Pulmonary Artery Banding #1: Concept and Physiologic Rationale

Pulmonary artery banding (PAB) is a palliative flow-and-pressure restriction strategy used to control excessive pulmonary blood flow and limit pressure transmission to the distal pulmonary vascular bed. Rather than correcting the underlying cardiac anatomy, PAB deliberately introduces resistance into the pulmonary arterial pathway to create a more favorable hemodynamic state until definitive repair or the next stage of palliation can be performed.

Two configurations should be distinguished conceptually. Main pulmonary artery banding primarily restricts excessive pulmonary blood flow through a single proximal band and remains applicable in selected biventricular and single-ventricle lesions. Bilateral pulmonary artery banding (BPAB) places separate restrictions on the right and left pulmonary arteries and is physiologically distinct, particularly when the systemic circulation is ductal dependent. In that setting, BPAB is often part of a hybrid or resuscitative strategy rather than simply an alternative way to perform conventional PAB.

1. The Fundamental Purpose of PAB

The classic purpose of PAB is to reduce excessive pulmonary blood flow while protecting the pulmonary vascular bed from sustained exposure to excessive flow and pressure. Historically proposed physiologic goals include a distal pulmonary artery pressure of approximately 30–50% of systemic pressure in a biventricular circulation and, in a univentricular circulation, a distal pulmonary pressure as close as practical to the low pressures ultimately required for Fontan physiology, approximately a mean of 15 mm Hg [1].

These values should be understood as conceptual targets rather than universal operative endpoints. The appropriate degree of restriction depends on the underlying anatomy, pulmonary and systemic vascular resistance, ventricular function, atrioventricular valve competence, systemic outflow, and the intended next stage of treatment.

The fundamental goals are therefore:

• Restriction of excessive pulmonary blood flow
• Reduction of distal pulmonary arterial pressure
• Protection of the pulmonary vascular bed
• Reduction of pulmonary venous return and ventricular volume overload
• Improvement in the balance between pulmonary and systemic blood flow
• Creation of a stable interval before definitive or staged reconstruction

PAB is therefore best understood as a hemodynamic regulator, not merely as an anatomical narrowing of the pulmonary artery.

2. Pulmonary Overcirculation and Ventricular Volume Overload

After birth, pulmonary vascular resistance normally falls progressively. In congenital lesions with unrestricted communication between the systemic and pulmonary circulations, this reduction in pulmonary resistance may result in progressively increasing pulmonary blood flow.

The physiologic sequence is:

Increased Qp → increased pulmonary venous return → increased ventricular preload → chamber dilation → heart failure physiology

The clinical consequences may include tachypnea, increased work of breathing, feeding intolerance, poor weight gain, ventricular dilation, atrioventricular valve regurgitation, and progressive congestive heart failure.

In a biventricular circulation, excessive left-to-right shunting generally causes increased pulmonary venous return and volume loading of the left atrium and left ventricle. In a functionally univentricular circulation, the same ventricle must provide both pulmonary and systemic output:

COₛᵥ = Qp + Qs

When Qp is excessive, a substantial proportion of ventricular output is repeatedly recirculated through the pulmonary circulation. The ventricle therefore handles a large volume load without a corresponding improvement in effective systemic perfusion.

PAB interrupts this cycle by increasing resistance to pulmonary flow. Reduction in Qp decreases pulmonary venous return and therefore decreases ventricular preload and volume work.

3. PAB as an Artificial Resistance

A pulmonary artery band creates a localized mechanical obstruction proximal to the distal pulmonary vascular bed. It does not directly increase intrinsic pulmonary vascular resistance. Instead, it creates an additional resistance between the ventricle and pulmonary circulation.

This produces three closely related effects:

1. A pressure gradient develops across the band.
2. Pressure distal to the band decreases.
3. Pulmonary blood flow is restricted.

The reduction in distal pulmonary pressure and flow is especially important in infants in whom definitive repair must be deferred. Prolonged exposure of the pulmonary circulation to excessive flow and pressure may promote pulmonary vascular remodeling and eventually irreversible elevation of pulmonary vascular resistance.

Thus, one of the major long-term purposes of PAB is preservation of pulmonary vascular operability for later biventricular repair or maintenance of the low pulmonary vascular resistance required for staged single-ventricle palliation [1].

4. Main Pulmonary Artery Banding

Conventional main PAB places a single restriction around the main pulmonary artery proximal to the bifurcation. Blood destined for both lungs therefore passes through the same restricted segment.

Main PAB is most directly applicable when the principal physiologic problem is unrestricted pulmonary blood flow. By reducing Qp, it lowers distal pulmonary artery pressure, decreases pulmonary venous return, and relieves ventricular volume overload.

The degree of band restriction must be carefully calibrated. An excessively loose band fails to control pulmonary overcirculation, whereas an excessively tight band may produce severe hypoxemia, excessive proximal ventricular pressure loading, or inadequate pulmonary blood flow.

