Surgical pulmonary arterioplasty at bidirectional cavopulmonary anastomosis leads to favorable pulmonary hemodynamics at final stage palliation.

Objective: Pulmonary arterioplasty (PA plasty) at bidirectional cavopulmonary anastomosis (BDCA) is associated with increased morbidity, but outcomes to final stage palliation are unknown. We sought to determine the influence of PA plasty on pulmonary artery growth and hemodyamics at Fontan. Methods: We retrospectively reviewed clinical data and outcomes for BDCA patients from 2006 to 2018. PA plasty was categorized by extent (type 1-4), as previously described. Outcomes included pulmonary artery reintervention and mortality before final palliation. Results: Five hundred eighty-eight patients underwent BDCA. One hundred seventy-nine patients (30.0%) underwent concomitant PA plasty. Five hundred seventy (97%) patients (169 [94%] PA plasty) survived to BDCA discharge. One hundred forty out of 570 survivors (25%) required PA/Glenn reintervention before final stage palliation (59 out of 169 [35%]) PA plasty; 81 out of 401 (20%) non-PA plasty; P < .001). Twelve-, 24-, and 36-month freedom from reintervention after BDCA was 80% (95% CI, 74-86%), 75% (95% CI, 69-82%), and 64% (95% CI, 57-73%) for PA plasty, and 95% (95% CI, 93-97%), 91% (95% CI, 88-94%), and 81% (95% CI, 76-85%) for non-PA plasty (P < .001). Prefinal stage mortality was 37 (6.3%) (14 out of 169 PA plasty; 23 out of 401 non-PA plasty; P = .4). Five hundred four (144 PA plasty and 360 non-PA plasty) patients reached final stage palliation (471 Fontan, 26 1.5-ventricle, and 7 2-ventricular repair). Pre-Fontan PA pressure and pulmonary vascular resistance were 10 mm Hg (range, 9-12 mm Hg) and 1.6 mm Hg (range, 1.3-1.9 mm Hg) in PA plasty and 10 mm Hg (range, 8-12 mm Hg) and 1.5 mm Hg (range, 1.3-1.9 mm Hg) in non-PA plasty patients, respectively (P = .29, .6). Fontan hospital mortality, length of stay, and morbidity were similar. Conclusions: PA plasty at BDCA does not confer additional mortality risk leading to final palliation. Despite increased pulmonary artery reintervention, there was reliable pulmonary artery growth and favorable pulmonary hemodynamics at final stage palliation.

Angiographic tool to detect pulmonary arteriovenous malformations in single ventricle physiology.

OBJECTIVE: Individuals with single ventricle physiology who are palliated with superior cavopulmonary anastomosis (Glenn surgery) may develop pulmonary arteriovenous malformations. The traditional tools for pulmonary arteriovenous malformation diagnosis are often of limited diagnostic utility in this patient population. We sought to measure the pulmonary capillary transit time to determine its value as a tool to identify pulmonary arteriovenous malformations in patients with single ventricle physiology. METHODS: We defined the angiographic pulmonary capillary transit time as the number of cardiac cycles required for transit of contrast from the distal pulmonary arteries to the pulmonary veins. Patients were retrospectively recruited from a single quaternary North American paediatric centre, and angiographic and clinical data were reviewed. Pulmonary capillary transit time was calculated in 20 control patients and compared to 20 single ventricle patients at the pre-Glenn, Glenn, and Fontan surgical stages (which were compared with a linear-mixed model). Correlation (Pearson) between pulmonary capillary transit time and haemodynamic and injection parameters was assessed using angiograms from 84 Glenn patients. Five independent observers calculated pulmonary capillary transit time to measure reproducibility (intraclass correlation coefficient). RESULTS: Mean pulmonary capillary transit time was 3.3 cardiac cycles in the control population, and 3.5, 2.4, and 3.5 in the pre-Glenn, Glenn, and Fontan stages, respectively. Pulmonary capillary transit time in the Glenn population did not correlate with injection conditions. Intraclass correlation coefficient was 0.87. CONCLUSIONS: Pulmonary angiography can be used to calculate the pulmonary capillary transit time, which is reproducible between observers. Pulmonary capillary transit time accelerates in the Glenn stage, correlating with absence of direct hepatopulmonary venous flow.

Glenn shunt as a rescue strategy for acute right ventricular failure after right ventricular myocardial infarction.

