Cardiology Flashcards
What is the purpose of the fetal shunts/why do fetus’ require fetal shunts?
Lungs are not fully developed or functional (fetus is not breathing) therefore there is no point in blood passing through the pulmonary circulation and secondly large volumes of blood passing through lungs could cause damage
For each of the 3 fetal shunts, state:
- The name of the shunt
- Where it shunts blood from and to
- What the shunt is trying to bypass
- Ductus venosus: umbilical vein to IVC to allowing blood to bypass liver
- Foramen ovale: right atrium to left atrium allowing blood to bypass right ventricle & the pulmonary circulation
- Ductus arteriosus: pulmonary artery to the aorta allowing blood to bypass the pulmonary circulation
Describe what happens to the fetal shunts at birth when baby takes it’s first breath
Foramen ovale
- When baby takes it’s first breath it expands the alveoli
- Causing decrease in pulmonary vascular resistance
- Causing fall in pressure in RA
- LA pressure > RA pressure
- Septum primum forced against septum secundum causing functional closure of foramen ovale (gets sealed shut few weeks later and becomes fossa ovalis)
Ductus Arteriosus
- Prostaglandins are required to keep it open
- Increased blood oxygenation causes decrease in circulating prostaglandins
- Therefore ductus arteriosus closes within 1-3 days after birth (in full term babies) and becomes ligamentum arteriosum
Ductus venosus
- Umbilical cord is clamped immediately after birth therefore there is no flow through umbilical veins hence ductus venosus stops functioning
- Closes a few days later to become ligamentum venosum
State some potential risk factors for congenital heart disease
While some things are known to increase the risk of congenital heart disease, no obvious cause is identified in most cases:
- Rubella infection in first 8-10 weeks pregnancy
- Influenza infection in first trimester
- Alcohol use during pregnancy (may lead to fetal alcohol syndrome which is associated with congenital heart disease)
- If mother has T1DM or T2DM (not gestational diabetes)
- Genetic conditions e.g. Down’s syndrome, Noonan syndrome, Turner syndrome
State the 8 cyanotic congenital heart conditions
*HINT: 5 T’s and 3 others
- Transposition of great arteries
- Tricuspid atresia
- Tetralogy of fallot
- Truncus arteriosus
- Total anomalous pulmonary venous return (TAPVR)
- Hypoplastic left heart syndrome
- Pulmonary atresia
- Ebstein’s anomaly
State the 7 types of acyanotic congenital heart disease
- ASD
- VSD
- Atrioventricular septal defect
- PDA
- Congenital aortic stenosis
- Coarctation of the aorta
- Pulmonary valve stenosis
Innocent/flow murmurs are very common in children; what are innocent flow murmurs caused by?
Fast blood flow through various areas of heart during systole
State 5 characteristic features of innocent/flow murmurs
- Soft
- Short
- Systolic
- Symptomless
- Situation dependent (e.g. gets quieter with standing, only appears when child is unwell or feverish)
Innocent/flow murmurs with no concerning features may not require further investigations; state some features that would prompt further investigation & referral to paediatric cardiologist
- Murmur louder than 2/6
- Diastolic murmurs
- Louder on standing
- Other symptoms e.g. failure to thrive, feeding difficulty, cyanosis, SOB
If a murmur in a child required further investigations, what investigations would you do? (3)
- ECG
- CXR
- Echocardiography
Where would you best hear a pan-systolic murmur due to a ventricular septal defect?
Left lower sternal border
What is an ASD?
State the 4 different types of ASD- put in order of most common
ASD is a hole in the septum between the two atria causing blood to flow from L to R
Types:
- Ostium secondum (septum secondum fails to fully close/ostium secondum fails to close. At level of fossa ovalis. 70%)
- Ostium primum (septum primum fails to fully close/fuse with endocardial cushions. Can be partial with intact ventricular septum and AV valves or complete with associated ventricular septal and AV valve defects)
- Sinus venosus: located near top of atrial septum and frequently associated with abnormal connection of pulmonary vein(s) to the RA instead of the LA
- Unroofed coronary sinus: atrial septal defect characterized by a deficiency in the tissue separating the coronary sinus from the left atrium (LA). This results in partial or complete unroofing of the coronary sinus leading to a predominantly left-to-right shunt through the coronary sinus
*remember septum secundum is on the right
What would you hear on auscultation of heart in pt with ASD? Include:
- What murmur you hear
- Where it’s heard loudest
- Mid-systolic, crescendo-decrescendo murmur with a fixed split second heart sound
- Heard best at upper left sternal border (pulmonary valve area)
Explain the pathophysiology of fixed split heart sound
- Fixed split heart sound= does not change with inspiration or expiration
- Occurs in ASD because blood is flowing from LA to RA increasing the volume of blood in RA and therefore the RV. This increases the volume of blood the RV has to empty before the pulmonary valve can close hence the pulmonary valve closes after the aortic vavle
Explain the pathophysiology behind splitting of the second heart sound in relation to inspiration
- During inspiration the chest wall moves outwards and upwards and diaphragm moves down causing a decrease in thoracic pressure (known as negative intra-thoracic pressure) to increase volume of lungs. This also increases volume of heart.
