Midterm ventricular performance after Norwood procedure with right ventricular-pulmonary artery conduit

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.

Impact of Initial Shunt Type on Echocardiographic Indices in Children After Single Right Ventricle Palliations

Background Heart size and function in children with single right ventricle (RV) anomalies may be influenced by shunt type at the Norwood procedure. We sought to identify shunt-related differences during early childhood after staged surgical palliations using echocardiography. Methods We compared echocardiographic indices of RV, neoaortic, and tricuspid valve size and function at 14 months, pre-Fontan, and 6 years in 241 subjects randomized to a Norwood procedure using either the modified Blalock-Taussig shunt or RV-to-pulmonary-artery shunt. Results At 6 years, the shunt groups did not differ significantly in any measure except for increased indexed neoaortic area in the modified Blalock-Taussig shunt. RV ejection fraction improved between pre-Fontan and 6 years in the RV-to-pulmonary artery shunt group but was stable in the modified Blalock-Taussig shunt group. For the entire cohort, RV diastolic and systolic size and functional indices were improved at 6 years compared with earlier measurements, and indexed tricuspid and neoaortic annular area decreased from 14 months to 6 years. The prevalence of ≥moderate tricuspid and neoaortic regurgitation was uncommon and did not vary by group or time period. Diminished RV ejection fraction at the 14-month study was predictive of late death/transplant; the hazard of late death/transplant when RV ejection fraction was <40% was tripled (hazard ratio, 3.18; 95% CI, 1.41-7.17). Conclusions By 6 years after staged palliation, shunt type has not impacted RV size and function, and RV and valvar size and function show beneficial remodeling. Poor RV systolic function at 14 months predicts worse late survival independent of the initial shunt type. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT00115934.

Comparison of cardiac energetics after transcatheter and surgical aortic valve replacements

OBJECTIVES

The effect of transcatheter aortic valve replacement (TAVR) on cardiac energetics has not been described. We compared changes in cardiac energetics after TAVR with those after surgical aortic valve replacement (SAVR).

METHODS

We retrospectively estimated end-systolic elastance (Ees) and effective arterial elastance (Ea) using blood pressure and left ventricular (LV) volume obtained from echocardiography. LV efficiency [ventriculoarterial coupling (Ea/Ees) and the stroke work to pressure-volume area ratio (SW/PVA)] was calculated. Measurements were taken before, 1 week after and 1 year after bioprosthetic aortic valve replacement (TAVR, n = 56; SAVR, n = 61) in patients with severe aortic stenosis and preserved ejection fraction.

RESULTS

Patients with TAVR had a lower aortic valve pressure gradient and larger stroke volume 1 week after the procedure than those with SAVR. Ea was more markedly decreased, and LV efficiency was significantly improved 1 week after TAVR (SW/PVA 68.1% ± 8.4% to 72.0% ± 8.5%, P < 0.001), but LV efficiency was unchanged 1 week after SAVR (SW/PVA 70.1% ± 7.4% to 69.1%  ±  8.0%). LV efficiency was improved 1 year after both procedures (SW/PVA 75.5% ± 6.1% in TAVR; 74.7% ± 6.4% in SAVR).

CONCLUSIONS

TAVR decreases the transvalvular pressure gradient further without deteriorating stroke volume in the early postoperative period, which is accompanied by early improvement in afterload and LV efficiency compared with SAVR. Improvement in LV efficiency at mid-term follow-up is satisfactory after both procedures.

Mathematical Analysis and Physical Profile of Blalock-Taussig Shunt and Sano Modification Procedure in Hypoplastic Left Heart Syndrome: Review of the Literature and Implications for the Anesthesiologist

The first stage of surgical treatment for hypoplastic left heart syndrome (HLHS) includes the creation of artificial systemic-to-pulmonary connections to provide pulmonary blood flow. The modified Blalock-Taussig (mBT) shunt has been the technique of choice for this procedure; however, a right ventricle-pulmonary artery (RV-PA) shunt has been introduced into clinical practice with encouraging but still conflicting outcomes when compared with the mBT shunt. The aim of this study is to explore mathematical modeling as a tool for describing physical profiles that could assist the surgical team in predicting complications related to stenosis and malfunction of grafts in an attempt to find correlations with clinical outcomes from clinical studies that compared both surgical techniques and to assist the anesthesiologist in making decisions to manage patients with this complex cardiac anatomy. Mathematical modeling to display the physical characteristics of the chosen surgical shunt is a valuable tool to predict flow patterns, shear stress, and rate distribution as well as energetic performance at the graft level and relative to ventricular efficiency. Such predictions will enable the surgical team to refine the technique so that hemodynamic complications be anticipated and prevented, and are also important for perioperative management by the anesthesia team.

Selective Use of the Blalock-Taussig Shunt and Right Ventricle-to-Pulmonary Artery Conduit During the Norwood Procedure

Background:

The single ventricle reconstruction trial showed better one-year transplant-free survival for the right ventricle-to-pulmonary artery (RV-to-PA) conduit over the modified Blalock-Taussig shunt (mBTS) at Norwood operation. However, concerns remain about the long-term effects of a neonatal ventriculotomy. In our institution, we have used specific selection criteria for the use of mBTS in the Norwood operation.

Methods:

We reviewed 122 consecutive neonates undergoing the Norwood procedure from December 2006 to December 2013. We used the following criteria to select our source of pulmonary blood flow: (1) presence of a dominant morphologic left ventricle; (2) presence of antegrade blood in an ascending aorta that is greater than 3 mm; and (3) presence of significant large “crossing coronaries” on ventricle. All patients who met any of the above 3 criteria underwent an mBTS while the remaining patients underwent an RV-to-PA conduit.

Results:

Seventy-five (61.5%) patients had the RV-to-PA conduit and 47 (38.5%) patients had an mBTS. The overall surgical mortality was 9%. Mean follow-up interval was 23.5 months. Actuarial transplant-free survival was similar at 12, 24, 36, and 48 months in both the mBTS group and the RV-to-PA conduit group. In the RV-to-PA conduit group, actuarial transplant-free survival was 73% at 12 months, 71% at 24 months, 71% at 36 months, and 67% at 48 months, while in the mBTS group, actuarial transplant-free survival was 82% at 12 months, 75% at 24 months, 75% at 36 months, and 75% at 48 months.

