Tricuspid Valve Atresia Flashcards
What is tricuspid valve atresia (TVA)?
- Cyanotic heart lesion
- Characterised by congenital agenesis or absence of TV
Lesions associated with TVA?
- TVA
- Hypoplastic RV
- VSD
- Hypoplastic PA
- ASD (R-L)
- As a result, no communication between the RA and RV
- Therefore, must be R-L shunting of systemic venous return at atrial level across PFO or ASD for survival
TVA Classification
- 3 main classifications of TVA based on anatomic relationship of the great vessels
- Main classification sub classified depending on the:
1. Presence or absence of a VSD
2. Pulmonary stenosis or pulmonary atresia
What is type I TVA?
- Type I = normally related great arteries
- Type 1a = intact IVS with pulmonary atresia
- Type Ib = small VSD with PS or hypoplasia (most common type of TVA)
- Type Ic = large VSD without PS or atresia
What is type II TVA?
- Type II = d-TGA
- Type IIa = VSD with pulmonary atresia
- Type IIb = VSD with PS or hypoplasia
- Type IIc = VSD without PS or atresia
What is type III TVA?
Type III = l-transposition of great arteries (mal-position of great arteries/cc-TGA)
TVA: Associated CHDs?
- ASD (present in all cases)
- RV hypoplasia
- Aortic or subaortic stenosis
- CoAo or interrupted aortic arch
- Coronary artery anomalies
TVA: Circulatory Pathway in Type Ib?
- Deoxygenated blood from IVC/SVC –> RA –> blood shunted to LA across ASD where it mixes with oxygenated blood returning to LA via pulmonary veins
- From LA, desaturated blood travels to LV where majority of blood ejected into aorta and systemic circulation = marked cyanosis
- Small portion of blood shunted though restrictive VSD to small RV where it is ejected through hypoplastic PV to the lungs
TVA diagnosis on echo?
- Based on absence of TV as well as presence of ASD and RV hypoplasia
- Best identified in apical 4 chamber
- No TV; the only way RA can communicate with rest of circulation will be via ASD (R-L shunt)
Surgical repair for TVA?
Fontan connection / Fontan circuit
Aim of original Fontan connection surgery?
- Principle of procedure physiological rather than anatomical restoration of pulmonary blood flow with elimination of R and L-sided blood mixing
- Over time, found procedure resulted in RA dilatation which reduced propelling force of atrial contraction; and was associated with atrial arrhythmias and thrombus so further modifications made
Elements of Original Fontan Connection?
- RPA to SVC (Glenn shunt)
- Closure of ASD
- Pulmonary homograft into IVC
- Ligation of MPA
- RAA ro LPA (Atriopulmonary connection)
Total Cavopulmonary Connection (TCPC) in TVA repair?
- Nowadays TCPC op most common
- Includes bidirectional Glenn shunt or hemi-Fontan
- Plus redirection of systemic venous return to the PA via 1) an intra-atrial tunnel or 2) extracardiac conduit
- Operation increases pulmonary blood flow by diversion of systemic venous return directly to the PA i.e. blood flow bypasses the RV
What is the staged procedure approach for TVA?
- 3 different stages of Fontan operation in TVA as FOntan circulation is contraindicated in neo-natal period because of relatively high PVR
- Staged approach allows adaptations heart and lungs and reduced overall perioperative morbidity and mortality
Staged Fontan Operation: Stage One?
- First stage usually new-iron
- Artificial shunt placed between right subclavian artery and RPA
- Modified Blalock-Taussig shunt
Staged Fontan Operation: Stage Two?
- Second stage 2 - 6 months
- Anastamosis between RPA and SVC performed
- Glenn Shunt
Staged Fontan Operation: Stage Three?
- Third stage 1 - 5 years
- Completion ofFontan circulation
- Extracardaic conduit or intra-atrial tunnel
What is Fenestratred Fontan?
- In some patients, small fenestration approximately 4mm in diameter is created between conduit and atrium
- Fenestration acts a s a pressure release or ‘pop off valve’ allowing residual R-L shunt
- Limits caval pressure and congestion
- Allows increased preload os systemic ventricle
- Increased CO
- Desaturation
Goals of Echo: Fontan in TVA
- Assessment of Fontan pathway: 1) presence and size of fenestration, 2) presence and size of thrombus, 3) Fontan-to-PA anastomosis, 4) branch PAs
- LV systolic (+/- diastolic function)
- MV regurgitation (severity and mechanism)
- Aortic valve function
Significance of Fenestrated Flow?
Mean fenestration gradient = trans pulmonary gradient as it reflects pressure difference between Fonan and RA which connects to LA so it the pulmonary venous chamber
- Normal mean PG = 5- 8mmHg
- Abnormal mean PG > 10mmHg (due to increased PVR/thrombus/stenosis)
Complications: Fontan or TCPC?
- Ventricular dysfunction
- Pulmonary venous obstruction right pulmonary veins (due to RA dilatation)
- Systemic venous obstruction due to atriopulmonary connection stenosis
- Lateral tunnel stenosis, SVC stenosis, peripheral PA stenosis
- RA and conduit thrombus
