Tetralogy of Fallot Flashcards
What is Tetralogy of Fallot?
Most common cyanotic congenital heart disease
What is the pneumonic to remember Tetralogy of Fallot?
PROVe
What is Tetralogy of Fallot made up of? (4 things)
- Pulmonary Stenosis
- RV hypertrophy
- Overriding aorta
- Ventricular septal defect
(PROVe)
What is the prevalence of TOF?
3-6 in every 10,000 births
What does Overriding aorta mean? (2 points)
- Aorta entrance (aka aortic valve) more to R than normal
- So it’s right above VSD
What does Overriding aorta mean? (2 points)
- Aorta entrance (aka aortic valve) more to R than normal
- So it’s right above VSD
What is having Overriding aorta in TOF bad? (2 steps)
- When RV contracts –> send blood upwards
- More deoxygenated blood enters Aorta from R heart
Why is Pulm Stenosis bad in TOF? (2 steps)
- PS –> increased resistance against blood flow from RV
- Encourages deox blood to flow thru VSD –> Aorta (instead of thru pulm vessels to lungs)
Therefore, what phenomena does Overriding aorta + PS contribute towards?
- R-L shunting –> Cyanosis
- How do you get RV hypertrophy in TOF?
- RV straining to pump blood vs Pulmonary Stenosis
What are the RF for TOF? (5 things)
- Male
- Rubella
- Maternal age 40+
- Maternal DM
- Alcohol @ pregnancy
How are TOF Dx picked up early? (2 things)
- Antenatal scans (most cases Dx here)
- Newborn baby checks (will hear Ejection systolic murmur from PS)
What are the CF of TOF? (5 things)
- Cyanosis
- Clubbing
- Poor feeding / X weight gain
- Ejection systolic murmur
- Tet spells
Where will the Ejection systolic murmur be loudest?
In Pulmonary area
What are Tet Spells?
Episodes where R-L shunt becomes temporarily worse –> Cyanosis episode
What is the pathophysiological reason for a Tet Spell? (2 things)
- Pulm vasc resistance increases // OR //
- Systemic resistance decreases
What things can cause Tet Spells? (3 things)
- Waking up
- Physical exertion
- Crying
How can physical exertion cause a Tet spell? (6 things)
- CO2 produced @ exercise
- CO2 = vasodilator –> Systemic vasodilation
- Systemic resistance decreased
- Blood flow prefers low resistance path –> R-L shunting increases
- Deoxyg blood flows from RV –> Aorta (instead of Pulm vessels, so bypasses lungs)
- Cyanosis
What are the CF of a Tet Spell? (3 things)
- Irritable
- Cyanosis
- SOB
What can severe Tet Spells lead to? (3 things)
- LOC
- Seizures
- Death
What is the GOLD standard investigation for TOF Dx?
Echocardiogram
What investigations should you for do for sus TOF? (2 things)
- ECG
- Bloods
What will an ECG show you in TOF?
R axis deviation / RVH signs
When should you do Bloods in sus TOF?
When sus chromosomal abn
What imaging should you do for sus TOF? (2 things)
- Echocardiogram (GOLD)
- CXR
What will a CXR show you in TOF? (2 things)
- Boot shaped heart (RVH)
- Reduced pulm vasc marking (bc less pulm blood flow bc shunt)
What are the CONSERVATIVE Mx options for TOF?
Squatting / knees to chest
(infants do it by themselves, n parents should do it for them as well)
Why do TOF kids squat / bring knees to chest?
It increases venous return –> increases Systemic resistance
What are the MEDICAL Mx options for TOF? (5 things)
- O2 (if hypoxic in Tet Spell)
- Prostaglandin infusion
- Beta blockers
- Morphine
- Saline 0.9% bolus
How does Prostaglandin infusion work in TOF Mx? (2 steps)
- Maintains PDA (patent ductus arteriosus)
- Allows blood to flow bk from Aorta –> Pulm arteries
When should Prostaglandin infusions be started for TOF?
Immediately after delivery
(to avoid newborn collapsing)
What are the Side fx of Prostaglandin infusions? (3 things)
- Apnoea
- Bradycardia
- Hypotension
How do Beta blockers work in TOF Mx? (2 steps)
- Relax RV
- Improves flow to Pulm vessels
When can Beta blockers also be used during?
Tet spells
What Beta blocker is commonly used in TOF?
Propranolol
How does Morphine work in TOF Mx? (2 steps)
- Increases resp drive
- Reduces Hyperpnoea –> more effective breathing
How does Saline 0.9% bolus work in TOF Mx? (2 steps)
- Increase pre-load
- Increases volume of pulm blood flow
What are the SURGICAL Mx options for TOF?
- Temporary procedure (to reduce shunt)
- Definitive procedure
What does the Definitive Surgery for TOF involve? (2 things)
- Enlarging PS
- VSD patch
What are the complications of TOF? (6 things)
- Polycythaemia
- Cerebral abscess
- Stroke
- Inf endocarditis
- CHF
- Death
What is the rate of death in TOF in 1st year of life?
25%
What complications can post TOF surgery pt develop in long term? (4 things)
- Pulm regurg (PR) (common)
- Arrhythmias
- Exercise intolerance
- Sudden death
