Restrictive Ventilatory Impairment and Arterial Oxygenation Characterize Rest and Exercise Ventilation in Patients After Fontan Operation

The objective of this study was evaluate the relationships between abnormal pulmonary circulation, lung function, and respiratory response during exercise in Fontan patients. Pulmonary function and cardiopulmonary exercise tests were performed in 101 Fontan patients and 122 controls. A small vital capacity (VC) with a high residual volume-to-total lung capacity ratio and a slight but significant low arterial saturation with hypocapnia were observed in Fontan patients. The number of surgical procedures determined VC. Total cavopulmonary connection, fenestration, higher pulmonary arterial wedge pressure, and smaller VC were independent determinants of low arterial saturation, which was the only determinant of hypocapnia. Arterial saturation decreased during exercise and resting arterial saturation correlated with that at peak exercise. Improvement in dead space ventilation was less in Fontan patients and was independently determined by resting arterial saturation. A steeper minute ventilation–carbon dioxide production slope was determined by resting arterial saturation, arterial carbon dioxide tension, and peak oxygen uptake. In Fontan patients, in addition to dead space ventilation, surgery-related reduced VC, the type of repair, and high pulmonary arterial wedge pressure cause arterial desaturation with subsequent hypocapnia, resulting in accelerated inefficient ventilation at rest and during exercise.     

Exercise and physical activity in children with cystic fibrosis

Regular exercise and habitual physical activity are important for patients with cystic fibrosis (CF). Research has demonstrated the benefits of aerobic, anaerobic, and strength exercise training programs for health and quality of life, however, the CF patient is faced with unique barriers and challenges to participation. Recently, increased levels of habitual physical activity have been shown to slow the decline in lung function in patients with CF, and regular participation in a variety of activities may result in greater adherence in the long term. Research is now available to justify the incorporation of exercise into the routine care of patients with CF. This paper provides the background and rationale for the implementation of exercise and habitual physical activity recommendations by the health care team. Education of health care providers regarding the importance of exercise and habitual physical activity for patients with CF is needed in order for exercise and physical activity to be incorporated as key components of clinical practice and into the lives of patients with CF.     

Physical activity levels in children and adolescents are reduced after the Fontan procedure, independent of exercise capacity, and are associated with lower perceived general health

Objectives

To determine physical activity levels in paediatric patients who underwent the Fontan procedure, and their relationship to functional status and exercise capacity.

Study Design

We studied 147 patients (ages 7–18 years) at a median of 8.1 years after Fontan, as part of the Pediatric Heart Network cross‐sectional study of Fontan survivors. Assessment included medical history, self‐reported physical activity, parent‐completed Child Health Questionnaire (CHQ), cardiopulmonary exercise testing and physical activity level measured by accelerometry (MTI Actigraph).

Results

Measured time spent in moderate and vigorous activity was markedly below normal at all ages, particularly in females, and was not significantly related to self‐reported activity levels, or to maximum Vo₂, Vo₂ at anaerobic threshold or maximum work rate on exercise testing. Lower measured activity levels were significantly related to lower perceived general health but not to self‐esteem, physical functioning, social impact of physical limitations or overall physical or psychosocial health summary scores. Reduced exercise capacity was more strongly related than measured activity levels to lower scores in general health, self‐esteem and physical functioning.

Conclusions

Physical activity levels are reduced after Fontan, independent of exercise capacity, and are associated with lower perceived general health but not other aspects of functional status.     

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 Vo ₂, 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 (Spo ₂) 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.     

Maximal hemodynamic response after the Fontan procedure: Doppler evaluation during the treadmill test

Summary After undergoing the Fontan procedure for congenital heart disease, 16 young patients performed a maximal treadmill test according to the Bruce protocol. The peak velocity of the blood flow in the ascending aorta, stroke index, and cardiac index were measured by continuous-wave Doppler echocardiography at rest and at each stage of the test. The results were compared with those from 18 normal children. The body surface area was similar in the two groups. The endurance time was 37% shorter in the Fontan group than in the control group. From the beginning of exercise until the sixth minute, the increase in stroke index was lower in the Fontan group (NS). After that point, the stroke index was maintained at a high level in the control group but decreased toward its original level in the Fontan group. The response of cardiac index to exercise in the two groups was comparable until the sixth minute, after which the Fontan group failed to maintain an ascending curve. All the hemodynamic values were significantly higher in the control group at maximal exercise; at this point the cardiac index had increased 79% in the Fontan group and 170% in the control group. The subnormal response of the stroke volume at submaximal exercise and the subsequent decrease at maximal exercise following the Fontan procedure are important hemodynamic findings.     

