Subaortic Stenosis in Single-Ventricle Physiology (#5) — Surgical Management Summary

Subaortic Stenosis in Single-Ventricle Physiology (#5) — Surgical Management Summary

Single ventricle AND (tricuspid atresia OR double-inlet left ventricle) AND transposition AND (bulboventricular foramen OR interventricular connection) AND (subaortic stenosis OR systemic ventricular outflow obstruction) AND pulmonary artery banding progression.

(palliative arterial switch OR Damus–Kaye–Stansel OR Norwood-type OR arch repair AND PAB OR subaortic resection) AND outcomes (reintervention, Glenn/Fontan completion, mortality, pulmonary artery growth).

Subaortic Stenosis in Single-Ventricle TGA Substrates

Why it matters in TA/TGA and DILV/TGA

In TA with TGA and DILV with TGA, systemic output frequently depends on an “outlet pathway” from the dominant ventricle to the systemic great artery—most commonly the bulboventricular foramen (BVF) / interventricular connection. Over time, this pathway may become restrictive, creating systemic ventricular outflow tract obstruction (SVOTO)—often labeled “subaortic stenosis (SAS).” In these patients, SAS is rarely a primary valve lesion; it is fundamentally a geometry + growth problem: systemic flow must traverse a pathway that may not grow in proportion to the child or may become functionally restrictive with changing loading conditions. [1] (PubMed)

A practical consequence is that SAS is dynamic: a pathway that appears “acceptable” early can become problematic later—particularly after pulmonary artery banding (PAB), when ventricular loading, hypertrophy, and streaming can change.

1) Core decision point

“Is SAS significant right now?”

This is the first fork in management because it determines whether your initial operation must create/bypass a reliable systemic outlet immediately—or whether you can safely prioritize arch stability + pulmonary protection while monitoring for later SAS evolution.

A. Significant SAS (+)

You already have an inadequate systemic outlet (e.g., restrictive BVF, small systemic outflow, unfavorable RVOT/aortic geometry). The initial palliation should not “wait and see”—it should establish a durable systemic outflow strategy from the start.

B. Significant SAS (−)

Systemic outflow is currently acceptable, but many of these patients still present with arch obstruction and/or pulmonary overcirculation. Here, the near-term goals are:

1. Restore arch continuity (eliminate ductal dependence / stabilize systemic perfusion)
2. Control Qp (lung protection) using band physiology

…with explicit surveillance for SAS progression.

2) Strategy A — Arch repair + PAB when SAS is not significant

Indication and rationale

When arch obstruction is present (coarctation/arch hypoplasia/interruption spectrum) but SAS is not yet significant, an initial approach of arch repair + PAB is a staged, risk-balanced strategy:

• Arch repair addresses the immediate systemic vulnerability.
• PAB reduces pulmonary overcirculation, protects the pulmonary vascular bed, and rebalances Qp:Qs—particularly valuable in “shunt physiology” where pulmonary runoff can steal systemic output.

The built-in limitation: SAS may emerge during follow-up

Multiple clinical observations across decades emphasize that PAB can be followed by progression of SAS/SVOTO in these substrates, requiring timely recognition and escalation. The key message is not “never band,” but rather: band with a plan, and do not tolerate a slowly tightening outlet pathway without action. [2,3] (PubMed)

What to do if SAS progresses

If follow-up suggests evolving SVOTO after arch repair + PAB, typical escalation options include (often aligned with Stage II timing when feasible):

• Direct relief: subaortic muscle resection ± BVF (VSD) enlargement (when anatomy and conduction risk are acceptable)
• Bypass strategy: Damus–Kaye–Stansel (DKS), frequently integrated with bidirectional Glenn (BDG) when timing is appropriate

This is the strength of the staged pathway: stabilize the arch and lungs early when SAS is mild, but maintain a clear “exit ramp” if SVOTO declares itself.

3) Strategy B — Palliative arterial switch operation (pASO) for significant SAS

Concept

A palliative arterial switch reassigns the aorta to the dominant LV, thereby eliminating a BVF/RV/RVOT-dependent systemic pathway and relieving the fundamental outflow constraint.

Why it can be attractive (in selected anatomy)

• It addresses the “root cause” of SVOTO by aligning the systemic great artery with the dominant ventricle.
• It preserves a physiologic route to BDG → Fontan in appropriately selected patients.
• Contemporary longitudinal experience supports that pASO can be part of a durable pathway to Fontan completion when anatomy is favorable and planning is deliberate. [5,6] (PubMed)

Long-term considerations to keep in mind

Because pASO uses the same fundamental arterial switch construct, follow-up should incorporate awareness of neo-aortic root dilation and neo-aortic regurgitation—recognized late issues after ASO populations—while interpreting their relevance in the palliative single-ventricle setting. [8] (PubMed)

4) Strategy C — Norwood-type pathway (DKS + systemic-to-pulmonary shunt) for significant SAS

Concept (“shunt physiology”)

When significant SAS is present and the native outlet cannot be trusted, a Norwood-type approach establishes systemic outflow via DKS (bypassing the subaortic region) and provides pulmonary blood flow using a systemic-to-pulmonary shunt (e.g., modified BTT shunt).

