Pulmonary Artery Banding #6: Bilateral Pulmonary Artery Banding

1. Concept and Physiologic Purpose

Bilateral pulmonary artery banding (bPAB) is a strategy in which the right and left branch pulmonary arteries are individually restricted to control pulmonary blood flow while preserving a separate pathway for systemic perfusion. It is most closely associated with hybrid palliation for hypoplastic left heart syndrome (HLHS) and related ductal-dependent systemic circulations, but it can also serve as a bridge-to-repair or bridge-to-decision strategy in selected high-risk neonates with complex congenital heart disease. Hybrid palliation can reduce the physiologic burden of immediate neonatal reconstruction by avoiding or deferring cardiopulmonary bypass, cardioplegic arrest, and extensive arch reconstruction [1].

The fundamental goals are:

• Restrict excessive pulmonary blood flow (Qp).
• Preserve systemic blood flow (Qs) through a patent ductus arteriosus (PDA).
• Reduce ventricular volume loading from pulmonary overcirculation.
• Maintain adequate systemic oxygen delivery.
• Stabilize high-risk neonates before definitive repair or subsequent staged palliation.

Therefore, bPAB should not be viewed simply as “two pulmonary artery bands.” It is a flow-partitioning strategy designed to redistribute ventricular output between the pulmonary and systemic circulations.

2. Why Bilateral Rather Than Main Pulmonary Artery Banding?

Conventional main pulmonary artery banding restricts the single proximal pulmonary outflow pathway and is appropriate when the objective is simply to reduce excessive pulmonary blood flow. In ductal-dependent systemic circulation, however, the pulmonary root and main pulmonary artery may also provide the pathway to the systemic circulation.

In HLHS, for example, systemic output is generated predominantly by the right ventricle:

RV → pulmonary valve → main pulmonary artery → PDA → descending aorta and retrograde aortic arch

A conventional main PA band would therefore obstruct not only pulmonary flow but also systemic output.

Bilateral PAB instead creates two controlled restrictions distal to the main pulmonary artery, at the right and left branch pulmonary arteries. The main PA–ductal pathway remains available for systemic perfusion.

The circulation consequently has two major outlets:

1. Restricted flow into the right and left pulmonary vascular beds
2. Preserved flow through the PDA into the systemic circulation

This distinction is the central physiologic rationale for bilateral rather than main PA banding.

3. The Hybrid Circulation

The classic hybrid stage I circulation for HLHS consists of three coordinated components:

1. Bilateral pulmonary artery banding
2. Maintenance of ductal patency
3. Adequate atrial-level communication

Each component addresses a different hemodynamic requirement.

The PA bands control Qp and limit pulmonary overcirculation. The PDA provides systemic perfusion. A sufficiently nonrestrictive atrial communication allows pulmonary venous blood to leave the left atrium and enter the systemic venous–ventricular pathway.

These components are interdependent. A technically satisfactory bPAB cannot compensate for a restrictive atrial septum or inadequate ductal systemic flow. Similarly, an unobstructed PDA does not prevent systemic hypoperfusion if excessive Qp continues through inadequately restrictive PA bands.

Hybrid palliation should therefore be understood as creation of a deliberately balanced parallel circulation, rather than as a collection of separate procedures [1].

4. Patient Selection: A Bridge for High-Risk Neonates

The evidence most strongly supports bPAB as a selective bridge strategy rather than a universally superior alternative to conventional neonatal reconstruction.

Potential candidates include neonates with:

• hemodynamic shock,
• active infection or sepsis,
• multiorgan dysfunction,
• severe preoperative instability,
• very low body weight or prematurity,
• uncertain prognosis,
• or borderline anatomy in which the ultimate single- versus biventricular pathway remains uncertain.

In a rescue series of 10 high-risk neonates with ductal-dependent systemic outflow obstruction, organ function improved in 9 patients following stabilization that included bPAB before conventional cardiopulmonary-bypass surgery [2]. A larger retrospective experience of 66 patients similarly identified shock and uncertainty regarding single- versus biventricular physiology as particularly useful indications; hospital mortality in that heterogeneous cohort was 11% [3].