Lung function and exercise capacity in survivors of childhood leukaemia

The survival from acute lymphoblastic leukaemia in childhood is now approximately 60–70%, and from acute myeloid leukaemia, up to 50%. However, there is little information on the effects of intensive chemotherapy and radiotherapy used in the treatment of these conditions on lung function and exercise capacity in the long term. Seventy survivors of acute leukaemia from one centre in the UK were studied. Measurements of lung volumes, spirometry and transfer factor were made. Each child also performed a standard, symptom-limited maximal exercise test on a cycle ergometer. Predictive equations for indices of lung function and exercise tolerance were calculated from 146 age- and sex-matched control subjects. The results of the survivors of leukaemia were compared to these. There was a significant reduction of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), total lung capacity (TLC), and transfer for carbon monoxide (DLCO; P < 0.05 for each measurement), in the survivors of leukaemia when compared to the control subjects. In addition, there was a mild but significant reduction of both maximal and submaximal indices of exercise capacity in the leukaemic group. A multivariate analysis was carried out to identify those variables acting independently to reduce lung volumes. For FEV1, FVC and TLC, these were craniospinal irradiation, cyclophosphamide and chest complications during treatment. For a reduction in DLCO, the significant factors were administration of anthracyclines, craniospinal irradiation and bone marrow transplantation. Survivors of acute leukemia have impaired pulmonary function and exercise capacity. Long-term cardiopulmonary follow-up may be necessary and new regimens devised which reduce long-term toxicity without compromising survival rates. © 1995 Wi1ey-Liss Inc.     

Exertional Oscillatory Ventilation During Cardiopulmonary Exercise Test in Fontan Patients with Total Cavopulmonary Connection

Exertional oscillatory ventilation (EOV) has been noted during cardiopulmonary exercise testing (CPX) in patients with heart failure. EOV is a predictor of poor prognosis in adult patients with heart failure. The objective of this study was to clarify the incidence and influence of EOV in Fontan patients. Symptom-limited CPX was performed in 36 Fontan patients at 12.3 ± 4.3 (6.5–24.4) years of age or 5.9 ± 2.0 (3.0–11.2) years after total cavopulmonary connection (TCPC). Mean age at the time of TCPC was 6.3 ± 3.3. All 36 TCPC patients were classified as New York Heart Association classification I or II. They also underwent cardiac catheterization subsequently. EOV was defined as cyclic fluctuations in minute ventilation at rest that persist during effort lasting ≥60% of the exercise duration, with an amplitude ≥15% of the average resting value. EOV was noted in 21 of 36 Fontan patients (58%) with good clinical status. Univariable analysis between Fontan patients with and those without EOV showed significant differences in age at TCPC (p < 0.05), age at CPX (p < 0.02), weight at CPX (p < 0.02), follow-up duration between TCPC and CPX (p < 0.04), ventricular morphology (p < 0.05), and metabolic equivalents (p < 0.05) and peak minute oxygen uptake (VO₂) per body weight (p < 0.05). Multivariable analysis showed that EOV was significantly related to peak VO₂ per kilogram. In conclusion, EOV was frequently noted during exercise in Fontan patients with good clinical status. EOV during exercise seems to be related to higher peak VO₂ per kilogram and younger age at TCPC, which is a contrary result to those for adult patients with chronic heart failure. EOV is a remarkable phenomenon during exercise to compensate for impaired cardiopulmonary function in 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.     