- This decrease in pressure causes blood to flow faster into RA from the venous system
- The increased volume in the RV means it takes longer for the RV to empty during systole
- This causes a delay in the pulmonary valve closing
- Pulmonary valve closes slightly later than aortic valve causing split second heart sound
ASDs are often picked up through antenatal scans or new-born examinations. May be symptomatic or asymptomatic in childhood. Asymptomatic children may become symptomatic as an adult. Discuss how an adult with an ASD may present
- Dyspnoea
- Heart failure (right sided)
- DVT leading to stroke (DVT embolises to RA, flow via ASD into LA, into LV, into aorta, up to brain causing stroke. If didn’t have ASD would have embolised in lungs causing PE. COMMON EXAM Q)
ASDs are often picked up through antenatal scans or new-born examinations; may be asymptomatic or symptomatic in childhood. State some potential symptoms of ASD in childhood
- SOB
- Difficulty feeding
- Poor weight gain
- Frequent LRTI
ASDs do not lead to cyanosis as blood continues to flow through pulmonary arteries to lungs to get oxygenated; however, it can have consequences for the right side of the heart. Discuss these consequences
- Blood flows LA to RA
- Increased flow of blood to right side of heart and through pulmonary arteries
- This can lead to hypertrophy and enlargement of pulmonary trunk
- Leading to pulmonary hypertension
- This can lead to RV hypertrophy and right sided heart failure
**Eventually if pulmonary hypertension increases so that pulmonary pressure > systemic pressure shunt may reverse- flowing R to L- and pt would become cyanotic (Eisenmenger syndrome)
What might you find on ECG of child with ostium secondum ASD?
What might you find on ECG of child with ostium primum ASD?
- Ostium secondum: RBBB with RAD
- Ostium primum: RBBB with LAD, prolonged PR interval
May have tall P wave (P pulmonale) in both due to right atrial enlargement
Is a patent foramen ovale a true ASD?
No!
There is a possible link between migraine with aura and PFO; true or false?
True
Discuss the management of ASDs
- Refer to paediatric cardiologist for ongoing management
- If small (<5mm) & asymptomatic can watch and wait
- Surgery if larger (>1cm) and/or symptomatic:
- Transvenous catheter closure
- Open heart surgery
- Diuretics if heart failure
- Anticoagulants (aspirin, warfarin & DOACs) used to reduce risk of clots & strokes in adults
State some potential complications of ASDs
- Stroke (DVT embolising)
- Atrial fibrillation
- Atrial flutter
- Pulmonary hypertension
- ^^ and right sided heart failure
- Eisenmenger syndrome
Remind yourself of the 5 steps of formation of the interatrial septum
- Endocardial cushions develop in atrioventricular region; growing from the dorsal and ventral surfaces then fusing in the midline
- Septum primum grows downwards towards (cranial to caudal) towards fused endocardial cushions. Before it fuses it forms a hole called the ostium primum.
- A second hole then forms in the septum primum, the ostium secondum before the ostium primum closes
- Ostium primum closes
- A second septum, septum secondum, then forms to the right of the septum primum; as it forms it creates a hole called the foramen ovale
What is a PDA?
What is the direction of blood flow through a PDA?
- Patent ductus arteriosus (fails to close in first 1-3 days)
- Aorta to pulmonary artery (down pressure gradient)
State some potential risk factors for PDA
- Prematurity
- Maternal infections e.g. rubella
- FH of congenital heart conditions
- Genetic conditions e.g. Down’s syndrome
- Born at high altitude
A PDA can be detected during newborn examination if a murmur is heard; what murmur is heard when there is a PDA and where is it heard best?
- Continuous crescendo-decrescendo ‘machinery’ murmur which may continue into 2nd heart sound making it difficult to hear. First heart sound is normal.
- 2nd ICS left (pulmonic area)
*****A patent ductus arteriosus causes a continuous murmur since there is a constant pressure gradient in both systole and diastole forcing blood from the aorta into the pulmonary artery
Alongside a continuous crescendo-decrescendo machinery murmur what else may you find on examination of pt with PDA?
