Pulmonary hypertension occurs in the blood vessels in the lungs and heart when the blood vessels are blocked or damaged. Excessive fat tissue can place too much pressure on the organs, often leading to blood vessel damage or narrowing. The hardening of these blood vessels can cause the heart or lungs to work harder, leading to the development of diseases, including pulmonary hypertension. There is no treatment for pulmonary hypertension, so it is important to do whatever is possible to prevent its development. Pulmonary hypertension is also notable as it is a common complication of Pickwickian syndrome when appropriate treatment is not undertaken or when the condition is particularly severe.