteriosus anymore
3. This causes increased venous return to the left atrium, leading to an increase in left atrial pressure. When the pressure in the LA exceeds the RA the foramen ovale closes -> becomes fossa ovalis
4. When the umbilical cord is cut, there is no longer blood flowing through the umbicilical vein, causing the ductus venosus to collapse -> becomes ligamentum venosum

Therefore
- Ductus arteriosus -> ligamentum arteriosum
- Foramen ovale -> fossa ovalis
- Ductus venosus -> ligamentum venosum

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6
Q

Classification of congenital HD

A

1) Acyanotic
2) Cyanotic

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7
Q

acyanotic

A
  • Well perfused= pink babies
  • Left to right shunt
  • Oxygenated blood mixing with deoxygenated blood

Examples

  • Atrial Septal Defects
  • Ventricular Septal Defects
  • Patent Ductus Arteriosus

Obstructive lesions:

  • Aortic stenosis (hypoplasia)
  • Pulmonary stenosis (valve, outflow branch)
  • Coarctation of the aorta (narrowing) and mitral stenosis

Pathophysiology

  • Shunts cause too much blood to the lungs–> pulmonary hypertension
  • Increased pulmonary pressure causes damage to lungs
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8
Q

cyanotic

A
  • Poorly perfused= blue
  • Circulating systemic oxygen levels are lower
  • Right to left shunts

Examples

  • Tetralogy of fallow (VSD/pulm stenosis)
  • Transposition of the great arteries
  • Tricuspid atresia
  • Total anomalous pulmonary venous drainage
  • Univentricular heart
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9
Q

Respiratory cyanosis

A
  • Asphyxiation
  • Pneumonia
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10
Q

Aetiology of congenital HD

A

Genetic:
- Downs, Turners, Marfan’s
- Polygenic

Environmental
- Teratogenicity from drugs, alcohol etc

Maternal infections
- Rubella, toxoplasmosis

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11
Q

associations with CHD

A

Associations
- Extracardiac defects
o Brain
o Bone length
o Kidney
o Palate
- Chromosomal anomalies
o T21 – 33-50%
o Alagille syndrome
o DiGeorge syndrome

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12
Q

Antenatal diagnosis of CHD

A
  • Fetal medicine scan
  • Offer amniocentesis or NIPT (private)
  • Empower and prepare parents and family
  • Delivery plans
  • Neonatal care
  • Allow bonding with baby
  • Specialist fetal cardiac nurses
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13
Q

Central vs peripheral cyanosis

A

Central cyanosis occurs when the partial pressure of oxygen (pO2) in the systemic circulation is low.
 Babies have a blue discolouration to their face, mouth and tongue.

Peripheral cyanosis is blue discolouration of the peripheries due to reduced perfusion, e.g. in cold weather, arteries to the fingers and toes constrict

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14
Q

Acynotic defects

A

Presentation
- Won’t immediately present with central cyanosis -> blood in the systemic circulation is fully saturated with oxygen so the pO2 is maintained

Examples
Left to right shunts
- Atrial septal defects (ASD)
- Ventricular septal defect (VSD)
- Patient ductus arteriosus (PDA)

Obstructive lesions
- Aortic stenosis (hypoplasia)
- Pulmonary stenosis (valve, outflow, branch)
- Mitral stenosis

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15
Q

atrial septal defect background

A
  • Hole between the left and right atria
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16
Q

ASD pathophysiology

A
  • Caused by underdevelopment of the septum primum (ostium primum) or secundum (ostium secundum), resulting in a hole in the atrial septum
    o Allows blood in the left atrium to flow into the right atrium
  • Increased volume in the right atrium leads to a higher volume of blood being pumped around the pulmonary circulation
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17
Q

ASD: Why is it a problem?

