Pulmonary hypertension (PH) is an incurable and life-threatening disease characterized by high blood pressure in the lung arteries. The severe medical condition is diagnosed when the blood vessels responsible for transporting blood from the heart to the lungs become narrowed and obstructed, causing the heart to work harder to properly pump the blood. As a result, the heart becomes enlarged and weakened, which can result in right heart failure.
The symptoms associated with the disease include shortness of breath, tiredness, chest pain, irregular heartbeat, pain in the upper right side of the abdomen, and decreased appetite. Despite the fact that there is no cure for PH, there are treatments to help patients manage their symptoms and improve their quality of life. Symptoms, diagnosis, and treatment vary according to the different types of PH and pulmonary hypertension classification. The most commonly used classification for the disease is the one defined by the World Health Organization, which divides the disease into groups and classes.
How Is PH Classified?
The International Classification of Diseases (ICD) is determined by WHO and is the standard diagnosis tool in the medical field for epidemiology, health management, and clinical purposes. In order to establish the pulmonary hypertension classification, the organization evaluated the general health situation of PH patients, as well as disease incidence and prevalence.
Pulmonary hypertension classification is separated by the organization into five groups, organized according to the cause of the subtype of disease. This classification is used as a resource for physicians, nurses, other providers, researchers, health information managers and coders, health information technology workers, policymakers, insurers, and patient organizations.
It is used for numerous purposes, including records, death certificates, information storage, diagnosis retrieval, national mortality and morbidity statistics, reimbursement, resource allocation, and other clinical, epidemiological, and quality purposes.
In addition, there is also a pulmonary hypertension functional classification, which is separated into four different classes and is used to rate the sickness of patients. It is used to distinguish the class of each patient to evaluate the evolution and stage of the disease. The higher the class, the more severe the disease, but there can be reversals due to more intense or new treatments or the disappearance of external factors that influenced it.
Different Groups of Pulmonary Hypertension Classification
The first division is called Group 1 Pulmonary Arterial Hypertension, the only one classified as pulmonary arterial hypertension, while all the others refer to pulmonary hypertension. In all of the groups, the average pressure in the pulmonary arteries is 25 mmHg or more at rest, or 30 mmHg during physical activity; the normal levels are between 8 and 20 mmHg at rest.
Group 1 includes the cases where the cause is unknown (idiopathic), inherited disease, PAH caused by the use of drugs or medicines, as well as PAH caused by connective tissue diseases, HIV infection, liver disease, congenital heart disease, sickle cell disease, the parasite-related infection called schistosomiasis (SKIS-toe-so-MI-ah-sis), and conditions that affect the veins and small blood vessels of the lungs.
Group 2 Pulmonary Hypertension refers to the disease that affects the left side of the heart, such as mitral valve disease or long-term high blood pressure, and can result in left heart disease and PH. Group 3 Pulmonary Hypertension includes PH related to lung diseases, like chronic obstructive pulmonary disease (COPD) and interstitial lung diseases, which can cause scarring of the lung tissue, while Group 4 Pulmonary Hypertension refers to cases of the disease caused by blood clots in the lungs or blood clotting disorders.
The last division is Group 5, and includes PH related to numerous other medical conditions. The most common diseases in this list are blood disorders, such as polycythemia vera and essential thrombocythemia; and systemic disorders such as sarcoidosis and vasculitis. Systemic disorders involve many of the body’s organs, metabolic disorders, such as thyroid disease and glycogen storage disease, as well as other conditions, such as tumors that press on the pulmonary arteries and kidney disease.
Different Classes of Pulmonary Hypertension Classification
The pulmonary hypertension classification is focused on patients’ symptoms and is not linear. Patients may be diagnosed in an advanced class, since they aren’t receiving any treatment, but due to the medication end up moving to a lower class. The higher the class, the worse the symptoms experienced by the patient.
According to WHO, class I refers to patients who do not experience symptoms with exercise or at rest, and it is uncommon for patients to be diagnosed while in this class. A good response to proper treatment can help patients return to class I after being diagnosed in class II or III.
Class II identifies patients with no symptoms at rest but who feel uncomfortable and have shortness of breath with ordinary activities like climbing stairs, shopping for groceries, or making the bed.
Class III includes patients who experience no symptoms at rest but feel limited in normal activities due to shortness of breath, fatigue, or near fainting, while class IV refers to patients whose symptoms are present even at rest and are severe while doing any activity. Fainting is also common among patients in this last class, particularly while bending over with their heads lowered. Most patients also have edema in the feet and ankles as result of right heart failure.
The New York Health Association (NYHA) also has defined a similar classification by classes. According to this alternative denomination, patients in class 1 don’t experience any symptoms with ordinary physical activity, while in class 2, patients suffer symptoms while performing regular activities and experience a slight limitation of activity. In class 3, patients experience symptoms with less-than-normal activity, and have a marked limitation of activity, and in class 4, people suffer the symptoms of the disease with any activity or even at rest.
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