Remote control of pulmonary blood flow: initial clinical experience

Use of Flow Restrictors in Congenital Heart Disease

The surgical pulmonary artery band was first introduced in 1952 and, to this day, can produce challenges in regard to the ideal amount of restriction and the need for reoperations. A transcatheter option may be the ideal solution as it allows for a less-invasive approach for a better hemodynamic assessment and easier re-intervention. To date, multiple approaches have been developed with device modifications to create restrictions to flow, each with advantages and limitations. Continued experience is still necessary to determine the ideal device to use to create an adequate and modifiable level of restriction.

Dilatable Pulmonary Artery Banding Palliation in Congenital Heart Disease

BACKGROUND

Surgical pulmonary artery banding (PAB) has been limited in practice because of later requirement for surgical removal or adjustment. The aim of this study is to describe our experience creating a dilatable PAB via transcatheter balloon dilation (TCBD) in congenital heart disease (CHD) patients.

METHODS

Retrospective chart review of adjustable PAB-outline anatomical variants palliated and patient outcomes.

RESULTS

Sixteen patients underwent dilatable PAB-median age 52 days (range 4-215) and weight 3.12 kg (1.65-5.8). Seven (44%) of the patients were premature, 11 (69%) had ventricular septal defect(s) with pulmonary over-circulation, four (25%) atrioventricular septal defects, and four (25%) single ventricle physiology. Subsequent to the index procedure: five patients have undergone intracardiac complete repair, six patients remain well palliated with no additional intervention, and four single ventricles await their next palliation. One patient died from necrotizing enterocolitis (unrelated to PAB) and one patient required a pericardiocentesis postoperatively. Five patients underwent TCBD of the PAB without complication-Two had one TCBD, two had two TCBD, and another had three TCBD. The median change in saturation was 14% (complete range 6-22) and PAB diameter 1.7 mm (complete range 1.1-5.2). Median time from PAB to most recent outpatient follow-up was 868 days (interquartile range 190-1,079).

CONCLUSIONS

Our institution has standardized a PAB technique that allows for transcatheter incremental increases in pulmonary blood flow over time. This methodology has proven safe and effective enough to supplant other institutional techniques of limiting pulmonary blood flow in most patients-allowing for interval growth or even serving as the definitive palliation.

Potts anastomosis in children with severe pulmonary arterial hypertension and atrial septal defect

Aims

Potts shunt has been proposed as a bridge or alternative to lung transplantation for children with severe and drug‐refractory suprasystemic pulmonary arterial hypertension (PAH). We describe the management of the atrial shunt when a Potts shunt is planned in refractory PAH.

Methods and results

We report a case series of children in whom a Potts shunt was done for severe PAH associated with an atrial septal defect to illustrate the different clinical and haemodynamic scenarios. Five children (2 to 13 years) underwent a Potts shunt: three surgical, one percutaneous Potts shunt, and one percutaneous stenting of a restrictive arterial duct. All had associated atrial septal defect. Those who had generalized cyanosis before the procedure had a complicated postoperative course and required longer ventilatory and inotropic support, except the one who had atrial septal defect closure before the Potts shunt. One of the three cyanotic patients died. Two patients with left‐to‐right shunt before the Potts shunt had an uncomplicated postoperative course.

Conclusions

Shunt physiology is only partially predictable after the Potts shunt in children with PAH and atrial septal defect. Abrupt drop in left ventricle preload while the right ventricle is decompressed can potentially be prevented by atrial septal defect closure prior to the Potts shunt.

