بسم ال الرحمن الرحيم Cor pulmonale ByProf. Dr. Rasheed Abd El Khalek .M. D Head Of Internal Medicine & Intensive Care Department
Definitions Cor pulmonale is a latin word means ”pulmonary heart” . The world Health Organizaton in 1963 adopted this definition of cor pulmonale :” hypertrophy of the right ventricle resulting from diseases affecting the function and/or structure of the lungs, except when these pulmonary alterations are the result of diseases that primarily affect the left side of the heart , as congenital heart diseases” Cor pulmonale is a disease of the right ventricle characterized by hypertrophy and dilation that results from diseases directly affecting the lung parenchyma or lung vasculature. Of note ,right heart failure need not be present in cor pulmonale .
Subtypes Of Cor Pulmonale Cor pulmonale can be either acute or chronic in development. Acute cor pulmonale is the result of a sudden increase in right ventricular pressure, as seen in massive pulmonary embolism or acute respiratory distress syndrome. Chronic cor pulmonale can be further characterized by hypoxic or vascular obliterans pathophysiology. The most common disease process associated with hypoxic subtype is chronic obstructive pulmonary disease (COPD). The most common process associated with obliterans subtype is pulmonary thromboembolic disease.
Pathophysiology Under normal phsyologic conditions, the right ventricle pumps against a low- resistance circuit. Normal pulmonary vascular resistance is approximately one-tenth the resistance of the systemic arteries. The right ventricle is thin walled and able to accommodate considerable changes in volume without large changes in pressure. Increased cardiac output leads to recruitment of underperfused pulmonary vessels and distention of other pulmonary vessels. The initial pathophysiologic event in the production of cor pulmonale is elevation of the pulmonary vascular resistance. As the resistance increases, the pulmonary arterial pressure rises, right ventricular work increases, right ventricular hypertrophy (i.e.,thickening, dilation, or both ). Right ventricular failure occurs when compensation through dilation and hypertrophy are exhausted.
Causes Any process that results in pulmonary hypertension can cause cor pulmonale. Pulmonary hypertension is defined as mean pulmonary artery pressure >20 mmHg at rest or >30 mmHg with exercise.
Pathophysiology of pulmonary hypertension1. Hypoxic pulmonary vasoconstriction and arterial occlusion are the major causes of pulmonary hypertension.2. Both produce reduced blood flow with increased vascular resistance.3. Acute hypoxic pulmonary vaso –constriction optimizes ventilation – perfusion relationships when regional ventilation demands in the lung are not met.
4. However, chronic hypoxemia leading to chronic vasoconstriction produces smooth ms proliferation in small pulmonary arteries.5. Decreased luminal cross sectional diameter leads to increased resistance and increased pulmonary artery pressure.
6. These architectural changes in pulmonary arteries may promote platelet aggregation and activation.7. This leads to thrombi formation that further increases pulmonary vascular resistance and pulmonary hypertension.
8. Hypoxemia produces changes in vascular mediators such as Nitric Oxide, Endothelin1 (ET1) and platelet derived growth factors (PDGf A and B).9. Nitric oxide is a vasodilator; hypoxemia reduces endothelial cell production of nitric oxide and results in impaired smooth ms relaxation.
10. Hypoxemia increases ET1 production and PDGF A and B .11. ET1 is apotent vasoconstrictor, and PDGF A and B results in pulmonary vascular remodeling.12. All causes increased pulmonary artery resistance and causes pulmonary hypertension.
Presentation The signs and symptoms of cor pulmonale are often subtle unless the disease process becomes far advanced. In addition, clinicians tend to focus on the disease giving rise to cor pulmonale rather than on cor pulmonale itself. Manifestations of cor pulmonale are similar to those of right side heart failure.
:Symptoms of Cor Pulmonale Fatigability Dyspnea on exertion Syncope Chest pain Palpitation Abdominal edema or distension Lower extremity edema
Clinical Signs Of Cor :Pulmonale Accentuated A wave of the jugular venous pulsations Prominent jugular V wave, indicating the presence of tricuspid regurgitation Palpable left parasternal lift Accentuated pulmonic component of the second heart sound Right sided S4 heart sound
Murmurs of tricuspid and pulmonic insufficiency Dependent prepheral edema and hepatomegaly
The mortality associated with cor pulmonale Patients with COPD have a 60% 5-year survival rate, whereas patients with COPD and pulmonary artery pressure in excessof 25 mmHg have a survival of only 36%. The 5-year survival rate for patients with COPD who develop preipheral edema is approximately 30%. It is unclear whether pulmonary artery hypertension is the cause of death or whether it is a marker of increased motality.
Electrocardiography criteria of right ventricular hypertrophy Right axis deviation. P pulmonale (large P wave ) in the inferior and anterior leads “ right atrial enlargement “. Right bundle branch block. Right precordial T-wave inversions. Delayed interinsicoid deflection of right precordial leads.
E.C.G criteria of R.V.H S1Q3 T3 pattern. QR pattern in lead V1 or V3R. An R wave in V1 or V3R. An R/S ratio >1 in V1 or <1 in V5 or V6.
Investigations Help In Diagnosis Chest Radiograph:1. Enlarged pulmonary artery.2. Enlarged right ventricle.3. Distended azygous or other central vein.4. Westermark sign “oligemia of lung lobe or entire lung “.5. Hampton’s hump “wedge shaped opacity6. COPD signs as anterior-posterior diameter , flattening of diaphragm , honeycombing and hyperlucency.
