Pulmonary Artery Banding #2: PAB in Biventricular Repair

Pulmonary artery banding (PAB) is a palliative operation that creates a controlled obstruction in the main pulmonary artery to reduce excessive pulmonary blood flow and limit transmission of systemic or near-systemic pressure to the distal pulmonary vascular bed. In a biventricular circulation, its principal role is to control the consequences of a large left-to-right shunt when immediate definitive intracardiac repair is undesirable, technically unfavorable, or considered excessively high risk. Contemporary primary repair has markedly reduced the routine use of PAB, and the procedure is now generally reserved for selected infants with complex anatomy, severe illness, or other circumstances in which staged management offers a potential advantage [1].

1. Physiologic Rationale

1.1 Large left-to-right shunt physiology

In a patient with a large, nonrestrictive ventricular septal defect (VSD), pulmonary blood flow is determined primarily by the relative resistance of the systemic and pulmonary circulations rather than by restriction at the defect itself.

As pulmonary vascular resistance falls after birth, the pulmonary circulation becomes a low-resistance pathway. A substantial portion of ventricular output may therefore recirculate through the pulmonary vascular bed:

Large intracardiac shunt → excessive Qp/Qs → pulmonary overcirculation → increased pulmonary venous return → ventricular volume overload

In isolated VSD physiology, excessive pulmonary venous return produces left atrial and left ventricular volume loading. The left ventricle must eject not only effective systemic output but also the volume that repeatedly recirculates through the pulmonary circulation.

Clinically, this may produce tachypnea, increased work of breathing, feeding intolerance, diaphoresis, poor weight gain, recurrent respiratory illness, pulmonary edema, and progressive congestive heart failure.

1.2 Pulmonary vascular pressure exposure

A large nonrestrictive communication may also expose the pulmonary arteries to systemic or near-systemic pressure. The combination of high flow and high pressure increases pulmonary vascular stress and, if prolonged, may promote pathologic pulmonary vascular remodeling.

The physiologic objectives of PAB are therefore twofold:

1. Reduce excessive pulmonary blood flow and ventricular volume loading.
2. Reduce distal pulmonary arterial pressure and protect the pulmonary vascular bed.

PAB does not correct the intracardiac defect itself. Rather, it modifies the downstream resistance against which the shunt operates. It should therefore be understood as physiologic palliation rather than anatomic correction.

2. Hemodynamic Effect of Main PAB

A band placed around the main pulmonary artery creates a pressure gradient between the proximal pulmonary artery/right ventricle and the distal pulmonary circulation.

After appropriately restrictive banding:

↑ resistance to pulmonary flow → ↓ Qp → ↓ pulmonary venous return → ↓ ventricular volume load

At the same time:

PAB → ↓ distal pulmonary arterial pressure → reduced pulmonary vascular pressure exposure

For a patient with VSD physiology, the desired result is not complete elimination of pulmonary flow but restoration of a more favorable balance between Qp and Qs while maintaining adequate systemic oxygen delivery.

Conventionally, distal pulmonary arterial pressure in a biventricular circulation has been targeted to approximately 30–50% of systemic pressure [2]. This range should be regarded as a traditional physiologic guide rather than a universally validated endpoint.

3. Contemporary Indications

Modern congenital cardiac surgery permits early primary repair of most isolated VSDs and complete AVSDs. Consequently, conventional main PAB is no longer routine treatment for otherwise straightforward large-shunt lesions.

Its contemporary role is more selective. Current indications broadly include reduction of excessive pulmonary blood flow and, in other settings, ventricular training in preparation for later corrective surgery [3].

Within a biventricular repair pathway, situations in which PAB may still be considered include:

• Large VSD in an infant who is temporarily unsuitable for definitive repair
• Multiple or difficult-to-access muscular VSDs
• Selected AVSD patients in whom early complete repair is considered unfavorable
• VSD associated with coarctation or other complex anatomy requiring a staged strategy
• Complex congenital lesions with excessive pulmonary flow in a severely ill infant
• Very small or medically fragile patients in whom complex cardiopulmonary bypass and intracardiac reconstruction are judged excessively high risk
• Significant noncardiac illness that makes definitive repair undesirable at the initial operation

Historical experience similarly emphasized muscular or multiple VSDs, selected AVSDs, and VSD with coarctation among lesions in which PAB could provide useful palliation when primary repair was not appropriate [4].