The effect of physical training in children with asthma on pulmonary function, aerobic capacity and health-related quality of life: a systematic review of randomized control trials

Objective. Asthma is a leading cause of chronic illness in children, impacting heavily on their daily life and participation in physical activity. The purpose of this systematic review was to investigate the evidence for the use of physical therapy to improve pulmonary function and aerobic capacity in children with asthma. Furthermore, the review aims to update previous literature on the effect of exercise on health related quality of life. Methods. A search was conducted for randomized control trials (RCTs) using the electronic databases Medline, Embase, SPORTDiscus, AMED, CINAHL, and The Cochrane Central Register of Controlled Trials. Studies were included if the participants were asthmatic children aged 6-18 years participating in any mode of physical exercise. Studies were reviewed for study quality, participant details, exercise intervention details, and intervention outcomes. Results. A total of 16 studies and 516 subjects met inclusion criteria for review. Severity of asthma ranged from mild to severe. No improvement in pulmonary function was observed. Physical training led to an increase in aerobic capacity as measured by VO2max (mL/kg/min). Conclusions. Findings suggest that physical training does not improve pulmonary function in children with asthma, but does increase aerobic capacity. The small number of studies investigating quality of life suggests that physical training does improve health related quality of life; however further well designed randomized control trials are needed to verify these findings.     

Eight-year follow-up of pulmonary function and oxygen uptake during exercise in 16-year-old males with cystic fibrosis

Eight of nine Norwegian 16-year-old males with cystic fibrosis, and six age-matched, physically active controls were included in an eight-year follow-up study, involving pulmonary and bicycle exercise testing. The individual's level of regular physical exercise was registered, and we investigated whether or not this could be correlated to changes in clinical status, lung function and maximal oxygen uptake. Four males with cystic fibrosis trained regularly for 4-7 h weekly, while the other four patients did no regular exercise. Three of the latter died during the study, and the fourth male in the non-training group deteriorated significantly during the study period of eight years. The four males in the training group showed improvement in lung function parameters and maximal oxygen uptake, but two of them had more marked obstructive lung disease after the age of 24 years. Even though the sample was small, and several other factors may influence the results, the study indicates that regular physical exercise has beneficial long-term effects on clinical status, lung function and physical fitness in adolescent cystic fibrosis males.     

Ventricular energetics in Fontan circulation: Evaluation with a theoretical model

BACKGROUND: Both pulmonary and systemic circulation must be maintained by a single pump in Fontan circulation. This unique property of Fontan circulation may be related to decreased exercise tolerance or increased instantaneous postoperative mortality rate, often observed in patients with this circulation. To better understand Fontan physiology, the present study theoretically investigated cardiac performance of Fontan circulation by using ventricular-vascular coupling framework analysis. METHODS: End-systolic volume elastance (Ees), as a chamber contractile property, and effective arterial elastance (Ea), a lumped measure of ventricular afterload, were estimated both in normal left ventricular systemic circulation and in Fontan circulation. RESULTS: End-systolic volume elastance was decreased and Ea was increased in Fontan circulation. Both ventricular external stroke work (SW) and mechanical efficiency (EFF) under Fontan circulation were lower compared with those under normal circulation. Furthermore, the Ees-Ea relationship in Fontan circulation predicted limited cardiac reserve in terms of SW and EFF. Such cardiac performance in Fontan circulation stemmed from increased impedance due to the additional connection of the pulmonary vascular bed to the systemic vasculature and from the lack of a compensatory increase in contractility for increased afterload. CONCLUSIONS: Thus, it was inferred that Fontan circulation had intrinsic disadvantages and this may explain, in part, abnormal functional status and decline in survival following this procedure.     

Effect of Tadalafil on Myocardial and Endothelial Function and Exercise Performance After Modified Fontan Operation

