Bedside determination of left atrial pressure.

An investigation was conducted to assess the accuracy of left heart filling pressures determined by a right heart catheter introduced at the bedside. Twelve patients were studied after open cardiac surgery by simultaneously recording pressures from both sides of the pulmonary capillary bed with a direct left atrial catheter and a flow-directed pulmonary arterial catheter. The mean pulmonary artery "occluded" pressure was shown to be a highly reliable index of mean left atrial pressure in all cases. It was much more accurate than pulmonary end-diastolic pressure, especially in six patients with pre-existing pulmonary hypertension.