Objective: Adjustment of pulmonary blood flow is difficult in pulmonary artery banding for complex congenital heart defects. A new wireless, battery free, telemetrically controlled, implantable device (FloWatch, EndoArt, S.A., Lausanne, Switzerland) allowing for progressive occlusion/reopening of the device through a remote control at the wanted percentage of occlusion (adjustable pulmonary artery banding) underwent experimental evaluation.
Methods: Eleven mini-pigs underwent FloWatch implantation around the main pulmonary artery through left thoracotomy. The first group (n=4), mean age 18.2+/-0.1 weeks, mean body weight 12.0+/-0.1 kg, underwent FloWatch implantation as device tolerance test. The second group (n=7), mean age 8.6+/-3.4 weeks, mean body weight 5.1+/-1.5 kg, underwent functional evaluation: at implantation, 1, 3, 5, 8 and 10 weeks after implantation, the device was progressively occluded and reopened, with Doppler evaluation of the developed pressure gradient.
Results: The four mini-pigs of first group were sacrificed at mean age of 42.3+/-0.1 weeks, mean body weight 25.1+/-3.2 kg (mean interval of 24 weeks after implantation); the device was still functioning and histology revealed almost normal morphology of the pulmonary artery. In all seven mini-pigs of second group the possibility of narrowing/releasing the pulmonary artery was confirmed at implantation and during follow-up: at last control their mean age was 20.5+/-2.8 weeks and the body weight 12.7+/-3.7 kg.
Conclusions: Complete adjustment of pulmonary blood flow is now possible with an implantable device allowing for pulmonary artery banding with early and late telemetric flow control.