Influence of ventricular morphology on outcome after the Fontan procedure

Cardiovascular Outcomes in Fontan Patients With Right vs Left Univentricular Morphology: A Multicenter Study

Background

There is a paucity of data on long-term outcomes after Fontan palliation in patients with a dominant morphological univentricular right (uRV) vs left (uLV) ventricle.

Objectives

The purpose of this study was to compare the incidence of atrial arrhythmias, thromboembolic events, cardiac transplantation, and death following Fontan palliation in patients with uRV vs uLV.

Methods

The Alliance for Adult Research in Congenital Cardiology conducted a multicenter retrospective cohort study on patients with total cavopulmonary connection Fontan palliation across 12 centers in North America. All components of the composite outcome, that is, atrial arrhythmias, thromboembolic events, cardiac transplantation, and death, were reviewed and classified by a blinded adjudicating committee. Time-to-event analyses were performed that accounted for competing risks.

Results

A total of 384 patients were followed for 10.5 ± 5.9 years. The composite outcome occurred in 3.7 vs 1.7 cases per 100 person-years for uRV (N = 171) vs uLV (N = 213), respectively (P < 0.001). In multivariable analyses, uRV conferred a >2-fold higher risk of the composite outcome (HR: 2.17, 95% CI: 1.45-3.45, P < 0.001). In secondary analyses of components of the primary outcome, uRV was significantly associated with a greater risk of cardiac transplantation or death (HR: 9.09, 95% CI: 2.17-38.46, P < 0.001) and atrial arrhythmias (HR: 2.17, 95% CI: 1.20-4.00, P = 0.010) but not thromboembolic events (HR: 1.64, 95% CI: 0.86-3.16, P = 0.131).

Conclusions

Fontan patients with uRV vs uLV morphology have a higher incidence of adverse cardiovascular events, including atrial arrhythmia, cardiac transplantation, and all-cause mortality.

MicroRNA-34a-Dependent Attenuation of Angiogenesis in Right Ventricular Failure

BACKGROUND

The right ventricle (RV) is at risk in patients with complex congenital heart disease involving right-sided obstructive lesions. We have shown that capillary rarefaction occurs early in the pressure-loaded RV. Here we test the hypothesis that microRNA (miR)-34a, which is induced in RV hypertrophy and RV failure (RVF), blocks the hypoxia-inducible factor-1α-vascular endothelial growth factor (VEGF) axis, leading to the attenuated angiogenic response and increased susceptibility to RV failure.

METHODS AND RESULTS

Mice underwent pulmonary artery banding to induce RV hypertrophy and RVF. Capillary rarefaction occurred immediately. Although hypoxia-inducible factor-1α expression increased (0.12±0.01 versus 0.22±0.03, P=0.05), VEGF expression decreased (0.61±0.03 versus 0.22±0.05, P=0.01). miR-34a expression was most upregulated in fibroblasts (4-fold), but also in cardiomyocytes and endothelial cells (2-fold). Overexpression of miR-34a in endothelial cells increased cell senescence (10±3% versus 22±2%, P<0.05) by suppressing sirtulin 1 expression, and decreased tube formation by 50% via suppression of hypoxia-inducible factor-1α, VEGF A, VEGF B, and VEGF receptor 2. miR-34a was induced by stretch, transforming growth factor-β1, adrenergic stimulation, and hypoxia in cardiac fibroblasts and cardiomyocytes. In mice with RVF, locked nucleic acid-antimiR-34a improved RV shortening fraction and survival half-time and restored capillarity and VEGF expression. In children with congenital heart disease-related RVF, RV capillarity was decreased and miR-34a increased 5-fold.

CONCLUSIONS

In summary, miR-34a from fibroblasts, cardiomyocytes, and endothelial cells mediates capillary rarefaction by suppressing the hypoxia-inducible factor-1α-VEGF axis in RV hypertrophy/RVF, raising the potential for anti-miR-34a therapeutics in patients with at-risk RVs.

Predictors of prolonged pleural effusion after Fontan operation

Prolonged pleural effusion is a fairly common condition which has considerable impact on complicated and longer hospital stays after Fontan surgery. Identifying the patient population prone to have pleural effusions is still seeking for an answer. This study is to determine the variables that may predict prolonged pleural effusion according to the data of 69 patients who underwent Fontan operation between June 2018 and December 2020 and survived to date. Prolonged pleural effusion was defined as the need for a chest tube for more than 7 days. Two patient groups, with and without prolonged effusion, were compared in terms of pre-, peri-, and post-operative variables. The patients were subdivided into "high-risk" and "low-risk" groups based on the pre-operative catheterisation data. The most frequent main diagnosis was tricuspid atresia (n: 13, 19%). Among 69 patients, 28 (40%) had prolonged pleural effusion whereas 11 (16%) had effusions that lasted longer than 14 days. Ten patients among prolonged effusion group (35%) had pulmonary atresia coexistent with the main diagnosis. Fontan operation was performed in 6 patients (8.7%) over the age of 10, and 4 of these patients (67%) had prolonged pleural effusion. Among numerous variables, statistical significance between the two groups was achieved in pre-operative mean pulmonary artery pressure, post-operative albumin, C-reactive protein levels, length of hospital stay, duration of chest tube drainage, and amount of effusion per day. Early recognition and treatment strategies with routine medical protocol use remain to be the cornerstone for the management of post-operative prolonged pleural effusions after Fontan surgery.

Longitudinal Changes in Ventricular Mechanics in Adolescents After the Fontan Operation

BACKGROUND

Ventricular dysfunction is a significant clinical challenge in the long-term follow-up of patients with single-ventricle (SV) physiology. Ventricular function and myocardial mechanics can be studied using speckle-tracking echocardiography, which provides information on myocardial deformation. Limited information is available on serial changes in SV myocardial mechanics after the Fontan operation. The aim of this study was to describe serial changes in myocardial mechanics in children after the Fontan operation and the relationship of these changes with myocardial fibrosis markers as obtained by cardiac magnetic resonance and exercise performance parameters.

METHODS

The authors hypothesized that ventricular mechanics decline in patients with SVs over time and are associated with increased myocardial fibrosis and reduced exercise performance. A single-center retrospective cohort study including adolescents after the Fontan operation was conducted. Ventricular strain and torsion were assessed using speckle-tracking echocardiography. Cardiac magnetic resonance and cardiopulmonary exercise testing data closest to the latest echocardiographic examinations were performed. The most recent follow-up echocardiographic and cardiac magnetic resonance data were compared with those from sex- and age-matched control subjects and with individual patients' early post-Fontan data.

