Among the symptoms of congestive heart failure is fluid retention, which is manifested by swelling of the feet, ankles, stomach, and lumbar areas (back). 
The increased volume of fluids further worsen cardiac function; deficiency in organ irrigation is also reflected in the kidney. Thus, we have a drop in kidney function, which filters less and less body fluid content, consequently, worsening fluid retention even more. When insufficient blood “feeds” the kidneys, its function deteriorates, leading to the accumulation of fluids. Due to this permanent tendency for sodium (salt) and water retention, it is a common medical recommendation for patients with heart failure to follow a strict diet such as low sodium diet (with a little salt) and with restricted fluid intake. 
Generally, the diet rule for congestive heart failure involves avoiding and limiting food intake according to the following:
Reducing Sodium Intake
Your body is continuously trying to establish a balance between different electrolytes. When you take in a large amount of sodium containing foods, your body tries to retain extra water to maintain it. For many individuals, this only results in little bloating and some discomfort. 
Conversely, people that have congestive heart failure already have excess fluids retained in their bodies, making extra fluid retention a more severe health problem. Medical professionals often recommend that people with CHF restrict their daily sodium intake to approximately 2,000 milligrams (mg). It’s a little less than 1 teaspoon of table salt. Although this amount of salt may seem like a hard amount to limit oneself to, there are a lot of other alternatives that can take to remove extra salt from your diet without having to sacrifice flavor.