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

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.

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

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.

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

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.

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

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.

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])

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.