Physiological Fontan Procedure

Objective: The conventional Fontan circulation deviates the superior vena cava (SVC = 1/3 of the systemic venous return) toward the right lung (3/5 of total lung volume) and the inferior vena cava (IVC = 2/3 of the systemic venous return) toward the left lung (2/5 of total lung volume). A "physiological" Fontan deviating the SVC toward the left lung and the IVC toward the right lung was compared with the conventional setting by computational fluid dynamics, studying whether this setting achieves a more favorable hemodynamics than the conventional Fontan circulation. Materials and Methods: An in-silico 3D parametric model of the Fontan procedure was developed using idealized vascular geometries with invariant sizes of SVC, IVC, right pulmonary artery (RPA), and left pulmonary artery (LPA), steady inflow velocities at IVC and SVC, and constant equal outflow pressures at RPA and LPA. These parameters were set to perform finite-volume incompressible steady flow simulations, assuming a single-phase, Newtonian, isothermal, laminar blood flow. Numerically converged finite-volume mass and momentum flow balances determined the inlet pressures and the outflow rates. Numerical closed-path integration of energy fluxes across domain boundaries determined the flow energy loss rate through the Fontan circulation. The comparison evaluated: (1) mean IVC pressure; (2) energy loss rate; (3) kinetic energy maximum value throughout the domain volume. Results: The comparison of the physiological vs. conventional Fontan provided these results: (1) mean IVC pressure 13.9 vs. 14.1 mmHg (= 0.2 mmHg reduction); (2) energy loss rate 5.55 vs. 6.61 mW (= 16% reduction); (3) maximum kinetic energy 283 vs. 396 J/m3 (= 29% reduction). Conclusions: A more physiological flow distribution is accompanied by a reduction of mean IVC pressure and by substantial reductions of energy loss rate and of peak kinetic energy. The potential clinical impact of these hemodynamic changes in reducing the incidence and severity of the adverse long-term effects of the Fontan circulation, in particular liver failure and protein-losing enteropathy, still remains to be assessed and will be the subject of future work.

A study on the mortality and complication rates following percutaneously adjustable pulmonary artery banding

Introduction: Pulmonary artery (PA) banding is a procedure associated with high morbidity and mortality rates. It however can effectively palliate several forms of congenital heart lesions with increased pulmonary flow. Occasionally, to obtain an optimal degree of banding following operation, readjustment of the band is inevitable. We describe the technique of adjustable PA banding to prevent this problem.

Methods: From June 2007 to 2008, 21 patients with congenital cardiac abnormalities including Single ventricle (1), transposition of great arteries (TGA) (4) and ventricular septal defect (VSD) (16) were operated via percutaneously adjustable PA banding in Madani Hospital (Tabriz, Iran).

Results: The mean age and the mean weight of the patients were 12±.8 months and 61±.7 kg respectively. Seventeen (81%) patients survived the operation. Cause of death was heart failure in 2 (9.5%) patients, and arrhythmia in 2 (9.5%) patients. Later, patients were followed up for 6 months. Satisfactory band gradient was achieved between 48 and 240 hours. Mean PA gradient before and 1 and 6 months after adjusting was (55.3±7.1 mmHg), (54.7±5.1 mmHg), and (53.2±5.4 mmHg) respectively. In the follow up period, there were 2 deaths, one caused by aspiration pneumonia and one caused by poor mixing. Postoperative complications were observed in 28.5% of the cases including cardiac (10%), pulmonary (pneumothorax, pneumonia) (10%) and infectious complications (9%).

Conclusion: The technique of percutaneously adjustable PA banding is simple and inexpensive and allows easy band adjustments without the need for multiple reoperations. Moreover, our assessment reveals that created gradient is constant and did not decrease with time.

Multiple ventricular septal defects: a new strategy

INTRODUCTION

A multicenter prospective study was conducted to evaluate a new strategy for multiple Ventricular Septal Defects (VSDs).

MATERIALS AND METHODS

From 2004 to 2012 17 consecutive children (3 premature, 14 infants), mean age 3.2 months (9 days-9 months), mean body weight 4.2 kg (3.1-6.1 kg), with multiple VSDs underwent Pulmonary Artery Banding (PAB) with an adjustable FloWatch-PAB(®). Associated cardiac anomalies included patent ductus arteriosus (1), aortic coarctation (2), hypoplastic aortic arch (2), and left isomerism (3). Five patients (5/17 = 29.4%) required pre-operative mechanical ventilation, with a mean duration of 64 days (7-240 days)

