Congenital diagnosis and management Flashcards
(148 cards)
Describe tricuspid atresia
Tricuspid valve never develops = no connection between RA and RV
Associated with ASD + large VSD + PDA
RV is hypoplastic (no flow no grow!)
Cyanotic
Describe circulation in tricuspid atresia
SVR enters RA, crosses ASD, mixes with PVR in LA, through MV (often hypoplastic) into LV
From LV, blood almost freely flows through VSD into hypoplastic RV
From the ‘common’ ventricles it can go to either (1) Aorta or (2) Pulmonary artery
Why is it ‘good’ to have PS in tricuspid atresia
We are ‘hoping’ for a concomitant degree of pulmonary stenosis, because pulmonary circulation is much lower resistance than systemic circulation, therefore if no PS there will be preferential blood flow into the pulmonary side
This worsens systemic perfusion and leads to pulmonary over-circulation, remodelling, and therefore pHTN.
Importantly, if pHTN develops, this would preclude Fontain palliation!!
On the other hand, if there is LV outflow tract obstruction this can also lead to systemic hypoperfusion and encourage preferential pulmonary circulation, similarly worsening the situation
Key management principles in tricuspid atresia
- Avoid too little systemic outflow
- Avoid pulmonary overcirculation
- Saturations and mixing of blood
Neonatal management of tricuspid atresia
Depends on principles of (1) managing the balance of pulmonary/systemic flow, and (2) managing O2 sats
- Maintain open duct - to improve pulmonary flow if there is excessive PS and therefore improve circulation to lungs
- Atrial septostomy - if no ASD, also to improve pulmonary flow if there is excessive PS and therefore improve circulation to lungs
- PA band - increase pulmonary vascular resistance and therefore essentially ‘create’ PS and avoid over-circulation to lung
Fontain Stage 1 timing and details
0-6 months
Norwood procedure
o Close PDA
o Create or widen ASD
o Create neo-aorta by re-rooting PV+proxPA into aorta - Damus-Kaye-Stansel (DSK) anastomosis
o Create new venous flow into PA with Blalock-Thomas-Taussig shunt (R SubC to PA) or Sano shunt (RV to PA)
End result of Stage 1 Fontan (Norwood procedure)
The heart pumps blood into one single common root
Blood flow to PA comes from a shunt from the aorta or RV
There is still atrial mixing
What are the BTT & Sano shunts
BTT - R SubC to PA
Sano - RV to PA
Fontan Stage 2 details
Bidirectional Glenn
o BTS/SanoS removed
o SVC cut above RA connection
o Connect SVC to PA directly
End result of Fontan Stage 2 (Bidirectional Glenn)
Blood flow to the lungs is now entirely via the SVC
There is still atrial mixing from IVC supply, but SpO2 improved
Fontan Stage 3 details
Usually at 2-5y
IVC connection to the pulmonary artery made
Extracardiac = SVC to PA, IVC to PA. RA is entirely bypassed
Total cavo-pulmonary conduit = connect SVC and IVC to PA; make a small fenestration in IVC to re-enter RA (to protect pulmonary circulation).
Close previous BT/Sano shunt
Classic Fontan risks
Massive RA dilation leading to significant atrial tachycardias; specifically intra-atrial re-entry tachycardia
High blood stasis leading to thrombus risk
In addition to normal Fontan, what did ‘Classic Fontan’ entail
Not done anymore
= connect RA to PA, and close ASD
List ASD types with %
- Secundum ASD (80%)
- Primum ASD (15%);
- Superior sinus venosus defect (5%)
- Inferior sinus venosus defect (<1%)
- Unroofed coronary sinus (<1%)
Shunting in ASD
ALL start as L>R shunt, with worsening RVF, these can reverse (R>L) = Eisenmenger’s
Secundum ASD
located in the region of the fossa ovalis and its surrounding (= patent foramen ovale)
Primum ASD
== atrioventricular septal defect (AVSD) with communication on the atrial level only. located near the crux, AV valves are typically malformed (total AV canal defect), resulting in various degrees of regurgitation.
Superior sinus venosus ASD
located near the superior vena cava (SVC) entry, associated with partial or complete connection of right pulmonary veins to SVC/RA`
Inferior sinus venosus ASD
located near the inferior vena cava (IVC) entry].
Unroofed coronary sinus ASD
separation from the left atrium (LA) can be partially or completely missing.
Typical history in ASD
- Often asymptomatic until adulthood
- Symptoms beyond 4th decade: exertional SOB, reduced functional capacity, RHF then cyanosis
Exam in ASD
- Ejection systolic murmur with fixed split S2 (inspiration and expiration)
- Cyanosis if shunt reversal
Investigation in ASD
Echo: quantify shunt volume and severity, size of ASD, TOE might be required for secundum defects (posterior) +/- CMRI
P Cath if suspicion of raised PAP +/- exercise testing if suspect PAH
o Can measure QpQs on cath using oximetry values using Fick principle
VO2 = (CaO2 - CvO2) * Q
Qp:Qs = (SatAorta-SatSVC)/(SatPulmonaryV- SatPulmonaryArt)
Management of ASD
- Optimize medical therapy
- If: RV overload or paradoxical embolism OR PAH, closure
- Eisenmenger’s is beyond possible closure – at that stage, closure of shunt will make patient sicker as it will further increase pulmonary pressures by closing the ‘outlet’ into the L side
- Patients who do not undergo closure have worse outcomes