Cardiopulmonary Bypass Reduces Early Thrombosis of Systemic-to-Pulmonary Artery Shunts

Outcome after stage 1 palliation in non-hypoplastic left heart syndrome patients as a univentricular palliation

OBJECTIVES

Studies focused on infants with univentricular heart undergoing stage I palliation other than the Norwood procedure remain a topic of great interest. This study evaluated the outcome of infants who underwent systemic to pulmonary shunt (SPS) or pulmonary artery banding (PAB).

METHODS

Infants who underwent SPS or PAB as stage I palliation between 1994 and 2019 were included. Survival and late systemic ventricular function were evaluated.

RESULTS

Out of 242 patients, 188 underwent SPS (77.7%) and 54 PAB (22.3%). Main diagnosis included tricuspid atresia, unbalanced atrioventricular septal defects, double inlet left ventricles and single ventricles with other morphology. Thirty-eight patients died before stage II palliation (15.7%). Stage II palliation was performed in 182 patients (75.2%), and mortality between stages II and III was 11 (5.6%). Stage III palliation was performed in 160 (66.1%) patients. Survival at 1, 5 and 15 years after stage I procedure was 81.9, 77.1 and 76.2%, respectively, and similar between both procedures (P = 0.97). Premature birth [P = 0.03, hazard ratio (HR) = 2.1], heterotaxy (P = 0.006, HR = 2.4) and dominant right ventricle (P = 0.015, HR = 2.2) were factors associated to mortality. Unbalanced atrioventricular septal defect (P = 0.005, HR = 4.6) was a factor associated to systemic ventricular dysfunction.

CONCLUSIONS

In patients with univentricular heart who underwent SPS and PAB as stage I palliation, survival at 15 years was 76%, regardless of th chosen approach. Premature birth, heterotaxy and dominant right ventricle were associated to mortality.

Impact of total anomalous pulmonary venous connection in staged single ventricle palliation

BACKGROUND

Total anomalous pulmonary venous connection (TAPVC) with a functional single ventricle is a risk factor for mortality during staged palliation. This study aimed to assess TAPVC's impact on staged palliation outcomes.

METHODS

In a total of 602 patients with a functional single ventricle who underwent stage 1 palliation (S1P) at our center between 2001 and 2020, 39 (6.5%) patients were associated with TAPVC. Median age at S1P was 12.0 (interquartile range, 7-21) days with a body weight of 3.1 (interquartile range, 2.8-3.6) kg. Outcomes during staged palliation were compared with the remaining 563 patients without TAPVC. Risk factors for mortality were identified using a Cox proportional hazards regression model.

RESULTS

Primary diagnosis in functional single-ventricle patients with TAPVC included hypoplastic left heart syndromes (n = 13), unbalanced atrioventricular septal defects (n = 12) tricuspid atresias (n = 2), double inlet left ventricle (n = 1), and others (n = 11). Types of TAPVC were supracardiac (n = 21), cardiac (n = 10), infracardiac (n = 6), and mixed (n = 2). Pulmonary venous obstruction (PVO) was associated in 19 (49%) patients. S1Ps included Norwood (n = 13), aortopulmonary shunt (n = 21), and pulmonary artery banding (n = 5). Thirty-day mortality after S1P was significantly increased in patients with TAPVC vs without TAPVC (43.6% vs 16.3%; P < .001). After bidirectional cavopulmonary shunt and total cavopulmonary connection procedures, mortality was low in both groups, and no statistically significant differences were found. Correction of TAPVC at the time of S1P was not found to be a significant risk factor in univariable Cox regression analysis. In univariate and multivariate analysis, PVO was identified as an independent risk factor for mortality in patients with TAPVC (P < .001).

CONCLUSIONS

Overall survival is lower in TAPVC single-ventricle patients than in non-TAPVC patients. Most deaths after S1P were associated with TAPVC, but not after S2P. PVO is a mortality risk factor in TAPVC patients.

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.

In-hospital Morbidity and Mortality Following Modified Blalock-Taussig-Thomas Shunts

BACKGROUND

The modified Blalock-Taussig-Thomas shunt (mBTTs) is a critically important palliation for patients with insufficient pulmonary blood flow associated with congenital heart disease. Following creation of a mBTTs, patients experience high rates of early postoperative morbidity and mortality.

METHODS

This is a single-institution retrospective cohort study. A query of the Society of Thoracic Surgeons database identified relevant patients whose health records were manually queried for echocardiography and operative reports. Patients with ductal-dependent systemic circulation were excluded. Primary outcomes were early serious adverse events and in-hospital mortality. Secondary outcomes were time to primary outcomes and postoperative lengths of stay. We investigated the correlation of demographics, presence of competitive pulmonary blood flow, and surgical and anatomic factors on outcomes.

RESULTS

After exclusions, our cohort resulted in 155 patients. 33 (21.3%) patients experienced an early serious adverse event, ten (6.5%) early shunt malfunction, and 11 (7.1%) in-hospital mortality. Smaller shunt size, smaller shunted pulmonary artery size, surgical approach, and site of proximal shunt anastomosis were independently associated with morbidity and mortality.

CONCLUSIONS

Anatomical elements imparting increased resistance along the mBTTs predispose to increased morbidity and mortality, particularly in the early postoperative period. Despite the significant heterogeneity of patients receiving such shunts, similar risk profiles are observed regardless of lesion or presence of competitive flow. Surgical approach via thoracotomy with shunt anastomosis to the subclavian artery, where feasible, results in the subclavian artery as the point of natural resistance allowing for placement of larger shunts, yielding lower morbidity and mortality.

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.