RESULTS

Fifty patients with SVs (31 left ventricle, 13 right ventricle [RV], and six codominant) were included. Median time at follow-up echocardiography from the time of Fontan was 12.8 years (interquartile range [IQR], 10.6 to 16.6 years). Compared with early post-Fontan echocardiography, follow-up assessment showed reduced global longitudinal strain (-17.5% [IQR, -14.5% to -19.5%] vs -19.8% [IQR, -16.0% to -21.7%], P = .01], circumferential strain (-15.7% [IQR, -11.4% to -18.7%] vs -18.9% [IQR, -15.2% to -25.0%], P = .009), and torsion (1.28°/cm [IQR, 0.51°/cm to 1.74°/cm] vs 1.72°/cm [IQR, 0.92°/cm to 2.34°/cm], P = .02), with decreased apical rotation but no significant change in basal rotation. Single RVs had lower torsion compared with single left ventricles (1.04°/cm [IQR, 0.12°/cm to 2.20°/cm] vs 1.25°/cm [IQR, 0.25°/cm to 2.51°/cm], P = .01). T1 values were higher in patients with SV compared with control subjects (1,009 ± 36 vs 958 ± 40 msec, P = .004) and in those with single RVs compared with single left ventricles (1,023 ± 19 vs 1,006 ± 17 msec, P = .02). T1 was correlated with circumferential strain (r = 0.59, P = .04) and inversely correlated with O2 saturation (r = -0.67, P < .001) and torsion (r = -0.71, P = .02). Peak oxygen consumption was correlated with torsion (r = 0.52, P = .001) and untwist rates (r = 0.23, P = .03).

CONCLUSIONS

After the Fontan procedures, there is a progressive decrease in myocardial deformation parameters. The progressive decrease in SV torsion is related to a decrease in apical rotation, which is more pronounced in single RVs. Decreased torsion is associated with increased markers of myocardial fibrosis and lower maximal exercise capacity. Torsional mechanics may be an important parameter to monitor after Fontan palliation, but further prognostic information is required.

Comparative Metabolomics in Single Ventricle Patients after Fontan Palliation: A Strong Case for a Targeted Metabolic Therapy

Most studies on single ventricle (SV) circulation take a physiological or anatomical approach. Although there is a tight coupling between cardiac contractility and metabolism, the metabolic perspective on this patient population is very recent. Early findings point to major metabolic disturbances, with both impaired glucose and fatty acid oxidation in the cardiomyocytes. Additionally, Fontan patients have systemic metabolic derangements such as abnormal glucose metabolism and hypocholesterolemia. Our literature review compares the metabolism of patients with a SV circulation after Fontan palliation with that of patients with a healthy biventricular (BV) heart, or different subtypes of a failing BV heart, by Pubmed review of the literature on cardiac metabolism, Fontan failure, heart failure (HF), ketosis, metabolism published in English from 1939 to 2023. Early evidence demonstrates that SV circulation is not only a hemodynamic burden requiring staged palliation, but also a metabolic issue with alterations similar to what is known for HF in a BV circulation. Alterations of fatty acid and glucose oxidation were found, resulting in metabolic instability and impaired energy production. As reported for patients with BV HF, stimulating ketone oxidation may be an effective treatment strategy for HF in these patients. Few but promising clinical trials have been conducted thus far to evaluate therapeutic ketosis with HF using a variety of instruments, including ketogenic diet, ketone esters, and sodium-glucose co-transporter-2 (SGLT2) inhibitors. An initial trial on a small cohort demonstrated favorable outcomes for Fontan patients treated with SGLT2 inhibitors. Therapeutic ketosis is worth considering in the treatment of Fontan patients, as ketones positively affect not only the myocardial energy metabolism, but also the global Fontan physiopathology. Induced ketosis seems promising as a concerted therapeutic strategy.

Single Ventricular Torsional Mechanics After Fontan Palliation and Their Impact on Outcomes

Background

Abnormal left ventricular (LV) rotational mechanics in biventricular hearts are associated with adverse outcomes; however, these are less well characterized for hearts with functionally single ventricles.

Objectives

The purpose of this study was to characterize ventricular rotational mechanics in the Fontan circulation and their relationship to outcomes.

Methods

Single-center, retrospective analysis of magnetic resonance examinations for 329 Fontan patients (15 [IQR: 10-21] years) and 42 controls. The ventricular cine short-axis stack was analyzed to derive torsion metrics. Torsion calculated as the difference between apical and basal rotation normalized to ventricular length.

Results

Fontan patients had higher indexed ventricular end-diastolic volume (97 mL/body surface area1.3 vs 72 mL/body surface area1.3), lower ejection fraction (53% vs 60%), and lower proportion of basal clockwise rotation (62% vs 93%), apical counterclockwise rotation (77% vs 95%), and positive torsion (82% vs 100%); P < 0.001 for all. A composite outcome of death or heart transplant-listing occurred in 31 (9%) patients at a median follow-up of 3.9 years. Torsion metrics were associated with the outcome; although, on multivariate analysis only right ventricular (RV) morphology and indexed ventricular end-diastolic volume were independently associated. LVs with negative torsion, and RVs regardless of torsional pattern, had worse outcomes compared to LVs with positive torsion (P = 0.020).

Conclusions

Single ventricles in a Fontan circulation exhibit abnormal torsional mechanics, which are more pronounced for RV morphology. Abnormal torsion is associated with death or need for heart transplantation. Fontan patients with LV morphology and preserved torsion exhibit the highest transplant-free survival and torsion may offer incremental prognostic data in this group of patients.

Cardiac Transcriptome Remodeling and Impaired Bioenergetics in Single-Ventricle Congenital Heart Disease

The mechanisms responsible for heart failure in single-ventricle congenital heart disease are unknown. Using explanted heart tissue, we showed that failing single-ventricle hearts have dysregulated metabolic pathways, impaired mitochondrial function, decreased activity of carnitine palmitoyltransferase activity, and altered functioning of the tricarboxylic acid cycle. Interestingly, nonfailing single-ventricle hearts demonstrated an intermediate metabolic phenotype suggesting that they are vulnerable to development of heart failure in the future. Mitochondrial targeted therapies and treatments aimed at normalizing energy generation could represent a novel approach to the treatment or prevention of heart failure in this vulnerable group of patients.

Preoperative N-terminal pro-brain natriuretic peptide is associated with Fontan outcomes

OBJECTIVE

The role of preoperative N-terminal pro-brain natriuretic peptide level in patient outcomes after the Fontan operation remains unclear.