We present the case of a 52-year-old woman with cardiogenic shock and refractory right ventricular failure due to spontaneous dissection of the right coronary artery. She remained dependent on mechanical support for several weeks. Both a right ventricular assist device implant and a bidirectional cavopulmonary anastomosis were explored as long-term support options. A history of malignancy and possible right ventricular functional recovery resulted in a decision in favour of the bidirectional cavopulmonary anastomosis and concomitant tricuspid valve annuloplasty. Postoperatively her clinical condition improved significantly, and she could be discharged home. Echocardiography showed normalization of right ventricular dimensions and slight improvement of right ventricular function.

Superior cavopulmonary shunt via right vertical axillary mini-thoracotomy.

We present 2 cases of patients with univentricular heart physiology of different anatomic variants who successfully underwent minimally invasive bidirectional cavopulmonary anastomosis via the right vertical axillary mini-thoracotomy.

Angiographic Tool to Detect Pulmonary Arteriovenous Malformations in Single Ventricle Physiology.

Background: Individuals with single ventricle physiology who are palliated with superior cavopulmonary anastomosis (Glenn surgery) may develop pulmonary arteriovenous malformations (PAVMs). The traditional tools for PAVM diagnosis are often of limited diagnostic utility in this patient population. We sought to measure the pulmonary capillary transit time (PCTT) to determine its value as a tool to identify PAVMs in patients with single ventricle physiology. Methods: We defined the angiographic PCTT as the number of cardiac cycles required for transit of contrast from the distal pulmonary arteries to the pulmonary veins. Patients were retrospectively recruited from a single quaternary North American pediatric center, and angiographic and clinical data was reviewed. PCTT was calculated in 20 control patients and compared to 20 single ventricle patients at the pre-Glenn, Glenn, and Fontan surgical stages (which were compared with a linear-mixed model). Correlation (Pearson) between PCTT and hemodynamic and injection parameters was assessed using 84 Glenn angiograms. Five independent observers calculated PCTT to measure reproducibility (intra-class correlation coefficient). Results: Mean PCTT was 3.3 cardiac cycles in the control population, and 3.5, 2.4, and 3.5 in the pre-Glenn, Glenn, and Fontan stages, respectively. PCTT in the Glenn population did not correlate with injection conditions. Intraclass correlation coefficient was 0.87. Conclusions: Pulmonary angiography can be used to calculate the pulmonary capillary transit time, which is reproducible between observers. PCTT accelerates in the Glenn stage, correlating with absence of direct hepatopulmonary venous flow.

Extremely Long-Term Follow-Up of Dr William Glenn's Original Patient Cohort With Superior Cavopulmonary Anastomosis (1958-1990).

BACKGROUND: Historically, Dr William Glenn performed the first classic superior cavopulmonary anastomosis in a seven-year-old child at Yale in 1958. By 1990, this operation was performed consecutively in over 90 patients. With over 60 years of follow-up, this is the longest survival record of early Glenn patients from the first 30 years. METHODS: We performed a single center, retrospective evaluation of patients undergoing a Glenn operation. A collected list of surviving patients, previously updated in 1988, included demographics, age at procedure, and underlying diagnosis. Follow-up data were obtained in May 2022 using electronic medical records to determine survival, age of survivors, and age of deceased. RESULTS: Ninety-five patients underwent the Glenn operation from 1958 to 1990: 58.9% (n = 56) were male and 41.1% (n = 39) female. Fifteen patients were lost to follow-up, but 12 were alive in 1988. Sixty patients were deceased (68.1%), with an average age of 33.5 ± 18.3(range, 2-78, excluding seven early deaths) years. The oldest patient who passed away was a 78-year-old male with tetralogy of Fallot. Twenty patients remain alive, with an average age of 47.5 (range, 32-66) years. Four patients who are still alive today (20% survivors) are older than 60 years. CONCLUSIONS: Since Dr Glenn's original operation, the technique, timing, and indications have been modified (ie, bidirectional Glenn) to adapt to the current era. By following this initial group of patients, we can approach completion of the survival rates for adult congenital patients who were some of the first pediatric patients to receive this ground-breaking palliative procedure.

Intraoperative transit-time flow measurement of caval veins before and after bidirectional cavopulmonary anastomosis.

