What are the Kerley B lines indicative of in a chest X-ray?

Kerley B lines are specific radiographic findings seen on a chest X-ray that indicate the presence of interstitial edema, which is commonly associated with pulmonary edema. These lines appear as thin, horizontal lines at the lung periphery, typically found in the lower zones of the lungs. They represent thickening of the interlobular septa due to fluid accumulation, which occurs when left-sided heart failure leads to increased pulmonary venous pressure and, subsequently, transudation of fluid into the lung interstitium.

In the context of heart failure or conditions that cause fluid overload, pulmonary edema results in these characteristic lines being visible. They serve as an important diagnostic clue in clinical practice for practitioners evaluating patients with respiratory distress or signs of heart failure. Understanding the significance of Kerley B lines can directly influence the management and treatment decisions for patients presenting with these conditions.