No single band gradient or arterial oxygen saturation has been established as universally optimal. A recent systematic review including 524 patients reported weighted means of approximately 64.2 mm Hg for peak PAB gradient, 89.3% for postoperative arterial oxygen saturation, and 3.5% for operative mortality [2]. However, only two studies met inclusion criteria, and these values represent observational aggregate findings rather than validated targets that should be applied to every patient.

Accordingly, band adequacy should not be determined from Doppler gradient alone. The gradient is inherently flow dependent and must be interpreted in the context of the entire circulation.

5. Main PAB in Single-Ventricle Physiology

PAB remains an important option in selected patients with single-ventricle anatomy and unrestricted pulmonary blood flow, particularly when there is no critical systemic outflow obstruction.

In a series of 54 patients undergoing isolated PAB for single-ventricle physiology, overall mortality after banding was 4%, and 7% required reoperation for band adjustment. Age at PAB did not significantly influence subsequent pulmonary vascular resistance or outcomes after bidirectional cavopulmonary connection, supporting the feasibility of performing PAB early in appropriately selected neonates rather than waiting for further postnatal reduction in PVR [3].

Another series of 73 patients with single-ventricle anatomy and unrestricted pulmonary blood flow reported 4% hospital mortality and approximately 86% five-year survival. However, 22% required reoperation before Glenn palliation, emphasizing that PAB is an interim strategy requiring active surveillance rather than a static intervention [4].

These data support main PAB as a reasonable first-stage option in selected single-ventricle patients, but they do not establish a universally optimal degree of band tightness.

6. Balancing Qp and Qs

In parallel circulations, pulmonary and systemic blood flow compete for available ventricular output. When pulmonary resistance is disproportionately low, Qp increases and effective systemic blood flow may become relatively inadequate.

This leads to an important principle:

A higher systemic arterial oxygen saturation does not necessarily represent a better circulation.

Marked pulmonary overcirculation may produce relatively high oxygen saturation while systemic perfusion remains compromised by excessive recirculation through the lungs.

By increasing pulmonary resistance, PAB can redistribute ventricular output:

↓ Qp → ↓ pulmonary venous return → ↓ ventricular volume load → relatively greater effective Qs

The goal is therefore not maximal saturation or minimal pulmonary flow. The goal is an appropriate balance between Qp and Qs that provides adequate pulmonary oxygen uptake while preserving systemic perfusion and reducing ventricular workload.

7. Bilateral Pulmonary Artery Banding Is Physiologically Different

BPAB should not be regarded simply as main PAB performed twice.

Separate bands are placed around the right and left pulmonary arteries while flow through the proximal main pulmonary artery remains available. This arrangement becomes particularly important in ductal-dependent systemic circulation.

In such a circulation, blood leaving the main pulmonary artery may follow three pathways:

Main PA → RPA

Main PA → LPA

Main PA → PDA → systemic circulation

Thus, BPAB regulates the amount of flow entering each lung while maintaining the pulmonary-artery-to-ductal pathway required for systemic perfusion [5].

This physiology is substantially different from conventional main PAB. Pulmonary flow depends not only on band tightness but also on the resistance of the ductal/systemic pathway and the relative pulmonary and systemic vascular resistances.

A particularly important implication is that systemic pathway obstruction may increase pulmonary blood flow despite apparently adequate bilateral bands. Excessive pulmonary flow in this setting should therefore not automatically be interpreted as evidence that the bands are too loose; obstruction to systemic output may be redirecting flow toward the lungs [5].

8. BPAB as a Hybrid or Resuscitative Strategy

BPAB has been used as part of staged or hybrid management for neonates with ductal-dependent systemic circulation and as a resuscitative option for high-risk single-ventricle patients considered poor candidates for conventional first-stage reconstruction.

In a single-center series of 24 high-risk single-ventricle neonates and infants treated with BPAB together with ductal stenting or maintenance of prostaglandin-mediated ductal patency, 15 patients (62.5%) subsequently reached Norwood palliation, transplantation, or second-stage palliation [6].

This experience illustrates the principal role of BPAB in this setting: stabilization and time-buying. The objective is to restrict pulmonary overcirculation while maintaining systemic output through the ductus, allowing recovery, growth, further anatomical assessment, or progression to a later definitive strategy.

Contemporary registry data further demonstrate that main and bilateral PAB populations should not be interpreted as equivalent. Among 3,367 PAB procedures recorded in a large congenital surgical database, 2,677 were main PAB and 690 were bilateral PAB. Operative mortality was 8% after main PAB and 26% after bilateral PAB [7]. This difference should not be interpreted as evidence that BPAB itself is intrinsically more hazardous, because bilateral banding is frequently used in considerably higher-risk patients with complex ductal-dependent systemic circulations or as part of rescue strategies. The data primarily demonstrate the markedly different case mix and risk profile associated with BPAB.

9. PAB as a Time-Buying Strategy

The value of PAB often lies in what it allows the surgeon and multidisciplinary team not to do immediately.

