The Norwood procedure - does the type of shunt determine outcome?

Comparison of shunt types in the neonatal Norwood procedure for single ventricle

OBJECTIVES

The ideal shunt for pulmonary blood flow, modified Blalock-Taussig shunt (MBTS) or right ventricular-pulmonary artery conduit (RVPAC) is yet to be determined. This study aimed to evaluate outcomes after the Norwood procedure according to the type of shunt.

METHODS

A total of 322 neonates with hypoplastic left heart syndrome and related anomalies who underwent the Norwood procedure at our institution between 2001 and 2019 were divided into MBTS and RVPAC groups and the outcomes after the Norwood procedure were compared between the groups with respect to mortality after each staged procedure.

RESULTS

We identified 322 consequent patients who underwent neonatal Norwood procedure for hypoplastic left heart syndrome (271 patients, 84.2%) and its variant (51 patients, 15.8%). RVPAC was performed in 163 (50.6%) patients and MBTS was performed in 159 (49.4%). There were no differences in the rate of early death (11.0% vs 12.6%, P = 0.69) or late death (7.4% vs 6.9%, P = 0.87) between the 2 groups after the Norwood procedure, and no significant difference in the number of patients who reached bidirectional cavopulmonary shunt (77.9% vs 76.1%, P = 0.69), and there was no difference in mortality after bidirectional cavopulmonary shunt (12.3% vs 7.5%, P = 0.15) or Fontan completion rate (54.0% vs 52.2%, P = 0.42) between the 2 groups. Survival at 0.5, 1, 3 and 6 years after the Norwood procedure was 81.0%, 73.8%, 67.9% and 67.0% in patients with RVPAC and 77.1%, 73.3%, 69.1% and 67.9% in patients with MBTS. There was no significant difference in the survival between the 2 groups during the median follow-up of 2.6 (interquartile ranges: 0.3-8.4, maximal 18.8) years (P = 0.97).

CONCLUSIONS

In neonates undergoing the Norwood procedure, our available data of maximal 18.8 years follow-up showed no significant difference in early mortality, inter-stage attritions, or overall survival, between MBTS and RVPAC.

Low-body-perfusion via an arterial sheath reduces inflammation after aortic arch reconstruction surgery

Pediatric cardiac surgeries involving aortic arch reconstruction are complex and require long cardiopulmonary bypass (CPB) times with deep hypothermic circulatory arrest (DHCA). Selective perfusion techniques have been developed to prevent the deleterious consequences of DHCA associated hypoperfusion. The effectivity of low body perfusion through cannulation of the femoral artery with an arterial sheath remains to be elucidated. We compared perfusion and inflammation in patients receiving selective antegrade cerebral perfusion (ACP) only to low body perfusion (LBP) in addition to ACP during DHCA for aortic arch reconstruction surgery. There was no difference in patient characteristics, cardiac pathologies, or performed procedures between ACP and LBP groups. Lactate levels increased after cardiac arrest in both groups. However, lactate levels were lower after 1 h reperfusion, at the end of extracorporeal circulation (ECC), and after surgery in LBP group compared to ACP only. Furthermore, creatinine was increased in ACP group on postoperative day 1 compared to LBP group but no acute kidney injury was observed in any group. IL-6 concentration increased in ACP group, while remained unchanged in LBP group compared to pre surgical values and were significantly lower compared to ACP group on postoperative days 1 and 2. LBP via an arterial sheath during cardiac arrest for aortic arch reconstruction surgery in addition to ACP, improves post ECC tissue perfusion as indicated by lower lactate levels and reduces creatinine levels suggesting milder kidney injury. LBP seems to prevent postoperative inflammation through a reduction in procedural duration or enhanced perfusion and thereby improves the outcome after aortic arch reconstruction surgery.

