Determination of left ventricular volume using a conductance catheter in the diseased human heart

To validate the accuracy of human left ventricular (LV) volume measured by the conductance catheter method, con-ductance volume was compared with LV volume measured by biplane angiography in 19patients with ischaemic heart disease. Angiographic LV volumes were calculated frame by frame and matched with instantaneous conductance vol-umes. Calibration was determined by both gain constant, I/a, and parallel conductance, aVc The gain constant, I/a, was the ratio of stroke volume measured by the thermo dilution method to that measured by the conductance catheter. The parallel conductance, aVc, was estimated by the saline injection method. There was a good correlation between the corrected conductance volume (Vcc) and the angiographic volume (Va^u,) such that V ^ = 0-94 V^^, + 5-3 ml, r = 0-94, P < 0-001. There were no differences in the correlation coefficients between normal and depressed hearts. Compared with the angiographic data, LV end-diastolic volume, end-systolic volume and ejection fraction were deter-mined accurately by the conductance catheter. We conclude that the conductance catheter method, corrected for gain constant and parallel conductance, can accurately and continuously estimate the LV volume throughout the cardiac cycle in the diseased human heart