Why would people with heart problems often have trouble breathing?

People with heart problems often experience trouble breathing due to the heart's diminished ability to pump blood effectively. This can lead to fluid buildup in the lungs, a condition known as pulmonary congestion, making it difficult to breathe. Additionally, reduced blood flow can cause the body to receive less oxygen, further exacerbating breathing difficulties. These issues can manifest as shortness of breath, especially during physical activity or when lying down.