Cor pulmonale

Cor pulmonale
Classification and external resources
ICD-10	I26, I27
ICD-9	415.0
MeSH	D011660

Cor pulmonale (Latin cor, heart + New Latin pulmōnāle, of the lungs) or pulmonary heart disease is enlargement of the right ventricle of the heart as a response to increased resistance or high blood pressure in the lungs (pulmonary hypertension).

Chronic cor pulmonale usually results in right ventricular hypertrophy (RVH), whereas acute cor pulmonale usually results in dilatation.

Hypertrophy is an adaptive response to a long-term increase in pressure. Individual muscle cells grow larger(in thickness) and change to drive the increased contractile force required to move the blood against greater resistance.

Dilatation is a stretching (in length) of the ventricle in response to acute increased pressure.

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.

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

Overview

The heart and lung are intricately related. Whenever the heart is affected by disease, the lungs will follow and vice versa. Pulmonary heart disease is by definition a condition when the lungs cause the heart to fail.^[1]

The heart has two pumping chambers. The left ventricle pumps blood throughout the body. The right ventricle pumps blood to the lungs where it is oxygenated and returned to the left heart for distribution. In normal circumstances, the right heart pumps blood into the lungs without any resistance. The lungs usually have minimal pressure and the right heart easily pumps blood through.^[2]

However when there is lung disease present, like emphysema, chronic obstructive lung disease (COPD) or pulmonary hypertension- the small blood vessels become very stiff and rigid. The right ventricle is no longer able to push blood into the lungs and eventually fails. This is known as pulmonary heart disease. Pulmonary heart disease is also known as right heart failure or cor pulmonale. The chief cause of right heart failure is the increase in blood pressure in the lungs (pulmonary artery).

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
  • Primary Pulmonary Hypertension
  • Recurrent Pulmonary Embolism
  • Loss of lung tissue following trauma or surgery
  • Pierre Robin sequence
  • End stage Pneumoconiosis
  • Sarcoidosis
  • T1-4 Vertebral subluxation
  • Obstructive sleep apnea
  • Altitude sickness
  • Sickle cell anemia
  • Bronchopulmonary dysplasia (in infants)

Symptoms

The symptoms of pulmonary heart disease depend on the stage of the disorder. In the early stages, one may have no symptoms but as pulmonary heart disease progresses, most individuals will develop the symptoms like:

• Shortness of breath which occurs on exertion but when severe can occur at rest
• Wheezing
• Chronic wet cough
• Swelling of the abdomen with fluid (ascites)
• Swelling of the ankles and feet (pedal edema)
• Enlargement or prominent neck and facial veins
• Enlargement of the liver
• Bluish discoloration of face
• Presence of abnormal heart sounds
• possible bi-phasic atrial response shown on an EKG due to hypertrophy

Diagnosis

In many cases, the diagnosis of pulmonary heart disease is not easy as both the lung and heart disease can produce similar symptoms. Most patients undergo an ECG, chest X ray, echocardiogram, CT scan of the chest and a cardiac catheterization. During a cardiac catheterization, a small flexible tube is inserted from the groin and under x ray guidance images of the heart are obtained. Moreover the technique allows measurement of pressures in the lung and heart which provide a clue to the diagnosis.^[1]

Epidemiology

Each year there are about 20,000 deaths and close to 280,000 hospital admissions among individuals who have pulmonary heart disease. The majority of individuals affected by pulmonary heart disease are women less than 65 years of age. Infants who are born with congenital heart disorders (esp. holes in the heart like a VSD) are prone to pulmonary artery disease. In infants the earlier the heart disease is treated, the better the prognosis.^[3] While pulmonary heart disease is serious, it is much less common than coronary artery disease.^[2]

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. Patients of chronic obstructive pulmonary disease show features of hyperinflation which include widened intercostal space, increased translucency of lung and flattened diaphragm.
• ECG - Right ventricular hypertrophy - right axis deviation, prominent R wave in lead V1 & inverted T waves in right precordial leads, Large S in Lead I, II and III; Large Q in lead III, Tall Peaked P waves (P pulmonale) in lead II, III and aVF. All the above features are not found in a single patient but different patients show different combination of these findings.
• Echocardiogram - Right ventricular dilatation and tricuspid regurgitation is likely

Treatment

Elimination of the cause is the most important intervention. Smoking must be stopped, exposure to dust, flames, household smoke and to cold weather is avoided. If there is evidence of respiratory infection, it should be treated with appropriate antibiotics after culture and sensitivity. 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.

Oxygen is often required to resolve the shortness of breath. Plus, oxygen to the lungs also helps relax the blood vessels and eases right heart failure. Oxygen is given at the rate of 2 litres per minute. Excess oxygen can be harmful to patients because hypoxia is the main stimulus to respiration. If such hypoxia is suddenly corrected by overflow of oxygen, such stimulus to the respiratory center is suddenly withdrawn and respiratory arrest occurs. When wheezing is present, majority of the patients require bronchodilators. A variety of drugs have been developed to relax the blood vessels in the lung. Calcium channel blockers are used but only work in a few cases. Other novel medications that need to be inhaled or given intravenously include prostacyclin derivatives.

Cases of COPD with chronic corpulmonale present with secondary polycythemia , if severe it may increase the blood viscosity and contribute to pulmonary hypertension. If hematocrit(PCV) is above 60%, then it is better to reduce the red blood cell count by phlebotomies.

Mucolytic agents like bromhexine and carbocisteine help bring out excessive bronchial secretions more easily by coughing.

All patients with pulmonary heart disease are maintained on blood thinning medications to prevent formation of blood clots.

When medical therapy fails, one may require a transplant. However, since the lungs are damaged, both the heart and lungs needs to be transplanted. With a shortage of donors this therapy is only done 10-15 times a year in North America.

Prevention

While not all lung diseases can be prevented one can reduce the risk of lung disease. This means avoiding or discontinuing smoking. Patients with end stage emphysema or chronic obstructive lung disease always end up with right heart failure. When working in environments where there are chemicals, wear masks to prevent inhalation of dust particles.^[4]

Footnotes

1. ^ ^{a b} American Medical Network - Pulmonary Heart Disease, Retrieved on 2010-01-25.
2. ^ ^{a b} Pulmonary Heart Disease Information, Retrieved on 2010-01-25.
3. ^ VirtualMedicalCentre.com, Retrieved on 2010-01-25.
4. ^ Living With Pulmonary Heart Disease, Retrieved on 2010-01-25.

External links

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