Tetralogy of Fallot (TOF) — #5 RVOT Muscle Resection

In classic TOF, RVOT obstruction is primarily a muscle-and-geometry problem: hypertrophied infundibular musculature superimposed on a malaligned outlet septum. The operative goal is not simply “debulking muscle,” but reconstructing a smooth, capacious outflow pathway that minimizes turbulence and late RV loading—while preserving pulmonary valve competence whenever anatomy allows. Contemporary outcome data increasingly support valve-sparing approaches when feasible, with lower pulmonary regurgitation burden compared with transannular patch strategies. [1]

1) Operative objective: “Relieve RVOT obstruction without creating new problems”

A durable RVOT myectomy/muscle resection should achieve two endpoints:

1. Effective relief of fixed + dynamic obstruction
• Remove obstructing bundles/trabeculations and contour the infundibulum.
• Eliminate subvalvar “shelves” (often at the ventriculo-infundibular fold and infundibular septum) that can recreate a residual gradient.
2. Preservation of structures that determine late outcomes
• Pulmonary valve/annulus when feasible (bias toward valve-sparing). [1,3,4]
• RV free wall integrity (avoid over-resection → thinning/aneurysm/dyskinesia).
• Coronary safety, especially when an anomalous coronary crosses the RVOT.
• Septal and VSD patch edge integrity (avoid iatrogenic VSD leak or conduction injury).

2) Landmark anatomy: what must be mapped before cutting

RVOT resection is safer and more complete when the surgeon “names the terrain”:

• Septomarginal trabeculation (septal band) & moderator band complex
• Frequently part of the obstructing architecture; resect selectively—do not destabilize RV geometry.
• Ventriculo-infundibular fold (VIF)
• A muscular ridge at the RV body–infundibulum transition; a common site for residual subvalvar obstruction if left as a “step.”
• Infundibular (outlet) septum
• Malalignment/hypertrophy contributes to narrowing and flow eccentricity.
• Anterior RVOT free wall
• Resection here must be controlled: enough to open the tract, not enough to weaken it.
• Pulmonary valve region
• The functional endpoint: the RVOT must be unobstructed up to the hinge points/commissures without sacrificing leaflet motion.

3) Contemporary operative strategy: staged, multi-window relief (transatrial + transpulmonary)

Many centers favor a transatrial–transpulmonary pathway to maximize subvalvar relief while minimizing ventriculotomy and supporting valve-sparing when possible. [3,4,7]

Step A — Transatrial (through RA/tricuspid valve): “debulk from inside-out”

Goal: remove obstructing muscle bundles within the RV and infundibulum, working toward the pulmonary valve.

Key actions

• Identify and shave obstructing trabeculations/bundles (often including “coarse” RV muscle).
• Use an incremental technique: shave → reassess → repeat (avoid a single aggressive bite).
• Keep orientation: open the pathway toward the pulmonary valve, not laterally into free wall.

Pearls

• Think “smooth channel,” not “maximum resection.”
• Preserve the RV architectural scaffold (avoid unnecessary disruption near the moderator band complex).

Step B — Transpulmonary (through pulmonary valve/RVOT): “finish the last millimeters”

Goal: complete relief at the subvalvar–valvar junction and refine the VIF/infundibular septum/anterior RVOT contributions.

Key actions

• Under direct transpulmonary vision, contour:
• residual subvalvar ridges at/near the VIF
• obstructing prominence of the infundibular septum
• hypertrophy along the anterior RVOT as needed.
• Confirm there is no remaining “shelf” immediately beneath the valve that will behave like annular stenosis post-repair.

Technique variants (anatomy-driven)

• Infundibulum-sparing philosophies emphasize preserving RV infundibular integrity while achieving adequate lumen—classically framed as RVIS concepts. [2]
• Limited incision designs (e.g., T-shaped infundibulotomy) have been reported to facilitate valve-sparing exposure and contouring while limiting RV injury. [5]

4) Valve-sparing versus transannular augmentation: decision principles (not ideology)

The RVOT strategy should be chosen by physiology and anatomy, not by a single preferred technique.

Valve-sparing is favored when:

• Subvalvar obstruction can be adequately relieved without forcing an undersized annulus to carry the entire gradient.
• Leaflets are mobile and commissures can be optimized without creating prohibitive stenosis.
• The postoperative physiology will not require excessive RV systolic pressure.

Evidence synthesis suggests valve-sparing approaches are associated with less pulmonary regurgitation and favorable early outcomes compared with transannular patch repair, although the clinical trade-off can be a higher vigilance for residual obstruction in some series. [1,4]

Transannular enlargement (or alternative augmentation) becomes necessary when:

• Annulus/valve tissue is truly inadequate despite maximal safe subvalvar relief.
• Acceptable RV pressure and forward flow cannot be achieved without enlargement.

