A Single-Centre Retrospective Review ofModified Blalock-Taussig Shunts: A22-YearExperience.

Abstract

This single-centre retrospective study explores demographics and outcomes of patients who underwent a modified Blalock-Taussig shunt (MBTS) over a 22-year period. The predominant surgical approach in this study is a lateral thoracotomy, in contrast to a midline sternotomy. Risks and outcomes of this approach are compared with national and international literature. Demographic, anatomical, clinical, surgical and outcome data of all patients who underwent a MBTS between 2000 and 2022 were collected and analysed, excluding Norwood procedures, which are not performed at this institution. Short- and long-term morbidity and mortality is described. Over the 22-year study period, 185 MBTS were performed in 162 patients, at a median age of 16 days (interquartile range [IQR] 5-59 days) and weight of 3.47 kg (IQR 3-4.25 kg, minimum weight 2 kg). Of these, 79% of patients had a biventricular circulation. Cardiac diagnoses included both univentricular and biventricular anatomy; tetralogy of Fallot (TOF) (36%), transposition of the great arteries/ventricular septal defect/pulmonary stenosis (TGA/VSD/PS) (11%), pulmonary atresia with intact ventricular septum (PA/IVS) (23%), pulmonary atresia with ventricular septal defect (PA/VSD) (14%), other (16%). The most common size of MBTS was 4 mm (71%); 93% were performed via a lateral thoracotomy. There were 47 cases of major operative morbidity, which did not differ significantly with cardiac diagnosis. Overall all-cause mortality was 13.5%. Early operative mortality was 4.3%. Mortality varied with cardiac diagnosis, 6% with TOF and 19% with PA/IVS. There was no era effect on mortality rates, however a lower frequency of major morbidity (23% vs 7%, p=0.03) was observed in the most recent third of the study period. Risk factors for shunt reintervention or mortality included weight <2.5 kg (HR=2.79 [1.37, 5.65], p=0.005), and pre- (HR=3.31 [1.86, 5.9], p<0.001) or postoperative lactic acidosis (HR=1.37 [1.25,1.5], p<0.001). These rates are comparable to those in the literature, with the predominant approach a midline sternotomy. Hobbes etal. from Royal Children's Hospital in Melbourne, Australia reported an overall and operative mortality rate of 12.8% and 5.2%, respectively, while Sasikumar etal. from The Hospital for Sick Children in Toronto, Canada reported an overall and operative mortality of 16% and 10%, respectively, for MBTS procedures over the same time period, however including smaller weight infants. Petrucci etal. described outcomes from the multi-institutional Society of Thoracic Surgeons Congenital Heart Surgery database reporting an overall mortality in MBTS of 7.2% in 1,273 patients with both single and double ventricle anatomy. Mortality rates and risk factors for adverse outcomes are comparable to those previously reported for both univentricular and biventricular groups. These results highlight that outcomes of MBTS performed via lateral thoracotomy are comparable to those by midline sternotomy as reported in the literature. Operating via the lateral approach may be advantageous as it avoids the complications of a midline sternotomy.