Pulmonary Vasodilator Therapy in Children with Single Ventricle Physiology: Effects on Saturation and Pulmonary Arterial Pressure

The single ventricle presenting late: surgical options

The term single ventricle (SV) comprises a wide variety of congenital anomalies with a structurally or functionally univentricular heart where a biventricular repair is not possible or undesirable. The surgical management of these patients is often staged and the ultimate palliation is the Fontan operation (FO). Despite advances in surgical techniques, significant challenges persist in the management of SV patients, particularly in low- and middle-income countries (LMICs), where delayed presentation and limited healthcare access are common. This review explores current management strategies for patients beyond childhood, including those who have never undergone palliation and post-Fontan patients facing long-term complications. Key topics include the surgical approaches to SV, such as pulmonary artery banding (PAB), bidirectional Glenn (BDG), and FO, with particular focus on considerations for late-presenting adults in LMICs. The disparities in healthcare resources between high-income countries and LMICs are highlighted, demonstrating that resource constraints significantly impact timely interventions and on-going follow-up care.

Hypoplastic Left Heart Syndrome Practice Variation Across 31 Centres From 20 European Countries. An AEPC Imaging Working Group Study

Despite significant advances in knowledge and the development of guidelines, the management of hypoplastic left heart syndrome (HLHS) remains highly variable. A structured questionnaire was circulated across European Association of Paediatric & Congenital Cardiology (AEPC) affiliated centres. The aims were to evaluate standards in pre-operative assessment, types of surgery, follow-up and medical practices in children with HLHS. Thirty-one centres from 20 countries completed the survey. Delivery of babies with HLHS occurred in co-located maternity hospitals in 74% of centres; 29% were planned for spontaneous onset of labour, while 54% decided on a case-by-case basis. The preferred initial palliation was a right ventricle-pulmonary artery conduit in 55% of cases, modified Blalock-Thomas Taussig shunt (mBTTS) in 35%, and hybrid in 15% of cases. Timing for Glenn varied from 3 to 6 months of age and preoperative examination varied greatly: 65% performed cardiac catheterization and only 19% performed cardiac magnetic resonance. Stage III palliation was performed at a highly variable interval (2-6 years of age), nearly always employing an extracardiac conduit. Fenestration was routinely performed in 61% and reserved for borderline cases in 39%. All the centers adopted warfarin for the first 3-12 months after Fontan completion, and continued if a fenestration was present, while in non-fenestrated aspirin was left by most centers (e.g. 68%). However, there was a high disparity in the use of heart failure medications (e.g. in interstage I-II 35% use ACE-inhibitors, and only 26% digoxin). Follow-up practice also varied widely with only 60% employing specific protocols.

CONCLUSION

 This first multi-centre European survey from 31 centres from 20 different European countries highlighted a high practice variation in HLHS management across all the stages of Single Ventricle (Fontan) palliation. Major variations pertained to pre- and post-surgical investigations, surgical strategy for stage I and III, medical treatment regimens, and follow-up programs.

WHAT IS KNOWN

• Hypoplastic left heart syndrome (HLHS) remains one of the most complex and challenging congenital cardiac defects to manage. • Investigating the management of children with HLHS across different European centres can facilitate study of the most effective management strategies.

WHAT IS NEW

• Significant variation in HLHS management were reported in relation to pre- and post-surgical examinations, surgical strategy at stage I and III, medical treatment regimens, and follow-up programs. • Greater standardisation of imaging and diagnostic evaluation, medical treatment and follow-up surveillance may improve outcomes for these vulnerable patients and warrants further study.

The Use of Pulmonary Vasodilators in Pediatric Patients with Single-Ventricle Palliation: A Ten-Year Experience in a Tertiary Care Center

In single-ventricle circulation, pulmonary vascular resistances (PVR) play a crucial role at various stages of surgical palliation. Increased PVR detected at cardiac catheterization represents a contraindication to Fontan completion and may lead to an early circuit failure in the postoperative period. Pulmonary vasodilator therapy (PVT) may lower PVR and enhance pre- and post-surgical outcomes in Fontan patients. This study reports the experience with the use of PVT in a tertiary center, focusing on its role in lowering PVR before Fontan procedure and assessing its impact on postoperative outcomes. We analyzed 151 pediatric patients with single-ventricle heart diseases in pre-Fontan stage at our institution from January 2014 to December 2023, collecting demographics, anatomical diagnoses, clinical history, administration of PVT, surgical complications, pre-Fontan hemodynamic parameters, duration of intubation, chest tube retention, oxygen therapy needs, and total hospitalization time. In 17 out of 18 patients (94.4%) who were previously considered unsuitable for Fontan completion, a significant decrease in PVR (p = 0.006) was observed after starting PVT, enabling surgery to be performed. Among 113 patients (74.8%) undergoing Fontan, no differences in postoperative outcomes were observed between those who received PVT in the pre-Fontan stage and those who did not. PVT was started in 50 out of 113 patients (44.2%) after surgery, primarily due to elevated pulmonary pressures on invasive monitoring; among them, 24 patients (48%) had already been on therapy prior to the operation. PVT in the postoperative period was associated with worse outcomes compared to patients not receiving therapy, likely due to the more severe conditions of treated patients. The use of PVT during the pre-Fontan stage increases the number of individuals eligible for surgical palliation, with minimal impact on postoperative outcomes.

