As a result of acutely reduced pumping capacity of the left ventricle, the blood backs up into the pulmonary veins and thus into the pulmonary capillaries. The right ventricle pumps blood into the pulmonary circulation with increased force against this congestion. This forces fluid out of the pulmonary vessels into the lung tissue and into the alveoli. This fluid restricts the gas exchange between air and blood, and the affected patients suffer from (life-threatening) shortness of breath. Typical symptoms are rattling breathing, foamy sputum and cyanosis.
