Congenital defects Flashcards
What is a Glenn shunt?
Stage 2 of Norwood procedure - direct connection between SVC and RPA for venous flow to lungs.
What condition is the Norwood procedure for?
Hypoplastic left heart syndrome
Tricuspid atresia
Double outlet right ventricle
In what spectrum does Hypoplastic left heart syndrome belong?
Hypoplastic left heart is in the spectrum of single ventricle defects that has a sequence of staged repairs.
Identify the different stages that can be involved
- Norwood - neonatal repair
- Bidirectional glenn repair - 6 months
- Fontan (3-4 yrs)
What is hypoplastic left heart syndrome?
Malformation of the LV (small) and aorta = can’t pump blood to the body
so the other ventricle (RV) not only pumps blood to the lungs, but also to the body.
Commonly, also have an ASD = mixing of blood
What occurs as a result of Hypoplastic left heart syndrome?
RV now has to pump blood to lungs and body via PDA (kept open by meds) = increased RV workload
Why is the ASD important in hypoplastic left heart syndrome?
ASD allows for left to right shunting of blood = mixing of oxy and deoxy blood.
Means RV also pumps little oxygenated blood to body via PDA
Why would a catherisation be important in hypoplastic left heart syndrome?
To make ASD bigger = more oxygenated blood to right side to be pumped to body
What is the purpose of the Norwood procedure?
Let’s the RV pump blood to body
What happens during the Norwood procedure?
Build a new larger aorta - bottom of PA joined to Ao = Ao goes from RV to body
Create a shunt to get blood to lungs = because PA now goes to body
Close the PDA
Make a bigger ASD = more oxygenated blood to RV
What kind of shunts can be used for a Norwood procedure?
Blaylock-Taussig-Thomas shunt
Sano shunt
What is the purpose of a Blaylock-Taussig-Thomas shunt?
moves blood from (and through) the aorta to the lungs.
What is the purpose of a Sano shunt?
moves blood from RV to PA then to lungs.
What does the Glenn procedure do?
Before Glenn - RV pumping blood to lungs and body = hard work
After Glenn: blood from upper body goes directly to lungs so RV doesn’t have to pump as hard
Why is a Glenn procedure required?
Because the shunts placed during the Norwood procedure require a more permanent solution
What happens during a Glenn procedure?
SVC disconnected from heart and connected to RPA = blood from upper body flows directly to PA into lungs
Shunt is removed, if Norwood procedure was performed
What is the purpose of the Fontan procedure?
No more mixing of oxygenated and deoxygenated blood
What is the outcome of the Fontan procedure?
The single ventricle:
only pumps blood to the body
only pumps blood with high oxygen to the body
What happens during the Fontan procedure?
IVC disconnected from heart and connected to PA via conduit
Fenestration (small hole) made between conduit and RA = allows blood to still blood into heart
What is the purpose of the fenestration made during Fontan procedure?
Prevents too much blood from flowing to lungs right away giving time to adjust.
Can be closed later during cath case
What is aortic stenosis?
when the aortic valve (the valve between the left ventricle and the aorta) is too small, narrow, or stiff.
What happens in aortic stenosis?
aortic valve controls direction of flow.
In aortic stenosis valve is narrow and small = cannot open all the way = LV has to work harder to push blood against abnormal valve = weakens heart
Treatment for aortic stenosis
Ballon valvuloplasty - balloon dilation of valve
Valve replacement - artificial or donor replacement of valve
What consideration are taken in choosing treatment for aortic stenosis?
the location and amount of the narrowing
age and size
how well the other valves in the heart are working
previous heart surgery
other medical conditions
What is an atrial septal defect (ASD)?
an abnormal opening in the dividing wall between the atria
What is the anatomy of CCTGA?
RV (weaker side) pumps to body
LV (stronger side) pumps to right side & lungs
- the RV was not built to last as long as the LV
What % of patients with CCTGA need pacemakers for complete heart block?
45%
How the RV affect prognosis of a person with CCTGA?
The ability of the RV to pump will determine how well a person with CCTGA is
Type of treatment for CCTGA is dependant on what?
Type and severity of symptoms
Associated defects
What are the most common problems in CCTGA?
VSD
Pulmonary stenosis
Leaky tricuspid valve
Heart block
What is the issue with ASD?
Left to right shunting of blood = increased blood flow to lungs
What considerations are taken when placing a PA band?
length of PA is sufficient to not impinge the Pulmonary valve, coronary arteries proximally or branch PAs distally.
What can be seen upon comparison of the MPA and the aorta during pulmonary overcirculation? Are there any risks involved?
MPA is larger in size than Ao
MPA can be thinned by dilatation
= increased risk of tearing
What is the pathophysiology of pulmonary overcirculation?
congenital defects with left to right shunting and unrestricted pulmonary flow due to drop in pulmonary vascular resistance
What is the consequence of pulmonary over circulation in the first year of life?
medial hypoertrophy of pulmonary arteriolds and fixed pulmonary hypertension
In patients with cardiac defects, what is the benefit of PA banding?
reduces shunt volume = improves systemic pressure and cardiac output
Decreased pulmonary blood flow = decreased blood to LV = improved LV function
What is the purpose of pulmonary banding?
creates a narrowing or stenosing of MPA = decreased blood flow to branch PAs = reduced pulmonary blood flow and PA pressure
In what patients is PA banding not tolerated?
patients with cardiac defects that depend on mixing of blood to maintain adequate Sats.
What what patients can PA banding be indicated?
VSDs
Coarctation of Ao
Single ventricle defects (tricuspid atresia)
Cardiac defects requiring homograft conduit
