1. Dr. M. A. Sofi MD; FRCP (London); FRCPEdin; FRCSEdin
ATRIAL SEPTAL DEFECT
Dr. M. A. Sofi
MD; FRCP (London); FRCPEdin; FRCSEdin

2. Atrial septal defect
Atrial septal defect is characterized by a defect in the interatrial septum allowing pulmonary venous return from the left atrium to pass directly to the right atrium.
Depending on the size of the defect, size of the shunt, and associated anomalies, this can result:
No significant cardiac sequelae
Right-sided volume overload
Pulmonary arterial hypertension
Atrial arrhythmias.
The subtle physical examination minimal symptoms during the first 2-3 decades contribute to a delay in diagnosis until adulthood
Majority (more than 70%) of which is detected by the fifth decade.

3. Atrial septal defect Frequency
The 3 major types of atrial septal defect (ASD) account for 10% of all CHD and as much as 20-40% of congenital heart disease presenting in adulthood
Ostium secundum: The most common accounting for 75% of all ASD cases
Ostium primum: The second most common accountinfgfor 15-20% ASDs
Sinus venosus: The least common of the three, accounting for 5-10% ASDs
Sex: female-to-male ratio of approximately 2:1.
Age: Patients with ASD can be asymptomatic through infancy and childhood
Timing of clinical presentation depends on the degree of left-to-right shunt.
By the age of 40 years, 90% of untreated patients have symptoms of
Exertional dyspnea
Fatigue, palpitation
Sustained arrhythmia
Heart failure

4. Clinical presentation
ASD malformation can go undiagnosed for decades
Isolated defects of moderate-to-large size may also be asymptomatic
All patients with ASD beyond the sixth decade are symptomatic.
Clinical deterioration in older patients results from:
Age-related decrease in LV compliance augments the left-to-right shunt
Atrial arrhythmias, especially AF, atrial flutter or PAT, increase in frequency after the fourth decade and can precipitate right ventricular failure
Adults older than 40 years have mild-to-moderate pulmonary hypertension in the presence of a persistent large left-to-right shunt; the right ventricle is burdened by both pressure and volume overload.

5. Clinical presentation
Significant mitral regurgitation is associated with septum primum ASD
Its incidence, extent, and degree of dysfunction increases with age.
Mitral valve insufficiency leads to further increase in left atrial pressure and a higher degree of left-to-right shunt.
Most common presenting symptoms include:
Dyspnea
fatigability
Palpitations
Arrhythmia
Syncope
Stroke
Heart failure

6. Physical: Depend on the degree of left-to-right shunt
Hyperdynamic right ventricular impulse due to large stroke volume
Pulsation of the pulmonary artery and an ejection click can be detected
S1 is typically split, and increased in intensity second component
S2 is often widely split and fixed
Systolic ejection murmur in the second intercostal space
Ostium primum defect an apical systolic regurgitant murmur of mitral regurgitation may be present.

7. Treatment
The decision to repair any kind of atrial septal defect (ASD) is based on clinical and echocardiographic information
The size and location of the ASD
Hemodynamic impact of the left-to-right shunt
The presence and degree of pulmonary arterial hypertension
Elective closure is advised for all ASDs with right ventricular overload or with a clinically significant shunt
The widespread use of catheter closure of secundum ASD with lower mortality has raised the question regarding the need to close even small defects

8. Contraindications to surgical repair
Closure of ASD is not recommended in patients with a clinically insignificant shunt
Those who have severe pulmonary arterial hypertension or irreversible pulmonary vascular occlusive disease
Those who have a reversed shunt with at-rest arterial oxygen saturations of less than 90%.
In addition to the high surgical mortality and morbidity risk, closure of a defect in the latter situation may worsen the prognosis.
Those patients whose condition is diagnosed well in the sixth decade of life would benefit from surgical closure remains controversial.

9. Laboratory Studies
Routine laboratory studies should be performed in patients undergoing intervention for ASD: Complete blood count/LFT/TFT/BUN/
Metabolic profile or chemistry
Coagulation studies (prothrombin time [PT] and activated partial thromboplastin time [aPTT])

10. Imaging Studies Chest radiography may reveal:
Cardiomegaly because of dilatation of the right atrium and right ventricular chamber.
Prominent Pulmonary artery and pulmonary vascular markings
Left atrial enlargement is rare only if clinically significant mitral regurgitation
Dilatation of the superior vena cava can be seen in sinus venosus defect.
Transthoracic and Trans esophageal echocardiography can provide excellent definition of the atrial septum.
TEE is also useful in guiding device placement during catheter ASD occlusion procedures and in providing immediate intra- operative assurance that defect closure is accomplished.