5) “Do not injure” checklist (high-yield intraoperative constraints)

Throughout RVOT resection, explicitly protect:

• Ventricular septum & conduction axis
• Avoid deep septal bites; prevent new septal defects and conduction injury.
• RV free wall
• Over-resection risks thinning, dyskinesia, and aneurysmal remodeling.
• Coronary arteries
• Assume anomalous coronary anatomy until confirmed; if a coronary crosses the RVOT, avoid risky incisions and rely on transatrial/transpulmonary relief and tailored reconstruction.
• VSD patch edge / outlet region
• Do not undermine the patch margin or create a leak line at the RVOT–VSD interface.

6) Adequacy of repair: how to know you are “done”

A practical intraoperative endpoint combines anatomy + physiology:

1. Anatomic continuity
• RV body → infundibulum → subvalvar region should appear as a single lumen with no steps or shelves.
2. Valve-level function
• Leaflets should remain mobile; relief should not be achieved by leaflet injury or distortion.
3. Hemodynamic/echo confirmation
• Intraoperative echo is used to confirm:
• no significant residual RVOT obstruction,
• acceptable pulmonary valve function (especially if valve-sparing),
• no new defects (residual VSD, RVOT distortion).

Common pitfall: a residual subvalvar ridge (often VIF/infundibular septum) that looks acceptable visually but later declares itself as a persistent gradient—one reason multi-window assessment has remained valuable. [4,7]

7) Why this step matters long-term

Long-term outcomes after TOF repair are shaped by the balance between residual RVOT obstruction and pulmonary regurgitation, because both can drive RV remodeling, arrhythmia risk, and the future need for reintervention. [8,9] “Optimal” contemporary management therefore emphasizes:

• meticulous subvalvar relief (to prevent late obstruction),
• disciplined RV preservation (to avoid ventriculotomy-related injury when possible),
• and thoughtful strategies to limit pulmonary regurgitation burden when anatomy permits. [1,3,9,10]

References

[1] Martins RS, Fatimi AS, Mahmud O, Qureshi S, Nasim MT, Virani SS, et al. Comparing clinical and echocardiographic outcomes following valve-sparing versus transannular patch repair of tetralogy of Fallot: a systematic review and meta-analysis. Interdiscip Cardiovasc Thorac Surg. 2024;39(1):ivae124.

[2] Morales DL, Zafar F, Fraser CD Jr. Tetralogy of Fallot repair: the Right Ventricle Infundibulum Sparing (RVIS) strategy. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2009;2009:54-58.

[3] Stewart RD, Backer CL, Young L, Mavroudis C. Tetralogy of Fallot: results of a pulmonary valve-sparing strategy. Ann Thorac Surg. 2005;80(4):1431-1438.

[4] Bové T, François K, Van De Kerckhove K, Panzer J, De Groote K, De Wolf D, et al. Assessment of a right-ventricular infundibulum-sparing approach in transatrial-transpulmonary repair of tetralogy of Fallot. Eur J Cardiothorac Surg. 2012;41(1):126-133.

[5] Leobon B, Cousin G, Hadeed K, Breinig S, Alacoque X, Berthomieu L, et al. Tetralogy of Fallot: T-shaped infundibulotomy for pulmonary valve-sparing procedure. Interact Cardiovasc Thorac Surg. 2022;34(3):488-491.

[6] Arafat AA, Elatafy EE, Elshedoudy S, Zalat M, Abdallah N, Elmahrouk A. Surgical strategies protecting against right ventricular dilatation following tetralogy of Fallot repair. J Cardiothorac Surg. 2018;13(1):14.

[7] Alexiou C, Chen Q, Galogavrou M, Gnanapragasam J, Salmon AP, Keeton BR, et al. Repair of tetralogy of Fallot in infancy with a transventricular or a transatrial approach. Eur J Cardiothorac Surg. 2002;22(2):174-183.

[8] Padalino MA, Pradegan N, Azzolina D, Galletti L, Pace Napoleone C, Agati S, et al. The role of primary surgical repair technique on late outcomes of Tetralogy of Fallot: a multicentre study. Eur J Cardiothorac Surg. 2020;57(3):565-573.

[9] van der Ven JPG, van den Bosch E, Bogers AJCC, Helbing WA. Current outcomes and treatment of tetralogy of Fallot. F1000Res. 2019;8:F1000 Faculty Rev-1530.

[10] Vanderlaan RD, Barron DJ. Optimal Surgical Management of Tetralogy of Fallot. CJC Pediatr Congenit Heart Dis. 2023;2(6 Pt A):352-360.