The effects of standardized intravenous treprostinil in pulmonary arterial hypertension patients after total cavo-pulmonary connection procedure

OBJECTIVE

Total cavo-pulmonary connection (TCPC) is a palliative treatment for single ventricular malformations. For high-risk patients (preoperative mean pulmonary arterial pressure, mPAP > 15 mmHg), between the inhaled and oral targeted medications, the application of intravenous treprostinil as a bridge therapy to achieve "seamless" management is core postoperative treatment. This study intends to explore the effect of different administration regimens on early postoperative recovery.

METHODS

This was a retrospective cohort study. High-risk pediatric patients (age ≤ 14 years) who underwent TCPC procedure in Fu Wai Hospital from 2015 to 2022 were included. Since the regimen of treprostinil was standardized in our center in 2021, the patients in 2020 and before were included in group 1, patients in 2021 and 2022 were included in group 2. The hemodynamic parameters were compared before and after the maintenance dose of treprostinil. The differences of demographic characteristics, surgical data and postoperative recovery were compared between the two groups.

RESULTS

A total of 51 pediatric patients were included. Group 1 included 35 patients who received treprostinil at 1-3 postoperative days and an average dose of 12 ± 4 ng/(kg·min). Group 2 included 16 patients who received treprostinil within postoperative 1 day and an average dose of 22 ± 7 ng/(kg·min). There were no significant differences between the two groups in terms of age, weight, preoperative percutaneous oxygen saturation and mPAP,  heterotaxy syndrome, TCPC procedure type, other concurrent procedure, cardiopulmonary bypass time and aortic cross-clamp proportion (p > 0.05). After 24 h of treprostinil treatment, the mPAP in group 1 reduced from 17 ± 3 mmHg to 15 ± 2 mmHg (p < 0.001), and in group 2 from 17 ± 2 mmHg to 14 ± 2 mmHg (p < 0.001), with no difference between groups. In the postoperative recovery, patients in Group 2 exhibited a reduced duration of mechanical ventilation, 19 (11, 25) hours vs 69 (23, 189) hours, p = 0.001; a shorter stay in the ICU, 8 (6, 12) days vs 16 (9,26) days, p = 0.006; and a shorter postoperative length of stay, 27 (17,55) days vs 39 (29,58) days, p = 0.032. Patients in Group 2 also exhibited a lower incidence of thromboembolic events, 0 (0/26) vs 26% (9/35), p = 0.043; and the need for renal replacement therapy, 0 (0/26) vs 31% (11/35), p = 0.011.

CONCLUSION

Treprostinil reduces pulmonary artery pressure after TCPC procedure. The standardized application of treprostinil may improve the postoperative recovery which should be proven by randomized controlled trials or matched cohort studies in the future.

Decreased erythrocyte aggregation in Glenn and Fontan: univentricular circulation as a rheologic disease model

BACKGROUND

In the Fontan palliation for single ventricle heart disease (SVHD), pulmonary blood flow is non-pulsatile/passive, low velocity, and low shear, making viscous power loss a critical determinant of cardiac output. The rheologic properties of blood in SVHD patients are essential for understanding and modulating their limited cardiac output and they have not been systematically studied. We hypothesize that viscosity is decreased in single ventricle circulation.

METHODS

We evaluated whole blood viscosity, red blood cell (RBC) aggregation, and RBC deformability to evaluate changes in healthy children and SVHD patients. We altered suspending media to understand cellular and plasma differences contributing to rheologic differences.

RESULTS

Whole blood viscosity was similar between SVHD and healthy at their native hematocrits, while viscosity was lower at equivalent hematocrits for SVHD patients. RBC deformability is increased, and RBC aggregation is decreased in SVHD patients. Suspending SVHD RBCs in healthy plasma resulted in increased RBC aggregation and suspending healthy RBCs in SVHD plasma resulted in lower RBC aggregation.

CONCLUSIONS

Hematocrit corrected blood viscosity is lower in SVHD vs. healthy due to decreased RBC aggregation and higher RBC deformability, a viscous adaptation of blood in patients whose cardiac output is dependent on minimizing viscous power loss.

