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).
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:
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.
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.