An effective band may permit:

• Somatic growth
• Recovery from prematurity or extracardiac illness
• Improvement in nutritional status
• Further assessment of ventricular adequacy
• Delayed complex intracardiac repair
• Progression toward Glenn/Fontan palliation
• Stabilization before later neonatal or infant reconstruction

In selected borderline anatomies, PAB may preserve time for determination of whether a biventricular or single-ventricle pathway is most appropriate.

Adjustable or dilatable strategies have further extended this concept. In a 16-patient series using a surgically placed dilatable PAB, five patients subsequently underwent transcatheter balloon dilation without procedural complication, permitting incremental increases in pulmonary blood flow as physiology and somatic size evolved [8]. Such techniques emphasize that the optimal pulmonary restriction at one stage may not remain optimal throughout growth.

10. Ventricular Training

PAB can also be used for a physiologically different purpose: ventricular training.

When a ventricle—most commonly the morphologic left ventricle—has been chronically exposed to low pressure, controlled pulmonary artery restriction can increase ventricular afterload and stimulate myocardial hypertrophy and increased ventricular mass.

In this setting, the primary objective is not reduction of pulmonary overcirculation but preparation of the ventricle for a future systemic workload. This application should therefore be distinguished mechanistically from conventional flow-restricting PAB, even though the same surgical principle of creating controlled pulmonary outflow obstruction is employed.

11. Complications and Failure Modes

PAB creates an intentional obstruction, and both inadequate and excessive restriction can be clinically important.

An under-restrictive band may result in:

• Persistent pulmonary overcirculation
• Persistent ventricular volume overload
• Continued heart failure
• Excessive distal pulmonary artery pressure
• Failure to protect the pulmonary vasculature

An excessively restrictive band may produce:

• Inadequate pulmonary blood flow
• Excessive cyanosis
• Excessive proximal ventricular pressure
• Hemodynamic instability

Recognized anatomical complications include band migration, distortion of the branch pulmonary arteries, erosion, pulmonary valve distortion, and subannular or infundibular hypertrophy [1]. These issues may complicate later repair and should be considered when selecting the band position and during longitudinal surveillance.

12. Assessing Whether the Band Is Appropriate

The success of PAB cannot be defined by one number. Assessment should integrate:

• Systemic arterial oxygen saturation
• Systemic arterial pressure and end-organ perfusion
• Distal pulmonary artery pressure
• Band gradient
• Ventricular systolic function
• Atrioventricular valve regurgitation
• Respiratory status
• Lactate and other markers of systemic oxygen delivery
• Clinical improvement in heart failure
• Somatic growth
• Anatomy of the pulmonary arteries and systemic outflow

The intended subsequent operation must also influence interpretation.

The central objective of PAB is therefore not to achieve a predetermined gradient or saturation but to construct an appropriate physiologic balance for the patient's anatomy and surgical pathway. Main PAB principally controls excessive pulmonary flow and protects the pulmonary vascular bed. Bilateral PAB, by contrast, can simultaneously restrict pulmonary flow while preserving ductal systemic output and therefore occupies a distinct role in hybrid and resuscitative strategies.

References

[1] Sharma R. Pulmonary artery banding: Rationale and possible indications in the current era. Ann Pediatr Cardiol. 2012;5(1):40-43. (PubMed Central (PMC))

[2] Awori MN, Awori JA, Hussein KM, Awori IN. 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. (Academic Journals)

[3] Ramakrishnan K, Alfares FA, Hammond-Jack K, Endicott K, Nettleton M, Zurakowski D, Jonas RA, Nath DS. Optimal Timing of Pulmonary Banding for Newborns with Single Ventricle Physiology and Unrestricted Pulmonary Blood Flow. Pediatr Cardiol. 2016;37(3):606-609. (PubMed)

[4] Alsoufi B, Manlhiot C, Ehrlich AC, Oster M, Kogon B, Mahle WT, Maher K, McCrindle BW, Kanter K. Results of palliation with an initial pulmonary artery band in patients with single ventricle associated with unrestricted pulmonary blood flow. J Thorac Cardiovasc Surg. 2015;149(1):213-220. (PubMed)

[5] Quarti A, Colaneri M, Baldinelli A, Oggianu A, Pozzi M. Bilateral Pulmonary Artery Banding. World J Pediatr Congenit Heart Surg. 2010;1(2):262-263. (Houston Methodist Scholars)

[6] Guleserian KJ, Barker GM, Sharma MS, Macaluso J, Huang R, Nugent AW, Forbess JM. Bilateral pulmonary artery banding for resuscitation in high-risk, single-ventricle neonates and infants: a single-center experience. J Thorac Cardiovasc Surg. 2013;145(1):206-214. (PubMed)

[7] Devlin PJ, Argo MB, Habib RH, McCrindle BW, Jegatheeswaran A, Jacobs ML, Jacobs JP, Backer CL, Overman DM, 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. (PubMed)

[8] Ligon RA, Latson LA, Ruzmetov MM, Chan KC, Turner II, Scholl FG, Bibevski S. Dilatable Pulmonary Artery Banding Palliation in Congenital Heart Disease. World J Pediatr Congenit Heart Surg. 2021;12(2):213-219. (journals.sagepub.com)