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Objectives: Our goal was to conduct a hemodynamic analysis of a novel animal model of Fontan physiology. Poor late-term outcomes in Fontan patients are believed to arise from Fontan-induced hemodynamics, but the mechanisms remain poorly understood. Recent advances in surgical experimentation have resulted in the development of a chronic sheep model of Fontan physiology; however, detailed analysis of this model is lacking. Methods: We created a single-stage Fontan model in juvenile sheep with normal biventricular circulation. The superior vena cava was anastomosed to the main pulmonary artery, and the inferior vena cava was connected to the main pulmonary artery using an expanded polytetrafluoroethylene conduit. Longitudinal hemodynamics, including catheterization and magnetic resonance imaging were evaluated. Results: Four out of 12 animals survived, with the longest surviving animal living 3 years after single-stage Fontan. We showed a significant era effect regarding survival (1 out of 8 and subsequently 3 out of 4 animals surviving beyond 2 months) attributed in large part to the procedural learning curve. Key characteristics of Fontan hemodynamics, namely systemic venous hypertension and low normal cardiac output, were observed. However, recapitulation of passive human Fontan hemodynamics is affected by volume loading of the right ventricle given an anatomic difference in sheep azygous venous anatomy draining to the coronary sinus. Conclusions: A significant learning curve exists to ensure long-term survival and future surgical modifications, including banding of the main pulmonary artery and ligation of the azygous to coronary sinus connection are promising strategies to improve the fidelity of model hemodynamics.

Background: Single-ventricle cardiac defects (SVCDs) are among of the most health care resource–intensive congenital diseases. Although SVCDs are traditionally palliated using the Norwood pathway, in the last 2 decades select programs have used the hybrid strategy, which redistributes the operative and interstage risks. This study sought to characterize resource use for a cohort of patients with hybrid-palliated SVCD. Methods: All patients with SVCDs who underwent palliation with the hybrid strategy and who were followed up exclusively at our institution from January 2008 to December 2021 were included. End points were death, Norwood conversion, orthotopic heart transplantation, 6 months post-Fontan status, or 4 years of age in those patients who had not completed staged palliation. Primary end points included total days hospitalized, number of cardiology visits, echocardiograms, catheterizations, and advanced imaging performed. Results: Of 135 patients with a diagnosis of SVCD, 72 survived for 6 months after the Fontan procedure. By patient-year for the entirety of the pathway, patients had a median hospital length of stay of 16 days (interquartile range [IQR], 12-25 days), 7 cardiology visits (IQR, 6-9), 8 echocardiograms (IQR, 7-10), and 0.7 catheterizations (IQR, 0.4-1.1). The interstage 1 period had the heaviest resource burden requiring intense cardiology follow-up and echocardiography surveillance. Cardiac catheterizations and advanced imaging were most prevalent during interstage 2 period, with a median of 2 (IQR, 1-2) catheterizations and 36 (40%) patients undergoing advanced imaging. The total median number of hospital days per patient was 63 days (IQR, 47-98.5 days). Conclusions: Resource use for the care of patients with SVCDs is significant. The intensity of surveillance decreases as patients progress through the pathway. In comparison with published Norwood pathway data, resource intensity and use patterns in hybrid palliation are comparable.

