Atrial Septal Defects(ASD)

An atrial septal defect (ASD) is a deficiency of the atrial septum. ASDs account for about 10-15% of all congenital cardiac anomalies .
Types of ASDs:
1-Ostium secundum defect→70% of ASDs.
2-Ostum primum defect→20% of ASDs.
3-sinus venosus defect.→10%of ASDs.
4-coronary sinus septal defect→ < 1% of ASDs .

Cardiac Development:
Cardiac tissues are first detectable on the 18th or 19th day of fetal life. Cardiac development continues for the next several weeks. The atrial septum begins to form during the fourth week and is complete by the end of the fifth week.

Frequency:
Research indicates that the incidence of congenital heart disease (CHD) is 0.8% of the US population. Approximately 7% of these individuals, or about 1 in 1500 live births, have an ASD. An estimated 15-30% of healthy adults have an unfused foramen ovale in which the valve functions normally but has failed to fuse. I
PFO is of no haemodynamic significant and not considered as ASD. Does not need surgical repair but increase risk of paradoxical syst. embolization.

Age of presentation:
ASD, is present at birth; however, in most cases, a murmur is not audible until the child is a few months old. Symptoms usually do not occur in individuals with ASD until late childhood, adolescence, or adulthood.
Secundum type, sinus venosus, and unroofed coronary sinus defects sometimes are not diagnosed until the third decade of life.
Ostium primum ASDs usually are diagnosed in the first few years of life because of the presence of a mitral regurgitation murmur.

Ostium Secundum:
A defect in the region of the fossa ovalis
The most common form of ASD
Associated with structurally normal AV valves.
It may be single or multiple ( fenestrated atrial septum)
Female: male 3:1 incidence.
Associated lesions :partially anomalous pulmonary venous return .& Holt- Oram-syndrome.

Holt-Oram syndrome:
Holt-Oram syndrome (HOS) is a heart–upper limb malformation complex with an autosomal dominant inheritance.
Musculoskeletal defects:
    ♦Upper limbs are affected. The most severe form is phocomelia with rudimentary limbs.
     ♦Hypoplasia of the radius , The most common defects are radial thumb anomalies ranging from absent thumbs to displaced (distally placed), duplicated, or triphalangeal thumbs.
Atrial Septal Defects(ASD) ppt