- left subclavicular thrill
- large volume, bounding, collapsing pulse (due to low diastolic pressure as blood moves from aorta to pulmonary arteries)
- wide pulse pressure
- heaving apex beat
If the pda is small, the neonate/infant/child is often asymptomatic. However, if the PDA is larger then they may be symptomatic; state some potential symptoms of PDA
- SOB
- Difficulty feeding
- Poor weight gain/failure to thrive
- Frequent lower respiratory tract infections
A large PDA can cause signs of ____ soon after birth
Heart failure
*Smaller PDAs could also go undetected until adulthood in which they may still be asymptomatic or may present with signs of heart failure
Discuss potential consequences of a PDA (in regards to how it can impact the heart)
- Blood flows from aorta to pulmonary arteries
- Increased blood flowing through pulmonary arteries
- Increases pressure in pulmonary vessels causing pulmonary hypertension
- Leads to right heart strain and right ventricular hypertrophy
- Increased blood flowing through pulmonary vessels means there is increased blood returning to left side of heart leading to left ventricular hypertrophy
- Can therefore lead to heart failure
How is a PDA diagnosed?
- Echocardiogram to confirm diagnosis:
- Use of doppler flow studies can assess size & characteristics of L to R shunt
- Also useful for assessing impact of PDA on the heart
Discuss the management of a PDA
- Indomethacin or ibuprofen can be given to neonate to inhibit prostaglandin synthesis and promote closure
- Typically monitored until 1yr of age using echocardiograms; after 1yr highly unlikely it will close spontaneously so trans-catheter or surgical closure is done
- If symptomatic or evidence of heart failure, surgical correction is done earlier
- If associated with another congenital heart condition you may require the PDA to remain open therefore may give prostaglandin E1 until surgical repair of other abnormalities is appropriate
What is a VSD?
How common are they?
Ventricular septal defects are congenital holes in the septum between the two ventricles; size can vary from a tiny whole to the absence of an entire septum (meaning there is one large ventricle).
Most common type of congenital heart defect
VSDs may be detected in antenatal scans or if a murmur is heard during newborn examination; however, it may also present later in infancy/childhood. State some symptoms of VSD in neonates/infancy/childhood
The larger the VSD, the sooner the symptoms are noted. Moderate size usually obvious by 2-3 months as pulmonary vascular resistance increases due to shunting.
- Poor feeding
- Failure to thrive
- Sweating (due to increase sympathetic activity as compensation for decreased CO)
- Heart failure (tachypnoea, tachycardia, pallor, hepatomegaly)
- Frequent chest infections
Congenital VSDs can occur in isolation but are often associated with genetic conditions/syndromes; state some examples
- Genetic conditions/synrdromes:
- Down’s syndrome
- Turner syndrome
- Edward syndrome
- Patau syndrome
- cri-du-chat syndrome
- Holt-Oram syndrome
- Maternal diabetes mellitus (not gestational diabetes)
- Maternal rubella infection
- Fetal alcohol syndrome
- Family history
*Acquired causes include post-MI
The VSD murmur is ________ in smaller defects
VSD murmur is LOUDER in smaller defects
What murmur is heard when there is a VSD and where is it heard best?
What else may you find on examination?
- Pan-systolic (holosystolic) murmur
- Left lower sternal border (3rd and 4th ICS)
- May also find systolic thrill on palpation at lower left sternal border
*NOTE: if a neonate has large VSD
VSDs can occur in two parts of the ventricular septum; describe these
- Peri-membranous defects: occur in upper, membranous part near the valves (70%)
- Muscular defects: occur in lower, muscular section (20%)
State some differentials (other than VSD) for a pan-systolic murmur
- Mitral regurgitation
- Tricuspid regurgitation
Discuss the management of VSDs
- Referral to paediatric cardiologist (management is highly specialised)
- Small VSDs with no evidence of pulmonary hypertension or heart failure can be monitored as they 50% of VSDs close spontaneously
-
Moderate to large VSDs usually result in a degree of heart failure in first few months hence require:
- Nutritional support (e.g. NG feeds)
- Medication for heart failure (e.g. diuretics, ACE inhibitors, digoxin)
- Surgery (transcatheter closure or open heart surgery)
Discuss potential consequences of a VSD (in regards to how it can impact the heart
- Blood flows left to right through VSD
- Leads to increased blood volume in right side of heart and in the pulmonary vessels
- Increases blood volume in RV causes RV strain and hypertrophy which may lead to right sided heart failure
- Increased blood volume in pulmonary vessels can lead to pulmonary vessel hypertrophy and consequently pulmonary hypertension- this will increase RV strain
- Eisenmenger sydnrome may occur
State some potential consequences of VSDs
- Infective endocarditis (often given prophylactic abx before procedures)
- Eisenmenger syndrome
- Right sided heart failure
- Pulmonary hypertension
- Aortic regurgitation (due to prolapse of valve leaflet through defect)
*SIDE NOTE: pregnancy is contraindicated in pulmonary hypertension as it has 30-50% risk mortality
What is coarctation of the aorta?