METHODS

The medical records of all patients who underwent their first Fontan operation from June 2011 to October 2019 in our tertiary referral pediatric cardiac center were retrospectively reviewed. Preoperative hemodynamic factors and N-terminal pro-brain natriuretic peptide were analyzed to test the association of mortality and morbidity.

RESULTS

We enrolled 110 patients (men/women 62/48; median age, 4.1 [3.4, 5.8] years; median follow-up period, 4.28 [2.31, 6.71] years). Almost all operations were extracardiac conduits (98.2%). Primary outcomes of death, Fontan takedown, and heart transplantation were observed in 9 patients (8.2%). Abnormal ventricular contractility, elevated preoperative pulmonary artery pressure, high pulmonary vascular resistance index, and high log₁₀ N-terminal pro-brain natriuretic peptide level were associated with poor outcomes.

SECONDARY OUTCOMES

atrioventricular valve regurgitation moderate or greater, elevated pulmonary artery pressure, high pulmonary vascular resistance index, and high log₁₀ N-terminal pro-brain natriuretic peptide level were associated with rehospitalization due to heart failure. Multivariable Cox regression analysis revealed that log₁₀ N-terminal pro-brain natriuretic peptide was the only significant predictor of all primary and secondary outcomes. A scoring system including factors of pulmonary artery pressure, pulmonary vascular resistance index, and N-terminal pro-brain natriuretic peptide was established, and the risk stratification is associated with outcomes after the Fontan operation.

CONCLUSIONS

High preoperative N-terminal pro-brain natriuretic peptide was associated with poor outcomes after the Fontan operation.

Fontan procedure on deep hypothermic circulatory arrest: Short-term results and technique

Background

Various operative strategies are described for the Fontan procedure. In this study, we describe our short-term results and technique of Fontan procedure on cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA).

Methods

This was a retrospective study of 32 patients, median age of 6 years (4-19 years) and median weight of 20 kg (13-51 kg), who underwent Fontan procedure on CPB and DHCA from July 2016 to July 2021.

Results

The median CPB time was 125 min (77-186 min), the median DHCA time was 42 min (27-50 min), and the median Fontan pressure was 14 mmHg (10-18 mmHg). The median time to extubation was 4 h (1-20 h), the duration of chest tube drainage was 8 days (5-24 days), and the median intensive care unit stay was 4 days (3-8 days). The presence of heterotaxy was associated with longer duration of pleural drainage (P = 0.01). There was no operative mortality and no major adverse events such as seizures, gross neurological deficits, or arrhythmias in the postoperative period.

Conclusions

Fontan procedure can be safely performed on CPB and DHCA with good operative results. This operative strategy may be used in special circumstances like in patients with situs and systemic venous anomalies and those requiring repair of a complex intracardiac defect. Long-term follow-up will be required to evaluate if this strategy has any impact on the neurodevelopmental outcome and the long-term sequelae of Fontan.

Failures of the Fontan System in Univentricular Hearts and Mortality Risk in Heart Transplantation: A Systematic Review and Meta-Analysis

The Fontan procedure (FP) is the standard surgical treatment for Univentricular heart diseases. Over time, the Fontan system fails, leading to pathologies such as protein-losing enteropathy (PLE), plastic bronchitis (PB), and heart failure (HF). FP should be considered as a transitional step to the final treatment: heart transplantation (HT). This systematic review and meta-analysis aims to establish the risk of death following HT according to the presence of FP complications. There was a total of 691 transplanted patients in the 18 articles, immediate survival 88% (n = 448), survival from 1 to 5 years of 78% (n = 427) and survival from 5.1 to 10 years of 69% (n = 208), >10 years 61% (n = 109). The relative risk (RR) was 1.12 for PLE (95% confidence interval [CI] = 0.89-1.40, p = 0.34), 1.03 for HF (0.7-1.51, p = 0.88), 0.70 for Arrhythmias (0.39-1.24, p = 0.22), 0.46 for PB (0.08-2.72, p = 0.39), and 5.81 for CKD (1.70-19.88, p = 0.005). In patients with two or more failures, the RR was 1.94 (0.99-3.81, p = 0.05). After FP, the risk of death after HT is associated with CKD and with the presence of two or more failures.

Perioperative Right Ventricular Dysfunction: Analysis of Outcomes

Right ventricular dysfunction (RVD) is a well-known prognostic factor for adverse outcomes in cardiovascular medicine. The right ventricle (RV) in medically managed heart failure patients and in surgical patients perioperatively generally is overshadowed by left ventricular disease. However, with advancement of various diagnostic tools and better understanding of its functional anatomy, the role of the RV is emerging in many clinical conditions. The failure of one ventricle has significant effect on the function of the other ventricle and it is predominantly due to ventricular interdependence.¹ The etiology of RVD is multifactorial and irrespective of etiology. RVD has been associated with significant increases in morbidity and mortality in various clinical scenarios.^2,3 The primary objective of this comprehensive review is to analyze various etiology-related outcomes of RVD in the perioperative population.

Quality of life of adult Fontan patients

BACKGROUND

Progress in the management of complex congenital heart disease (CHD) led to an improvement in survival rates of adults with a Fontan-like circulation. The objective of this study was to assess the subjective health status and quality of life of this population.

METHODS AND RESULTS

Patients aged more than 18 years at the time of the study, who underwent a Fontan-like procedure. Subjective health status was assessed by the SF-36 questionnaire and a linear analog scale was used to score patients' self-perception of their quality of life; cardiac and demographic parameters were collected.

RESULTS

Among 65 eligible patients, 60 (23 females; mean ± SD age: 25.7 ± 7.2 years) answered the SF-36 questionnaire and 46 of these were interviewed to evaluate their perceived quality of life. Among them, 20 (33.3%) were working full-time and 21 (35%) experienced arrhythmias. The physical SF-36 scores were lower in patients than in the general population (p ≤ 0.05). The New York Hear Association (NYHA) class and occupation were correlated with SF-36 scores of physical activity (respectively, p = 0.0001 and p = 0.025). SF-36 scores of psychological status were associated with the number of drugs and occupation (respectively, p = 0.0001 and p = 0.02). The mean ± SD quality of life score measured using a linear analog scale was 7.02 ± 1.6 and was linked to education and occupation (p ≤ 0.05) but not with cardiac parameters.

CONCLUSION

Adult Fontan patients perceive an impaired physical health but report a good overall quality of life. Education and occupation impacts significantly on Fontan patients' quality of life.

