Outcomes in Patients with Persistent Ventricular Dysfunction After Stage I Palliation for Hypoplastic Left Heart Syndrome

Outcomes of Children With Hypoplastic Left Heart Syndrome and Heart Failure on Medical Therapy

Background

Systemic right ventricle (RV) dysfunction is associated with lower transplant-free survival (TFS) in hypoplastic left heart syndrome (HLHS), but the likelihood of functional improvement and utility of heart failure (HF) medications is not understood.

Objectives

The authors aimed to describe TFS, HF medication use, and surgical interventions in HLHS patients with RV dysfunction with and without subsequent improvement in function.

Methods

The SickKids HF Database is a retrospective cohort that includes all pediatric HLHS patients with RV dysfunction lasting >30 days. We compared TFS, HF medications, and surgical interventions in HLHS patients with and without functional normalization.

Results

Of 99 patients with HLHS and RV dysfunction, 52% had normalized function for ≥30 days. TFS at 2 years after dysfunction onset was lower in those without normalization (14% vs 78%, P < 0.001). Patients without normalization were less likely to reach target dosing (TD) of HF medications (27% vs 47% on 1 medication at TD, P < 0.001) and undergo Fontan completion (7% vs 53%, P < 0.001). Clinical factors associated with improved TFS were normalization of function for ≥30 days, onset of dysfunction after bidirectional Glenn, and exposure to ACE inhibition.

Conclusions

Our cohort of HLHS patients with systemic RV dysfunction demonstrated a novel finding of improved TFS in those with functional normalization for ≥30 days. Achieving TD of HF medications was associated with improved outcomes. This may reflect patient stability and tolerance for HF medication more than its therapeutic effect, but it can help inform decisions to proceed with surgical palliation or list for transplant.

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.

Periscopic technique in Norwood operation is associated with better preservation of early ventricular function

Objective

Although the right ventricle (RV) to pulmonary artery conduit in stage 1 Norwood operation results in improved interstage survival, the long-term effects of the ventriculotomy used in the traditional technique remain a concern. The periscopic technique (PT) of RV to pulmonary artery conduit placement has been described as an alternative technique to minimize RV injury. A retrospective study was performed to compare the effects of traditional technique and PT on ventricular function following Norwood operation.

Methods

A retrospective study of all patients who underwent Norwood operation from 2012 to 2019 was performed. Patients with baseline RV dysfunction and significant tricuspid valve regurgitation were excluded. Prestage 2 echocardiograms were reviewed by a blinded experienced imager for quantification of RV function (sinus and infundibular RV fractional area change) as well as for regional conduit site wall dysfunction (normal or abnormal, including hypokinesia, akinesia, or dyskinesia). Wilcoxon rank-sum tests were used to assess differences in RV infundibular and RV sinus ejection fraction and the Fisher exact test was used to assess differences in regional wall dysfunction.

Results

Twenty-two patients met inclusion criteria. Eight underwent traditional technique and 14 underwent PT. Median infundibular RV fractional area change was 49% and 37% (P = .02) and sinus RV fractional area change was 50% and 41% for PT and traditional technique (P = .007) respectively. Similarly qualitative regional RV wall function was better preserved in PT (P = .002).

Conclusions

The PT for RV to pulmonary artery conduit in Norwood operation results in better preservation of early RV global and regional systolic function. Whether or not this benefit translates to improved clinical outcome still needs to be studied.

Impact of Lactate Clearance on Early Outcomes in Pediatric ECMO Patients

Background and Objectives: Pediatric extracorporeal membrane oxygenation (ECMO) support is often the ultimate therapy for neonatal and pediatric patients with congenital heart defects after cardiac surgery. The impact of lactate clearance in pediatric patients during ECMO therapy on outcomes has been analyzed. Materials andMethods: We retrospectively analyzed data from 41 pediatric vaECMO patients between January 2006 and December 2016. Blood lactate and lactate clearance have been recorded prior to ECMO implantation and 3, 6, 9 and 12 h after ECMO start. Receiver operating characteristic (ROC) analysis was used to identify cut-off levels for lactate clearance. Results: Lactate levels prior to ECMO therapy (9.8 mmol/L vs. 13.5 mmol/L; p = 0.07) and peak lactate levels during ECMO support (10.4 mmol/L vs. 14.7 mmol/L; p = 0.07) were similar between survivors and nonsurvivors. Areas under the curve (AUC) of lactate clearance at 3, 9 h and 12 h after ECMO start were significantly predictive for mortality (p = 0.017, p = 0.049 and p = 0.006, respectively). Cut-off values of lactate clearance were 3.8%, 51% and 56%. Duration of ECMO support and respiratory ventilation was significantly longer in survivors than in nonsurvivors (p = 0.01 and p < 0.001, respectively). Conclusions: Dynamic recording of lactate clearance after ECMO start is a valuable tool to assess outcomes and effectiveness of ECMO application. Poor lactate clearance during ECMO therapy in pediatric patients is a significant marker for higher mortality.

