Norwood Operation — Circulatory Arrest and Antegrade Cerebral Perfusion (ACP)

Date
October 8, 2025
URL
https://x.com/WithAScalpel/status/1975886730705215947
Categories
HLHSSingle VentricleCardiac Surgery

Norwood Operation — Circulatory Arrest and Antegrade Cerebral Perfusion (ACP)

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Operative context and objectives

In first-stage palliation for HLHS, this phase connects full CPB to arch reconstruction while (1) protecting brain and myocardium, (2) ensuring unobstructed atrial-level mixing, and (3) setting up a reliable RV–PA conduit. Programs may execute the arch under selective cerebral perfusion with no global arrest by combining innominate artery perfusion with distal body perfusion, but most centers use a brief arrest window followed by ACP to balance exposure and organ protection [1, 2].

Stepwise sequence (with rationale)

  1. Controlled flow-down and vascular control

    2. Gradually reduce CPB flow while snaring the descending aorta, then the left subclavian, left common carotid, and distal innominate. This converts the arch to a small, closed reservoir, limits competitive runoff, and simplifies a bloodless transition to arrest/ACP.

  2. Cardioplegic arrest

    3. Deliver cold blood cardioplegia via the arterial line after the arch is isolated to achieve rapid, homogeneous arrest. The quiet, bloodless field enables precise intracardiac work and reduces intracardiac air.

  3. Short global arrest for intracardiac maneuvers

    4. Pause flow briefly to:

    • Enlarge the ASD until truly nonrestrictive, avoiding post-bypass pulmonary venous hypertension.

    • Make the right ventriculotomy and mark the proximal RV–PA conduit site while the heart is motionless.

    Use a pump sucker for blood clearance; temporarily clamp or remove venous cannulae if they obstruct exposure.

  4. Transition to ACP

    5. Open the distal innominate and restart selective antegrade cerebral perfusion. Evidence supports ACP flows ~30–50 mL/kg/min, right arm/brachial MAP ~35–45 mmHg, hematocrit ~30–40%, and systemic temperature 18–28 °C, titrated to bilateral cerebral oximetry trends; flows <30 mL/kg/min risk inadequate cerebral delivery [3–5]. Direct cannulation or a short graft on the innominate are both acceptable techniques in neonates [6].

  5. Ductal excision and distal control

    6. With ACP running, excise ductal tissue completely. If exposure requires, divide the descending aorta and later re-anastomose posteriorly after ductal clearance to remove shelves that predispose to posterior arch obstruction.

  6. RV–PA conduit completion (program-dependent)

    7. Finish the proximal RV–PA anastomosis either during the initial arrest window or after arch work, depending on team preference and physiology. A short, straight, untwisted course minimizes early gradient and late PA distortion. (The RV–PA conduit is an accepted alternative to a modified BT shunt and was the subject of the SVR randomized trial program) [2, 8].

Technical details that matter

  • Order and tension of snares. Proceed distal→proximal (descending → LSA → LCC → distal innominate) to prevent back-bleeding and ease the switch to ACP.
  • Myocardial protection. Plan the shortest effective arrest window; redose only if needed.
  • ASD enlargement. Leave no “trap-door” flap; restriction here drives pulmonary venous hypertension and low output.
  • RVOT incision and conduit angle. Site away from septal band/infundibular trabeculations; aim toward the mid-left PA for a gentle curve; avoid oversizing and excessive length.
  • Air and particulate control. Arrest-then-ACP sequencing lowers cerebral air risk; de-air the innominate meticulously.
  • Cerebral monitoring. Use bilateral cerebral NIRS as a trend monitor alongside right-arm pressure to guide ACP; promptly troubleshoot falls (kinked innominate, over-tight snares, cannula malposition) [7].

