Vignettes: Pediatric Cardilogy # 2

Vascular Rings:
I. True/ Complete:
i] Double aortic arch (aa)
ii] Rt aortic arch (aa) with aberrant Lt subclavian artery and ligamentum arteriosum (LA: formerly called the ductus arteriosus)
NB: Do we have Lt aortic arch with vascular rings? Yes, there are 2 rare such examples (not discussed here).
Lest you forget, 30 % pts of TOF have a rt sided aortic arch. This does not mean that they have vascular rings!

II. Incomplete:

a] Anomalous Innominate artery: Innominate branches further left from aa or branches more posteriorly.
b] Aberrant Rt subclavian artery: Rt subclavian arises from descending aorta.
c] Aberrant Lt pulm artery (rare)
NB: Brachio-cephalic was formerly called innominate artery.
Now, Double arotic arch:

i] Associated cardiac malformations: VSD, TOF, Truncus
ii] Syndromes: DiGeorge, VACTERAL, CHARGE
C/Fs: stridor, dysphagia

1. Cyanotic heart diseases:
"5 Ts Do ESP"
1. TOF
2. Tricuspid Atresia
3. TGA
4. TAPVC
5. Truncus Arteriosus
D : DORV (Double Outlet Rt Ventricle)
E: Ebstein
S: Single Ventricle
P: Pulmonary Atresia
2. Cg HD and radiological appearnace:
1. Boot shaped heart: TOF
2. Egg on string appearance: TGA
3. Snowman appearance (fluffy lung fields due to high PBF): TAPVC
4. Small heart on CXR (and increased PBF): Obstructive TAPVR
5. Masive cardiomegaly on CXR (and decreased PBF): Ebstein

3. Cg HD and operations:
1. Norwood: HLHS
2. Jatene (arterial switch): TGA
4. A way to remember:
RVH and decreased PBF: TOF
RVH and increased PBF: TGA, TAPVC, HLHS
Thus, 3 most common cyanotic CgHD are: TGA, TAPVC and HLHS and all 3 show RVH + Increased PBF
5.
10. Differential Dx of PDA:
Aorto-pulmonary window
i) AP window results from incomplete division of aorta and pulm artery during fetal life.
ii) Clinically, large window: As PVR falls, L --> R shunt would develop and would mimic PDA
Small window: May not be very symptomatic.
11. Think of:
Co Aorta: Turner Syndrome
IAA (Interrupted Aortic Arch): DiGeorge Syndrome
Note: IAA means interruption in aortic arch. Thus its clinical presentation may be similar to Co Aorta.
12. AV canal malformation reminds us of its association with Trisomy 21,ie, in Trisomy 21, AVC is seen.
Now what are the associated cardiac malformations which may be seen in pts of AVC: NeoR book says-
a] TOF in 10 % of pts
b] PDA in 10 % of pts
13. Norwood is done for HLHS.
a] Basis: Norwod is done in 3 stages:
1. Stage 1
2. Stage 2: Glenn
3. Stage 3 : Fontan
Now stage 1 : As we know in HLHS, the LV and Lt sided structures like aortic valve and aorta may be hypolpastic.
Thus there is decreased systemic output. The aim is increase systemic output.
* Atrial septectomy to prevent pulm venous congestion
* Create a single ventricle and send blood from here to both pulmones and systemic: How do we do it?
- If VSD is small, dilate it to make a single venticular chamber. If VSD is already bigger, it practically means that both ventricles make a single chamber.
-Cut MPA from its base and attach aorta here: Thus aorta now arises from RV and as we said, the ventricles are already a single chamber which you can call it to be practically Rt ventricle. Note: Aorta is generally hypoplastic in HLHS. Thus in actual, we cut PA and incorporate it in aorta to make a wider aorta: Neo-aorta.
- Now make a shunt between this neo-aorta and PA so that blood goes to lungs also. This shunt is called central shunt.
Alternatively, you can make a shunt between RV and PA: SANO Shunt this is called.

The end-result of stage 1:
There is only one ventricle (RV so as to speak), blood flows out from this single ventricle through Neo-aorta to systemic circulation and lungs( through aorta- PA shunt).
* From above physiology, we can understand one more concept:
Norwood stage 1-Post-operatively- how much O2 sats you will aim for:
Give just enough oxygen so that the baby should be maintaining SPO2 of 70 to 75 (i, PaO2 of 40). Not more than this.
Why: The single ventricle has to supply pulm and systemic blood and it should be in a ratio of 1: 1, ie, Qp and Qs should be 1: 1. If you give higher O2, it will result in pulm vaso-dilation ---> more pulm blood flow, lesser systemic output.
Stage II for HLHS: Bidirectional Glenn is done
As you know, after stage I, ventricles are essentially speaking single ventricle (RV).
In this intermediary procedure, aim is to decrease volume overload on RV until stage III can be done.
So what we do:
a] Shunt ( i assume it is aorto-pulm shunt) is removed.
b] Do Glenn, ie, Connect SVC directly to PA.
So what will happen: A bidirectional shunt allows flow to both RPA and LPA. This increases PBF without increasing volume load on RV.
Stage III: Modified Fontan
What is Fontan: Rerouting of SVC and IVC to PA bypassing the ventricles create separate systemic and pulmonary circulations.
NB: In order to do Fontan, pt must have normal PVR. It is unsuccessful in infants with raised PV resistance.
Note: Glenn and Fontan are the basic procedures for For TA (tricuspid atresia). TA is either corrected by Glenn at 4- 12 mo of age OR by Fontan at 1.5 - 3years of age.
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14. In AV canal malformations: ECHO may show "Goose Neck" sign. This is a typical board q.
15. TOF with VSD: PA are always of decreased size.
TOF with intact ventr septum: PA are of good size.
16. Factors which increase PVR (by vaso-constricting the pulm blood vessels): Dr IL-bawi's pet q
a] Hypoxia
b] Hper-carbia. NB: Hypercarbia causes pulm vaso-constriction but cerebral vaso-dilation.
c] acidosis
d] hypo-thermia
e] Pain
f] catecholamines: eg: epi,dopa,dobutamine
g] endothelin 1: produced by endothelial cells
h] Serotonin
17. Pulmonary vaso-dilators:
opposite of above factors( see q 16), and:
a] Viagra
b) PG
18. DKS( Damus Kaye Stansel):
Dr Ilb says that DKS is done to bypass inoperable AS. He further says that the DKS and Norwood are similar and infact, DKS is the basis of Norwood. In Norwood, infact we go much deeper into aorta, in DKS we donot.DKS is not done for PS.
What the book says about DKS:
a] indications:
Single ventricle with severe subaortic stenosis
DORV with a subpulmonic PS
TGA with severe RV outflow (aortic) obstruction
b] procedure: PA is transceted before the bifurcation,and main Pulm trunk is sewn into aorta. This enables the LV outflow to enter the original PA trunk and then aorta. A pulm homograft is sewn between RV and the pulm artey bifurcation.
19. Co Aorta may be present as a single lesion or in combination with other lesions such as VSD.
A bicuspid aortic valve is present in most pts with Co Aorta.