Higher Incidence of Protein-Losing Enteropathy in Patients with Single Systemic Right Ventricle

Patients with single ventricle congenital heart disease are at risk of unpredictable protein-losing enteropathy (PLE) after surgical palliation. Based on prior reports of physiologic differences for patients with single morphologic right versus left ventricles, we hypothesized that those with right ventricular morphology would have a higher incidence of PLE. We performed a retrospective review of > 15 million pediatric hospitalizations from the Healthcare Cost and Utilization Project KID 2000-2012 databases for admissions 5-21 years old with ICD-9 codes for hypoplastic left heart syndrome (HLHS) and tricuspid atresia (TA) with and without PLE. Incidence of PLE was compared between those with HLHS and TA. In addition, outcomes and costs were compared between admissions with and without PLE and between HLHS and TA. Of 1623 HLHS admissions, 289 (17.8%) had PLE, and of 926 TA admissions, 58 (5.9%) had PLE (p < 0.001). Admissions with PLE were older compared to those without PLE (12 vs 10 years, p < 0.001) and PLE onset occurred at a younger age for HLHS than TA (11 vs 14 years, p < 0.001). There were no differences in hospital outcomes or costs. Review of this large administrative database suggests a higher incidence of PLE in patients with HLHS and a younger age of onset compared to those with TA. These data suggest that a single systemic right ventricle may be an independent risk factor for developing PLE.

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.

Molecular Approaches in Single Ventricle Management

Advances in medical and surgical management have significantly improved early outcomes in single ventricle congenital heart disease over the last 2 decades. Despite these advances, long-term outcomes remain suboptimal and therapeutic options to address systemic ventricular and/or Fontan failure are limited even in the modern era. Intricate molecular biologic techniques have shed light into the mechanisms of development of single ventricle disease. Efforts are underway to leverage this knowledge to improve clinical diagnosis, therapy, and prognostication. Cell-based therapies aimed at inducing cardiomyocyte proliferation and preventing delayed cardiac dysfunction have already entered the clinical realm. Several more novel biological therapies are expected to become available for patients with single ventricle disease in the near future. These scientific advancements provide us hope and reaffirm our faith that molecular medicine will usher in the next generation of therapies for single ventricle management.

Resolving the natural myocardial remodelling brought upon by cardiac contraction; a porcine ex-vivo cardiovascular magnetic resonance study of the left and right ventricle

BACKGROUND

The three-dimensional rearrangement of the right ventricular (RV) myocardium during cardiac deformation is unknown. Previous in-vivo studies have shown that myocardial left ventricular (LV) deformation is driven by rearrangement of aggregations of cardiomyocytes that can be characterised by changes in the so-called E3-angle. Ex-vivo imaging offers superior spatial resolution compared with in-vivo measurements, and can thus provide novel insight into the deformation of the myocardial microstructure in both ventricles. This study sought to describe the dynamic changes of the orientations of the cardiomyocytes in both ventricles brought upon by cardiac contraction, with particular interest in the thin-walled RV, which has not previously been described in terms of its micro-architecture.

METHODS

The hearts of 14 healthy 20 kg swine were excised and preserved in either a relaxed state or a contracted state. Myocardial architecture was assessed and compared between the two contractional states by quantification of the helical, transmural and E3-angles of the cardiomyocytes using high-resolution diffusion tensor imaging.

RESULTS

The differences between the two states of contraction were most pronounced in the endocardium where the E3-angle decreased from 78.6° to 24.8° in the LV and from 82.6° to 68.6° in the RV. No significant change in neither the helical nor the transmural angle was found in the cardiomyocytes of the RV. In the endocardium of the LV, however, the helical angle increased from 35.4° to 47.8° and the transmural angle increased from 3.1° to 10.4°.

CONCLUSION

The entire myocardium rearranges through the cardiac cycle with the change in the orientation of the aggregations of cardiomyocytes being the predominant mediator of myocardial wall thickening. Interestingly, differences also exist between the RV and LV, which helps in the explanation of the different physiological capabilities of the ventricles.

Echocardiographic evaluation of univentricular physiology and cavopulmonary shunts

Since the surgical palliation of a univentricular congenital heart defect was first described in the early 1970s, thousands of lives were saved by this groundbreaking operation. Although initially described for the palliation of tricuspid valve atresia, the Fontan operation is now utilized for many other univentricular heart defects involving either hypoplastic right or left ventricles, and the number of babies who survive the surgery and the postsurgical hospitalization continues to grow. Echocardiography constitutes the mainstay follow-up imaging modality for patients with a Fontan system. In order to obtain all the needed information from the echocardiographic studies, close familiarity with the native congenital heart defects, the build of the Fontan systems, and the potential long-term complications is required. Detailed studies provide valuable information on the various components of the Fontan circulation such as the function of the single ventricle and the valves, flow in the Glenn and Fontan pathways, and possible sources of cyanosis and shunts. Three-dimensional and transesophageal echocardiogram studies can assist in delineating the Fontan anatomy and to evaluate smaller intracardiac structures.

Systemic ventricle morphology impact on ten-year survival after Fontan surgery

BACKGROUND

The Fontan procedure has been applied in many patients with single-ventricle physiology, with quite low mortality rates all over the world, and a 8.6%-9.1% rate in Indonesia. Structural and characteristic differences in the morphologically left and right ventricles influence the role of the systemic ventricle in the functionally univentricular heart and impact on postoperative outcomes. Mid- and long-term survival based on systemic ventricle morphology remains controversial. This study aimed to investigate the impact of systemic ventricle morphology on ten-year survival after the Fontan procedure.

METHODS

The 162 patients who underwent a Fontan operation at our institution between 2008 and February 2018 and survived to discharge were reviewed and followed up until March 2018. Data were extracted from the registry and pediatric surgical conferences, medical records, surgery reports, echocardiography and catheterization reports, and follow-up to the end of the study period. Median follow-up was 26.5 months (range 10.75-54 months).

RESULTS

The patients were divided into 2 groups based on systemic ventricle morphology. Seventy-four patients were included in the left morphology group and 88 in the right morphology group. There was no difference in 10-year survival rates between the two type of systemic ventricle morphology. Postoperative thromboembolic events influenced the 10-year survival rate after the Fontan procedure (hazard ratio 4.84, 95% confidence interval: 1.26-18.55, p = 0.021).

CONCLUSION

Systemic ventricle morphology was not associated with the 10-year survival rate after the Fontan procedure. Postoperative thromboembolic events accounted for a 4.84-times higher mortality risk after the Fontan procedure.

Evaluation and Management of Right-Sided Heart Failure: A Scientific Statement From the American Heart Association

Background and Purpose:

The diverse causes of right-sided heart failure (RHF) include, among others, primary cardiomyopathies with right ventricular (RV) involvement, RV ischemia and infarction, volume loading caused by cardiac lesions associated with congenital heart disease and valvular pathologies, and pressure loading resulting from pulmonic stenosis or pulmonary hypertension from a variety of causes, including left-sided heart disease. Progressive RV dysfunction in these disease states is associated with increased morbidity and mortality. The purpose of this scientific statement is to provide guidance on the assessment and management of RHF.

