Adult Echocardiography Practice Exam

What Qp/Qs ratio indicates surgical repair for an atrial septal defect with right ventricular dilation?

1. Greater than 0.8:1

2. Greater than 1.5:1

3. Greater than 1.2:1

4. Equal to 1.0:1

The correct answer is: Greater than 1.5:1

In assessing patients with an atrial septal defect (ASD), the Qp/Qs ratio, which compares pulmonary blood flow (Qp) to systemic blood flow (Qs), is a crucial determinant for deciding whether surgical intervention is necessary. A Qp/Qs ratio greater than 1 indicates that more blood is flowing to the lungs than the systemic circulation, which can lead to volume overload of the right heart. When the Qp/Qs ratio is greater than 1.5:1, it is indicative of significant left-to-right shunting. This level of shunting can lead to complications such as right ventricular dilation and might suggest that the right heart is under excessive strain due to the extra volume it is receiving. Surgical repair of the ASD is often recommended in these cases to prevent long-term sequelae like pulmonary hypertension, right heart failure, and further cardiac remodeling. This threshold for surgical intervention is critical, as it helps to identify patients who are at risk for worsening symptoms or hemodynamic instability if the defect is left uncorrected. Thus, a Qp/Qs ratio greater than 1.5:1 serves as a clear indicator that surgical repair is warranted when right ventricular dilation is present.