Factors affecting hypertrophic scar development in median sternotomy incisions for congenital cardiac surgery

Even after successful operations on children, unattractive postoperative scars are often distressing to patients and their parents. There are no reports about the factors affecting keloid or hypertrophic scar (HS) development after congenital cardiac surgery.

Postoperative scars were studied in 75 patients 3 months after congenital cardiac surgery by median skin incision. The mean age of the 51 males and 24 females was 2.7 +/- 2.3 years (range, 2 days-12 years). The scars were evaluated according to degree of redness, expressed as redness score, and skin blood flow, as measured by laser Doppler imaging. Skin blood flow ratio was calculated as blood flow at the scar divided by blood flow below the navel. After surgery, 40 patients received 5 mg/kg/day of tranilast, which inhibits the collagen synthesis of keloid fibroblasts.

None of the 75 patients had keloid formation and 21 (28%) developed HS after operation. Mean age of patients with HS (HS (+) group) was 4.4 +/- 3.3 years and that of patients with no HS development (HS (-) group) was 1.5 +/- 1.9 years (p < 0.01). There were no significant differences between these two groups in gender or in pre- or postoperative cyanosis. Hypertrophic scar (+) patients exhibited significantly higher skin blood flow ratios than HS (-) patients (2.7 +/- 1.3 versus 1.4 +/- 0.6; p < 0.001). Hypertrophic scar was seen in 11 of 40 tranilast administered patients (28%) and in 10 of 34 patients not receiving tranilast (29%) (NS). Hypertrophic scar was less apparent in the patients who received tranilast versus those who did not; redness scores were 29.5 +/- 16.5 and 51.6 +/- 14.9, respectively (p < 0.01).

These data suggest that age and skin blood flow ratio were the factors affecting HS development. Postoperative use of tranilast did not affect the frequency of HS development but did reduce its redness.