Narrowing of the aortic arch, usually around the ductus arteriosus region. Severity can vary from mild to severe.
State some risk factors for coarctation of the aorta
Male
- Genetic conditions:
- Turner’s syndrome
- DiGeorge syndrome
- Hypoplastic left heart syn
Describe the effect of coarctation of the aorta on the blood pressure both distal and proximal to the narrowing
- Distal: pressure decreases
- Proximal: pressure increases
State some symptoms of coarctation of the aorta
State some signs of coarctation of the aorta
Often only indication of coarctation in neonate are:
- Weak femoral pulses
- High blood pressure in limbs supplied from arteries before narrowing, lower blood pressure in limbs supplied from arteries after
- May be a systolic murmur in left infraclavicular area and below left scapula
May have symptoms and signs such as:
- Poor feeding
- Grey & floppy baby
- Tachypnoea & increased work of breathing
Over time may develop….
- Left ventricular heave (due to left ventricular hypertrophy)
- Underdeveloped left arm if there is reduced flow to the left subclavian artery
- Underdevelopment of legs
What investigations are required for coarctation of aorta?
- ECG
- CXR
- Echocardiogram
Alongside characteristic murmur, what other signs may you find in congenital pulmonary stenosis?
- Palpable thrill in pulmonary area
- Right ventricular heave (due to RV hypertrophy)
- Raised JVP with giant a waves
What are the 4 abnormalities in Tetralogy of Fallot?
- Ventricular septal defect
- Overriding aorta (aortic valve/entrance to aorta is placed further to the right than normal)
- Pulmonary valve stenosis
- RV hypertrophy
Tetralogy of Fallot can be acyanotic or cyanotic; the degree of _____ mostly determines whether it is cyanotic or not?
Explain how Tetralogy of Fallot can lead to cyanosis.
Degree of pulmonary stenosis mostly determines whether it’s acyanotic or cyanotic. Greater degree of pulmonary stenosis, greater risk of cyanosis.
The aorta is overriding (placed further to right than normal) above the VSD; consequently, when the RV contracts and sends blood upwards the aorta is in the direction of travel of that blood (due to it being more to the right and VSD being present) hence some deoxygenated blood enters the aorta from the right side of the heart. The degree of pulmonary stenosis is what dictates how much deoxygenated blood goes into aorta as the greater the pulmonary stenosis, the greater the RV strain. RV strain causes RV hypertrophy which results in pressures in the right side of heart increasing and blood taking a ‘more left’ direction. More deoxygenated blood entering the aorta, greater the risk of cyanosis.
*Eventually Eisenmenger syndrome may occur
What are ‘tet spells’?
- Cyanotic episodes
- Child will also become irritable and hyperpnoea (increased resp rate & deeper breathing). May lead to reduced consciousness, seizures or death in severe cases
- Often precipitated by waking (as often kick their legs), physical exertion, crying or pooing
- Due to intermittent worsening of R to L shunt
- R to L shunt worsens when either pulmonary vascular resistance increases or systemic resistance decreases as Blood always takes path of least resistance
Example: when exercising a lot of CO2 is generated. CO2 is a vasodilator hence causes systemic vasodilation and decreases systemic vascular resistance. Increases R to L shunting of blood meaning more deoxygenated blood enters aorta and less deoxygenated blood enters pulmonary arteries to go to lungs
Summary of TOF
Explain why transposition of the great arteries is not a problem in utero
- Gas and nutrient exchange happens at placenta hence not necessary for blood to flow to lungs
- Oxygenated lungs flows from placenta, umbilical vein, ductus venosus, IVC, RA. Most then flows through foramen ovale into LA, LV and pulmonary arteries. Some flows into RV and then into aorta. Ductus arteriosus shunts blunt from pulmonary arteries into aorta. Hence, enough oxygenated blood still entering aorta.
What is tricuspid atresia?
Absence of tricuspid valve associated with hypoplasia of RV. Hypoplasia of RV occurs due to absence of inflow into RV due to absence of tricuspid valve.