BACKGROUND: Haemodynamic changes in caval venous flow distribution occurring during bidirectional cavopulmonary anastomosis operation are still largely unknown. METHODS: Transit time flow measurements were performed in 15 cavopulmonary anastomosis operations. Superior and inferior caval vein flows were measured before and after the cavopulmonary anastomosis. Ratio of superior caval vein to overall caval veins flow was calculated. RESULTS: Mean superior caval vein flow ratio before cavopulmonary anastomosis was higher than previously reported for healthy children. Superior caval vein flow ratio decreased in 14/15 patients after cavopulmonary anastomosis: mean 0.63 ± 0.12 before versus 0.43 ± 0.14 after. No linear correlation between intraoperative superior caval vein pressure and superior caval vein flow after cavopulmonary anastomosis was found. Neither Nakata index nor pulmonary vascular resistance measured at preoperative cardiac catheterisation correlated with intraoperative flows. None of patients died or required a take down. CONCLUSIONS: The higher mean superior caval vein flow ratio before cavopulmonary anastomosis compared to healthy children suggests flow redistribution in univentricular physiology to protect brain and neurodevelopment. The decrease of superior caval vein flow ratio after cavopulmonary anastomosis may reflect the flow redistribution related to trans-pulmonary gradient. The lack of correlation between superior caval vein pressure and superior caval vein flow could be explained by limited sample size and multifactorial determinants of caval veins flow, although pressure remain essential. Larger sample of measurements are needed to find flow range potentially predictive for clinical failure. To authors' knowledge, this is the first intraoperative flow measurement of both caval veins during cavopulmonary operations.

Double outlet left atrium: successful management of a rare entity.

Double-outlet left atrium is an extremely rare congenital ventriculo-atrial mal-alignment anomaly, wherein, the left atrium drains into both ventricles, through either a common atrioventricular valve or two separate atrioventricular valves. The only egress from the right atrium is through an inter-atrial communication. We present a 16-month-old male, diagnosed to have double outlet left atrium and describe its surgical management.

Contemporary risk factors for a longer hospital stay following bidirectional cavopulmonary anastomosis.

BACKGROUND: Despite high survival after bidirectional cavopulmonary anastomosis, a considerable number of patients suffer significant post-operative morbidities related to prolonged length of stay. METHODS: A single-center retrospective cohort study of all consecutive patients undergoing a first-time bidirectional cavopulmonary anastomosis from 2006 to 2019. RESULTS: Prolonged length of stay was defined as hospital stay greater than the 75th percentile for our cohort. Of 195 patients who met inclusion criteria, the median post-operative length of stay was 8 days (interquartile range, 4-15 days). Prolonged length of stay was defined as greater than 15 days. In multivariate analysis, greater than mild systemic atrioventricular valve regurgitation (odds ratio 3.7, 95% CI 1.05-13.068, p = 0.04), longer length of stay after the initial palliative procedure (odds ratio 1.028, 95% CI 1.004-1.05, p = 0.02), and pre-operative higher superior vena cava oxygen saturation (odds ratio 0.922, 95% CI 0.85-0.99, p = 0.04) maintained statistical significance as independent risk and protective factors for prolonged length of stay. A one-level increase in the severity of pre-operative systemic atrioventricular valve regurgitation was associated with a multiplicative change in the odds ratio of prolonged length of stay of 5.45 (p = 0.005) independent of the severity of systemic ventricular dysfunction. CONCLUSION: Pre-operative characteristics with greater than mild systemic atrioventricular valve regurgitation, longer length of stay after the initial palliative procedure, and lower superior vena cava oxygen saturation were associated with prolonged length of stay after a first-time bidirectional cavopulmonary anastomosis.

Left pulmonary artery reconstruction using cryopreserved pulmonary homograft.

In patients with univentricular heart, the Fontan procedure is the final palliation. This is usually staged. A systemic-to-pulmonary artery shunt is performed in the presence of episodes of cyanotic spells in the neonatal period or in some patients in infancy; a bidirectional superior cardiopulmonary anastomosis is preferred early in life. This is followed by the final Fontan palliation on an elective basis later. For an effective bidirectional superior cavopulmonary anastomosis and Fontan palliation, good-sized confluent pulmonary arteries (PAs) are mandatory in addition to favorable hemodynamic data. Patients with discontinuous PAs that are small in size present a surgical challenge at initial palliation as the one described in this report.

High-Risk Anatomic Subsets in Hypoplastic Left Heart Syndrome.

Despite overall improvements in outcomes for patients with hypoplastic left heart syndrome, there remain anatomic features that can place these patients at higher risk throughout their treatment course. These include severe preoperative obstruction to pulmonary venous return, restrictive atrial septum, coronary fistulae, severe tricuspid regurgitation, smaller ascending aorta diameter (especially if <2 mm), and poor ventricular function. The risk of traditional staged palliation has led to the development of alternative strategies for such patients. To further improve the outcomes, we must continue to diligently examine and study anatomic details in HLHS patients.

Analysis of inflammatory cytokines in the chest tube drainage of post-operative superior cavopulmonary connection patients.

INTRODUCTION: Prolonged pleural effusions are common post Fontan operation and are associated with morbidity. Fontan pleural effusions have elevated proinflammatory cytokines. Little is known about the chest tube drainage after a superior cavopulmonary connection. We examined the chest tube drainage and the inflammatory profiles in post-operative superior cavopulmonary connection patients. METHODS: This prospective cohort study enrolled 25 patients undergoing superior cavopulmonary connection and 10 age-similar controls. Data are also compared to 25 previously published Fontan patients and their 15 age-similar controls. Chest tube samples were analysed with a 17-cytokine BioPlex Assay. Descriptive statistics and univariate comparisons were made between groups. RESULTS: Duration of chest tube drainage was significantly shorter in superior cavopulmonary connection patients (median 4 days, [interquartile range 3-5 days]) versus Fontan patients (10 days, [7-11 days], p < 0.0001). Cytokine concentrations were higher on post-operative day 1 in superior cavopulmonary connection patients versus Fontan patients (all p ≤ 0.01), however levels were comparable to age-similar controls. While proinflammatory IL 8, MIP-1ß, and TNF-α concentrations increased in chest tube drainage of Fontan patients from post-operative day 1 to last chest tube day (all p < 0.0001), there was no change in these biomarkers in superior cavopulmonary connection patients, their controls, or Fontan controls. CONCLUSIONS: Our study demonstrates that after superior cavopulmonary connection, proinflammatory cytokines in the chest tube drainage remain similar to biventricular controls of both age groups, unlike the significant rise over time observed in Fontan patients. Inflammation within the chest tube drainage is likely not innate to single ventricle patients.

Early outcomes of fenestrated intra-extracardiac Fontan procedure: Insights, experiences, and expectations.

BACKGROUND: Intraextracardiac Fontan procedure (FP) aimed to combine the advantages of lateral tunnel and extracardiac conduit modifications of the original technique. Herein, we present our early outcomes in patients with intraextracardiac fenestrated FP. METHODS: A retrospective analysis was performed to evaluate intraextracardiac fenestrated Fontan patients between 2014 and 2021. Seventeen patients were operated on with a mean age and body weight of 9.1 ± 5.5 years and 28.6 ± 14.6 kg. RESULTS: Sixteen patients (94%) were palliated as univentricular physiology with hypoplasia of one of the ventricles. One patient (6%) with well-developed two ventricles with double outlet right ventricle and complete atrioventricular septal defect had straddling of the chordae prohibiting a biventricular repair. All of the patients had cavopulmonary anastomosis before Fontan completion, except one case. Fenestration was performed in all cases. Postoperative mean pulmonary artery pressures and arterial oxygen saturation levels at follow-up were 10 ± 2.4 mmHg and 91.3 ± 2.7%, respectively. Mean duration of pleural drainage was 5.4 ± 2.3 days. All of the fenestrations are patent at a mean follow-up period of 4.8 ± 7.7 years, except one case. Any morbidity and mortality were not encountered. CONCLUSIONS: Early outcomes of intraextracardiac fenestrated FP are encouraging. This procedure may improve the results in a patient population who should be palliated as univentricular physiology, especially in cases with complex cardiac anatomy.

Risk factors for death or mechanical ventilation time after bidirectional cavopulmonary anastomosis in a developing country.

BACKGROUND: Glenn procedure is performed for patients with cyanotic CHD and univentricular physiology and has a survival rate above 90%. AIM: To evaluate the risk factors associated with a poor outcome after Glenn procedure. METHODS: The data for this retrospective analysis were collected from a regional Brazilian registry of congenital heart surgeries (ASSIST initiative) from 2014 to 2019. Data from 97 patients who underwent the Glenn procedure were considered. The primary outcomes were prolonged mechanical ventilation (>24 hours post-operatively) or in-hospital death, alone and combined. RESULTS: The overall in-hospital mortality was 13.4% (n = 13). Prolonged mechanical ventilation occurred in 52% (n = 51) of the patients. Our analysis found that risk factors for death or prolonged post-operative mechanical ventilation were cardiopulmonary bypass duration and post-operative lactate, whereas weight-for-age z-score and age at surgery were risk factors for prolonged mechanical ventilation. Cardiopulmonary bypass duration increased (adjusted odds ratio: 1.02; 95 % CI: 1.01, 1.03) and age at surgery decreased (adjusted odds ratio: 0.96; 95 % CI: 0.93, 0.99) the odds of the combined outcome. CONCLUSIONS: Age at surgery, post-operative lactate, and low-weight-for-age z-score are associated with prolonged mechanical ventilation and death following the Glenn procedure.

Systemic Venous Reconstructions During Pediatric Heart Transplantation.

BACKGROUND: Congenital heart disease continues to be an important indication for pediatric heart transplantation (HT) and is often complicated by systemic venous anomalies. The need for reconstruction, surgical technique used, as well as the outcomes of these have limited documentation. METHODS: Descriptive, retrospective study of patients transplanted at Emory University between 2006 and 2017. We reviewed surgical data, follow-up, and interventions for patients necessitating venous reconstruction during transplantation. RESULTS: A total of 179 transplants were performed during the time period of which 74 (41%) required systemic venous reconstruction. Mean age at transplant was 6.3 (±6.16) years, and 74.3% of these patients carried a diagnosis of single ventricle; 51 (68.9%) of 74 patients required pulmonary artery reconstruction at the time of HT. Forty patients required superior vena caval reconstruction, while 22 patients required inferior vena caval reconstruction due to prior palliation or anomaly. Venous anomalies along with other anatomic features necessitated biatrial transplantation in four patients. Posttransplant evaluation revealed systemic venous stenosis in 14 (18.9%) of 74 patients. Eight (10.8%) patients required 12 interventions for the systemic veins. Patients with bilateral Glenn anastomosis prior to transplant were at high risk for the development of stenosis and needing interventions. Systemic venous complications were uncommon in those with native systemic veins without Glenn or Fontan procedure. CONCLUSION: Systemic venous reconstruction needs are high in pediatric HT. Posttransplant stenosis and the need for interventions are relatively common. Current techniques for systemic venous reconstruction for complex congenital heart disease patients may deserve further review to optimize these outcomes.

Coronary Sinus Ostial Obstruction in Single-Ventricle Congenital Heart Disease: Two Patients With Different Outcomes.

Coronary sinus ostial obstruction is an exceedingly rare anomaly that is particularly important to diagnose in patients with single-ventricle heart disease before surgical palliation. We present 2 cases, an infant and an adult, diagnosed with coronary sinus ostial obstruction, with different clinical outcomes due to timing of diagnosis. (Level of Difficulty: Intermediate.).

The Glenn procedure: Clinical outcomes in patients with congenital heart disease in pakistan.

Objectives: Congenital heart defects (CHDs) affect more than 40,000 children annually in Pakistan. Approximately 80' of patients require at least one surgical intervention to achieve a complete or palliative cardiac repair. The Glenn shunt, a palliative procedure is established between superior vena cava (SVC) and the right pulmonary artery to provide an anastomosis offering minimal risk to patients with univentricular heart disease. The aim of this study was to assess the clinical outcomes of the Glenn shunt procedure in patients with complex congenital heart diseases in a developing country like Pakistan. Materials and Methods: A retrospective chart review was conducted on patients who underwent a bidirectional Glenn shunt procedure from July 2006 to June 2017. Data were collected on a structured questionnaire and analyses performed on SPSS version 22. Frequencies and percentages were computed for categorical variables while mean and standard deviation for continuous variables where appropriate. Results: A total of 79 patients underwent the Glenn shunt procedures. The median age was 1.9 years and 54.5' were male. Tricuspid atresia was the primary diagnosis in 30.4' of the patients. Common morbidities included arrhythmias (6.3'), pleural effusion (8.9'), wound infection (3.8'), pneumonia (2.5'), and seizures (3.8'); reopening was required in 2.5' of the patients and 8.8' were readmitted within 30 days of index operation. There were three (3.8') deaths in total. Conclusions: Bidirectional Glenn shunt procedure can be performed safely in patients with ideal characteristics as the first stage palliation and has favorable results with acceptable rate of complications.

