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Definition

Cor pulmonale, often referred to as pulmonary heart disease, is defined as dilat ion and hypertrophy of the right ventricle (RV) in response to

diseases of the pulmonary vasculature and/or lung parenchyma. Historically, this definition has excluded congenital heart disease and those

diseases in which the right heart fails secondary to dysfunction of the left side of the heart.

Etiology and Epidemiology

Cor pulmonale develops in response to acute or chronic changes in the pulmonary vasculature and/or the lung parenchyma that are sufficient to

cause pulmonary hypertension. The true prevalence of cor pulmonale is difficult to ascertain for two reasons. First, not all cases of chronic lung

disease will develop cor pulmonale, and second, our ability to diagnose pulmonary hypertension and cor pulmonale by routine physical

examination and laboratory testing is relat ively insensitive. However, recent advances in 2-D echo/Doppler imaging and biomakers (BNP) make

it easier to screen for and detect cor pulmonale.

Once patients with chronic pulmonary or pulmonary vascular disease develop cor pulmonale, their prognosis worsens. Although chronic

obstructive pulmonary disease (COPD) and chronic bronchitis are responsible for approximately 50% percent of the cases of cor pulmonale in

North America (Chap. 254), any disease that affects the pulmonary vasculature (Chap. 244) or parenchyma can lead to cor pulmonale. Table 227-

6 provides a list of common diseases that may lead to cor pulmonale. In contrast to COPD, the elevation in pulmonary artery pressure appears to

be substantially higher in the interstitial lung diseases (Chap. 255), in which there is an inverse correlation between pulmonary artery pressure

and the diffusion capacity for carbon monoxide, as well as patient survival. Sleep-disordered breathing, once thought to be a major mechanism

for cor pulmonale, is rarely the sole cause of pulmonary hypertension and RV failure. The combination of COPD and associated daytime

hypoxemia is required to cause sustained pulmonary hypertension in obstructive sleep apnea (Chap. 259).

Table 227-6 Etiology of Chronic Cor Pulmonale

Diseases Leading to Hypoxic Vasoconstriction

Chronic bronchitis

Chronic obstructive pulmonary disease

Cystic fibrosis

Chronic hypoventilation

Obesity

Neuromuscular disease

Chest wall dysfunction

Living at high altitudes

Diseases That Cause Occlusion of the Pulmonary Vascular Bed

Recurrent pulmonary thromboembolism

Primary pulmonary hypertension

Venocclusive disease

Collagen vascular disease

Drug induced lung disease

Diseases That Lead to Parenchymal Disease

Chronic bronchitis

Chronic obstructive pulmonary disease

Bronchiectasis

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Cystic fibrosis

Pneumoconiosis

Sarcoid

Idiopathic pulmonary fibrosis

Pathophysiology and Basic Mechanisms

Although many conditions can lead to cor pulmonale, the common pathophysiologic mechanism in each case is pulmonary hypertension that is

sufficient to lead to RV dilation, with or without the development of concomitant RV hypertrophy. The systemic consequences of cor pulmonale

relate to alterations in cardiac output as well as salt and water homeostasis. Anatomically, the RV is a thin walled, compliant chamber that is

better suited to handle volume overload than pressure overload. Thus, the sustained pressure overload imposed by pulmonary hypertension and

increased pulmonary vascular resistance eventually causes the RV to fail.

The response of the RV to pulmonary hypertension depends on the acuteness and severity of the pressure overload. Acute cor pulmonale occurs

after a sudden and severe st imulus (e.g., massive pulmonary embolus), with RV dilatation and failure but no RV hypertrophy (Chap. 256).

Chronic cor pulmonale, however, is associated with a more slowly evolving and slowly progressive pulmonary hypertension that leads to RV

dilation and hypertrophy. The severity of the pulmonary artery hypertension and the onset of RV failure are influenced by multiple factors that

occur intermittently, including hypoxia secondary to alterations in gas exchange, hypercapnia, and acidosis, as well as alterations in RV volume

overload that are affected by exercise, heart rate, polycythemia, or increased salt and retention because of a fall in cardiac output (Fig. 227-2).

The most common mechanisms that lead to pulmonary hypertension, including vasoconstriction, activation of the clott ing cascade, andobliteration of pulmonary arterial vessels, are discussed in Chap. 244.

Clinical Manifestations

Symptoms

The symptoms of chronic cor pulmonale are generally related to the underlying pulmonary disorder. Dyspnea, the most common symptom, is

usually the result of the increased work of breathing secondary to changes in elastic recoil of the lung (fibrosing lung diseases) or altered

respiratory mechanics (e.g., overinflation with COPD), both of which may be aggravated by increased hypoxic respiratory drive. The hypoxia

that occurs in lung disease is the result of reduced capillary membrane permeability, ventilation-perfusion mismatch, and occasionally

intracardiac or intrapulmonary shunting.

Orthopnea and paroxysmal nocturnal dyspnea are rarely symptoms of isolated right HF. However, when present, these symptoms usually reflect

the increased work of breathing in the supine position that results from compromised excursion of the diaphragm. Tussive or effort-related

syncope may occur in patients with cor pulmonale with severe pulmonary hypertension because of the inability of the RV to deliver blood

adequately to the left side of the heart. The abdominal pain and ascites that occur with cor pulmonale are similar to the right heart failure that

ensues in chronic HF. Lower-extremity edema may occur secondary to neurohormonal activation, elevated RV filling pressures, or increased

levels of carbon dioxide and hypoxia, which can lead to peripheral vasodilation and edema formation. The symptoms of acute cor pulmonale with

pulmonary embolus are reviewed in Chap. 256.

