Down Syndrome as a Factor Influencing Hemodynamic Response to Pulmonary Artery Banding

Abstract.

The hemodynamic response to pulmonary artery banding (PAB) in relation to the preoperative pulmonary/systemic vascular resistance (R_p/R_s) ratio and to the timing of surgery, with special regard to Down syndrome, was investigated in 56 nonconsecutive pediatric patients aged 3 days to 6 months (mean 2.5 months) with simple and complex congenital shunt-related cardiac malformations. Among the non-Down patient group (39 patients; mean age 6.9 weeks) there was a good hemodynamic response in all but three cases, irrespective of the preoperative R_p/R_s ratio; these three poor responders had preoperatively normal or nearly normal R_p/R_s ratios (R_p/R_s < 0.3) and were affected postoperatively by lung complications. In the Down patient group (17 patients; mean age 8.2 weeks) the mean preoperative as well as the mean postoperative R_p/R_s ratio was higher than in the non-Down patient group (preoperative R_p/R_s 0.49 versus 0.32; postoperative R_p/R_s 0.31 versus 0.18). There was a good hemodynamic response in all five patients with Down syndrome who had preoperative normal or nearly normal pulmonary vascular resistance ratios (R_p/R_s < 0.3). Among 12 patients with Down syndrome and preoperative increased resistance ratios (R_p/R_s > 0.3) PAB did not cause a reduction in pulmonary vascular resistance (PVR) in five patients (postoperative R_p/R_s 0.49–1.00), all operated on at more than 6 weeks of age. PAB resulted in effective reduction of postoperative R_p/R_s ratios (range 0.10–0.27) in seven patients, six of them younger and one older than 6 weeks at the time of the banding procedure. In conclusion, patients with Down syndrome and shunt-related cardiac malformations (predominantly total atrioventricular canal cases) in general have higher pre- and postoperative R_p/R_s ratios than non-Down children and also have a higher potential for developing pulmonary vascular obstructive disease despite hemodynamically effective PAB. Especially in children with Down syndrome and pathologically high resistance ratios, PAB, if indicated, should be performed as early as possible.