Conclusion:

Our selection criteria for mBTS have allowed us to obtain equivalent transplant-free survival at 12, 24, 36, and 48 months when compared to the RV-to-PA conduit group.

Factors affecting Fontan length of stay: Results from the Single Ventricle Reconstruction trial

BACKGROUND

In the Single Ventricle Reconstruction trial, infants with hypoplastic left heart syndrome (HLHS) who received a right-ventricle-to-pulmonary-artery shunt (RVPAS) versus a modified Blalock-Taussig shunt (MBTS) had lower early postoperative mortality, but more complications at 14 months. We explored the effect of shunt type and other patient, medical, and surgical factors on postoperative length of stay (LOS) after the Fontan operation.

METHODS

Fontan postoperative course was ascertained from medical record review. Cox proportional hazards modeling was used to identify factors associated with LOS.

RESULTS

Of 327 subjects who underwent Fontan, 323 were analyzed (1 death, 1 biventricular repair, 2 with missing data). Median age and weight at Fontan were 2.8 years (interquartile range [IQR]: 2.3, 3.4) and 12.7 kg (IQR: 11.4, 14.1), respectively. Fontan type was extracardiac in 55% and lateral tunnel in 45%; 87% were fenestrated. The RVPAS and MBTS subjects had similar LOS (median 11 days [IQR: 9, 18] vs 10 days [IQR: 9, 13]; P = .23). Independent risk factors for longer LOS were treatment center (P < .01), LOS at stage II (hazard ratio [HR] 1.02 for each additional day; P < .01), and pre-Fontan complications (HR 1.03 for each additional complication; P = .04). Use of deep hypothermic circulatory arrest at Fontan (HR 0.64; P = .02) was independently associated with shorter LOS. When center was excluded from the model, pre-Fontan complications and use of circulatory arrest were no longer significant; instead, older age at stage II (HR 1.08 for each additional month; P = .01) predicted longer LOS. In 254 subjects who had a pre-Fontan echocardiogram, at least moderate tricuspid regurgitation was independently associated with longer LOS, both with center (HR 1.72; P < .01) and without center in the model (HR 1.49; P = .02).

CONCLUSIONS

In this multicenter prospective cohort of subjects with HLHS, Norwood shunt type was not associated with Fontan LOS. Rather, global measures of earlier medical complexity indicate greater likelihood of longer LOS after the Fontan operation.

Long-term progression and survival following Norwood Single Ventricle Reconstruction

PURPOSE OF REVIEW

Much data exist concerning Norwood discharge mortality. Less is known about late survival. Examining the available data in light of the Single Ventricle Reconstruction trial is insightful as focus shifts toward long-term survival.

RECENT FINDINGS

Data from 2000 to 2001 demonstrated approximately 40-50% 10-year survival, 30-40% or less between 10 and 15 years. The shape of the curves was characteristic; the majority of deaths within the first year, followed by a late constant phase. Publications from 2001 to 2005 suggested that various combinations of technical and perioperative modifications allowed hospital discharge survivals as high as 90-94%. As results matured (2005-2010) a consistent message was that, although the shape of the newer curves was similar (highest hazard in the first 1 year), higher hospital survival shifted the later phase to yield better long-term survival (70-85% between 5 and 10 years). Some emphasized right ventricle-based shunts as a 'cause' of improving results. Since 2010, the Single Ventricle Reconstruction trial has matured and has increasingly shifted opinion away from the right ventricle shunt as a 'cause' of improved results. The survival of the right ventricle shunt group is slightly higher at 3 years, but the 1-year statistical significance has been lost and the two groups converge. As the Single Ventricle Reconstruction study was based on the interaction between randomized shunt and survival, the secondary and other endpoint analyses must be cautiously considered.

SUMMARY

The current English-language literature suggests a 60-80% 5-10 year survival expectation. The shape of the survival curve remains; the highest hazard remains the first year before a later, stable phase is reached. Rather than a 'magic bullet' theory surrounding one technique or practice, centers have differentially adopted various combinations to optimize Norwood survival. Optimizing interstage I survival is a challenge to further increase the percentage of patients reaching the late, stable phase.

Periscope modification of right ventricle-to-pulmonary artery shunt in Norwood operation

Given the purported hemodynamic advantages of the right ventricle (RV) to pulmonary artery (PA) conduit, many surgeons have adopted it as their preferred source of pulmonary blood flow during stage I palliation for hypoplastic left heart syndrome. Potential disadvantages of the RV-PA shunt include ventricular dysfunction, pseudoaneurysm formation, arrhythmia, and conduit obstruction, which can lead to a higher rate of unplanned reinterventions. The "dunk" technique was described to reduce the RV incision and proximal conduit obstruction; however, insertion of the ringed graft from the epicardium can be cumbersome and risk RV injury. We introduce a simplified, alternative method of placing the conduit, which we call the periscope technique, whereby the graft is withdrawn from within the RV cavity.

Impact of initial shunt type on cardiac size and function in children with single right ventricle anomalies before the Fontan procedure: the single ventricle reconstruction extension trial

BACKGROUND

In children with single right ventricular (RV) anomalies, changes in RV size and function may be influenced by shunt type chosen at the time of the Norwood procedure.

OBJECTIVES

The study sought to identify shunt-related differences in echocardiographic findings at 14 months and ≤6 months pre-Fontan in survivors of the Norwood procedure.

METHODS

We compared 2-dimensional and Doppler echocardiographic indices of RV size and function, neo-aortic and tricuspid valve annulus dimensions and function, and aortic size and patency at 14.1 ± 1.2 months and 33.6 ± 9.6 months in subjects randomized to a Norwood procedure using either the modified Blalock-Taussig shunt (MBTS) or right ventricle to pulmonary artery shunt (RVPAS).

RESULTS

Acceptable echocardiograms were available at both time points in 240 subjects (114 MBTS, 126 RVPAS). At 14 months, all indices were similar between shunt groups. From the 14-month to pre-Fontan echocardiogram, the MBTS group had stable indexed RV volumes and ejection fraction, while the RVPAS group had increased RV end-systolic volume (p = 0.004) and decreased right ventricular ejection fraction (RVEF) (p = 0.004). From 14 months to pre-Fontan, the treatment groups were similar with respect to decline in indexed neo-aortic valve area, >mild neo-aortic valve regurgitation (<5% at each time), indexed tricuspid valve area, and ≥moderate tricuspid valve regurgitation (<20% at each time).