Thus, the relevant question is no longer simply whether a large shunt is present. The more important question is:

Why should this patient undergo PAB rather than definitive repair now?

A clear staged-treatment rationale should exist before banding is selected.

4. Patient Selection and Potential Non-Responders

PAB is most effective when excessive pulmonary blood flow and pressure are major drivers of the patient's clinical deterioration. Persistent heart failure after apparently adequate restriction should prompt reassessment of the underlying physiology rather than reflexive tightening of the band.

Important competing or associated lesions include:

Pulmonary vascular disease

If pulmonary hypertension reflects substantially elevated or fixed pulmonary vascular resistance rather than predominantly unrestricted flow, mechanical reduction of Qp may not adequately stabilize the circulation. This is particularly relevant in patients presenting late.

Peripheral pulmonary stenosis

Preexisting branch or peripheral pulmonary artery obstruction may already create uneven resistance to pulmonary blood flow. Main PAB can then produce unpredictable pressure and flow distribution.

Significant pulmonary regurgitation

Pulmonary valve incompetence may alter the hemodynamic response to a distal obstruction and complicate right ventricular loading.

Left ventricular outflow tract obstruction

Restricting the pulmonary outlet changes ventricular loading conditions. Systemic outflow obstruction should therefore be carefully identified before PAB, particularly in complex ventricular–arterial relationships.

Severe atrioventricular valve regurgitation

In AVSD and related lesions, pulmonary overcirculation may coexist with substantial AV valve regurgitation. PAB reduces Qp but does not correct the regurgitant valve. If AV valve insufficiency is a dominant mechanism of heart failure, banding alone may provide inadequate palliation.

5. Operative Principle

In conventional biventricular palliation, the band is positioned around the main pulmonary artery between the pulmonary valve and the pulmonary arterial bifurcation.

The operation is technically more demanding than its apparent simplicity suggests. The band must provide sufficient restriction while avoiding:

• Pulmonary valve distortion
• Band migration
• Impingement on the right or left pulmonary artery
• Asymmetric branch pulmonary artery stenosis
• Excessive right ventricular pressure
• Inadequate pulmonary blood flow

Weight-based formulas have historically been used to estimate an initial band circumference. In a large clinical series, a formula-derived starting circumference was used with subsequent loosening when cyanosis or bradycardia indicated excessive restriction [5].

Such formulas should be considered starting points rather than definitive measurements. Final adjustment must reflect the individual patient's hemodynamic response.

6. How Tight Should the Band Be?

The central technical challenge of PAB is determining the appropriate degree of restriction.

Conventional pressure target

For biventricular circulation, distal pulmonary arterial pressure of approximately 30–50% of systemic pressure remains a widely cited conventional target [2].

However, contemporary evidence does not establish a single optimal distal pressure, Doppler gradient, or oxygen saturation applicable to every patient.

A 2025 systematic review identified only two eligible studies comprising 524 patients. The weighted mean peak PAB gradient was 64.2 mmHg, postoperative arterial oxygen saturation was 89.3%, and weighted operative mortality was 3.5%. Postoperative saturation represented approximately a 2% reduction from preoperative values above 90%, with measurements reported under an inspired oxygen concentration of approximately 50% [6].

These observations should not be interpreted as validated universal targets. The evidence base was small and heterogeneous, and the reported values describe pooled clinical experience rather than prospectively established thresholds.

Therefore, the goal should not be:

“Create a 64-mmHg gradient.”

Rather, the goal is:

Achieve sufficient reduction in Qp and distal PA pressure while preserving systemic oxygen delivery, ventricular function, and overall cardiac output.

