Norwood Operation — Preparation and Initiation of CPB

Date
October 7, 2025
URL
https://x.com/WithAScalpel/status/1975538470014607851
Categories
Cardiac SurgeryHLHSSingle Ventricle

Norwood Operation — Preparation and Initiation of Cardiopulmonary Bypass

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Operative intent

The preparatory phase of the Norwood operation establishes safe cardiopulmonary bypass (CPB), stabilizes the systemic–pulmonary flow balance, and optimizes exposure for arch reconstruction and creation of a controlled pulmonary blood-flow (PBF) source. Core priorities are: (1) reliable arterial access that avoids manipulating the diminutive ascending aorta; (2) venous drainage that preserves atrial exposure; (3) proactive PBF control to prevent coronary and systemic steal; and (4) meticulous branch pulmonary artery (PA) protection in anticipation of an RV–PA conduit [1–3].

Monitoring and setup

  • Standard neonatal monitoring with pre- and post-ductal oximetry, an invasive arterial line (umbilical or radial), central venous pressure, cerebral and somatic NIRS, and core temperature.
  • Broad-spectrum antibiotics, systemic heparinization per protocol, and secure endotracheal tube fixation to tolerate frequent head/neck manipulation.
  • Prior to CPB, low FiO₂ and permissive hypercapnia can temper PBF in shunt-dependent neonates; vasoactives are titrated to maintain systemic perfusion pressure and cerebral NIRS targets [1,2].

Exposure and cannulation strategy

  1. Median sternotomy and wide pericardiotomy. Pericardial stay sutures provide unobstructed exposure of the great vessels and PA confluence.
  2. Arterial inflow via the innominate artery. A short ringed PTFE graft (≈3.0–3.5 mm) is anastomosed end-to-side to the innominate artery and used for arterial cannulation. This approach avoids ascending aortic manipulation, enables a rapid switch to selective antegrade cerebral perfusion (ACP), and preserves the arch field [1,3]. (Across centers, both direct and graft-assisted innominate cannulation are used with comparable cerebral perfusion metrics when carefully managed [3].)
  3. Venous drainage. A single right-atrial two-stage cannula provides effective drainage while maintaining room for atrial septectomy later in the operation.
  4. Pulmonary blood-flow control. An RPA snare attenuates PBF and supports systemic pressure before bypass; once CPB is established, the PDA is ligated to eliminate competitive runoff to the lungs and protect coronary perfusion [2,4].

Initiation of CPB and cooling

Full CPB is instituted via the innominate graft and right-atrial cannulation. Cooling proceeds to deep hypothermia (≈18 °C) to enable safe arch work and cerebral protection. During cooling, the neck vessels and proximal descending aorta are fully mobilized, and the ACP pathway is confirmed. Many programs use ACP (regional cerebral perfusion) to reduce or avoid prolonged circulatory arrest during arch reconstruction; others employ continuous myocardial perfusion strategies during arch work to further protect the heart [1,2].

Pulmonary artery management for an RV–PA conduit (Sano modification)

  1. Main PA division. In aortic atresia anatomy, the main PA is transected just below the bifurcation with vigilant protection of the pulmonary valve proximally and the left PA orifice distally.
  2. Confluence plasty for the conduit landing. The distal main PA/PA confluence is enlarged with a patch (cryopreserved homograft or autologous pericardium) to create a generous, circular orifice sized for a 5–6 mm ringed PTFE conduit. Both branch PAs are probed to confirm patency and exclude distortion [4–6].
  3. Geometric planning. The intended Ao–PA “kissing point” (where the reconstructed neoaorta will course near the PA confluence) and the RV insertion site are pre-marked. This reduces future kinking, minimizes energy loss, and preserves a straight, laminar conduit trajectory under the sternum [4–6].
Practice variation. Conduit size (4–6 mm), material (ringed vs plain), and routing relative to the neoaorta vary across centers; these choices trade off diastolic runoff, gradients, and sternum clearance and are individualized to neonatal size, PA reactivity, and coronary reserve [4–6].

