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Primary Pulmonary Hypertension (PPH)
Primary pulmonary hypertension (PPH) is a lung disorder in which the blood
pressure in the pulmonary artery rises above normal levels for no apparent reason.
The pulmonary artery is the blood vessel carrying oxygen-poor blood from the
right ventricle to the lungs. In the lungs, the blood picks up oxygen and then
flows to the left side of the heart, where it is pumped by the left ventricle
to the rest of the body through the aorta.
Hypertension is the medical term for an abnormally high blood pressure. This
abnormally high pressure (pulmonary hypertension) is associated with changes
in the small blood vessels in the lungs, resulting in an increased resistance
to blood flowing through the vessels. The increased resistance places a strain
on the right ventricle, which now has to work harder than usual to move adequate
amounts of blood through the lungs.
Incidence of PPH
The true incidence of PPH is unknown. Between 1967 and 1973, a dramatic increase
in unexplained pulmonary hypertension was reported in central Europe. The rise
was attributed to aminorex fumarate, an amphetamine-like drug introduced in
Europe in 1965 to control appetite. Likewise, recently in the United States
and France, several cases of PPH have been associated with the appetite suppressants,
fenfluramine and dexfenfluramine.
Cause of PPH
The causes of PPH remain unknown. However, there is information regarding
who is most susceptible and what might trigger PPH. Researchers think that in
most people who develop PPH the blood vessels are particularly sensitive to
certain internal or external factors and that they constrict when exposed to
these factors. Diet suppressants, cocaine, HIV, and pregnancy are some of the
factors that are thought to trigger constriction in the pulmonary artery.
Symtoms of PPH
The first symptom of PPH is frequently fatigue. Breathing problems (dyspnea),
dizziness, and fainting spells are also typical early symptoms. Swelling in
the ankles or legs (edema), bluish lips and skin (cyanosis), and chest pain
(angina) are among other symptoms of the disease. Palpitations, a racing pulse
and a gasping for air also sometimes accompany the onset. The more severe the
symptoms, the more advanced the disease. In the more advanced stages, patients
are able to perform only minimal activity and are often symptomatic even when
resting.
Diagnosis of PPH
PPH can be very difficult to diagnose. Therefore, much time can pass between
the time the symptoms of PPH appear and a definite diagnosis is made.
PPH is often diagnosed only after the doctor finds pulmonary hypertension
and excludes other typical reasons for the hypertension.
In ruling out other causes for the hypertension, a doctor first attempts to
determine how well the heart and lungs are performing. If the results of these
tests do not give the doctor enough information, the doctor must perform a cardiac
catheterization. The procedure, discussed below, is the way the doctor can make
certain that the patient's problems are due to PPH and not to some other condition.
Electrocardiogram
The electrocardiogram (ECG) is a record of the electrical activity produced
by the heart. An abnormal ECG may indicate that the heart is undergoing unusual
stress. In addition to the usual ECG performed while the patient is at rest,
the doctor may order an exercise ECG. This ECG helps the doctor evaluate the
performance of the heart during exercise, for example, walking a treadmill.
Echocardiogram
An echocardiogram uses sound waves to map the structure of the heart. An instrument
sends sound waves into the heart, which then are reflected back to form a moving
image of the beating heart's structure on a screen. A record is made on paper
or videotape. The moving pictures show how well the heart is functioning. The
pictures permit the doctor to measure the size of the heart and the thickness
of the heart muscle. The pictures will show that the right heart is enlarged,
while the left heart is either normal or reduced in size, when the patient had
severe pulmonary hypertension.
Pulmonary Function Tests
Pulmonary function tests (PFTs) evaluate lung function. In these procedures,
the patient breathes in and out through a mouthpiece. The patient's breathing
displaces the air held in a container suspended in water. As the container rises
and falls in response to the patient's breathing, the movements produce a record,
or spirogram, that helps the doctor measure air flow electronically.
A mild restriction in air movement is commonly seen in patients with PPH.
Perfusion Lung Scan
The major reason for doing a perfusion scan is to distinguish patients with
PPH from those whose pulmonary hypertension is due to blood clots in the lungs.
Right-Heart Cardiac Catheterization
In right-heart cardiac catheterization, a catheter is threaded into the right
ventricle and pulmonary artery. Most important in terms of PPH is the ability
of the doctor to get a precise measure of the blood pressure in the right side
of the heart and the pulmonary artery with this procedure. It is the only way
to get this measure, and must be performed in the hospital by a specialist.
During catheterization, the doctor can also evaluate the right heart's pumping
ability by measuring the amount of blood pumped out of the right side of the
heart with each heartbeat.
Functional Classification
Once PPH is diagnosed, doctors will usually classify the disease according
to the functional classification system developed by the New York Heart Association.
It is based on patient reports of how much activity they can comfortably undertake.
- Class 1: Patients with no symptoms of any kind, and for
whom ordinary physical activity does not cause fatigue, palpitation, dyspnea,
or anginal pain
- Class 2: Patients who are comfortable at rest but have
symptoms with ordinary physical activity
- Class 3: Patients who are comfortable at rest but have
symptoms with less-than-ordinary effort
- Class 4: Patients who have symptoms at rest
Treatment
Some patients do well by taking medicines that make the work of the right
ventricle easier. Anticoagulants, for example, can decrease the tendency of
the blood to clot, thereby permitting blood to flow more freely. Diuretics
decrease the amount of fluid in the body, further reducing the amount of work
the heart has to do.
Some patients also require supplemental oxygen delivered through nasal prongs
or a mask if breathing becomes difficult; some need oxygen around the clock.
In severely affected cases, a heart-lung, single lung, or double lung transplantation
may be appropriate.
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