Aetiology

The basic problem is that pulmonary venous return is "blocked" resulting in increased pulmonary venous pressure. The cause may arise at any point from the pulmonary veins to the systemic circulation.

Causes include:

• anomalous venous drainage - total or partial
• squeezing of the pulmonary veins by the pericardium acting as a purse-string - for example in constrictive pericarditis
• obstruction at the level of the left atrium:
  • mitral stenosis or regurgitation
  • atrial myxoma
  • cor triatriatum
• left ventricular failure
• aortic stenosis or regurgitation
• co-arctation of the aorta