Cardiopulmonary function in adult patients late after Fontan repair

The utility of novel STE parameters in echocardiographic assessment of single ventricle after Fontan palliation

Background and aims of the study A functionally single ventricle (FSV) refers to a group of congenital heart defects that are not amenable for biventricular correction. The Fontan operation is utilized as surgical treatment for most of FSV patients. The evaluation of FSV function is extremely difficult due to its unique pathophysiology. This study aimed to explore the efficacy of speckle tracking echocardiography (STE) parameters measured at rest and during exercise for comprehensive assessment of univentricular heart.

METHODS

We enrolled 37 patients with a functionally single ventricle after the Fontan operation, hospitalized in the Department of Congenital Heart Defects between years 2019 and 2021.The echocardiographic stress tests were performed in the Echocardiography Laboratory of the Congenital Heart Defects Department. The study was conducted on a bicycle ergometer in a semi-recumbent position. The parameters obtained by speckle tracking echocardiography (STE): the longitudinal strain of the FSV free wall (Ɛ) and the longitudinal strain of myocardial layers: subendocardial, medial and subepicardial were analyzed. A transmural longitudinal strain gradient (TG) was calculated as the difference between longitudinal deformation of the subendocardial and subepicardial layers. Current results of cardiac magnetic resonance imaging (CMR) and cardio-pulmonary test (CPET) were also incorporated. Demographic data, past interventions, pharmacological treatment and comorbidities were extracted from medical records.

RESULTS

Ɛ at rest and during exercise were not related to the parameters of physical capacity obtained on CPET nor to the CMR results. The transmural strain gradient was dependent on physical performance parameter- peak oxygen uptake- and related to the FSV ejection fraction calculated by magnetic resonance imaging.

CONCLUSIONS

The transmural strain gradient and FSV free wall strain are readily measurable and suitable for evaluating single ventricle function. The TG is positively correlated with peak oxygen uptake during the cardiopulmonary test and with the ejection fraction derived from cardiac magnetic resonance imaging. The applicability of these findings in patients undergoing the Fontan procedure warrants further exploration.

Stress imaging in patients with a Fontan circulation: A systematic review

INTRODUCTION

The aims of this study were to provide an overview of the cardiac stress response in Fontan patients and of the use, safety and clinical value of stress imaging in Fontan patients.

METHODS

Studies evaluating cardiac function using stress imaging in Fontan patients published up until 12 December 2021 were included in this review.

RESULTS

From 1603 potential studies, 32 studies met the inclusion criteria. In total, stress imaging tests of 728 Fontan patients were included. Cardiac function was most often measured using physical stress (61%), all other studies used dobutamine-induced stress. Stroke volume (SV) increased in most studies (71%), mean SV at rest ranged from 27 mL/m2 to 60 mL/m2 versus 27 mL/m2 to 101 mL/m2 during stress, and increased with an average of 4%. Ejection fraction increased in almost all studies, whereas both end-systolic volume and end-diastolic volume decreased during stress. Higher heart rates were obtained with physical stress (82-180) compared to dobutamine induced stress (73-128). Compared to controls, increases in heartrate and SV were lower and end-diastolic volume decreased abnormally in 75% of reporting studies. No major adverse events were reported. Poorer cardiac stress response was related to decreased exercise capacity and higher risk for long-term (adverse) outcomes in Fontan patients.

DISCUSSION

Cardiac stress response in Fontan patients differs from healthy subjects, reflected by lower increases in heart rate, diminished preload and decreased cardiac output, especially during higher levels of exercise. Stress imaging is safe, however the added clinical value needs to be investigated in more detail.

Exercise Capacity and Cardiorespiratory Fitness in Children with Congenital Heart Diseases: A Proposal for an Adapted NYHA Classification

OBJECTIVE

To propose and evaluate an adapted NYHA classification for children with congenital heart disease (CHD) as a feasible clinical tool for classifying patients' fitness, cardiorespiratory efficiency and functional limitations during their ordinary daily activities, which are also characterized by vigorous and competitive physical exercise among peers.

METHODS

This cross-sectional investigation analyzed 332 patients (13.1 ± 3.01 y/o) who underwent surgical repair of CHD and performed Cardiopulmonary Exercise Testing (CPET). Patients were divided into NYHA class I, IIA and IIB by specific questioning regarding functional limitation and performance compared to peers and at strenuous intensity. Class IIA was characterized by slight exercise limitation only for strenuous/competitive activities, whereas IIB for already ordinary physical activities. These NYHA classes were compared with maximal CPET on treadmill.

RESULTS

Patients' exercise capacity (exercise time, METs), aerobic capacity (VO2peak) and chronotropic response were found progressively impaired when NYHA class I was compared with IIA and IIB. Indeed, ventilatory-perfusion mismatch (PETCO2, VE/VCO2) significantly worsened from NYHA class I to IIA, while no difference was found between IIA and IIB.

CONCLUSION

This adapted NYHA-CHD classification could allow regular functional evaluations and accurate assessments by clinicians, leading to facilitated clinical management and timely medical interventions.

Serial Cardiopulmonary Exercise Testing in Patients after Extracardiac Conduit Total Cavopulmonary Connection for Single-Ventricle Hearts: An Observational Study

OBJECTIVE

To analyze the aerobic fitness and evolution of exercise tolerance in patients with single-ventricle physiology after total cavopulmonary connection (TCPC) with an extracardiac conduit (ECC).

STUDY DESIGN

This retrospective cohort study included patients with previous ECC-TCPC who underwent cardiopulmonary exercise testing (CPET) between September 2010 and September 2019. Patients who completed at least 2 tests (≥6 months apart) with adequate levels of effort were recruited for the serial CPET evaluation.

