Muller and Dammann described pulmonary artery banding(PAB) for palliation of congenital heart disease(CHD) with pulmonary hypertension (PAH) secondary to increased pulmonary blood flow in 1952, a time when intra cardiac repair was virtually nonexistent. When it did come about, PAB continued to occupy an important place in surgical treatment of CHD, due to increased risk of cardiopulmonary bypass (CPB) in the very young infant. The purpose of PAB was to protect lungs from unrestricted pulmonary flow while allowing corrective surgery to be postponed to a safer future, when the cardiac structures of the child was bigger. Pulmonary artery banding itself has not been an entirely benign procedure, being associated with a not insignificant morbidity and mortality. Branch pulmonary artery distortion secondary to band migration, band erosion into pulmonary artery lumen, pulmonary valve distortion, subannular ventricular hypertrophy are all described complications. Trusler, et al., proposed guidelines for pulmonary artery banding for cyanotic and acyanotic situations. The target distal pulmonary artery pressure (PAP) is conventionally 30-50% of systemic for a biventricular heart, while it should be as close to the Fontan pressure (mean of 15 mm Hg), as possible, in a univentricular situation.
With time, CPB-associated risks have been reduced to a minimum, while mortality of PAB has still remained higher (these groups are no longer comparable as the straightforward septal defect would undergo one stage primary correction, while possibly only the higher risk group would be submitted for a PAB). In addition, separate risks of two procedures with an interim waiting period with possibility of intercurrent attrition increase the cumulative risk to above that for primary closure of a routine septal defect. Pulmonary artery banding is therefore today referred to more as a historical procedure in the surgical treatment of the straightforward septal defect.
PAB exists in its original role today for the small infants with
- Swiss cheese type of multiple ventricular septal defects
- Postponing the choice between biventricular and univentricular repair in atrioventricular or ventricular septal defects (VSD) with ventricular imbalance.
- Defects with complex anatomy, often associated with a common atrioventricular connection or a criss-cross heart, where a biventricular repair of better quality may be possible later in life when the cardiac structures are bigger.
- Univentricular physiology with unrestricted pulmonary blood flow to drop PAP and pulmonary vascular resistance to levels suitable for future univentricular palliation.
- The extremely marasmic, septic infant, or in one who presents with a contraindication for CPB, eg., recent intracranial bleed.
Newer indications that have joined the above list, aim at the following:
- Left ventricular preparation for an involuted subpulmonary left ventricle of late-presenting simple D-transposition of the great arteries (TGA), in preparation for an arterial switch operation.
- Left ventricular preparation and/or reduction of tricuspid regurgitation (TR) in congenitally corrected transposition of the great arteries (CCTGA) with tricuspid incompetence without sizeable VSD.
- PAB as an adjunct to another procedure, eg., 1. bidirectional Glenn shunt to maintain antegrade flow with acceptable superior caval pressures, 2. as part of a palliative arterial switch operation.
Controversial indications would include
- Routine initial PAB for CCTGA VSD in a proposed strategy towards preserving left ventricular function following anatomic repair.
- Adjunctive PAB along with physiological correction of late presenting simple TGA for future conversion to anatomic repair.
- PAB for reversing the advanced pulmonary vasculopathy of unoperated CHD with Eisenmenger's syndrome.
In this paper, Dehaki et al. present their five-years cumulative experience with PAB till April, 2010. All PABs were performed for PAH secondary to increased pulmonary blood flow situations.
Out of a total of 305 PABs in their series, 57.4% were for VSDs (large or multiple), 20.6% for atrioventricular septal defects, 3.9% for VSD with coarctation, 4.3% for double outlet of the right ventricle, 10.2% for TGAVSD, and 2.6% for single ventricle situations. In their own words, 20% had complex heart disease and sepsis while 45% had a weight below 4 kg. The mean age and weight at the time of PAB were 7.12 ± 5.2 months and 5.5 ± 1.6 kg, respectively.
PAB was classified as anatomically effective if it reduced the MPA diameter to 50% in the banded segment (achieved in 97%) and functionally effective if there was reduction of PAP to 50% of systemic pressure or below (achieved in 92%). This was achieved in equal measure by any of the three described methods of PAB that they mention, i.e., guided by direct pressure measurement, by Trusler's formula, or by relying only on O2 saturations without any pressure measurement, without any difference in efficacy.
In hospital PAB mortality was only 2%. The complication rate was also very small.
Completion of repair of 78% of the banded patients was carried out at a mean gap of 23 ± 10 months. The rest were on follow up. There was no attrition in the waiting period for the entire group (a total mean follow up of 39 ± 20 months). In-hospital mortality for the corrective procedure was 3%. Among the patients who underwent correction, most of them had removal of their bands and only 20% received a pulmonary artery augmentation by a patch. There was no difference in gradient in the MPA in the patched or nonpatched patients, postoperatively.
The authors conclude that PAB is still a low risk temporising option especially in centers ill-equipped for open cardiac surgery in the small child and a useful procedure for the group where CPB may be a high risk strategy even for centers routinely performing primary repairs.
The following discussion deals only with PAB for the indication which the above paper has dealt with.
The most notable feature of this publication is the very low complication rate following initial PAB, right through the interval period and including the second stage complete repair. For this, the authors needs to be congratulated for, achieving such low rates of negative outcomes, in a milieu which is less than ideal (as they themselves state), is no mean task.
I have selected some aspects of the paper and I mention my own thoughts on these: