aetiology

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Unstable angina is caused by intermittent reduction in oxygen supply to the myocardium, rather than an increase in oxygen demand (1). It is caused by the abrupt, total or sub-total, transient and typically recurrent obstruction of a coronary artery.

  • unstable angina is caused by erosion or rupture of the cap of an atheromatous plaque with superimposition of a platelet-rich thrombus
  • spontaneous fragmentation or lysis of the thrombus, allows resolution of myocardial ischaemia. Howver distal embolism may result in myocardial necrosis - this is reflected in the release of cytosolic proteins (e.g. troponins T and I)
  • a fully developed myocardial infarction with Q waves may occur if there is persistence of an occlusive thrombus

Reference:

  • British Heart Foundation, Factfile 6/2000

Last reviewed 01/2018