A Comparison of the Modified Blalock-Taussig Shunt With the Right Ventricle-to-Pulmonary Artery Conduit

doi:10.1016/j.athoracsur.2010.11.062

The Annals of Thoracic Surgery

Volume 91, Issue 5, May 2011, Pages 1479-1485

Presented at the Fifty-sixth Annual Meeting of the Southern Thoracic Surgical Association, Marco Island, FL, Nov 4–7, 2009.

https://doi.org/10.1016/j.athoracsur.2010.11.062 Get rights and content

Background

This study compared the modified Blalock-Taussig (MBT) shunt with the right ventricle-to-pulmonary artery (RVPA) conduit with respect to outcome and PA growth.

Methods

PA growth was assessed in 19 MBT patients and in 15 RVPA patients before stage 2 palliation for hypoplastic left heart syndrome. The RVPA was done with a ringed Gore-Tex tube (W. L. Gore and Assoc, Flagstaff, AZ) at each anastomosis.

Results

The two cohorts had similar pre-Glenn demographic and hemodynamic data. No patient required transcatheter or surgical intervention on the shunt or PAs after stage 1 palliation. The branch PA growth was better in RVPA (McGoon ratio: MBT, 1.5 ± 0.2 vs RVPA, 2.0 ± 0.6; p < 0.003) and was significantly more balanced (right-to-left PA area ratio: MBT, 1.5 ± 0.5 vs RVPA, 0.9 ± 0.6; p = 0.002). The Nakata index trended higher in RVPA (MBT, 242A ± 90 mm²/m² vs RVPA, 267 ± 95 mm²/m², p = 0.2). After stage 2 palliation, oxygen saturation trended higher in the RVPA (81% ± 5%) vs MBT cohort (77% ± 8%, p < 0.08).

Conclusions

The Norwood operation using a RVPA nonvalved conduit is associated with improved branch PA growth.

Section snippets

Patients and Methods

The Institutional Review Board at Saint Louis University approved this study and waived the need for patient consent.

SP1 Mortality

Among the 44 HLHS patients who were operated, there were 8 early deaths: 5 of 26 (19%) MBT patients vs 3 of 18 (17%) RVPA patients (p = 0.4). In the MBT cohort, 1 patient with left recurrent laryngeal nerve paralysis and a gastrostomy tube died 3 weeks postoperatively of aspiration while feeding. Cardiac arrest occurred in 3 additional patients in this cohort and they died at 2, 3, and 7 days postoperatively after suctioning. Extracorporeal membrane oxygenation was used in all 3 patients

Comment

This retrospective, nonrandomized study compares the outcome of a small cohort of patients with HLHS undergoing a MBT shunt or a RVPA conduit as a source of pulmonary blood flow. An important limitation of this report is that the control group (MBT) is historic, and patients in the RVPA cohort were operated on at a later time, and therefore, our results were influenced by a learning curve that involved all physicians and nurses caring for these complex neonates. This is reflected in our

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Cited by (18)

