Paediatrics Cardiology Flashcards
What are the 3 fetal shunts?
Ductus venosus: bypass liver (umbilical vein to IVC)
Foramen ovale: bypass right ventricle and pulmonary circulation (connects right and left atriums)
Ductus arteriosus: bypass pulmonary circulation (connects pulmonary artery with aorta)
What happens when a baby takes its first breath at birth?
First breaths the baby takes expands the alveoli which decreases the pulmonary vascular resistance causing a fall in pressure in the right atrium.
At this point the left atrial pressure is greater than the right atrial pressure - squashed the atrial septum causing foramen ovale to close
What happens to the foramen ovale?
Gets sealed shut structurally after a few weeks becoming the fossa ovalis
What happens to the ductus arteriosus?
Prostaglandins are required to keep the ductus arteriosus open and an increase in blood oxygenation causes a drop in circulating prostaglandins causing closure of the ductus arteriosus which becomes the ligamentum arteriosum
What happens to the ductus venosus?
Immediately after birth the ductus venosus stops functioning because the umbilical cord is clamped and there is no flow in the umbilical veins (ductus venosus structurally closes a few days later and becomes the ligamentum venosum)
What are innocent murmurs also known as?
Flow murmurs (caused by blood flow through various areas of the heart during systole)
What are the features of innocent murmurs?
Soft
Short
Systolic
Symptomless
Situation dependent (if the murmur is quieter with standing or only appears when the child is unwell or feverish)
When should a murmur be referred to a paediatric cardiologist?
- Murmur louder than 2/6
- Diastolic murmur
- Louder on standing
- Other symptoms such as failure to thrive, feeding difficulty, cyanosis or SoB
What are the key investigations for a suspious murmur in a child?
ECG
Chest X-Ray
Echocardiography
What are the differentials for a pan systolic murmur? How are they differentiated?
Mitral regurgitation - heard at mitral area (5th intercostal space, mid-clavicular line)
Tricuspid regurgitation - heard at tricuspid area (5th intercostal space, left sternal border)
Ventricular septal defect - heard at left lower sternal border
What are the differentials for an ejection systolic murmur? How are they differentiated?
Aortic stenosis - heard at the aortic area (2nd intercostal space, right sternal border)
Pulmonary stenosis - heard at the pulmonary area (2nd intercostal space, left sternal border)
Hypertrophic obstructive cardiomyopathy heard at the 4th intercostal space on the left sternal border
What causes splitting of the second heart sound?
Inspiration = heart is pulled open (negative intra-thoracic pressure)
Causes the right side of the heart to fill faster as it pulls in blood from the venous system
Increased volume in the right ventricle causes it to take longer for the right ventricle to empty during systole causing a delay in the pulmonary valve closing (when this closes slightly later than the aortic valve this causes the heart sound to be split)
What type of murmur does an atrial septal defect cause?
Mid-systolic, crescendo-decrescendo murmur lousest at the upper left sternal border with a fixed split second heart sound
What is a fixed split second heart sound?
Split doesnt change with inspiration and expiration
Why does a fixed split second heart sound occur in an atrial septal defect?
Because blood is flowing from the left atrium across the atrial septal defect increasing the volume of bloos that the right ventricle has to empty before the pulmonary valve can close (doesn’t vary with respiration)
How does a patent ductus arteriosus sound?
Continuous crescendo-decrescendo “machinery” murmur that may continue during the second heart sound making it difficult to hear
How does the murmur in tetralogy of fallot sound?
Arises from pulmonary stenosis giving an ejection systolic murmur which is loudest at the pulmonary area (second intercostal space, left sternal border)
When does cyanotic heart disease occur?
On a right to left shunt
What can cause cyanotic heart disease?
Ventricular septal defect (VSD)
Atrial septal defect (ASD)
Patent ductus arteriosus (PDA)
Transposition of the great arteries
What is Eisenmenger syndrome?
If the pulmonary pressure increased beyond the systemic pressure then blood with start to flow from right-to-left across the defect causing cyanosis
Why does a patent ductus arteriosus occur?
Unclear, may be genetic or related to maternal infections e.g. rubella (prematurity is a key factor)
How may a small PDA present?
Asymptomatic throughout childhood then present in adulthood with signs of heart failure
What is the result of a patent ductus arteriosus?
Pressure in the aorta is higher than in the pulmonary vessels- blood flows from the aorta to the pulmonary artery (creating a left to right shunt)
Increases pressure in the pulmonary vessels causing pulmonary hypertension leading to right sided heart strain causing right ventricular hypertrophy.
Increase in blood flowing through the pulmonary vessels and returning to the left side of the hear leads to left ventricular hypertrophy
How does a patent ductus arteriosus present?
- Shortness of breath
- Difficulty feeding
- Poor weight gain
- Lower respiratory tract infections
How is a patent ductus arteriosus diagnosed?
Echocardiogram (doppler flow studies during the echo can assess the size and characteristics of the shunt - echo can also assess hypertrophy of the heart)
How are patients with a patent ductus arteriosus managed?
Monitored until 1 year of age using echocardiograms- after 1 year of age its unlikely that the PDA will close spontaneously and atranscatheterorsurgical closure can be performed
Symptomatic patients or those with evidence of heart failure as a reault of PDA are treated earlier
How do the atria develop?
During development left and right atria are connected - two walls grow downwards from the top of the heart and then fuse together with the endocardial cushion in the miss of the heart to separate the atria
2 walls = septum primum and septum secundum
Which atrial wall is the foramen ovale in?
Septum secondum
What can cause atrial septal defects?
Ostium secondum where the septum secondum fails to close full, leaving a hole in the wall
Patent foramen ovale where the foramen ovale fails to close (although this isnt strictly classed as an ASD)
Ostium primum where the septum primum fails to fully close, leaving a hole in the wall - leading to atrioventricular valve defects making it an atrioventricular septal defect
What is a complication of an artial septal defect?
Stroke (in the context of a VTE)
Atrial fibrillation or atrial flutter
Pulmonary hypertension and right sided heart failure
Eisenmenger syndrome
What kind of murmur does an atrial septal defect cause?
Mid-systolic, crescendo-decrescendo murmus loudest at the upper left sternal border with a fixed split second heart sound
How may an ASD present in adulthood?
Dyspnoea
Heart failure
Stroke
What are the symptoms in childhood for ASD?
- SoB
- Difficulty feeding
- Poor weight gain
- Lower respiratory tract infections
What is the interesting link with patent foramen ovale?
Have been linked to migraine with aura
What is the management of ASD?
- Referral to paediatric cardiologist
- Corrected surgically using a transvenous catheter closure (via femoral vein) or via open heart surgery
- Anticoagulants (such as aspirin, warfarin and NOACs) used to reduce the risk of clots and stokes in adults
What is a ventricular septal defect?
Congenital hole in the septum between the two ventricles (vary in size from tiny to the entire septum forming one large ventricle)
What are ventricular septal defects associated with?
Down’s syndrome
Turner’s syndrome
What does a ventricula septal defect lead to?
Right sided overload, right heart failure and increased flow into the pulmonary vessels