Better postoperative management of patients who have undergone single ventricle (SV) Fontan procedure could potentially reduce long-term complications and improve the quality of life for patients. The present study determined the effect of tadalafil on myocardial and endothelial function and exercise performance after modified Fontan operation. Patients who had undergone SV modified Fontan operation were enrolled in this clinical trial. The demographic characteristics of the patients were recorded. Before administration of tadalafil and after the trial, ventricular function (MPI, EF, FS, E/A, VTI), exercise performance, and endothelial function were evaluated for sonographic and biochemical markers (FMD, IMT, ICAM, VCAM, NO) using echocardiography, exercise testing, vascular ultrasonography, and biochemical measurements, respectively. A single dose of tadalafil of 1 mg/kg was administered daily for 6 weeks, and the functional class of the patients before and after tadalafil was determined. A total of 15 patients completed this clinical trial. Tadalafil was shown to have a significant effect on myocardial function, exercise performance, and improvement in NYHA functional class (p < 0.05) of study population. It had no significant effect on the biochemical variables and endothelial function except for IMT (p > 0.05), which decreased significantly after tadalafil administration (p < 0.05). The findings indicate that tadalafil is a safe, well-tolerated agent for the use after modified Fontan operation to improve myocardial function and exercise performance and possibly reduce long-term morbidity and mortality of patients. More conclusive results could be obtained from further study with a larger sample size and long-term follow-up.     

CT findings in unilateral hepatopulmonary syndrome after the Fontan operation

Background  Patients with complex congenital heart defects palliated by connecting the systemic veins directly to the pulmonary circulation are known to develop hepatopulmonary syndrome (HPS). Although rare, HPS can develop following the Fontan operation. Objective  To present and analyse the CT findings of HPS in patients with a Fontan circulation. Materials and methods  From May to December 2005, six patients with HPS following the completion of a Fontan circulation were evaluated. CT findings were reviewed and were compared with angiographic findings. Results  All six patients showed unilateral involvement. All patients except one had inferior vena cava (IVC) interruption with azygos continuation. CT scans showed abnormal vascular dilatation in one lung, and properly demonstrated the anatomy causing the hepatic venous blood to flow preferentially into one lung. These CT findings correlated well with the angiography findings. Conclusion  HPS that develops after the Fontan procedure is typically unilateral and is often associated with IVC interruption and azygos or hemiazygos continuation. CT demonstrates dilatation of pulmonary vessels in the affected lung and may be able to demonstrate the underlying anatomical cause for the predilection of hepatic venous flow to the contralateral lung.     

Physical activity levels in children and adolescents are reduced after the Fontan procedure, independent of exercise capacity, and are associated with lower perceived general health.

OBJECTIVES: To determine physical activity levels in paediatric patients who underwent the Fontan procedure, and their relationship to functional status and exercise capacity. STUDY DESIGN: We studied 147 patients (ages 7-18 years) at a median of 8.1 years after Fontan, as part of the Pediatric Heart Network cross-sectional study of Fontan survivors. Assessment included medical history, self-reported physical activity, parent-completed Child Health Questionnaire (CHQ), cardiopulmonary exercise testing and physical activity level measured by accelerometry (MTI Actigraph). RESULTS: Measured time spent in moderate and vigorous activity was markedly below normal at all ages, particularly in females, and was not significantly related to self-reported activity levels, or to maximum Vo2, Vo2 at anaerobic threshold or maximum work rate on exercise testing. Lower measured activity levels were significantly related to lower perceived general health but not to self-esteem, physical functioning, social impact of physical limitations or overall physical or psychosocial health summary scores. Reduced exercise capacity was more strongly related than measured activity levels to lower scores in general health, self-esteem and physical functioning. CONCLUSIONS: Physical activity levels are reduced after Fontan, independent of exercise capacity, and are associated with lower perceived general health but not other aspects of functional status.     

Hypoplastic left heart syndrome.

HLHS is a complex developmental malformation of the left ventricle, aorta, and associated valves. Survival beyond neonatal life is the exception in untreated infants. The prognosis, however, is no longer hopeless. Newer surgical strategies of staged palliative reconstruction and heart replacement by transplantation appear promising. These options on occasion will become complementary in the management of individual patients. Those children surviving Fontan operations are frequently able to lead NYHA Class I or II lives without drugs, while transplant recipients will require one or more immunoregulative medications indefinitely. Exercise tolerance and work capacity following the Fontan procedure are reported to be 40 to 60 per cent of expected normals. Full functional capacity of successfully palliated children may never be normal. In contrast, exercise capability after heart transplantation is generally better than that following a Fontan operation, with cardiac ejection fractions approaching normal for age. Durability of these new management technologies will make inappropriate the traditional "do nothing" approach to HLHS in all but a few cases.     