Evolution of the Norwood operation outcomes in patients with late presentation
2020, Journal of Thoracic and Cardiovascular Surgery
We present the evolution of Norwood operation outcomes and practice pattern changes over 15 years from a single institution in Saudi Arabia. We intended to identify time trends in patient selection, procedural details, and outcome predictors over time.
Patients who underwent a Norwood operation (n = 145) between 2003 and 2018 with the use of a Blalock–Taussig shunt (BT group; n = 72), right ventricle to pulmonary artery shunt (Sano group; n = 66), or a primary cavopulmonary shunt (CPS group; n = 7) were included. The study outcomes were operative mortality, long-term survival, and multistate transition to CPS, Fontan, and death.
Median age was 29 days. Predictors of operative mortality were lower weight (P = .026), and longer bypass time (P = .014), whereas age, and type of shunt were not. Predictors of improved long-term survival were greater weight at operation (P = .0016), later era (P = .006), and shorter bypass time (P = .001). The multistate model revealed that patients with lower weight were more likely to undergo Sano versus BT (P < .001), and if BT was chosen in such patients, they were more likely to die (P = .027). The likelihood of receiving Sano shunt was 3-fold greater in the recent era (P = .003).
Improved outcomes of the Norwood operation are evident in the recent era and with Sano shunt, especially in patients of smaller weight. Late presentation or older age is not a contraindication to Norwood operation. The incorporation of a primary CPS at stage one operation is feasible in selected patients.
Long term survival of hypoplastic left heart syndrome infants: Meta-analysis comparing outcomes from the modified Blalock–Taussig shunt and the right ventricle to pulmonary artery shunt
2018, International Journal of Cardiology
Citation Excerpt :
The current analysis is the first to systematically synthesise early outcomes between the two shunt groups, suggesting that early survival was inferior for the mBTS group compared to the RVPAS group. Most previous single centre studies have favoured the RVPAS in the short term [9,16,18,33,36,37,42,43,46], but very few have reported statistically significant differences. Furthermore, one previous meta-analysis found comparable outcomes between the two groups, but due to duplicate bias, the results must be regarded with caution [13].
Stage 1 palliation of hypoplastic left heart syndrome (HLHS) involves the Norwood procedure combined with a modified Blalock–Taussig shunt (mBTS) or right ventricle to pulmonary artery shunt (RVPAS). Short-term survival has been described previously, whereas longer-term outcomes remain a subject of debate. This meta-analysis aimed to describe the short and long-term survival outcomes of these two shunts, and explore factors that might influence survival.
Medline, Cochrane Libraries and EMBASE were systematically searched, and 32 studies were included for statistical synthesis, comprising 1348 mBTS and 1258 RVPAS patients.
While early in-hospital survival was superior in the RVPAS group (RR = 1.5, p < 0.05, 95% CI: 1.21–1.85), this difference was lost from 2 years post-stage 1 palliation (RR = 0.91, p > 0.05, 95% CI: 0.79–1.04), and maintained unchanged up to 6 years. This shift in survival was also reflected in inter-stage survival, with superior RVPAS outcomes between stage 1 and 2 (RR = 1.62, p < 0.05, 95% CI: 1.39–1.88), and equivalent outcomes between stage 2 and 3. Potential contributors to this included a significantly higher rate of pulmonary artery stenosis in the RVPAS group and an increased requirement for shunt re-intervention in this group prior to stage 2.
Despite early advantages, RVPAS and mBTS for palliation of hypoplastic left heart syndrome produced comparable long-term survival. The RVPAS patients experienced more pulmonary artery stenosis and requirement for shunt re-intervention. The impact of shunt type on quality and survival with a Fontan is yet to be assessed.
Uncontrolled Antegrade Pulmonary Blood Flow and Delayed Fontan Completion after the Bidirectional Glenn Procedure: Real-World Outcomes in China
2016, Annals of Thoracic Surgery
Given the low rate of Fontan completion, an aggressive policy for maintaining antegrade pulmonary blood flow (AnPBF) during the bidirectional Glenn procedure (BDG) was developed for the functional single ventricle.
