What is Pulmonary Hypertension?
Pulmonary hypertension is a rare blood vessel disorder of the lung in which the pressure in the pulmonary artery (the blood vessel that leads from the heart to the lungs) rises above normal levels and may become life threatening.
Symptoms of pulmonary hypertension include shortness of breath with minimal exertion, fatigue, chest pain, dizzy spells and fainting.
Idiopathic Pulmonary Hypertension
When pulmonary hypertension occurs in the absence of a known cause, it is referred to as idiopathic pulmonary arterial hypertension (IPAH). This term should not be construed to mean that because it has a single name it is a single disease. There are likely many unknown causes of IPAH. IPAH is extremely rare, occurring in about two persons per million population per year.
Secondary Pulmonary Hypertension
Secondary pulmonary hypertension means the cause is known. A common cause of secondary PH are the breathing disorders emphysema and bronchitis. Other less frequent causes are the inflammatory or collagen vascular diseases such as scleroderma, CREST syndrome or systemic lupus erythematosus (SLE). Congenital heart diseases that cause shunting of extra blood through the lungs like ventricular and atrial septal defects, chronic pulmonary thromboembolism (old blood clots in the pulmonary artery), HIV infection, liver disease and diet drugs like fenfluramine and dexfenfluramine are also causes of pulmonary hypertension.
Categories of PH
In 2003, the World Health Organization (WHO)* sponsored a meeting of PH specialists with the goal of revising a standardized system for defining different kinds of PH, which had been created at a previous WHO sponsored meeting five years earlier. The committee proposed that the disease be divided into the following five categories of pulmonary hypertension:
1. Pulmonary arterial hypertension (PAH)
The pulmonary arteries are the vessels that carry blood from the heart into the lungs so it can pick up oxygen. PAH affects the millions of tiny blood vessels that branch off from the larger pulmonary artery that is connected
to the heart.
This category includes:
-Idiopathic PAH (IPAH, formerly primary pulmonary hypertension) occurs without any apparent cause.
-Familial PAH is an inherited disease identical to IPAH. It is estimated that approximately 10 percent of cases of PAH occur in families where at least one other person has had the disease.
Associated with PAH (APAH) appears to be similar to IPAH, but is actually associated with exposure to toxins, or the effects of other diseases. These can include:
-Collagen vascular disease (scleroderma and lupus primarily)
-Congenital heart disease
-Chronic liver disease
-Human immunodeficiency virus (HIV)
-Sickle cell disease
-Use of diet drugs such as fenfluramine or dexfenfluramine
-Use of cocaine, methamphetamine, or other street drugs
-Persistent pulmonary hypertension of the newborn
-Other (hemorrhagic hereditary telangectasias, glycogen
storage disease, etc.)
Associated with significant venous or capillary involvement: pulmonary venooclussive disease, pulmonary capillary hemangiomatosis, respectively.
2. Pulmonary venous hypertension (PVH)
PVH is caused by diseases of the left side of the heart, such as mitral valve disease or a poorly performing left ventricle. This can cause increased pulmonary artery pressures that can be severe in some cases and difficult to differentiate from PAH.
3. Pulmonary hypertension associated with disorders of the respiratory system and/or hypoxia
-Chronic obstructive lung disease
-Interstitial lung disease
-Sleep disordered breathing
-Alveolar hypoventilation disorders
-Chronic exposure to high altitude
4. Pulmonary hypertension due to chronic thrombotic and/or embolic disease
-Thromboembolic obstruction of proximal pulmonary arteries
-Thromboembolic obstruction of distal pulmonary arteries
-Non-thrombotic pulmonary emobolism (tumor, parasites, foreign material)
-Compression of pulmonary vessels (adenopathy, tumor, fibrosing mediastinitis)
PH is often not diagnosed in a timely manner because its early symptoms can be confused with those of many other conditions. Some of the symptoms of PH include:
-Breathlessness or shortness of breath, especially with activity
-Feeling tired all the time
-Lightheadedness, especially when climbing stairs or upon standing up
-Swollen ankles, legs, or abdomen
-Chest pain, especially during physical activity
To establish a diagnosis of PH, a series of tests are performed that show how well a person’s heart and lungs are working. These tests may include:
-Echocardiogram (ultrasound of the heart)
-Electrocardiogram (ECG, a recording of the electrical current in the heart)
-Right heart catheterization (direct measurement of pressure in the pulmonary arteries and determination of how well the heart is pumping blood to the body)
-Six-minute walk test to assess exercise capacity
If these tests show that a person definitely has PH, other kinds of diagnostic tests may be ordered to aid in identifying the cause, including:
-Ventilation-perfusion (V/Q) scan to rule out a pulmonary embolism (blood clot in pulmonary arteries)
-A computed tomography (CT or CAT) scan to rule out abnormalities of the lung tissue and to assess for a pulmonary embolism
-A pulmonary function test to rule out disease in the lung tissue such as emphysema or pulmonary fibrosis
-A formal sleep study to rule out sleep apnea
-Laboratory tests to rule out hepatitis, collagen disease, HIV, or other conditions
-When no cause can be found, the diagnosis is idiopathic PAH.