What is Secondary Pulmonary Hypertension Caused By?
Pulmonary hypertension (PH) also known as pulmonary arterial hypertension (PAH) is a serious progressive disease, in which there is elevated blood pressure in the arteries supplying the lungs. The blood flow from the heart to the lungs is disrupted due to constriction in blood vessels causing elevated pulmonary arterial pressure. Normal pressures in pulmonary arteries include 15-30 mm Hg systolic pressure and 4-12 mm Hg diastolic pressure. If the pressure is greater than 30/12 mm Hg, then it is known as pulmonary hypertension.
What is Secondary Pulmonary Hypertension Caused By?
Pulmonary hypertension can be caused due to unknown reasons, known as primary pulmonary hypertension. When pulmonary hypertension is caused secondary to some other diseases then it is known as secondary pulmonary hypertension.
The different causes of secondary pulmonary hypertension include autoimmune diseases such as rheumatoid arthritis and SLE, connective tissue diseases (scleroderma, CREST syndrome, lupus), liver diseases, congenital heart diseases (atrial and ventricular septal defects), sickle cell anemia, HIV infection and schistosomiasis (parasitic infection). It can also be caused due to drugs and certain toxins including some of diet pills (such as fenfluramine and dexfenfluramine) and recreational drugs. It can also be caused by various breathing and lung conditions such as chronic obstructive pulmonary disease (COPD), emphysema, pulmonary fibrosis (interstitial lung diseases) and sleep apnea. In addition, it can also be caused by clotting disorders such as blood clots in the lungs (pulmonary emboli) along with diseases affecting small blood vessels in the lungs.
Heart failure and other conditions affecting left side of the heart including mitral valve disease and chronic systemic elevated blood pressure can also cause secondary PH. In addition, causes of secondary PH include blood disorders (polycythemia vera and thrombocythemia), metabolic disorders such as thyroid diseases and glycogen storage disease, systemic disorders (such as sarcoidosis and vasculitis), kidney diseases and other conditions including tumors causing compression of pulmonary arteries.
Pulmonary hypertension is more prevalent in females than in males around the age group of 30 to 40.
Symptoms of Secondary Pulmonary Hypertension
The symptoms of secondary pulmonary hypertension arise due to increased pressure in the pulmonary arteries, leading to constriction of the blood vessels. This in turn creates excess stress to heart muscles ultimately leading to weakness of heart muscles with time. The common symptoms of secondary pulmonary hypertension are fatigue, difficulty breathing and dizziness. Other symptoms include rapid breathing, exertional shortness of breath (dyspnea), chest pain, anxiety, lower extremity swelling, tachycardia, distention of jugular vein, ascites (fluid collection in the abdomen), and clubbing of fingers. In addition, severe secondary pulmonary hypertension may also lead to heart failure.
Diagnosis and Treatment of Secondary Pulmonary Hypertension
The diagnosis of pulmonary hypertension is difficult to make as the symptoms of pulmonary hypertension often overlap those of other heart and lung diseases. Therefore, it is not diagnosed until it becomes very severe. In addition to blood tests, certain imaging tests are also done including right heart catheterization, echocardiogram (heart ultrasound), pulmonary function tests, chest X-ray, computed tomography, electrocardiogram, stress test and nuclear medicine lung scan. The treatment plan is based on the results of these tests as these tests also help in finding out the cause of disease.
Unfortunately, there is no definitive treatment/cure for pulmonary hypertension. The aim of the treatment is focused on slowing/delaying the progress of the disease by improving the quality of life of the patient with medications to lower blood pressure, thinning of blood, helping heart to pump more efficiently, opening up constricted blood vessels and removing excess fluid from the body. This is achieved by treating underlying cause with the help of blood thinners, diuretics, lowering blood pressure and dilatation of blood vessels. On occasions, the patient might also require oxygen supplementation in cases of difficulty in breathing.
The prognosis of patients with pulmonary hypertension is generally poor, but with the advent of new medications and more research and studies, there seems to be a hope for greater life expectancy in the people suffering from this life-threatening disease.
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