Cor Pulmonale

Reviewed 06/2017
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Subject: Cor Pulmonale

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BASICS

DESCRIPTION

  • Enlargement and subsequent dysfunction and failure of the right ventricle (RV) in the presence of pulmonary hypertension secondary to abnormalities of the pulmonary system, including disorders of the lung parenchyma, pulmonary circulation, chest wall, and ventilatory mechanisms.

  • For the purposes of this review, pulmonary arterial hypertension (WHO Group I) will not be considered as a cause of cor pulmonale.

  • May occur in acute or chronic setting

    • ▪ Acute: rapid increase of pulmonary arterial pressure resulting in RV overload, dysfunction, and potential cardiovascular collapse
    • ▪ Chronic: progressive hypertrophy and dilation of the RV over months to years, leading to dysfunction, and potentially failure

EPIDEMIOLOGY

  • ∽6-7% of all types of adult heart disease in United States

  • Estimated 10-30% of heart failure admissions in the United States are the result of cor pulmonale, most commonly related to chronic obstructive pulmonary disease (COPD).

Incidence

Difficult to assess: Best estimate is 1/10,000 to 3/10,000/year. 

Prevalence

Difficult to assess: Best estimate is 2/1,000 to 6/1,000. 

ETIOLOGY AND PATHOPHYSIOLOGY

  • Acute: A sudden event, such as large pulmonary embolism (PE), increases resistance to blood flow in the pulmonary vasculature, causing a quick and significant increase of pressure proximally. The RV is unable to overcome this pressure, leading to low RV cardiac output, which ultimately leads to low left ventricle (LV) cardiac output. Increased RV pressures in conjunction with a low cardiac output may cause coronary ischemia, further impairing cardiac output and potentially causing complete cardiovascular collapse.

  • Chronic: A disorder of the pulmonary system causing chronic hypoxia leads to vasoconstriction of the pulmonary vasculature. Over time, the pulmonary vasculature hypertrophies and the intrinsic vasodilatory mechanisms (mediated by nitric oxide) become dysregulated, leading to increases in pulmonary vasculature resistance. The resulting pulmonary hypertension (WHO Group III) transmits increased pressures and volumes to the thin-walled, low-pressure RV, causing maladaptive remodeling (concentric hypertrophy, followed by eccentric dilation frequently with associated tricuspid regurgitation) and subsequent impairment in RV systolic and diastolic function.

  • Pulmonary disorders

    • ▪ Lung parenchymal disease: COPD (most common), interstitial lung disease (ILD)
    • ▪ Pulmonary circulation: thromboembolic disease (associated with pulmonary hypertension WHO Group IV)
    • ▪ Chest wall: severe obesity, kyphoscoliosis
    • ▪ Ventilation: obstructive sleep apnea (OSA) and obesity hypoventilatory syndrome, neuromuscular diseases such as Guillain-Barré syndrome, muscular dystrophy, myasthenia gravis, spinal cord injuries
  • LV failure is not considered a cause of cor pulmonale.

RISK FACTORS

  • Acute cor pulmonale (most commonly caused by PE)

    • ▪ Risk factors associated with PE:
      • * Vessel injury
      • * Stasis
      • * Hypercoagulable states
  • Chronic cor pulmonale (most commonly caused by underlying pulmonary disorder)

    • ▪ Risk factors associated with pulmonary disorders
      • * Tobacco use (COPD)
      • * Occupational exposures (ILD)
      • * Hypercoagulable state (chronic thromboembolic disease)
      • * Obesity, age (chest wall abnormalities)

GENERAL PREVENTION

Management of underlying pulmonary disorder, including aggressive correction of hypoxia and acidosis, which may contribute to worsening pulmonary hypertension. 

COMMONLY ASSOCIATED CONDITIONS

Pulmonary hypertension, defined as the presence of a resting mean pulmonary artery pressure (PAP) >25 mm Hg 

DIAGNOSIS

HISTORY

  • Dyspnea is the most common symptom, although nonspecific; may be present at rest, with exertion, or occur as paroxysmal nocturnal dyspnea

  • Other pulmonary symptoms: pleuritic chest pain, cough, hemoptysis

  • General heart failure symptoms: fatigue, lethargy, syncope; exertional angina less likely

  • Right-sided heart failure symptoms: anorexia, early satiety, right upper quadrant discomfort from hepatic congestion, lower extremity edema

  • Hoarseness secondary to compression of the left recurrent laryngeal nerve by enlarged pulmonary vessels

  • Cardiovascular collapse, shock, and/or cardiac arrest may occur in acute or advanced chronic setting.

PHYSICAL EXAM

  • Peripheral edema is the most common sign of right-sided heart failure, although it is nonspecific.

