Interauricular communication is a congenital malformation characterized by a communication between the atrial chambers of the heart. Overall, openings between the atrial chambers account for about 6 to 8% of all congenitally malformed hearts. As a group, such defects are detected in 1:1500 live births, with a female-to-male ratio of 2-4:1. The estimated prevalence in the general population is 1 in 25,000. Not all communications between the atrial chambers of the heart represent deficiencies of the atrial septum, and the other forms of interatrial communication should also be recognized. There are four types of defect, named according to their position relative to the atrial septum. The ostium secundum defect is the most common type, accounting for three-quarters of all cases. The ostium primum defect, which accounts for one-sixth of defects, is in reality an atrioventricular septal defect, but with shunting exclusively at atrial level. The sinus venosus defect (one-tenth of cases) is a hole outside the confines of the oval fossa, and is associated with anomalous connection of the right pulmonary veins. The rarest defect, the coronary sinus defect, is found at the mouth of the coronary sinus, and is due to absence of the walls that usually separate the sinus from the left atrium. Clinical manifestations in childhood include: rapid breathing, shortness of breath, fatigue, sweating, palpitations, frequent respiratory infections, and poor growth. Other symptoms often manifest by the age of 30 to 40 years. Individuals with interatrial communications are at increased risk of developing infective endocarditis, hypertrophy of the right atrium and the right ventricle, pulmonary arterial hypertension (see this term), heart failure, arrhythmias, and stroke. Most defects occur sporadically as a result of spontaneous genetic mutations, but hereditary forms have been reported. About one third of affected children have an associated hereditary syndrome, such as Down's syndrome, Alagille syndrome, Holt-Oram syndrome, Ellis-van Creveld syndrome, or Noonan syndrome (see these terms). Several susceptibility genes have been identified. The defect is most often suspected during a physical examination. Cardiac auscultation reveals a systolic outflow murmur. Echocardiography, chest X-ray and electrocardiogram, and cardiac catheterization may help the diagnosis, although the latter technique is now rarely required for diagnostic purposes. A significant defect may be diagnosed during fetal life, although prenatal diagnosis is difficult as interatrial communication is an integral part of fetal circulation. Small-to-moderate defects may be asymptomatic and life expectancy is not reduced. In some children, small openings may close spontaneously (occurring in up to four-fifths of cases with small openings in the first 18 months of life). If there are few or no symptoms, or if the defect is small, it may not require closure. When the opening is large, or if symptoms occur, closure of the defect is recommended. Open-heart surgery used to be the technique of choice, and complication-free in the majority of cases. Nowadays, symptomatic defects can be closed by placement of a device introduced on a catheter, and this is the treatment of choice beyond the infant period.
Last update: April 2007