More contemporary experience has also used bPAB with either continued prostaglandin therapy or ductal stenting to bridge high-risk neonates to delayed Norwood-type reconstruction or comprehensive stage II palliation [4].

Thus, the major advantage is often time: time for recovery from shock, infection, end-organ dysfunction, or low body weight, and time to clarify anatomy and long-term ventricular strategy.

5. Maintaining Ductal-Dependent Systemic Perfusion

Because systemic blood flow may depend on the ductus arteriosus, maintaining ductal patency is mandatory.

Continuous Prostaglandin E₁

Continuous prostaglandin E₁ (PGE₁) infusion can maintain ductal patency when bPAB is intended as relatively short-term stabilization. This avoids immediate ductal instrumentation but requires ongoing intravenous therapy and surveillance for adverse effects such as apnea and hypotension.

Ductal Stenting

For a more durable hybrid circulation, a PDA stent can establish a stable systemic outflow pathway. Ductal anatomy, length, tortuosity, and its relationship to the pulmonary artery and descending aorta influence technical feasibility.

Both approaches have been used clinically. In a contemporary high-risk series, 11 of 30 neonates were managed with continued prostaglandin therapy and 19 underwent ductal stenting after bPAB [4].

Regardless of technique, loss of ductal patency can rapidly compromise systemic perfusion and represents a potentially catastrophic failure of the hybrid circulation.

6. Atrial-Level Communication

In HLHS, pulmonary venous blood returns to the left atrium but cannot generate effective systemic output through the severely hypoplastic left-sided structures. Blood must therefore cross the atrial septum.

A restrictive atrial communication may result in:

• elevated left atrial pressure,
• pulmonary venous hypertension,
• pulmonary edema,
• impaired oxygenation,
• and progressive hemodynamic deterioration.

Atrial septostomy, atrial septal stenting, or surgical atrial septectomy may therefore be required.

Importantly, atrial-level restriction should be reassessed after the pulmonary circulation has been modified. Intraoperative flow-guided bPAB studies have emphasized that restriction at the foramen ovale may require specific subsequent atrial intervention [5].

The PA bands, PDA, and atrial septum must therefore be evaluated as a single physiologic system.

7. Physiology-Guided Band Adjustment

There is no universal band circumference, Doppler gradient, or oxygen saturation that reliably defines optimal bPAB in every neonate.

The physiologic objective is to establish an appropriate balance between Qp and Qs. Among the available quantitative data, a Qp/Qs near 1:1 is one of the clearest measurable targets.

In a 44-neonate retrospective study of hybrid bPAB with PDA stenting, a technique combining adjustable cuff-style banding with intraoperative assessment of branch pulmonary artery flow achieved Qp/Qs = 1:1 in 95.5% of patients, compared with 35.7% and 50% using two alternative fixed-band approaches [5]. This emphasizes that banding should be physiology guided rather than dimension guided alone.

Useful intraoperative variables include:

• systemic arterial pressure,
• arterial oxygen saturation,
• cerebral and somatic near-infrared spectroscopy,
• branch PA flow or Doppler measurements,
• ventricular function,
• lactate and acid-base status,
• and clinical evidence of systemic perfusion.

The bands should be tightened progressively while repeatedly reassessing the entire circulation.

8. Oxygen Saturation Is a Guide, Not the Goal

In a single-ventricle hybrid circulation, systemic arterial saturation in the range of approximately 75–85% is often compatible with appropriate pulmonary–systemic balance. However, saturation should never be interpreted in isolation.

A saturation of 90–95% may appear favorable but can indicate excessive pulmonary blood flow, with disproportionately low systemic flow. In this situation, the patient may remain tachypneic, poorly perfused, oliguric, or acidotic despite apparently excellent oxygen saturation.

Conversely, excessive band restriction may produce profound cyanosis and inadequate pulmonary blood flow.

The objective is therefore not maximal SpO₂ but adequate systemic oxygen delivery:

DO₂ = systemic blood flow × arterial oxygen content

Qp/Qs, blood pressure, hemoglobin concentration, NIRS, lactate, urine output, ventricular performance, and physical examination should all be interpreted together.