RESULTS

We identified 70 patients (50% male) with a mean age of 6.45 ± 5.14 years at ECC-TCPC and 15.67 ± 5.03 years at the initial CPET. The peak oxygen consumption (peak VO₂) to predicted value (peak PD) was 55.90 ± 16.81%. Twenty of the 70 identified patients (50% male) were recruited for serial analysis. The average number of CPETs was 2.6 per patient. The average duration from the first CPET to the last CPET was 3.64 years. The peak VO₂ and PD increased slowly, with mean rates of 38.77 ± 129.01 mL/min and 1.66 ± 6.40%, respectively, during the study period.

CONCLUSIONS

Although the patients had lower exercise tolerance after ECC-TCPC compared with their normal peers, exercise tolerance appears to have been preserved over the adolescent period in those who underwent serial testing after ECC-TCPC.

Aerobic exercise and inspiratory muscle training increase functional capacity in patients with univentricular physiology after Fontan operation: A randomized controlled trial

BACKGROUND

The effect of exercise training and its mechanisms on the functional capacity improvement in Fontan patients (FP) are virtually unknown. This trial evaluated four-month aerobic exercise training and inspiratory muscle training on functional capacity, pulmonary function, and autonomic control in patients after Fontan operation.

METHODS

A randomized controlled clinical trial with 42 FP aged 12 to 30 years and, at least, five years of Fontan completion. Twenty-seven were referred to a four-months supervised and personalized aerobic exercise training (AET) or an inspiratory muscle training (IMT). A group of non-exercise (NET) was used as control. The effects of the exercise training in peak VO₂; pulmonary volumes and capacities, maximal inspiratory pressure (MIP); muscle sympathetic nerve activity (MSNA); forearm blood flow (FBF); handgrip strength and cross-sectional area of the thigh were analyzed.

RESULTS

The AET decreased MSNA (p = 0.042), increased FBF (p = 0.012) and handgrip strength (p = 0.017). No significant changes in autonomic control were found in IMT and NET groups. Both AET and IMT increased peak VO2, but the increase was higher in the AET group compared to IMT (23% vs. 9%). No difference was found in the NET group. IMT group showed a 58% increase in MIP (p = 0.008) in forced vital capacity (p = 0.011) and forced expiratory volume in the first second (p = 0.011). No difference in pulmonary function was found in the AET group.

CONCLUSIONS

Both aerobic exercise and inspiratory muscle training improved functional capacity. The AET group developed autonomic control, and handgrip strength, and the IMT increased inspiratory muscle strength and spirometry.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02283255.

Single ventricle systolic function and cardiopulmonary exercise performance in adult patients with Fontan circulation

OBJECTIVE

We employed echocardiographic tissue characterization for the assessment of single ventricle systolic function and examined its relationship with cardiopulmonary exercise testing (CPET) performance in the Fontan circulation.

METHODS

40 consecutive adult Fontan patients (16 female, 24 male; mean age 26.3 ± 5.9) were enrolled in our prospective cross-sectional study. All patients underwent echocardiographic assessment including tissue characterization and CPET within 3 days from each other.

RESULTS

LAPSE (lateral annular plane systolic excursion) was higher in patients with a dominant left ventricle compared to a dominant right ventricle (12.3 + -2.6 vs 9.8 + -1.1 mm, p = .008) and in patients with AP (right atrium-pulmonary artery) connection than with lateral tunnel or extracardiac conduits (13.9 ± 1.7 vs 11.3 ± 2.6 and 10.9 ± 2.2 mm, p = .014 and p = .014, respectively). Maximal oxygen pulse (O₂ pulse max) was significantly higher in patients with a dominant left or common ventricle compared to patients with a dominant right ventricle (10.3 and 12.0 vs 6.6 ml/beat, p = .002 and p = .032, respectively). There was a positive correlation between O₂ pulse max and LAPSE (r = 0.442, p = .009), atrioventricular valve annulus systolic velocity (S') (r = 0.606, p < .0001), lateral wall basal segment systolic velocity (bas vel s) (r = 0.469, p = .009) and lateral wall mid segment systolic velocity (mid vel s) (r = 0.452, p = .012). In the multivariable regression model, S' (r = 0.606, p < .0001) remained predictive of O₂ pulse max.

CONCLUSIONS

LAPSE and S' are suitable parameters for the assessment of systolic function in Fontan patients. Subclinical systolic dysfunction of longitudinal fibers is associated with worse CPET performance. O₂ pulse max seems to be the best parameter reflecting Fontan patients' physical performance.

Possible molecular and paracrine involvement underlying the pathogenesis of COVID-19 cardiovascular complications

Coronavirus disease 2019 (COVID-19) has been declared a pandemic on 11 March 2020 by the WHO. Despite being mainly a respiratory virus, cardiac complications have been described. These range from sudden cardiac death to subtle diastolic dysfunction after recovery from COVID-19. The commonest cardiac presentation to date is acute heart failure resulting from biventricular or left ventricular hypokinesis and elevation of cardiac troponins. It has been shown that COVID-19 downregulates angiotensin-converting enzyme-2, which has protective effects on the endothelium and cardiomyocytes. It has also been proven that COVID-19 induces a state of hypercytokinaemia, some cytokines such as interleukin-1 and interleukin-6 have an injurious effect on the myocardium and endothelium, respectively. Such pathogenic mechanisms might play a crucial role in induction of cardiomyocyte injury and impaired myocardial perfusion probably through coronary endothelial dysfunction. The understanding and linking of such mechanisms might help in tailoring drug repurposing for treatment or prophylaxis of COVID-19 cardiovascular complications.