Computed tomography:1. Main pulmonary artery diameter measurements >29 mm have a sensitivity of 84 % and specificity of 75% for the diagnosis of pulmonary hypertension.2. There are data to suggest that an enlarged main pulmonary artery diameter and ratio of segmental pulmonary artery diameter to corresponding bronchus diameter > 1 increases the specificity of a pulmonary hypertension diagnosis.
Echocardiography :1. An adequate examination is reported in up to 65 – 80 % of patients with COPD because of the technical difficulty associated with hyperinflation.2. A better examination can be obtained with transesophageal echocardiography.3. Doppler echocardiography has aided in the assessment of pulmonary artery pressure by measuring the flow of regurgitant blood across the tricuspid valave or by measuring right vetricular ejection flow.
Right heart catheterization :1. This is the gold standard for thorough evaluation and diagnosis of pulmonary hypertension. Radionuclide angiography (gated blood pool scan ):1. This test is most useful for measuring right and left ventricular ejection fraction. Magnetic resonance imaging :1. This non invasive technique yields highly accurate dimensions of the right ventricle.
Oxygen therapy This is considered a mainstay of treatment for patients with COPD . Large controlled trials demonstrate that long term administration of oxygen improves survival in hypoxemic patients with COPD. Oxygen therapy decreases pulmonary vascular resistance by diminishing pulmonary vasoconstriction and improves right ventricular stroke volume and cardiac output .
Phlebotomy In patient with pronounced polycythemia (hematocrit >60 % ), phlebotomy may provide symptomatic relief . In resting patients , phlebotomy can affect a mild decrease in pulmonary artery pressure and pulmonary vascular resistance . In general , blood viscosity has less effect than blood volume on pulmonary arterial pressure . Phlebotomy , with a goal hematocrit of 50 %, may improve exercise tolerance in patients with polycythemic COPD.
Phlebotomy is not an optimal single therapy but can be considered in polycythemic patients with acute decompensation .
Noninvasive positive pressure (ventilation ( NIPPV For patients with acute COPD exacerbations, NIPPV has been shown to improve outcomes in acute hospitalization. No such data exist for long-term treatment of COPD or sleep-disordered breathing with NIPPV. There is evidence that oxygenation is improved in these patients, but reduction in pulmonary artery pressure is only anecdotal.
Diuretics Diuretic therapy with salt restricted diet may be needed in congestive heart failure to take care of the excessive water that the lungs share and to improve alveolar ventilation and gas exchange. However, the use of diuretics may produce hemodynamic adverse effects, such as volume depletion, decrease venous return to the right ventricle, and decreased cardiac output.
Another complication is the production of hypokalemic metabolic alkalosis, which diminishes the Co2 stimulus to the respiratory center, decreasing ventilatory drive.
Anticoagulation Chronic anticoagulation with Warfarin may provide benefit for those patients with Cor Pulmonale resulting from thrombo- occlusive pulmonary disease.
vasodilators Vasodilators improve cardiac output in many patients with cor pulmonale. However, treatment with vasodilators may be associated with adverse effects, including systemic hypotension that coronary perfusion pressure, blunting of hypoxic pulmonary vasoconstriction and circulatory collapse.
Different classes of vasodilators used in Cor Pulmonale Nonspecific vasodilators:1. Hydralazine increases cardiac output in patients with COPD; however, its ability to decrease pulmonary artery pressure is unpredictable.2. Nitroprusside may provide benefit but also runs the risk of systemic hypotension and compromise of adequate coronary perfusion pressure.
3. Calcium channel blockers such as Nifedipine reduce pulmonary vascular resistance and increase cardiac output only for the short term.4. Verapamil and Diltiazem have not proved effective in dilating pulmonary vasculature.
Pulmonary vasodilators :1. Prostaglandins decrease pulmonary artery pressure and increase right ventricular ejection fraction and cardiac output.2. Aerosolized prostacyclin causes pulmonary artery vasodilatation and improves cardiac output and arterial oxyhemoglobin saturation in patients with chronic pulmonary hypertension.
3. Nitric oxide provides a real clinical scenario. It reliably decreases pulmonary vascular resistance without causing systemic hypotension and preserves or improves optimal ventilation-perfusion match. Its drawbacks are difficult administration, high cost, and a well- documented tachyphylactic effect. Multiple studies have shown that its benefits are most significant for only 1-3 days, especially in patients with acute respiratory distress syndrome.
Inotropes with vasodilatory properties :1. Dobutamine is an inotropic agent with vasodilatory effect which improves right ventricular function and cardiac output, but its effect on systemic blood pressure is unpredictable.2. Amrinone lowers pulmonary artery pressure and rises cardiac output and systemic blood pressure.
Endothelin receptor antagonist :1. Bosentan is an endothelin receptor antagonist that produces pulmonary vasodilation and attenuates ventricular remodeling and improve survival on chronic use.
Role of digoxin in treatment Cardiac output improves in about 10% of patients with primary pulmonary hypertension who receive digoxin. This rate is similar to that in patient with left ventricular dyfunction. Patients who receive digoxin also show a modest increase in pulmonary pressure, perhaps due to increase in cardiac output.
Clinical studies show improvement in right ventricular function only in those patients who have reduced left ventricular ejection fraction. Recently, digoxin has fallen out of favor in the setting of left ventricular dysfunction; the trend in clinical medicine has been its continued use in rate control.
KEY POINTS OF COR PULMONALE Right side heart failure is not necessary to make the diagnosis of cor pulmonale. Any process that cause pulmonary hypertension can cause cor pulmonale. COPD is the most common cause of chronic cor pulmonale. Cor pulmonale is common in advanced obstructive lung disease and has a poor 5-year survival rate. Ventricular interdependence can developin late stages of cor pulmonale.