A 26–year–old Hispanic female without significant past medical history presented with new–onset diabetic ketoacidosis. She was admitted, and blood sugars and metabolic derangements quickly normalized with insulin and intravenous fluids. Physical examination on repeat assessment was notable for a systolic ejection murmur at the left upper sternal border with a prominent split of the second heart sound. She had no exertional symptoms, and denied any family history of congenital heart disease. Chest radiograph revealed mild enlargement of the right atrium and pulmonary arteries. Electrocardiogram demonstrated sinus tachycardia, with P wave morphology suggestive of right atrial enlargement. Transthoracic echocardiogram subsequently revealed an enlarged right atrium and right ventricle with diastolic interventricular flattening, consistent with volume overload. Injection of agitated saline confirmed the presence of a left–to–right intracardiac shunt, suggestive of an atrial septal defect (ASD). Transesophageal echocardiogram further demonstrated left–to–right shunting across a large secundum ASD. The patient was referred for outpatient percutaneous device closure.
ASD is an important diagnostic entity in the adult patient, with considerable morbidity and mortality if left unrepaired. Three quarters of ASDs are secundum defects, which are more common in women than men. Most ASDs represent spontaneous genetic mutations, though some are associated with heritable chromosomal abnormalities. Symptoms at presentation are nonspecific and most often include fatigue and exertional dyspnea. Long–term complications of uncorrected ASDs include atrial arrhythmias, right ventricular dilatation and failure, pulmonary hypertension, recurrent pulmonary infection, paradoxical embolism and cerebrovascular accident. Atrial fibrillation is rare in patients younger than 40, but there is an age–related increase in prevalence after age 40 which is independent of subsequent repair. Percutaneous device closure is standard of care for secundum ASDs in tertiary medical centers worldwide. Procedure efficacy has been demonstrated with experienced providers and appropriately selected defects. Compared with surgery, percutaneous closure is associated with a significantly lower risk of complication and has reduced hospital lengths of stay. Device closure of ASDs also affords significant improvement in exercise capacity, left ventricular filling, and cardiac output. Surgery remains first–line therapy in patients with specified defect complexities. Symptoms and evidence of structural right heart abnormalities are predominant indicators for immediate intervention.
ASD is a frequent congenital cardiac abnormality, the physiologic subtlety of which often results in the delay of diagnosis well into adulthood. The significant age–related morbidity and mortality associated with ASDs can be mitigated with timely defect closure, and is recommended in most patients regardless of age.