RESULTS

There were no early or late deaths during a mean follow-up of 48 months (7-98 months), with either FloWatch removal or last observation as end-points. FloWatch-PAB(®) adjustments were required in all patients: a mean of 4.8 times/patient (2-9) to tighten the PAB, and a mean of 1.1 times/patient (0-3) to release the PAB with the patient's growth. After a mean interval of 29 months (8-69 months) 10/17 (59%) patients underwent re-operation: 7/10 PAB removal, with closure of a remaining unrestrictive VSD in 6 (peri-membranous in 3 patients, mid-muscular in 2, and inlet in 1) and Damus-Kaye-Stansel, bi-directional Glenn, and atrial septectomy in 1; 3/9 patients required only PAB removal. All muscular multiple VSDs had closed in all 10 patients. PA reconstruction was required in 1/10 patient. In 5/7 of the remaining patients with the PAB still in situ, all muscular VSDs had already closed. The only 2 patients with persistent muscular multiple VSDs are the 2 patients with the shortest follow-up.

CONCLUSION

This reproducible new strategy with an adjustable PAB simplifies the management of infants with multiple VSDs and provides the following advantages: (a) good results (0% mortality), delayed surgery with a high incidence (15/17 = 88%) of spontaneous closure of multiple muscular VSDs, and facilitated closure of residual unrestrictive VSD (peri-membranous, mid-muscular, or inlet) at an older age and higher body weight; PAB with FloWatch-PAB(®) and its subsequent removal can potentially be the only procedure required for Swiss cheese multiple VSDs without an associated peri-membranous unrestrictive VSD.

Catheter balloon adjustment of the pulmonary artery band: feasibility and safety

The study aimed to assess the feasibility and safety of increasing pulmonary artery band (PAB) diameter by catheter-based PAB balloon dilation (PABBD). Eight dilations were performed between October 2006 and December 2008. Hemoclips were used to fix PABs surgically in a procedure designed to permit progressive clip dislodgment in a controlled manner. The PABBD resulted in gradual band loosening until the desired physiologic state was achieved. At time of PABBD, the patients had a mean age of 6 months (range 3-14 months) and a mean weight of 5 kg (range 2.6-7.3 kg). The median time from PAB placement until PABBD was 4.5 months (range 1-9 months). The single-balloon technique was used in seven cases (serial dilations in 5 cases) and the double-balloon technique in one case. The PABBDs were successful for all the patients, who experienced a mean saturation increase of 75-89% (P = 0.01) (mean increase of 20%), a mean PAB gradient decrease from 69 to 36 mmHg (P = 0.002) (mean decrease of 49%), and a mean band site diameter increase from 4.1 to 6.1 mm (P = 0.01) (mean increase of 45%). The only complication was transient pulmonary edema in one patient. The PABBD procedure is a feasible and safe method for increasing pulmonary blood flow in a staged manner and may eliminate the need for surgical band removal in some cases.

Pulmonary Artery Banding

Proponents of a telemetrically adjustable pulmonary artery band (PAB) device have cited simplified postoperative management and shortened length of stay as advantages associated with that technology. This report concerns a recent experience with both conventional pulmonary artery banding (conv-PAB) and the telemetrically adjustable PAB FloWatch (FW-PAB). From January 2005 through December 2008, 19 consecutive infants underwent either conv-PAB (8 patients, mean age 3.5 months, mean weight 4.1 kg) or FW-PAB (11 patients, mean age 2.6 months, mean weight 3.1 kg). Indications for PAB were left ventricular retraining (1 patient in FW-PAB), palliation prior to biventricular repair (7 patients in conv-PAB and 10 in FW-PAB group), and staged univentricular repair (1 patient in conv-PAB). In-hospital mortality was 0%. In the FW-PAB group, 1 FloWatch device was removed because of hemodynamic compromise related to the bulk of the device. There were no major complications in the conv-PAB group and no differences between groups with respect to postoperative ventilation time or length of stay in the intensive care unit or in hospital. In the FW-PAB group, a mean of 3.1 ± 1.7 regulations per patient were undertaken. Of the regulations, 85% (29/34) were adjustments to tighten the device, and 15% (5/34) were to loosen it. During follow-up, 8 patients underwent intracardiac repair and pulmonary artery debanding: 4 in the conv-PAB group and 4 in the FW-PAB group. The course of patients in both groups after PAB were similar. Major differences in length of stay and resource utilization were not apparent.

