Factor analysis of gated cardiac blood-pool data: application to patients with congenital heart disease.

Ventricular emptying was evaluated in patients with congenital heart disease (CHD) with left-to-right (L-R) shunt by factor analysis of gated equilibrium radionuclide angiography. In 36 (95%) of 38 ventricular septal defect patients and 20 (95%) of 21 atrial septal defect patients with small L-R shunt (pulmonary to systemic blood flow, Qp/Qs less than or equal to 2.5), as well as all patent ductus arteriosus patients, two significant cardiac factors corresponding to the ventricles (ventricular factor) and the atria plus large vessels (atrial factor) were extracted. However, in all of nine ventricular septal defect patients with large L-R shunt (Qp/Qs greater than 2.5), two different ventricular factors were determined which corresponded to the right and left ventricles (RV and LV). The RV factor showed a delay of ejection phase compared with the LV factor, and the delay was correlated with the value of Qp/Qs (r = 0.82, P less than 0.01). In eight (80%) of 10 ASD patients with large L-R shunt (Qp/Qs greater than 2.5), RV was described by the two different ventricular factors located in the septal and free-wall regions. The LV was extracted in the same factor as that located in the septal region of RV. This study demonstrates the capability of factor analysis in the pathophysiological investigation of CDH with L-R shunt.