6. Structural Heart Defects Flashcards
What are structural heart defects?
Common Congenital Cardiac Malformations
Name a congenital heart defect that is cyanotic.
Tetralogy of Fallot.
Right to left shunt.
Name 3 congenital heart defects that are not cyanotic.
- VSD.
- ASD.
- PDA.
Left to right shunt! This is okay but a bit insufficient and there is a risk of Eisenmengers syndrome.
Explain the pathophysiology of Tetralogy of Fallot.
The stenosis of the RV outflow leads to the RV being at higher pressure than the left.
Therefore: ‘blue blood’ passes from the RV to the LV.
Aetiology of Tetralogy of Fallot?
Abnormalities in separation of truncus arteriosus into the aorta and pulmonary arteries early in gestation
What are the 4 main features of Tetralogy of Fallot?
1 - Ventricular septal defect (VSD)
2 - Pulmonary stenosis
3 - Right ventricle hypertrophy (RVH)
4 - Aorta overriding the VSD (over-riding aorta)
Think PROV:
Pulmonary stenosis
RVH
Overriding aorta
Ventricular septal defect
Describe the presentation of Tetralogy of Fallot.
Acyanotic at birth; gradually become cyanotic.
Tet spells.
Fallow (hypoxic) spells - go blue, restless.
Inconsolable crying.
Toddlers may squat.
Give 2 clinical signs of Tetralogy of Fallot.
- Left pulse weaker
- Clubbing
What is the characteristic feature of a CXR in Tetralogy of Fallot?
Boot shaped heart
Management of Tetralogy of Fallot.
For Tet spells:
- Long term beta-blockers
- Oxygen (100%)
- Knee-chest position + squatting
For acute episodes:
- Rapid intervention with morphine
Surgery at less than 12 months.
Would a baby born with Tetralogy of Fallot be cyanotic?
YES! There is a greater pressure in the RV than the LV and so blood is shunted into the LV -> CYANOSIS!
What is Ventricular Septal Defect (VSD)?
An abnormal connection between the two ventricles.
What are the 2 causes of VSD?
- Congenital
- Acquired post-MI
Explain the pathophysiology of VSD.
- High pressure LV.
- Low pressure RV.
- Blood flows from high pressure chamber to low pressure chamber.
- Therefore: NOT blue.
- Increased blood flow through the lungs.
Would a baby born with VSD be cyanotic?
No. There is a higher pressure in the LV than the RV and so blood is shunted from the left to right meaning there is an increased amount of blood going to the lungs; not cyanotic.
What is the difference between large VSD and small VSD?
Large: Very high pulmonary blood flow in infancy; requires fixing in infancy
Small: Small increase in pulmonary blood flow only; no intervention needed
How might a VSD present?
Severe heart failure in infancy.
OR - asymptomatic, detected later in life
Give 4 clinical signs of a large VSD.
- High pulmonary blood flow.
- Breathless, poor feeding, failure to thrive.
- Increased respiratory rate.
- Tachycardia.
What is seen on a CXR of someone with VSD (small and large)?
Small VSD - normal sized heart ± enlarged pulmonary blood vessels.
Large VSD - cardiomegaly (big heart), large pulmonary arteries, marked enlargement of pulmonary vessels.
Does a small VSD produce louder or quieter murmurs than a large VSD?
Louder
(loud pansystolic murmur)
What murmur is heard in VSD?
Harsh pansystolic murmur at left sternal edge, with systolic thrill
What can be heard for a VSD?
- Pansystolic murmur - loudest at the left lower sternal angle)
- RV heave / loud P2 (sound produced by the closure of the pulmonic valve)
Give 2 complications of a VSD.
Aortic regurgitation.
Infundibular stenosis.
IE.
Pulmonary hypertension.
Eisenmenger’s complex.
Management of a VSD.
Medical support until spontaneous closure.
OR - surgical patch repair or device closure.
What syndrome might VSD lead on to?
Eisenmengers syndrome.
What is Eisenmenger’s syndrome?
Cyanosis - clubbed and blue toes, pink not clubbed fingers.
Briefly describe the physiology of Eisenmengers syndrome.
High pressure pulmonary blood flow damages pulmonary vasculature -> there is increased resistance to blood flow (pulmonary hypertension) -> RV pressure increases -> shunt direction reverses (RV to LV) -> CYANOSIS!
What are the risks associated with Eisenmengers syndrome?
- Risk of death.
- Endocarditis.
- Stroke.
What is ASD?
An abnormal connection between the two atria (primum, secundum, sinus venosus).
It is fairly common.
Explain the pathophysiology of ASD.
- Slightly higher pressure in the LA than the RA.
- Shunt is left to right.
- Therefore: NOT blue.
- Increased flow into right heart and lungs.
What are the different types of ASDs?
Ostium secundum defects - most common - present in adulthood.
Ostium primum defects - associated with AV valve abnormalities - present early.
