Perspective:

The following are 10 points to remember regarding this systematic review of the definition and management of hemodynamically insignificant left-to-right shunts:

1. Examples of hemodynamically insignificant left-to-right shunts include small atrial septal defect (ASD) or patent foramen ovale (PFO), small ventricular septal defect (VSD), and small patent ductus arteriosus (PDA).

2. Although such minor lesions are relatively common, there are no clear guidelines or standardization for their management.

3. A recent study has demonstrated that patients referred to a tertiary center for murmur, innocent murmurs, PDA, VSD, and branch pulmonary stenosis in infancy accounted for 91% of diagnoses.

4. There is variability in the definition and diagnosis of small interatrial defects. Recent publications define ASDs as having a diameter >4 mm.

5. Atrial defects measuring <3 mm generally close or decrease in size, while approximately 80% of defects 3-6 mm in diameter close spontaneously. Defects >8 mm are unlikely to close spontaneously. For larger defects with diameters of 6-7 mm after 1 year of age, yearly follow-up is recommended until 4-5 years of age.

6. If older children with a diagnosis of PFO are discharged from the clinic, it is reasonable to include a discussion with the family regarding the implications of scuba diving.

7. Muscular VSDs close in 80% of cases early in life.

8. There is wide variation in the reported prevalence of the long-term complications of small VSDs, with endocarditis estimated at 1.8-15%, aortic regurgitation at 2-10%, and arrhythmias at up to 10% of patients.

9. The estimated endocarditis risk for silent PDAs ranges from 0.001% to 0.01% per year. This very small risk of endocarditis should be weighed against the risk of complications associated with closure procedures.

10. A recurring theme in the follow-up and management of small left-to-right shunt lesions is significant practice-pattern variations between individual practitioners as well as between different centers. Consensus opinions for the management and follow-up of such lesions are needed to reduce parental anxiety, as well as unnecessary testing and procedures.