Surgical outcomes of the systemic-to-pulmonary artery shunt: risk factors of post-operative acute events and effectiveness of regulation of pulmonary blood flow with metal clips

OBJECTIVES

The aim of this study was to analyze the risk factors for acute events after systemic-to-pulmonary shunt (SPS) and to investigate the effectiveness of pulmonary blood flow regulation with a metal clip.

METHODS

The case histories of 116 patients (78 biventricular [BV] and 38 single ventricle [SV] physiology) who underwent SPS between 2010 and 2021 were retrospectively reviewed. Our strategy was to delay SPS until 1 month of age; pulmonary blood flow (PBF) regulation by partial clipping of the graft, if needed. Cases of aortic cross-clamping were excluded from this study.

RESULTS

CPB was used in 49 (42%) patients: the median age at SPS was 1 month (2 days to 16 years), and the sternotomy approach in 65. Discharge survival was 98.3% (114/116); hospital death occurred in 1.7% due to coronary ischemia. Inter-stage mortality occurred in 1.7% (shunt thrombosis, 1; pneumonia, 1). Pre-discharge acute events occurred in 7 patients (6.0%): thrombosis 3, pulmonary over-circulation 2, and coronary ischemia 2. Multiple logistic regression analysis revealed that pulmonary atresia with intact ventricular septum (PA/IVS) (p = 0.0253) was an independent risk factor for acute events. Partial clipping of the graft was performed in 24 patients (pulmonary atresia 15) and clip removal was performed by catheter intervention in 9 patients; no coronary ischemic events and graft injury occurred in these patients.

CONCLUSION

Surgical outcomes after SPS were acceptable and metal clip regulation of pulmonary blood flow appears to be safe and effective. PA/IVS was still a significant risk factor for acute events.

Exploratory Use of Glycoprotein IIb/IIIa Inhibition in Prevention of Blalock-Taussig Shunt Thrombosis

OBJECTIVES

Morbidity and mortality related to modified Blalock-Taussig shunt (mBTTS) thrombosis remain a significant risk. Platelet inhibition following mBTTS may reduce this risk. However, oral antiplatelet agents have variable absorption following surgery. We determine risk factors for mBTTS thrombosis and hypothesize that IV glycoprotein IIb/IIIa inhibitor (tirofiban) as a bridge to oral aspirin reduces the rate of shunt thrombosis in the immediate postoperative period. End points within the 14-day follow-up period include mBTTS thrombosis, overall thrombosis, bleeding, length of stay, and mortality.

DESIGN

Retrospective, Institutional Review Board-approved cohort study.

SETTING

Single-center cardiac ICU.

PATIENTS

Patients under the age of 18 who had an mBTTS placed within the study period of January 2008 to December 2018 were included.

INTERVENTIONS

Patients were divided into two groups: standard of care (SOC) anticoagulation alone and SOC with tirofiban as a bridge to oral aspirin.

MEASUREMENTS AND MAIN RESULTS

Freedom from mBTTS thrombosis was estimated using the Kaplan-Meier method. A multivariable predictive model using the four most significant risk factors was developed using logistic regression. A total of 272 patients were included: 36 subjects in the SOC/tirofiban group and 236 in the SOC group. Shunt thrombosis occurred in 26 (11%) SOC group with zero in SOC/tirofiban group ( p = 0.03). The median time to thrombosis was 0 days (range, 0-12 d). The area under the curve for the predictive model (anticoagulation group, history of coagulopathy, intraoperative shunt clipping, and shunt size/weight ratio) is 0.790 ( p < 0.001). Prevalence of bleeding and mortality was not significantly different between the groups.

CONCLUSIONS

Highest risk for shunt thrombosis following mBTTS occurs within the first few days after surgical procedure. Tirofiban is a safe addition to SOC and may be an effective strategy to prevent early mBTTS thrombosis.

