Feasibility of reversible pulmonary artery banding: early results and intermediate-term follow-up

Right Ventricular Pressure Overload and Pathophysiology of Growing Porcine Biomodel

The primary objective was to create a clinically relevant model of right ventricular hypertension and to study right ventricular myocardial pathophysiology in growing organism. The secondary objective was to analyse the effect of oral enoximone (phosphodiesterase inhibitor) therapy on right ventricular haemodynamic parameters and myocardial changes in biomodel of right ventricular hypertension. The study included a total of 12 piglets of 42 days of age. Under general anaesthesia, pulmonary artery banding (PAB) was performed surgically to constrict the main pulmonary artery to about 70-80 % of its original dimension. The study presented two groups of animals labelled C (control animals with PAB; n = 8) and E (animals with PAB and oral administration of enoximone; n = 4). Direct pressure and echocardiographic measurements were taken during operation (time-1), and again at 40 days after surgery (time-2). The animals were killed, and tissue samples from the heart chambers were collected for quantitative morphological assessment. Statistical analysis was performed on all acquired data. At time-2, the median weight of animals doubled and the median systolic pressure gradient across the PAB increased (46.59 ± 15.87 mmHg vs. 20.29 ± 5.76 mmHg; p < 0.001). Changes in haemodynamic parameters were compatible with right ventricular diastolic dysfunction in all the animals. Apoptosis, tissue proliferation and fibrosis were identified in all the myocardial tissue samples. Right ventricular pressure overload leads to increased apoptosis of cardiac myocytes, proliferation and myocardial fibrosis. Our study did not show evidence of haemodynamic benefit or myocardial protective effect of oral enoximone treatment.

Vascular histopathologic reaction to pulmonary artery banding in an in vivo growing porcine model

Pulmonary artery banding (PAB) is used as a surgical palliation to reduce excessive pulmonary blood flow caused by congenital heart defects. Due to the lack of microscopic studies dealing with the tissue remodeling caused by contemporary PAB materials, this study aimed to assess histologic changes associated with PAB surgery by analyzing local tissue reaction to the presence of Gore-Tex strips fixed around the pulmonary artery. Gore-Tex strips were used for PAB in a growing porcine model. After 5 weeks, histologic samples with PAB (n = 5) were compared with healthy pulmonary arterial segments distal to the PAB or from a sham-treated animal (n = 1). Stereology was used to quantify the density of the vasa vasorum and the area fraction of elastin, smooth muscle actin, macrophages, and nervi vasorum within the pulmonary arterial wall. The null hypothesis stated that samples did not differ histopathologically from adjacent vascular segments or sham-treated samples. The PAB samples had a greater area fraction of macrophages, a lower amount of nervi vasorum, and a tendency toward decreased smooth muscle content compared with samples that had no PAB strips. There was no destruction of elastic membranes, no medionecrosis, no pronounced inflammatory infiltration or foreign body reaction, and no vasa vasorum deficiency after the PAB. All the histopathologic changes were limited to the banded vascular segment and did not affect distal parts of the pulmonary artery. The study results show the tissue reaction of palliative PAB and suggest that Gore-Tex strips used contemporarily for PAB do not cause severe local histologic damage to the banded segment of the pulmonary arterial wall after 5 weeks in a porcine PAB model.

Endoluminal pulmonary artery banding: technique, applications and results

BACKGROUND

Occasionally pulmonary artery banding is necessary to reduce pulmonary arterial blood flow and pressure in patients who cannot be repaired in a single stage. Traditional extraluminal PAB can be associated with significant morbidity. We describe our technique, applications, and results of endoluminal pulmonary artery banding (EPAB) with and without creation of an aortopulmonary window (APW) for complex cardiac anomalies.

METHODS

Thirty-two patients underwent EPAB; 20 patients had simultaneous creation of an APW. Median patient age was 40 days (range, 2 to 3,210); median weight was 3.5 kg (range, 2.4 to 23 kg). Endoluminal pulmonary artery banding fenestrations of 2 to 8 mm were centrally placed in a Dacron patch that was attached circumferentially and intraluminally in the main pulmonary artery. Fenestrations were sized by presence of APW and patient weight. Thirty-one of 32 patients underwent associated cardiac procedures. The mean follow-up period was 2.6 years (range, 0 to 15.5).

RESULTS

Overall early mortality was 31% (10 of 32); 8% in EPAB alone (1 of 12) and 45% for EPAB+APW (9 of 20). Of the early deaths, 7 of 10 had severe, preoperative ventricular dysfunction. There was 1 early EPAB-related complication requiring band revision for relief of partial obstruction of the APW. At hospital dismissal, the mean pressure gradient after EPAB was 55.1 +/- 8.4 mm Hg as assessed by echocardiography. No patient experienced distal pulmonary hypertension, distortion, or band occlusion. There were 6 late deaths. At late follow-up, 5 patients underwent band revision, and complete repair was accomplished in 10 patients.

CONCLUSIONS

Endoluminal pulmonary artery banding provided a consistently effective and durable reduction in pulmonary arterial blood flow with no pulmonary artery distortion. Early mortality was low for EPAB alone. Endoluminal pulmonary artery banding alone is preferred when controlled pulmonary blood flow and cardiopulmonary bypass are required to address intracardiac abnormalities. The role of EPAB with APW needs to be defined.

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.

Absorbable pulmonary artery band

Absorbable pulmonary artery banding may be a useful method of avoiding further operation or angioplasty in patients whose underlying lesion has a natural history of resolution. We report 2 cases of absorbable pulmonary artery banding using braided Dexon. In both cases the bands functioned well initially and were completely resorbed after 2 years and 6 months, respectively.