From 2008 to 2013, 294 patients who underwent the BDG were divided into two groups: group 1 (uncontrolled AnPBF, n = 270) and group 2 (controlled AnPBF, n = 24). Pulmonary artery banding was performed because of the high central venous pressure in group 2. In group 1, the patients who underwent BDG from 2008 to 2012 were further divided into group DF (delayed Fontan completion, n = 109) and group FC (Fontan completion, n = 42).
The Fontan completion rate was 16.3%, and the average interval time was 2.2 ± 1.1 years. The delay of Fontan completion did not reduce body weight gain or the survival rate. Furthermore, oxygen saturation was slightly reduced in group DF. Although no impairments of heart function were observed, the uncontrolled AnPBF in group DF resulted in an increase in ventricular end-diastolic diameter and aggravation of atrioventricular valve regurgitation over 24 months after BDG. Logistic regression analysis revealed that systemic right ventricular morphology was a risk factor for the aggravation of valve regurgitation.
The low Fontan achievement rate is a critical issue in China. Although the patients with delayed Fontan completion exhibited an acceptable survival rate and acceptable body weight gain, uncontrolled AnPBF was associated with ventricular enlargement and aggravation of valve regurgitation. Strategies for improving the Fontan completion rate in China should be explored and could benefit outcomes.
Evaluation of cerebral oxygenation and perfusion with conversion from an arterial-to-systemic shunt circulation to the bidirectional Glenn circulation in patients with univentricular cardiac abnormalities
2015, Journal of Cardiothoracic and Vascular Anesthesia
Citation Excerpt :
Comparison of the effect of shunt type on cerebral perfusion and oxygenation at the time of the BDG operation found that rSO2 and CBFV were similar in the MBT shunt and RV-PA conduit groups preoperatively and at discharge. Although there were variations in the hemodynamic profile between the 2 shunt types at the time of stage-2 reconstruction,8,9,21,22 this finding was not surprising because no difference in early postoperative CBFVs and rSO2 between those subjects with an MBT shunt versus an RV-PA conduit was observed previously.7 Similar changes were observed in each shunt group with induction of anesthesia, except for VD, which decreased only in the MBT group (p = 0.03).
Superior vena cava pressure after the bidirectional Glenn operation usually is higher than that associated with the preceding shunt-dependent circulation. The aim of the present study was to determine whether the acute elevation in central venous pressure was associated with changes in cerebral oxygenation and perfusion.
Single-center prospective, observational cohort study.
Academic children’s hospital.
Infants with single-ventricle lesions and surgically placed systemic-to-pulmonary artery shunts undergoing the bidirectional Glenn operation.
Near-infrared spectroscopy and transcranial Doppler sonography were used to measure regional cerebral oxygen saturation and cerebral blood flow velocity.
Mean differences in regional cerebral oxygen saturation and cerebral blood flow velocity before anesthetic induction and shortly before hospital discharge were compared using the F-test in repeated measures analysis of variance. In the 24 infants studied, mean cerebral oxygen saturation increased from 49%±2% to 57%±2% (p = 0.007), mean cerebral blood flow velocity decreased from 57±4 cm/s to 47±4 cm/s (p = 0.026), and peak systolic cerebral blood flow velocity decreased from 111±6 cm/s to 99±6 cm/s (p = 0.046) after the bidirectional Glenn operation. Mean central venous pressure was 8±2 mmHg postinduction of anesthesia and 14±4 mmHg on the first postoperative day and was not associated with a change in cerebral perfusion pressure (p = 0.35).
The bidirectional Glenn operation in infants with a shunt-dependent circulation is associated with an improvement in cerebral oxygenation, and the lower cerebral blood flow velocity is likely a response of intact cerebral autoregulation.
A reinforced right-ventricle-to-pulmonary-artery conduit for the stage-1 Norwood procedure improves pulmonary artery growth
2015, Journal of Thoracic and Cardiovascular Surgery
