Pulmonary Hypertension

Symptoms of high blood pressure may be present in those who have extremely high blood pressure.

• Pulmonary arteries are the blood vessels that move blood from the right side of the heart to the lungs where oxygen is received into the blood. The oxygenated blood (blood that carries oxygen) is then transported back to the left side of the heart via the pulmonary veins.
• The pressure of blood circulating in the pulmonary arteries (pulmonary blood pressure) is normally significantly lower than the systemic blood pressure (pressure of blood measured routinely which is coming out the left side of the heart).
• Normal systemic systolic blood pressure is typically below 120 mmHg. In the pulmonary system, the blood pressure is typically 20 to 25 mmHg.
• If the pressure in the pulmonary arteries abnormally rises for any reason, the condition is referred to as pulmonary hypertension, pulmonary artery hypertension, or pulmonary arterial hypertension. In general, this rise in pressure is caused by tightening or constriction of the blood vessels carrying the blood to the lungs.
• This constriction hinders the flow of blood in the vessels, causing the blood to travel with a higher force and through a higher resistance, leading to high blood pressure.
• If left untreated, pulmonary hypertension can lead to right heart failure and death.
• There is no certain data on the statistics and prevalence of pulmonary hypertension because the condition is typically associated with other underlying diseases that are more readily diagnosed and treated.

Traditionally, pulmonary hypertension is divided into two classes: primary and secondary.

Primary pulmonary hypertension (or idiopathic pulmonary hypertension) is not caused by any other underlying condition.

Secondary pulmonary hypertension is caused by other underlying conditions, such as:

• recurring blood clots in the lungs,
• left-sided congestive heart failure,
• long-standing (chronic) lung diseases,
• illicit drug use,
• certain medications,
• some rheumatologic conditions, or
• inflammation of the pulmonary blood vessels.

More specifically, pulmonary hypertension may be caused by:

• chronic (long-standing) lung disease, such as emphysema or chronic bronchitis (also known as chronic obstructive pulmonary disease or COPD), obstructive sleep apnea, cystic fibrosis, or other chronic lung diseases.
• congestive heart failure.
• recurrent blood clot formation in the pulmonary arteries or blood clots traveling from the legs to the pulmonary arteries may result in pulmonary hypertension (chronic thromboembolic pulmonary hypertension).
• some rheumatologic conditions, such as scleroderma (systemic sclerosis), rheumatoid arthritis, or lupus.

Other less common causes of secondary hypertension include:

• illicit drugs (cocaine, speed, methamphetamine),
• some weight loss medications (Fen-Phen),
• HIV/AIDS,
• hyperthyroidism, and
• advanced liver disease.
• obstructive sleep apnea

Secondary pulmonary hypertension is much more common than primary pulmonary hypertension.

There is also a newer classification of this condition, which is more complex. In this system, pulmonary hypertension may be divided into five basic groups based on whether the underlying cause is:

1. lung disease,
2. heart disease,
3. vascular (blood vessel) disease,
4. blood clots, or
5. compression on the blood vessels from outside the vessel.

Because there are many conditions that can lead to pulmonary hypertension (as listed above), the risk factors for these conditions may also be considered risk factors for pulmonary hypertension. Therefore, the list of the risk factors for pulmonary hypertension may be very extensive.

Primary pulmonary hypertension (or idiopathic pulmonary hypertension) is largely sporadic, but it may be associated with a genetic mutation. A minority of these cases is seen in families (familial), and these may also be linked to a genetic predisposition.

Many patients with pulmonary hypertension may not have any symptoms at all (asymptomatic), especially if the condition is mild. Otherwise, the most common symptom of pulmonary hypertension is shortness of breath. Activity or exertion may provoke shortness of breath or make it worse.

Other less common symptoms may include:

• cough,
• fatigue,
• lethargy, and
• dizziness.

With the progression of the disease, right-sided heart failure (cor pulmonale) may ensue, resulting in:

• worsening of shortness of breath,
• fluid retention (edema) with swelling of the legs,
• chest pain, and
• angina.

Signs of pulmonary hypertension include:

• low oxygen level (hypoxia),
• rapid breathing,
• leg swelling, and
• signs associated with the underlying condition leading to pulmonary hypertension.

Pulmonary hypertension may go undetected and undiagnosed for some time. However, once the diagnosis is made, close monitoring is usually necessary and advisable. Patients with pulmonary hypertension are generally cared for by lung doctors (pulmonologists) and heart doctors (cardiologists).

The diagnosis of pulmonary hypertension requires clinical suspicion based on the signs and symptoms as described above, a detailed medical history and physical examination, and an evaluation of other conditions that may lead to pulmonary hypertension.

The best available test (gold standard) for diagnosing pulmonary hypertension is a right heart catheterization and measurement of blood pressure in the pulmonary arteries.

• In this test, a catheter is inserted into the right side of the heart via one of the large surface veins (femoral vein in the groin or subclavian vein under the clavicle).
• The catheter is connected to a pressure monitor and can measure the pressure in the right side of the heart and the pulmonary blood vessels.
• This is an invasive test and is usually done in specialized centers or university hospitals by highly trained physicians.
• Pulmonary hypertension is diagnosed if the pressure in the right heart catheterization is greater than 25mmHg. Depending on how high the pressure is, the condition may be classified as mild, moderate, or severe pulmonary hypertension.

Another less invasive method to measure pulmonary artery pressure is an echocardiogram (an ultrasound of the heart). An echocardiogram can estimate the blood pressure in the pulmonary blood vessels. It can also provide a visual image of the chambers and valves of the heart as well as show the functioning of the heart.

Typically other tests are performed to diagnose the underlying disease associated with pulmonary hypertension. These tests may include electrocardiogram (EKG, ECG), chest X-ray, CT scan of the chest, and a variety of types of blood tests pertinent to the underlying conditions.

In general, the treatment of pulmonary hypertension focuses on treating the underlying cause and managing the symptoms. Early recognition of the disease and appropriate management of the underlying condition is important to slow the rate of progression to an advanced stage. Despite advanced treatment options, there is no a cure for pulmonary hypertension.

As mentioned in previous sections, the treatment of secondary hypertension focuses on treating the underlying cause.

• Regardless of the cause, if hypoxia (low oxygen level) is present, supplemental oxygen may be beneficial.
• If swelling of the legs (edema) or fluid retention due to right-sided heart failure is evident, then treatment with diuretics (water pills) may be advised.
• If congestive heart failure is the cause, then proper management and treatment of this condition are necessary.
• If chronic lung disease is the cause, then it should be treated appropriately.
• Sleep apnea should be properly diagnosed and treated.
• Cases of pulmonary hypertension related to rheumatoid arthritis, lupus, or scleroderma require evaluation and management by a rheumatologist.
• Long-standing and recurrent blood clots to the pulmonary arteries require long-term treatment with blood thinner medications.

In patients with primary pulmonary hypertension, several specific medications are available. The action of these drugs is complicated, but in general, they work by opening up (dilating) the pulmonary arteries to facilitate blood flow by reducing the resistance against it.

Some of the commonly used drugs for the treatment of primary pulmonary hypertension include:

• prostacyclin (Epoprostenol, Flolan),
• bosentan (Tracleer),
• intravenous treprostinil (Remodulin),
• inhaled iloprost (Ventavis),
• sildenafil (Viagra, Revatio),
• calcium channel blockers [such as nifedipine ()Adalat, Adalat CC, Procardia, Procardia XL)],
• sitaxsentan (Thelin) - not FDA approved in the U.S, and
• ambrisentan (Letairis).

At times, these medications can also be used in cases of secondary pulmonary hypertension if it is severe or not well controlled despite adequate management of the underlying condition.

Most patients with pulmonary hypertension can manage the condition at home with regular follow-up visits with their doctor. In cases of mild pulmonary hypertension with minimal or no symptoms, no special treatment other than those required for the underlying cause may be required.

Close follow-up with the treating doctor is very important in patients with pulmonary hypertension. Routine monitoring of symptoms, signs, oxygen level and blood pressure are important components of follow-up for pulmonary hypertension. Repeat echocardiograms or heart catheterizations may also be advised and performed to assess the stability of the pulmonary arterial pressure or other important clinical parameters.

Prevention of pulmonary hypertension may focus on reducing risk factors that may lead to the underlying cause. This is not always possible, especially in situations where the risk factors are not controllable. For example, some conditions, such as lupus, are not preventable. However, if it is diagnosed early and treated appropriately, the chances of subsequent development of pulmonary hypertension may be reduced.

The outlook for pulmonary hypertension depends on the underlying disease and the severity of pulmonary hypertension. Pulmonary hypertension may be a life-threatening condition if diagnosed in late stages or left untreated. The life expectancy of someone with primary pulmonary hypertension may be approximately three years after diagnosis if it goes untreated or sooner if it is severe or there is evidence of right-sided heart failure.