Summary:The slope of the end-systolic pressure-volume relationship (L,), which is generated clinically by load manipulation, as well as the "absolute" peak systolic pressure end-systolic volume ratio (denoted as pressurevolume ratio), have been suggested as indices defining left ventricular function. This study represents an attempt to determine the relationship between these two indices by studying 20 patients (16 with coronary artery disease and 4 with normal coronary arteries) undergoing cardiac catheterization. Left ventriculography was performed three times in each patient: (1) in the control baseline state, (2) after rapid intravenous infusion of 250-300 cc of saline, and (3) after sublingual administration of 5 mg isosorbide dinitnte. & was approximated by linear regression using the peak left ventricular pressure (replacing endsystolic pressure) and the smallest left ventricular (endsystolic) volume for these three different loads. Acute ischemia with typical chest pain and ECG changes developed in 4 patients during saline loading. The pressurevolume ratio showed no change with load manipulation in patients who did not demonstrate ischemia. In the 4 Patients who developed acute ischemia, the pressurevolume ratio dropped from 4.4f1.3 to 2.9i-0.9 W g l d (p ~0.001). In d l of the patients, the pressureratio, but not the Em,,, correlated with the ejection fraction (r=0.6; p c 0.05). In addition, the & line demonstmted a markedly nonphysiological Vo. There was no correlation between Em,, and pressure-volume ratio.Generally, there was a significant disparity between & and the peak systolic pressure-volume ratio, with the latter having the advantage of simplicity, sensitivity to acute ischemia, and a correlation with the wellestablished EF index.
