Cor pulmonale is a Latin word that means "pulmonary heart," its definition varies, and presently, there is no consensual definition.
Cor pulmonale can be defined as an alteration in the structure (e.g., hypertrophy or dilatation) and function of the right ventricle (RV) of the heart caused by a primary disorder of the respiratory system resulting in pulmonary hypertension.
Right-sided heart failure secondary to left-sided heart failure, or congenital heart disease is not considered cor pulmonale.
Pulmonary hypertension is associated with diseases of the lung (e.g., chronic obstructive pulmonary disease, interstitial lung disease), vasculature (e.g., idiopathic pulmonary arterial hypertension), upper airway (e.g., obstructive sleep apnea), or chest wall (e.g., kyphoscoliosis). Diseases that damage lungs are autoimmune (e.g., scleroderma), cystic fibrosis, and obesity hypoventilation syndrome are also lead to pulmonary hypertension.
Massive pulmonary embolism is the most common cause of acute cor pulmonale.
A massive pulmonary embolism can mimic a myocardial infarction with elevated troponins, ST changes, chest pain, and shortness of breath.
Chronic obstructive pulmonary disease (COPD) is the most common cause of cor pulmonale. The severity of cor pulmonale appears to correlate with the magnitude of hypoxemia, hypercapnia, and airflow obstruction.
In most patients with COPD, cor pulmonale tends to be accompanied by mild pulmonary hypertension (i.e., mean pulmonary artery pressure 40 mmHg or less).
The exact prevalence of cor pulmonale is difficult to determine, as physical examination and routine tests are relatively insensitive for the detection of pulmonary hypertension and RV dysfunction. Cor pulmonale is estimated to account for 6% to 7% percent of all types of adult heart disease in the United States. Globally, the incidence of cor pulmonale varies widely among countries, depending on the prevalence of cigarette smoking, air pollution, and other risk factors for various lung diseases.
The pathophysiology of cor pulmonale is a result of increased right-sided filling pressures from pulmonary hypertension that is associated with diseases of the lung.
Under normal physiologic conditions, the right ventricle pumps against a low-resistance circuit.
Normal pulmonary vascular resistance is approximately one-tenth the resistance of the systemic arteries. Chronic hypoxemia leading to chronic vasoconstriction produces smooth muscle proliferation in small pulmonary arteries. Hypoxemia produces changes in vascular mediators such as Nitric Oxide, Endothelin1 (ET1) and platelet-derived growth factors (PDGf A and B). Nitric oxide is a vasodilator; hypoxemia reduces endothelial cell production of nitric oxide and results in impaired smooth ms relaxation.
The initial pathophysiologic event in the production of cor pulmonale is an elevation of the pulmonary vascular resistance. As the resistance increases, the pulmonary arterial pressure rises, and the right ventricular work increases leading to right ventricular enlargement (e.g., thickening, dilation, or both).
Symptoms may include dyspnea on exertion (most common), fatigue, lethargy, exertional syncope and exertional chest pain, abdominal edema or distension, and lower extremity edema.
The clinical signs occur late, being observed at an advanced stage of the disease far after the development of pulmonary hypertension.
Physical findings may include:
Laboratory investigations are directed toward defining the potential underlying etiologies as well as evaluating the complications of cor pulmonale. These include:
Treatment is aimed primarily at treating the underlying condition; the aim is improving oxygenation and right ventricular (RV) function by increasing RV contractility and decreasing pulmonary vasoconstriction.
Oxygen therapy relieves hypoxemic pulmonary vasoconstriction, which then improves cardiac output, lessens sympathetic vasoconstriction, alleviates tissue hypoxemia, and improves renal perfusion.
Diuretics are used to decrease the elevated right ventricular (RV) filling volume in patients with chronic cor pulmonale.
The use of cardiac glycosides, such as digitalis in patients with cor pulmonale has been controversial, and the beneficial effect of these drugs is not as obvious as in the setting of left heart failure. Nevertheless, studies have confirmed a modest effect of digitalis on the failing right ventricle in patients with chronic cor pulmonale.
The prognosis of cor pulmonale is variable-dependant upon the underlying pathology. Development of cor pulmonale as a result of a primary pulmonary disease usually heralds a poorer prognosis.