Contemporary outcomes for functional single ventricle with total anomalous pulmonary venous connection

OBJECTIVE

In 2004, we reported improved early survival for patients with functional single ventricle anatomy and total anomalous pulmonary venous connection. This study sought to discover if outcomes have been ameliorated in the contemporary era.

METHODS

This was a single-center review of patients with single ventricle anatomy and total anomalous pulmonary venous connection who were admitted from 1984 to 2021. The cohort was divided into similarly sized groups by date of admission: Era 1: 1984 to 1992, Era 2: 1993 to 2007, and Era 3: 2008 to 2021. Survival was compared, and Cox proportional hazards models were used to evaluate the likelihood of mortality.

RESULTS

We included 190 patients with single ventricle anatomy and total anomalous pulmonary venous connection. Unbalanced atrioventricular canal defect (70%) was the most common primary diagnosis. The most common type of total anomalous pulmonary venous connection was supracardiac (49%). Approximately one-third (32%) of patients had pulmonary venous obstruction. There were no significant differences in patient characteristics across eras. Early survival after initial palliative operation improved between Eras 1 and 2, and then remained stable in Era 3. Overall survival improved from Era 1 to Eras 2 and 3 (P < .001), but not between Era 2 and 3. Survival to 10 years by Eras 1 to 3 was 15%, 51%, and 54%, respectively. The anatomic features associated with worse survival were hypoplastic left heart syndrome diagnosis (hazard ratio, 1.60; 1.04-2.57) and pulmonary venous obstruction (hazard ratio, 1.80; 1.24-2.69).

CONCLUSIONS

Overall survival for patients with single ventricle anatomy and total anomalous pulmonary venous connection has plateaued since the early 2000s. Even in the most recent era, survival to age 10 years remains less than 60%. Risk factors for mortality include the diagnosis of hypoplastic left heart syndrome and pulmonary venous obstruction. Further studies should focus on identification of the pathophysiological factors underlying the increased mortality.

Long-term incidence of arrhythmias in extracardiac conduit Fontan and comparison between systemic left and right ventricle

AIMS

The extracardiac conduit-Fontan (ECC) has become the preferred technique for univentricular heart palliation, but there are currently no data on the incidence of long-term arrhythmias. This study investigated the incidence of arrhythmias and relation to single ventricle morphology in the long-term follow-up (FU) in ECC.

METHODS AND RESULTS

All patients with ECC performed in our Centre between 1987 and 2017 were included (minimum FU 5 years). Of 353 consecutive patients, 303 [57.8% males, aging 8-50 (median 20) years at last FU] were considered and divided into two groups depending on left (194 in Group 1) or right (109 in Group 2) ventricular morphology. Eighty-five (28%) experienced ≥1 arrhythmic complications, with early and late arrhythmias in 17 (5.6%) and 73 (24.1%) patients, respectively. Notably, late bradyarrhythmias occurred after 6 years in 21 (11%) patients in Group 1, and in 15 (13.8%) in Group 2 [P = 0.48]. Late tachyarrhythmias occurred in 55 (18.2%) patients after 12 years: 33 (17%) in Group 1 and 22 (20.2%) patients in Group 2 [P  = 0.5]. Ventricular tachycardias (VT) were documented after 12.5 years in 14 (7.2%) patients of Group 1 and 15 (13.8%) of Group 2 [P = 0.06] with a higher incidence in Group 2 during the FU [P = 0.005].

CONCLUSION

Extracardiac conduit is related to a significant arrhythmic risk in the long-term FU, higher than previously reported. Bradyarrhythmias occur earlier but are less frequent than tachyarrhythmias. Interestingly, patients with systemic right ventricle have a significantly higher incidence of VT, especially in a very long FU.

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.

Predictive Models for Pulmonary Artery Size in Fontan Patients

We developed models of pulmonary artery (PA) size in Fontan patients as a function of age and body surface area (BSA) using linear regression and breakpoint analyses based on data from 43 Fontan patients divided into two groups: the extracardiac conduit (ECC) group (n = 24) and the non-ECC group (n = 19). Model predictions were compared against those of a non-Fontan control group (n = 18) and published literature. We observed strong positive correlations of the mean PA diameter with BSA (r = 0.9, p < 0.05) and age (r = 0.88, p < 0.05) in the ECC group. The absolute percentage differences between our BSA and age model predictions against published literature were less than 16% and 20%, respectively. Predicted PA size for Fontan patients was consistently smaller than the control group. These models may serve as useful references for clinicians and be utilized to construct 3D anatomic models that correspond to patient body size or age.

Total vascular resistance increases during volume-unloading in asymptomatic single ventricle patients

OBJECTIVE

While the surgical stages of single ventricle (SV) palliation serve to separate pulmonary venous and systemic venous return, and to volume-unload the SV, staged palliation also results in transition from parallel to series circulation, increasing total vascular resistance. How this transition affects pressure loading of the SV is as yet unreported.

