Cor Pulmonale, Emergency Medicine

Basics

Description

Right ventricular hypertrophy (RVH) or dilation caused by elevated pulmonary artery pressure. RVH due to a systemic defect or congenital heart disease is not classified as cor pulmonale.

Acute cor pulmonale:
- Right ventricle is dilated and muscle wall stretched thin
- Overload due to acute pulmonary hypertension (HTN)
- Most often caused by massive pulmonary embolism
Chronic cor pulmonale:
- RVH with eventual dilation and right-sided heart failure
- Caused by an adaptive response to chronic pulmonary HTN
- Predominately occurs as a result of alveolar hypoxia
The pulmonary circulation is a low-resistance, low-pressure system:
- The pulmonary arteries are thin walled and distensible
- Mean pulmonary arterial pressure is usually 12-15 mm Hg
- Normal left arterial pressure is 6-10 mm Hg
- The resulting pressure difference driving the pulmonary circulation is only 6-9 mm Hg
3 factors affect pulmonary arterial pressure:
- Cardiac output
- Pulmonary venous pressure
- Pulmonary vascular resistance
Pulmonary HTN can arise through a number of mechanisms:
- A marked increase in cardiac output
- Left-to-right shunt secondary to congenital heart disease
- Hypoxia:
  - The most common cause of increased pulmonary vascular resistance
  - Hypoxic pulmonary vasoconstriction is an adaptive vasomotor response to alveolar hypoxia
  - A compensatory rise in pressure is seen in the pulmonary arterial system, so flow is maintained across the pulmonary vascular bed.
- Pulmonary embolus causes a similar change by increasing resistance to pulmonary blood flow
- Dramatic rises in blood viscosity or intrathoracic pressure also impede blood flow
Pulmonary HTN is classified into 5 groups
- Group 1: Pulmonary arterial HTN
- Group 2: Pulmonary HTN owing to left heart disease
  - RV dysfunction in this category is not considered cor pulmonale
- Group 3: Pulmonary HTN owing to lung diseases and/or hypoxia
- Group 4: Chronic thromboembolic pulmonary HTN
- Group 5: Pulmonary HTN with unclear multifactorial mechanisms

Epidemiology

Incidence

~86,000 patients die from COPD each yr:
- Associated RV failure is a significant factor in many of these cases, and accounts for 10-30% of heart failure admissions in US.
In patients >50 yr with COPD, 50% develop pulmonary HTN and are at risk of developing cor pulmonale.
The course of cor pulmonale is generally related to the progression of the underlying disease process.
Once cor pulmonale develops, patients have a 30% chance of surviving 5 yr.

Etiology

Chronic hypoxia
- COPD
- High-altitude dwellers
- Sleep apnea
- Chest deformities
  - Kyphoscoliosis
Pulmonary embolism
Interstitial lung disease
- Scleroderma
- Systemic lupus erythematosus
- Mixed connective tissue disease
- Sarcoidosis
- Pulmonary Langerhans cell histiocytosis
- Neurofibromatosis type
- Lymphangioleiomyomatosis
Cystic fibrosis
Severe anemia
Obesity
Pulmonary veno-occlusive disease
Pulmonary vascular obstruction secondary to tumors or adenopathy
Increased blood viscosity:
- Polycythemia vera
- Leukemia
Increased intrathoracic pressure:
- Mechanical ventilation with positive end-expiratory pressure
Idiopathic primary pulmonary HTN

Diagnosis

Signs and Symptoms

Exertional dyspnea
Easy fatigability
Weakness
Exertional syncope
Cough
Hemoptysis
Exertional angina even in the absence of coronary disease
Anorexia
Right upper quadrant discomfort
Wheezing
Hoarseness
Weight gain
Hepatomegaly
Ascites
Peripheral edema

End-stage cor pulmonale

Cardiogenic shock
Oliguria
Cool extremities
Pulmonary edema secondary to intraventricular septum impairing left ventricular diastolic function

History

Exercise intolerance
Palpitations
Chest pain
Lightheadedness
Syncope
Swelling of the lower extremities

Physical Exam

Jugular venous distention:
- Prominent A- and V-waves
Increase in chest diameter
Crackles and/or wheezes
Left parasternal heave on cardiac palpation
Splitting of the 2nd heart sound or murmurs of the pulmonary vasculature may be heard.
Hepatojugular reflex and pulsatile liver
Pitting edema of the lower extremities

Diagnosis Tests & Interpretation

Lab

Pulse oximetry or ABG:
- Resting PO2 40-60 mm Hg
- Resting PCO2 often 40-70 mm Hg
Hematocrit:
- Frequently elevated
B-natriuretic peptide:
- When elevated, is sensitive for moderate to severe pulmonary HTN, and may be an independent predictor of mortality
- Elevated level alone is not enough to establish diagnosis of cor pulmonale.
Other lab tests are not generally useful.