Signs

Many of the signs that are encountered in cor pulmonale are also present in HF patients with a depressed EF, including tachypnea, elevated

jugular venous pressures, hepatomegaly, and lower-extremity edema. Patients may have prominent v waves in the jugular venous pulse as a result

of tricuspid regurgitation. Other cardiovascular signs include an RV heave palpable along the left sternal border or in the epigastrium. A systolic

pulmonary ejection click may be audible to the left of the upper sternum. The increase in intensity of the holosystolic murmur of tricuspid

regurgitation with inspiration ("Carvallo's sign") may be eventually lost as RV failure worsens. Cyanosis is a late finding in cor pulmonale and is

secondary to a low cardiac output with systemic vasoconstriction and ventilation-perfusion mismatches in the lung.

Diagnosis

The most common cause of right heart failure is not pulmonary parenchymal or vascular disease, but left heart failure. Therefore it is important to

evaluate the patient for LV systolic and diastolic dysfunction. The ECG in severe pulmonary hypertension shows P pulmonale, right axis

deviation, and RV hypertrophy. Radiographic examination of the chest may show enlargement of the main pulmonary artery, hilar vessels, and

the descending right pulmonary artery. Spiral CT scans of the chest are useful in diagnosing acute thromboembolic disease; however, the

ventilation-perfusion lung scan remains reliable in most centers for establishing the diagnosis of chronic thromboembolic disease (Chap. 256). A

high-resolution CT scan of the chest is the most accurate means of diagnosing emphysema and interstitial lung disease.

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Two-dimensional echocardiography is useful for measuring RV thickness and chamber dimensions as well as the anatomy of the pulmonary and

tricuspid valves. The interventricular septum may move paradoxically during systole in the presence of pulmonary hypertension. As noted,

Doppler echocardiography can be used to assess pulmonary artery pressures. MRI is also useful for assessing RV structure and function,

particularly in patients who are difficult to image with 2-D echocardiography because of severe lung disease. Right-heart catheterization is useful

for confirming the diagnosis of pulmonary hypertension and for excluding elevated left-heart pressures (measured as the PCWP) as a cause for

right heart failure. BNP and N-terminal BNP levels are elevated in patients with cor pulmonale secondary to RV stretch and may be dramatically

elevated in acute pulmonary embolism.

Cor Pulmonale: Treatment

The primary treatment goal of cor pulmonale is to target the underlying pulmonary disease, since this will lead to a decrease in pulmonary

vascular resistance and relieve the pressure overload on the RV. Most pulmonary diseases that lead to chronic cor pulmonale are far advanced

and are, therefore, less amenable to treatment. General principles of treatment include decreasing the work of breathing using noninvasive

mechanical ventilation, bronchodilation, and steroids, as well as treating any underlying infection (Chaps. 254, 255). Adequate oxygenation

(oxygen saturation 9092%) will also decrease pulmonary vascular resistance and reduce the demands on the RV. Patients should be transfused if

they are anemic, and a phlebotomy should be performed to reduce pulmonary artery pressure if the hematocrit exceeds 65%.

Diuretics are effective in the treatment of RV failure, and the indications for their use are similar to those for chronic HF. One caveat of chronic

diuretic use is that they may lead to contraction alkalosis and worsening hypercapnea. Digoxin is of uncertain benefit in the treatment of cor

pulmonale and may lead to arrhythmias in the setting of tissue hypoxia and acidosis. Therefore, if digoxin is administered, it should be given at

low doses and monitored carefully. The treatment of the acute cor pulmonale that occurs with pulmonary embolus is described in Chap. 256. The

treatment of pulmonary hypertension is discussed in Chap. 244.

Further Readings

Ashrafian H et al: Metabolic mechanisms in heart failure. Circulation 116:434, 2007 [PMID: 17646594]

Bardy GH et al: Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med 352:225, 2005 [PMID:

15659722]

Chapman HA: Disorders of lung matrix remodeling. J Clin Invest 113:148, 2004 [PMID: 14722604]

Cleland JG et al: The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med 352:1539, 2005 [PMID:

15753115]

Friedrich EB, Bohm M: Management of end stage heart failure. Heart 93:626, 2007 [PMID: 17435073]

Kessler R et al: "Natural history" of pulmonary hypertension in a series of 131 patients with chronic obstructive lung disease. Am J Respir Crit

Care Med 164:219, 2001 [PMID: 11463591]

Mann DL, Bristow MR: Mechanisms and models in heart failure: The biomechanical model and beyond. Circulation 111:2837, 2005 [PMID:

15927992]

Mazhari R, Hare JM: Advances in cell-based therapy for structural heart disease. Prog Cardiovasc Dis 49:387, 2007 [PMID: 17498519]

Mosterd A, Hoes AW: Clinical epidemiology of heart failure. Heart 93:1137, 2007 [PMID: 17699180]

Pengo V et al: Incidence of chronic thromboembolic pulmonary hypertension after pulmonary embolism. N Engl J Med 350:2257, 2004 [PMID:

15163775]

Bibliography

Crawford JH et al: Hypoxia, red blood cells, and nitrite regulate NO-dependent hypoxic vasodilation. Blood 107:566, 2006 [PMID: 16195332]

Redfield MM et al: Age- and gender-related ventricular-vascular stiffening: A community-based study. Circulation 112:2254, 2005 [PMID:

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