From the Guidelines
Isolated ostium primum defects account for approximately 15-20% of all atrial septal defects (ASDs). This type of defect occurs in the lower portion of the atrial septum, adjacent to the atrioventricular valves, and represents an incomplete fusion of the endocardial cushions during embryonic development. Unlike other forms of ASDs, ostium primum defects are often associated with abnormalities of the mitral valve, particularly a cleft in the anterior leaflet, which can lead to mitral regurgitation. These defects are more common in individuals with Down syndrome, with approximately 40% of Down syndrome patients who have congenital heart disease presenting with an atrioventricular septal defect, which includes ostium primum defects. The clinical significance varies depending on the size of the defect and associated valve abnormalities, with larger defects causing more significant left-to-right shunting of blood and potential for pulmonary hypertension if left untreated. According to the 2018 AHA/ACC guideline for the management of adults with congenital heart disease 1, ostium primum ASD is classified as a moderate complexity defect. Management typically involves surgical repair, ideally before the development of pulmonary hypertension or heart failure symptoms. Key points to consider include:
- The size and location of the defect
- Associated valve abnormalities, such as mitral regurgitation
- Presence of other congenital heart defects, such as those associated with Down syndrome
- Potential for pulmonary hypertension and heart failure if left untreated
- Surgical repair as the primary management strategy, as recommended by the 2018 AHA/ACC guideline 1.
From the Research
Isolated Ostium Primum Defect
- The percentage of isolated ostium primum defect is not directly stated in the provided studies.
- However, study 2 mentions that ostium primum type atrial septal defects account for 2% of congenital heart disease cases diagnosed by catheterization and angiography.
- Study 3 reports on 56 children who underwent repair of incomplete endocardial cushion defects, with 40 patients having isolated ostium primum defects, which is approximately 71% of the total cases in that study.
- Study 4 focuses on the long-term follow-up after surgical repair of ostium primum atrial septal defects in adults, but does not provide a percentage of isolated cases.
- Study 5 discusses the risks associated with ostium primum defects in the context of flying and congenital heart disease, but does not provide a specific percentage of isolated cases.
- Study 6 is related to cleft mitral valve without ostium primum defect and does not provide information on the percentage of isolated ostium primum defects.