Clinical implications of acute shunt thrombosis in paediatric patients with systemic-to-pulmonary shunt re-interventions

PURPOSE

Systemic-to-pulmonary shunts are used as a source of pulmonary blood flow in palliated Congenital Heart Disease in neonates and young infants. Shunt thrombosis, often requiring shunt interventions during index hospitalisation, is associated with poor outcomes. We hypothesised that extensive use of perioperative pro-coagulant products may be associated with shunt thrombosis.

METHODS

Children (≤18 years) undergoing systemic-to-pulmonary shunts with in-hospital shunt reinterventions between 2016 and 2020 were reviewed retrospectively. Perioperative associations to shunt thrombosis were examined by univariate logistic regression and Wilcoxon rank sum tests as appropriate. Cox and log transformed linear regression were used to analyse postoperative ventilation duration, length of stay, and cost.

RESULTS

Of 71 patients requiring in-hospital shunt intervention after systemic-to-pulmonary shunts, 10 (14%) had acute shunt thrombosis, and among them five (50%) died. The median age was four (interquartile range: 0-15) months. There were 40 (56%) males, 41 (58%) had single ventricle anatomy, and 29 (40%) were on preoperative anticoagulants. Patients with acute shunt thrombosis received greater volume of platelets (p = 0.04), cryoprecipitate (p = 0.02), and plasma (p = 0.04) postoperatively in the ICU; experienced more complications (p = 0.01) including re-exploration for bleeding (p = 0.008) and death (p = 0.02), had longer hospital length of stays (p = 0.004), greater frequency of other arterial/venous thrombosis (p = 0.02), and greater hospital costs (p = 0.002).

CONCLUSIONS

Patients who develop acute shunt thrombosis receive more blood products perioperatively and experience worse hospital outcomes and higher hospital costs. Future research on prevention/early detection of shunt thrombosis is needed to improve outcomes in infants after systemic-to-pulmonary shunt surgery.

Predictors of death after receiving a modified Blalock-Taussig shunt in cyanotic heart children: A competing risk analysis

Objective

To determine risk factors affecting time-to-death ≤90 and >90 days in children who underwent a modified Blalock-Taussig shunt (MBTS).

Methods

Data from a retrospective cohort study were obtained from children aged 0–3 years who experienced MBTS between 2005 and 2016. Time-to-death (prior to Glenn/repair), time-to-alive up until December 2017 without repair, and time-to-progression to Glenn/repair following MBTS were presented using competing risks survival analysis. Demographic, surgical and anesthesia-related factors were recorded. Time-to-death ≤90 days and >90 days was analyzed using multivariate time-dependent Cox regression models to identify independent predictors and presented by adjusted hazard ratios (HR) and 95% confidence intervals (CI).

Results

Of 380 children, 119 died, 122 survived and 139 progressed to Glenn/repair. Time-to-death probability (95% CI) within 90 days was 0.18 (0.14–0.22). Predictors of time-to-death ≤90 days (n = 63) were low weight (<3 kg) (HR 7.6, 95% CI:2.8–20.4), preoperative ventilator support (HR 2.7, 95% CI:1.3–5.6), postoperative shunt thrombosis (HR 5.0, 95% CI:2.4–10.4), bleeding (HR 4.5, 95% CI:2.1–9.4) and renal failure (HR 4.1, 95% CI:1.5–10.9). Predictors of time-to-death >90 days (n = 56) were children diagnosed with pulmonary atresia with ventricular septal defect and single ventricle (compared to tetralogy of fallot) (HR 3.2, 95% CI:1.2–7.7 and HR 3.1, 95% CI:1.3–7.6, respectively), shunt size/weight ratio >1.1 vs <0.65 (HR 6.8, 95% CI:1.4–32.6) and longer duration of mechanical ventilator (HR 1.002, 95% CI:1.001–1.004). Shunt size/weight ratio ≥1.0 (vs <1.0) and ≥0.65 (vs <0.65) were predictors for overall time-to-death in neonates and toddlers, respectively (HR 13.1, 95% CI:2.8–61.4 and HR 7.8, 95% CI:1.7–34.8, respectively).