Contributions of residual hypoxemia to exercise hyperventilation in Fontan patients

It is unsettled whether increased exercise ventilation in Fontan subjects is due to increased pulmonary dead space or augmented ventilatory drive. Twenty-six Fontan patients underwent symptom-limited treadmill cardiopulmonary exercise testing. Two groups of age- and sex- matched subjects served as controls: the biventricularly repaired (Bi, n = 18), and the "true" control (C, n = 29) groups. Peak oxygen uptake (V̇O_2peak) was not different among groups (41.0 +/- 8.4 ml/min/kg, 43.5 +/- 6.6 ml/min/kg, and 45.9 +/- 11.6 ml/min/kg for Fontan, Bi, and C groups, respectively, p = 0.16). Fontan subjects, however, showed steeper alveolar ventilation/carbon-dioxide (V̇A/V̇CO₂) regression slope (35.5 +/- 5.3, 28.7 +/- 3.8, and 29.5 +/- 3.0 l/ml, for Fontan, Bi, and C groups, respectively, p<0.0001), and lower end-expiratory carbon-dioxide fraction (FetCO_2VAT) at ventilatory threshold (VAT) (4.4 +/- 0.5%, 5.5 +/- 0.5%, and 5.5 +/- 0.4%, for Fontan, Bi, and C groups, respectively, p<0.001). The dead-space ventilation fraction at VAT was similar among groups (0.33 +/- 0.06, 0.33 +/- 0.04, 0.35 +/- 0.05 for Fontan, Bi, and C groups, respectively, p = 0.54). In Fontan subjects, arterial oxygen saturation at rest (SaO_2rest) was correlated with V̇A/V̇CO₂ regression slope (r = -0.41, p = 0.04) and with FetCO_2VAT (p = -0.53, p<0.01). We conclude that Fontan patients show exercise hyperventilation due to augmented central and/or peripheral ventilatory drive, which is further augmented by residual hypoxemia.

Prognostic power of cardiopulmonary exercise testing in Fontan patients: a systematic review

Objective

Exercise impairment is common in Fontan patients. Our aim is to systematically review previous literature to determine the prognostic value of exercise capacity in older adolescent and adult Fontan patients with respect to late outcome. Additionally, we reviewed the determinants of exercise capacity in Fontan patients and changes in exercise capacity over time.

Methods

PubMed, CINAHL, Embase, The Cochrane Library and Scopus were searched systematically for studies reporting exercise capacity and late outcome such as mortality, cardiac transplantation and hospitalisation. Studies were eligible for inclusion if more than 30 patients were included and mean age was ≥16 years.

Results

Four thousand and seven hundred and twenty-two studies were identified by the systematic search. Seven studies fulfilled the inclusion and exclusion criteria. The total number of patients was 1664 adult Fontan patients. There were 149 deaths and 35 heart transplantations. All eligible studies were retrospective cohort studies. The correlation between exercise capacity and late outcome was identified, and HRs were reported.

Conclusion

In Fontan patients, the best predictors of death and transplantation were a decline in peak VO₂, heart rate variables and exercise oscillatory ventilation. Peak VO₂ was not strongly predictive of mortality or hospitalisation in Fontan patients. Several variables were strong and independent predictors of hospitalisation and morbidity.

Exercise performance after univentricular palliation

Background:

The optimal timing, need for primary/staged procedure in patients undergoing univentricular palliation, is debatable.

Aims:

We performed this study to assess the exercise performance of patients undergoing various forms of univentricular palliation.

Setting and Design:

This was a retrospective, prospective comparative study conducted at a multispecialty tertiary referral center.

Patients and Methods:

Between January 2012 and June 2015, 117 patients undergoing either bidirectional Glenn (BDG) (n = 43) or Fontan (total cavopulmonary connection [TCPC]) (n = 74) underwent exercise testing.

Statistical Analysis:

Comparisons between subgroups for continuous data were made with Student's t-test if normally distributed and Wilcoxon rank-sum test otherwise. Tests between subgroups for qualitative data were made with Pearson's Chi-square test.

Results:

Patients who underwent BDG with open antegrade pulmonary blood flow (APBF) had higher saturations (oxygen saturation [SpO₂]) compared to those without it (87.5 ± 5.0% vs. 81.1 ± 4.8%; P = 0.0001). However, we found no differences in exercise parameters of patients undergoing BDG with or without APBF. Extracardiac TCPC (n = 42) patients demonstrated better exercise capacity (15.0 ± 7.7 vs. 11.2 ± 6.2 min; P = 0.02) and increased SpO₂ on exercise (87.0 ± 8.0% vs. 83.4 ± 7.6%; P ≤ 0.05) compared to lateral tunnel TCPC (n = 32). Fenestrated TCPC (n = 30) patients had higher exercise capacity reflected by higher metabolic equivalents (METs) consumption (6.4 ± 2.3 vs. 5.2 ± 2.0 METs, P = 0.02), fewer pleural effusions (7.0 ± 3.2 vs. 9.2 ± 6.2 days, P ≤ 0.05), and lower hospital stay (9.5 ± 4.0 vs. 12.7 ± 7.7 days, P = 0.04) compared to nonfenestrated TCPC (n = 44) patients.

Conclusions:

We observed no differences in exercise parameters of patients undergoing BDG with or without APBF. Extracardiac TCPC patients had better exercise capacity but longer postoperative hospital stay and pleural effusions than patients with lateral tunnel Fontan. Fenestrated TCPC patients seemed to fare better than nonfenestrated ones. Patients undergoing TCPC had better exercise capacity than patients undergoing BDG alone.

Relationship Between Habitual Exercise and Performance on Cardiopulmonary Exercise Testing Differs Between Children With Single and Biventricular Circulations

Increasing habitual exercise has been associated with improved cardiopulmonary exercise testing (CPET) performance, specifically maximal oxygen consumption in children with operatively corrected congenital heart disease. This has not been studied in children following Fontan palliation, a population in whom CPET performance is dramatically diminished. A single-center cross-sectional study with prospective and retrospective data collection was performed that assessed habitual exercise preceding a clinically indicated CPET in children and adolescents with Fontan palliation, transposition of the great arteries following arterial switch operation (TGA), and normal cardiac anatomy without prior operation. Data from contemporaneous clinical reports and imaging studies were collected. The association between percent predicted VO_2max and habitual exercise duration adjusted for known covariates was tested. A total of 175 subjects (75 post-Fontan, 20 with TGA, and 80 with normal cardiac anatomy) were enrolled. VO_2max was lower in the Fontan group than patients with normal cardiac anatomy (p < 0.0001) or TGA (p < 0.0001). In Fontan subjects, both univariate and multivariate analysis failed to demonstrate a significant association between habitual exercise and VO_2max (p = 0.6), in sharp contrast to cardiac normal subjects. In multivariate analysis, increasing age was the only independent risk factor associated with decreasing VO_2max in the Fontan group (p = 0.003). Habitual exercise was not associated with VO_2max in subjects with a Fontan as compared to biventricular circulation. Further research is necessary to understand why their habitual exercise is ineffective and/or what aspects of the Fontan circulation disrupt this association.