7. Intraoperative Assessment

Appropriate band tightness should be assessed using multiple physiologic parameters whenever available:

• Systemic arterial pressure
• Systemic oxygen saturation
• Right ventricular or proximal pulmonary arterial pressure
• Distal pulmonary arterial pressure
• Ventricular systolic function
• AV valve regurgitation
• Systemic perfusion and cardiac output
• Visual assessment of the branch pulmonary arteries

A near-normal systemic saturation may be achievable in a typical acyanotic biventricular circulation, but no evidence-based universal saturation threshold has been established.

Similarly, a Doppler or directly measured pressure gradient must be interpreted in the context of flow. A high gradient with markedly reduced cardiac output is not evidence of a successful band.

8. Too Loose Versus Too Tight

PAB requires a balance between two physiologic failures.

Inadequately restrictive band

If the band is too loose:

• Qp remains excessive.
• Distal PA pressure remains elevated.
• Pulmonary vascular protection is incomplete.
• Ventricular volume overload persists.
• Heart failure may fail to improve.

Excessively restrictive band

If the band is too tight:

• Right ventricular pressure rises excessively.
• Pulmonary blood flow becomes inadequate.
• Systemic oxygen saturation falls.
• Right ventricular systolic function may deteriorate.
• Tricuspid regurgitation may increase.
• Systemic cardiac output may decrease.

The correct band is therefore not defined simply by circumference or gradient. It is defined by the resulting global hemodynamic balance.

9. Outcomes and Technical Limitations

Contemporary registry data confirm that PAB remains associated with clinically important risk. An analysis of 3,367 procedures in the Society of Thoracic Surgeons Congenital Heart Surgery Database included 2,677 main PAB procedures and reported an operative mortality of approximately 8% after main PAB [7]. This figure includes heterogeneous diagnoses and clinical conditions and should not be interpreted as lesion-specific mortality for elective biventricular palliation.

Individual institutional series also demonstrate the difficulty of achieving an optimal band. In one 61-patient experience, mortality was 8.2%, severe complications occurred in 49.15%, and 6.5% required band reoperation [8].

Band inadequacy may be particularly important. In a 135-patient series, 28.9% had an inadequate band at follow-up, increasing to 41.5% among patients banded before 3 months of age. Patients proceeding to later definitive repair had substantially higher mortality when the band remained inadequate at the time of repair [9].

These findings emphasize that PAB should not be viewed as a minor temporizing procedure. Its success depends on accurate initial adjustment and careful longitudinal surveillance.

10. Postoperative Surveillance

After successful banding, expected physiologic improvement includes:

• Decreased pulmonary overcirculation
• Reduced pulmonary venous return
• Reduced ventricular volume loading
• Improvement in congestive symptoms
• Better feeding and growth
• Reduced distal pulmonary arterial pressure

Serial echocardiography should assess:

• Band velocity and estimated gradient
• Right ventricular pressure
• Ventricular size and function
• AV valve regurgitation
• Branch pulmonary artery anatomy
• Pulmonary valve function
• Development of systemic outflow obstruction

Importantly, the band does not grow with the patient. As the child grows, the fixed band circumference may become progressively more restrictive.

Historical follow-up demonstrated reduction of pulmonary vascular resistance toward normal in appropriately banded young children and no progression of pulmonary vascular disease in the reported serially studied patients, although pulmonary valve thickening was observed in some cases [10].

11. Transition to Definitive Biventricular Repair

PAB should usually be incorporated into a clearly defined pathway toward later definitive repair.

Once the patient has achieved sufficient growth, medical stabilization, or resolution of the condition that initially precluded complete repair, definitive surgery should be reconsidered.

At subsequent repair:

1. The pulmonary artery band is removed.
2. The main and branch pulmonary arteries are inspected.
3. Band-related stenosis or distortion is reconstructed when necessary.
4. The intracardiac shunt is closed.
5. Associated AV valve or outflow lesions are addressed.