Postoperative heart failure after stage 1 palliative surgery for single ventricle cardiac disease

Outcomes for patients with single ventricle congenital heart disease (SV-CHD) continue to improve over time. However, the prognosis for patients who develop heart failure immediately after surgery is poorly understood. We conducted a single-center, retrospective cohort study of patients with SV-CHD, who suffered postoperative heart failure. Of 1038 cardiac surgeries performed on 621 SV-CHD patients between 2004 and 2010, 125 patients met inclusion criteria, including non-septatable anatomy, stage 1 surgery, and verified low cardiac output or heart failure state per STS definition. Overall survival was 73.2% at 2 months, 64.9% at 1 year, 60.5% at 2 years, and 54.6% at 4 years. Inotrope dependence beyond 7 days post-op yielded 45% 2-year survival versus 68% for those who weaned from inotropes within 7 days (p = 0.02). Atrioventricular valve regurgitation (AVVR) influenced survival, and patients who developed renal failure or required ECMO fared poorly, even when they survived their hospitalization. Patients with postoperative heart failure and low cardiac output syndrome constitute a high-risk population beyond the term of the initial hospitalization and have an overall mid-term survival of 55% at 4 years. Wean from inotropic therapy is not completely reassuring in this population, as they have ongoing elevated risk of cardiac failure and death in the medium term. Ventricular dysfunction, AVVR, renal failure, and need for ECMO are all important prognostic factors for mid-term mortality. Inotrope dependence for > 7 days has important implications reaching beyond the hospitalization.

Hand-held echocardiography in children with hypoplastic left heart syndrome

BACKGROUND

When performed by cardiologists, hand-held echocardiography (HHE) can assess ventricular systolic function and valve disease in adults, but its accuracy and utility in congenital heart disease is unknown. In hypoplastic left heart syndrome (HLHS), the echocardiographic detection of depressed right ventricular (RV) systolic function and higher grade tricuspid regurgitation (TR) can identify patients who are at increased risk of morbidity and mortality and who may benefit from additional imaging or medical therapies.

METHODS

Children with HLHS after Stage I or II surgical palliation (Norwood or Glenn procedures) were prospectively enrolled. Subjects underwent HHE by a pediatric cardiologist on the same day as standard echocardiography (SE). Using 4-point scales, bedside HHE assessment of RV systolic function and TR were compared with blinded assessment of offline SE images. Concordance correlation coefficient (CCC) was used to evaluate agreement.

RESULTS

Thirty-two HHEs were performed on 15 subjects (Stage I: n = 17 and Stage II: n = 15). Median subject age was 3.4 months (14 days-4.2 years). Median weight was 5.9 kg (2.6-15.4 kg). Bedside HHE assessment of RV systolic function and TR severity had substantial agreement with SE (CCC = 0.80, CCC = 0.74, respectively; P < .001). HHE sensitivity and specificity for any grade of depressed RV systolic function were 100% and 92%, respectively, and were 94% and 88% for moderate or greater TR, respectively. Average HHE scan time was 238 seconds.

CONCLUSIONS

HHE offers a rapid, bedside tool for pediatric cardiologists to detect RV systolic dysfunction and hemodynamically significant TR in HLHS.

Serial Strain Analysis Identifies Hypoplastic Left Heart Syndrome Infants at Risk for Cardiac Morbidity and Mortality: A Pilot Study

BACKGROUND

Validated, objective measures of right ventricular (RV) function assessment in hypoplastic left heart syndrome (HLHS) are needed. In other populations, speckle-tracking echocardiography-derived strain is a sensitive measure that outperforms conventional parameters of RV function. We hypothesized that speckle-tracking echocardiography-derived measures of RV function would be worse in patients with HLHS who have a poor cardiac outcome.

METHODS

Prospective serial echocardiography was performed in 35 infants with HLHS during the first 6 months of life. Patients not undergoing staged palliation or with other variants of single RV were excluded. Traditional RV measurements and strain analysis were performed from standard apical and basal views. The primary outcome of cardiac death, heart transplantation, or persistent ≥ moderate RV dysfunction was examined using Cox regression analysis, and receiver operating characteristic curve analyses were performed to derive cutoff values.