  • General: pallor, diaphoresis, cyanosis, tachypnea

  • Neck: jugular venous distension, with prominent a-wave

  • Lungs: tachypnea, wheezing

  • Heart

    • ▪ Increased intensity of pulmonic component of second heart sound (P2)
    • ▪ Splitting of S2 over the cardiac apex with inspiration
    • ▪ Audible right-sided S3 or S4
    • ▪ Jugular venous pressure (JVP), with prominent v-wave
    • ▪ RV heave
    • ▪ Pansystolic murmur heard best at right midsternal border increasing with inspiration, consistent with tricuspid regurgitation (typically a late sign)
    • ▪ Early diastolic murmur heard best at left upper sternal border, consistent with pulmonary regurgitation
  • Abdomen: hepatomegaly

  • Extremities: clubbing, bilateral lower extremity edema, also signs of deep vein thrombosis (DVT) such as tenderness or unilateral swelling

DIFFERENTIAL DIAGNOSIS

Other causes of right-sided failure: 
  • Left-sided heart failure (WHO Group II)

  • WHO Groups I and V pulmonary hypertension

  • Right-sided intrinsic cardiomyopathy

DIAGNOSIS TESTS & INTERPRETATION

  • 2D echocardiogram 1[C]

    • ▪ Initial diagnostic test of choice
    • ▪ Elevated PAP
    • ▪ Right ventricular hypertrophy
    • ▪ Bulging of the interventricular septum into the LV with systole
    • ▪ Flattening of the interventricular or interatrial septum
    • ▪ Dilation and hypokinesis of the RV
    • ▪ Tricuspid regurgitation
    • ▪ Dilation of the right atrium
    • ▪ Acute thromboembolic pulmonary disease as evidenced by right ventricular hypokinesis with sparing of the apex (McConnell sign)
    • ▪ Echocardiography can over- or underestimate the PAP depending on image quality or operator. PAP should therefore be verified by catheter.
  • MRI

    • ▪ If echocardiography is inconclusive or as a substitute
    • ▪ Most accurate modality for diagnosing emphysema and ILD
    • ▪ Can assess pressures, size, function, myocardial mass, and viability
    • ▪ Despite being superior to echocardiogram, diagnosis of cor pulmonale still requires assessment via catheterization.
  • Right heart catheterization 1[C]

    • ▪ Gold standard for diagnosis of pulmonary hypertension, and therefore critical for diagnosis of cor pulmonale
    • ▪ Elevated central venous pressure (CVP)
    • ▪ Mean PAP >25 mm Hg at rest
    • ▪ Absence of left heart failure (pulmonary capillary wedge pressure ≪15 mm Hg)

Initial Tests (lab, imaging)

  • CBC may show signs of polycythemia due to chronic hypoxia.

  • Basic metabolic panel (BMP) may demonstrate elevated creatinine secondary to poor cardiac output.

  • Liver function tests (LFTs) may be abnormal due to hepatic congestion or poor cardiac output secondary to RV failure.

  • Brain natriuretic peptide (BNP) and cardiac troponin can be elevated secondary to right ventricular strain.

  • D-dimer may be positive as evidence of underlying thromboembolic pulmonary disease.

  • Arterial blood gas may show hypercapnia due to COPD.

  • ECG often shows signs of right-sided enlargement.

    • ▪ Right axis deviation
    • ▪ An R/S wave ratio >1 in V1
    • ▪ Right ventricular hypertrophy (R wave in V1 and V2 with S waves in V5 and V6)
    • ▪ Right atrial enlargement as evidenced by P pulmonale (increased amplitude of P wave in lead II)
    • ▪ Incomplete or complete right bundle branch block
    • ▪ S1S2S3 pattern or S1Q3T3 inverted pattern
  • Chest x-ray

    • ▪ Cardiomegaly
    • ▪ Enlargement of the central pulmonary arteries and reduced size of peripheral vessels (oligemia)
    • ▪ Reduced retrosternal space due to right ventricular enlargement on lateral views
    • ▪ Enlargement of the right atrium resulting in prominence of the right heart border
    • ▪ Evidence of COPD, ILD, and structural disease (i.e., kyphosis)
    • ▪ Evidence of PE (Westermark sign and Hampton hump)
  • Spiral CT scan of chest

    • ▪ Diagnosis of acute PE
    • ▪ Diagnosis of COPD and ILD
  • Ventilation/perfusion scan (V/Q)

    • ▪ High specificity and sensitivity for acute and chronic thromboembolic disease
    • ▪ May be used for diagnosis of acute thromboembolic disease if contraindication to chest spiral CT
    • ▪ May be preferred to chest spiral CT for diagnosis of chronic thromboembolic pulmonary disease, given higher sensitivity (can detect peripheral pulmonary emboli otherwise missed by spiral CT)
    • ▪ Diagnosis of chronic thromboembolic disease may warrant confirmation by pulmonary angiography.
  • Pulmonary angiography

    • ▪ Gold standard in diagnosis of chronic thromboembolic pulmonary disease
  • Polysomnography

    • ▪ Gold standard for diagnosis of OSA
  • Pulmonary function tests (PFTs)

    • ▪ Impaired diffusion capacity
    • ▪ Obstructive or restrictive ventilatory defects (ILD, structural abnormalities, and COPD)

TREATMENT

Reduce symptoms and improve quality of life and survival. Reduce disease burden via oxygenation, preservation of cardiac function, and attenuation of pulmonary hypertension. 