Goal-directed-perfusion in neonatal aortic arch surgery

Reduction of mortality and morbidity in congenital cardiac surgery has always been and remains a major target for the complete team involved. As operative techniques are more and more standardized and refined, surgical risk and associated complication rates have constantly been reduced to an acceptable level but are both still present. Aortic arch surgery in neonates seems to be of particular interest, because perfusion techniques differ widely among institutions and an ideal form of a so called "total body perfusion (TBP)" is somewhat difficult to achieve. Thus concepts of deep hypothermic circulatory arrest (DHCA), regional cerebral perfusion (RCP/with cardioplegic cardiac arrest or on the perfused beating heart) and TBP exist in parallel and all carry an individual risk for organ damage related to perfusion management, chosen core temperature and time on bypass. Patient safety relies more and more on adequate end organ perfusion on cardiopulmonary bypass, especially sensitive organs like the brain, heart, kidney, liver and the gut, whereby on adequate tissue protection, temperature management and oxygen delivery should be visualized and monitored.

Congenital heart surgeon's technical proficiency affects neonatal hospital survival

OBJECTIVE

Risk factors for mortality after neonatal cardiac surgery have been seldom studied. We sought to identify contemporary risk factors for mortality and the impact of surgical technical performance on surgical outcomes after neonatal cardiac surgery.

METHODS

We conducted a matched case-control study comparing 56 neonates who died after cardiac surgery (2002-2008) with 56 survivors matched by surgical procedure and year of surgery. Surgical efficacy for repair or palliation was graded using a reliable simple surgical technical score. Patient and surgical characteristics were compared for the survivors and nonsurvivors using paired analyses.

RESULTS

There was no significant difference between patients who died and their matched controls in terms of age, Aristotle score, Risk Adjustment in Congenital Heart Surgery-1 category, and single versus biventricular repair. When compared with survivors, patients who died were more likely to be premature (41% vs 5%, P < .001), to weigh less than 2.5 kg (25% vs 9%, P = .05), and to have inadequate surgical repair or palliation (55% vs 9%, P < .001). Cardiopulmonary bypass time was longer for the patients who died (median, 159 vs 133 minutes, P = .002). Highest postoperative lactate (median, 9.0 vs 6.0, P < .001), use of extracorporeal membrane oxygenation (71% vs 13%, P < .001), and reoperation during the same admission (75% vs 2%, P < .001) were also associated with death. In multivariable analysis, inadequate surgical repair or palliation (odds ratio, 11, P = .02) and need for postoperative extracorporeal membrane oxygenation (odds ratio, 5.1, P = .009) were the only risk factors associated with hospital death.

CONCLUSIONS

Our study highlights the need for optimal technical performance to minimize neonatal deaths. This has important implications when sustaining or developing a pediatric cardiac program.

Norwood with right ventricle-to-pulmonary artery conduit is more effective than Norwood with Blalock-Taussig shunt for hypoplastic left heart syndrome: mathematic modeling of hemodynamics

OBJECTIVE

The introduction of right ventricle to pulmonary artery (RV-PA) conduit in the Norwood procedure for hypoplastic left heart syndrome resulted in a higher survival rate in many centers. A higher diastolic aortic pressure and a higher mean coronary perfusion pressure were suggested as the hemodynamic advantage of this source of pulmonary blood flow. The main objective of this study was the comparison of two models of Norwood physiology with different types of pulmonary blood flow sources and their hemodynamics.

METHOD

Based on anatomic details obtained from echocardiographic assessment and angiographic studies, two three-dimensional computer models of post-Norwood physiology were developed. The finite-element method was applied for computational hemodynamic simulations. Norwood physiology with RV-PA 5-mm conduit and Blalock-Taussig shunt (BTS) 3.5-mm shunt were compared. Right ventricle work, wall stress, flow velocity, shear rate stress, energy loss and turbulence eddy dissipation were analyzed in both models.

RESULTS

The total work of the right ventricle after Norwood procedure with the 5-mm RV-PA conduit was lower in comparison to the 3.5-mm BTS while establishing an identical systemic blood flow. The Qp/Qs ratio was higher in the BTS group.

CONCLUSIONS

Hemodynamic performance after Norwood with the RV-PA conduit is more effective than after Norwood with BTS. Computer simulations of complicated hemodynamics after the Norwood procedure could be helpful in establishing optimal post-Norwood physiology.