RESULTS

At median follow-up of 10.9 months (interquartile range 5.6, 15.2), eight patients reached the outcome and demonstrated worse RV strain measures compared with those without the outcome. A post-Norwood global longitudinal strain (GLS) of > -16% (area under the curve [AUC] = 0.76; P = .04) and pre-Glenn GLS > -13% (AUC, 0.98; P ≤ .01) were highly sensitive and specific for poor outcome. Other thresholds included post-Norwood GLS rate (GLSr) > -1.15 %/s (AUC, 0.78; P = .03), pre-Glenn GLSr = -0.85%/sec (AUC, 0.89; P < .01), post-Glenn circumferential strain rate > -0.85%/sec (AUC, 0.92; P < .01), and GLSr > -0.85%/sec (AUC, 0.84; P = .02).

CONCLUSIONS

Strain analysis may help identify at-risk HLHS infants. In this pilot study, interstage strain indices were worse in infants with HLHS who had a poor cardiac outcome.

Systemic Ventricular Dysfunction Between Stage One and Stage Two Palliation

Infants with a single ventricle can develop systemic ventricular dysfunction (SVD) after stage 1 operation, but available information is sparse. We reviewed our patients having Norwood, Sano, or hybrid procedures to better understand this problem. We conducted a retrospective, case-controlled cohort study of 267 patients having stage1 operation, examining outcomes between stages 1 and 2 (survival and subsequent cardiac surgeries), predictor variables, and histology of hearts explanted at transplantation. SVD developed in 32 (12%) patients and resolved in 13 (41%); mean age of onset was 3.0 ± 1.63 months; median = 2.79. SVD was not associated with cardiac anatomy, type of stage 1 procedure, weight, coronary abnormality, or atrioventricular valve regurgitation. The mean age of resolution = 12.1 ± 9.6 months; median = 6.3, and resolution may have been more likely with a systemic LV than RV (p = 0.067). Outcomes for the entire SVD group were less favorable than for those without, but patients with resolution of SVD had outcomes at least as good those without SVD. Myocardial histology (n = 4) suggested chronic ischemia. The risk of SVD after stage 1, while low, may be a fundamental feature of this patient population. SVD occurs with either a systemic RV or LV, although patients with a systemic LV may be more likely to have resolution than those with an RV. We identified no predictor variables, but histologic findings suggest chronic ischemia may be involved. Given the low incidence of SVD, multi-center studies will be required to better define predictors of onset and resolution.

Survival to Stage II with Ventricular Dysfunction: Secondary Analysis of the Single Ventricle Reconstruction Trial

Ventricular dysfunction affects survival in patients with single right ventricle (RV), and remains one of the primary indications for heart transplantation. Since it is challenging to predict the capacity of patients with ventricular dysfunction to proceed to the stage II procedure, we sought to identify factors that would be associated with death or heart transplantation without achieving stage II for single RV patients with ventricular dysfunction after Norwood procedure. The Single Ventricle Reconstruction (SVR) trial public-use database was used. Patients with a RV ejection fraction less than 44% or a RV fractional area of change less than 35% on the post-Norwood echocardiogram were included. Parametric risk hazard analysis was used to identify risk factors for death or transplantation without achieving stage II. Of 365 patients with ventricular function measurements on the post-Norwood echocardiogram, 123 (34%) patients had RV dysfunction. The transplantation-free survival was significantly lower for those with ventricular dysfunction compared to those with normal function (log rank Chi-square = 4.23, p = 0.04). Furthermore, having a Blalock-Taussig (BT) shunt, a large RV, a post-Norwood infectious complication, and a surgeon who performs five or less Norwood per year were independent risk factors for death or transplantation without achieving stage II. The predicted 6-month transplantation-free survival for patients with all four identified risk factors was 1% (70% CI 0-13%). Early heart transplantation referral might be considered for post-Norwood patients with BT shunt and RV dysfunction, especially if other high-risk features are present.

The Optimal Timing of Stage-2-Palliation After the Norwood Operation

BACKGROUND

The effect of the timing of stage-2-palliation (S2P) on survival through single ventricle palliation remains unknown. This study investigated the optimal timing of S2P that minimizes pre-S2P attrition and maximizes post-S2P survival.

METHODS

The Congenital Heart Surgeons' Society's critical left ventricular outflow tract obstruction cohort was used. Survival analysis was performed using multiphase parametric hazard analysis. Separate risk factors for death after the Norwood and after S2P were identified. Based on the multivariable models, infants were stratified as low, intermediate, or high risk. Cumulative 2-year, post-Norwood survival was predicted. Optimal timing was determined using conditional survival analysis and plotted as 2-year, post-Norwood survival versus age at S2P.