Methods:

The writing group used systematic literature reviews, published translational and clinical studies, clinical practice guidelines, and expert opinion/statements to summarize existing evidence and to identify areas of inadequacy requiring future research. The panel reviewed the most relevant adult medical literature excluding routine laboratory tests using MEDLINE, EMBASE, and Web of Science through September 2017. The document is organized and classified according to the American Heart Association to provide specific suggestions, considerations, or reference to contemporary clinical practice recommendations.

Results:

Chronic RHF is associated with decreased exercise tolerance, poor functional capacity, decreased cardiac output and progressive end-organ damage (caused by a combination of end-organ venous congestion and underperfusion), and cachexia resulting from poor absorption of nutrients, as well as a systemic proinflammatory state. It is the principal cause of death in patients with pulmonary arterial hypertension. Similarly, acute RHF is associated with hemodynamic instability and is the primary cause of death in patients presenting with massive pulmonary embolism, RV myocardial infarction, and postcardiotomy shock associated with cardiac surgery. Functional assessment of the right side of the heart can be hindered by its complex geometry. Multiple hemodynamic and biochemical markers are associated with worsening RHF and can serve to guide clinical assessment and therapeutic decision making. Pharmacological and mechanical interventions targeting isolated acute and chronic RHF have not been well investigated. Specific therapies promoting stabilization and recovery of RV function are lacking.

Conclusions:

RHF is a complex syndrome including diverse causes, pathways, and pathological processes. In this scientific statement, we review the causes and epidemiology of RV dysfunction and the pathophysiology of acute and chronic RHF and provide guidance for the management of the associated conditions leading to and caused by RHF.

Life After Surviving Fontan Surgery: A Meta-Analysis of the Incidence and Predictors of Late Death

AIM

We now know that 20-40% of patients with a single ventricle will develop heart failure after the second decade post-Fontan surgery. However, we remain unable to risk-stratify the cohort to identify patients at highest risk of late failure and death. We conducted a systematic review of all reported late outcomes for patients with a Fontan circulation to identify predictors of late death.

METHODS

We searched MEDLINE, Embase and PubMed with subject terms ("single ventricle", "Hypoplastic left heart syndrome", "congenital heart defects" or "Fontan procedure") AND ("heart failure", "post-operative complications", "death", "cause of death", "transplantation" or "follow-up studies") for relevant studies between January 1990 and December 2015. Variables identified as significant predictors of late death on multivariate analysis were collated for meta-analysis. Survival data was extrapolated from Kaplan-Meier survival curves to generate a distribution-free summary survival curve.

RESULTS

Thirty-four relevant publications were identified, with a total of 7536 patients included in the analysis. Mean follow-up duration was 114 months (range 24-269 months). There were 688 (11%) late deaths. Predominant causes of death were late Fontan failure (34%), sudden death (19%) and perioperative death (16%). Estimated mean survival at 5, 10 and 20 years post Fontan surgery were 95% (95%CI 93-96), 91% (95%CI 89-93) and 82% (95%CI 77-85). Significant predictors of late death include prolonged pleural effusions post Fontan surgery (HR1.18, 95%CI 1.09-1.29, p<0.001), protein losing enteropathy (HR2.19, 95%CI 1.69-2.84, p<0.001), increased ventricular end diastolic volume (HR1.03 per 10ml/BSA increase, 95%CI 1.02-1.05, p<0.001) and having a permanent pacemaker (HR12.63, 95%CI 6.17-25.86, p<0.001).

CONCLUSIONS

Over 80% of patients who survive Fontan surgery will be alive at 20 years. Developing late sequelae including protein losing enteropathy, ventricular dysfunction or requiring a pacemaker predict a higher risk of late death.

Systemic right ventricular morphology in the early postoperative course after extracardiac Fontan operation: is there still a need for special care?

Objectives

We aimed to compare early postoperative outcome after extracardiac (EC) Fontan operation between patients with right (RV) or left (LV) systemic ventricles.

Methods

In total, 173 consecutive patients (median age 4 years, median weight 14 kg) underwent EC Fontan between 1995 and 2013. Pre- and intraoperative data as well as detailed postoperative haemodynamic variables were compared between patients with LV [ n  = 109 (63%)] and RV [ n  = 64 (37%)].

Results

: RV patients showed significantly lower mean arterial (median 55 vs 59 mmHg, P  = 0.04), higher atrial (median 8 vs 6 mmHg, P  = 0.03) and comparable pulmonary pressure (median 14 vs 14 mmHg, P  = 0.7) as well as lower mean systemic perfusion pressure (median 39 vs 43 mmHg, P  = 0.03) on Day 0 after EC Fontan. They suffered from longer intubation time (median 18 vs 12 h, P  = 0.008), higher incidence of ascites (46% vs 28%, P  = 0.04) and need for dialysis (21% vs 4%, P  = 0.003). Prolonged inotropic support (25% vs 8%, P  = 0.02) and pharmacological treatment to reduce pulmonary vascular resistance (71% vs 53%, P  = 0.002) were more often used in RV patients and they showed more often supraventricular tachyarrhythmia (27% vs 5%, P  < 0.001) and a longer intensive care unit-stay (median 4 vs 3 days, P  = 0.03). However, early mortality, need for Fontan takedown, use of mechanical circulatory support, pleural effusions and hospital stay were not significantly different between both groups.

Conclusions

Patients with systemic RV demonstrate higher morbidity in the early postoperative course compared with patients with systemic LV anatomy and require intensified postoperative management to avoid postoperative Fontan failure.

Effect of Fenestration on Early Postoperative Outcome in Extracardiac Fontan Patients with Different Risk Levels

Although fenestration is used to improve the postoperative course of Fontan patients, the effect of fenestration on the extracardiac Fontan seems controversial especially at early postoperation. One hundred and eighty-three patients from January 2004 to June 2013 undergoing an extracardiac Fontan operation were retrospectively selected for this study. We divided the patients into low risk (93 patients) and high risk (90 patients) groups according to the risk factors recognized by previous studies and then compared the perioperative data between the nonfenestrated and fenestrated patients in each group. In both groups there was no significant difference in preoperative and operative data between the nonfenestrated and fenestrated patients. The postoperative blood oxygen saturation of fenestrated patients was significantly lower (p < 0.01) in each group. In the high risk group the chest tube volume (1153 mL vs. 1739 mL, p = 0.021) and chest tube duration (11.9 days vs. 17.0 days, p = 0.028) of fenestrated patients were lower comparing to nonfenestrated patients, while the chest tube volume and chest tube duration were similar between the nonfenestrated and fenestrated patients in the low risk group. The morbidity and mortality of nonfenestrated and fenestrated patients were similar in both groups (p > 0.05). Although fenestration was associated with lower postoperative oxygen saturation, fenestration showed better postoperative outcomes regarding the chest tube volume and duration for the high-risk patients. Considering the similar early postoperative outcomes of nonfenestrated and fenestrated patients in low risk group, our data indicate that fenestration for the high-risk patients should be performed.

