Paediatrics 1 Flashcards
What are the 3 fetal shunts
Ductus Venosus
Foramen Ovale
Ductus arteriosus
Ductus venosus function
Connects umbilical vein to IVC to bypass liver
Foramen ovale function
Connects RA to LA allowing blood to bypass RV and pulmonary circulation
Ductus arteriosus
Connects PA with aorta to allow blood to bypass pulmonary circulation
How is the foramen ovale closed
First breaths of baby expands the alveoli, decreasing pulmonary vascular resistance (PVR)
Decrease in PVR causes a fall in RA pressure. Hence LA pressure is greater than RA, squashing atrial septum to cause functional closure.
What keeps the ductus arteriosus open
Prostaglandins. Increased blood oxygenation causes a drop in circulating prostaglandins
What is the ligamentum arteriosum a remnant of?
Ductus arteriosus
How does ductus venosus become the ligamentum venosum
Ductus venosus stops functioning after birth due to umbilical cord clamping. No blood flows through umbilical vein and ductus venosus structurally closes.
Innocent murmurs/flow murmurs
Fast blood flow through various areas of heart during systole
Features of innocent murmurs (5)
Short Short Systolic Symptomless Situation dependent
When to refer innocent murmur to cardiologist? (4)
Murmur louder than 2/3
Diastolic murmurs
Louder on standing
Symptoms - Failure to thrive, feeding difficulty, cyanosis, SOB
Innocent murmurs investigations
ECG
CXR
Echo
Pan-systolic murmurs DDx
Mitral regurgitation
Tricuspid regurgitation
VSD
Ejection systolic murmurs
Aortic stenosis
Pulmonary stenosis
Hypertrophic obstructive cardiomyopathy
Splitting of second heart sound pathophysiology
During inspiration, the chest wall and diaphragm pull the lungs open. This pulls the heart open. This causes Right side of heart to fill faster as it pulls blood in from venous system.
Increase in volume of the RV causes delay for RV emptying during systole so delay in pulmonary valve closure.
When the pulmonary valve closes slightly later than aortic, this causes second heart sound split
ASD sound
mid-diastolic, crescendo-decrescendo murmur loudest at upper left sternal border WITH
fixed split second heart sound
PDA sound
Normal first heart sound with a continuous crescendo-decrescendo machinery murmur that may continue during the second heart sound, making the second heart sound difficult to hear
Tetralogy of Fallot sound
Ejection systolic murmur loudest at pulmonary area (arises from pulmonary stenosis)
Cyanotic heart disease causes (4)
Heart defects that can cause right to left shunt
VSD
ASD
PDA
Transposition of great arteries
Which heart defect will always have cyanosis
Transposition of the great arteries. As right side of the heart pumps blood directly into the aorta and systemic circulation.
PDA?
When the ductus arteriosus fails to close
Key risk factor of PDA
Prematurity
Reasons for PDA?
Unclear but may be genetic/ due to maternal infections such as rubella.
PDA pathophysiology
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 RS heart strain as right ventricle struggles to contract against increased resistance.
This leads to RV hypertrophy and the increased blood flowing through the pulmonary vessels returning to LS of heart leads to LV hypertrophy.
PDA presentation (4)
SOB
Difficulty feeding
Poor weight gain
Lower RTI
PDA murmur
A small patent ductus arteriosus may not have any abnormal heart sounds. More significant PDAs cause a normal first heart sound with a continuous crescendo-decrescendo “machinery” murmur that may continue during the second heart sound, making the second heart sound difficult to hear.
PDA investigation
Diagnosis confirmed by echocardiogram. Effects of PDA e.g. hypertrophy also demonstrated.
The use of doppler flow studies during the echo can assess the size and characteristics of the left to right shunt.
PDA management
Patients monitored until 1 year of age using echocardiograms.
If not closed, trans-catheter/surgical closure performed.
ASD?
Defect in septum between the two atria.
ASD pathophysiology
During the development of the fetus the left and right atria are connected. Two walls grow downwards from the top of the heart, then fuse together with the endocardial cushion in the middle of the heart to separate the atria. These two walls are called the septum primum and septum secondum.
Defects this these two walls lead to atrial septal defects, a hole connecting the left and right atria. There is a small hole in the septum secondum called the foramen ovale. The foramen ovale normally closes at birth.
