What is the most important factor for the spontaneous closure of a ventricular septal defect?

The most significant factor influencing the spontaneous closure of a ventricular septal defect (VSD) is indeed the size of the defect. Smaller VSDs are more likely to close spontaneously over time compared to larger ones. This is primarily due to the increased pressure difference across the defect in larger VSDs, which typically results in higher blood flow through the defect from the left ventricle to the right ventricle, leading to continued right ventricular overload and potential complications.

In contrast, smaller defects may allow for a more favorable hemodynamic environment that encourages tissue growth around the defect, facilitating closure. Studies show that defects less than 3 mm in diameter have a higher rate of spontaneous closure, while those larger than 5 mm are less likely to close on their own.

Other factors, such as the location of the defect, the patient's age, and the presence of symptoms, play a role in the overall management and prognosis of VSDs but are not as directly correlated with the likelihood of spontaneous closure as the size of the defect. For example, while older patients may have a different healing response and symptoms might indicate the need for intervention, these factors do not significantly alter the intrinsic likelihood of closure based on defect size.