Imaging

CXR:
- Signs of pulmonary HTN:
  - Large pulmonary arteries (>16-18 mm)
  - An enlarged RV silhouette
  - Shows abnormalities in >90% of patients in the detection of cor pulmonale, but does not indicate the severity of disease
  - Pleural effusions do not occur in the setting of cor pulmonale alone.
EKG:
- Right-axis deviation
- Right bundle branch block
- RVH
  - Dominant R-wave in V1 and V2
  - Prominent S-wave in V5 and V6
  - Small R-waves and deep S-waves across the precordium
- Right atrial enlargement
  - Tall, peaked P-waves (P pulmonale)
- S1Q3 pattern with acute cor pulmonale
- Transient changes due to hypoxia
- Right precordial T-wave flattening
Echocardiography
- The noninvasive diagnostic method of choice
- RV dilation or RVH
- Assessment of tricuspid regurgitation
- Doppler quantization of pulmonary artery pressure, RV ejection fraction
Chest CT, ventilation/perfusion scans, or pulmonary angiography:
- Useful in the setting of acute cor pulmonale
Magnetic resonance imaging
- Superior to echocardiography for assessment of right ventricular size and function
Pulmonary function tests
- Impaired diffusion capacity due to pulmonary HTN
Right-heart catheterization:
- The most precise estimate of pulmonary vascular hemodynamics
- Gives accurate measurements of pulmonary arterial pressure and pulmonary capillary wedge pressure

Differential Diagnosis

Primary disease of the left side of the heart
- Mitral stenosis
Congenital heart disease
- Eisenmenger syndrome
  - Left to right shunt caused by a congenital heart defect in the fetal heart causes increased flow through the pulmonary vasculature, causing pulmonary HTN
Hypothyroidism
Cirrhosis

Treatment

Pre-Hospital

Supportive therapy:
- Supplemental oxygen
  - To an endpoint of 90% arterial saturation
- IV access
- Cardiac monitoring
- Pulse oximetry
Treat bronchospasm from associated respiratory disease:
- β-Agonist nebulizers
Caution:
- Vasodilators and diuretics do not have a role in the field.
- Severely hypoxic patients may require endotracheal intubation.

Initial Stabilization/Therapy

ED therapy is directed at the underlying disease process and reducing pulmonary HTN.

Ed Treatment/Procedures

Supplemental oxygen sufficient to raise arterial saturation to 90%:
- Improving oxygenation reduces pulmonary arterial vasoconstriction and RV afterload.
- The improved cardiac output enhances diuresis of excess body water.
- Care must be taken to monitor the patients ventilatory status and PCO2, as hypercapnia may reduce respiratory drive and cause acidosis.
Diuretics, such as furosemide, may be added cautiously to reduce pulmonary artery pressure by contributing to the reduction of circulating blood volume:
- Be wary of volume depletion and hypokalemia
Patients should be maintained on salt and fluid restriction.
There is no role for digoxin in the treatment of cor pulmonale.
Bronchodilators:
- Bronchodilator therapy is particularly helpful for those patients with COPD
- Selective β-adrenergic agents such as terbutaline 0.25 mg SC may be useful.
- Bronchodilator affects and reduces ventricular afterload.
- Theophylline may play a role to improve diaphragmatic contractility and reduce muscle fatigue.
- Anticoagulation may be considered for those at high risk for thromboembolic disease.
Acutely decompensated COPD patients:
- Early steroid therapy
- Antibiotic administration
In general, improvement in the underlying respiratory disease results in improved RV function.

Medication

Furosemide: 20-60 mg IV (peds: 1 mg/kg may increase by 1 mg/kg/q2h not to exceed 6 mg/kg)
Terbutaline: 0.25 mg SC

Follow-Up

Disposition

Admission Criteria

New-onset hypoxia
Anasarca
Severe respiratory failure
Admission criteria for the underlying disease process

Discharge Criteria
Patients without hypoxia or a stable oxygen requirement
Issues for Referral

Close follow-up as long as the underlying etiology has responded to acute management
The need for a sleep study to assess for sleep apnea should be coordinated by the patients physician.

Followup Recommendations

Ensure home oxygenation in patients with chronic hypoxia

Pearls and Pitfalls

The physical exam is unreliable for detecting cor pulmonale in patients with COPD, as hyperinflation of the chest obscures the classic findings.
Vasodilator therapy should only be considered after conventional therapy and oxygenation have failed.

Additional Reading

Benza R, Biederman R, Murali S, et al. Role of cardiac magnetic resonance imaging in the management of patients with pulmonary arterial hypertension. Am Coll Cardiol. 2008;52(21):1683.
Chaouat A, Naeije R, Weitzenblum E. Pulmonary hypertension in COPD. Eur Respir J. 2008;32:1371-1385.
Han MK, McLaughlin VV, Criner CJ, et al. Pulmonary diseases and the heart. Circulation. 2007;116:2992-3005.
Jardin F, Vieillard-Baron A. Acute cor pulmonale. Curr Opin Crit Care. 2009;15:67-70.
Luks AM. Can patients with pulmonary hypertension travel to high altitude? High Alt Med Biol. 2009;10:215-219.

Codes

ICD9

415.0 Acute cor pulmonale
416.9 Chronic pulmonary heart disease, unspecified

ICD10

I26.09 Other pulmonary embolism with acute cor pulmonale
I27.81 Cor pulmonale (chronic)

SNOMED

83291003 Cor pulmonale (disorder)
79955004 Chronic cor pulmonale (disorder)
49584005 Acute cor pulmonale (disorder)

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