Objectives: Palliative treatment of cyanotic congenital heart disease (CCHD) uses systemic-to-pulmonary conduits, often a modified Blalock–Taussig–Thomas shunt (mBTTs). Expanded polytetrafluoroethylene (ePTFE) mBTTs have associated risks for thrombosis and infection. The Human Acellular Vessel (HAV) (Humacyte, Inc) is a decellularized tissue-engineered blood vessel currently in clinical trials in adults for vascular trauma, peripheral artery disease, and end-stage renal disease requiring hemodialysis. In addition to restoring blood flow, the engineered HAV demonstrates the capacity for host cellular remodeling into native-like vasculature. Here we report preclinical evaluation of a small-diameter (3.5 mm) HAV as a mBTTs in a non-human primate model. Methods: We implanted 3.5 mm HAVs as right subclavian artery to pulmonary artery mBTTs in non-immunosuppressed juvenile rhesus macaques (n = 5). HAV patency, structure, and blood flow were assessed by postoperative imaging from 1 week to 6 months. Histology of HAVs and surrounding tissues was performed. Results: Surgical procedures were well tolerated, with satisfactory anastomoses, showing feasibility of using the 3.5 mm HAV as a mBTTs. All macaques had some immunological reactivity to the human extracellular matrix, as expected in this xenogeneic model. HAV mBTTs remained patent for up to 6 months in animals, exhibiting mild immunoreactivity. Two macaques displaying more severe immunoreactivity to the human HAV material developed midgraft dilatation without bleeding or rupture. HAV repopulation by host cells expressing smooth muscle and endothelial markers was observed in all animals. Conclusions: These findings may support use of 3.5 mm HAVs as mBTTs in CCHD and potentially other pediatric vascular indications.

Objective: The prevalence of postoperative cardiac arrest (CA) increases with cardiothoracic surgical case complexity and is associated with a 40% to 50% mortality. Despite having a low overall surgical mortality rate at our center, our postoperative CA rates were higher than expected, with an observed-to-expected ratio of 2.6. Utilizing quality improvement methodology, we evaluated the influence of proactive risk mitigation on postprocedure CA in a high-risk cohort of pediatric cardiac patients. Methods: This single-center study utilized the Institute for Healthcare Improvement model. We created and implemented our Proactive Mitigation to Decrease Serious Adverse Events program in July 2020, prospectively enrolling preidentified high-risk patients. Enrolled patients underwent scheduled multidisciplinary reviews via virtual platform at 2 periprocedural time points with discussion of patient-specific risks and the subsequent development of proactive risk mitigation plans. Primary outcome measures were derived from the Pediatric Cardiac Critical Care Consortium national registry and included rate of postprocedure CA within 7 days and an institution-specific observed-to-expected ratio for postoperative CA. Results: Our baseline median number of high-risk cases between postprocedure CAs was 3. Following project initiation, median high-risk cases between events increased to 7. Our observed-to-expected ratio for postoperative CA decreased from 2.56 during the 12 months before Proactive Mitigation to Decrease Serious Adverse Events program implementation to 1.01 during the 12 months after Proactive Mitigation to Decrease Serious Adverse Events program implementation, and hospital length of stay decreased by ∼10 days. Conclusions: Implementation of periprocedure-related proactive risk mitigation strategies in high-risk pediatric cardiac patients led to improvement in postprocedure CA with a 133% increase in high-risk cases between events.

Objective: Pulmonary artery reconstruction during comprehensive stage 2 (CS2) procedure can be challenging. Since 2017, we have employed preemptive left pulmonary artery (LPA) stenting. We hypothesized that LPA stenting promotes adequate growth and without compromising Fontan candidacy. Herewith, we report our midterm results. Methods: From 2002 to 2020, 159 patients underwent CS2. Patients were divided as follows: no stent (n = 122; Group 1) and perioperative LPA stent (n = 37; Group 2). Group 2 was subdivided according to unplanned stent (n = 17; Group 2a) or preemptive stent (n = 20; Group 2b). Relevant perioperative data was reviewed. Nonparametric statistics were utilized. Results: Median age and weight at surgery and hospital length of stay after CS2 did not differ between groups. Median cardiopulmonary bypass and crossclamp times were significantly greater in Group 1 (265 vs 243 minutes [P = .021] and 46 vs 26 minutes [P = .008]). In-hospital mortality was similar between Groups 1 and 2 (9.0% vs 18.9%, respectively [P = .1348]). Group 2b demonstrated a superior survival compared to Group 2a (P = .0335) but not Group 1 (P > .9999). Preemptive stenting significantly increased median hilar LPA diameter at CS2 exit angiogram compared with no stenting (P