What is hypoplastic left heart syndrome?
Underdevelopment of structures on left side of heart; it can affect a number of structures including:
- LV (underdeveloped and too small)
- Mitral valve (too small or not formed)
- Aortic valve (too small or not formed)
- Ascending aorta (underdeveloped or too small)
Often babies have ASD
What other congenital heart defects must be present for hypoplastic left heart syndrome to be viable?
- Patent foramen ovale or ASD: allow oxygenated blood returning to LA to shunt into RA then to RV then to pulmonary arteries
- Patent ductus arteriosus: allow mixed blood in pulmonary arteries to shunt into aorta via PDA (pressure in R > pressure in L due to hypoplastic heart and decreased volume???)
Discuss the management of hypoplastic left heart syndrome
Immediate/emergency treatments to allow mixing of blood
- IV prostaglandin E1 to keep ductus arteriosus patent
Surgery a few days after birth
- Norwood procedure (or hybrid if not suitable)
- *Norwood procedure involves separating the main pulmonary artery from the R and L branches. Then join the main pulmonary artery to the aorta. RV now supplies the aorta with mixed blood (as the ASD remains). A shunt is placed between the aorta and branches of pulmonary artery to provide mixed blood to the lungs. Hybrid uses a stent to keep PDA open and places small bands around left and right pulmonary arteries to reduce blood flow to lungs.*
What is pulmonary atresia?
Pulmonary valve has not formed therefore blood cannot flow from RV to the pulmonary artery. Need either ASD or VSD and a PDA; to allow blood from right side to flow to left side and be pumped out of heart then need PDA to allow blood to go to pulmonary arteries
Two types:
- Pulmonary atresia with intact ventricular septum: very little blood flows into RV hence remains very small and underdeveloped
- Pulmonary atresia with VSD: allows some blood to flow into RV from the LV so RV not as small or underdeveloped as with an intact ventricular septum
*image shows without VSD
What does TAPVR stand for?
What is TAPVR?
- Total anomalous pulmonary venous return
- Pulmonary veins don’t connect to the LA like usual; this can be partial/PAPVR (not all of veins have abnormal connection) or TAPVR (all veins have abnormal connection).
- Examples of abnormal connections:
- Supracardiac: connected to the SVC
- Cardiac: connected to RA
- Infracardiac: connected to veins of liver & IVC
- Have to have a patent foramen ovale or ASD to allow mixing of oxygenated and deoxygenated blood
What is truncus arteriosus?
What is the management?
- Blood vessel coming out of the heart in the developing baby fails to separate completely during development, leaving a connection between the aorta and pulmonary artery. Instead of having both an aortic & pulmonary valve they have a single truncal valve. Truncal valve is often thickened & narrowed which can impair blood flow from heart as well as leaking blood back into heart (regurgitation). There is usually a VSD aswell.
- Surgery (usually in first few months of life but depends how unwell child is): close VSD, use original single blood vessel to create a new aorta and use an artificial tube to connect RV to the pulmonary arteries
What are atrioventricular septal defects?
There are abnormal connections between left and right side of heart due to hole(s) in either the atrial septum, ventricular septum or both. The AV valves may also not be formed correctly.
- Complete AVSD: large hole in centre of heart allowing blood to flow between all 4 chambers of heart. One common AV valve (as opposed to two) and this common valve may not have formed correctly.
- Partial AVSD: a hole in either the atrial or ventricular septum near the centre of heart. Usually has both AV valves but one of them (usually the mitral) regurgitates.
*managed surgically
What is Ebstein’s anomaly? Include:
- Defect
- How this defect affects flow
- What other abnormalities associated with
- Tricuspid valve is set lower in right side of heart towards the apex causing a bigger RA and a smaller RV. Valve also leaks/regurgitates.
- Leads to poor flow from RA to RV and poor flow to pulmonary vessels
- Often associated with ASD (with _right to lef_t shunt); blood then bypasses lungs leading to cyanosis. And associated with Wolff-Parkinson-White syndrome.
For Eisenmenger syndrome, discuss:
- What it is
- Three underlying defects that can cause Eisenmenger syndrome
- How long it takes to develop
- Which population are at risk of quicker development of Eisenmenger syndrome
- Reversal of a left-to-right shunt in a congenital heart defect due to pulmonary hypertension
- Three defects: ASD, VSD and PDA
- If large shunt then can develop after 1-2yrs or may not develop until adulthood if smaller shunt
- Can develop more quickly in pregnancy hence women with hole in heart need an echo and close monitoring by cardiologist during pregnancy