9. Pulmonary–Systemic Flow Competition

As neonatal pulmonary vascular resistance falls, unrestricted pulmonary blood flow can progressively dominate the circulation. In a parallel circulation, increasing Qp reduces the proportion of ventricular output available for systemic perfusion.

Clinical manifestations may include:

• relatively high oxygen saturation,
• tachypnea,
• systemic hypotension,
• poor peripheral perfusion,
• oliguria,
• increasing lactate,
• feeding intolerance,
• and progressive end-organ dysfunction.

Bilateral PAB increases resistance to pulmonary flow and redirects a greater proportion of ventricular output toward the PDA and systemic circulation.

This is the central physiologic effect of the procedure:

Restrict Qp → preserve Qs → improve systemic oxygen delivery

The target is balanced circulation, not simply creation of a high pressure gradient across each band.

10. Band Size, Duration, and Pulmonary Artery Consequences

The branch pulmonary arteries are particularly vulnerable to technique-related morbidity.

Band restriction that is too severe can produce localized distortion, intimal injury, or impaired branch PA growth. Conversely, bands that are too loose fail to control pulmonary overcirculation.

Duration also matters. Retrospective data indicate that smaller bands and banding lasting longer than approximately 90 days are associated with an increased likelihood of subsequent pulmonary artery intervention [6]. These findings argue against treating bPAB as an indefinitely stable form of palliation.

Both bands should provide reasonably symmetric restriction. Significant right–left imbalance may cause preferential pulmonary perfusion and asymmetric PA development.

The surgeon should also anticipate the next reconstruction when choosing band position. The technical objective is not merely effective neonatal restriction but preservation of branch pulmonary arteries that can subsequently be debanded and reconstructed.

11. Pulmonary Artery Reintervention: A Major Limitation

Pulmonary artery morbidity is one of the most consistent disadvantages of the hybrid approach.

In a retrospective comparison of 50 bPAB patients and 53 Norwood patients with ductal-dependent systemic circulation, overall PA growth and size were similar, but bPAB patients underwent significantly more subsequent PA interventions [6].

An HLHS-specific hybrid series demonstrated an even more striking difference: 18 of 21 hybrid survivors (86%) required branch PA intervention, compared with 9 of 29 Norwood patients (31%) [7]. Lower pre-Fontan pulmonary artery indices have also been reported after hybrid palliation.

These observations are important when counseling families and planning staged reconstruction. Avoiding neonatal bypass does not eliminate surgical burden; rather, part of that burden may be transferred to later pulmonary artery reconstruction or catheter-based reintervention.

12. Survival Compared With Norwood Palliation

Existing studies do not demonstrate that hybrid bPAB provides superior survival to conventional Norwood palliation.

An early comparison of 18 hybrid patients with 25 concurrent Norwood patients reported 1-year survival of approximately 68% after hybrid palliation versus 71.4% after Norwood palliation [8]. A contemporary high-risk cohort reported overall survival of 70% at a median follow-up of 9 months, with 90% operative survival after hybrid stage I [4].

These studies are observational and strongly influenced by patient selection, institutional strategy, and technical experience. Hybrid cohorts frequently include patients deliberately selected because conventional neonatal surgery is considered unusually high risk.

Accordingly, the appropriate conclusion is that hybrid bPAB can provide acceptable bridging survival in selected patients, not that it is superior to Norwood reconstruction.

13. Bridge to Single- or Biventricular Reconstruction

Although commonly discussed in the context of HLHS and single-ventricle palliation, bPAB can also preserve future decision-making in patients with borderline left-sided structures or other uncertain ventricular pathways.

Selected high-risk patients have undergone initial branch PA banding and ductal stenting followed several months later by either staged Norwood-type reconstruction or biventricular repair [9].

This makes bPAB particularly attractive when the immediate physiologic problem—pulmonary overcirculation with ductal-dependent systemic flow—must be addressed before the definitive anatomical strategy is certain.

For selected interrupted aortic arch or severe systemic outflow obstruction, the same principle may be applied as a bridge to later biventricular repair: pulmonary blood flow is restricted while ductal patency maintains systemic perfusion until the infant is better prepared for complete reconstruction.

14. Postoperative Surveillance

Management after bPAB should focus continuously on the balance between Qp and Qs.

