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How are pulmonary hypertension patients treated and why don't they all get treated in the same way?

Though we refer to pulmonary hypertension by just one name, each person with the disease is different and responds differently to different medications. Your medical team of doctors and nurses will work with you to determine exactly which medications are right for you. Some patients who are found to have very mild pulmonary hypertension are not put on any medications and their symptoms and pressures are monitored carefully for worsening. Other patients are treated with only one medication, and in contrast, some PAH patients may be on several different types of medications that address different problems that occur with PAH all at the same time. The main types of medications used are diuretics, anticoagulants, vasodilators, prostacyclin analogues, and endothelin receptor antagonists.

Diuretics are medications used to rid the body of excess fluid. As discussed previously, in PAH, the high PA pressures can cause strain on the right ventricle. In turn, this causes fluid to build up upstream of the right ventricle, usually in the most dependent portions of your body, i.e. the legs. To help remove this excess fluid (edema), diuretics may be employed. Typically it is very helpful to measure your weight every day while you are on diuretics. We describe a patient's baseline weight as their "dry" weight and it is important to follow this closely. Additionally, diet can affect your weight – particularly salty foods. Salty foods can cause you to retain fluids and may make the dose of diuretic you are taking ineffective.

Since patients with PAH are more prone to developing blood clots in the pulmonary vessels and in the deep veins of the extremities, they are often started on anticoagulants or blood thinners (see quest. 4), such as warfarin or coumadin. These medications have to be monitored closely by a blood test called the prothrombin time. Patients who are on anticoagulants have a predisposition to bleeding so they have to be careful with even minor trauma or cuts to the skin.

When you are diagnosed with pulmonary hypertension, you will likely undergo a right-heart catheterization. During this procedure, the doctor will measure the pressures in the chambers of the heart and the pulmonary arteries. In addition, they can do tests with certain medications to observe their effect on these pressures. These medications are short-acting vasodilators (medications that work directly on the blood vessels and cause them to dilate, thereby reducing the pressure). The medications that are usually administered during this test are inhaled nitric oxide, adenosine, or prostacyclin analogues. Your response to these vasodilators will help determine which medication will most benefit you.

Often, inhaled nitric oxide is used as the test vasodilator. It is administered and the change in your pulmonary pressures is measured. If there is significant drop in these pressures to a normal or nearly normal level, you are considered a "responder" to the vasodilator trial, and studies have shown you can be treated with a type of blood pressure medication that acts as a vasodilator called an oral calcium channel blocker, such as nifedipine, amlodipine, or diltiazem. Typically, most patients do not have a dramatic drop in their pulmonary artery pressures in response to the test vasodilator. If your vasodilator trial does not result in a significant drop in pulmonary arterial pressures, you may be termed a "nonresponder." In this case, alternative agents, such as a prostacyclin, an endothelin receptor antagonist, a phosphodiesterase inhibitor, or a soluble guanylate cyclase stimulator should be considered for therapy. These are also used if your PAH is more advanced and causing more significant symptoms requiring multiple medications or if you were on a calcium channel blocker that has not been working.

The exact reason why some patients are responders and others are not is not known for sure. In many large research studies over many years, it has been found that relatively few patients (probably only between 5-10% of all PAH patients) are true responders. One theory for this is that most patients start out as responders, with their blood still not so severely affected that they can still "react" to the short-acting pulmonary vasodilator. As the disorder progresses, the blood vessels get stiffer and stiffer and the pulmonary arteries lose their reactivity. Some PAH patients have initially been found to be non-responders but then over time with chronic medical therapy (typically with one of the prostacyclins), they are then found to be a responder on a subsequent catheterization study. We don't yet know exactly what the significance of this is, but we believe that it suggests improvement in the disease in the pulmonary arteries.

The effectiveness of these medications can be measured in several ways: qualitatively by improvement or stabilization in symptoms; and quantitatively by measuring your PA pressures by echocardiogram or repeat right-heart catheterization, or through a functional study such as a 6 minute walk test.

Many patients will have functional improvement, that is they feel better and do more, without much change in the actual pulmonary artery pressures. The reasons for this are not certain, but we think the medications may be allowing the right heart to adapt to generating the higher pressures needed for improved flow through the pulmonary arteries without straining.