Description

• The term “cor pulmonale” derives from the Latin cor (heart) and pulmonale (lungs). Hence, cor pulmonale is a cardiac complication of primary pulmonary disease.
• Acute or chronic pulmonary processes can lead to increased right-sided cardiac pressures. Resultant pulmonary hypertension (PH) subsequently induces structural alterations and/or impairs right ventricle (RV) function.
• PH is defined by a mean pulmonary artery pressure (mPAP) ≥25 mm Hg at rest measured by right heart catheterization.
• PH may be secondary to abnormalities of the pulmonary system, including disorders of the lung parenchyma, pulmonary circulation, chest wall, and/or ventilatory mechanisms. The pathophysiologic mechanisms of pulmonary arterial hypertension (WHO Group I) and PH secondary to pulmonary processes are biologically and clinically distinct. Therefore, for the purposes of this review, pulmonary arterial hypertension (WHO Group I) will not be considered as a cause of cor pulmonale.
• 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 potential failure

Epidemiology

• ~6–7% of all types of adult heart disease in United States. Globally, the incidence of cor pulmonale is widely variable due to air pollution, tobacco use, and toxic exposure.
• An 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 per 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 proximal to the right ventricular outflow tract. The RV may not be able to generate adequate force to overcome this pressure, leading to low RV cardiac output, which ultimately leads to a decreased 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 leading to chronic hypoxia, which results in progressive vasoconstriction of the pulmonary vasculature. Over time, the pulmonary arterial system hypertrophies and intrinsic vasoactive mechanisms (mediated by nitric oxide, cyclooxygenase, and endothelin) become dysregulated, leading to an increase in pulmonary vasculature resistance. Evidence also supports the involvement of capillary and postcapillary pulmonary vasculature to varying degrees in all PH groups.
• Increased pulmonary vascular resistance yields PH. PH transmits increased pressures and volumes to the thin-walled, low-pressure RV causing maladaptive remodeling (concentric hypertrophy, followed by eccentric dilation), which is frequently associated with tricuspid regurgitation and subsequent impairment in RV systolic and diastolic function.
• Indicators for the presence of PH in these patients may include a disproportionally low diffusing capacity of the lungs for carbon monoxide (DLCO) and an elevated pCO₂.
• Pulmonary disorders
  • Lung parenchymal disease: COPD (most common), interstitial lung disease (ILD), and pulmonary fibrosis
  • Pulmonary circulation: thromboembolic disease (associated with WHO Group IV PH)
  • 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
  • Left ventricular failure is not considered a cause of cor pulmonale.

Risk Factors

• Acute cor pulmonale (most commonly caused by PE)
• 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/ventilatory abnormalities)

General Prevention

Management of underlying pulmonary disorders, including aggressive correction of hypoxia and acidosis, which may contribute to worsening PH

Commonly Associated Conditions

PH, defined as the presence of a resting mPAP >25 mm Hg