Shortness of breath when supine and leg edema are symptoms indicative of which condition?

Shortness of breath when supine, also known as orthopnea, and leg edema are classical symptoms of Congestive Heart Failure (CHF). In CHF, the heart is unable to pump blood effectively, which leads to fluid accumulation in the tissues—this manifests as leg edema. When a person with CHF lies flat, gravity changes the distribution of fluids in the body, causing increased pressure on the lungs and resulting in difficulty breathing, hence the shortness of breath. These symptoms combined indicate that the heart is struggling to maintain adequate circulation and manage the volume of blood returning from the lower extremities, making CHF the most appropriate diagnosis in this scenario.