Atrial Septal Defect, Ostium Primum Treatment & Management

Catheter intervention: Unlike a ostium secundum atrial septal defect (ASD), the ostium primum form of ASD is not amenable to device closure in the cardiac catheterization laboratory. The device is unable to be adequately seated secondary to an inadequate inferior rim of atrial septal tissue and the proximity of the defect to the atrioventricular (AV) valves.

Definitive management of hemodynamically significant primum ASDs and partial AV canal defects is operative repair. Timing has been debated over the years; more recent reports encourage a trend toward earlier repair.

• Patients with an isolated ostium primum ASD are typically referred for elective repair between the ages of 2 and 5 years. Occasionally, repair may be recommended at an earlier age because of significant congestive heart failure (CHF) or failure to thrive, especially if associated with significant mitral regurgitation. Repair is preferred in patients younger than 10 years to decrease the risk of persistent atrial arrhythmias or pulmonary vascular disease in later life.
• The most important consideration in timing is the incompetency of the mitral valve. Once regurgitation develops, the leaflets tend to thicken, making valve repair less successful. Most surgeons prefer referral upon presentation of all patients with documented mitral regurgitation, regardless of symptoms, because earlier age of repair has been shown to reduce the development of late mitral regurgitation. Recurrent severe mitral regurgitation may require further reconstruction of the mitral valve and/or eventual prosthetic mitral valve replacement, with its inherent anticoagulation risks.
• Adults have tolerated surgery well as a whole. Case reports of surgical repair as late as the seventh decade of life have documented successful outcomes and a notable improvement in symptoms. Pulmonary hypertension and elevated pulmonary vascular resistance do not appear to be contraindications and generally improve postoperatively. A small but significant number of adults develop long-term difficulties despite repair. These difficulties generally include atrial arrhythmias, complete heart block, subaortic stenosis, recurrent mitral regurgitation, and mitral stenosis. Long-term follow-up is requisite.
• Repair is performed through a right atrial incision. The mitral valve is repaired first through the ASD. Complete repair of the cleft is preferred, moving the sutures centrally from the annulus until chordal attachments are reached (bifoliate approach). Central regurgitant jets are addressed by placing sutures at the bases of the commissures to reduce the annulus circumference. The ASD is then closed with a pericardial patch. Successful primary suture closure of smaller primum ASDs has been reported. Less invasive surgical access has been utilized with success, including a transxiphoid approach, right submammary minithoracotomy, and ministernotomy.
• Symptomatic patients with severely malformed valves and significant preoperative mitral regurgitation often have less optimal long-term results than those patients with competent mitral valves. Results have improved with more aggressive attempts at complete closure of the mitral cleft, bearing in mind that mitral stenosis is a poorly tolerated alternative. A Japanese study noted postoperative mitral regurgitation grade II or higher at hospital discharge to be the only independent variable related to late mitral regurgitation;^[1] age of operation, preoperative grade of mitral insufficiency, and method of repair of the cleft were not significant risk factors. Efforts to eliminate even mild postoperative mitral regurgitation were encouraged. Late development of moderate-to-severe mitral regurgitation warrants repeat mitral valve repair or, occasionally, mechanical valve replacement.
• Other patients at risk of reoperation include those with left ventricular outflow tract obstruction that is related to accessory mitral chordal attachments to the interventricular septum or to muscular subaortic stenosis from the inherent "gooseneck" deformity of the sprung aorta. Late mitral stenosis is a rare, late cause of reoperation, with its incidence reduced by routine use of intraoperative TEE. Severe associated defects, particularly those with aortic arch abnormalities, may also warrant further repair.
• Systolic function may be depressed in the immediate postoperative period in the patient who has a marked volume-overloaded heart preoperatively. Inotropic support is important to avoid the tendency to volume resuscitate, which may result in dilation of the mitral annulus and worsening of mitral valve regurgitation. Diuretics and judicious fluid use are beneficial, as atrial-filling pressures should be kept low. Afterload reduction may be helpful. Some patients, particularly those with trisomy 21 may develop a junctional escape rhythm postoperatively. Atrial pacing restores AV synchrony and may be beneficial to reduce AV valve insufficiency and increase cardiac output.
• Intraoperative TEE is requisite in all forms of atrioventricular canal defects. Important information is gleaned with respect to residual atrial level shunting, residual mitral regurgitation, the presence of new or worsening mitral stenosis, and potential left ventricular outflow tract obstruction. The risk-to-benefit ratio of performing TEE must be weighed in the setting of a tenuous airway, gastroesophageal abnormalities, or prior surgeries.
• Complications related to cardiopulmonary bypass and anesthesia inherent in all forms of congenital heart surgery also are potential risks.

Consultation with a geneticist is advisable for children with trisomy 21 or any suspected chromosomal abnormality or syndrome.

For asymptomatic patients, no specific dietary recommendations are warranted. For infants or very young children with CHF, caloric supplementation may be needed. Despite pulmonary overcirculation, it generally is not advisable to fluid-restrict children with CHF who are able to feed orally. Adequate intake of fluids must be maintained in order to achieve caloric goals. Fluid intake can be balanced with diuresis to offset volume overload.

• No activity restriction is imposed on patients with small defects and without evidence of pulmonary hypertension.
• A right-to-left shunt and/or a significant pulmonary hypertension warrant restriction to low-intensity competitive sports only (class IA).
• Associated mitral regurgitation may affect exercise recommendations.
• No restriction is placed on patients in sinus rhythm with normal left ventricular size. However, mild ventricular enlargement warrants restriction of low and moderate static and dynamic competitive sports, provided systolic function is normal.