GENERAL MEASURES

  • Treat underlying disease 2[A].

    • ▪ For underlying pulmonary disease, bronchodilators and/or steroids may be beneficial.
    • ▪ For underlying chronic thromboembolic disease, anticoagulation may be indicated.
  • Supportive therapy as necessary

    • ▪ Continuous positive airway pressure/bilevel positive airway pressure may be used for hypoxia/sleep disorders.
    • ▪ Ventilation using positive-pressure masks, negative-pressure body suits, or mechanical ventilation is suggested for patients with neuromuscular disease.
    • ▪ Phlebotomy may be indicated for severe polycythemia (hematocrit >55%).

MEDICATION

  • Oxygen 3[A]

    • ▪ Long-term continuous oxygen therapy improves the survival of hypoxemic patients with COPD and cor pulmonale.
    • ▪ All patients with pulmonary hypertension whose PaO2 is consistently ≪55 mm Hg or saturation ≤88% at rest, during sleep, or with ambulation should be prescribed oxygen to keep O2 >92 mm Hg.
  • Preservation of cardiac function 4[B]

    • ▪ Inotropes: Dobutamine and milrinone may improve cardiac output; should be reserved for hemodynamically unstable patients
    • ▪ Diuretics: decrease RV filling pressures; also reduces peripheral edema secondary to RHF
      • * Excessive volume depletion should be avoided.
      • * Monitor closely for metabolic alkalosis, as this may suppress ventilatory drive and contribute to hypoxia.
  • Ameliorate pulmonary hypertension 1,4[C]

    • ▪ Treatment of underlying disease is hallmark of management.
    • ▪ When refractory to traditional medical treatment, advanced therapies may be beneficial, although evidence is lacking.
    • ▪ For chronic thromboembolic associated pulmonary hypertension (WHO Group IV), riociguat and macitentan may be used.

ISSUES FOR REFERRAL

Patients with cor pulmonale should be referred to a specialized center for expert consultation. 

SURGERY/OTHER PROCEDURES

  • Endarterectomy for chronic thromboembolic disease (WHO Group IV)

  • Moderate to severe disease refractory to medication may require lung and/or heart transplantation.

ONGOING CARE

DIET

Salt and fluid restriction 

PATIENT EDUCATION

  • Smoking cessation and avoidance of exposure to secondary smoke is strongly recommended.

  • Level of physical activity should be discussed with physician.

  • Pregnancy should be avoided.

PROGNOSIS

  • Patients with cor pulmonale resulting from COPD have a greater likelihood of dying than do similar patients with COPD alone.

  • Pulmonary arterial pressure is a reliable indicator of prognosis; higher pressure is associated with a worse prognosis.

  • In patients with COPD and mild disease (PAP 20 to 35 mm Hg), 5-year survival is 50%.

REFERENCES

Galiè  N, Hoeper  MM, Humbert  M, et al. Guidelines for the diagnosis and treatment of pulmonary hypertension: the Task Force for the Diagnosis and Treatment of Pulmonary Hypertension of the European Society of Cardiology (ESC) and the European Respiratory Society (ERS), endorsed by the International Society of Heart and Lung Transplantation (ISHLT). Eur Heart J.  2009:30(20):2493–2537.  [View Abstract]
McLaughlin  VV, Archer  SL, Badesch  DB, et al. ACCF/AHA 2009 expert consensus document on pulmonary hypertension a report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents and the American Heart Association developed in collaboration with the American College of Chest Physicians; American Thoracic Society, Inc.; and the Pulmonary Hypertension Association. J Am Coll Cardiol.  2009;53(17):1573–1619.  [View Abstract]
Naeije  R. Pulmonary hypertension and right heart failure in chronic obstructive pulmonary disease. Proc Am Thorac Soc.  2005;2(1):20–22.  [View Abstract]
Price  LC, Wort  SJ, Finney  SJ, et al. Pulmonary vascular and right ventricular dysfunction in adult critical care: current and emerging options for management: a systematic literature review. Crit Care.  2010;14(5):R169.  [View Abstract]

SEE ALSO

Chronic Obstructive Pulmonary Disease and Emphysema; Congestive Heart Failure: Differential Diagnosis; Pulmonary Arterial Hypertension; Pulmonary Embolism 

CODES

ICD10

  • I27.81 Cor pulmonale (chronic)

  • I26.09 Other pulmonary embolism with acute cor pulmonale

ICD9

  • 416.9 Chronic pulmonary heart disease, unspecified

  • 415.0 Acute cor pulmonale

SNOMED

  • 83291003 Cor pulmonale (disorder)

  • 49584005 Acute cor pulmonale (disorder)

  • 79955004 Chronic cor pulmonale (disorder)

CLINICAL PEARLS

  • Treatment of cor pulmonale requires treatment of the underlying disease.

  • Continuous, long-term oxygen therapy improves life expectancy and quality of life in cor pulmonale.

  • Referral of patients with cor pulmonale to a specialized center is strongly recommended.

 
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