CONCLUSIONS

Initial Norwood shunt type influences pre-Fontan RV remodeling during the second and third years of life in survivors with single RV anomalies, with greater RVEF deterioration after RVPAS. Encouragingly, other indices of RV function remain stable before Fontan regardless of shunt type. (Comparison of Two Types of Shunts in Infants with Single Ventricle Defect Undergoing Staged Reconstruction-Pediatric Heart Network; NCT00115934).

Shunt choice in single right ventricle patients: an update

Hypoplastic left heart syndrome, the most common complex congenital heart malformation, is characterized by underdeveloped left-sided heart structures. The Norwood procedure followed by two-staged operations has permitted the extended survival of many of these patients. Survival, however, remains suboptimal with most of the morbidity and mortality occurring during the Norwood procedure hospitalization. The modified Blalock-Taussig shunt has been implicated in contributing to the mortality risk due to decreased systemic diastolic blood pressure and coronary perfusion. Therefore, the right ventricle-to-pulmonary artery shunt was recently reevaluated as a lower-risk source of pulmonary blood flow in the Norwood procedure. The Pediatric Heart Network Single Ventricle Reconstruction trial, sponsored by the NIH National Heart, Lung and Blood Institute, evaluated the two types of shunts during the Norwood procedure. This randomized clinical trial has yielded important insight into the effects of shunt selection on morbidity, mortality, hemodynamics and overall current outcomes for hypoplastic left heart syndrome.

Cardiac energetics analysis after aortic valve replacement with 16-mm ATS mechanical valve

The 16-mm ATS mechanical valve is one of the smallest prosthetic valves used for aortic valve replacement (AVR) in patients with a very small aortic annulus, and its clinical outcomes are reportedly satisfactory. Here, we analyzed the left ventricular (LV) performance after AVR with the 16-mm ATS mechanical valve, based on the concept of cardiac energetics analysis. Eleven patients who underwent AVR with the 16-mm ATS mechanical valve were enrolled in this study. All underwent echocardiographic examination at three time points: before AVR, approximately 1 month after AVR, and approximately 1 year after AVR. LV contractility (end-systolic elastance [Ees]), afterload (effective arterial elastance [Ea]), and efficiency (ventriculoarterial coupling [Ea/Ees] and the stroke work to pressure-volume area ratio [SW/PVA]) were noninvasively measured by echocardiographic data and blood pressure measurement. Ees transiently decreased after AVR and then recovered to the pre-AVR level at the one-year follow-up. Ea significantly decreased in a stepwise manner. Consequently, Ea/Ees and SW/PVA were also significantly improved at the one-year follow-up compared with those before AVR. The midterm LV performance after AVR with the 16-mm ATS mechanical valve was satisfactory. AVR with the 16-mm ATS mechanical valve is validated as an effective treatment for patients with a very small aortic annulus. The cardiac energetics variables, coupling with the conventional hemodynamic variables, can contribute to a better understanding of the patients' clinical conditions, and those may serve as promising indices of the cardiac function.

Impact of pre-stage II hemodynamics and pulmonary artery anatomy on 12-month outcomes in the Pediatric Heart Network Single Ventricle Reconstruction trial

OBJECTIVE

To compare the interstage cardiac catheterization hemodynamic and angiographic findings between shunt types for the Pediatric Heart Network Single Ventricle Reconstruction trial. The trial, which randomized subjects to a modified Blalock-Taussig shunt (MBTS) or right ventricle-to-pulmonary artery shunt (RVPAS) for the Norwood procedure, demonstrated the RVPAS was associated with a smaller pulmonary artery diameter but superior 12-month transplant-free survival.

METHODS

We analyzed the pre-stage II catheterization data for the trial subjects. The hemodynamic variables and shunt and pulmonary angiographic data were compared between shunt types; their association with 12-month transplant-free survival was also evaluated.

RESULTS

Of 549 randomized subjects, 389 underwent pre-stage II catheterization. A smaller size, lower aortic and superior vena cava saturation, and higher ventricular end-diastolic pressure were associated with worse 12-month transplant-free survival. The MBTS group had a lower coronary perfusion pressure (27 vs 32 mm Hg; P<.001) and greater pulmonary blood flow/systemic blood flow ratio (1.1 vs 1.0, P=.009). A greater pulmonary blood flow/systemic blood flow ratio increased the risk of death or transplantation only in the RVPAS group (P=.01). The MBTS group had fewer shunt (14% vs 28%, P=.004) and severe left pulmonary artery (0.7% vs 9.2%, P=.003) stenoses, larger mid-main branch pulmonary artery diameters, and greater Nakata indexes (164 vs 134, P<.001).

CONCLUSIONS

Compared with the RVPAS subjects, the MBTS subjects had more hemodynamic abnormalities related to shunt physiology, and the RVPAS subjects had more shunt or pulmonary obstruction of a severe degree and inferior pulmonary artery growth at pre-stage II catheterization. A lower body surface area, greater ventricular end-diastolic pressure, and lower superior vena cava saturation were associated with worse 12-month transplant-free survival.

Left ventricular efficiency after ligation of patent ductus arteriosus for premature infants

OBJECTIVE

The purpose of this study was to evaluate the hemodynamic changes in left ventricular function before and after patent ductus arteriosus ligation in premature infants with regard to the energetic efficiency of left ventricular pumping.

METHODS

Thirty-five premature infants who underwent patent ductus arteriosus ligation were enrolled in this study. Left ventricular efficiency was evaluated at 4 points: within 24 hours before patent ductus arteriosus ligation, within 24 hours after patent ductus arteriosus ligation, between postoperative days 2 and 4, and on postoperative day 7. The indices of contractility (end-systolic elastance) and afterload (effective arterial elastance) were approximated on the basis of the systemic blood pressure and systolic or diastolic left ventricular volume. The ratio of stroke work and pressure-volume area, representing the ventricular efficiency, was estimated using the following theoretic formula: the ratio of stroke work and pressure-volume area = 1/(1 + 0.5 ventriculoarterial coupling).

RESULTS

Left ventricular efficiency was transiently deteriorated within 24 hours after patent ductus arteriosus ligation because of the marked increase of the afterload and the slight increase of contraction, and then recovered to preoperation levels by 2 to 4 days after patent ductus arteriosus ligation.