Conclusions

Perioperative factors were associated with time-to-death ≤90 days, whereas particular cardiac defect, larger shunt size/weight ratio, and longer mechanical ventilation were associated with time-to-death >90 days after receiving MBTS. Larger shunt size/weight ratio should be reevaluated within 90 days to minimize the risk of shunt over flow.

Central Vascular Thrombosis in Neonates with Congenital Heart Disease Awaiting Cardiac Intervention

Central vascular thrombosis (CVT) in critically ill neonates carries significant clinical implications. Neonates with congenital heart disease (CHD) awaiting cardiac intervention might be associated with increased risk of thrombosis. Outcome analysis was undertaken. An analysis of 77 neonates with CHD who were admitted to the NICU prior to cardiac intervention between January 2015 and December 2016 was undertaken. Patients requiring extracorporeal life support prior to any cardiac intervention, or receiving prophylactic anticoagulation not related to central vascular catheter (CVC) were excluded. Diagnosis of CVT was provided based on clinical indication and verified with imaging that warranted anticoagulation therapy. Location of CVC and extent of CVT along with treatments, outcomes, and vascular access types and durations were assessed. Logistic regression multivariate analysis was used to assess predictors of outcome. Neonates with CHD were complicated with CVT in 10.4%. Longer duration of CVC was also associated with thrombosis in neonates with CHD (72.7 days vs. 29.3 days, p < 0.001). Independent predictors of outcome included lower gestational age and CHD with single-ventricle (SV) anatomy (p < 0.05). In neonates with CHD awaiting cardiac intervention risk of CVT is substantial. Duration CVC, lower gestational age and SV anatomy are risk determinants of outcome. Standardized development of customized surveillance protocols tailored to this unique subsets of neonates and adherence to quality guidelines can influence outcome.

Outcomes of systemic-to-pulmonary artery shunt for single ventricular heart with extracardiac total anomalous pulmonary venous connection

OBJECTIVES

A few studies have described the outcomes of systemic-to-pulmonary artery shunt (SPS) for functional single ventricular heart with extracardiac total anomalous pulmonary venous connection (TAPVC). This study aimed to examine the outcomes of SPS with extracardiac TAPVC and identify the predictors of mortality before bidirectional Glenn operation (BDG).

METHODS

Medical records of 41 children with single ventricular heart and extracardiac TAPVC who underwent SPS between 1998 and 2019 were reviewed retrospectively. The median age and body weight at SPS were 36 days and 3.4 kg, respectively. Surgical outcomes and predictors of mortality were investigated.

RESULTS

Four operative deaths (10%) and 10 late deaths (27%) occurred before BDG. Of all the children, 19 underwent BDG at a median of 10 months since SPS and eight are waiting for BDG. In the multivariate analysis, preoperative pulmonary venous obstruction (p = 0.01) at initial surgery was most predictive of death before BDG. Patients who underwent simultaneous SPS and TAPVC repair were younger, had high preoperative rate of pulmonary venous obstruction, and more deaths before BDG.

CONCLUSIONS

Survival outcomes of SPS for SVH with extracardiac TAPVC were improved as a whole due to the increase in knowledge and technique of management SPS. However, the patients who have preoperative pulmonary venous obstruction (PVO) and need SPS and TAPVC repair concomitantly in the early postnatal period have poor outcomes and still challenging. In such a case, staged TAPVC repair and SPS may be beneficial.

Platelet Inhibition With IV Glycoprotein IIb/IIIa Inhibitor to Prevent Thrombosis in Pediatric Patients Undergoing Aortopulmonary Shunting

OBJECTIVES

Shunt thrombosis, a potential complication of aortopulmonary shunting, is associated with high mortality. Commonly used oral antiplatelet drugs such as aspirin demonstrate variable absorption and inconsistent antiplatelet effect in critically ill patients early after surgery. IV glycoprotein IIb/IIIa inhibitors are antiplatelet agents with rapid and reproducible effect that may be beneficial as a bridge to oral therapy.

