Cor Pulmonale

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 atrial 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 year:
    • Associated RV failure is a significant factor in many of these cases, and accounts for 10–30% of heart failure admissions in the U.S.
  • 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

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