CONCLUSIONS

Analysis of indices representing the afterload, contractility, and energetic efficiency of the left ventricle may provide practical information for the management of premature infants during the postoperative period after patent ductus arteriosus ligation.

Early mitral valve surgery for chronic severe mitral regurgitation optimizes left ventricular performance and left ventricular mass regression

OBJECTIVE

The optimal timing of mitral valve surgery for severe mitral regurgitation is controversial. We aimed to evaluate the changes in left ventricular performance using ventricular energetics and left ventricular mass regression after the surgery to determine the appropriate surgical timing in asymptomatic patients with severe mitral regurgitation.

METHODS

Fifty consecutive asymptomatic or minimally symptomatic patients who electively underwent the surgery for severe mitral regurgitation were studied retrospectively. Contractility (end-systolic elastance), afterload (effective arterial elastance), and efficiency (ventriculoarterial coupling and ratio of stroke work to pressure-volume area), and left ventricular mass index were measured echocardiographically before and 1 month after surgery. Two-way repeated-measures analysis of variance was used to compare the parameters between patients with (n = 17) and without (n = 33) left ventricular dysfunction (ie, ejection fraction ≤60% and/or end-systolic dimension ≥40 mm).

RESULTS

Contractility did not change significantly (P = .94) but the afterload increased significantly (P < .0001) in both groups. Consequently, the efficiency deteriorated significantly (ventriculoarterial coupling, P = .0004; ratio of stroke work to pressure-volume area, P < .0001). Furthermore, the left ventricular mass index improved remarkably in both groups (P < .0001). Alternatively, the patients with normal left ventricular function had greater contractility (P < .0001), less worsened efficiency (P < .0001 and P < .0001, respectively), and a better left ventricular mass index (P = .0002) after surgery.

CONCLUSIONS

Early surgery for severe mitral regurgitation preserves left ventricular performance and improves left ventricular mass regression in asymptomatic patients with normal ventricular function.

Can Randomized Clinical Trials Impact the Surgical Approach for Hypoplastic Left Heart Syndrome?

The Eighth International Conference of the Pediatric Cardiac Intensive Care Society was held in Miami, Florida, December 8 to 11, 2010. The program included a session dedicated to the management of hypoplastic left heart syndrome (HLHS), with particular emphasis on the innovations that have led to contemporary schemes of management and the role of clinical trials in the evolution and acceptance of these strategies. An invited panel of experts reviewed the historical evolution of staged surgical reconstruction, the randomized clinical trials that have been undertaken thus far, and the extent to which these have, or have not, influenced individual and institutional approaches to management of HLHS.

Impact of staged palliation on somatic growth in patients with hypoplastic left heart syndrome

BACKGROUND

Somatic growth pattern in infants undergoing staged palliation for hypoplastic left heart syndrome (Norwood procedure [NP], stage 2 palliation [S2P], and Fontan procedure [FP]) during transition toward a more energy efficient series circulation is not well understood.

OBJECTIVES

We sought to determine growth pattern in these infants and factors influencing it.

METHODS

Patients who underwent NP since 2001 and survived at least 1 year after S2P were followed until FP or death/heart transplantation (n = 46). Weight for age z-scores (WAZ) were measured prior to NP; at initial discharge; prior to S2P; at four time periods after S2P; and prior to FP. Impact of gender, race, era of NP, anatomic subtype, NP shunt type, gastrostomy, home-surveillance program (daily weights and pulse oximetry), and interstage oxygen saturation on WAZ was evaluated.

RESULTS

Repeated measures anova showed a significant change in WAZ across time periods (P < 0.0005), with a significant decline from Pre-NP to Pre-S2P (P < 0.0005) and steady increase from Pre-S2P to Pre-FP (P= 0.016). None of the factors evaluated had a significant effect on this growth pattern. Length of hospital stay after NP was negatively correlated with WAZ at discharge (P= 0.001), but not for other time periods. Intervals from discharge to S2P and NP to S2P interval did not correlate with WAZ.

CONCLUSION

Somatic growth is significantly impaired after NP but recovers steadily following S2P, as the patient transitions toward separated series circulation. Earlier S2P may lead to earlier resumption of normal growth in this critical period of early infancy.

Modified Norwood procedure with a handmade down-sizing valved right ventricle-to-pulmonary artery conduit

First-stage palliation of hypoplastic left heart syndrome has been revolutionized by the recent introduction of a right ventricle-to-pulmonary artery (RV-PA) conduit as an alternative to a systemic-to-pulmonary shunt. However, most conduits are unvalved, and the use of valved xenografts was abandoned during the early era of this operation. We performed a successful modified Norwood operation in a 2-month-old infant with aortic atresia and ventricular and atrial septal defects using a hand-made down-sizing valved graft as an RV-PA conduit. The postoperative course was uneventful with well-balanced pulmonary and arterial perfusion. We believe that minimization of the regurgitant volume from an unvalved prosthetic conduit by utilizing this modification might be of benefit in this particular group of patients.

Comparison of shunt types in the Norwood procedure for single-ventricle lesions

BACKGROUND

The Norwood procedure with a modified Blalock-Taussig (MBT) shunt, the first palliative stage for single-ventricle lesions with systemic outflow obstruction, is associated with high mortality. The right ventricle-pulmonary artery (RVPA) shunt may improve coronary flow but requires a ventriculotomy. We compared the two shunts in infants with hypoplastic heart syndrome or related anomalies.

METHODS

Infants undergoing the Norwood procedure were randomly assigned to the MBT shunt (275 infants) or the RVPA shunt (274 infants) at 15 North American centers. The primary outcome was death or cardiac transplantation 12 months after randomization. Secondary outcomes included unintended cardiovascular interventions and right ventricular size and function at 14 months and transplantation-free survival until the last subject reached 14 months of age.

RESULTS

Transplantation-free survival 12 months after randomization was higher with the RVPA shunt than with the MBT shunt (74% vs. 64%, P=0.01). However, the RVPA shunt group had more unintended interventions (P=0.003) and complications (P=0.002). Right ventricular size and function at the age of 14 months and the rate of nonfatal serious adverse events at the age of 12 months were similar in the two groups. Data collected over a mean (+/-SD) follow-up period of 32+/-11 months showed a nonsignificant difference in transplantation-free survival between the two groups (P=0.06). On nonproportional-hazards analysis, the size of the treatment effect differed before and after 12 months (P=0.02).

