The significance of radiological changes in the lungs in acute myocardial infarction

Evidence of pulmonary venous hypertension on portable antero-posterior chest radiographs was compared with measurements of the pulmonary artery diastolic pressure on 58 occasions in 26 patients admitted to a coronary care unit with acute myocardial infarction. The pulmonary artery diastolic pressure was assumed to reflect the left ventricular end-diastolic pressure. A normal chest radiograph correctly indicated a pressure below 14 mm Hg except in one patient who had clear clinical and radiological evidence of pulmonary embolism. Signs of pulmonary venous hypertension usually indicated a pulmonary diastolic pressure above 14 mm Hg but were seen with a pressure below this on several occasions. The results suggest that this is due to a time lag between the fall of pressure and radiological improvement, which may have therapeutic significance. One patient had pulmonary oedema with a normal pressure for which no satisfactory explanation is offered.