Dilatable prosthesis for banding the main pulmonary artery: human clinical trials

Expandable Valves, Annuloplasty Rings, Shunts, and Bands for Growing Children

In congenital heart surgery, the surgeon must constantly consider how a palliative or corrective procedure could be impacted by the child's somatic growth. Within pediatric valve surgery, existing valve repair techniques lack growth-accommodating prostheses. Valve replacement options are fixed in size and unable to grow with the child, thus subjecting children to repeated valve reoperations. When creating a systemic-to-pulmonary artery shunt, replacing a branch pulmonary artery or conduit, creating an extracardiac Fontan pathway, or banding the pulmonary artery, the implant size must factor in both the child's current size and his or her anticipated growth. A variety of growth-accommodating technologies have been developed to fill this unmet need. Some devices have reached the clinical arena, while several are in preclinical development. The purpose of this review is to characterize the clinical need for growing device technology, and then review established and developing technologies for growth accommodation in congenital heart surgery.

Surgical strategies and novel alternatives for the closure of ventricular septal defects

A variety of therapies are available to close ventricular septal defects (VSDs). These include surgical closure on bypass, percutaneous device closure, as well as perventricular hybrid closure. Due to the incidence of heart block (1-5%) associated with percutaneous device closure of perimembranous VSDs, surgical closure presently remains the gold standard and preferred therapy for these defects. Therapeutic options are more varied for muscular VSDs. Beyond infancy, transcatheter closure offers excellent results with low morbidity and mortality, without the need for cardiopulmonary bypass. Infants however have a higher incidence of adverse events using a percutaneous approach. Large mid-muscular VSDs in infants can be treated successfully using a hybrid approach, surgical closure on bypass or a percutaneous approach. However, VSDs located apically or anteriorly are difficult to identify surgically and for these infants, perventricular hybrid closure should be considered as the preferred therapeutic modality. However, some VSD's also can be closed percutaneously.

Efficacy of intraluminal pulmonary artery banding

OBJECTIVE

The extraluminal technique of pulmonary artery banding can be difficult to perform precisely in conjunction with cardiopulmonary bypass and is associated with a significant risk of band-related complications. We analyzed our results with an intraluminal technique of pulmonary artery banding in patients who required cardiopulmonary bypass for the performance of associated cardiac repairs.

METHODS

The medical records of 18 neonates and infants who underwent intraluminal pulmonary artery banding were retrospectively reviewed. A circular patch with a 3.0-mm, 3.6-mm, or 4.0-mm diameter fenestration was sutured to the inner circumference of the main pulmonary artery. Preoperative, intraoperative, and postoperative variables were reviewed to assess the efficacy and safety of the intraluminal technique.

RESULTS

Intraluminal pulmonary artery banding produced a consistent and significant reduction in the systolic pulmonary artery pressure (64.00 +/- 12.24 to 16.53 +/- 6.33 mm Hg, P < .001), the systolic pulmonary artery pressure/systolic systemic pressure ratio (0.91 +/- 0.10 to 0.19 +/- 0.07, P < .001), and the pulmonary flow/systemic flow ratio (4.32 +/- 3.04 to 0.91 +/- 0.49, P = .015). There were no band-related anatomic complications. Two patients did require percutaneous dilation of the intraluminal pulmonary artery band before debanding to palliate systemic arterial desaturation.

CONCLUSIONS

Intraluminal pulmonary artery banding is an effective palliative procedure that can be used in patients who require cardiopulmonary bypass for the performance of cardiac repairs in addition to placement of the pulmonary artery band.

Remote control of pulmonary blood flow: initial clinical experience

OBJECTIVE

After positive experimental results were obtained with the FloWatch-R-PAB (EndoArt S.A., Lausanne, Switzerland), an implantable device for pulmonary artery banding with telemetric control, it was tested in a prospective, multicenter clinical trial.

METHODS

From June to September 2002, 6 patients with a mean age of 10.6 months (1-31 months) and a mean weight of 6.5 kg (3.5-11 kg) underwent pulmonary artery banding with the implantation of the FloWatch-R-PAB device through median sternotomy (4 patients) or left thoracotomy (2 patients). The diagnoses were the following: univentricular heart (2 patients), complete atrioventricular septal defect (2 patients), ventricular septal defect (1 patient), and multiple ventricular septal defects with double aortic arch (1 patient). The associated procedures were atrioseptostomy with cardiopulmonary bypass (2 patients), closure of patent ductus arteriosus (2 patients), and division of double aortic arch (1 patient).

RESULTS

In a mean follow-up of 7 months (6-9 months), there were no early or late deaths, reoperations, or device-related complications. A mean of 5 regulations per patient (range 2-14) were required to adjust the tightening of the pulmonary artery banding, 50% (15/30) within the first postoperative week, 20% (6/30) during the second week, and 30% (9/30) within 8 months after surgery. In 70% (21/30) of the cases, the regulation was required to further narrow the pulmonary artery, and in 30% (9/30) of the cases, the regulation was required to release the pulmonary artery.

CONCLUSIONS

The initial trial confirmed the adequate functioning of the FloWatch-R-PAB device as telemetrically adjustable pulmonary artery banding. Repeated pulmonary artery banding adjustments, dictated by the clinical need in all patients even weeks after surgery, were accomplished without need for reoperation or invasive procedures. In children requiring pulmonary artery banding, the therapeutic strategies can be expanded by this promising technology. This device should be particularly indicated in patients with transposition of the great arteries requiring left ventricular retraining.