The Long-Term Management of Children and Adults with a Fontan Circulation: A Systematic Review and Survey of Current Practice in Australia and New Zealand

Although long-term survival is now the norm, Fontan patients face significant morbidity and premature mortality. Wide variation exists in long-term Fontan management. With an aim of improving their long-term management, we conducted a systematic review to identify best available evidence and gaps in knowledge for future research focus. We also surveyed cardiologists in Australia and New Zealand managing Fontan patients, to determine the alignment of current local practice with best available evidence. A systematic review was conducted using strict search criteria (PRISMA guidelines), pertaining to long-term Fontan management. All adult congenital and paediatric cardiologists registered with The Australia and New Zealand Fontan Registry were invited to respond to an online survey. Reasonable quality evidence exists for non-inferiority of aspirin over warfarin for thromboprophylaxis in standard-risk Fontan patients. No strong evidence is currently available for the routine use of ACE inhibitors, beta blockers or pulmonary vasodilators. Little evidence exists regarding optimal arrhythmia treatment, exercise restriction/prescription, routine fenestration closure, elective Fontan conversion and screening/management of liver abnormalities. Although pregnancy is generally well tolerated, there are high rates of miscarriage and premature delivery. Thirty-nine out of 78 (50 %) cardiologists responded to the survey. Heterogeneity in response was demonstrated with regard to long-term anti-coagulation, other medication use, fenestration closure and pregnancy and contraception counselling. Substantial gaps in our knowledge remain with regard to the long-term management of Fontan patients. This is reflected in the survey of cardiologists managing these patients. We have identified a number of key areas for future research.

Clinical Profile and Quality of Life of Adult Patients After the Fontan Procedure

Increasingly, more patients with univentricular heart reach adulthood. Therefore, long-term psychological features are an important concern. The aim of this study was to evaluate the clinical and psychological profile of post-Fontan adult patients and to identify the most significant determinants of quality of life. In this retrospective cross-sectional study, we reviewed the surgical and medical history of post-Fontan adult patients. Patients underwent a 24-h electrocardiogram, echocardiography and exercise testing. Self-report questionnaires were used to assess the Work Ability Index, quality of life (Satisfaction with Life Scale), perceived health status (SF-36 questionnaire), coping strategies (Brief Cope questionnaire) and presence of mood disorders (Hospital Anxiety and Depression Scale). Thirty-nine patients aged between 18 and 48 years (mean 27.5 years) were enrolled. The mean follow-up was 21.5 years. Most patients were unmarried (82.9 %), had a high school diploma (62.9 %) and were employed (62.9 %). Twenty-nine patients (82.3 %) had at least one long-term complication. The median single ventricle ejection fraction was 57 %, and the median maximal oxygen consumption was 26.8 ml/min/kg. This population tended to be anxious and to use adaptive coping strategies. Quality of life was perceived as excellent or good in 57.2 % of cases and was not related to either cardiac function or exercise capacity. Both quality of life and SF-36 domains were related to the Work Ability Index. This cohort of post-Fontan adult patients enjoyed a good quality of life irrespective of disease severity.

Older Age at Completion of Fontan Procedure Is Associated with Improved Percentage of Predicted Maximum Oxygen Uptake

We tested the hypothesis that later completion of the Fontan procedure is associated with improved exercise capacity in the current period of staged single-ventricle palliation. We performed a retrospective study, in Fontan patients, of exercise stress test data from April 2003 through March 2011. Patients were included if they had received staged palliations in accordance with current surgical strategy, defined as the performance of a superior cavopulmonary connection at ≤1 year of age, followed in subsequent years by Fontan completion. Patients with a pacemaker or respiratory exchange ratio <1 were excluded. Early and late Fontan groups were created on the basis of whether Fontan completion had been performed at <4 or ≥ 4 years of age. The primary predictor variable was age at Fontan completion, and the primary marker of exercise performance was the percentage of predicted maximum oxygen consumption. During the study period, 55 patients were identified (mean age, 11.7 ± 2.8 yr). Older age at Fontan completion correlated positively with higher percentages of predicted maximum oxygen consumption (R=0.286, P=0.034). Patients in whom Fontan completion was performed at ≥4 years of age had higher percentages of predicted maximum oxygen consumption than did those in whom completion was at <4 years of age (84.4 ± 21.5 vs 72.9 ± 18.1; P=0.041). Later Fontan completion might be associated with improved exercise capacity in patients palliated in accordance with contemporary surgical strategy.

Should We Recommend Exercise after the Fontan Procedure?

BACKGROUND

The Fontan procedure, the last of a series of operations performed in patients with congenital heart defects, offers improved exercise capacity compared to baseline function but is still reduced compared to healthy peers. Exercise training may improve exercise tolerance but there is no consensus on the safety of this practice or the optimal training regimen. We performed a systematic literature review on the effects of exercise training in patients with a Fontan circulation.

METHODS

Medline and Embase databases were systematically searched for articles regarding Fontan Procedure and cardiac rehabilitation.

RESULTS

A total of 23 articles met all inclusion criteria; in total, 201 Fontan subjects were included. Characteristics of the exercise training programs varied significantly. There were no adverse effects related to training programs reported in the literature. Most studies reported benefit across various exercise parameters related to exercise tolerance.