Glenn surgery: a safe procedure in the path of univentricular correction / Cirugía de Glenn: un procedimiento seguro en el camino de la corrección univentricular

Abstract Background: This study describes 35 years of experience in a tertiary care level hospital that treats cardiac patients with univentricular heart physiology who underwent Glenn surgery. Methods: The study consisted of a retrospective analysis of patients who underwent Glenn surgery, including variables related to pre-operative, intra-operative, and post-operative morbidity and mortality. Results: From 1980 to 2015, 204 Glenn surgeries were performed. The most common heart disease was tricuspid atresia IB (19.2%). In 48.1% of the cases, the procedure was performed with antegrade flow. A bilateral Glenn procedure was performed in 12.5% of the cases and 10.3% were carried out without using a cardiopulmonary bypass pump. Reported complications included infections, bleeding, arrhythmias, chylothorax, neurological alterations, and pleural effusion. The mortality rate was 2.9% Conclusions: Glenn surgery is a palliative surgery with good results. It significantly improves patient quality of life over a long period until a total cavopulmonary shunt is performed. The complications observed are few, and the mortality rate is low. Therefore, it is a safe surgery that should be used for univentricular congenital heart disease.

Resumen Introducción: El objetivo de este trabajo fue describir la experiencia de 35 años en un hospital de tercer nivel con pacientes cardiópatas con fisiología univentricular que fueron sometidos a cirugía de Glenn. Métodos: Se presenta un análisis retrospectivo de los pacientes sometidos a cirugía de Glenn. Se incluyeron variables relacionadas con la morbilidad y la mortalidad preoperatorias, transoperatorias y posoperatorias. Resultados: Desde 1980 hasta 2015 se realizaron 204 cirugías de Glenn para la corrección de cardiopatías. De ellas, la más frecuente fue la atresia tricuspídea IB (19.2%); en el 48.1% se realizó Glenn con flujo anterógrado, en el 12.5% Glenn bilateral y el 10.3% de las cirugías fueron sin apoyo de bomba de circulación extracorpórea. Las complicaciones reportadas fueron infecciones, sangrado, arritmias, quilotórax, alteraciones neurológicas y derrame pleural. La mortalidad fue del 2.9%. Conclusiones: La cirugía de Glenn es un procedimiento paliativo que se ha utilizado con buenos resultados. Mejora en forma importante la calidad de vida del paciente durante un largo periodo mientras que se realiza la derivación cavopulmonar total. Presenta pocas complicaciones y muy baja mortalidad, por lo que es una cirugía segura que debe ser utilizada para cardiopatías congénitas univentriculares.

Angiotensin-converting enzyme inhibition and pre-superior cavopulmonary connection haemodynamics in infants with single-ventricle physiology.

INTRODUCTION: Preliminary animal and human data suggest that angiotensin-converting enzyme inhibition has a role in pulmonary vascular remodelling. We sought to assess the effect of ACEi versus placebo on pulmonary artery pressure and transpulmonary gradient amongst infants undergoing single-ventricle palliation. MATERIALS AND METHODS: Using the publicly available Pediatric Heart Network Infant Single-Ventricle trial dataset, we compared mean PA pressure at pre-superior cavopulmonary connection catheterisation (primary outcome), transpulmonary gradient, pulmonary-to-systemic flow ratio, and post-SCPC oxygen saturation (secondary outcomes) in infants receiving enalapril versus placebo. RESULTS: A total of 179 infants underwent pre-SCPC catheterisation, of which 85 (47%) received enalapril. There was no difference between the enalapril and placebo group in the primary and the secondary outcomes. Mean PA pressure in the enalapril group was 13.1 ± 2.9 compared to 13.7 ± 3.4 mmHg in the placebo group. The transpulmonary gradient was 6.7 ± 2.5 versus 6.9 ± 3.2 mmHg in the enalapril and placebo groups, respectively. The pulmonary-to-systemic flow ratio was 1.1 ± 0.5 in the enalapril group versus 1.0 ± 0.5 in the placebo group and the post-SCPC saturation was 83.1 ± 5.0% in the enalapril group versus 82.2 ± 5.3% in the placebo group. In the pre-specified subgroup analyses comparing enalapril and placebo according to ventricular morphology and shunt type, there was no difference in the primary and secondary outcomes. CONCLUSION: ACEi did not impact mean pulmonary artery pressure or transpulmonary gradient amongst infants with single-ventricle physiology prior to SCPC palliation.