Single Ventricle Palliation #3: Pulmonary Artery Banding

Stage I Alternative: Pulmonary Artery Banding

Pulmonary artery banding (PAB) is a physiologic palliative strategy used to control excessive pulmonary blood flow in selected patients with single-ventricle physiology. In this setting, the purpose of PAB is not to correct the underlying cardiac anatomy, but to rebalance the circulation by restricting pulmonary blood flow, protecting the pulmonary vascular bed, reducing systemic ventricular volume loading, and preserving effective systemic output.

In infants with functional single ventricle and unrestricted pulmonary blood flow, early protection of the pulmonary vascular bed is essential for maintaining candidacy for subsequent cavopulmonary palliation and eventual Fontan circulation [1]. Contemporary series have shown that initial PAB can provide acceptable short- and mid-term outcomes in selected single-ventricle patients, including those with concomitant arch obstruction, although results are strongly influenced by associated anatomy, extracardiac anomalies, and institutional strategy [2].

1. Hemodynamic Problem Before PAB

In single-ventricle physiology, the systemic ventricle supports both pulmonary and systemic circulations. Therefore, the total output of the single ventricle can be conceptualized as:

COsv = Qp + Qs

where Qp represents pulmonary blood flow and Qs represents systemic blood flow.

After birth, pulmonary vascular resistance normally falls. In patients with unrestricted pulmonary blood flow, this fall in pulmonary vascular resistance may cause excessive Qp. As pulmonary blood flow increases, the balance between Qp and Qs becomes unstable.

The major consequences are:

1. Pulmonary overcirculation

Excessive pulmonary blood flow increases pulmonary venous return and may lead to pulmonary congestion, tachypnea, feeding difficulty, and poor weight gain.

2. Systemic ventricular volume overload

Increased pulmonary venous return returns to the atrium and then to the single ventricle, increasing preload and ventricular work.

3. Vulnerable systemic output

Because the single ventricle must distribute output between the pulmonary and systemic circuits, excessive pulmonary runoff may reduce effective systemic perfusion.

Thus, the central problem is not only “too much blood flow to the lungs.” The deeper physiologic issue is that excessive Qp can compete with Qs, producing systemic hypoperfusion despite high total ventricular output.

2. Physiologic Goal of Pulmonary Artery Banding

PAB creates a controlled obstruction at the pulmonary artery level. By increasing resistance to pulmonary blood flow, it reduces Qp and shifts the circulation toward a more favorable Qp/Qs relationship.

The principal goals are:

• Restriction of excessive pulmonary blood flow
• Protection of the pulmonary vascular bed from pressure and flow overload
• Reduction of pulmonary venous return
• Relief of systemic ventricular volume loading
• Preservation of systemic output
• Stabilization before the next stage of palliation or definitive repair

This concept is particularly important in single-ventricle physiology because the ventricle is already responsible for both circulations. Reducing unnecessary pulmonary flow can improve systemic perfusion, decrease ventricular volume load, and preserve the pulmonary vascular bed for future cavopulmonary circulation.

3. Mechanism After PAB

After band placement, pulmonary blood flow is intentionally limited. This produces several important downstream effects.

3.1 Reduction in Qp

The band narrows the pulmonary artery lumen and increases resistance to forward flow into the pulmonary circulation. As Qp decreases, pulmonary congestion improves.

3.2 Reduction in pulmonary venous return

Because less blood passes through the lungs, less blood returns to the atrium and ventricle. This reduces systemic ventricular preload and decreases volume loading.

3.3 Preservation of Qs

By reducing excessive pulmonary runoff, a greater proportion of single-ventricle output can be directed toward the systemic circulation. This is the key physiologic benefit in patients with vulnerable systemic perfusion.

3.4 Protection of the pulmonary vascular bed

Chronic exposure to excessive pulmonary blood flow and pressure may promote pulmonary vascular remodeling. PAB therefore protects not only the immediate circulation but also the future Fontan pathway, where low pulmonary vascular resistance is essential.

4. PAB in the Single-Ventricle Pathway

PAB may be used in several single-ventricle scenarios, but its role depends on the underlying anatomy, systemic outflow status, pulmonary blood flow pattern, and overall surgical plan.

4.1 Conventional main pulmonary artery banding

In patients with single-ventricle physiology and unrestricted pulmonary blood flow without critical ductal-dependent systemic circulation, a main pulmonary artery band may be used to limit Qp. This approach is most relevant when pulmonary overcirculation and ventricular volume overload are the dominant physiologic problems.

A staged strategy using PAB in infants with functional single ventricle and unobstructed pulmonary blood flow has been reported to provide acceptable operative and mid-term mortality, without compromising later Damus–Kaye–Stansel reconstruction or completion Fontan palliation [1]. More recent experience has similarly shown that PAB can be an acceptable initial palliative procedure in selected single-ventricle patients with unrestricted pulmonary blood flow, with reported 5-year survival of 86% after initial PAB in one contemporary cohort [2].

