According to WHO, there are five types of pulmonary hypertension ranging from type 1 to type 5. Type 1 relates to numerous causes including connective tissue diseases (autoimmune diseases), liver diseases, congenital heart diseases, HIV infection, schistosomiasis (parasitic infection), due to drugs (include some of diet pills and recreational drugs). This group also includes idiopathic and genetic cause. Type 2 PH is caused by conditions affecting left side of the heart including mitral valve disease and chronic systemic elevated blood pressure. Type 3 PH is related to various lung conditions such as chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (interstitial lung diseases), and sleep apnea. Type 4 PH is associated with clotting disorders such as pulmonary emboli. Type 5 PH includes blood disorders (polycythemia vera and thrombocythemia), metabolic disorders including thyroid diseases and glycogen storage disease, systemic disorders (such as sarcoidosis and vasculitis), sickle cell disease, kidney diseases and other conditions including tumors causing compression of pulmonary arteries.
Pulmonary Hypertension Treatment Guidelines
The updated 2015 European Society of Cardiology/European Respiratory Society guidelines for pulmonary hypertension treatment include the following:
Pulmonary hypertension is considered a pathophysiological disease, which involves one or more other diseases and can worsen other respiratory and cardiovascular diseases. PH is a state of increased pulmonary artery pressure, greater than 25 mm Hg, in pulmonary artery when measured by right heart catheterization. The normal pulmonary artery pressure should be less than 20 mm Hg. People who have pulmonary artery pressure in 21-24 mm Hg range have a greater risk of developing PH.
There is confusion in classification of PH that may lead to overtreatment of patients. Pulmonary arterial hypertension (PAH) is just a subgroup (type 1) of PH with precapillary PH. Post capillary PH is related to left heart and valve disease. It is interesting to note that about 50% cases of PAH are either idiopathic, hereditary or drug induced.
Transthoracic echo is used as an initial screening/diagnostic approach, but for treatment, right heart catheterization is necessary. VQ scan is the preferred scan for screening of chronic catheterization PH. Cardiac MRI is preferred when checking morphology, function and mass in right ventricle of heart and is useful in prognosis and treatment of congestive heart failure. It should be noted that in patients with non-idiopathic PAH, right heart failure and/or low cardiac output; calcium channel blockers should be used cautiously as they might cause vasoreactivity.
General treatment principles include proper diagnosis of the patient and classifying them according to WHO classification and treating them according to that. PAH should be differentiated with other PH and right heart catheterization should be performed for confirmation. Treatment measures also include lifestyle modification with weight control, staying active with physical activity, pulmonary rehabilitation. Women should prevent pregnancy and should be on combination therapy of birth control pills along with PAH specific treatment. These patients should get psychological and social support, they should be up-to-date on various vaccines such as seasonal flu and pneumonia.
The patients suffering from PH are deficient in iron and are usually anemic, so they should take iron supplements and should be treated for anemia. Patients who have less severe form of PH can be treated with oral medications, but combination therapy of oral and inhaled medications should be considered in patients who are on monotherapy and still have persistence of symptoms. Severe forms of PH and rapidly progressing PH in patients on oral/inhalers should be treated with IV and/or subcutaneous drugs such as Flolan, Tyvaso and Remodulin.
Oral anticoagulant therapy should be started in heritable and idiopathic PAH. If patients are hypoxemic, they should be given oxygen therapy. PH patients should be prescribed diuretics for reduction of right ventricular failure symptoms. In conjunction to PH specialist, other specialists should also be consulted in cases of pregnancy, elective/urgent/emergency surgery in PH patients. Patients suspected for PAH should be referred to PH specialist for confirmation of diagnosis before initiation of treatment and should follow up with them regularly to monitor response, subsequent therapy decisions such as lung transplant consideration and referral.
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