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Q: What is the reason for cor pulmonale?
Krishna: Cor pulmonale is a Latin word that means "pulmonary heart," its definition varies, and presently, there is no consensual definition.
Cor pulmonale is a condition that causes the right side of the heart to fail. Long-term high blood pressure in the arteries of the lung and right ventricle of the heart can lead to cor pulmonale.
Cor pulmonale is dilatation and hypertrophy of the right heart in response to pulmonary hypertension(1). Cor pulmonale refers to altered structure or function of the right ventricle resulting from pulmonary hypertension (PH) associated with chronic lung disease.
Right-sided, or right ventricular, heart failure is defined as a process, not a disease. This conditions is also know as cor pulmonale. It often occurs when the weakened and/or stiff left ventricle loses the ability to efficiently pump blood to the rest of the body.
What diseases cause it? Pulmonary embolism (more common) and acute respiratory distress syndrome (ARDS). The underlying pathophysiology in a massive pulmonary embolism causing cor pulmonale is the sudden increase in pulmonary resistance.
There are two sub-types of cor pulmonale (1):
Cor pulmonale can be acute or chronic.
In acute cor pulmonale the afterload to the right ventricle can rise in a matter of minutes (e.g., massive pulmonary embolism) giving very little room for compensation. The result will be acute right ventricular dilatation and failure, its severity depending primarily on the degree of acute PA hypertension.
In chronic cor pulmonale, an increase of right ventricular afterload in the face of slowly developing PA hypertension (e.g., hypoxemia in chronic obstructive pulmonary disease [COPD]) generates a compensatory response of the right ventricle (see later) that will preserve the stroke volume until either the afterload increases excessively or the myocardium fails because of ischemia or other pathologic condition.
Chronic cor pulmonale: This form of chronic right heart failure is a consequence of chronic pulmonary hypertension. The right ventricle is dilatated, and its wall is thickened. The most common cause of chronic cor pulmonale is left heart failure. Other causes of chronic cor pulmonale are mostly related to various lung diseases. Alveolar hypoxemia is a potent stimulator of pulmonary vascular constriction, and this ultimately leads to irreversible changes in the vessel wall and narrowing of the pulmonary artery tree. Destruction of alveolar septa and the reduction of the capillary bed in the lungs are other important mechanisms.The combination of alveolar hypoventilation, chronic hypoxemia, and pulmonary vasoconstriction will result in up to 70% of patients eventually developing pulmonary hypertension and hypertrophy of the right ventricle (cor pulmonale). A clear relationship has been demonstrated between the degree of hypoxemia and pulmonary artery pressure. Echocardiography is the most sensitive noninvasive technique for the early recognition and monitoring of cor pulmonale. For practical purposes, cor pulmonale is assumed to be present when one or more of the following is present: right ventricular hypertrophy on ECG, Pao2 less than 50 mm Hg, signs of heart failure, radiographic evidence of enlarged pulmonary arteries, and forced vital capacity greater than 60% predicted. After the onset of right-sided failure, most patients are significantly disabled and mean survival is 8 months (range, 1 to 63 months). The presence of pulmonary hypertension has been cited as one of the referral criteria for transplantation in CF patients (1).
Lung disorders cause pulmonary hypertension that can lead to cor pulmonale by several mechanisms (2):
Vasoconstriction caused by hypoxia, hypercapnia, or both
Increased alveolar pressure (eg, in COPD, during mechanical ventilation)
Medial hypertrophy in arterioles (often a response to pulmonary hypertension due to other mechanisms)
Treatment (2): Treatment of causes
Treatment of cor pulmonale is difficult; it focuses on the cause (see table ), particularly alleviation or moderation of hypoxia. Early identification and treatment are important before structural changes become irreversible.
If peripheral edema is present, diuretics may seem appropriate, but they are helpful only if LV failure and pulmonary fluid overload are also present. Diuretics should be used cautiously because small decreases in preload often worsen cor pulmonale. Pulmonary vasodilators (eg, hydralazine, calcium channel blockers, nitrous oxide, prostacyclin, phosphodiesterase inhibitors), although beneficial in primary pulmonary hypertension, are not effective. Bosentan, an endothelin receptor blocker, also may benefit patients with primary pulmonary hypertension, but its use is not well studied in cor pulmonale.
Phlebotomy during hypoxic cor pulmonale has been suggested, but the benefits of decreasing blood viscosity are not likely to offset the harm of reducing oxygen-carrying capacity unless significant polycythemia is present. For patients with chronic cor pulmonale, long-term anticoagulants reduce risk of venous thromboembolism.
Please note that this answer is only for informative purposes. Patients should consult a well qualified medical doctor for diagnosing and treatment purposes. The Internet is not the right place to consult people and come to a conclusion for any medical condition.