MEDICAL ANIMATION TRANSCRIPT: In the normal heart, deoxygenated blood flows from the body through the superior and inferior vena cava into the right atrium. The blood, a volume known as preload, then moves into the right ventricle, which contracts and sends blood out of the heart and into the lungs to remove carbon dioxide and collect oxygen. Oxygenated blood moves from the lungs into the left atrium, then moves into the left ventricle which contracts and propels oxygenated blood out of the heart and into the systemic circulation against resistance known as after load. When the heart losses its ability to pump enough blood to meet its needs or those of the body, the diagnosis is heart failure. In left-sided heart failure, the left ventricle does not pump an adequate volume of oxygenated blood into the systemic circulation. Left-sided heart failure causes pulmonary congestion, a buildup of blood and fluid in the lung tissues that interferes with respiration. In response to the low leve...