IMPACT

Patients with single ventricle circulation have decreased red blood cell aggregation and increased red blood cell deformability, both of which result in a decrease in blood viscosity across a large shear rate range. Since the unique Fontan circulation has very low-shear and low velocity flow in the pulmonary arteries, blood viscosity plays an increased role in vascular resistance, therefore this work is the first to describe a novel mechanism to target pulmonary vascular resistance as a modifiable risk factor. This is a novel, modifiable risk factor in this patient population.

Impact of Udenafil on Echocardiographic Indices of Single Ventricle Size and Function in FUEL Study Participants

BACKGROUND

The FUEL trial (Fontan Udenafil Exercise Longitudinal) demonstrated statistical improvements in exercise capacity following 6 months of treatment with udenafil (87.5 mg po BID). The effect of udenafil on echocardiographic measures of single ventricle function in this cohort has not been studied.

METHODS

The 400 enrolled participants were randomized 1:1 to udenafil or placebo. Protocol echocardiograms were obtained at baseline and 26 weeks after initiation of udenafil/placebo. Linear regression compared change from baseline indices of single ventricle systolic, diastolic and global function, atrioventricular valve regurgitation, and mean Fontan fenestration gradient in the udenafil cohort versus placebo, controlling for ventricular morphology (left ventricle versus right ventricle/other) and baseline value.

RESULTS

The udenafil participants (n=191) had significantly improved between baseline and 26 weeks visits compared to placebo participants (n=195) in myocardial performance index (P=0.03, adjusted mean difference [SE] of changes between groups -0.03[0.01]), atrioventricular valve inflow peak E (P=0.009, 3.95 [1.50]), and A velocities (P=0.034, 3.46 [1.62]), and annular Doppler tissue imaging-derived peak e' velocity (P=0.008, 0.60[0.23]). There were no significant differences in change in single ventricle size, systolic function, atrioventricular valve regurgitation severity, or mean fenestration gradient. Participants with a dominant left ventricle had significantly more favorable baseline values of indices of single ventricle size and function (lower volumes and areas, E/e' ratio, systolic:diastolic time and atrioventricular valve regurgitation, and higher annular s' and e' velocity).

CONCLUSIONS

FUEL participants who received udenafil demonstrated a statistically significant improvement in some global and diastolic echo indices. Although small, the changes in diastolic function suggest improvement in pulmonary venous return and/or augmented ventricular compliance, which may help explain improved exercise performance in that cohort.

REGISTRATION

URL: https://clinicaltrials.gov; Unique Identifier: NCT02741115.

Subcutaneous Treprostinil Improves Surgical Candidacy for Next Stage Palliation in Single Ventricle Patients With High-Risk Hemodynamics

Single ventricle (SV) patients with pulmonary vascular disease (SV-PVD) are considered poor surgical candidates for Glenn or Fontan palliation. Given limited options for Stage 1 (S1) and Stage 2 (S2) SV patients with SV-PVD, we report on the use of subcutaneous treprostinil (TRE) to treat SV-PVD in this population. This single-center, retrospective cohort study examined SV patients who were not candidates for subsequent surgical palliation due to SV-PVD and were treated with TRE. The primary outcome was ability to progress to the next surgical stage; secondary outcomes included changes in hemodynamics after TRE initiation. Between 3/2014 and 8/2021, 17 SV patients received TRE for SV-PVD: 11 after S1 and 6 after S2 (median PVR 4.1 [IQR 3.2-4.8] WU*m2 and 5.0 [IQR 1.5-6.1] WU*m2, respectively). Nine of 11 (82%) S1 progressed to S2, and 2 (18%) underwent heart transplant (HTx). Three of 6 (50%) S2 progressed to Fontan, 1 underwent HTx and 2 are awaiting Fontan on TRE. TRE significantly decreased PVR in S1 patients with median post-treatment PVR of 2.0 (IQR 1.5-2.6) WU*m2. TRE can allow for further surgical palliation in select pre-Fontan patients with SV-PVD, obviating the need for HTx. Improvement in PVR was significant in S1 patients and persisted beyond discontinuation of therapy for most patients.

Current evidence for pharmacologic therapy following stage 1 palliation for single ventricle congenital heart disease

INTRODUCTION

Infants with single ventricle congenital heart disease are vulnerable to complications between stage 1 and stage 2 of palliation. Pharmaceutical treatment during this period is varied and often dependent on institutional practices as there is little evidence supporting a particular treatment path.

AREAS COVERED

This review focuses on medical management of patients following stage I palliation. We performed a scoping review of the current literature regarding angiotensin converting enzyme inhibitors and digoxin treatment in the interstage period. In addition, we discuss other medication classes frequently used in these patients.

