Pulmonary
- Critical Care Associates
of East Texas
Jeffrey M.
Shea, M.D., F.C.C.P.
Venkatesh Donty, M.D.
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Jeffrey M.
Shea, M.D., F.C.C.P. |
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Pulmonary Hypertension
What
is Pulmonary Hypertension? This is a disease in which there is a persistent elevation of pressure through the lung circulation. without an identifiable cause. It is a rare lung disorder occurring as a primary idiopathic disease or as a complication of respiratory and cardiac diseases. In pulmonary hypertension the blood
pressure in the pulmonary artery rises far above normal levels.
The pulmonary artery carries oxygen-poor blood from the right ventricle,
one of the pumping chambers of the heart, 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 abnormally high
blood pressure. Normal mean
pulmonary-artery pressure is 14 mmHg at rest.
In the patient with pulmonary hypertension the mean blood pressure in the
pulmonary artery is greater than 25 mmHg at rest and 30 mmHg during exercise.
The abnormally high blood pressure is associated with changes in the
small blood vessels in the lungs, resulting in an increased resistance to blood
flowing through the vessels. With an increased resistance it
places a strain on the right ventricle, which has to work harder than usual
against the resistance to move adequate amounts of blood through the lungs. Signs and Symptoms Dyspnea is the main symptom of pulmonary
hypertension, occurring in more than 95% of patients. Breathlessness is the presenting symptom in 60% of patients
and usually is noted first on exertion, and eventually occurs at rest.
The most likely cause for dyspnea in pulmonary hypertension is the
inadequacy of cardiac output compared to the metabolic requirements.
Along with dyspnea, patients may have fatigue and weakness. Patients may also complain of chest pain.
This can frequently occur on exertion and radiate to the left shoulder,
and may be relieved by rest. Syncope (fainting) occurs in some patients and
may be the initial manifestation. This
symptom is experienced first on exertion but may happen at rest.
The syncope may be caused by a decrease in cerebral blood flow that
follows an increase in pulmonary artery pressure and a fall in cardiac output. Hemoptysis may also be associated with
pulmonary hypertension. This may
stem from microvascular aneurysms that rupture under the high pulmonary artery
pressure. In early pulmonary hypertension patients may
not show any physical signs. Patients
with severe disease may have cold hands and feet, peripheral pulse diminished,
blood pressure is low, and the pulse pressure is reduced. On listening to the chest, there may be an
irregular heartbeat detected, such as a murmur. Cyanosis occurs with variable frequency and is likely to be a late onset of symptoms. It is most likely to occur after exercise but can be present at rest. Diagnosing Pulmonary Hypertension The diagnosis of Pulmonary Hypertension is very rarely picked up during a routine medical examination. Pulmonary Hypertension is a diagnosis of exclusion. This is diagnosed only after the doctor finds an elevated blood pressure in the lungs and excludes or cannot find other reasons for the hypertension, such as chronic obstructive pulmonary disease (chronic bronchitis and emphysema), blood clots in the lung (pulmonary thromboemboli), or forms of congenital heart disease. TestingSeverity of pulmonary hypertension may be assessed by examination, but several diagnostic procedures may be required to evaluate the precise amount of hypertension. Blood
studies- a complete blood count is helpful in documenting polycythemia,
which is present in patients with a decreased oxygen level in pulmonary
hypertension. Arterial blood gases
may also be obtained; they usually reveal a low PCO2 and a normal pH
(respiratory alkalosis). The PO2
may be normal or abnormal; the alveolar-to-arterial PO2 difference is usually
increased. Chest
x-ray- these films will help show any potential underlying conditions such
as parenchymal lung disease. In
patients with pulmonary hypertension the chest x-ray reveals protrusion of the
main pulmonary artery, increased width of the descending branch of the right
pulmonary artery, and an increase in the cardiothoracic ratio. Pulmonary
Function Tests- this test usually reveal normal expiratory flow rates with
normal or mildly reduced lung volumes. The
diffusing capacity for carbon monoxide is often reduced to a mild or moderate
degree. Electrocardiogram
(ECG or EKG)- this is a record of the electrical activity produced by the heart.