Common pitfalls and preventions

  • Inadequate ASD → pulmonary venous hypertension and difficult wean. Prevention: make it truly unrestrictive at first pass.
  • Residual ductal tissue → posterior arch shelf and recurrent obstruction. Prevention: complete ductal excision before posterior re-anastomosis.
  • Cerebral malperfusion on ACP → NIRS drop/flat arterial tracing. Prevention: confirm luminal patency, relieve snare tension, verify cannula; target flows within evidence-based ranges [4, 5].
  • Conduit malorientation → early RV–PA gradient/kink. Prevention: short, straight, untwisted path; reassess after rewarming with a full heart.
  • Prolonged arrest → edema and low output. Prevention: front-load exposure, script steps, and time the arrest; consider brief low-flow interludes or redose if needed.

Programmatic variations (accepted alternatives)

  • Temperature strategy. Deep vs moderate hypothermia; several series report excellent outcomes with moderate hypothermia plus ACP and no deep hypothermic circulatory arrest when dual-cannulation strategies maintain lower-body flow [1, 3].
  • Cannulation strategy. Direct innominate cannulation vs short graft; both are feasible in neonates and support stable ACP [6].
  • Pulmonary blood-flow source. mBT shunt constructed before bypass (classic) vs RV–PA conduit; center-level preferences vary and have been rigorously evaluated in the SVR program [2, 8].

Key takeaways

  • A deliberate, timed transition—flow-down → short arrest for intracardiac work → ACP-supported arch reconstruction—anchors safe Norwood execution.
  • Outcomes hinge on unrestricted ASD, complete ductal excision, and well-oriented RV–PA conduit.
  • ACP should be individualized but data favor flows ≥30–40 mL/kg/min with NIRS-guided titration, right-arm MAP ~35–45 mmHg, hematocrit ~30–40%, and moderate hypothermia, with vigilant troubleshooting of cerebral perfusion signals [3–5, 7].

References

[1] Imoto Y, Kado H, Shiokawa Y, et al. Norwood procedure without circulatory arrest. Ann Thorac Surg. 1999;68(2):573-577. PubMed

[2] Tchervenkov CI, Tahta SA, Shum-Tim D, Cecere R, Béland MJ. Norwood operation without circulatory arrest. Ann Thorac Surg. 2000;70(5):1687-1690. annalsthoracicsurgery.org

[3] Oppido G, Napoleone CP, Turci S, et al. Moderately hypothermic cardiopulmonary bypass and low-flow antegrade selective cerebral perfusion in neonatal aortic arch surgery. Ann Thorac Surg. 2006;82(1):226-232. annalsthoracicsurgery.org+1

[4] Fraser CD Jr. Principles of antegrade cerebral perfusion during arch reconstruction in newborns and infants. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2008;11(1):61-68. pmc.ncbi.nlm.nih.gov+1

[5] Gupta B, Bavaria JE, Desai ND, et al. Antegrade cerebral perfusion at 25 °C for arch reconstruction: A review of strategy and outcomes. Transl Pediatr. 2016;5(3):170-182. tp.amegroups.org

[6] Amir G, Frenkel G, Erez E, et al. Direct innominate artery cannulation for antegrade cerebral perfusion in neonates and infants. Ann Thorac Surg. 2013;95(2):672-676. annalsthoracicsurgery.org

[7] Zaleski KL, DiNardo JA, Zurakowski D, et al. Near-Infrared Spectroscopy in Pediatric Congenital Heart Disease: A Review. Prog Pediatr Cardiol. 2020;58:101257. PubMed

[8] Ohye RG, Sleeper LA, Mahony L, et al. Design and rationale of a randomized trial comparing the right ventricle-to-pulmonary artery conduit with the modified Blalock–Taussig shunt in the Norwood procedure. J Thorac Cardiovasc Surg. 2008;136(4):968-975. sciencedirect.com

Notes: Where numerical targets are provided, they synthesize ranges reported across [3–5]; NIRS is emphasized as a trend tool rather than an absolute measure [7]. Programmatic options to avoid full circulatory arrest and to use RV–PA conduit shunting reflect techniques described in [1, 2, 8].