Risk Factors for Increased Hospital Resource Utilization and In-Hospital Mortality in Adults With Single Ventricle Congenital Heart Disease

Most patients with single ventricle congenital heart disease are now expected to survive to adulthood. Co-morbid medical conditions (CMCs) are common. We sought to identify risk factors for increased hospital resource utilization and in-hospital mortality in adults with single ventricle. We analyzed data from the 2001 to 2011 Nationwide Inpatient Sample database in patients aged ≥18 years admitted to nonteaching general hospitals (NTGHs), TGHs, and pediatric hospitals (PHs) with either hypoplastic left heart syndrome, tricuspid atresia or common ventricle. National estimates of hospitalizations were calculated. Elixhauser CMCs were identified. Length of stay (LOS), total hospital costs, and effect of CMCs were determined. Age was greater in NTGH (41.5 ± 1.3 years) than in TGH (32.8 ± 0.5) and PH (25.0 ± 0.6; p <0.0001). Adjusted LOS was shorter in NTGH (5.6 days) than in PH (9.7 days; p <0.0001). Adjusted costs were higher in PH ($56,671) than in TGH ($31,934) and NTGH ($18,255; p <0.0001). CMCs are associated with increased LOS (p <0.0001) and costs (p <0.0001). Risk factors for in-hospital mortality included increasing age (odds ratio [OR] 5.250, CI 2.825 to 9.758 for 45- to 64-year old vs 18- to 30-year old), male gender (OR 2.72, CI 1.804 to 4.103]), and the presence of CMC (OR 4.55, CI 2.193 to 9.436) for 2 vs none). No differences in mortality were found among NTGH, TGH, and PH. Cardiovascular procedures were more common in PH hospitalizations and were associated with higher costs and LOS. CMCs increase costs and mortality. In-hospital mortality is increased with age, male gender, and the presence of hypoplastic left heart syndrome.

Role of imaging in the evaluation of single ventricle with the Fontan palliation

The Fontan operation for single ventricle palliation consists of the creation of a complete cavopulmonary connection, usually by incorporating inferior vena caval flow into a pulmonary arterial circulation already receiving flow from the superior vena cava. In single ventricle palliated in this way, the anatomy is complex, and the pathophysiological complications are frequent; so, cardiac imaging is a key aspect of clinical surveillance. Common problems that echocardiography and MRI may disclose and characterise in the Fontan palliation of single ventricle include obstruction of systemic venous and pulmonary arterial flow, atrioventricular and semilunar valve dysfunction, unintended collateral flow patterns, ventricular dysfunction, aortic arch obstruction, interatrial obstruction, fenestration flow and patch leaks. Despite the broad scope of these modalities for detection of such problems, often no single imaging method is comprehensive in any given patient. Therefore, physicians must recognise the limitations of each modality, and circumvent these by application of suitable alternatives. New imaging tools are becoming available, which may ultimately prove to be of value in the Fontan circulation. Proper application of diverse new technologies such as four dimensional flow, computational fluid dynamics and three-dimensional printing will require critical evaluation in the single ventricle population.

The vulnerable right ventricle

PURPOSE OF REVIEW

The right ventricle (RV) is uniquely at risk in many patients with repaired or palliated congenital heart disease (CHD) such as tetralogy of Fallot, corrected transposition, single right ventricle, and in those with pulmonary hypertension. These patients live with abnormal cardiac loading conditions throughout their life, predisposing them to right heart failure.

RECENT FINDINGS

Standard heart failure therapies, developed to treat left ventricular failure, have failed to improve function or survival in patients with RV failure, suggesting a divergence in the molecular mechanisms of right versus left ventricular failure. As surgical techniques for repair of the most complex forms of RV-affecting CHDs continue to improve, more children with CHD will survive into adulthood. Long-term survival and quality of life will ultimately depend on our ability to preserve RV function.

SUMMARY

The purpose of this review is to highlight the differences between the right and left ventricular responses to stress, our current knowledge of how the RV adapts to the unique hemodynamic stressors experienced by patients with CHD, and the need to better understand the molecular mechanisms of RV failure, providing new targets for the development of RV-specific heart failure therapeutics.

Ventricular morphology is a determinant of diastolic performance in patients with single ventricle physiology undergoing stage 3 palliative surgery

Patients with single ventricle anatomy undergo staged surgical palliation which results in pulmonary and systemic circulations in series with a single systemic pump. Single right ventricular morphology has been found to be an independent risk factor for worse survival. We sought to compare patients with single left (SLV) and single right (SRV) ventricular morphology to identify hemodynamic differences that may contribute to worse survival in patients with a single right ventricular. Single center, retrospective review of invasive hemodynamic data. All patients with single ventricle anatomy who underwent superior cavo-pulmonary anastomosis (Stage 2 palliation) and/or total cavo-pulmonary anastomosis (Stage 3 palliation) from August 1995 through May 2011 were identified. Patients were compared over time, and SLV and SRV patients were compared. Seventy-nine single ventricle patients (56 % SRV) underwent staged palliation and were analyzed. There was no difference in overall mortality (12 % SLV, 11 % SRV). There was no difference in hemodynamics at pre-Stage 2 catheterization between ventricular morphology, but SRV patients had higher ventricular end-diastolic pressure at pre-Stage 3 catheterization (7.6 vs. 6.4 mmHg, p = 0.026). End-diastolic pressure decreased after Stage 2 surgery for SLV patients, but not SRV patients. Intrinsic differences in morphology, function, and response to performing as the systemic ventricle between single right and left ventricles may lead to an elevated ventricular end-diastolic pressure. This could limit passive flow through the pulmonary circuit and coronary perfusion after Stage 3 palliation and potentially lead to poorer long-term performance for SRV patients.

Echocardiographic evaluation of univentricular physiology and cavopulmonary shunts

The term univentricular heart (UH) defines complex congenital heart disease that lacks a pulmonic ventricular chamber either in the original anatomy or the final palliation. The prevalence of patients with this type of physiology continues to increase due to improved surgical palliative procedures. This review will outline the physiology, complications, and echocardiographic approach to image patients with palliated UH.