CONCLUSIONS

Exercise training is safe and beneficial in patients with a Fontan circulation. Exercise training should become a standard of care within this population. Physiological adaptation following exercise training needs to be investigated more extensively.

Anesthetic Management of Parturients With a Fontan Circulation

Parturients with Fontan physiology provide unique and complex challenges to anesthesiologists. Such challenges include the maintenance of a perfect balance between preload, pulmonary vascular resistance, afterload, and cardiac output in a setting of a single ventricle physiology. The physiological changes of pregnancy add additional burden to an already “fragile” physiology, making the anesthetic management for labor and/or cesarean delivery even more complex. Understanding the impact of these changes on the Fontan physiology and the effect of anesthetic choices on this dyad (pregnancy–Fontan) is an imperative prior to caring for these patients. In an effort to determine how these patients are best managed for labor and/or cesarean delivery, we have reviewed the literature examining the peripartum anesthetic management of parturients with Fontan circulation and have identified 27 case reports.

Hemodynamic performance of the Fontan circulation compared with a normal biventricular circulation: a computational model study

The physiological limitations of the Fontan circulation have been extensively addressed in the literature. Many studies emphasized the importance of pulmonary vascular resistance in determining cardiac output (CO) but gave little attention to other cardiovascular properties that may play considerable roles as well. The present study was aimed to systemically investigate the effects of various cardiovascular properties on clinically relevant hemodynamic variables (e.g., CO and central venous pressure). To this aim, a computational modeling method was employed. The constructed models provided a useful tool for quantifying the hemodynamic effects of any cardiovascular property of interest by varying the corresponding model parameters in model-based simulations. Herein, the Fontan circulation was studied compared with a normal biventricular circulation so as to highlight the unique characteristics of the Fontan circulation. Based on a series of numerical experiments, it was found that 1) pulmonary vascular resistance, ventricular diastolic function, and systemic vascular compliance play a major role, while heart rate, ventricular contractility, and systemic vascular resistance play a secondary role in the regulation of CO in the Fontan circulation; 2) CO is nonlinearly related to any single cardiovascular property, with their relationship being simultaneously influenced by other cardiovascular properties; and 3) the stability of central venous pressure is significantly reduced in the Fontan circulation. The findings suggest that the hemodynamic performance of the Fontan circulation is codetermined by various cardiovascular properties and hence a full understanding of patient-specific cardiovascular conditions is necessary to optimize the treatment of Fontan patients.

Effect of Fontan fenestration on regional venous oxygen saturation during exercise: further insights into Fontan fenestration closure

Fontan fenestration closure is a topic of great debate. The body of data regarding the risks and benefits of fenestration closure is limited yet growing. Previous studies have demonstrated that Fontan patients have less exercise capacity than those with normal cardiovascular anatomy. Differences also have been noted within various subgroups of Fontan patients such as whether Fontan is fenestrated or not. This study aimed to compare trends in regional oxygen saturations using near-infrared spectroscopy (NIRS) in patients with Fontan circulations during ramping exercise to further delineate differences between patients with and without a fenestration. It was hypothesized that Fontan patients with fenestrations have better exercise times, higher absolute regional oxygen venous saturations, and smaller arteriovenous differences than Fontan patients without fenestrations. For this study, 50 consecutive Fontan patients and 51 consecutive patients with normal cardiovascular anatomy were recruited. Placement of NIRS probes was performed to obtain regional oxygen saturations from the brain and the kidney. Readings were obtained at 1-min intervals during rest, exercise, and recovery. A standard Bruce protocol was used with a 5-min recovery period. Absolute regional tissue oxygenation values (rSO2) and arterial-venous oxygen saturation differences (AVDO2) calculated as arterial oxygen saturation (SPO2)--rSO2 for normal versus Fontan patients and for fenestrated versus unfenestrated Fontan patients were compared using independent t tests. When normal and Fontan patients were compared, the Fontan patients had a significantly shorter duration of exercise (9.3 vs 13.2 min; p < 0.001). No statistically significant difference in rSO2 change or AVDO2 was evident at the time of peak exercise, at 2 min into the recovery, or at 5 min into the recovery. A small oxygen debt also was paid back to the brain in the Fontan patients after exercise, as evidenced by a narrower AVDO2 than at baseline. The comparison of Fontan patients with and without fenestration showed no statistically significant difference in exercise time, rSO2 change, or AVDO2. The Fontan patients were noted to have shorter exercise times than the normal patients and also appeared to have an alteration in postexertional regional blood flow. However, when the various Fontan subtypes were compared by presence or absence of a fenestration, no significant differences were noted with regard to change in regional oxygen saturation or arteriovenous oxygen saturation. Thus, for patients with Fontan physiology, closure of the fenestration does not seem to have an impact on the dynamics of regional oxygen extraction during exercise or recovery.

Exercise capacity in the Fontan circulation

The Fontan operation can create a stable circulation from childhood through early adulthood. However, the absence of a sub-pulmonary pumping chamber leads to a physiology in which exercise capacity is limited and decreases with age starting in adolescence. The limitation in exercise capacity is more pronounced at peak levels of exercise, but is still present during more modest levels of activity. The underlying causes of exercise impairment relate to both central cardiovascular factors (oxygen delivery) and peripheral factors (oxygen extraction). Interventions to improve cardiac preload and to improve lean muscle mass may help to improve exercise capacity and, perhaps, will alter the "natural history" of the progressive decline.

