1. Narrowing of blood vessels - heart has to work harder to ensure adequate blood flow.
2. Valves (commonly the left) are damaged - some backflow is occurring.
3. Weakening of the heart muscle - decreased amount of blood flowing to vital organs.
4. Enlarged heart - can compress wind pipe and cause coughing.
5. Kidneys detect a decrease in blood flow - retain more fluid.
6. Fluid retention by kidneys can cause fluid to leak into the lungs - leads to coughing and difficulty breathing.