Some symptoms of a weak heart include difficulty in breathing, general body weakness, irregular heartbeat, nausea, loss of appetite, impaired thinking and swelling in certain body parts. A weak heart normally leads to heart failure, which is a condition characterized by an inability of the heart to pump enough blood, according to the National Heart, Lung and Blood Institute.
When the heart is unable to pump enough blood, it usually leads to multiple complications because oxygen and other nutrients are not sufficiently supplied to other parts of the body. A person with a weak heart is likely to feel tired since the supply of blood is diverted to the brain, rendering body parts such as the hands and legs weak.
With little supply of blood flowing, the heart is forced to start pumping at a rapid rate in order to compensate for the dwindling levels. This may lead to irregular heartbeats.
The dwindling levels of blood make it equally difficult for the kidneys to function properly. This causes a nauseating feeling and may lead a patient to feeling full, causing him or her to lose his or her appetite.
Another symptom of a weak heart is confusion or poor thinking capacity, which is brought about due to lack of sufficient nutrients such as sodium, which is vital for proper brain function.