RISK FACTORS : Tobacco abuse, Living at high altitudes, Industrial exposures
Medical Care: Medical therapy for chronic cor pulmonale is generally focused on treatment of the underlying pulmonary disease and improving oxygenation and RV function by increasing RV contractility and decreasing pulmonary vasoconstriction. However, the approach might be different to some degree in an acute setting with priority given to stabilizing the patient.
Cardiopulmonary support for patients experiencing acute cor pulmonale with resultant acute RV failure includes fluid loading and vasoconstrictor (eg, epinephrin) administration to maintain adequate blood pressure. Of course, the primary problem should be corrected, if possible. For example, for massive pulmonary embolism, consider administration of anticoagulation, thrombolytic agents or surgical embolectomy, especially if circulatory collapse is impending, consider bronchodilation and infection treatment in patients with COPD and consider steroid and immunosuppressive agents in infiltrative and fibrotic lung diseases.
Oxygen therapy, diuretics, vasodilators, digitalis, theophylline, and anticoagulation therapy are all different modalities used in the long-term management of chronic cor pulmonale.
" Oxygen therapy is of great importance in patients with underlying COPD, particularly when administered on a continuous basis. With cor pulmonale, the partial pressure of oxygen (PO2) is likely to be below 55 mm Hg and decreases further with exercise and during sleep.
Oxygen therapy relieves hypoxemic pulmonary vasoconstriction, which then improves cardiac output, lessens sympathetic vasoconstriction, alleviates tissue hypoxemia, and improves renal perfusion. The Nocturnal Oxygen Therapy Trial (NOTT), a multicenter randomized trial, showed that continuous low-flow oxygen therapy for patients with severe COPD resulted in significant reduction in the mortality rate. In general, in patients with COPD, long-term oxygen therapy is recommended when PaO2 is less than 55 mm Hg or O2 saturation is less than 88%. However, in the presence of cor pulmonale or impaired mental or cognitive function, long-term oxygen therapy can be considered even if PaO2 is greater than 55 mm Hgor O2 saturation is greater than 88%.
Although it is not clear whether oxygen therapy has a mortality rate benefit in patients with cor pulmonale due to pulmonary disorders other than COPD, it may provide some degree of symptomatic relief and improvement in functional status. Therefore, oxygen therapy plays an important role in both the immediate setting and long-term management, especially in patients who are hypoxic and have COPD.
" Diuretics are used in the management of chronic cor pulmonale, particularly when the right ventricular filling volume is markedly elevated and in the management of associated peripheral edema. Diuretics may result in improvement of the function of both the right and left ventricles; however, diuretics may produce hemodynamic adverse effects if they are not used cautiously. Excessive volume depletion can lead to a decline in cardiac output. Another potential complication of diuresis is the production of a hypokalemic metabolic alkalosis, which diminishes the effectiveness of carbon dioxide stimulation on the respiratory centers and lessens ventilatory drive. The adverse electrolyte and acid-base effect of diuretic use can also lead to cardiac arrhythmia, which can diminish cardiac output. Therefore, diuresis, while recommended in the management of chronic cor pulmonale, needs to be used with great caution.
" Vasodilator drugs have been advocated in the long-term management of chronic cor pulmonale with modest results. Calcium channel blockers, particularly oral sustained-release nifedipine and diltiazem, can lower pulmonary pressures, although they appear more effective in primary rather than secondary pulmonary hypertension. Other classes of vasodilators, such as beta agonists, nitrates, and angiotensin-converting enzyme (ACE) inhibitors have been tried but, in general, vasodilators have failed to show sustained benefit in patients with COPD and they are not routinely used. A trial of vasodilator therapy may be considered only in patients with COPD with disproportionately high pulmonary blood pressure.
