Left and right atrium are separated by septum called Inter atrial septum, which prevents mixing of deoxygenated blood coming from systemic circulation to right atrium with oxygenated blood coming from pulmonary circulation to left atrium.
ASD is congenital heart disease, in which there is hole or defect in inter atrial septum this leads to mixing of blood at the atrial level.
Blood from left atrium moves to right atrium, this is called left to right shunting. This is because right ventricle is more complained so it distends easily as compared to left ventricle.
Right atrium is overloaded with more blood, leading distention of right atrium, right ventricle and also pulmonary artery.
This increase flow on right side of heart leads following clinical signs
· Ejection systolic murmur at pulmonary valve.
· Fixed and wide splitting of second heart sound
· Mid diastolic murmur of tricuspid valve (Larger atrial septal defect)
Incidence of Atrial septal defect
1. 5 to 10 % of all congenital heart disease, as isolated anomaly
2. More common in females (male to female ratio 1:2)
3. ASD is associated with other congenital heart disease in 30-40% of cases
Types of Atrial septal defect
I. Ostium Secundum defect, most common 50-70% of all ASDs
II. Ostium primium defect, 30% of all ASDs
III. Sinus venosus defect, 10% of all ASDs
IV. Coronary sinus defect, rare variety of ASD
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| Types of ASD |
Electrocardiographic findings
Right axis deviation Mild Right ventricle hypertrophy with RBBB rSR’ pattern in lead V1 .
Chest X-ray
Cardiomegaly (enlarged heart), enlargement of Right atrium and ventricle and prominent pulmonary artery.
Echocardiography
This is most important investigation, which will detect ASD and helps in typing the ASD, and also gives valuable information in regard to weather given ASD needs closer by transcatheter (see below) approach or open heart surgery.
In older patients if trance thoracic imaging by Echocardiography is not proper some times, then patient may need trance esophagus echocardiographic study.
Echocardiography demonstrates
· Type of ASD
· Associated cardiac anomalies
· Size of ASD
· Rims around the defect whether they are good to hold ASD closer device
· Pulmonary artery pressure is estimated, if it is high then ASD cannot be closed.
Natural history of ASD
· Ostium secundum ASD have tendency to close by themselves
· Ostium secundum of less than 3mm in size detected within 3months after birth all of them ie 100% will close themselves within 1 and half year of age
· Ostium secundum of 3 – 8mm in size detected within 3months after birth 80% will close by themselves within one and half year of age
· Ostium secundum ASD of more than 8mm rarely close by themselves.
· Other type i.e. premium, sinus venosus type and coronary type do not close by themselves.
Symptomatic medical management
· Most children of ASD are asymptomatic
· Rarely develop heart failure in infancy
· Untreated large defect may lead to pulmonary hypertension at the age of 20 to 30 years
· ASD in adult may cause atrial fibrillation.
· No need for infective endocarditis prophylaxis
· Exercise restriction is unnecessary
Transe catheter closer of ASD
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| Transe catheter closer of ASD |
1. What is transe cathter closer of ASD ?
a. Done for Ostium Secundum ASD
b. In this procedure chest is not opened.
c. From anterior aspect of thigh through femoral artery device is delivered at the inter atrial septum
d. Patient is discharged with one or two days after procedure
e. Device used to plug the ASD are most commonly Amplatzer, Cardio seal, Sideris buttoned device, Angel wings device
2. Transe catheter closer is indicated in
a. ASD of size more than 5mm
b. Qp to Qs ratio (blood movement in right heart verses left heart ) more then 1.5 :1 (more the ratio suggest more shunting of blood from left to right heart.
c. Heart failure present in infancy
3. Rim around the defect has to at least 4mm in size, to hold the umbrellas of device, if not this procedure cannot be done.
4. Advantages of transe catheter closer are, no scar , very little pain i.e one injection in groin, 1 to 2 day of hospital stay, rapid recovery
5. Disadvantages little more chance of minimal residual shunt, compared to open heart surgery.
6. Post procedure
a. Aspirin 81mg/day for 6months
b. Echocardiography
i. Confirm no obstruction of pulmonary veins by device
ii. Confirm no obstruction of coronary sinus
iii. Confirm free movement of tricuspid and mitral valve leaflets
Open heart surgery
1. Done only in cases where rims of ASD can not hold device
2. Other types of ASD i.e. Ostium primium, Sinus venosus, Coronary sinus type are closed by open heart sugary.
3. Complication of open heart surgery
a. Less than 0.5% mortality for open-heart surgery for ASD
b. Sick sinus syndrome following surgical closer of sinus venosus defect
c. Cardiomegaly (enlargement of heart)
d. 7% to 20% may develop atrial arrhythmias
e. Residual shunt