Important variables include:

• systemic blood pressure and pulse quality,
• arterial oxygen saturation,
• cerebral and renal NIRS,
• urine output,
• lactate and acid-base trends,
• ventricular function,
• atrioventricular valve regurgitation,
• atrial-level restriction,
• ductal patency or stent function,
• and flow across each branch PA band.

Echocardiography should assess the right and left pulmonary arteries separately. A substantial difference in band velocities may indicate asymmetric restriction.

A patient with acceptable SpO₂ but rising lactate, decreasing NIRS, or worsening urine output should not be considered adequately balanced simply because the oxygen saturation appears satisfactory.

15. Clinical Perspective

Bilateral pulmonary artery banding is best regarded as a hybrid, bridge, or rescue strategy, rather than a definitive operation.

Its greatest potential value lies in carefully selected neonates in whom immediate conventional reconstruction carries disproportionate risk or in whom the definitive ventricular pathway remains uncertain. The procedure can reduce pulmonary overcirculation, preserve ductal-dependent systemic perfusion, permit recovery of organ function, and provide time before a more complex reconstruction [2–4].

However, this advantage comes with important trade-offs. Pulmonary artery distortion and subsequent intervention are more common than after Norwood palliation [6,7], and current evidence does not establish superior survival or neurodevelopmental outcome.

The key technical and physiologic principle is therefore:

Bilateral PAB should be individualized to achieve balanced pulmonary and systemic flow—not performed according to a single predetermined band diameter, gradient, or oxygen saturation.

Successful hybrid palliation depends on coordinated management of all three components: regulated pulmonary blood flow, reliable ductal systemic perfusion, and unrestricted atrial-level communication.

References

[1] Honjo O, Caldarone CA. Hybrid palliation for neonates with hypoplastic left heart syndrome: current strategies and outcomes. Korean Circ J. 2010;40(3):103-111.

[2] Russell RA, Ghanayem NS, Mitchell ME, Woods RK, Tweddell JS. Bilateral pulmonary artery banding as rescue intervention in high-risk neonates. Ann Thorac Surg. 2013;96(3):885-890.

[3] Sakurai T, Sakurai H, Yamana K, Nonaka T, Noda R, Otsuka R, Osawa T. Expectations and limitations after bilateral pulmonary artery banding. Eur J Cardiothorac Surg. 2016;50(4):626-631.

[4] Ceneri NM, Desai MH, Tongut A, Ozturk M, Ramakrishnan K, Staffa SJ, Zurakowski D, Donofrio MT, Downing T, d'Udekem Y, Jonas RA, Yerebakan C; Children's National Hospital Hybrid Working Group. Hybrid strategy in neonates with ductal-dependent systemic circulation and multiple risk factors. J Thorac Cardiovasc Surg. 2022;164(5):1291-1303.e6.

[5] Suvorov V, Zaitcev V, Andrzejczyk K. Effectiveness of bilateral pulmonary artery banding in patients with hypoplastic left heart syndrome and congenital heart defects with a functional single ventricle: a single-center retrospective study. Congenit Heart Dis. 2022;17(3):365-374.

[6] Davies RR, Radtke WA, Klenk D, Pizarro C. Bilateral pulmonary arterial banding results in an increased need for subsequent pulmonary artery interventions. J Thorac Cardiovasc Surg. 2014;147(2):706-712.

[7] Dave H, Rosser B, Knirsch W, Hübler M, Prêtre R, Kretschmar O. Hybrid approach for hypoplastic left heart syndrome and its variants: the fate of the pulmonary arteries. Eur J Cardiothorac Surg. 2014;46(1):14-19.

[8] Caldarone CA, Benson L, Holtby H, Li J, Redington AN, Van Arsdell GS. Initial experience with hybrid palliation for neonates with single-ventricle physiology. Ann Thorac Surg. 2007;84(4):1294-1300.

[9] Venugopal PS, Luna KP, Anderson DR, Austin CB, Rosenthal E, Krasemann T, Qureshi SA. Hybrid procedure as an alternative to surgical palliation of high-risk infants with hypoplastic left heart syndrome and its variants. J Thorac Cardiovasc Surg. 2010;139(5):1211-1215.