Habitual exercise correlates with exercise performance in patients with conotruncal abnormalities

Cardiopulmonary exercise testing (CPET), particularly maximal oxygen consumption (VO2max), has been used to assess the outcome for patients with palliated congenital heart disease (CHD). Small studies correlating VO2max with noninvasive imaging measures of ventricular function have led to the hypothesis that VO2max reflects cardiac performance. In other settings, physical training is associated with increased VO2max. The authors hypothesized that habitual exercise correlates with VO2max to a greater degree than ventricular function in a relatively healthy cohort of patients with palliated CHD. The habitual exercise behavior of 208 subjects with conotruncal abnormalities (tetralogy of Fallot, truncus arteriosus, and interrupted aortic arch) at the time of previously performed, study-based CPET and cardiac magnetic resonance imaging (CMR) were retrospectively assessed via questionnaire. The association of VO2max with habitual exercise duration and CMR measures of ventricular function was tested. Of 208 subjects, 89 (43 %) completed questionnaires, and 78 % of the 89 patients had a concurrent CMR. The mean VO2max was 76 ± 21 % of that predicted. The CMR-assessed left ventricular ejection fraction was 67.6 ± 7.4 %. The hours of habitual exercise per week correlated with VO2max (p < 0.001; r (2) = 0.14). No association was found between right and left ventricular ejection fraction, cardiac index, or right ventricular end-diastolic volume and VO2max. In this study, VO2max correlated with habitual exercise to a greater degree than CMR measurements of ventricular function. These findings highlight the importance of considering the contribution of noncardiac factors when exercise data in both clinical and research settings are interpreted. The contribution of these factors to clinical outcomes deserves further study.

Long-term results of total cavopulmonary connection with low ejection fraction

PURPOSE

The aim of this study was to investigate the surgical outcomes and change in cardiac performance after total cavopulmonary connection (TCPC) in patients with reduced ventricular ejection preoperatively.

METHODS

Among the 195 patients undergoing TCPC between 1990 and 2001 were 52 who had a preoperative ejection fraction of ≤50% (30%-50%, mean 44%). A dominant ventricle was of the morphologically right type in 81% of patients.

RESULTS

A total of 9 of the 52 patients died early. Two patients died in the intermediate term. Postoperative exercise testing showed maximum oxygen uptake of 26.4 ± 5.8 ml/kg/min (anaerobic threshold 18.3 ± 3.2 ml/kg/ min). The cardiac index was 3.1 ± 0.9 l/min/m(2) at 1 year after TCPC, with no fundamental change at 5 years (3.1 ± 0.8 l/min/m(2)). The end-diastolic volume of the dominant ventricle was 130% ± 74% of the anticipated normal value at 1 year and 93% ± 27% at 5 years after TCPC, with ejection fractions of 48% ± 13% and 49% ± 9%, respectively. When these parameters were plotted for the individual patients, the ejection fraction increased during the first postoperative year, with the percent end-diastolic volume decreasing in 31 survivors; the trend appeared atypical in the remaining 12 survivors. Even in these patients, however, the parameters eventually changed toward favorable circumstances 5 years after TCPC.

CONCLUSION

Change in ventricular function was not necessarily pessimistic after TCPC in patients with reduced ventricular contraction preoperatively.

Cerebral hemodynamics in the presence of decreased systemic venous compliance in patients with Fontan physiology may limit anaerobic exercise capacity

Patients who have had the Fontan procedure report poor exercise performance. Fontan subjects can tolerate a higher level of sub maximal activity than might be anticipated from VO2, suggesting a different mechanism of exercise limitation. Near-infrared spectroscopy (NIRS) provides a non-invasive, continuous method to monitor regional tissue oxygenation (rSO2) and thereby a window into regional oxygen supply-demand relationships. We hypothesized that Fontan patients would have altered rSO2 trends from normal population that might reflect the mechanisms of exercise limitation. All the patients without structural or acquired heart disease and Fontan patients were eligible for inclusion if they were ordered to undergo cardiopulmonary exercise testing (CPET). Four-site regional rSO2 were recorded continuously during exercise. The difference between the oxyhemoglobin saturation measured by pulse oximetry (SpO2) and NIRS (rSO2) was computed as the regional arterial-venous saturation difference (AVDO2). A total of 33 normal subjects and five Fontan subjects scheduled for CPET were recruited. None of the Fontan subjects had a fenestration of the conduit. In the cerebral circulation, the Fontan patients have a significantly higher initial slope of increasing AVDO2 compared with normals. After vAT, the AVDO2 slope is flat for Fontan patients (p = 0.02). There is also a substantially larger rebound of cerebral rSO2 than in normal subjects after QT (p < 0.0001). Reduced anaerobic exercise capacity in Fontan patients may be secondary to limitation of cerebral blood flow, secondary to low systemic venous compliance due to absence of a sub-pulmonary ventricle, and augmented hyperventilatory response during exercise.

Serial cardiopulmonary exercise testing in patients with previous Fontan surgery

Patients with previous Fontan surgery have reduced peak oxygen consumption (Vo 2), and data regarding progression of exercise intolerance is limited. The purpose of this study was to assess the evolution of exercise tolerance in patients with previous Fontan surgery. We performed a retrospective cohort study of patients with previous Fontan surgery who underwent cardiopulmonary exercise testing between November 2002 and January 2009. Patients were required to have completed at least two tests, with adequate levels of effort, >or-6 months apart. We identified 78 patients (55% male) who had undergone a total of 215 cardiopulmonary exercise tests. Age at initial study was 19.7 +/- 10.2 years; time interval since previous Fontan surgery 13.3 +/- 5.7 years; and time interval between the initial and the most recent exercise test was 3.0 +/- 1.4 years. Morphologic left ventricle was present in 58 (74.4%) patients. At baseline, peak Vo 2 averaged 24.7 +/- 7.0 ml/kg/min (63.7% +/- 15.8% predicted). At most recent study, peak Vo 2 averaged 23.2 +/- 7.2 ml/kg/min, (60.4% +/- 13.9% predicted). Percent predicted peak Vo 2 declined slowly, with a mean rate of decline of 1.25 +/- 0.36 percentage points/y (p < 0.001). Most of the decline occurred in patients < 18 years of age (mean rate of decline 1.78 +/- 0.46 percentage points/y; p = 0.0004). Thereafter, the rate of decline was less marked (mean rate of decline 0.54 +/- 0.57 percentage points/y; p = not significant). Ventricular morphology, type of Fontan procedure, and cardiac medications were not predictive of progressive exercise intolerance. In conclusion, although the exercise function of previous Fontan patients tends to decline during late adolescence, it appears to stabilize during early adulthood.