A
  • If left untreated, this will cause damage to the vasculature and fibrosis of the arteries in the lungs
  • Making arteries less distensible which increases resistance to blood flow and results in pulmonary hypertension:
    o Meaning right side of the heart must work against the increased AFTERLOAD
    o Can cause right heart enlargement (hypertrophy)-> leading to right sided heart failure
    o Can also cause pulmonary oedema as blood under high pressure forces fluid out of the capillaries into the lungs
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18
Q

presentation of ASD

A
  • Often picked up during antenatal scans or newborn examinations
  • Often asymptomatic in childhood and can present in adulthood with heart failure or stroke

Murmur
- Mid-systolic, crescendo-decrescendo murmurs
- Loudest at the upper left sternal border
- Fixed split second heart sound
–> Can be normal with inspiration, however a fixed split second heart sound means the split does not change with inspiration and expiration
–> Doesn’t vary with respiration

Typical symptoms
- SoB
-Difficulty feeding
-Poor weight gain
- Lower respiratory tract infections

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19
Q

Investigations for ASD

A
  • ECG – RBBB subtle
  • Echocardiogram – right side dilated
  • CXR normal
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20
Q

Management of ASD

A
  • If small and asymptomatic- watch and wait
  • Can be corrected using transvenous catheter closure (via the femoral vein) or open heart surgery
  • Anticoagulants (aspirin, warfarin, NOACS) used to reduce risk of strokes
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21
Q

Complications of ASD

A
  • Stroke in the context of venous thromboembolism (see below)
    o Causes stroke in patients with DVT-
    o DVT becomes a PE and due to septal defect, the clot can travel from the right atrium to the left up the aorta and into the brain -> large stroke
  • Atrial fibrillation or atrial flutter
  • Pulmonary hypertension and right sided heart failure
  • Eisenmenger syndrome
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22
Q

patent foramen ovale (PFO) vs ASD

A

A patent foramen ovale (PFO) is not classed as an ASD. PFO is caused by the failure of the foramen ovale to shut after birth. It is not an ASD because it is a unidirectional shunt (right atrium to left atrium) and there is no defect in the septum of the atria. In adults it generally doesn’t cause symptoms. This is because the pressure in the left ventricle is higher than that in the right, so the shunt does not allow blood to move down this gradient.

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23
Q

Ventricular septal defect (VSD) background

A
  • Congenital hole in septum between ventricles
  • Can vary in size from tiny to the entire septum
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24
Q

RF for VSD

A

Risk factors
- Down syndrome
- Turners syndrome

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25
Q

Pathophysiology of VSD

A
  • During development of the interventricular septum, the membranous portion of the septum fails to develop properly
    o Primary interventricular foramen remains open
  • Blood in the left ventricle will flow into the right ventricle
  • The pressure difference between the ventricles is greater than that between the atria, so more blood movement in VSD than ASD
26
Q

Why is VSD a problem?

A
  • By the same mechanism as ASD, VSD if left untreated will cause pulmonary hypertension, right sided hypertrophy -> heart failure
  • Can also cause Eisenmenger syndrome
27
Q

presentation of VSD

A

Murmurs
- Pan-systolic murmurs
- Heard most prominently on the left lower sternal border in the 3rd and 4th intercostal space
- Systolic thrill on palpation

Initially symptomless – start at around3-5 weeks
- Can present ass late as adulthood
- May be picked up on antenatal scans or new born check

Typical symptoms
* Poor feeding
* Dyspnoea
* Tachypnoea
* Failure to thrive

28
Q

Investigations VSD

A
  • CXR
    o Increased size heart
  • Echo
  • ECG normal
29
Q

Management of VSD

A
  • Small VSD with no symptoms or evidence of pulmonary hypertension or heart failure
    o Often close spontaneously
  • Can be corrected surgically using transvenous catheter closure via femoral vein or open heart surgery
  • Increased risk of infective endocarditis -> prophylactic endocarditis considered during surgical procedure to reduce risk of infection
30
Q

Patent ductus arteriosus (PDA)
Background

A
  • Ductus arteriosus usually stops functioning within 1-3 days of birth and completely within 2-3 weeks
  • If it fails to close -> PDA
31
Q

causes / RF for PDA

A

Causes
- Unclear
- Rubella

Risk factors
- Prematurity

32
Q

Pathophysiology of PDA

A
  • Ductus arteriosus connecting the right pulmonary artery to the arch of the aorta normally shunts after the baby takes its first breath, however in PDA it remains open
  • Left to right shunt
  • This patent connection allows blood under high pressure in the aorta to flow into the pulmonary artery
33
Q

PDA Why is it a problem?