Effects of Transcatheter Closure of Fontan Fenestration on Exercise Tolerance

Baffle fenestration is associated with a significantly better outcome in standard and high-risk patients undergoing completion of Fontan. We report the effects of subsequent transcatheter closure of fenestration on exercise capacity and oxygen saturation. Sixteen patients with a mean age of 10.3 years underwent Amplatzer septal occluder (ASO) device transcatheter closure of Fontan fenestration. All had a fenestrated Fontan operation 6 month to 8 years prior to the procedure. A stress test was performed before and after device closure of fenestration in 14 patients (2 patients did not tolerate stress test before the procedure). The fenestrations in all patients were successfully occluded with the use of the Amplatzer device occluder. No complications occurred during or after the procedure. O₂ saturation increased from a mean 85.1 ± 7.89% to 94.5 ± 3.63% (p < 0.01) at rest and from 66.2 ± 12.86% to 87.2 ± 8.64% (p < 0.01) following exercise. Exercise duration has also increased from 8.22 ± 2.74 min to 10.29 ± 1.91 min (p < 0.05). Transcatheter closure of Fontan fenestration increases the duration of exercise capacity and increases O₂ saturation at rest and after exercise.     

Pulmonary complications of congenital heart disease

Cardiac and pulmonary pathophysiologies are closely interdependent, which makes the management of patients with congenital heart disease (CHD) all the more complex. Pulmonary complications of CHD can be structural due to compression causing airway malacia or atelectasis of the lung. Surgical repair of CHD can also result in structural trauma to the respiratory system, e.g., chylothorax, subglottic stenosis, or diaphragmatic paralysis. Disruption of the Starling forces in the pulmonary vascular system in certain types of CHD lead to alveolar-capillary membrane damage and pulmonary oedema. This in turn results in poorly compliant lungs with a restrictive lung function pattern that can deteriorate to cause hypoxemia. The circulation post single ventricle palliative surgery (the so called "Fontan circulation") poses a unique spectrum of pulmonary pathophysiology with restrictive lung function and a low pulmonary blood flow state that predisposes to thromboembolic complications and plastic bronchitis. As the population of patients surviving post CHD repair increases, the incidence of pulmonary complications has also increased and presents a unique cohort in both the paediatric and adult clinics.     

The Fontan Circulation: What Have We Learned? What to Expect?

Our knowledge of the Fontan operation tends to indicate that it remains a palliative procedure for patients with a functionally single ventricle. There is a continuing attrition and the life expectancy of these patients is likely to be different from the life expectancy of a population of individuals having a biventricular circulation. This article is an essay on the rational approach for the future management of these patients. It is suggested that a better understanding of the continuing Fontan attrition and a more subtle way to predict outcomes of patients who do receive the Fontan could help in establishing better selection criteria and designing ways to prevent, delay, or treat the side-effects of this late attrition.     

IMPROVEMENT AFTER TRAINING OF CHILDREN WITH EXERCISE-INDUCED ASTHMA

ABSTRACT. Fifty children with exercise-induced asthma (EIA) volunteered to take part in a study of the influence of training on EIA. 1) Ten children did not change physical activity. 2) Twelve children trained after premedication with salbutamol inhalations. 3) Thirteen children trained after premedication with disodium chromoglicate (DSCG) and used that drug for treatment. 4) Fifteen children trained in their own regimen, commonly after premedication with salbutamol. Their training programme (groups 2-3) consisted of high load exercise periods of two minutes interrupted by intervals of rest for two minutes during 30 minutes followed by interval swimming for another 30 minutes, twice a week for 3-4 months. Before the training period the degree of EIA was tested with a battery of lung function tests before and after running for 6 minutes on a treadmill at heart rate 170. EIA after training was measured applying the same procedure. Cardiocirculatory performance was evaluated before and after training with work on a cycle ergometer and expressed as W/kg body weight at heart rate 170. The children in groups 2, 3 and 4 improved their physical working capacity by 11% ( p <0.01), 21% and 11%, respectively, but no improvement was found in group 1. Significant improvements in EIA after the training periods were found in all training groups, but basal asthma improved most in group 3, probably due to the basal treatment with DSCG.