Measurement of left-to-right shunts by gated radionuclide angiography: concise communication

Gated cardiac blood-pool scans allow comparison of left- and right-ventricular stroke volume. We have applied these measurements to the quantification of left-to-right shunts (QP/QS) in nine patients with atrial septal defects, one patients with partial anomalous pulmonary venous return, four patients with ventricular septal defects, and two patients with patent ductus arteriosus. None of these patients had combined lesions. QP/QS was measured as the right-ventricular (RV) stroke counts divided by the left-ventricular (LV) stroke counts and as the LV stroke counts divided by the RV stroke counts in patients with RV and LV diastolic volume overload respectively. All patients had also QP/QS measurements by oximetry and first-pass radionuclide angiography. The stroke-count measurements indicated the overloaded ventricle in all patients. QP/QS determined by equilibrium gated studies correlated well with those obtained by oximetry (r = 0.79). Reproducibility of the equilibrium measurements was good. We conclude that gated cardiac blood-pool scans can measure left-to-right shunts and can distinguish between shunts with RV and LV volume overload.