Chronic obstructive pulmonary disease will increase the resistance of the pulmonary circulation, resulting in pulmonary hypertension, the right heart to play a compensatory function at the same time there are functional and structural changes, i.e., chronic pulmonary heart disease. Long-term, repeated episodes of chronic obstructive pulmonary disease will involve the surrounding small pulmonary arteries, resulting in vasculitis, vascular wall fibrosis, thickening, lumen narrowing or even occlusion will lead to increased pulmonary vascular resistance. Chronic hypoxia caused by COPD also leads to an increase in leukotrienes and other vasoconstrictor active substances causing pulmonary vasoconstriction and increased resistance. Increased pulmonary vascular resistance as well as increased blood viscosity and increased blood volume due to hypoxia secondary to erythropoiesis all work together to create pulmonary hypertension. The increase in pulmonary artery pressure and the compensatory role of the right ventricle in overcoming pulmonary artery resistance are accompanied by hypertrophy of the right ventricle. Early right ventricular function is compensated for, but when the disease progresses, right heart failure may lead to enlargement of the right ventricle or even right heart failure. Functional and/or structural changes in the right heart secondary to lung disease are known as pulmonary heart disease. Therefore, it is recommended that people with chronic lung disease seek prompt medical attention and active intervention to avoid the development of pulmonary heart disease.