DESIGN

Retrospective review of pediatric patients undergoing treatment with IV tirofiban. Discarded blood samples were used to determine pharmacokinetic parameters.

SETTING

Pediatric cardiac ICU at a single institution.

PATIENTS

Fifty-two pediatric patients (< 18 yr) undergoing surgical aortopulmonary shunt procedure who received tirofiban infusion as a bridge to oral aspirin.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Primary outcome measures were shunt thrombosis and bleeding events, whereas secondary outcomes included measurement of platelet inhibition by thromboelastography with platelet mapping and pharmacokinetic analysis (performed in a subset of 15 patients). Shunt thrombosis occurred in two of 52 patients (3.9%) after prophylaxis treatment with tirofiban; both thrombosis events occurred after discontinuation of the drug. One patient (1.9%) experienced bleeding complication during the infusion. A tirofiban bolus of 10 µg/kg and infusion of 0.15 µg/kg/min resulted in significantly increased platelet inhibition via adenosine diphosphate pathway (median 66% [43-96] pre-tirofiban compared with 97% [92-99%] at 2 hr; p < 0.05). Half-life of tirofiban in plasma was 142 ± 1.5 minutes, and the average steady-state concentration was 112 ± 62 ng/mL. Age and serum creatinine were significant covariates associated with systemic clearance. Dosing simulations were generated based upon one compartment model.

CONCLUSIONS

IV glycoprotein IIb/IIIa inhibitor as a bridge to oral antiplatelet therapy is safe in pediatric patients after aortopulmonary shunting. Dosing considerations should include both age and renal function. Randomized trials are warranted to establish efficacy compared with current anticoagulation practices.

Blalock-Taussig Shunt Size: Should it be Based on Body Weight or Target Branch Pulmonary Artery Size?

The study aimed to revisit the in-hospital predictors of shunt thrombosis (ST) in the foreground of the pulmonary artery size in patients who received modified Blalock-Taussig shunt (mBTS) as the first-stage palliation. Data from 80 patients who received mBTS as their initial palliative procedure between February 2012 and January 2017 was retrospectively collected. The median age and weight of the patients at the time of their mBTS procedure was 4 days (IQR 2-22 days) and 3.2 kg (IQR 2.8-3.7 kg), respectively. Of the 80 patients in the study, 11 (13.8%) developed ST. The diameter and corresponding z scores of the pulmonary arteries were significantly lower in patients with ST. The median shunt size/shunted pulmonary artery size (S/PA) ratio was considerably higher in patients with ST. In logistic regression analysis, pulmonary artery hypoplasia (PAH) [odds ratio (OR) = 13.7 (0.06-0.21), p < 0.001], S/PA ratio ≥ 0.9 [OR = 8.1 (0.03-0.53), p = 0.03], prematurity [OR = 9.5 (0.05-0.33), p = 0.003], and shunt size/weight (S/W) ratio ≥ 1.3 [OR = 6.4 (0.04-0.67), p = 0.012] were found to have a significant impact on ST. The best combination of sensitivity and specificity of the S/W (0.73 and 0.75) and the S/PA ratio (0.73 and 0.80) were achieved at the cut-off value of 1.3 and 0.9, respectively. The Youden index of S/PA was 0.52. While the area under the curve (AUC) of the S/W ratio was 0.686 ± 0.12 (p = 0.049), the AUC of the S/PA ratio was 0.791 ± 0.08 (p = 0.002). In conclusion, instead of weight, considering the size of the target pulmonary artery and thereby, the S/PA ratio would be more instructive in determining shunt size. There were a high number of patients in our study who showed PAH having received a shunt size based on their body weight. By contrast, our results showed that the S/PA ratio of ≥ 0.9 would be a good predictor of in-hospital ST.