Transition to cerebral protection

At target temperature and after arch preparation, ACP is instituted via the innominate graft (perfusing the right subclavian and right common carotid). Venous drainage is maintained; the lower body is placed in circulatory arrest as required for arch opening and reconstruction. Regional cerebral perfusion strategies (innominate inflow ± adjunct descending aortic cannulation) are well described and permit controlled cerebral pressures during arch work [1].

Technical pearls and pitfalls

  • Early RPA snare and PDA ligation. In ductal-dependent single-ventricle physiology, unrestricted PBF steals from coronary and systemic beds; timely control of PBF stabilizes diastolic pressure and coronary flow [2,4].
  • Protect the LPA. The LPA orifice is vulnerable during main-PA transection and confluence patching. Off-axis arteriotomy or undersized plasty creates turbulence and distal hypoperfusion; fashion a round, nonrestrictive landing zone sized to the intended conduit [4–6].
  • Plan conduit geometry. Pre-marking the RV entry and path avoids heel–toe malalignment, sternal compression, and crossing/kinking against the neoaorta [4–6].
  • Preserve bailout options. The innominate graft used for arterial inflow can be repurposed as a systemic-to-PA shunt in rare rescue scenarios [3–5].

Variations and institutional preferences

  • Arterial cannulation. Direct vs graft-assisted innominate cannulation and ACP details vary; with careful technique, cerebral perfusion goals are achievable with either approach [1,3].
  • Conduit size selection. A 5 mm conduit is common in average-weight neonates; 6 mm reduces gradients but may increase diastolic runoff, whereas 4–5 mm may be favored in very small infants or reactive PAs—tailor to coronary reserve, PA reactivity, and anticipated ventilation strategy after separation from CPB [4–6].
  • Patch choice. Homograft patches resist dilatation and handle well; autologous pericardium is readily available but may thicken or calcify—either is acceptable when the orifice is generous and geometry optimized [5,6].
  • Program-level variation. Beyond cannulation and conduit choices, centers differ in perfusion variables, arch reconstruction details, and perioperative medication strategies; these practice differences are associated with measurable variation in outcomes across institutions [6–8].

Safety checks before proceeding to arch work

  • Stable systemic arterial pressure and cerebral NIRS with controlled PBF.
  • Secure hemostasis at the innominate graft and PA patch sites.
  • Unobstructed branch PAs on probing/visual inspection.
  • Clearly visible orientation marks for the neoaortic pathway and RV–PA conduit position.

References

[1] Pigula FA, Nemoto EM, Griffith BP, Siewers RD. Regional low-flow perfusion provides cerebral circulatory support during deep hypothermic circulatory arrest for neonatal aortic arch surgery. J Thorac Cardiovasc Surg. 2000;119(2):331-339.

[2] Turek JW, Ohye RG, Walsh MA, et al. Continuous myocardial perfusion during neonatal aortic arch reconstruction: techniques and early results. J Thorac Cardiovasc Surg. 2013;146(6):1462-1468.

[3] Imoto Y, Kado H, Shiokawa Y, Lee Y, Yasui H. Selective cerebral perfusion through the right brachiocephalic artery for aortic arch repair in neonates and infants. Ann Thorac Surg. 2001;71(2):333-338.

[4] Sano S, Ishino K, Kawada M, et al. Right ventricle–pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome. J Thorac Cardiovasc Surg. 2003;126(2):504-509.

[5] Tweddell JS, Hoffman GM, Mussatto KA, et al. Improved survival of patients undergoing Norwood operation: the impact of a dedicated program and regionalization. Circulation. 2002;106(12 Suppl 1):I-82–I-89.

[6] Ohye RG, Sleeper LA, Mahony L, et al.; Pediatric Heart Network Investigators. Comparison of shunt types in the Norwood procedure for single-ventricle lesions. N Engl J Med. 2010;362(21):1980-1992.

[7] Shuhaiber JH, Hurwitz RA, Caldwell RL, Bender HW Jr. Right ventricle-to-pulmonary artery conduit for the Norwood procedure: technical considerations and midterm results. Ann Thorac Surg. 2011;91(2):499-505.

[8] Pasquali SK, Jacobs JP, He X, et al. Variation in outcomes for benchmark operations: an analysis of the Society of Thoracic Surgeons Congenital Heart Surgery Database. Ann Thorac Surg. 2012;94(2):564-571.