The non-circular shape of FloWatch®-PAB prevents the need for pulmonary
Monday 10th April 2006
Corno, A.F.; Prosi, M.; Fridez, P.; Zunino, P.; Quarteroni, A.;von Segesser, L.K.
Objective: To evaluate the differences between non-circular shape of FloWatch®-PAB and conventional pulmonary artery (PA) banding.Methods: Geometrical analysis. Conventional banding and FloWatch®-PAB perimeters were plotted against cross sections.Computational Fluid Dynamics (CFD) model. CFD compared non-circular FloWatch®-PAB cross sections with conventional banding regarding pressure gradients.Clinical data. Seven children, median age 2months (7days-3years), median weight 4.2kg (3.2-9.8kg) with complex congenital heart defects underwent PA banding with FloWatch®-PAB implantation.Results. Geometrical analysis. Conventional banding: progressive reduction of cross sections was accompanied by progressive reduction of PA perimeters. FloWatch®-PAB: with equal reduction of cross sections the PA perimeter remained constant.CFD model. Non-circular and circular banding provided same trans-banding pressure gradients for same cross sections at any given flow.Clinical data. Mean PA internal diameter at banding was 13.3±4.5mm. After mean interval of 5.9±3.7 months, all children underwent intra-cardiac repair and simple FloWatch®-PAB removal without PA reconstruction. Mean PA internal diameter with FloWatch®-PAB removal increased from 3.0±0.8mm to 12.4±4.5mm (normal mean internal diameter for the age = 9.9±1.6). No residual pressure gradient was recorded in correspondence of the site of the previous FloWatch®-PAB implantation in 6/7 patients, 10mmHg peak and 5mmHg mean gradient in 1/7.Conclusions. The non-circular shape of FloWatch®-PAB can replace conventional circular banding with the following advantages:a)the pressure gradient will remain essentially the same as for conventional circular banding for any given cross section, but with significantly smaller reduction of PA perimeter b)PA reconstruction at the time of de-banding for intra-cardiac repair can be avoided.