What does orthopnea indicate in a patient?

Orthopnea refers to difficulty breathing when lying flat, which is often a sign of left-sided heart failure. In this condition, blood backs up into the pulmonary circulation when the patient lies down, leading to pulmonary congestion and increased pressure in the lungs. As a result, patients may experience shortness of breath, prompting them to sleep in an upright position or with several pillows to alleviate their symptoms.

This phenomenon is linked specifically to left-sided heart failure, where the left ventricle is unable to effectively pump blood out to the body, which can cause fluid to accumulate in the lungs. Although other conditions, such as right-sided heart failure and aspiration pneumonia, can cause breathing difficulties, they do not typically present with orthopnea in the same manner as left-sided heart failure does. Therefore, in the context of orthopnea, the most accurate choice is left-sided heart failure.