CONCLUSIONS

In children undergoing the Norwood procedure, transplantation-free survival at 12 months was better with the RVPA shunt than with the MBT shunt. After 12 months, available data showed no significant difference in transplantation-free survival between the two groups. (ClinicalTrials.gov number, NCT00115934.)

In hypoplastic left heart patients is Sano shunt compared with modified Blalock-Taussig shunt associated with deleterious effects on ventricular performance?

A best evidence topic in congenital cardiac surgery was written according to a structured protocol. The question addressed was: in hypoplastic left heart patients is Sano shunt compared with modified Blalock-Taussig (mBT) shunt associated with deleterious effects on ventricular performance? Sano shunt modification of Norwood procedure involves construction of a right ventricle to pulmonary artery (RV-PA) conduit as an alternative source of pulmonary blood flow. Compared with the mBT shunt, the RV-PA conduit provides a more stable haemodynamic state in the immediate postoperative period and is reported to be associated with lower interstage mortality. However, concerns regarding the impact of ventriculotomy on short- and long-term performance of single ventricle have been expressed. Altogether 101 papers were found using the reported search terms, from which seven represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. None of the echocardiographic or clinical outcome studies showed poor ventricular performance after ventriculotomy of the systemic RV for construction of Sano shunt. A small autopsy study of 11 patients showed greater remodelling of the ventricular myocardial extracellular matrix in patients with RV-PA conduit with potential implications for poor ventricular performance. We conclude that the current available evidence, although weak, does not show any adverse effects of ventriculotomy on ventricular performance in patients with Sano shunt in the short- and medium-term. However, all the existing studies are limited by small numbers, non-randomised design and retrospective nature with failure of correlation of echocardiographic indices to clinical outcomes. It is expected that the Pediatric Heart Network randomised controlled trial will address this important issue.

Hypoplastic left heart syndrome

Hypoplastic left heart syndrome is a rare congenital heart defect in which the left side of the heart is underdeveloped. Surgical management of hypoplastic left heart syndrome has changed the prognosis of the condition that was previously regarded as fatal. We discuss surgical strategies based on staged procedures, with the right ventricle supporting both systemic and pulmonary circulation. We also discuss other management options, such as neonatal transplantation and the recent innovation of hybrid techniques. Surgical techniques and the understanding of the pathophysiology of this condition have been at the forefront of neonatal cardiac surgery and intensive care. The management of the syndrome remains a challenge because affected children grow into adolescence and adulthood posing various new problems and demands.

Histological study of right ventricle-pulmonary artery valved conduit implantation (RPVC) in dogs with pulmonic stenosis

We examined whether right ventricle-pulmonary artery valved conduit (RPVC) implantation can overcome the disadvantages of current procedures for pulmonic stenosis (PS). We histologically evaluated the feasibility of RPVC using a homograft in PS model dogs. Eight dogs underwent pulmonary artery banding (PAB) and then 12 weeks later were assigned to PAB (n=4) or PAB+RPVC (n=4) groups. Dogs in the PAB group received no treatment throughout the experimental period, whereas the PAB+RPVC group underwent RPVC. At 1 year after PAB, hearts and conduits were explanted from euthanized dogs and histologically evaluated. The ratios (%) of myocardial fibrosis on right ventricle (RV) epicardial, median and endocardial layers were significantly lower in the PAB+RPVC, than in the PAB group. The ratio of myocardial fibrosis on left ventricular (LV) epicardial and endocardial layers were significantly lower in the PAB+RPVC, than in the PAB group. Neo-intimal thickness in the anastomosis areas of the Denacol and PAB+RPVC groups was 42.77 +/- 30.19 and 88.30 +/- 27.24 microm, respectively, with no significant differences between the groups. Calcification and neo- intima hypertrophy were not obvious in the valve area. Immunohistological staining showed that the internal surface of the anastomosis and intermediate areas were positive for endothelial cells. We concluded that RPVC using a bioprosthetic graft can apparently overcome the disadvantages of current procedures for pulmonic stenosis.

Ventricular energetics in aortic root replacement for annuloaortic ectasia with aortic regurgitation

Aortic root replacement (Bentall operation) is the standard operation for patients who have lesions of the ascending aorta associated with aortic valve disease. We analyzed the mid-term results for left ventricular energetics after the Bentall operation for annuloaortic ectasia with aortic regurgitation. We measured left ventricular contractility (end-systolic elastance; Ees), afterload (effective arterial elastance; Ea), and efficiency (ventriculoarterial coupling; Ea/Ees, and the ratio of stroke work and pressure-volume area; SW/PVA) based on transthoracic echocardiography data before, after, and approximately 1 year after the Bentall operation in 15 patients with annuloaortic ectasia with aortic regurgitation. Left ventricular volume was calculated by the Teichholz M-mode method. Ees and Ea were approximated as follows: Ees=mean blood pressure/minimal left ventricular volume, and Ea=systolic blood pressure/(maximal left ventricular volume--minimal left ventricular volume). Ea/Ees and SW/PVA were then calculated. Left ventricular volume was normalized with body surface area. Ees increased after the Bentall operation and around 1 year later (from 2.17+/-1.09 to 3.92+/-2.26 and 5.33+/-1.90 mmHg x m(2)/ml, P<0.001), thus resulting in an improvement in SW/PVA (from 68.8+/-8.2 to 70.9+/-9.5 and 74.7+/-5.2%, P=0.045). Ea also increased after the Bentall operation and 1 year later (from 1.77+/-0.61 to 2.88+/-1.28 and 3.54+/-1.43 mmHg x m(2)/ml, P<0.001). The mid-term results for ventricular contractility and efficiency after the Bentall operation for annuloaortic ectasia with aortic regurgitation are excellent and satisfactory.

Pathological changes and myocardial remodelling related to the mode of shunting following surgical palliation for hypoplastic left heart syndrome

BACKGROUND

The modification of placing the shunt from the right ventricle to the pulmonary arteries, also known as Sano procedure, has allegedly improved results over the short term in surgical palliation of hypoplastic left heart syndrome with the Norwood procedure. With this in mind, we reviewed autopsied specimens from neonates and children who did not survive after either a classic arterio-pulmonary shunt, or the modified procedure with the shunt placed from the right ventricle to the pulmonary arteries, so as to evaluate the pathological substrates of the remodelling of the systemic right ventricle, assessing any differences induced by the 2 techniques.