Functional health status of adolescents after the Fontan procedure -- comparison with their siblings

BACKGROUND

Studies have suggested that patients who have undergone the Fontan procedure experience lower functional health status and diminished exercise capacity compared with other children.

OBJECTIVES

To compare the functional health status of Fontan patients with and without siblings, assess whether there are any differences between Fontan patients and their siblings, and determine associated factors.

METHODS

A cross-sectional, single-centre, observational study was performed on Fontan patients 10 to 20 years of age, and their sibling closest in age, followed in a tertiary pediatric hospital. Functional health status was measured by the Child Health Questionnaire Child Form and the Pediatric Quality of Life Inventory.

RESULTS

A total of 68 patients and 38 siblings were enrolled. Patients with siblings scored significantly lower on numerous domains of physical functional status than those without siblings. Compared with their matched siblings, Fontan patients reported significantly lower scores in all domains of the Pediatric Quality of Life Inventory and on physical (but not psychosocial) domains of the Child Health Questionnaire Child Form. Factors associated with increased patient-sibling differences included younger patient age, female sex, intracardiac lateral tunnel Fontan connection and lower ejection fraction at the time of study enrollment.

CONCLUSIONS

Adolescents with Fontan physiology reported a lower functional health status in physical domains than their siblings, but had similar status in psychosocial domains. Having a sibling was associated with lower reported functional health status, suggesting an important effect of self-perceived physical limitations over true limitations.

Exercise capacity reflects ventricular function in patients having the Fontan circulation

BACKGROUND

In this study we sought to determine, first, whether maximal exercise capacity reflects ventricular function, and second, whether the age of the patient, and the age of completion of the Fontan circulation, influence ventricular function and exercise performance.

METHODS AND RESULTS

Cardiac magnetic resonance imaging and cardiopulmonary exercise testing were performed in 29 patients at a median time of 6.9 years after completion of the Fontan circulation. We divided the patients into 2 groups, the first 19 having their operation below the age of 18 years, and the second group, of 10 patients, having completion of the Fontan circulation when they were older than 18 years. Parameters for ventricular function and exercise were compared for both groups with controls. Compared to controls, the younger patients had normal end-diastolic ventricular volumes, but significantly impaired ventricular function, lower maximal work load and consumption of oxygen. The older patients had greater end-diastolic ventricular volumes, and significantly poorer ventricular function than both the younger patients and the controls. Maximal work load and consumption of oxygen were significantly lower in the older patients than in the younger ones and the controls.

CONCLUSION

Patients with the Fontan circulation have an impaired systolic ventricular function, which correlates with maximal exercise capacity and uptake of oxygen. Those having completion of the Fontan circulation when younger than 18 years had significantly better ventricular function and exercise performance than those who had completion of the Fontan circulation at an older age. An early creation of the Fontan circulation may preserve cardiac function and exercise capacity.

Exercise performance after surgery for pulmonary atresia and intact ventricular septum

The objective of this study was to assess exercise performance in subjects born in Sweden between 1980 and 1995 and undergoing surgery for pulmonary atresia and intact ventricular septum and to identify determinants of exercise performance. Twenty-seven subjects, 16 with biventricular repair and 11 with univentricular palliation, and 28 age- and sex-matched controls completed cardiopulmonary exercise and lung function testing. Peak oxygen uptake was determined using a symptom-limited ramp bicycle exercise protocol. Regression analysis was performed to identify predictors of peak oxygen uptake (V'O(2)), The index group had lower peak V'O(2) (1.4 [median 0.8; range 2.5] l/min) than controls (1.9 [0.7; 3.1]; p < 0.05). Subjects without ventriculocoronary arterial communications (VCAC), corrected to biventricular circulation, had higher peak V'O(2), than the remaining index subjects. Decreased total lung capacity, low minute ventilation, and high physiologic dead space measured at peak exercise were all independent determinants of low peak V'O(2) Exercise capacity is generally decreased in subjects with pulmonary atresia and intact ventricular septum, although there are marked interindividual differences. Good exercise capacity was found in subjects without VCAC who had undergone biventricular repair. Decreased lung function was an unfavourable predictor of exercise capacity.

Exercise function of children with congenital aortic stenosis following aortic valvuloplasty during early infancy

OBJECTIVES

The objectives of this study were to characterize the exercise function of patients treated with balloon aortic valvuloplasty at

BACKGROUND

Balloon aortic valvuloplasty is the primary therapy for neonatal aortic stenosis (AS). Residual and/or acquired abnormalities of left heart structure and function may adversely affect exercise capacity. Methods. We prospectively recruited patients >6 years old with a history of neonatal AS to undergo exercise testing.

RESULTS

We enrolled 30 patients (median age 13.1 years) who underwent balloon aortic valvuloplasty at a median age of 12 days. At time of exercise testing, the median maximum Doppler AS gradient was 34 mm Hg (0-70 mm Hg); 11 patients had moderate or severe aortic regurgitation. All patients were asymptomatic. Overall, peak oxygen consumption (VO(2)) was below normal (87 +/- 18% predicted; P < .001), and was severely depressed (

CONCLUSION

Although exercise function is preserved in most patients with a history of AS treated in early infancy, a subset have markedly reduced peak VO(2), usually because of inability to increase stroke volume.

