Ace the PCCN Exam 2026 – Elevate Your Progressive Care Nursing Game!

An atrial septal defect (ASD) is primarily characterized by blood flow that involves a left-to-right shunt, which occurs when blood from the left atrium flows across the defect into the right atrium. This typically happens due to the higher pressure in the left atrium compared to the right atrium during diastole.

In this situation, blood returning from the lungs to the left atrium enters the left atrium, and because of the ASD, a portion of that blood is diverted into the right atrium rather than continuing into the left ventricle. This abnormal blood flow is a hallmark of ASDs, as it leads to increased blood volume in the right atrium, which can subsequently affect the right ventricle and pulmonary circulation but does not primarily reflect right ventricular hypertrophy or increased pulmonary pressure directly.

The other options describe consequences of an ASD rather than its fundamental blood flow characteristic. A left-to-right shunt can eventually lead to increased pulmonary pressure and potentially right ventricular hypertrophy due to volume overload, but these are downstream effects rather than defining features of the condition itself. Similarly, ventricular wall hypertrophy typically occurs in response to pressure overload rather than the flow characteristics of an ASD.