METHODS

We obtained the hearts from 11 patients with neonatal diagnosis of hypoplastic left heart syndrome who died after the first or second stages of the Norwood sequence of operations, comparing them with 6 normal hearts matched for age and weight. Macroscopic, microscopic and morphometric analysis were performed on each specimen, evaluating the diameter of the myocytes, extracellular matrix remodelling in terms of fibrosis and type of collagen, and vascularization in terms of capillary density.

RESULTS

Hypertrophy of the myocytes was significantly increased in the hearts from patients having either a classic arterio-pulmonary or the ventriculo-pulmonary modification of the shunt compared to controls (p < 0.05). Myocardial fibrosis was increased in those having a shunt placed from the right ventricle to the pulmonary arteries when compared to the other 2 groups. The ratio of collagen I to collagen III was similar in those undergoing a classic arterio-pulmonary shunt compared to controls (0.94), but was lower in those having a shunt placed from the right ventricle to the pulmonary arteries (0.61), with an increase in collagen type III. The density of capillaries was lower in those who had undergone a classic arterial shunt when compared to the others.

CONCLUSION

We have shown greater remodelling of the ventricular myocardial extracellular matrix in patients having a shunt from the right ventricle to the pulmonary arteries when compared to those having a classic arterio-pulmonary shunt, with this remodelling progressing even after the neonatal period. This may influence a later suboptimal ventricular performance.

Stage I palliation for hypoplastic left heart syndrome: Is a right ventricle to pulmonary artery conduit associated with improved outcomes? Critical appraisal of Cua et al: Early postoperative outcomes in a series of infants with hypoplastic left heart syndrome undergoing stage I palliation operation with either modified Blalock-Taussig shunt or right ventricle to pulmonary artery conduit (Pediatr Crit Care Med 2006; 7:238-244)

OBJECTIVE

To review the findings and discuss the implications of studies comparing Norwood procedure with either modified Blalock-Taussig shunt (NW-BT) or right ventricle to pulmonary artery conduit (NW-RVPA) in stage I palliation of hypoplastic left heart syndrome (HLHS).

DESIGN

A critical appraisal of "Early postoperative outcomes in a series of infants with hypoplastic left heart syndrome undergoing stage I palliation operation with either modified Blalock-Taussig shunt or right ventricle to pulmonary artery conduit" by Cua et al. (Pediatr Crit Care Med 2006; 7:238-244) with literature review.

FINDINGS

Several retrospective studies using historical controls have reported improved results with NW-RVPA compared with NW-BT for stage I palliation of HLHS. The study by Cua et al. is one of a few recent articles with concurrent series that have found no difference in early postoperative mortality or morbidity, although in comparison with the NW-BT group, the NW-RVPA group had significantly shorter duration of mechanical ventilation, decreased length of intensive care unit stay and hospital stay, and shorter time to sternal closure and to establishment of enteral feeds.

CONCLUSIONS

NW-RVPA has theoretical advantages over NW-BT and is associated with excellent outcome results. However, available data are insufficient to prove benefit in terms of mortality or morbidity. A multicenter randomized trial is currently being conducted, which should provide more conclusive information.

Design and rationale of a randomized trial comparing the Blalock-Taussig and right ventricle-pulmonary artery shunts in the Norwood procedure

OBJECTIVE

The initial palliative procedure for patients born with hypoplastic left heart syndrome and related single right ventricle anomalies, the Norwood procedure, remains among the highest risk procedures in congenital heart surgery. The classic Norwood procedure provides pulmonary blood flow with a modified Blalock-Taussig shunt. Improved outcomes have been reported in a few small, nonrandomized studies of a modification of the Norwood procedure that uses a right ventricle-pulmonary artery shunt to provide pulmonary blood flow. Other nonrandomized studies have shown no differences between the two techniques.

METHODS

The Pediatric Heart Network designed a randomized clinical trial to compare outcomes for subjects undergoing a Norwood procedure with either the right ventricle-pulmonary artery or modified Blalock-Taussig shunt. Infants with a diagnosis of single, morphologically right ventricle anomaly who are undergoing a Norwood procedure are eligible for inclusion in this study. The primary outcome is death or cardiac transplant 12 months after random assignment. Secondary outcomes include postoperative morbidity after Norwood and stage II palliation procedures, right ventricular function and pulmonary arterial growth at stage II palliation, and neurodevelopmental outcomes at 14 months old. Incidence of adverse events will also be compared between treatment groups.

CONCLUSION

This study will make an important contribution to the care of patients with hypoplastic left heart syndrome and related forms of single, morphologically right ventricle. It also establishes a model with which other operative interventions for patients with congenital cardiovascular malformations can be evaluated in the future.

Impact of placing a conduit from the right ventricle to the pulmonary arteries as the first stage of further palliation in the Norwood sequence for hypoplasia of the left heart

OBJECTIVE

We describe the experience from a single institution with the Norwood sequence of palliation for hypoplasia of the left heart, emphasizing complications related to placement of a conduit from the right ventricle to the pulmonary arteries and their management.

METHODS

Between November, 2002 and January, 2006, we palliated 32 patients with hypoplastic left heart syndrome or its variants by placing a conduit from the right ventricle to the pulmonary arteries. We reviewed retrospectively the charts and angiograms from these patients.

RESULTS

Hospital survival after construction of the conduit was 90.6%. There were 3 interstage deaths, of which 2 were likely due severe obstruction of the conduit. Stents were implanted into the proximal or medial portions of the conduits of 3 patients. Early revision of the distal anastomosis, and shortening the conduit, was performed early postoperatively in 2 patients. So far, 24 out 26 survivors of the first stage underwent a bi-directional cavopulmonary anastomosis after a mean interval of 4.3 plus or minus 1.4 months. Of these, 3 required a semi-urgent second stage of palliation because of worsening cyanosis, with one patient dying after the second stage. Completion of the Fontan circulation by insertion of an extracardiac conduit was performed in 8 patients at the mean age of 19.8 plus or minus 2.2 months. We were able to achieve biventricular repair in 1 patient, with aortic atresia, hypoplastic arch and ventricular septal defect, 4.3 months after the initial palliative procedure. Overall survival of the whole cohort of 32 patients was 78.9%, plus or minus 7.8%, at 5 months, and 74.3%, plus or minus 8.6%, up to 25 months.

