Final answer:
Heart failure occurs when the heart is unable to pump adequate amounts of blood to the tissues and organs, resulting in a lack of oxygen to vital organs.
Step-by-step explanation:
Heart failure is the condition in which the heart is unable to pump adequate amounts of blood to the tissues and organs. It occurs when the pumping action of the heart is impaired, resulting in a lack of oxygenated blood reaching the vital organs. Without proper treatment, heart failure can lead to organ failure.