What is a symptom of left heart failure?

In the context of left heart failure, the primary issue is the heart's inability to effectively pump blood out to the body. This results in a buildup of pressure within the left atrium and subsequently in the pulmonary circulation, leading to fluid accumulation in the lungs. This condition is known as pulmonary congestion or pulmonary edema, which is characterized by symptoms such as dyspnea (shortness of breath) and orthopnea (difficulty breathing when lying flat).

When blood backs up into the lungs due to left heart failure, it can cause significant respiratory issues since the excess fluid interferes with normal gas exchange in the alveoli. This is a key reason why understanding left heart failure involves recognizing the compromised function of the heart and how it affects the pulmonary system.

The other options, while they may relate to other conditions or types of heart failure, do not specifically illustrate the direct consequence of left heart failure as clearly as the backup of blood into the lungs does.