METHODS

We performed a retrospective chart review of Stage I, II, and III cardiac catheterization (CC) and echocardiographic data from 2001-2017 in all SV pts, with focus on systemic, pulmonary, and total vascular resistance (SVR, PVR, TVR respectively). Longitudinal analyses were performed with log-transformed variables. Effects of SVR-lowering medications were analyzed using Wilcoxon rank-sum testing.

RESULTS

There were 372 total patients who underwent CC at a Stage I (median age of 4.4 months, n=310), Stage II (median age 2.7 years, n = 244), and Stage III (median age 7.3 years, n = 113). Total volume loading decreases with progression to Stage III (P< 0.001). While PVR gradually increases from Stage II to Stage III, and SVR increases from Stage I to Stage III, TVR dramatically increases with progress towards series circulation. TVR was not affected by use of systemic vasodilator therapy. TVR, PVR, SVR, and CI did not correlate with indices of SV function at Stage III.

CONCLUSIONS

TVR steadily increases with an increasing contribution from SVR over progressive stages. TVR was not affected by systemic vasodilator agents. TVR did not correlate with echo-based indices of SV function. Further studies are needed to see if modulating TVR can improve exercise tolerance and outcomes.

Assessment of pressure-volume relations in univentricular hearts: Comparison of obtainment by real-time 3D echocardiography and mini pressure-wire with conductance technology

Objectives

The gold standard to obtain pressure-volume relations (PVR) of the heart, the conductance technology (PVR_Cond), is rarely used in children. PVR can also be obtained by 3D-echocardiography volume data combined with simultaneously measured pressure data by a mini pressure-wire (PVR_3DE). We sought to investigate the feasibility of both methods in patients with univentricular hearts and to compare them, including hemodynamic changes.

Methods

We studied 19 patients (age 2–29 years). PVR_3DE and PVR_Cond were assessed under baseline conditions and stimulation with dobutamine.

Results

Obtaining PVR_3DE was successful in all patients. Obtaining PVR_Cond was possible in 15 patients during baseline (79%) and in 12 patients under dobutamine (63%). Both methods showed that end-systolic elastance (Ees) and arterial elastance (Ea) increased under dobutamine and that Tau showed a statistically significant decrease. Intraclass correlation (95% confidence interval) showed moderate to good agreement between methods: Ees: 0.873 (0.711–0.945), Ea: 0.709 (0.336–0.873), Tau: 0.867 (0.697–0.942). Bland-Altman analyses showed an acceptable bias with wider limits of agreement: Ees: 1.63 mmHg/ml (-3.83–7.08 mmHg/ml), Ea: 0.53 mmHg/ml (-5.23–6.28 mmHg/ml), Tau: -0,76 ms (-10.73–9.21 ms).

Conclusion

Changes of PVR-specific parameters under dobutamine stimulation were reflected in the same way by both methods. However, the absolute values for these parameters could vary between methods and, therefore, methods are not interchangeable. Obtaining PVR_3DE in a single ventricle was easier, faster and more successful than PVR_Cond. PVR_3DE provides a promising and needed alternative to the conductance technology for the assessment of cardiac function in univentricular hearts.

The impact of additional antegrade pulmonary blood flow at bidirectional Glenn shunt on long-term outcomes

OBJECTIVES

We investigated the impact of additional antegrade pulmonary blood flow on the long-term outcomes after bidirectional Glenn shunt.

METHODS

From 2001 to 2015, 279 patients underwent bidirectional Glenn shunt as an interim palliation for a functionally single ventricle. After excluding patients with a previous Kawashima or Norwood operation, 202 patients with preexisting antegrade pulmonary blood flow before bidirectional Glenn shunt were included in this study. Antegrade pulmonary blood flow was eliminated in 110 patients (no antegrade pulmonary blood flow group) and maintained in 92 patients (antegrade pulmonary blood flow group). The impact of antegrade pulmonary blood flow at bidirectional Glenn shunt on long-term outcome was analyzed using inverse probability of treatment weighting.

RESULTS

Median age and body weight at bidirectional Glenn shunt were 8 months and 7.8 kg, respectively. Prolonged chest tube drainage or readmission for effusion after bidirectional Glenn shunt was more frequent in the antegrade pulmonary blood flow group (odds ratio, 3.067; 95% confidence interval, 1.036-9.073; P = .043). In the no antegrade pulmonary blood flow group, B-type natriuretic peptide level was decreased further until the Fontan operation (P = .012). In the no antegrade pulmonary blood flow group, oxygen saturation was lower just after bidirectional Glenn shunt, although it was increased further until Fontan operation (P < .001), despite still lower oxygen saturation before Fontan operation compared with antegrade pulmonary blood flow group (P < .001). The McGoon ratio was decreased in both groups without intergroup difference, although the McGoon ratio before Fontan operation was higher in the antegrade pulmonary blood flow group (2.3 ± 0.4 vs 2.1 ± 0.4, P = .008). Overall transplant-free survival was worse in the antegrade pulmonary blood flow group (hazard ratio, 2.37; confidence interval, 1.089-5.152; P = .030).