RESULTS

A Norwood operation was performed in 534 neonates from 21 institutions. The S2P was performed in 71%, at a median age of 5.1 months (IQR: 4.3 to 6.0), and 22% died after Norwood. By 5 years after S2P, 10% of infants had died. For low- and intermediate-risk infants, performing S2P after age 3 months was associated with 89% ± 3% and 82% ± 3% 2-year survival, respectively. Undergoing an interval cardiac reoperation or moderate-severe right ventricular dysfunction before S2P were high-risk features. Among high-risk infants, 2-year survival was 63% ± 5%, and even lower when S2P was performed before age 6 months.

CONCLUSIONS

Performing S2P after age 3 months may optimize survival of low- and intermediate-risk infants. High-risk infants are unlikely to complete three-stage palliation, and early S2P may increase their risk of mortality. We infer that early referral for cardiac transplantation may increase their chance of survival.

Cavopulmonary Anastomosis During Same Hospitalization as Stage 1 Norwood/Hybrid Palliative Surgery

BACKGROUND

Limited literature has examined characteristics of infants with hypoplastic left heart syndrome (HLHS) who remain hospitalized during the interstage period. We described their epidemiologic characteristics, in-hospital outcomes, and identified risk factors that predict the need for superior cavopulmonary anastomosis (SCPA) during the same hospitalization.

METHODS

This retrospective multicenter database analysis included infants with HLHS who underwent stage 1 palliation from 2004 through 2013.

RESULTS

Among 5374 infants with HLHS, 314 (5.8%) underwent SCPA during the same hospitalization as stage 1 palliation. They had a higher incidence of baseline comorbidities, complications, and interventions than infants who were discharged. Despite an overall increase in need for SCPA in the same hospitalization across different eras, there was no significant statistical difference in mortality in the two groups in the same era. Septicemia, necrotizing enterocolitis, modified Blalock-Taussig shunt, cardiac catheterization, cardiopulmonary resuscitation, extracorporeal membrane oxygenation, gastrostomy tube, and antiarrhythmic agents were independently associated with increased odds of undergoing SCPA during the same hospitalization. Patients undergoing right ventricle to pulmonary artery shunt were less likely to remain hospitalized until stage 2 palliation. Nonsurvivors in the SCPA group had greater need for interventions and worse intensive care unit outcomes.

CONCLUSIONS

Infants with HLHS who remain hospitalized after stage 1 until their stage 2 palliation differ significantly from infants who were discharged. Several clinical characteristics, comorbidities, and need for interventions are associated with the likelihood for undergoing stage 2 palliation during the same hospitalization. Timely identification and intervention of adjustable causes of heart failure may improve outcomes.

Mechanically assisted bidirectional cavopulmonary shunt in neonates and infants: An acute human pilot study

OBJECTIVE

Poor survival following surgical palliation for hypoplastic left heart syndrome (HLHS) raises the question of the need for a paradigm shift. This is the first human study to investigate the possibility of primary "in-series" palliation in neonates and infants with HLHS in an acute setting with the aid of 2 types of mechanical assist: superior vena cava (SVC)-to-pulmonary artery (PA) pump assist and SVC-to-right atrium (RA) oxygenation assist.

METHODS

By rearranging the cannula sites and flow rates for modified ultrafiltration, 2 types of mechanically assisted bidirectional cavopulmonary shunt (BCPS) circulation were simulated for 20 minutes. Three neonates undergoing a stage I Norwood procedure were assigned to SVC-PA pump assist, and 3 infants undergoing stage II BCPS were assigned to SVC-RA oxygenation assist. Hemodynamic parameters, blood gas values, and arterial (SaO₂) and regional cerebral tissue (rCTO₂) saturations were analyzed.

RESULTS

All 6 patients completed the study without hemodynamic compromise. In the SVC-PA pump assist group, a mean arterial pressure >40 mm Hg was maintained. SVC pressure was lower (P = .01) and cerebral perfusion pressure (CPP) was higher (P = .03) during the last 10 minutes of assist compared with Norwood physiology. SaO₂ >80%, rCTO₂ >60%, and mixed venous saturation ≥59% were maintained, comparable to values with Norwood physiology. In the SVC-RA oxygenation assist group, with full or 50% support, mean blood pressure >50 mm Hg, SVC pressure <15 mm Hg, mixed venous saturation >50%, and CPP >40 mm Hg were maintained, which were comparable to BCPS physiology.

CONCLUSIONS

Two types of mechanical assist to support primary in-series palliation are feasible in the acute setting. Both modes of mechanical assist maintained oxygenation, as well as systemic and cerebral perfusion.