An approach to cardiac malposition and the heterotaxy syndrome using 99mTc sulfur colloid imaging.

A diagnostic approach to cardiac malposition and the heterotaxy syndrome is outlined. The 99mTc sulfur colloid intravenous forward angiocardiogram and plain chest radiograph are used to determine the two key diagnostic points: position of the venous atrium and stomach. If located on the opposite sides of the body, four basic situs configurations are possible, and the presence of associated cardiac anomalies may be predicted. For the two configurations in which the cardiac apex is on the same side as the stomach, the incidence of associated cardiac anomalies is low; when on opposite sides, the indicence is high. If the venous atrium and stomach are on the same side, then abdominal heterotaxy with associated splenic abnormality is present. Dynamic 99mTc sulfur colloid imaging will usually show interruption of the inferior vena cava, if present, and multiple or absent spleens.