Pulmonary hypertension is high blood pressure in the arteries to your lungs. It is a serious condition for which there are treatments but no cure. If you have it, the blood vessels that carry oxygen-poor blood from your heart to your lungs become hard and narrow. Your heart has to work harder to pump the blood through. Over time, your heart weakens and cannot do its job and you can develop heart failure.
There are two main kinds of pulmonary hypertension. One runs in families or appears for no known reason. The other kind is related to another condition, usually heart or lung disease.
Treating pulmonary hypertension involves treating the heart or lung disease, medicines, oxygen and sometimes lung transplantation.
CLASSIFICATION OF PH
In the conventional classification, pulmonary hypertension, which is also called pulmonary arterial hypertension, is divided into two main categories; 1) primary pulmonary hypertension (not caused by any other disease or condition); and 2) secondary pulmonary hypertension (caused by another underlying condition). Secondary pulmonary hypertension is much more common than primary pulmonary hypertension.
A newer classification of this condition is based on the main underlying cause of pulmonary hypertension. This system classifies the condition based on whether it is due to:
- left sided heart disease,
- lung disease,
- blood clots,
- constriction of arteries due to any reasons (including primary pulmonary hypertension), and
- obstruction from outside of blood vessel (for example from diseases of the chest wall compressing the blood vessels).
CAUSES OF PH?
Pulmonary hypertension can be caused by diseases of the heart and the lungs, such as:
- chronic obstructive pulmonary disease (COPD)
- emphysema,
- failure of the left heart ventricle,
- recurrent pulmonary embolism (blood clots traveling from the legs or pelvic veins obstructing the pulmonary arteries or chronic thromboembolic pulmonary hypertension), or
- underlying diseases such as scleroderma.
- dermatomyositis,
- systemic lupus erythematosus,
- sarcoidosis,
- human immunodeficiency virus (HIV), and
- advanced liver disease (porto-pulmonary hypertension). sleep apnea or other long-standing (chronic) lung disease.
Again, pulmonary hypertension caused by these other illnesses can also be referred to as secondary pulmonary hypertension.
When pulmonary hypertension occurs without underlying heart and lung disease or other illnesses, it is called primary pulmonary hypertension. Primary pulmonary hypertension is more common in younger people and more in females than in males.
Recently this condition has been rarely reported with the use of anti-obesity drugs such as dexfenfluramine (Redux) and Fen/Phen. These medications have seen been removed from the market. Some street drugs such as, cocaine and methamphetamines can cause severe pulmonary hypertension
Many people with pulmonary hypertension may have no symptoms at all, especially if the disease is mild or in early stages.
Pulmonary hypertension symptoms may include:
- The most common symptoms of pulmonary hypertension is shortness of breath that worsens with activity.
- Other common complaints are cough, fatigue, dizziness, and lethargy.
- With the advancement of the condition and ensuing right heart failure, shortness of breath may get worse and retention of fluid in the body may increase (due to failure of the heart to pump blood forward) resulting in swelling the legs.
- People may also complain of chest pain and angina.
- A rapid breathing, hypoxia (low oxygen level in the blood), and swelling in the legs.
- In severe pulmonary hypertension, the doctor may hear louder than normal components of heart sounds when he or she listens to the heart with a stethoscope (auscultation).
- The doctor may also feel elevation of the chest wall when the heart pumps and this may indicate enlargement of the right side of the heart suggestive of pulmonary hypertension (right ventricular heave).
DIAGNOSIS OF PH?
The first step in diagnosis of pulmonary hypertension is to clinically suspect it. This may be done as part of an evaluation of another disease that can lead to pulmonary hypertension (such as scleroderma or chronic obstructive pulmonary disease) or based on patients and signs and symptoms as described above.
Many tests, such as echocardiogram, may be performed that be give us clues to the possibility of pulmonary hypertension. But the gold standard (the best test available) is right heart catheterization. This test entails inserting a catheter through the groin into the femoral vein, a large vein in the lower body (or under the collar bone or in the upper arm into the subclavian vein, a large vein in the upper body) and advancing it to the right side of the heart. The catheter is connected to a device that can monitor and measure blood pressure in the right side of the heart and pulmonary arteries.
