cor pulmonale

Cor pulmonale (Latin cor, heart + New Latin pulmōnāle, of the lungs) or pulmonary heart disease is a change in structure and function of the right ventricle of the heart as a result of a respiratory disorder. Right ventricular hypertrophy (RVH) is the predominant change in chronic cor pulmonale, whereas in acute cases, dilation dominates. Both hypertrophy and dilation are the result of increased right ventricular pressure.

Dilation is essentially a stretching of the ventricle, the immediate result of increasing the pressure in an elastic container. Ventricular hypertrophy is an adaptive response to a long-term increase in pressure. Individual muscle cells grow larger and undergo characteristic morphologic changes to allow for the increased contractile force required to move the blood against greater resistance.

To be classified as cor pulmonale, the cause must originate in the pulmonary circulation system. Two major causes are vascular changes as a result of tissue damage (e.g. disease, hypoxic injury, chemical agents, etc.), and chronic hypoxic pulmonary vasoconstriction. RVH due to a systemic defect is not classified as cor pulmonale.

Left untreated, cor pulmonale can lead to right-heart failure and death.

Pathophysiology

There are several mechanisms leading to pulmonary hypertension and cor pulmonale:

• Pulmonary vasoconstriction
• Anatomic changes in vascularization
• Increased blood viscosity
• Idiopathic or primary pulmonary hypertension

Causes

• Acute:
  • Massive pulmonary embolization
  • Exacerbation of chronic cor pulmonale
• Chronic:
  • COPD
  • Increased pulmonary bloodpressure due to left ventricle insufficiency (Backward failure)
  • Loss of lung tissue following trauma or surgery
  • Pierre Robin sequence
  • End stage Pneumoconiosis
  • Sarcoidosis
  • T1-4 Vertebral subluxation
  • Obstructive sleep apnea
  • Sickle cell anemia
  • Bronchopulmonary dysplasia (in infants)

Complications

Blood backs up into the systemic venous system, including the hepatic vein. Chronic congestion in the centrilobular region of the liver leads to hypoxia and fatty changes of more peripheral hepatocytes, leading to what is known as nutmeg liver.

Investigations

• Chest X-Ray - Right ventricular hypertrophy, right atrial dilatation, prominent pulmonary artery, peripheral lung fields show reduced vascular markings
• ECG - Right ventricular hypertrophy - right axis deviation, prominent R wave in lead V1 & inverted T waves in right precordial leads
• Echocardiogram - Right ventricular dilatation and tricuspid regurgitation is likely

Treatment

Elimination of the cause is the most important intervention. Diuretics for RVF, In pulmonary embolism, thrombolysis (enzymatic dissolution of the blood clot) is advocated by some authorities if there is dysfunction of the right ventricle, and is otherwise treated with anticoagulants. In COPD, long-term oxygen therapy may improve cor pulmonale.

Cor pulmonale may lead to congestive heart failure (CHF), with worsening of respiration due to pulmonary edema, swelling of the legs due to peripheral edema and painful congestive hepatomegaly (enlargement of the liver due to tissue damage as explained in the Complications section. This situation requires diuretics (to decrease strain on the heart), sometimes nitrates (to improve blood flow), phosphodiesterase inhibitors such as sildenafil or tadalafil and occasionally inotropes (to improve heart contractility). CHF is a negative prognostic indicator in cor pulmonale.

External links

• Emedicine
• The Merck Manual of Diagnosis and Therapy: Cor Pulmonale