The symptoms of heart failure are related to the changes that occur to your heart and body, and may be moderate to severe, depending on how weak your heart is. The symptoms can include:

• Congested lungs. Fluid back-up in the lungs can cause shortness of breath with exercise, or difficulty breathing at rest or when lying flat in bed. Lung congestion also causes a dry, hacking cough or wheezing.
• Fluid and water retention. Less blood to your kidneys causes fluid and water retention, resulting in swollen ankles, legs and abdomen (called oedema) and weight gain. Symptoms may cause an increased need to urinate during the night. Bloating in your stomach may cause a loss of appetite or nausea.
• Dizziness, fatigue and weakness. Less blood to your major organs and muscles makes you feel tired and weak. Less blood to the brain can cause dizziness or confusion.
• Rapid or irregular heartbeats. The heart beats faster to pump enough blood to the body. This causes a fast or irregular heartbeat.