SERIAL REPRODUCIBILITY OF CONDUCTANCE CATHETER VOLUMETRY OF LEFT-VENTRICLE IN CONSCIOUS DOGS

Although the conductance catheter technique has been currently applied to in situ measurement of left ventricular volume, reproducibility of this method has not been examined within the same subject on separate days. Accordingly, serial catheter, volumetries (mean 5 days apart) were performed in 10 normal conscious dog, which were chronically instrumented with the conductance catheter, a micromanometer, and caval cuff occluders. Left ventricular end-systolic pressure-volume relationship was also determined during transient caval occlusion. All hemodynamic variables were compared at the same heart rate. There were no significant changes in blood resistivity (10 +/- 7 OMEGA-cm, 8%) and the parallel conductance of the surrounding tissues (7 +/- 6 ml, 10%). The mean difference was 3 +/- 2 ml (7%) for endiastolic volume and 3 +/- 2 ml (11%) for end-systolic volume. Stroke volume and ejection fraction were also reproducible with mean difference of 2 +/- 1 ml (9%) and 3 +/- 2% (8%) respectively. The end-systolic pressure-volume relationships were nearly superimposable with the slope being 6.05 +/- 1.82 mmHg/ml on day 1 and 6.13 +/- 2.22 mmHg/ml on day 2. The difference averaged 0.63 +/- 0.42 mmHg/ml (11%). These results suggest that highly reproducible volume estimates by conductance catheter offer its feasibility of serial assessment of ventricular performance in vivo.