Haemodynamic response to slow plasma volume expansion in uncomplicated myocardial infarction.

Left ventricular performance in 16 patients with uncomplicated acute myocardial infarction (AMI) has been estimated, by measuring the haemodynamic response to a moderate increase in left ventricular filling pressure (LVFP), obtained by an espansion in blood volume with a slow infusion of 250 ml of plasma. In 9 cases the infusion was repeated. This represents a total of 25 tests. In 17 tests (group A) cardiac index (CI) and left ventricular stroke work index (LVSWI) did not increase significantly and sometimes decreased. In 8 tests (group B) The same plasma volume expansion (PVE) induced a moderate but significant increase in CI(p less than 0.001) and LVSWI (p less than 0.001). A higher incidence of inferior wall infarction was present in group B. Control CI and LVFP did not differ between the two groups and there was no correlation between the initial LVFP and the type of response to PVE. For the same volume load, the increase in pulmonary capillary wedge pressure (CWP) showed large individual variations (+1 to +8 mm Hg). As a general rule when CI improved, the increment in CWP was minimal (+1 mm Hg). It is concluded that there is no unique optimal LVFP and that PVE must be carefully monitored, in all cases.