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, however the increased flow to the right side of the heart leads to right sided overload and right heart strain. This right sided overload can lead to right heart failure and pulmonary hypertension.
Eventually pulmonary hypertension can lead to 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.
Types of ASD (3)
Ostium secondum
Patent Foramen Ovale
Ostium Primum
Complications of ASD (4)
Stroke
AF/ atrial flutter
Pulmonary HTN and RS HF
Eisenmenger syndrome
ASD presentation
SOB
Difficulty feeding
Poor weight gain
Lower RTI
ASD management
Referral to paediatric cardiologist
Correction with transvenous catheter closure or open heart surgery
ASD murmur.
mid-systolic, crescendo-decrescendo murmur loudest at the upper left sternal border with a fixed split second heart sound. Splitting of the second heart sound is where you hear the closure of the aortic and pulmonary valves at slightly different times. This can be normal with inspiration, however a “fixed split” second heart sound means the split does not change with inspiration or expiration. This occurs in an atrial septal defect because blood is flowing from the left atrium into the right atrium across the atrial septal defect, increasing the volume of blood that the right ventricle has to empty before the pulmonary valve can close.
VSD associations?
Down’s syndrome
Turner’s syndrome
VSD pathophysiology?
Due to the increased pressure in the left ventricle compared to the right, blood typically flows from left the right through the hole. Blood is still flowing around the lungs before entering the rest of the body, therefore they remain acyanotic (not cyanotic) because their blood is properly oxygenated. A left to right shunt leads to right sided overload, right heart failure and increased flow into the pulmonary vessels.
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
VSD presentation
Often initially symptomless. Otherwise,
Poor feeding
Dyspnoea
Tachypnoea
Failure to thrive
Examination findings VSD
Pan-systolic murmur more prominently heard at the left lower sternal border in the 3rd & 4th intercostal spaces
There may be a systolic thrill on palpation.
Causes of pan-systolic murmurs
VSD
MR
TR
VSD treatment
Transvenous catheter closure via femoral vein/ open heart surgery
Complications of VSD and prevention
Increased risk of infective endocarditis.
Antibiotic prophylaxis should be considered during surgical procedures.
Eisenmenger syndrome?
Condition which occurs when blood flows from the right side of the heart to the left across a structural heart lesion, bypassing the lungs.
Lesions that can cause Eisenmenger syndrome
ASD
VSD
PDA
Eisenmenger syndrome 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.
Eisenmenger syndrome examination findings (4) (4)
RV heave
Loud P2: loud second heart sound due to forceful shutting of pulmonary valve
Raised JVP
Peripheral oedema
Findings related to right left shunt and chronic hypoxia Cyanosis Clubbing Dyspnoea Plethoric complexion
Eisenmenger syndrome management
Heart-lung transplant
Coarctation of the aorta
Congenital condition where there is narrowing of the aortic arch, usually around the ductus arteriosus
Coarctation of aorta association
Turners syndrome
Pressure distribution for coarctation of aorta
Reduces pressure of blood flowing to arteries distal to narrowing and increase in areas proximal to narrowing, such as first three branches of the aorta.
Coarctation of aorta presentation (7)
Weak femoral pulses in neonates
Systolic murmur may be heard below the left clavicle and below the left scapula
tachypnoea
Poor feeding
Grey and floppy baby
Left ventricular heave
Underdeveloped left arm where there is reduced flow to the left subclavian artery
Underdevelopment of legs
Coarctation of aorta management (2)
Prostaglandin E is used to keep ductus arteriosus open while waiting for surgery
Surgery is then performed to correct the coarctation and to ligate the ductus arteriosus.
What are the leaflets of the aortic valve called
aortic sinuses of valsalva
How many aortic valve leaflets would aortic stenosis patients have?
May have 1/2/3/4 leaflets
Aortic stenosis presentation (3)
SOB
Syncope on exertion
Angina
Aortic stenosis signs
The key examination finding is an ejection systolic murmur heard loudest at the aortic area, which is the second intercostal space, right sternal border. It has a crescendo-decrescendo character and radiates to the carotids.
Other signs that may be present on examination are:
Ejection click just before the murmur
Palpable thrill during systole
Slow rising pulse and narrow pulse pressure