What is the cause of pulmonary oedema after acute myocardial infarction? A case study

A patient is described with an acute myocardial infarction (AMI) and pulmonary oedema, necessitating mechanical ventilation, at a mean pulmonary capillary wedge pressure (PCWP) below 13 mmHg. The Ga-67-transferrin pulmonary leak index (PLI), a measure of microvascular permeability, was normal. A study of the course of the PCWP revealed intermittent elevations up to 22 mmHg, owing to intermittent mitral regurgitation. Pulmonary oedema after an AMI can thus be caused by pressure factors, even at sporadic elevations of PCWP, following intermittent, ischaemia-induced dysfunction of the posterior papillary muscle. Conversely, the measurement of a normal Ga-67-PLI may help to diagnose hydrostatic as opposed to permeability pulmonary oedema, if sporadic elevations of the PCWP are not recognised.