A
  • This result in a higher volume of blood in the pulmonary artery, leading to a high AFTERLOAD for the right ventricle, which can eventually causes right-sided heart failure
  • This is acyanotic heart defect because the blood reaching the systemic circulation is fully saturated with oxygen from, the lungs
34
Q

presentation of PDA

A

Murmur

  • May not cause any abnormal heart sounds
  • Continuous crescendo-decrescendo “machinery” murmur that may continue during second heart sound making it hard to hear

General presentation

  • Asymptomatic
  • May remain asymptomatic throughout childhood and present in adulthood with signs of heart failure

Other symptoms:

  • SoB
  • Difficulity feeding
  • Poor weight gain
  • LRTI
35
Q

Investigations for PDA

A
  • Echocardiogram- can demonstrate hypertrophy of right ventricle
  • Use of doppler flow studies during the echo can assess the size and character of left to right shunt
36
Q

Management of PDA

A
  • Monitored until 1 year using echo
  • After 1 year highly likely PDA will close spontaneously and trans-catheter and surgical closure can be performed
  • Symptomatic patients will be treated earlier
37
Q

Atrioventricular septal defect background

A
  • Caused by failure of the endocardial cushions to develop properly
  • Results in a hole in the middle of the heart with one common atrioventricular valve, instead of a mitral and pulmonary valve
  • Common in Down’s syndrome
38
Q

atrioventricular septal defect presentation

A

Murmur
(an abnormal “whooshing” sound caused by blood flowing through the abnormal hole). However, not all heart murmurs are present at birth. Babies with a complete AVSD usually do show signs of problems within the first few weeks after birth. When symptoms do occur, they may include
- mid-diastolic rumbling murmur, audible along the lower left sternal border.

General symptoms
* Breathing problems
* Pounding heart
* Weak pulse
* Ashen or bluish skin color
* Poor feeding, slow weight gain
* Tiring easily
* Swelling of the legs or belly

39
Q

investigations for atrioventricular septal defect

A
  • echocardiogram
  • CXR
40
Q

management of atrioventricular defect

A

All AVSDs, both partial and complete types, usually require surgery. During surgery, any holes in the chambers are closed using patches. If the mitral valve does not close completely, it is repaired or replaced. For a complete AVSD, the common valve is separated into two distinct valves – one on the right side and one on the left side.

The age at which surgery is done depends on the child’s health and the specific structure of the AVSD. If possible, surgery should be done before there is permanent damage to the lungs from too much blood being pumped to the lungs. Medication may be used to treat congestive heart failure, but it is only a short term measure until the infant is strong enough for surgery.

Infants who have surgical repairs for AVSD are not cured; they might have lifelong complications. The most common of these complications is a leaky mitral valve. This is when the mitral valve does not close all the way so that it allows blood to flow backwards through the valve.

41
Q

Obstructive congenital heart defects

A

e.g. Aortic/pulmonary stenosis, coarctation of the aorta, mitral stenosis

42
Q

pulmonary stenosis

A

Narrowed pulmonary valve

43
Q

Pathophysiology of pulmonary stenosis

A
  • Pulmonary valve usually consists of three leaflets that open and close to let blood out and prevent blood from returning to the heart.
  • These leaflets can develop abnormally, becoming thickened or fused.
  • This results in a narrow opening between the right ventricle and the pulmonary artery.
  • This is called congenital pulmonary valve stenosis.
44
Q

Associations of pulmonary valve stenosis

A
  • Tetralogy of fallot
  • William syndrome
  • Noonan syndrome
  • Congenital rubella
45
Q

pulmonary stenosis presentation

A

Murmur

  • Ejection systolic murmur heard loudest at the pulmonary area
  • Palpable thrill in pulmonary area
  • Right ventricular heave due to right ventricular hypertrophy
  • Raised JVP with giant a waves

Often asymptomatic and incidental finding

Typical symptoms

  • Fatigue on exertion
  • SoB
  • Dizziness
  • Fainting
46
Q

investigations for pulmonary stenosis

A

echocardiogram

47
Q

management of pulmonary stenosis

A
  • Mild- watch and wait

If symptomatic

  • Balloon valvuloplasty via venous catheter
  • If not appropriate open heart surgery
48
Q