CONCLUSIONS

Maintaining antegrade pulmonary blood flow at bidirectional Glenn shunt was beneficial for higher oxygen saturation and larger pulmonary artery size before Fontan operation. However, it was unfavorable for overall transplant-free survival with a sustained higher risk of death or transplant until the elimination of antegrade pulmonary blood flow.

A case of COVID-19 in a patient with a univentricular heart post total cavopulmonary connection (Fontan) surgery

Coronavirus disease 2019 (COVID-19) has caused a global pandemic which has affected patients and healthcare systems around the world. Patients with underlying health conditions seem to be more severely affected. There are limited reports of patients with univentricular circulations and COVID 19; thus, we report a case of COVID-19 in a patient with a univentricular circulation.

Major aortopulmonary collateral arteries in a case of unrepaired tricuspid and pulmonary atresia with single ventricle physiology

Tricuspid and pulmonary atresia with single ventricle physiology and major aortopulmonary collateral arteries (MAPCAs) is a complex cyanotic congenital heart disease with heterogeneous pulmonary artery morphology and arborization. The complex anatomy and physiology, coupled with a dearth of existing literature, pose imitable challenges to treatment. Although the exact surgical algorithm is still unclear, the goal is a well-developed, low-resistance pulmonary vascular bed. A precise understanding of the blood supply to each lung is a requisite for successful surgery, and a multimodality and multidisciplinary approach is compulsory. Herein, we describe a case of tricuspid and pulmonary atresia with single ventricle, MAPCAs and aortopulmonary collateral arteries.

Red Blood Cell Transfusion After Stage I Palliation Is Associated With Worse Clinical Outcomes

Background Packed red blood cell transfusion may improve oxygen content in single-ventricle neonates, but its effect on clinical outcomes after Stage 1 palliation is unknown. Methods and Results Retrospective multicenter analysis of packed red blood cell transfusion exposures in neonates after Stage 1 palliation, excluding those with intraoperative mortality or need for extracorporeal membrane oxygenation. Transfusion practice variability was assessed, and multivariable regression used to identify transfusion risk factors. After propensity score adjustment for severity of illness, clinical outcomes were compared between transfused and nontransfused subjects. Of 396 subjects, 323 (82%) received 930 postoperative red blood cell transfusions. Packed red blood cell volume (median 9-42 mL/kg [P<0.0001]), donor exposures (1-2 [P<0.0001]), transfusion number (1-3 [P<0.0001]), and pretransfusion hemoglobin (12.1-13 g/dL, P=0.0049) varied between sites. Cyanosis (P=0.02), chest tube output (P=0.0003), and delayed sternal closure (P=0.0033) increased transfusion risk. Transfusion was associated with prolonged mechanical ventilation (6 [interquartile range 4, 12] versus 3 [1, 5] days, P=0.02) and intensive care unit stay (19 [12, 33] versus 9 [6, 19] days, P=0.016). When stratified by number of transfusions (0, 1, or >1), duration of mechanical ventilation (3 [1, 5] versus 4 [3, 6] versus 9 [5, 16] days [P<0.0001]) and intensive care unit stay (9 [6, 19] versus 13 [8, 25] versus 21 [13, 38] days [P<0.0001]) increased for those transfused more than once. Most subjects who died were transfused, though the association with mortality was not significant. Conclusions Packed red blood cell transfusion after Stage 1 palliation is common, and transfusion practice is variable. Transfusion is a significant predictor of longer intensive care unit stay and mechanical ventilation. Further studies to define evidence-based transfusion thresholds are warranted.

Heart failure in single right ventricle congenital heart disease: physiological and molecular considerations

Because of remarkable surgical and medical advances over the past several decades, there are growing numbers of infants and children living with single ventricle congenital heart disease (SV), where there is only one functional cardiac pumping chamber. Nevertheless, cardiac dysfunction (and ultimately heart failure) is a common complication in the SV population, and pharmacological heart failure therapies have largely been ineffective in mitigating the need for heart transplantation. Given that there are several inherent risk factors for ventricular dysfunction in the setting of SV in addition to probable differences in molecular adaptations to heart failure between children and adults, it is perhaps not surprising that extrapolated adult heart failure medications have had limited benefit in children with SV heart failure. Further investigations into the molecular mechanisms involved in pediatric SV heart failure may assist with risk stratification as well as development of targeted, efficacious therapies specific to this patient population. In this review, we present a brief overview of SV anatomy and physiology, with a focus on patients with a single morphological right ventricle requiring staged surgical palliation. Additionally, we discuss outcomes in the current era, risk factors associated with the progression to heart failure, present state of knowledge regarding molecular alterations in end-stage SV heart failure, and current therapeutic interventions. Potential avenues for improving SV outcomes, including identification of biomarkers of heart failure progression, implications of personalized medicine and stem cell-derived therapies, and applications of novel models of SV disease, are proposed as future directions.

Uncorrected Univentricular Heart in an Adult

An 18-year-old male with an unknown medical history presented with palpitations and paroxysmal episodes of shortness of breath over a 7-year period. Transthoracic echocardiography displayed a univentricle with an ejection fraction of 45%. The patient refused treatment and was lost to follow-up.