The kidneys try to compensate for heart failure by retaining salt and water, thereby increasing circulating blood volume. However, the kidneys, particularly when they are diseased or not functioning properly, also produce hormones that maintain kidney blood flow even when the output from the heart is reduced. This means the kidneys may continue to retain salt and water even when blood volume has increased, causing further fluid accumulation and congestion. This may develop into a vicious cycle and aggravate heart failure.

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