Why it remains a core solution

• DKS is a time-tested method to bypass SVOTO in univentricular hearts. [7] (PubMed)
• Comparative experiences in neonates with single-ventricle + systemic obstruction have shown meaningful differences in reintervention burden between early PAB-based strategies and Norwood-type approaches, reinforcing why many teams favor establishing a robust systemic outlet early when obstruction is present. [4] (PubMed)

5) A decision-oriented “textbook” way to choose

Rather than asking, “Which operation is best?”, the safer framing is:

1. What is the systemic outlet today?
• Is BVF/interventricular connection restrictive now?
• Is there evidence of systemic ventricular hypertension, low output, or Doppler acceleration/turbulence?
2. What is the arch requirement?
• If the arch is compromised, the plan must guarantee stable systemic perfusion immediately.
3. What pulmonary blood flow strategy fits the whole pathway?
• Band physiology: protects lungs if systemic outflow is acceptable and remains surveilled.
• Shunt physiology: accepts shunt dependence to secure systemic outflow when obstruction is significant.
4. What best protects the Fontan endgame?
• Early avoidance of systemic outflow obstruction is not optional—it is foundational to a low-burden path to BDG/Fontan. [3,4,7]

6) Follow-up after Arch repair + PAB

Because SAS may declare itself over time (and sometimes after banding), surveillance should be explicit and proactive:

• Outlet pathway trend (BVF/interventricular connection): evolving restriction, Doppler acceleration, turbulence, ventricular hypertrophy patterns
• Systemic perfusion tolerance: growth trajectory, feeding tolerance, intermittent low-output signals
• Stage planning: if SVOTO is trending worse, decide early whether Stage II should incorporate direct SAS relief or DKS (often paired with BDG when feasible)

References

[1] Jonas RA, Castaneda AR, Lang P. Single ventricle (single- or double-inlet) complicated by subaortic stenosis: surgical options in infancy. Ann Thorac Surg. 1985;39(4):361-366. (PubMed)

[2] Webber SA, LeBlanc JG, Keeton BR, Salmon AP, Sandor GG, Lamb RK, Monro JL. Pulmonary artery banding is not contraindicated in double inlet left ventricle with transposition and aortic arch obstruction. Eur J Cardiothorac Surg. 1995;9(9):515-520. (PubMed)

[3] Chang YH, Kim WH, Lee JY, Kim SJ, Lee C, Hwang SW, Sung SC. Pulmonary artery banding before the Damus-Kaye-Stansel procedure. Pediatr Cardiol. 2006;27(5):594-599. (PubMed)

[4] Tchervenkov CI, Shum-Tim D, Béland MJ, Jutras L, Platt R. Single ventricle with systemic obstruction in early life: comparison of initial pulmonary artery banding versus the Norwood operation. Eur J Cardiothorac Surg. 2001;19(5):671-677. (PubMed)

[5] Kalustian AB, et al. Comparing palliation strategies for single-ventricle anatomy with transposed great arteries and systemic outflow obstruction. JTCVS Tech. 2023;21:149-177. (PubMed)

[6] Yurdakök O, Çiçek M, Korun O, Altın FH, Biçer M, Altuntas Y, et al. The choice of palliative arterial switch operation as an alternative for selected cases in a single center: Experience and mid term results. J Card Surg. 2021;36(6):1979-1984. (PubMed)

[7] Karl TR, Watterson KG, Sano S, Mee RB. Operations for subaortic stenosis in univentricular hearts. Ann Thorac Surg. 1991;52(3):420-427; discussion 427-428. (PubMed)

[8] Schwartz ML, Gauvreau K, del Nido P, Mayer JE, Colan SD. Long-term predictors of aortic root dilation and aortic regurgitation after arterial switch operation. Circulation. 2004;110(11 Suppl 1):II128-II132. (PubMed)

[9] Baba K, Kotani Y, Chaturvedi R, van Arsdell GS, Caldarone CA, et al. Hybrid versus Norwood strategies for single-ventricle palliation. Circulation. 2012;126(11 Suppl 1):S123-S131. (PubMed)

[10] Rahkonen O, Chaturvedi RR, Benson L, 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.e2. (PubMed)