Beta-selective agonists have an additional advantage of bronchodilator and mucociliary clearance effect. Right heart catheterization has been recommended during initial administration of vasodilators to objectively assess the efficacy and detect the possible adverse hemodynamic consequences of vasodilators. The Food and DrugAdministration (FDA) has approved epoprostenol, treprostinil, bosentan, and iloprost for treatment of primary pulmonary hypertension. Epoprostenol, treprostinil, and iloprost are prostacyclin PGI2 analogues and have potent vasodilatory properties. Epoprostenol and treprostinil are administered intravenously and iloprost is an inhaler. Bosentan is a mixed endothelin-A and endothelin-B receptor antagonist indicated for pulmonary arterial hypertension (PAH), including primary pulmonary hypertension (PPH). In clinical trials, it improved exercise capacity, decreased rate of clinical deterioration, and improved hemodynamics. PDE5 inhibitor sildenafil has also been intensively studied and recently approved by the FDA for treatment of pulmonary hypertension based on a large randomized study. Sildenafil promotes selective smooth muscle relaxation in lung vasculature. Not enough data are available regarding the efficacy of these drugs in patients with secondary pulmonary hypertension such as in patients with COPD.
" 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. It must be used cautiously, however, and should not be used during the acute phases of respiratory insufficiency when large fluctuations in levels of hypoxia and acidosis may occur. Patients with hypoxemia or acidosis are at increased risk of developing arrhythmias due to digitalis through different mechanisms including sympathoadrenal stimulation.
" In addition to bronchodilatory effect, theophylline has been reported to reduce pulmonary vascular resistance and pulmonary arterial pressures acutely in patients with chronic cor pulmonale secondary to COPD. Theophylline has a weak inotropic effect and thus may improve right and left ventricular ejection. As a result, considering the use of theophylline as adjunctive therapy in the management of chronic or decompensated cor pulmonale is reasonable in patients with underlying COPD.
" Anticoagulation with warfarin is recommended in patients at high risk for thromboembolism. The beneficial role of anticoagulation in improving the symptoms and mortality in patients with primary pulmonary arterial hypertension clearly was demonstrated in a variety of clinical trials. The evidence of benefit, however, has not been established in patients with secondary pulmonary arterial hypertension. Therefore, anticoagulation therapy may be used in patients with cor pulmonale secondary to thromboembolic phenomena and with underlying primary pulmonary arterial hypertension.
Surgical Care:
" Phlebotomy is indicated in patients with chronic cor pulmonale and chronic hypoxia causing severe polycythemia, defined as hematocrit of 65 or more. Phlebotomy results in a decrease in mean pulmonary artery pressure, a decrease in mean pulmonary vascular resistance, and an improvement in exercise performance in such patients. There is, however, no evidence of improvement in survival. Generally, phlebotomy should be reserved as an adjunctive therapy for patients with acute decompensation of cor pulmonale and patients who remain significantly polycythemic despite appropriate long-term oxygen therapy. Replacement of the acute volume loss with a saline infusion may be necessary to avoid important decreases in systemic blood pressure.
" No surgical treatment exists for most diseases that cause chronic cor pulmonale. Pulmonary embolectomy is efficacious for unresolved pulmonary emboli, which contribute to pulmonary hypertension. Uvulopalatopharyngoplasty in selected patients with sleep apnea and hypoventilation may relieve cor pulmonale. Single-lung, double-lung, and heart-lung transplantation are all used to salvage the terminal phases of several diseases (eg, primary pulmonary hypertension, emphysema, idiopathic pulmonary fibrosis, cystic fibrosis) complicated by cor pulmonale. Apparently, lung transplantation will lead to a reversal of right ventricular dysfunction from the chronic stress of pulmonary hypertension. Strict selection criteria for lung transplant recipients must be met, however, because of the limited availability of organ donors.
MEDICATION :
1. DIURETICS
- FRUSEMIDE
2. CALCIUM CHANNEL BLOCKERS :
- NIFEDIPINE
3. CARDIAC GLYCOSIDES :
- DIGOXIN
4. ANTICOAGULANTS : TO REDUCE INCIDENCE OF EMBOLI FORMATION
- WARFARIN
5. METHYL XANTHINES ( BRONCHODILATORS ) :
- THEOPHYLLINE
6. ENDOTHELIN RECEPTOR ANTAGONISTS : COMPETITIVELY BIND TO ENDOTHELIN-1 RECEPTORS CAUSING REDUCTION IN PULMONARY ARTRY PRESSURE, PULMNARY VASCULAR RESISTANCE & MEAN RT. ATRIAL PRESSURE
- BOSENTAN