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Key Words

• aortic stenosis
• exercise
• balloon aortic valvuloplasty

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MESH Headings

• Adolescent
• Aortic Valve/physiology
• Aortic Valve/surgery
• Aortic Valve Stenosis/congenital
• Aortic Valve Stenosis/physiopathology
• Aortic Valve Stenosis/surgery
• Catheterization
• Child
• Exercise
• Exercise Test
• Female
• Follow-Up Studies
• Heart Rate/physiology
• Humans
• Infant
• Infant, Newborn
• Male
• Oxygen Consumption/physiology
• Predictive Value of Tests
• Prospective Studies
• Stroke Volume/physiology
• Young Adult

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Grants

• T32 HL007572 NHLBI NIH HHS

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Affiliation(s)

Alaina K Kipps Department of Cardiology, Children's Hospital, Boston, Mass 02115, USA.
Doff B McElhinney
Janet Kane
Jonathan Rhodes

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Factors associated with adverse neurodevelopmental outcomes in infants with congenital heart disease

OBJECTIVE

To review reported neurodevelopmental outcome data for patients with congenital heart disease, identify risk factors for adverse neurodevelopmental sequelae and summarize potential neuromonitoring strategies that have been described.

METHODS

A Medline search was performed utilizing combinations of the keywords congenital heart, cardiac, neurologic, neurodevelopment, neuromonitoring, quality of life, and outcome. All prospective and longitudinal follow-up studies of patients with congenital heart disease were included. Additionally, studies that examined neuroimaging, neuromonitoring, and clinical factors in relation to outcome were examined. Case reports and editorials were excluded. Additional references were retrieved from selected articles if the abstract described an evaluation of neurodevelopmental outcomes and/or predictors of outcome in patients with congenital heart disease.

RESULTS

Overall, patients with CHD have increased rates of neurodevelopmental impairments, although intelligence appears to be in the normal range. Preoperative risk stratification, intraoperative techniques, postoperative care, and neuromonitoring strategies may all contribute to ultimate long-term neurodevelopmental outcomes in patients with CHD postsurgical repair.

CONCLUSIONS

As advances in the medical and surgical management improves survival in patients with CHD, increasing knowledge about neurodevelopmental outcomes and the factors that affect them will provide for strategies to optimize long-term outcome in this high-risk population.

An integrated approach to the care of adult patients with prior atriopulmonary Fontan surgery

Because of improved survival among children born with heart disease, more adults than children are now living with congenital heart defects, providing a new challenge for ongoing evaluation and care. At Children's Memorial Hospital in Chicago, we have gained extensive expertise in the long-term outcome of patients with repaired single ventricle anatomy, particularly with regard to arrhythmias and impaired hemodynamics, and have developed an integrated approach to their care. This article will summarize (a) single ventricle physiology, (b) evolution of the Fontan operation and the long-term multi-system sequelae, (c) treatment options for patients with prior Fontan surgery, focusing on Fontan conversion with arrhythmia surgery, and (d) unique management of adult patients with prior Fontan surgery. For the foreseeable future, pediatric nurse practitioners will have an important role, including coordination of care and providing continuity in the care of adults with prior Fontan surgery.

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.

Exercise limitation in patients with Fontan circulation: a review

The aim of the current literature study was to perform a literature review of the factors contributing to exercise limitation and physiological response to exercise in patients with Fontan circulation. In patients with Fontan circulation, peak oxygen uptake ranged from about 14.4 to 32.3 ml/min/kg, and showed a slowed acceleration in the kinetics of oxygen uptake at the onset of exercise. Peak heart rate during exercise was decreased to an average of 153 +/- 10 bpm and arterial oxygen saturation was also decreased at peak exercise, with an average of 89.5 +/- 1.94%. Cardiac output was subnormal, owing to reduced stroke volume, heart rate response and affected pulmonary venous return. Ventilatory anaerobic threshold was below normal values. Moreover, the ventilatory equivalent for carbon dioxide was found to be higher. Patients with Fontan circulation possess a unique physiological response to exercise. Although there is a wide range in exercise capacity among patients, all patients have reduced tolerance to exercise. Cardiac, pulmonary, and muscular factors might play a role in reduced exercise capacity and this distinct response to exercise.

Indications for Heart Transplantation in Pediatric Heart Disease

Background— Since the initial utilization of heart transplantation as therapy for end-stage pediatric heart disease, improvements have occurred in outcomes with heart transplantation and surgical therapies for congenital heart disease along with the application of medical therapies to pediatric heart failure that have improved outcomes in adults. These events justify a reevaluation of the indications for heart transplantation in congenital heart disease and other causes of pediatric heart failure.

Methods and Results— A working group was commissioned to review accumulated experience with pediatric heart transplantation and its use in patients with unrepaired and/or previously repaired or palliated congenital heart disease (children and adults), in patients with pediatric cardiomyopathies, and in pediatric patients with prior heart transplantation. Evidence-based guidelines for the indications for heart transplantation or retransplantation for these conditions were developed.

Conclusions— This evaluation has led to the development and refinement of indications for heart transplantation for patients with congenital heart disease and pediatric cardiomyopathies in addition to indications for pediatric heart retransplantation.

Health-related quality of life: A closer look at related research in patients who have undergone the Fontan operation over the last decade

The advancements in surgical technique and perioperative care have significantly improved the survival of children with single ventricle (SV) congenital heart disease (CHD) over the past decade. The population who have undergone the Fontan operation are growing into adulthood and facing many unique challenges. Past research has focused on functional and neurodevelopmental outcomes with inferences made to health-related quality of life (HRQOL). With the population who have undergone the Fontan operation surviving into adulthood, little research has been directed toward the self-report of HRQOL in adolescents and young adults after surgical palliation. Questions still remain on how these patients will transition into adulthood and whether they will live normal productive lives. This article reviews the literature related to HRQOL in the SV subgroup of CHD. In addition, an overview of newly developed disease-specific HRQOL instruments is presented as well as limitations and future research in HRQOL of the SV Fontan population.

Exercise Intolerance in Adults with Congenital Heart Disease

This article describes the ways to assess exercise capacity in adults with congenital heart disease (ACHD) and the impact of exercise intolerance in the population. It also discusses the likely pathogenesis of exercise intolerance in ACHD, the similarities between ACHD and acquired heart failure, and potential therapeutic options.