An abnormal ECG may indicate that the heart is undergoing unusual stress.
The ECG is usually done at rest but can also be done during exercise.
The doctor can evaluate the heart during exercise and be done by walking
on a treadmill. Echocardiogram-
this
is a sound wave to map the structure of the heart by placing a device on the
patient’s chest. The 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 TV screen.
A record is made on paper or videotape.
The moving pictures show how well the heart is functioning.
The still pictures permit the doctor to measure the size of the heart and
the thickness of the heart muscle; in the patient with severe pulmonary
hypertension, the still pictures will show that the right heart is enlarged,
while the left heart is either normal or reduced in size.
This test is helpful in excluding some other causes of pulmonary
hypertension and can be useful in monitoring the response to treatment. Perfusion
Lung Scan- this shows the pattern of blood flow in the lungs; it can also tell
the doctor whether a patient has large blood clots in the lungs.
During the scan the doctor injects a radioactive dye into a vein.
After injection the chest is scanned for radioactivity. Areas in the lung where blood clots are blocking the flow of
blood will show up as blank or clear areas.
There are two patterns of pulmonary perfusion seen in patients with
primary pulmonary hypertension. One
pattern is of blood distribution; the other shows a scattering of patchy
abnormalities in blood flow. A
reason for doing a perfusion scan is to distinguish patients with primary
pulmonary hypertension from with pulmonary hypertension due to blood clots in
the lungs. Right
Heart Catheterization- with this procedure the doctor places a thin, flexible tube,
or catheter, through an arm, leg, or neck vein. He then threads the catheter into the right ventricle and
pulmonary artery. The doctor is
able to get a precise measure of the blood pressure in the right side of the
heart and the pulmonary artery. This
is the only way to get this pressure and it is performed in the hospital.
The doctor is also able to evaluate the right heart’s pumping ability;
this is done by measuring the amount of blood pumped out of the right side of
the heart with each heartbeat. WHO Classification of Pulmonary Hypertension
Functional Classification Once the diagnosis has been made, the
doctor may classify the disease. It
is based on patient reports of how much activity they can comfortably undertake. ·
Class
1-
is assigned to patients with no symptoms of any kind, and for whom ordinary
physical activity does not cause fatigue, palpitation, dyspnea, or anginal pain. ·
Class
2- is
assigned to patients who are comfortable at rest but have symptoms with ordinary
physical activity. ·
Class
3- is
assigned to patients who are comfortable at rest but have symptoms with
less-than-ordinary effort. ·
Class
4-
is assigned to patients who have symptoms at rest. TreatmentPatients should be encouraged to avoid circumstances that may increase pulmonary artery pressure and decrease cardiac output. One stimulus that may exacerbate pulmonary hypertension is high altitudes. Patients with cardiopulmonary disease should be treated with oxygen for low oxygen levels, and cigarette smoking should be avoided. Drugs that have vasoconstrictive actions should also be avoided. So should barbiturates and other drugs that depress the heart function. Women that are of childbearing age should consult with a doctor before getting pregnant. Blood thinners may be given to patients to help reduce the risk of blood clotting, and enable the blood to travel through the lung circulation better. Vasodilators such as sublingual
isoproterenol, phentolamine, hydralazine, diazoxide, nifedipine, captopril,
nitrates, and prostaglandin inhibitors have been used for many years.
These medications should be used cautiously though and under medical
supervision. Heart-lung transplant is the remaining
therapy for patients that did not respond to vasodilators. SummaryPrimary pulmonary hypertension can be a severely debilitating disease. Some patients benefit from vasodilators; others gain extra time with good medical management, and others have been helped by combined heart-lung or lung transplantation. Further research and better tools for noninvasive assessment are ongoing to help better treat this illness.
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