Cor pulmonale or pulmonary heart disease is enlargement of the
right ventricle of the heart as a response to increased resistance or
high blood pressure in the lungs (pulmonary hypertension).
Chronic cor pulmonale usually results in right ventricular
hypertrophy (RVH), whereas acute cor pulmonale usually results in
dilatation.
Hypertrophy is an adaptive response to a long-term increase in
pressure. Individual muscle cells grow larger (in thickness) and change
to drive the increased contractile force required to move the blood
against greater resistance.
Dilatation is a stretching (in length) of the ventricle in response
to acute increased pressure, such as when caused by a pulmonary
embolism.
To be classified as cor pulmonale, the cause must originate in the
pulmonary circulation system. Two major causes are vascular changes as a
result of tissue damage (e.g. disease, hypoxic injury, chemical agents,
etc.), and chronic hypoxic pulmonary vasoconstriction. RVH due to a
systemic defect is not classified as cor pulmonale.
If left untreated, cor pulmonale can lead to right-heart failure and death.
The heart and lung are intricately related. Whenever the heart is
affected by disease, the lungs will follow and vice versa. Pulmonary
heart disease is by definition a condition when the lungs cause the
heart to fail.
The heart has two pumping chambers. The left ventricle pumps blood
throughout the body. The right ventricle pumps blood to the lungs where
it is oxygenated and returned to the left heart for distribution. In
normal circumstances, the right heart pumps blood into the lungs without
any resistance. The lungs usually have minimal pressure and the right
heart easily pumps blood through.
However when there is lung disease present, like emphysema, chronic
obstructive lung disease (COPD) or pulmonary hypertension- the small
blood vessels become very stiff and rigid. The right ventricle is no
longer able to push blood into the lungs and eventually fails. This is
known as pulmonary heart disease. Pulmonary heart disease is also known
as right heart failure or cor pulmonale. The chief cause of right heart
failure is the increase in blood pressure in the lungs (pulmonary
artery).
Symptoms
The symptoms of pulmonary heart disease depend on the stage of the
disorder. In the early stages, one may have no symptoms but as pulmonary
heart disease progresses, most individuals will develop the symptoms
like:
• Shortness of breath which occurs on exertion but when severe can occur at rest
• Wheezing
• Chronic wet cough
• Swelling of the abdomen with fluid (ascites)
• Swelling of the ankles and feet (pedal edema)
• Enlargement or prominent neck and facial veins
• Raised Jugular Venous Pulse (JVP)
• Enlargement of the liver
• Bluish discoloration of face
• Presence of abnormal heart sounds
• Possible bi-phasic atrial response shown on an EKG due to hypertrophy
Diagnosis
In many cases, the diagnosis of pulmonary heart disease is not easy as
both the lung and heart disease can produce similar symptoms. Most
patients undergo an ECG, chest X ray, echocardiogram, CT scan of the
chest and a cardiac catheterization. During a cardiac catheterization, a
small flexible tube is inserted from the groin and under x ray guidance
images of the heart are obtained. Moreover the technique allows
measurement of pressures in the lung and heart which provide a clue to
the diagnosis.
Treatment
Elimination of the cause is the most important intervention. Smoking
must be stopped, exposure to dust, flames, household smoke and to cold
weather is avoided. If there is evidence of respiratory infection, it
should be treated with appropriate antibiotics after culture and
sensitivity. Diuretics for RVF, In pulmonary embolism, thrombolysis
(enzymatic dissolution of the blood clot) is advocated by some
authorities if there is dysfunction of the right ventricle, and is
otherwise treated with anticoagulants. In COPD, long-term oxygen therapy
may improve cor pulmonale.
Cor pulmonale may lead to congestive heart failure (CHF), with
worsening of respiration due to pulmonary edema, swelling of the legs
due to peripheral edema and painful congestive hepatomegaly (enlargement
of the liver due to tissue damage as explained in the Complications
section. This situation requires diuretics (to decrease strain on the
heart), sometimes nitrates (to improve blood flow), phosphodiesterase
inhibitors such as sildenafil or tadalafil and occasionally inotropes
(to improve heart contractility). CHF is a negativeprognostic indicator
in cor pulmonale.
Oxygen is often required to resolve the shortness of breath. Plus,
oxygen to the lungs also helps relax the blood vessels and eases right
heart failure. Oxygen is given at the rate of 2 litres per minute.
Excess oxygen can be harmful to patients because hypoxia is the main
stimulus to respiration.
If such hypoxia is suddenly corrected by overflow of oxygen, such
stimulus to the respiratory center is suddenly withdrawn and respiratory
arrest occurs. When wheezing is present, majority of the patients
require bronchodilators. A variety of drugs have been developed to relax
the blood vessels in the lung. Calcium channel blockers are used but
only work in a few cases. Other novel medications that need to be
inhaled or given intravenously include prostacyclin derivatives.
Cases of COPD with chronic corpulmonale present with secondary
polycythemia, if severe it may increase the blood viscosity and
contribute to pulmonary hypertension. If hematocrit(PCV) is above 60%,
then it is better to reduce the red blood cell count by phlebotomies.
Mucolytic agents like bromhexine and carbocisteine help bring out excessive bronchial secretions more easily by coughing.
All patients with pulmonary heart disease are maintained on blood thinning medications to prevent formation of blood clots.