Ostium Primum Atrial Septal Defects Treatment & Management

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 owing to an inadequate inferior rim of atrial septal tissue and the proximity of the defect to the atrioventricular (AV) valves. In addition, the cleft in the mitral valve can’t be addressed by catheter intervention.

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

Prevention of congenital heart defects lies in continued research at the molecular genetics level. No effective preventive therapies are available at this time.

Low-risk patients with ostium primum atrial septal defects (ASDs) who undergo successful intracardiac repairs generally do well after surgery.

Immediately following surgery, patients usually receive intravenous (IV) diuretic therapy, traditionally furosemide. Fluid restriction is liberalized and diuretic therapy weaned over a period of 3-5 days postoperatively. Initially, electrolyte levels are closely monitored, with the frequency decreasing as diuretic therapy is weaned. During recovery, IV preparations are changed to oral (PO) formulations and the doses are decreased. Patients are typically discharged on twice-daily dosing. Diuretics are weaned over a period of weeks to months, dictated by physical findings and roentgenographic assessment.

Patients often require inotropic support and/or afterload reduction in the early postoperative period. Patients on preoperative angiotensin-converting enzyme (ACE) inhibition may remain on continued therapy for a period. As heart size and systolic function normalize, ACE inhibition may be reduced or discontinued in the outpatient setting. With persistent or evolving significant mitral regurgitation, afterload reduction should be continued.

Activity and diet are advanced. A postoperative transthoracic echocardiography is generally performed before discharge or at the first postoperative visit. Care must be taken to avoid trauma to the chest for 8-12 weeks postoperatively.

Some patients may develop a postpericardiotomy syndrome manifested by chest pain, fever, pericardial inflammation with a rub, and pericardial effusion. High-dose salicylates or nonsteroidal anti-inflammatory drugs (NSAIDs) generally improve symptoms. Hemodynamically significant effusions may require pericardiocentesis. Failure to respond to salicylates may warrant pulsed steroid therapy.

Diet and activity

For asymptomatic patients, no specific dietary recommendations are warranted. For infants or very young children with congestive heart failure (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 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. However, a right-to-left shunt and/or a significant pulmonary hypertension warrant(s) restriction to low-intensity competitive sports only (class IA). Note that 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 the systolic function is normal.

Definitive management of hemodynamically significant primum atrial septal defects (ASDs) and partial atrioventricular (AV) septal defects is operative repair. Its 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 of the repair 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 an 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, ministernotomy, and axillary approach. ^[19]

It is important to recognize that mitral valve cleft should be addressed at the time of surgery, irrespective of the degree of preoperative mitral insufficiency.

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; age at operation, preoperative grade of mitral insufficiency, and method of the cleft repair were not significant risk factors. ^[20] 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 transesophageal echocardiography (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 patients with a marked preoperative volume-overloaded heart. Inotropic support is important to avoid the tendency to volume resuscitate, which may result in dilatation 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 provide benefit in reducing AV valve insufficiency and increasing cardiac output.

Intraoperative TEE is requisite in all forms of AV septal 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 are inherent in all forms of congenital heart surgery and, thus, are also potential risks.

Follow-up is warranted within 1-2 weeks of surgery. At that time, assess the patient's vital signs, history, and physical examination, and remove sutures. In general, obtain an electrocardiogram (ECG) to rule out conduction abnormalities or arrhythmias. Perform chest radiography to evaluate potential pleural or pericardial fluid and to assess the heart size and pulmonary vasculature. Echocardiography may be performed as a limited study to assess function and effusion or on an inpatient basis as a complete postoperative study. Further outpatient care is dictated by findings from the initial visit.

Long-term follow-up is required for all patients. Both the tricuspid and mitral valves tend to be abnormal, with the potential for deterioration with advancing age. Postoperative prophylaxis against subacute bacterial endocarditis (SBE) is warranted for a minimum of 6 months, and it may be prudent for life because of the abnormal atrioventricular (AV) valve tissue adjacent to suture/patch material. The development and/or progression of AV conduction abnormalities also warrant continued observation. Late reoperations to address mitral regurgitation, mitral stenosis, or subaortic stenosis may be needed in 10 to 15% of patients. ^[21]

In patients who have not undergone repair for isolated small-to-moderate atrial septal defects (ASDs), follow-up in a clinic is usually every 6 months to 1 year. The presence of exercise intolerance, increasing fatigue, palpitations, and frequent lower respiratory infections or wheezing may merit referral for earlier repair. Palpitations may need to be evaluated with a Holter monitor and ECG. Chest radiography is warranted to follow heart size and pulmonary vascular markings.

For patients with mitral regurgitation, closer follow-up is usually necessary. In addition to the above, monitoring for progression of mitral regurgitation via physical examination, chest radiography, and echocardiography is important. It is essential to time surgery before a deterioration in ventricular function if ventricular dilatation is noted. Keep in mind that left ventricular function may appear near normal in the setting of moderate-to-severe mitral regurgitation because of the reduced afterload related to mitral regurgitation. Ventricular function may worsen significantly when a competent mitral valve is in place.