CONCLUSIONS

The introduction of the conduit placed from the right ventricle to the pulmonary arteries has led to an improved outcome in the complex entity of hypoplastic left heart syndrome and its variants. Stenosis of the conduit, nonetheless, may account for significant interstage morbidity, and often requires intervention or early installation of the second stage of palliation.

A contemporary comparison of the effect of shunt type in hypoplastic left heart syndrome on the hemodynamics and outcome at stage 2 reconstruction

OBJECTIVE

We compare the hemodynamics and perioperative course of shunt type in hypoplastic left heart syndrome at the time of stage 2 reconstruction and longer-term survival.

METHODS

We retrospectively reviewed the echocardiograms, catheterizations, and hospital records of all patients who had a stage 1 reconstruction between January 2002 and May 2005 and performed a cross-sectional analysis of hospital survivors.

RESULTS

One hundred seventy-six patients with hypoplastic left heart syndrome and variants underwent a stage 1 reconstruction with either a right ventricle-pulmonary artery conduit (n = 62) or a modified Blalock-Taussig shunt (n = 114). The median duration of follow-up is 29.1 months (range, 0-57 months). By means of Kaplan-Meier analysis, there is no difference in survival at 3 years (right ventricle-pulmonary artery conduit: 73% [95% confidence limit, 59%-83%] vs modified Blalock-Taussig shunt: 69% [95% confidence limit, 59%-77%]; P = .6). One hundred twenty-four patients have undergone stage 2 reconstruction (78 modified Blalock-Taussig shunts and 46 right ventricle-pulmonary artery conduits). At the time of the stage 2 reconstruction, patients with right ventricle-pulmonary artery conduits were younger (153 days [range, 108-340 days]; modified Blalock-Taussig shunt, 176 days [range, 80-318 days]; P = .03), had lower systemic oxygen saturation (73% [range, 58%-85%] vs 77% [range, 57%-89%], P < .01), and had higher preoperative hemoglobin levels (15.8 g/dL [range, 13-21 g/dL] vs 14.8 g/dL [range, 12-19 g/dL], P < .01) compared with those of the modified Blalock-Taussig shunt group. By means of echocardiographic evaluation, there was a higher incidence of qualitative ventricular dysfunction in patients with right ventricle-pulmonary artery conduits (14/46 [31%] vs 9/73 [12%], P = .02). However, no difference was observed in common atrial pressure or the arteriovenous oxygen difference.

CONCLUSION

Interim analyses suggest no advantage of one shunt type over another. This report raises concern of late ventricular dysfunction and outcome in patients with a right ventricle-pulmonary artery conduit.

Stage I palliation for hypoplastic left heart syndrome: Norwood versus Sano modification

PURPOSE OF REVIEW

Advancements in surgical technique and perioperative care have significantly improved the survival of infants born with hypoplastic left heart syndrome. A recent modification to the Norwood procedure is being adopted by many centers to improve postoperative hemodynamic stability and survival to stage II palliation. The late effects of this modification, however, are speculated and have not been investigated.

RECENT FINDINGS

Center-specific improved short-term outcomes have been reported in a few small, nonrandomized studies of a new approach to the Norwood procedure, which utilizes a right ventricle to pulmonary artery shunt or Sano modification to provide pulmonary blood flow rather than the standard modified Blalock-Taussig shunt.

SUMMARY

The classic Norwood procedure and Sano modification each have specific advantages and disadvantages in both the short and long term. Data comparing the two techniques are nonrandomized, contradictory, and utilize historical controls. The optimal shunt to improve survival to the second-stage palliation is unknown. A multicenter randomized clinical trial comparing the Sano with the modified Blalock-Taussig shunt in hypoplastic left heart syndrome or variants is currently in progress and should hopefully provide future guidelines for shunt selection based on clinical presentation.

The modified Blalock-Taussig shunt versus the right ventricle-to-pulmonary artery conduit for the Norwood procedure

The initial Norwood procedure remains the highest risk operation for the staged repair of univentricular congenital malformations with associated systemic outflow obstruction. The modified Blalock-Taussig shunt (MBTS) has been implicated as a major cause of not only the operative mortality, but also associated morbidity and interstage attrition. The etiology of these events has often been attributed to the diastolic runoff and "coronary steal" associated with the MBTS, in addition to the delicate balance between systemic and pulmonary blood flow that characterizes all systemic-to-pulmonary artery shunts. Recently, there has been renewed interest in the right ventricle-to-pulmonary artery conduit as a source of pulmonary blood flow for the Norwood procedure as a potential method for minimizing the negative aspects of the MBTS. The current literature is contradictory, retrospective, and predominantly historically controlled. The Trial of Right Ventricular vs Modified Blalock-Taussig Shunt in Infants with Single Ventricle Defect Undergoing Staged Reconstruction, a randomized controlled clinical trial comparing the two techniques, is ongoing and may provide answers to this controversy.

Outcomes after the stage I reconstruction comparing the right ventricular to pulmonary artery conduit with the modified Blalock Taussig shunt

BACKGROUND

Recent reports advocate that a right ventricular to pulmonary artery (RV-PA) conduit improves outcome after the stage I reconstruction.

METHODS

We retrospectively compared the outcomes of all neonates who underwent a stage I reconstruction between January 1, 2002, and October 1, 2004, with use of the RV-PA conduit and modified Blalock-Taussig shunt (mBTS) interspersed over this time period.

RESULTS

In all, 149 infants underwent a stage I reconstruction (95 mBTS, 54 RV-PA) for hypoplastic left heart syndrome (HLHS) or variants. There was a preference for the RV-PA conduit in patients with aortic atresia (mBTS 30% versus RV-PA 67%, p < 0.01). There was no difference in surgical mortality (mBTS 14% versus RV-PA 17%, p = 0.67), time to extubation (mBTS 4.5 +/- 4.8 days versus RV-PA 3.9 +/- 3.5 days, p = 0.47), or length of hospital stay (mBTS 25 +/- 29 days versus RV-PA 21 +/- 23 days, p = 0.52). There was an increased incidence of shunt reinterventions in the patients with the RV-PA conduit (mBTS 17% versus RV-PA 32%, p = 0.04). Patients with RV-PA conduit returned earlier for stage II reconstruction (mBTS 6.5 +/- 2.5 months versus RV-PA 5.6 +/- 1.7 months, p = 0.05). There was no difference in overall mortality (mBTS 32% versus RV-PA 30%, p = 0.45) with a median duration of follow-up of 18 +/- 8 months.