4.2 Bilateral pulmonary artery banding

In hypoplastic left heart syndrome and related ductal-dependent systemic circulations, bilateral pulmonary artery banding is often used as part of a hybrid Stage I strategy. In this approach, the right and left pulmonary arteries are banded separately to control pulmonary blood flow, while systemic output is maintained through the ductus arteriosus, usually with prostaglandin infusion and/or ductal stenting.

The hybrid strategy was developed as an alternative to neonatal Norwood palliation, particularly for high-risk neonates or patients in whom avoidance of cardiopulmonary bypass, cardioplegic arrest, and deep hypothermic circulatory arrest during the initial neonatal period is desirable [3, 4]. The essential physiologic targets of hybrid Stage I palliation are:

• Controlled pulmonary blood flow through bilateral PA bands
• Maintenance of systemic blood flow through the ductus arteriosus
• Adequate atrial-level communication
• Preservation of systemic, coronary, and cerebral perfusion
• Stabilization until comprehensive Stage II reconstruction, transplantation, or an alternative pathway

4.3 Bridge strategy

PAB may function as a bridge to several possible pathways:

• Bidirectional Glenn procedure
• Fontan completion
• Norwood or comprehensive Stage II reconstruction
• Damus–Kaye–Stansel procedure when systemic outflow obstruction is present or develops
• Biventricular conversion in selected borderline anatomies
• Cardiac transplantation
• Further somatic growth and clinical stabilization

This flexibility is one of the major advantages of PAB. Rather than committing all patients immediately to a single pathway, PAB can stabilize the circulation while allowing time for anatomic clarification, physiologic reassessment, and institutional decision-making.

5. Clinical Outcomes and Program Evolution

Comparative studies have shown that hybrid and Norwood strategies can achieve broadly comparable survival in selected populations, although they differ substantially in operative burden, interstage management, and later reintervention profile.

A single-center comparison of hybrid and Norwood palliation demonstrated equivalent survival, comparable pulmonary artery growth and hemodynamics, and reduced hospital resource utilization in the hybrid group [5]. Similarly, a later comparison of patients undergoing Stage II palliation after hybrid or Norwood Stage I showed equivalent survival after Stage II and subsequent Fontan completion, although the hybrid group had a higher pulmonary artery reintervention rate and smaller pulmonary artery size at later evaluation [6].

These findings suggest that hybrid palliation should not be viewed as universally superior or inferior to Norwood palliation. Rather, it is a different strategy with a different distribution of risk. The hybrid approach may reduce the physiologic and operative burden during the neonatal period, but it may shift complexity to later stages, especially at comprehensive Stage II reconstruction.

6. High-Risk Neonates and Resuscitative Use

Bilateral PAB can also be used as a resuscitative strategy in critically ill, high-risk neonates and infants with single-ventricle physiology. This is particularly relevant in patients considered too unstable for conventional neonatal Stage I palliation.

In one single-center experience, bilateral PAB with ductal stenting or prostaglandin maintenance was used in high-risk single-ventricle neonates and infants, allowing survival to later Norwood palliation, comprehensive Stage II, or primary transplantation in a substantial proportion of patients [7]. This supports the concept that bilateral PAB can function as a temporary stabilizing platform rather than a definitive solution.

Bilateral PAB has also been applied to complex congenital heart disease beyond classic HLHS, particularly in patients with arch anomalies, shock, very small body size, or uncertain suitability for single-ventricle versus biventricular repair. In one series, outcomes improved after modification of banding strategy, and patients weighing less than 2.5 kg were more likely to gain weight after bilateral PAB [8].

7. Technical and Physiologic Considerations

The effectiveness of PAB depends on achieving the correct degree of restriction. Both under-banding and over-banding can be harmful.

7.1 Under-banding

If the band is too loose, pulmonary overcirculation persists. The patient may continue to demonstrate:

• Tachypnea
• Pulmonary edema
• Feeding difficulty
• Poor weight gain
• Ventricular volume overload
• Inadequate systemic perfusion

Persistent excessive Qp may also continue to expose the pulmonary vascular bed to high flow and pressure.

7.2 Over-banding

If the band is too tight, pulmonary blood flow becomes insufficient. This may produce:

• Severe cyanosis
• Inadequate oxygen delivery
• Acidosis
• Ventricular dysfunction
• Distortion or stenosis of the pulmonary arteries

The target is therefore not maximal restriction, but controlled balance. The band must provide enough pulmonary blood flow for oxygenation while preventing pulmonary overcirculation and systemic steal.

7.3 Bilateral PAB-specific concerns

Bilateral PAB requires meticulous attention to band position and tightness. The bands must restrict flow without causing excessive distortion of the branch pulmonary arteries. This is especially important because the branch pulmonary arteries will later become the passive vascular pathway for Glenn and Fontan circulation.