During right heart catheterization, response to certain medication to treat pulmonary hypertension can be assessed. This is done by administering medications for pulmonary hypertension while the patients still has the catheter placed in heart. Then pulmonary blood pressure is monitored and the response to treatment is compared to no treatment. This can give the physicians a clue as to if an individual is a candidate for a certain therapy and also what dosage of the medicine may be appropriate.
Pulmonary hypertension is defined as the mean pulmonary artery blood pressure greater than 25 millimeter of mercury (mmHg) measured by right heart catheterization. The pressures can be much higher than 25 mmHg in some people. Therefore, the pulmonary hypertension can be labeled as mild, moderate, or severe based on the pressures. Mean arterial pressure is two-thirds of the difference between systolic and diastolic blood pressure (systolic is the upper number and diastolic is the lower number in measuring blood pressure). As explained above, the pulmonary blood pressure is much lower than the systemic blood pressure.
Other tests available for diagnosing pulmonary hypertension include electrocardiogram (ECG), chest x-ray, and echocardiogram. An ECG may show some abnormalities that may be suggestive of right heart failure. Chest x-ray may also show enlargement of the chambers of the right heart. And echocardiogram (ultrasound of the heart) shows ultrasound images of the heart and can detect evidence of right heart failure and pressures in the pulmonary artery can be estimated. These tests, in the right clinical setting, are very useful in diagnosing pulmonary hypertension.
Other tests may be useful in evaluating the conditions leading to secondary pulmonary hypertension. For example, a ventilation-perfusion scan (V/Q scan) can detect blood clots in the pulmonary arteries suggesting chronic thromboembolic pulmonary hypertension. A pulmonary function test can be useful in diagnosing chronic obstructive pulmonary disease (COPD)
TREATMENT
The treatment for pulmonary hypertension depends on the underlying cause.
If left sided heart failure is the primary problem, then adequate treatment of the left heart failure by a cardiologist is the main stray of treatment.
In cases where hypoxia (low oxygen levels) due to any chronic lung disease, such as COPD, is the cause, then providing oxygen and appropriately treating the underlying lung disease by a lung doctor (pulmonologist) is the first step in treatment.
In conditions, such as scleroderma, which often can cause pulmonary hypertension, a rheumatologist is involved in the treatment program.
Anticoagulation (thinning the blood) may be a treatment option if the main underlying cause is thought to be recurrent blood clot (chronic thromboembolic pulmonary hypertension). As indicated , possible surgical removal of blood clot (thromboendarterectomy) would be also an option.
For patients with primary pulmonary hypertension (those with no underlying cause), more advanced therapy may be attempted. These drugs have complex mechanisms, but in general they work by dilating (opening up) the pulmonary arteries and, therefore, by reducing the pressure in these blood vessels.
Some of the most commonly used drugs prescribed to treat pulmonary hypertension include:
- epoprostenol (Flolan),
- bosentan (Tracleer),
- intravenous treprostinil (Remodulin),
- inhaled iloprost (Ventavis),
- sildenafil (Viagra, Revatio),
- calcium channel blockers (such as nifedipine),
- sitaxsentan (Thelin) - not FDA approved in the U.S., and
- ambrisentan (Letairis).
It is worth mentioning that regardless of the cause of pulmonary hypertension, supplemental oxygen and diuretics (water pills) may play an important role in relieving the symptoms of pulmonary hypertension of any cause. Therefore, they may be prescribed by the physician treating pulmonary hypertension.
Low oxygen in the atmosphere causes low blood oxygen levels and aggravates pulmonary hypertension. Therefore, patients with pulmonary hypertension may benefit from breathing supplemental oxygen, especially during air travel or traveling to high altitude destinations.
Despite advances in various treatments, there is no cure for pulmonary hypertension.
PROGNOSIS
Generally, the prognosis of pulmonary varies depending on the underlying condition that is causing it. For primary pulmonary hypertension, the overall prognosis depends on the severity and whether treatment was instituted. The statistics show a survival of about 3 years in primary pulmonary hypertension without any therapy. Some of the other factors may indicate even poorer prognosis which include severe symptoms, age of onset greater than 45 years, evidence of right sided heart failure, and failure to respond to treatment. For patients with primary pulmonary hypertension who get started on treatment and respond to it, the prognosis is better. Studies are underway to determine optimal treatment regimens
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