An inadequate band should not simply be tolerated until definitive repair. Historical data demonstrate that persistent band inadequacy may adversely affect later operative outcome [9].

12. Practical Concept

The fundamental biventricular PAB strategy can be summarized as:

Before PAB

Large left-to-right shunt

→ excessive Qp/Qs

→ pulmonary overcirculation

→ elevated pulmonary arterial pressure

→ increased pulmonary venous return

→ ventricular volume overload

After appropriately adjusted PAB

Controlled pulmonary arterial obstruction

→ reduced Qp

→ reduced distal pulmonary arterial pressure

→ reduced pulmonary venous return

→ reduced ventricular volume load

→ improved heart-failure physiology and pulmonary vascular protection

The essential concept is that the operative objective is not a particular band circumference or Doppler gradient. It is the creation of an appropriate physiologic balance between pulmonary and systemic flow while preserving ventricular performance and systemic oxygen delivery.

Key Points

• Main PAB is a physiologic palliative operation that restricts pulmonary blood flow without correcting the underlying intracardiac defect.
• In biventricular physiology, its primary purpose is to reduce excessive Qp/Qs, ventricular volume loading, and distal pulmonary arterial pressure.
• Contemporary primary repair has restricted its use mainly to severely ill, medically fragile, or anatomically complex patients who are not optimal candidates for immediate definitive repair.
• A distal PA pressure of approximately 30–50% of systemic pressure is a conventional biventricular target, but high-quality evidence defining an optimal pressure, gradient, or systemic saturation is lacking.
• Weight-based formulas can guide initial band circumference, but final adjustment must be based on the patient's actual hemodynamic response.
• Persistent instability despite apparently adequate restriction should prompt evaluation for pulmonary vascular disease, peripheral pulmonary stenosis, pulmonary regurgitation, LVOTO, severe AV valve regurgitation, or other competing physiology.
• Inadequate banding is clinically important and has been associated with worse outcomes at subsequent definitive repair.
• PAB should be regarded as a deliberate component of a staged strategy rather than a simple temporary procedure.

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References

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[3] Sasaki T. Pulmonary Artery Banding—Original, Current, and New Indications for Pulmonary Artery Banding. Nihon Ika Daigaku Igakkai Zasshi. 2023;19(2):148-155.

[4] Horowitz MD, Culpepper WS 3rd, Williams LC 3rd, Sundgaard-Riise K, Ochsner JL. Pulmonary artery banding: analysis of a 25-year experience. Ann Thorac Surg. 1989;48(3):444-450.

[5] Albus RA, Trusler GA, Izukawa T, Williams WG. Pulmonary artery banding. J Thorac Cardiovasc Surg. 1984;88(5 Pt 1):645-653.

[6] Mark NA, Jonathan AA, Khalif MH, Isaiah NA. Optimal main pulmonary artery banding for the protection of the pulmonary vascular tree: a systematic review. Afr Ann Thorac Cardiovasc Surg. 2025;17(2):12-17.

[7] Devlin P, Argo MB, Habib RH, McCrindle B, Jegatheeswaran A, Jacobs ML, Jacobs JP, Backer CL, Overman D, Karamlou T. Contemporary applications and outcomes of pulmonary artery banding: an analysis of The Society of Thoracic Surgeons Congenital Heart Surgery Database. Ann Thorac Surg. 2024;117(1):128-135.

[8] Valente AS, Mesquita F, Mejía JAC, Maia ICL, Souto Maior MCF, Branco KC, Pinto VC Jr, Carvalho W Jr. Pulmonary artery banding: a simple procedure? A critical analysis at a tertiary center. Rev Bras Cir Cardiovasc. 2009;24(3):327-333.

[9] Pinho P, von Oppell UV, Brink J, Hewitson J. Pulmonary artery banding: adequacy and long-term outcome. Eur J Cardiothorac Surg. 1997;11(1):105-111.

[10] Hunt CE, Formanek G, Levine MA, Castaneda A, Moller JH. Banding of the pulmonary artery: results in 111 children. Circulation. 1971;43(3):395-406.