To compare early postoperative outcomes, angiographic, and intervention findings and 1-year survival between 2 groups of infant patients: those receiving a standard right-ventricle-to-pulmonary-artery (RV-PA) conduit versus a ring-reinforced RV-PA conduit, in undergoing Norwood stage-1 surgery for hypoplastic left heart syndrome (HLHS). The technique of using such a ring-reinforced graft, placed through a limited ventriculotomy, has theoretic advantages in preserving right ventricular function, compared with the standard technique of RV-PA conduit creation.
This retrospective cohort study was performed between July 2006 and July 2013. A total of 87 patients with HLHS underwent Norwood stage-1 surgery during this period; 48 received a standard nonreinforced RV-PA conduit; 39 received a ring-reinforced conduit. Primary and secondary outcomes were survival and need for cardiac reintervention up to age 12 months.
No difference was found in transplant-free survival by age 12 months (87% ring-reinforced vs 73% nonreinforced, P = .12). The group with the nonreinforced, versus ring-reinforced, grafts had more interventions in the first year (69% vs 35%, respectively; P < .01). Before stage 2, the pulmonary artery pulse pressure was greater in the group with ring-reinforced grafts (9.1 ± 4.1 vs 4.8 ± 3.1 mm Hg, P < .001), with no difference in mean pressure (15.2 ± 3.32 vs 14.3 ± 3.48 mm Hg, P = .27). The corrected pulmonary artery index (Nakata) was greater in the group with ring-reinforced grafts (213 ± 76 vs 134 ± 68 mm²/m², P < .0001).
A ring-reinforced conduit is associated with reduced intervention, as well as higher pulse pressures and improved pulmonary artery growth, in infants undergoing stage-1 palliation for HLHS.
In search of the ideal pulmonary blood source for the norwood procedure: A meta-analysis and systematic review
2014, Annals of Thoracic Surgery
Citation Excerpt :
There was no difference in the ventricular functions (mean ejection fraction or number of patients with more than moderate dysfunction) at the stage 2 procedure in most of the studies. Seven studies [4, 7, 17–19, 22, 29] presented the number of patients who had more than a moderate grade of tricuspid regurgitation at the time of the stage 2 procedure. Moderate to severe tricuspid regurgitation was present in 24% and 31% patients in MBTS and RV-PAS group, respectively; however the difference was not statistically significant (RR, 0.62; 95% CI, 0.32 to 1.22; p < 0.16; Fig 6).
A clear consensus regarding the optimal source of pulmonary blood flow in patients with hypoplastic left heart syndrome undergoing the Norwood procedure is lacking.
A literature search was undertaken to identify relevant articles from 2005 to 2012 using “Norwood, stage 1 palliation,” “Modified Blalock Taussig shunt (MBTS),” “right ventricle-to-pulmonary artery shunt (RV-PAS)” alone or in combination. Three end points were selected: early/stage 1 mortality, interstage mortality, and interstage total/shunt intervention.
A total of 20 articles, including 19 observational studies and 1 randomized trial (MBTS, n = 1,343; RV-PAS, n = 1,028), met the inclusion criteria. Mortality after stage 1 was 22% in the MBTS cohort and 16% in RV-PAS cohort. A pooled analysis showed no difference in early mortality between the two groups (risk ratio [RR], 1.20; 95% confidence interval [CI], 0.99 to 1.45; p = 0.07). On pooling data from contemporary series (similar era) of 8 studies (MBTS, n = 709; RV-PAS, n = 631), to minimize variability in surgical and postoperative management practices, early mortality in both cohorts was comparable (RR, 1.14; 95% CI, 0.89 to 1.45; p = 0.29). Interstage mortality was 13.8% and 4.6% in the MBTS and RV-PAS cohorts, respectively, and was significantly lower for RV-PAS (RR, 2.85; 95% CI, 1.65 to 4.89; p < 0.00002). However, patients with MBTS had fewer shunt interventions (RR, 0.55; 95% CI, 0.44 to 0.68; p < 0.001; I² = 00%).
Our pooled analysis demonstrated no survival benefit for the MBTS or RV-PAS in patients undergoing the Norwood procedure. There appears to be an advantage with the RV-PAS with regard to interstage mortality at the cost of an increased rate of shunt intervention.

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Original articlePediatric cardiacA Comparison of the Modified Blalock-Taussig Shunt With the Right Ventricle-to-Pulmonary Artery Conduit

Background

Methods

Results

Conclusions

Section snippets

Patients and Methods

SP1 Mortality

Comment

J Thorac Cardiovasc Surg

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

J Thorac Cardiovasc Surg

Original article
Pediatric cardiac
A Comparison of the Modified Blalock-Taussig Shunt With the Right Ventricle-to-Pulmonary Artery Conduit