Sinus venosus defect - permits shunting of blood from the systemic to the pulmonary circulation and is commonly associated with anomalous pulmonary venous return - rare.
Would a baby born with ASD be cyanotic?
No. There is a higher pressure in the LA than the RA and so blood is shunted from the left to right, therefore not cyanotic.
Give 5 clinical signs of a large ASD.
- Significant increase in blood flow through the right heart and lungs - pulmonary flow murmur.
- Enlarged pulmonary arteries.
- Right heart dilatation.
- Shortness of Breath on Exertion (SOBOE).
- Increased chest infection.
- Fatigue, palpitations and syncope
What murmur is heard for an ASD?
- Pulmonary flow systolic murmur.
- Fixed split S2 second heart sound (delayed closure of PV because more blood has to get out).
What is seen on a CXR for an ASD?
Big pulmonary arteries.
Big heart.
Management of an ASD.
ASD repair surgery:
Open-heart surgery OR catheter-based repair.
Percutaneous -> key-hole surgery.
What is AVSD?
Atrio-ventricular septal defects. Basically a hole in the very centre of the heart.
Briefly explain the pathophysiology of AVSD.
Instead of 2 separate AV valves, there is 1 big malformed one.
It usually leaks to a greater or lesser degree
Give 2 clinical signs of AVSD.
- Breathless
- Poor feeding and poor weight gain.
What genetic disorder is associated with AVSD?
Downs syndrome
What structures are involved in an AVSD?
Atrial septum, ventricular septum, mitral and tricuspid valve
What are the clinical features and management of a partial AVSD?
Presents in adulthood, similar to small ASD/VSD.
Treatment not necessary.
What are the clinical features and management of a complete AVSD?
Breathless neonate, failure to thrive, poor feeding, torrential pulmonary blood flow.
Repair with PA band.
What is PDA?
Patent ductus arteriosus.
Briefly explain the pathophysiology of patent ductus arteriosus (PDA).
Persistent communication between left pulmonary artery and descending aorta - L to R shunt.
Normally: the ductus arteriosus closes within hrs of birth.
What are the clinical features of a PDA?
3 classic signs: bounding pulse, ‘machinery murmur’, pulmonary hypertension.
also - breathless, poor feeding, failure to thrive, Eisenmenger’s syndrome
Give 4 clinical signs of PDA.
- Torrential flow from the aorta to the pulmonary arteries can lead to pulmonary hypertension and RHF.
- Breathless.
- Poor feeding, failure to thrive.
- Risk of endocarditis.
Management of a PDA.
Indometacin (prostaglandin) can stimulate closure.
Surgical or percutaneous closure.
Local anaesthetic.
Venous approach (sometimes requires an AV loop).
What is coarctation of the aorta (CoA)?
Congenital narrowing of the descending aorta at the site of insertion of the ductus arteriosus
Describe the pathophysiology behind coarctation of the aorta.
Excessive sclerosing that normally closes the ductus arteriosus extends into the aortic wall leading to narrowing.
Describe the differences between mild and severe coarctation of the aorta.
Severe:
1. Complete or almost complete obstruction to aortic flow
2. Collapse with heart failure
3. Needs urgent repair
Mild
1. Presents with hypertension
2. Incidental murmur
3. Should be repaired to try to prevent problems in the long term
Give 4 clinical signs of coarctation of the aorta.
- Severe hypertension
- Radio-femoral delay
- Weak left radial pulse (if stenosis proximal to the left subclavian artery)
- Systolic vascular murmur
Treatment of coarctation of the aorta.
Surgery.
Percutaneous - balloon dilation ± stenting.
Give 3 complications of untreated CoA.
- Infective endocarditis
- Signs of heart failure
- Severe hypertension
Give 2 complications of CoA treatment.
- Recoarctation (recurrent coarctation).
- Aortic aneurysm.
- Pseudoaneurysm.
- Scar tissue.
What is a bicuspid aortic valve?
Normal AV has 3 cusps;
But - a bicuspid aortic valve has 2 cusps instead.
Give 2 differences between normal valves and a bicuspid aortic valve.
Bicuspid aortic valve:
1. Degenerate quicker than normal valves
2. Become regurgitant earlier than normal valves
Which 2 conditions is a bicuspid aortic valve associated with?
Coarctation of aorta
Dilatation of the ascending aorta
Give 4 complications of a bicuspid aortic valve.
- Aortic stenosis
- Aortic regurgitation
- Infective Endocarditis
- Aortic dissection
What is pulmonary stenosis?
Narrowing of the outflow of the RV
Give 3 clinical features of pulmonary stenosis.
- RV failure as neonate
- Collapse
- Poor pulmonary blood flow
- Right ventricle hypertrophy (RVH)
- Tricuspid regurgitation
Treatment of pulmonary stenosis.
Balloon valvuloplasty.
Open vavlotomy.
Open trans-annular patch.
Shunt (to bypass the blockage).
What investigations are used to diagnose most structural heart defects?
Echocardiography
Cardiac catheter.