Comparison of fenestrated and nonfenestrated patients undergoing extracardiac Fontan

BACKGROUND

The purpose of this study is to compare morbidity and mortality between fenestrated (F, 61 patients) and nonfenestrated (NF, 54 patients) extracardiac Fontan patients during two eras from July 1995 to December 2010: era 1(1995 to 2004) and era 2 (2005 to 2010).

METHODS

Variables evaluated included morphology, hemodynamics, chest tube volume and duration, intensive care and hospital stay, oxygen saturation, neurologic events, rhythm, and readmissions for chylous effusions. Follow-up in 114 hospital survivors was longer in the nonfenestrated cohort (F, 5.0 ± 3.3 years; NF, 7.1 ± 4.6 years; p < 0.005).

RESULTS

Cohorts were similar in body size, morphology, and hemodynamics. Fenestration in hypoplastic left heart syndrome was appreciatively higher in era 2. Bypass time (F, 69 ± 27 minutes; NF, 57 ± 21 minutes) and conduit size (F, 18.8 mm; NF, 19.1 mm) were similar. There was 1 early nonfenestrated Fontan death (1 of 54; 2%) and 4 late deaths (F, 2 of 61, 5%; NF, 2 of 53, 4%; p = 0.86). Room air saturation was higher in NF patients (F, 89%; NF, 94%; p < 0.05). Total chest tube volume was similar, but fenestration was associated with greater chest tube drainage among hypoplastic left heart patients (HLHS, 5,582 ± 3,286 mL; non-HLHS, 3,405 ± 2,533 mL; p = 0.06; odds ratio; 2.0). Readmission to treat chylous effusions, loss of sinus rhythm, actuarial freedom from death, all neurologic events, pacemaker insertion, and Fontan takedown were similar in both cohorts.

CONCLUSIONS

Fenestration was associated with lower discharge oxygen saturations, but late outcomes in fenestrated and nonfenestrated patients are equivalent.

Evaluating failing Fontans for heart transplantation: predictors of death

BACKGROUND

Late complications of the Fontan operation represent a significant management challenge. Failing Fontan patients have two modes of presentation: impaired ventricular function (IVF) and those with preserved ventricular function (PVF) but with failing Fontan physiology (protein-losing enteropathy [PLE] and plastic bronchitis [PB]). This study evaluated whether failing Fontan patients referred for heart transplantation had a different outcome based on the mode of presentation.

METHODS

The medical records of all Fontan patients evaluated for heart transplantation at a single institution from 1994 to 2008 were retrospectively reviewed. Demographic, hemodynamic, and laboratory data were collected. Patients were stratified into an IVF or PVF group by echocardiographic criteria. Descriptive statistics and Kaplan-Meier analysis were used for hypothesis testing.

RESULTS

Thirty-four Fontan patients were evaluated for heart transplantation. According to echo description of systolic function, 18 were categorized as IVF and 16 as PVF. The IVF group had a significantly lower cardiac index and venous oxygen saturation, and significantly higher systemic vascular resistance vs the PVF group (p < 0.05). PLE or PB was present in 13 PVF patients and none in the IVF group. Twenty patients underwent transplantation, with similar rates amongst the IVF and PVF groups. Within 1 year from evaluation, 2 IVG patients and 7 PVF patients had died (p = 0.052).

CONCLUSIONS

Failing Fontan patients with PVF have decreased overall survival independent of whether they underwent transplantation. This trend indicates a need to improve the management and timing for transplantation amongst this population.

Impact of age at Fontan completion on postoperative hemodynamics and long-term aerobic exercise capacity in patients with dominant left ventricle

BACKGROUND

Although the Fontan procedure is now being applied to younger patients, the influence of patients' age at the time of surgery on long-term results remains unclear. We investigated whether age at Fontan completion affects subsequent hemodynamics and exercise capacity in patients with a dominant left ventricle followed up for more than 5 years.

METHODS

Between January 1990 and December 2001, 68 patients with a dominant left ventricle underwent total cavopulmonary connection (TCPC) at our institute. The survivors routinely underwent postoperative exercise tests and catheterization at 1 year and then every 5 years after TCPC, and were divided into group A (< 3 years; n = 32) and group B (> or = 3 years; n = 33), according to age at time of the Fontan procedure and retrospectively reviewed. We also examined the correlation between age at Fontan and data from postoperative catheterization or exercise tests.

RESULTS

None of the patients died during a follow-up period of 91.2 +/- 46.7 months. The postoperative exercise capacity (peak oxygen consumption; % of normal [61.3 +/- 11.5 versus 51.9 +/- 9.1, p = 0.0001]), cardiac index at 5 years (3.31 +/- 0.62 versus 2.86 +/- 0.69, p = 0.0133) and at 10 years after TCPC (3.24 +/- 0.46 versus 2.61 +/- 0.65, p = 0.0194), and ventricular ejection fraction (%) at 10 years after TCPC (62.1 +/- 7.6 versus 53.0 +/- 8.0, p = 0.0131) were significantly higher in group A. Age at Fontan completion inversely correlated with postoperative peak oxygen consumption (R = -0.374, p = 0.0006) and cardiac index at 5 years (R = -0.452, p = 0.0003) and 10 years after TCPC (R = -0.491, p = 0.0072).

CONCLUSIONS

Earlier TCPC is beneficial in the long term from the viewpoint of exercise capacity and hemodynamics among patients with a dominant left ventricle.

Factors associated with prolonged recovery after the fontan operation

BACKGROUND

Mortality and major morbidity after the Fontan operation is low in the current era. However, factors contributing to prolonged postoperative recovery are not clearly understood.

METHODS AND RESULTS

Data on all patients admitted to the cardiac intensive care unit (CICU) after a Fontan operation between June 2001 and December 2005 were retrospectively analyzed. We excluded all patients who died, required Fontan takedown, or required ECMO. The study cohort was further divided into a prolonged recovery group that included patients with >75%ile for duration of mechanical ventilation or pleural drainage, and a standard recovery group which included all other patients. A multivariable logistic regression model was used to compare demographic, anatomic, and physiological variables between the prolonged and standard recovery groups. There were 226 Fontan operations performed. Of the study population (n=218), the median age was 2.61 years (1.0 to 31.9 years) and weight was 12.45 kg (8.4 to 77.5 kg). The most common diagnosis was hypoplastic left heart syndrome (n=80, 36.7%). A systemic right atrioventricular valve was present in 139 (63.7%). The lateral tunnel fenestrated Fontan was the most common surgery (n=195, 89.4%). Within the study population, 81 (38%) patients meet criteria for prolonged recovery. Univariate risk factors for prolonged recovery included higher preoperative PVR (P=0.033), longer bypass times (P=0.009), higher postbypass lactate level (P=0.017), higher postoperative central venous (P<0.001) common atrial pressure (P=0.042), inotropic score (P<0.001), and need for greater volume resuscitation during the 24 postoperative hours (>75% for the entire group; P<0.001). In a multivariable model, need for greater volume resuscitation (OR 2.81, 95% CI 1.30, 6.05) was the only independent risk factor for prolonged outcome after the Fontan operation.