8. Limitations of Hybrid Palliation and PA Banding

Although PAB and hybrid Stage I palliation can stabilize the early circulation, several limitations must be recognized.

8.1 Pulmonary artery stenosis and reintervention

Pulmonary artery stenosis is one of the most important limitations after bilateral PAB and hybrid palliation. In comparative studies, hybrid patients have shown higher pulmonary artery reintervention rates and smaller pulmonary artery indices at later evaluation [6]. Left pulmonary artery compromise is particularly important. One study reported a 50% cumulative pulmonary artery intervention rate after Stage II, with most interventions targeting the left pulmonary artery [9].

8.2 Shift of surgical complexity to Stage II

Hybrid Stage I palliation may avoid neonatal cardiopulmonary bypass, but it often makes the next operation more complex. Comprehensive Stage II reconstruction may require arch reconstruction, ductal stent removal, pulmonary artery reconstruction, atrial septectomy, and superior cavopulmonary connection in a single operation.

8.3 Patient selection

PAB is not equally suitable for all single-ventricle patients. Outcomes are less favorable in patients with high-risk morphology, heterotaxy, unbalanced atrioventricular septal defect, mitral atresia, genetic syndromes, or significant extracardiac anomalies [2]. Therefore, the decision to use PAB must integrate anatomy, physiology, institutional experience, and the intended long-term pathway.

9. PAB and the Future Fontan Pathway

The long-term success of single-ventricle palliation depends heavily on the condition of the pulmonary vascular bed. A successful Fontan circulation requires:

• Low pulmonary vascular resistance
• Adequate pulmonary artery size
• Minimal pulmonary artery distortion
• Unobstructed systemic venous pathways
• Preserved ventricular function
• Controlled atrioventricular valve regurgitation
• Acceptable end-diastolic pressure

PAB should therefore be understood as a protective and strategic intervention. It protects the pulmonary vasculature from excessive flow and pressure, reduces the volume burden on the systemic ventricle, and preserves the possibility of later staged palliation. Long-term institutional experience with hybrid strategies, such as the Giessen Hybrid approach, supports the concept that bilateral PAB can be incorporated into a durable staged pathway for selected patients with HLHS and related variants [10].

10. Clinical Summary

Pulmonary artery banding is a strategic method of flow control in selected patients with single-ventricle physiology. Before banding, excessive pulmonary blood flow may dominate the circulation, producing pulmonary overcirculation, systemic ventricular volume overload, and vulnerable systemic output. After banding, Qp is reduced, pulmonary venous return decreases, systemic ventricular volume loading improves, and systemic output may be better preserved.

In classic single-ventricle physiology with unrestricted pulmonary blood flow, main PAB can protect the pulmonary vascular bed and support progression toward Glenn and Fontan palliation. In HLHS and related ductal-dependent systemic circulations, bilateral PAB is a central component of hybrid Stage I palliation, where it controls pulmonary blood flow while systemic perfusion is maintained through the ductus arteriosus.

The essential principle is controlled balance: enough pulmonary blood flow to maintain oxygenation, but not so much that systemic perfusion, ventricular function, or future pulmonary vascular suitability is compromised. PAB is therefore best understood not as a simple mechanical narrowing of the pulmonary artery, but as a physiologic tool for staging, stabilization, and preservation of future surgical options.

References

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[2] Alsoufi B, Manlhiot C, Ehrlich A, Oster M, Kogon B, Mahle W, Maher K, McCrindle B, 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.

[3] 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.

[4] Caldarone CA, Benson LN, 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.

[5] Honjo O, Benson LN, Mewhort HE, Predescu D, Holtby H, Van Arsdell GS, Caldarone CA. Clinical outcomes, program evolution, and pulmonary artery growth in single ventricle palliation using hybrid and Norwood palliative strategies. Ann Thorac Surg. 2009;87(6):1885-1892.

[6] Baba K, Kotani Y, Chetan D, Chaturvedi RR, Lee KJ, Benson LN, Grosse-Wortmann L, Van Arsdell GS, Caldarone CA, Honjo O. Hybrid versus Norwood strategies for single-ventricle palliation. Circulation. 2012;126(11 Suppl 1):S123-S131.

[7] 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.

[8] 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.

[9] Rahkonen O, Chaturvedi RR, Benson LN, Honjo O, Caldarone CA, Lee KJ. Pulmonary artery stenosis in hybrid single-ventricle palliation: high incidence of left pulmonary artery intervention. J Thorac Cardiovasc Surg. 2015;149(4):1102-1110.

[10] Schranz D, Bauer A, Reich B, Steinbrenner B, Recla S, Schmidt D, Apitz C, Thul J, Valeske K, Bauer J, Müller M, Jux C, Michel-Behnke I, Akintürk H. Fifteen-year single center experience with the “Giessen Hybrid” approach for hypoplastic left heart and variants: current strategies and outcomes. Pediatr Cardiol. 2015;36(2):365-373.