The use of technetium-99m hexamethylpropylene amine oxime labelled white blood cells to detect subclinical inflammation of the heart after cardiopulmonary bypass in children with congenital heart disease

Ten children (6 boys and 4 girls, aged 1–9 years old) underwent operations with a cardiopulmonary bypass, and the technetium-99m hexamethylpropylene amine oxine (^99mTc-HMPAO) labelled white blood cell (WBC) heart scans were used to detect postoperative leukocyte infiltration in the hearts. The results showed that 80% (/810) of the cases had subclinical inflammation in the hearts (grading of WBC scans score 2), and a positive correlation (R = 0.77) was noted between the severity of the inflammation (grading of the WBC scans) and the duration of the cardiopulmonary bypass in the operations. Another control group (9 boys and 2 girls, aged 2–13 years old) underwent operations without a cardiopulmonary bypass, and subclinical inflammation of hearts was demonstrated in only 1 case (9%) by the ^99mTc-HMPAO labelled WBC scans (grading of WBC scans < score 2) after the operations. There was a significant difference (P < 0.001, by a Wilcoxon rank sum test) based upon the severity of the ischaemic heart damage in the two groups. In our preliminary conclusions, the ^99mTc-HMPAO labelled WBC heart scans may provide non-invasive and directly discernible evidence of subclinical inflammation in the heart due to a transient ischaemic state during a cardiopulmonary bypass, even if the clinical symptoms and signs of carditis are not apparent.Correspondence to: Chia-Hung Kao