CONCLUSIONS

High volume expansion in the early postoperative period is an independent risk factor for prolonged recovery. The need for high volume expansion may represent the compound effects of multiple risk factors including preoperative hemodynamics and a marked systemic inflammatory response to surgery and cardiopulmonary bypass, which in turn may mediate prolonged recovery.

Long-term clinical outcome of atrial isomerism after univentricular repair

OBJECTIVES

We retrospectively reviewed the long-term outcome of atrial isomerism patients after Fontan completion.

METHODS

Since 1972, 58 patients underwent a palliative procedure prior to the Fontan-type operation. Twenty-eight out of 58 patients could not reach Fontan-type operation. Twenty-five patients underwent Fontan-type operation, and 12 of them expired less than five years after the Fontan completion. Eleven patients survived more than five years after the Fontan completion and were identified as long-term survivors. The mean follow-up period was 13+/-5 years.

RESULTS

During follow-up period, four of the 11 patients expired. The actuarial survival rates at 10, 15, and 20 years after univentricular repair (UVR) were 100%, 71.4%, and 53.6%, respectively. The significant predictors of long-term survival by univariate analysis were the staged strategy (p=0.019), total cavo-pulmonary connection with extracardiac conduit (p=0.019), and the absence of postoperative common atrioventricular valve regurgitation (p=0.040). Six out of the seven present survivors showed New York Heart Association class I activity. All present survivors' mean percutaneous oxygen saturation, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, single ventricular end diastolic volume index, and single ventricular ejection fraction were 88.8+/-6.8%, 11.0+/-2.6 mmHg, 5.8+/-2.0 mmHg, 104+/-37 mL/m2, and 52.0+/-6.5%, respectively.

CONCLUSIONS

There are still life-threatening problems 10 years after the UVR. However, the excellent performance status of the present long-term survivors suggests that these problems can all be overcome by the present strategies established for the Fontan-type operation.

Usefulness of cardiac magnetic resonance imaging combined with low-dose dobutamine stress to detect an abnormal ventricular stress response in children and young adults after fontan operation at young age

After Fontan operation, patients are limited in increasing cardiac output and in exercise capacity. This has been related to impaired preload or other factors leading to decreased global ventricular performance with stress. To study these factors, the stress responses of functionally univentricular hearts were assessed at rest and during low-dose dobutamine stress using cardiovascular magnetic resonance imaging. Thirty-two patients after Fontan completion at young age were included (27 with total cavopulmonary connection, 5 with atriopulmonary connection; mean age 13.3 years, range 7.5 to 22.2; 23 male patients; median follow-up after Fontan operation 8.1 years, range 5.2 to 17.8). A multiphase short-axis stack of 10 to 12 contiguous slices of the systemic ventricle was obtained at rest and during low-dose dobutamine stress cardiovascular magnetic resonance imaging (maximum 7.5 microg/kg/min). With stress-testing, heart rate, ejection fraction, and cardiac index increased adequately (p <0.001). There was an abnormal decrease in end-diastolic volume and an adequate decrease in end-systolic volume (p <0.001). Stroke volume did not change with stress testing (p = 0.15). At rest, dominant left ventricles had higher ejection fractions than dominant right ventricles (p = 0.01), but this difference disappeared with stress testing. In conclusion, a functionally univentricular heart after Fontan completion at young age has an adequate increase in ejection fraction with beta-adrenergic stimulation. However, as a result of impaired preload with stress, cardiac output can be increased only by increasing heart rate.

Long-term survival, modes of death, and predictors of mortality in patients with Fontan surgery

BACKGROUND

To better define determinants of mortality in patients with univentricular physiology, a database registry was created of patients born in 1985 or earlier with Fontan surgery who were followed up at Children's Hospital Boston.

METHODS AND RESULTS

A total of 261 patients, 121 of whom (46.4%) were women, had a first Fontan surgery at a median age of 7.9 years: right atrium-to-pulmonary artery connection in 135 (51.7%); right atrium to right ventricle in 25 (9.6%); and total cavopulmonary connection in 101 (38.7%). Over a median of 12.2 years, 76 (29.1%) died, 5 (1.9%) had cardiac transplantation, 5 (1.9%) had Fontan revision, and 21 (8.0%) had Fontan conversion. Perioperative mortality decreased steadily over time and accounted for 68.4% of all deaths. In early survivors, actuarial freedom from death or transplantation was 93.7%, 89.9%, 87.3%, and 82.6% at 5, 10, 15, and 20 years, respectively, with no significant difference between right atrium to pulmonary artery versus total cavopulmonary connection. Late deaths were classified as sudden in 7 patients (9.2%), thromboembolic in 6 (7.9%), heart failure-related in 5 (6.7%), sepsis in 2 (2.6%), and other in 4 (5.2%). Most sudden deaths were of presumed arrhythmic origin with no identifiable predictor. Independent risk factors for thromboembolic death were lack of antiplatelet or anticoagulant therapy (hazard ratio [HR], 91.6; P=0.0041) and clinically diagnosed intracardiac thrombus (HR, 22.7; P=0.0002). Independent predictors of heart failure death were protein-losing enteropathy (HR, 7.1; P=0.0043), single morphologically right ventricle (HR, 10.5; P=0.0429), and higher right atrial pressure (HR, 1.3 per 1 mm Hg; P=0.0016).

CONCLUSIONS

In perioperative survivors of Fontan surgery, gradual attrition occurs predominantly from thromboembolic, heart failure-related, and sudden deaths.

Long-term results of the Fontan operation

Modifications of the Fontan operation can afford excellent palliation for many patients with a variety of forms of single ventricle. In properly selected patients who are good candidates, early and late survival can be as high as 95-97%. However, mortality is considerably higher for patients with risk factors for poor outcome. For high-risk patients, inclusion of a fenestration may reduce morbidity and mortality. Important long-term undesirable events include the ongoing risk of death, arrhythmias, protein-losing enteropathy, and cardiac failure. The key to excellent long-term outcome is proper selection of patients for the operation.