Off-label use of an adjustable gastric banding system for pulmonary artery banding

BACKGROUND

Pulmonary artery banding is proposed as a first palliation in infants with complex congenital heart disease and high pulmonary blood flow. In addition, it may be used to retrain the left ventricle. Optimal tightening may be difficult to obtain, leading to reoperation. An implantable device for pulmonary artery banding with telemetric control was recently developed allowing for repeated adjustments, but it is presently limited to patients weighing less than 20 kg. In large animals, we tested an off-label adjustable gastric banding system for pulmonary artery banding.

METHODS AND RESULTS

Fourteen ewes weighing 50 to 75 kg underwent implantation of the Lap-Band device (BioEnterics Corp, Santa Barbara, Calif) around the main pulmonary artery through a left thoracotomy. All had functional evaluation with progressive occlusion and opening of the device at implantation and every 2 weeks until sacrifice immediately after implantation (group 1, n = 8), at 1 month (group 2, n = 3), at 3 months (group 3, n = 3), or death. Invasive pressure measurements in the right ventricle and aorta were carried out each time. Devices were easily implanted in all animals. Progressive occlusion and reopening were possible in all animals during each time point. Two animals died of right heart failure related to excessive tightening of the band. Retrieval of the device without any major damage was possible in 12 of 14 animals.

CONCLUSION

With this implantable device, we were able to adjust the pulmonary artery diameter in animals. Patients requiring left ventricle retraining and weighing more than 30 kg would benefit from the device's use in humans.

In the Footsteps of Senning: Lessons Learned From Atrial Repair of Transposition of the Great Arteries

The Senning operation has evolved from being the initial surgical correction that allowed survival in complete transposition of the great arteries to an integral part of the anatomic repair of congenitally corrected transposition. In patients with complete transposition, the Senning operation has given satisfactory initial and long-term surgical results, but the potential for right ventricular failure and atrial arrhythmias have drastically reduced its indications in the current era. The long-term follow-up and pertinent postoperative issues of the Senning operation will be reviewed, along with its newfound role in the anatomic repair of congenitally corrected transposition.

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.

Doppler-guided regulation of a telemetrically operated adjustable pulmonary banding system

OBJECTIVES

We report on the Doppler-assessed regulation of an adjustable pulmonary artery band (PAB) in an animal model and in our first group of patients.

BACKGROUND

Indications for pulmonary artery banding have expanded to include patients requiring a late arterial switch. A telemetry-operated, fully implantable, adjustable PAB system (FloWatch- PAB, Endoart SA, Lausanne, Switzerland) has been developed to facilitate these operations.

METHODS

The device was implanted in 13 minipigs (age one to five months, weights 3.2 to 12.0 kg). The main study was performed on nine minipigs with adjustments of the PAB at implantation and at 1, 3, 5, 8, and 12 weeks after, assessed by Doppler pressure gradients. Explanation was performed 12 weeks after surgery. A long-term histology study (6 months and 14 months after surgery) was done on the other four minipigs. After approval by the ethics committee, the device was implanted in eight patients with weights between 2.8 and 9 kg to decrease pulmonary blood flow and pressure and to retrain the left ventricle before arterial switch. The device was progressively tightened, with increasing transband Doppler gradients. Follow-up was one to three months.

RESULTS

An excellent correlation between transbanding systolic pressure gradient and degree of PAB constriction was encountered in the minipig study as well as in the human setting. No early or late deaths or reoperations occurred. Malfunction of the device was noted in three of 21 implanted devices. Two were related to surgically inflicted damage at implantation and one to an electronic problem that was fixed by resetting the control device.

CONCLUSIONS

The device offers a Doppler-controllable adjustment of pulmonary blood flow. It permits controlled tightening and release of the band, which improves perioperative and postoperative courses and decreases surgical interventions to adjust tightness of the band. It allows a protracted occlusion protocol, which may provide the best effect on retraining the left ventricle.