EXPERT OPINION

Due to significant heterogeneity of anatomy, rarity of disease, and other confounding factors, there is limited evidence to support most commonly used medications within the interstage period. Digoxin is associated with improved mortality within the interstage period and should be considered; however, no large randomized controlled trial exists supporting its use. Prevention of thrombotic complication with aspirin is also associated with improved outcomes and should be considered unless a contraindication exists. The addition of other prescriptions in this patient population should be considered only after an evaluation of the risks and benefits of each medication, recognizing the burden and risk of polypharmacy in this fragile patient population.

Congenital Heart Disease: The State-of-the-Art on Its Pharmacological Therapeutics

Congenital heart disease is one of the most common causes of death derived from malformations. Historically, its treatment has depended on timely diagnosis and early pharmacological and surgical interventions. Survival rates for patients with this disease have increased, primarily due to advancements in therapeutic choices, but mortality remains high. Since this disease is a time-sensitive pathology, pharmacological interventions are needed to improve clinical outcomes. Therefore, we analyzed the applications, dosage, and side effects of drugs currently used for treating congenital heart disease. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, and potassium-sparing diuretics have shown a mortality benefit in most patients. Other therapies, such as endothelin receptor antagonists, phosphodiesterase-5 inhibitors, prostaglandins, and soluble guanylyl cyclase stimulators, have benefited patients with pulmonary artery hypertension. Likewise, the adjunctive symptomatic treatment of these patients has further improved the outcomes, since antiarrhythmics, digoxin, and non-steroidal anti-inflammatory drugs have shown their benefits in these cases. Conclusively, these drugs also carry the risk of troublesome adverse effects, such as electrolyte imbalances and hemodynamic compromise. However, their benefits for survival, symptom improvement, and stabilization outweigh the possible complications from their use. Thus, cases must be assessed individually to accurately identify interventions that would be most beneficial for patients.

Vasodilator therapy for pulmonary hypertension in children: a national study of patient characteristics and current treatment strategies

Pulmonary vasodilator therapy is still often an off-label treatment for pulmonary hypertension in children. The aim of this nationwide register-based study was to assess patient characteristics and strategies for pulmonary vasodilator therapy in young Swedish children. Prescription information for all children below seven years of age at treatment initiation, between 2007 and 2017, was retrieved from the National Prescribed Drug Register, and medical information was obtained by linkage to other registers. All patients were categorized according to the WHO classification of pulmonary hypertension. In total, 233 patients had been prescribed pulmonary vasodilators. The treatment was initiated before one year of age in 61% (N = 143). Sildenafil was most common (N = 224 patients), followed by bosentan (N = 29), iloprost (N = 14), macitentan (N = 4), treprostinil (N = 2) and riociguat (N = 2). Over the study period, the prescription rate for sildenafil tripled. Monotherapy was most common, 87% (N = 203), while 13% (N = 20) had combination therapy. Bronchopulmonary dysplasia (N = 82, 35%) and/or congenital heart defects (N = 156, 67%) were the most common associated conditions. Eight percent (N = 18) of the patients had Down syndrome. Cardiac catheterization had been performed in 39% (N = 91). Overall mortality was 13% (N = 30) during the study period. This study provides an unbiased overview of national outpatient use of pulmonary vasodilator therapy in young children. Few cases of idiopathic pulmonary arterial hypertension were found, but a large proportion of pulmonary hypertension associated with congenital heart defects or bronchopulmonary dysplasia. Despite treatment, mortality was high, and additional pediatric studies are needed for a better understanding of underlying pathologies and evidence of treatment effects.

Factors influencing length of intensive care unit stay following a bidirectional cavopulmonary shunt

 

OBJECTIVES

The goal of this study was to identify the risk factors for prolonged length of stay (LOS) in the intensive care unit (ICU) after a bidirectional cavopulmonary shunt (BCPS) procedure and its impact on the number of deaths.

METHODS

In total, 556 patients who underwent BCPS between January 1998 and December 2019 were included in the study.

RESULTS

Eighteen patients died while in the ICU, and 35 died after discharge from the ICU. Reduced ventricular function was significantly associated with death during the ICU stay (P = 0.002). In patients who were discharged alive from the ICU, LOS in the ICU [hazard ratio (HR) 1.04, 95% confidence interval (CI) 1.02-1.06; P < 0.001] and a dominant right ventricle (HR 2.41, 95% CI 1.03-6.63; P = 0.04) were independent risk factors for death. Receiver operating characteristic analysis identified a cut-off value for length of ICU stay of 19 days. Mean pulmonary artery pressure (HR 1.03, 95% CI 1.01-1.05; P = 0.04) was a significant risk factor for a prolonged ICU stay.

CONCLUSIONS

Prolonged LOS in the ICU with a cut-off value of 19 days after BCPS was a significant risk factor for mortality. High pulmonary artery pressure at BCPS was a significant risk factor for a prolonged ICU stay.