CONCLUSIONS

Comparing shunt strategies (mBTS versus RV-PA) over the same time period, we found no difference in outcome. These data support the need for a larger prospective, randomized trial.

Homograft valved right ventricle to pulmonary artery conduit as a modification of the Norwood procedure

BACKGROUND

The use of a right ventricle to pulmonary artery (RV-PA) conduit in the Norwood procedure has been proposed to increase postoperative hemodynamic stability. A valve within the conduit should further decrease RV volume load. We report our clinical experience with this modification.

METHODS AND RESULTS

From February 2002 through August 2005, we performed 88 consecutive Norwood procedures using RV-PA conduits. We used composite valved conduits made from cryopreserved homograft and polytetrafluoroethylene (PTFE) in 66 cases (54 pulmonary, 12 aortic homografts), other valved conduits in 14, and unvalved PTFE in 8 cases. Hospital survival was 88.6% overall and increased to 93.1% after the initial year. Early interventions were required in 18 patients (16 for cyanosis). Prestage II cardiac catheterization was performed at a mean age of 126 days. Mean Qp/Qs was 1, with mean aortic saturation 71%, mean O2 extraction 24%, and mean right ventricular end-diastolic pressure 9 mm Hg. Patient weight, use of an aortic homograft valve in the conduit, stage I palliation within the first year of our experience, and low O2 extraction and high transpulmonary gradient prestage II were risk factors for overall death. Early interventions were more frequent in aortic valve conduits compared with all other conduits.

CONCLUSIONS

The valved RV-PA conduit was associated with low early mortality after the Norwood procedure. The majority of these patients had normal cardiac output and well-maintained RV function. There may be a higher risk for early conduit interventions and death when aortic valve homografts are used in the RV-PA conduit.

Perioperative management of patients with poorly functioning ventricles in the setting of the functionally univentricular heart

The patient with a functionally univentricular heart is at increased risk for ventricular dysfunction for a variety of reasons. At birth, the pulmonary and systemic circulations are in parallel, leading to pulmonary overcirculation and a volume-loaded functional ventricle. Significant atrioventricular valvar regurgitation, abnormal ventriculoarterial coupling, diastolic dysfunction, and altered ventricular geometry can also contribute to long-term ventricular dysfunction. These collected circumstances place the patient at increased risk for perioperative morbidity and mortality. We will discuss in this review the pathophysiology that leads to ventricular dysfunction at each stage of surgical palliation, as well as the strategies for perioperative management. In addition, we will highlight novel strategies for management of ventricular dysfunction.

Twenty-Four Hour Cardiopulmonary Stability in a Model of Assisted Newborn Fontan Circulation

BACKGROUND

Morbidity and mortality after stage-1 palliation of hypoplastic left heart syndrome is high as a result of adverse physiologic conditions imposed by the systemic-to-pulmonary arterial shunt. Conversion to a systemic venous source of pulmonary blood flow (Glenn/Fontan) substantially decreases instability and mortality risk. Cavopulmonary assist has the potential to eliminate critical dependence on the problematic systemic arterial shunt. We studied this support modality during a 24-hour period in a neonatal animal model of univentricular Fontan circulation.

METHODS

Lambs (8.1 +/- 0.9 kg, 8.3 +/- 2.1 days, n = 7) underwent total cavopulmonary diversion. A miniature centrifugal pump was used to assist cavopulmonary flow. Control animals (6.6 +/- 1.0 kg, 7.3 +/- 2.1 days, n = 11) underwent placement of monitoring lines only. Hemodynamic and gas exchange data were measured. Within-group and between-group comparisons were made using two-way repeated measures analysis of variance.

RESULTS

After an initial phase of reactivity, pulmonary vascular resistance returned to low levels and was not significantly different from baseline values after hour 13 or significantly different from control values after hour 4. Systemic venous pressure remained low. Oxygenation and ventilation remained normal with no histologic evidence of parenchymal lung injury.

CONCLUSIONS

Pump-assisted cavopulmonary diversion is well tolerated up to 24 hours in the neonatal period. Despite initial reactivity, pulmonary vascular resistance trended toward normal and approached control values. Cavopulmonary assist holds the potential to serve as a bridge to neonatal Fontan repair of single ventricle. Chronic studies are warranted to determine the duration and rate of weaning of support to transition to an unassisted univentricular Fontan circulation.

Coupling Pediatric Ventricle Assist Devices to the Fontan Circulation: Simulations with a Lumped-Parameter Model

In pediatric ventricular assist device (VAD) design, the process of matching device characteristics and dimensions to the relevant disease conditions poses a formidable challenge because the disease spectrum is more highly varied than for adult applications. One example arises with single-ventricle congenital defects, which demand palliative surgeries that create elevated systemic venous pressure and altered pulmonary hemodynamics. Substituting a mechanical pump as a right ventricle has long been proposed to eliminate the associated early and postoperative anomalies. A pulsatile lumped-parameter model of the single-ventricle circulation was developed to guide the preliminary design studies. Two special modules, the pump characteristics and the total cavopulmonary connection (TCPC) module, are introduced. The TCPC module incorporates the results of three-dimensional patient-specific computational fluid dynamics calculations, where the pressure drop in the TCPC anastomosis is calculated at the equal vascular lung resistance operating point for different cardiac outputs at a steady 60/40 inferior vena cava/superior vena cava flow split. Preliminary results obtained with the adult parameters are presented with no ventricle remodeling or combined larger-size single ventricle. A detailed literature review of single-ventricle function is provided. Coupling a continuous pump to the single-ventricle circulation brought both the pulmonary and systemic venous pressures back to manageable levels. Selected VADs provided an acceptable cardiac output trace of the single left ventricle, after initial transients. Remodeling of the systemic venous compliance plays a critical role in performance and is included in this study. Pulsatile operation mode with rotational speed regulation highlighted the importance of TCPC and pulmonary artery compliances. Four different pumps and three patient-specific anatomical TCPC pathologies were studied. Magnitudes of the equivalent TCPC resistances were found to be comparable to the vascular resistances of the normal baseline circulation, significantly affecting both the VAD design and hemodynamics.