Aortic stenosis background

A
  • Patients are born with narrow aortic valves which restrict blood flow from the left ventricle to the aorta
  • Severity of stenosis will determine symptoms
49
Q

Pathophysiology of aortic stenosis

A
  • Aortic valve usually made up of three leaflets (semilunar valves)- aortic sinuses of Valsalva, which allow blood to flow from the left ventricle to the aorta- they prevent blood from flowing back into the left ventricle
  • Patients with aortic stenosis may have one, two or three or four leaflets
  • Results in left/right ventricular hypertrophy as the heart is having to generate more force to push blood through the stenosed valve
  • Hypertrophy can lead to heart failure
50
Q

presentation of aortic stenosis

A

Murmur

  • Ejection systolic murmur- aortic area (second intercostal space, right sternal border)
  • Crescendo-decrescendo character and radiates to the carotids
  • Palpable thrill
  • Slow rising pulse and narrow pulse pressure
    Typical symptoms
  • Asymptomatic
  • Fatigue
  • SoB
  • Dizziness
  • Fainting
  • Worse on exertion
  • Severe aortic stenosis will present with HF within months
51
Q

Investigations of aortic stenosis

A
  • Echocardiogram- gold standard investigation
  • Progressive condition
    o Echos
    o ECGs
    o Exercise testing to monitor progress of condition
52
Q

management of aortic stenosis

A
  • Echocardiogram- gold standard investigation
  • Progressive condition
    o Echos
    o ECGs
    o Exercise testing to monitor progress of condition
53
Q

management of aortic stenosis

A
  • Percutaneous balloon aortic valvoplasty
  • Surgical aortic valvotomy
  • Valve replacement
54
Q

Complications of aortic stenosis

A
  • Left ventricular outflow tract obstruction
  • Heart failure
  • Ventricular arrhythmia
  • Bacterial endocarditis
  • Sudden death, often on exertion
55
Q

Coarctation of the aorta background

A
  • Congenital narrowing of part of the aorta- commonly around the ductus arteriosus area
  • Severity can vary from mild to severe
56
Q

risk factor for coarctation of the aorta

A
  • Male more common
  • Bicuspid valve
  • Turners syndrome
57
Q

pathophysiology of coarctation of the aorta

A
  • Male more common
  • Bicuspid valve
  • Turners syndrome
58
Q

pathophysiology of coarctation of the aorta

A
  • Upstream of the coarctation (towards the heart), blood pressure is high because it struggles to flow past the coarctation
    o Increases risk of aneurysms of the aortic arch, and aortic root dilation which can lead to aortic valve regurgitation
  • Downstream of the coarctation (towards the body), patients will have weak pulses and claudication (cramping in the legs due to reduced perfusion)
  • If narrowing is after the 3 branches of the arch of the aorta, there will be a delay between feeling the radial and femoral pulses (radio-femoral delay)
  • If narrowing is between the brachiocephalic trunk and the left subclavian, then there will be a delay between feeling the radial pulses in both wrists- radial-radial delay
59
Q

presentation of coarctation of the aorta

A
  • Murmur
    Systolic murmur heard below the left clavicle and below the scapular
    Left ventricular heave due to left ventricular hypertrophy

Presentation
- Neonatal collapse
- Often the only indication is weak/absent femoral pulses
- Claudication in legs due to reduced perfusion
- Radio-femoral delay
- Strong radial pulses

Typically symptoms
* Tachpnoea
* Poor feeding
* Grey and floppy baby
* Other- underdevelopment of left arm or of the legs

60
Q

Management of coarctation of the aorta

A
  • Mild cases- patient can live symptoms free until adulthood without requiring surgical input
  • Severe cases- will require emergency surgery shortly after birth
61
Q

Critical coarctation

A
  • Risk of HF and death shortly after birth
  • Management: prostaglandin E is used -> used to keep ductus arteriosus open while waiting for surgery
  • allows some blood flow through ductus arteriosus into the systemic circulation distal to the coarctation
  • Surgery is then performed to correct the coarctation to ligate ductus arteriosus
62
Q

Eisenmenger syndrome

A

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

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.

Pathophysiology
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. Remember, the left ventricle has to pump blood through the entire body, whereas the right ventricle simply has to fill the lungs. A left to right shunt 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.

Paediatrics (Y4) (42 decks)

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