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Cor Pulmonale, Emergency Medicine

Basics

Description

- 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

- 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

- 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)

- Echocardiography - The noninvasive diagnostic method of choice - RV dilation or RVH - Assessment of tricuspid regurgitation - Doppler quantization of pulmonary artery pressure, RV ejection fraction

- Right-heart catheterization: - The most precise estimate of pulmonary vascular hemodynamics - Gives accurate measurements of pulmonary arterial pressure and pulmonary capillary wedge pressure

- Primary disease of the left side of the heart - 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

- IV access - Cardiac monitoring - Pulse oximetry

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 thinOverload due to acute pulmonary hypertension (HTN)Most often caused by massive pulmonary embolism
  • Chronic cor pulmonale:RVH with eventual dilation and right-sided heart failureCaused by an adaptive response to chronic pulmonary HTNPredominately occurs as a result of alveolar hypoxia
  • The pulmonary circulation is a low-resistance, low-pressure system:The pulmonary arteries are thin walled and distensibleMean pulmonary arterial pressure is usually 12-15 mm HgNormal left arterial pressure is 6-10 mm HgThe resulting pressure difference driving the pulmonary circulation is only 6-9 mm Hg
  • 3 factors affect pulmonary arterial pressure:Cardiac outputPulmonary venous pressurePulmonary vascular resistance
  • Pulmonary HTN can arise through a number of mechanisms:A marked increase in cardiac outputLeft-to-right shunt secondary to congenital heart diseaseHypoxia:The most common cause of increased pulmonary vascular resistanceHypoxic pulmonary vasoconstriction is an adaptive vasomotor response to alveolar hypoxiaA 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 flowDramatic rises in blood viscosity or intrathoracic pressure also impede blood flow
  • Pulmonary HTN is classified into 5 groupsGroup 1: Pulmonary arterial HTNGroup 2: Pulmonary HTN owing to left heart diseaseRV dysfunction in this category is not considered cor pulmonaleGroup 3: Pulmonary HTN owing to lung diseases and/or hypoxiaGroup 4: Chronic thromboembolic pulmonary HTNGroup 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 hypoxiaCOPDHigh-altitude dwellersSleep apneaChest deformities
  • Pulmonary embolism
  • Interstitial lung diseaseSclerodermaSystemic lupus erythematosusMixed connective tissue diseaseSarcoidosisPulmonary Langerhans cell histiocytosisNeurofibromatosis typeLymphangioleiomyomatosis
  • Cystic fibrosis
  • Severe anemia
  • Obesity
  • Pulmonary veno-occlusive disease
  • Pulmonary vascular obstruction secondary to tumors or adenopathy
  • Increased blood viscosity:Polycythemia veraLeukemia
  • 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:
  • 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 HgResting PCO2 often 40-70 mm Hg
  • Hematocrit:
  • B-natriuretic peptide:When elevated, is sensitive for moderate to severe pulmonary HTN, and may be an independent predictor of mortalityElevated 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 silhouetteShows abnormalities in >90% of patients in the detection of cor pulmonale, but does not indicate the severity of diseasePleural effusions do not occur in the setting of cor pulmonale alone.
  • EKG:Right-axis deviationRight bundle branch blockRVHDominant R-wave in V1 and V2Prominent S-wave in V5 and V6Small R-waves and deep S-waves across the precordiumRight atrial enlargementTall, peaked P-waves (P pulmonale)S1Q3 pattern with acute cor pulmonaleTransient changes due to hypoxiaRight precordial T-wave flattening
  • EchocardiographyThe noninvasive diagnostic method of choiceRV dilation or RVHAssessment of tricuspid regurgitationDoppler 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 imagingSuperior to echocardiography for assessment of right ventricular size and function
  • Pulmonary function testsImpaired diffusion capacity due to pulmonary HTN
  • Right-heart catheterization:The most precise estimate of pulmonary vascular hemodynamicsGives accurate measurements of pulmonary arterial pressure and pulmonary capillary wedge pressure

Differential Diagnosis

  • Primary disease of the left side of the heart
  • Congenital heart diseaseEisenmenger syndromeLeft 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 oxygenTo an endpoint of 90% arterial saturationIV accessCardiac monitoringPulse oximetry
  • Treat bronchospasm from associated respiratory disease:
  • 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 COPDSelective 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 therapyAntibiotic 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)