How are congenital heart defects (CHDs) primarily classified?

Congenital heart defects (CHDs) are primarily classified by pulmonary blood flow characteristics. This classification focuses on how the heart's structural anomalies affect the flow of blood through the pulmonary and systemic circulation, which is critical for determining the clinical management and treatment options for each defect.

Within this framework, defects are typically categorized into two main types: those that increase pulmonary blood flow, leading to conditions such as atrial septal defects or ventricular septal defects, and those that decrease pulmonary blood flow, commonly seen in conditions like tetralogy of Fallot or pulmonary atresia.

Understanding the characteristics of pulmonary blood flow is essential because it directly impacts the clinical presentation, potential symptoms, and the urgency of intervention required for the patient. This classification helps healthcare providers develop appropriate treatment strategies and predict long-term outcomes for children with CHDs. Other classification methods, such as severity and symptoms, may take into account additional aspects but do not serve as the primary basis for understanding the physiological impact of the defects.