Simplified count-based estimates of left ventricular volume.

Accurate count-based radionuclide estimates of left ventricular volume without the use of a blood sample have not been well described. Resting gated blood pool scans were obtained within 24 hours of catheterization in 31 patients (group 1), and simultaneously with thermodilution cardiac outputs in 29 other patients (group 2) at rest and during an induced-volume change (intervention). End-diastolic and end-systolic volumes were calculated from the single-plane angiogram in Group 1 and from the combination of thermodilution stroke volume and radionuclide ejection fraction in group 2. Excellent correlations were noted between scintigraphic counts and angiographic volumes (r = 0.964), between scintigraphic counts and thermodilution-derived volumes (r = 0.979), and between interventional scintigraphic counts and interventional thermodilution-derived volumes (r = 0.941). Thermodilution and scintigraphic volume changes during the intervention were well correlated (r = 0.85). Accurate count based estimates of left ventricular volume without a blood sample are feasible at rest and during an intervention.