An atrial septal defect is one of the most common forms of congenital heart disease found in adults. Although there are at least three different forms of atrial septal defect, they all have in common a communication between the right and left atrium. If the ASD is large enough, it produces enlargement of the right side of the heart, arrhythmias and sometimes pulmonary hypertension. In some patients, an ASD is discovered incidentally. In others, it can be suspected because of an abnormal cardiac exam, palpitations or shortness of breath. The diagnosis is generally confirmed with an echocardiogram. The three most common forms of ASD are: secundum, sinus venosus and primum defects.
The secundum defect is the most common form of ASD and generally occurs as an isolated defect. It results from failure of a part of the atrial septum to close completely during fetal development. In the past, surgery was required to close a secundum ASD. However, following the approval of the Amplatzer ASD closure device in 2002, most secundum defects can be closed with the catheter-based procedure. Click here for video.
The ASD closure device is inserted during a cardiac catheterization under echocardiographic guidance. Patients are discharged the following day on anti-platelet medications for six months. Unlike cardiac surgery, there is little or no recuperation associated with this procedure.
The primum ASD is a part of a larger spectrum of cardiac abnormalities known as an endocardial cushion defect. Endocardial cushion defects result in abnormalities of the atrioventricular valves, and both atrial and ventricular septum. A primum ASD refers to the hole in the inferior and posterior portions of the atrial septum adjacent to the AV valves. It is also associated with a cleft in the mitral valve which may result in a valve leak, known as mitral regurgitation. These defects require surgical repair which consists of patch closure of the ASD and repair of the mitral valve cleft. Greater surgical expertise is required to repair this defect because of the proximity to the electrical system of the heart and the mitral valve abnormality.
Sinus venosus ASD:
The sinus venosus ASD is located in the superior and posterior portion of the atrial septum. As a result, it can be more difficult to visualize with routine echocardiography. The defect is associated with abnormal drainage of one or more right sided pulmonary veins. Surgical repair involves patch closure of the ASD and redirection of the abnormal pulmonary vein back to the left atrium.
There are other less common forms of congenital heart disease that can cause similar symptoms and include partial anomalous pulmonary venous return and coronary sinus ASD. In both of these abnormalities, the clinical manifestations are related to the degree of excess blood flow into the right heart. Surgical repair is recommended when there are signs and symptoms of a significant increase of blood flow into the right heart
ASD closure eliminates the excess blood flow which produced enlargement of the right side of the heart. Pulmonary artery pressure may or may not be elevated in an adult with unrepaired ASD. Patients with mild or moderate degrees of pulmonary hypertension often experience improvement in pulmonary artery pressure following ASD closure. If pulmonary hypertension is severe, then ASD closure may not be advisable. Careful evaluation of patients with pulmonary hypertension should be performed to determine optimal management.
ASD closure also eliminates the potential for paradoxical embolization, a situation in which a blood clot can enter the systemic circulation from the right side of the heart and produce a stroke or damage to other organ systems. While exercise capacity is improved in many patients after ASD closure, arrhythmias, if present, may persist when surgery is carried out in older patients.
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