Atrial septal defects

Question 1

List 3 main types of ASD

Answer 1

Ostium Secundum (80%) 
Ostium Primum (10%) 
Sinus venosus (10%) 

Other 3 types
Common single atrium
Unroofed coronary sinus
Patent foramen ovale

Question 2

What is Ostium Secundum

Answer 2

Confined to the region of the fossa ovalis
Result from a deficiency of the septum primum to adequately close the foramen ovale
Defect size ranges from a pinhole to a larger

Question 3

What is Sinus venosus

Answer 3

Typically at junction between the SVC and RA
Located in posterior in the septum and above the superior limbic band (the superior rim of the fossa ovalis
*common association with anomalous drainage of the RSPV
RSPV tends to enter the LA at the junction of the SVC and RA along the right margin of the ASD.
Rarely ASD can occur adjacent to the IVC and be associated with anomlaous RIPV drainage

Question 4

What is Ostium Primum

Answer 4

Crescent-shaped defect in inferior septum immediately adjacent to atrioventricular valves
Also considered a partial/incomplete AV canal defect
Frequently asso with cleft in anterior MV leaflet (+/- MR)

Question 5

What is unroofed coronary sinus

Answer 5

Direct communication between the coronary sinus and the LA
Blood drains from LA through CS into the RA
No actual opening in the septum
Frequently a left superior vena cava draining into coronary sinus (or sometimes LA)

Question 6

Pathophysiolgy of ASD

Answer 6

Degree of shunting dependent on ASD size and ventricular compliance
Normally PL > PR and RV more compliant so you get Left to Right shunt
Causes RV dilation and excessive pulmonary flow
Generally not cynaotic (only if common atrium and unroofed CS)

Question 7

What is clinical course

Answer 7

If significant develop RV dysfunction, Pulmonary hypertension, CHF, and usually death (often early in 3rd decade)
Defects < 4 mm will usually close
Defects > 8 mm are unlikely to close
Closure of any ASD after age 4 is unlikely
Isolated ASD is not a risk factor for IE

Question 8

List physical signs of ASD

Answer 8

Audible murmur is that of physiologic pulmonic stenosis (increased flow over PV
ECH will show RVH, RAD
ECHO is needed
10% need a cath to look for anomalies, document pressures
Common to have a 10 to 30mmHg gradient over PV

Question 9

What are the CCS 2009 guidelines for closure of ASD

Answer 9

Should be closed in the presence of hemodynamically significant ASD with or without symptoms
A large ASD is greater then 38 mm and this should be closed surgically
If pulmonary hypertension is present and reversible
Qp:QS shunt of 1.5

Question 10

What are the European Class I indication for close of ASD

Answer 10

1) Patients with significant shunt (signs of RV overload) and a PVR < 5 should undergo closure regardless of symptoms
2) Device closure is the method of choice

IIa
1) Regardless of size with suspicision of pardoxical embolism

Question 11

What are indications to close ASD

Answer 11

Physical symptoms of CHF
Qp/Qs > 1.5 to 1. Almost all will have this if they physical signs or fixed S2
Close ASD prior to child starting school

Question 12

How is pulmonary vasculature overload tolerated

Answer 12

Usually pretty well (for many yers)
25% develop PHTN (with PAS > 30mmHg)
Can still develop obstructive pulmonary vascular disease
Increased PVR by 10%
Can develop Eisenmenger’s syndrome
Most common cause for late mortality is CHF and arrhythmias

Question 13

What is most common complication of transcatheter closing of ASD

Answer 13

Most common complication with device closure are malposition and dislocation
Good results when patients are selected appropriately
only adequate when there is an achoring rim

Question 14

What are results of Ostium secundom defect closure

Answer 14

Excellent
Very low peri-operative MandM
Long-term survival is equal to that of age-matched cohort
Very rare to need re-operation

Question 15

What are oucomes for Sinus venosus defects

Answer 15

SVC and RSPC stenosis is < 10%
Sinus dysfunction is about 7%
rare to need a PPM

Question 16

What are unique features to watch for post Ostium Primum defect repair

Answer 16

MV regurgitation
AV block requiring PPM 
LVOTO 
Overall re-op rate is about 10% 
Mortality is 1.5%

Question 17

When should you not close an ASD

Answer 17

1) PAH (PAP greater then 2/3 the systemic artery blood pressure,
2) pulmonary artery resistance greater then two thirds the systemic arteriolar resistance and irreversible

Question 18

What is latest percutaneous evidence for closure of ASD to prevent paradoxical CVA

Answer 18

NEJM 2012–paper

In patients with cryptogenic stroke or TIA who had a patent foramen ovale, closure with a device did not offer a greater benefit than medical therapy alone for the prevention of recurrent stroke or TIA at 2 year follow-up

Question 19

What is rate of successful closure of PFO with a percutaneous device

Answer 19

85-90%

Question 20

List syndromes associated with Left to Right shunts of a PFO

Answer 20

Paradoxical thromboembolism 
Paradoxical gas embolism and decompression illness
Migraines with Aura
High Altitude sickness
Artery hypoxemia

Question 21

What is prevalence of PFO in general population? and % that of these PFO that are large

Answer 21

25% of population may have a PFO with only 7% of these being significant

Question 22

What are contraindications for cath based closure of ASD

Answer 22

.

Question 23

What are class I indications to close a VSD

Answer 23

1) Presence of significant VSD
symptomatic, LV volume overload, Qp:Qs 2:1; pulmonary artery systolic pressure ? 50mmhg;
2) Significant RVOT gradient > 50mmHg
3) A perimembranous or subarterial VSD with more then mild aortic incompetence
4) Severe pulmonary hypertension greater then 2/3rd the SABG

*The Class IIb are: history of endocarditis, transvenous pacing, prevent paradoxical emboli; other associated lesions are being closed.

Question 24

What is incidence of ASD

Answer 24

1/1500 births
10% of congenital lesions
2:1 ratio of female to male