Restrictive versus nonrestrictive physiology following repair of tetralogy of Fallot: is there a difference?

BACKGROUND: Long-term outcome in repaired tetralogy of Fallot (TOF) is related to chronic pulmonary insufficiency (PI), right ventricular (RV) dilation, and deterioration of RV function. The aim of this study was to characterize clinical differences between restrictive and nonrestrictive RV physiology in young patients with repaired TOF. METHODS: Patients were prospectively enrolled from February 2008 to August 2009. Each had a clinic visit, brain natriuretic peptide assessment, exercise test, cardiac magnetic resonance study, and echocardiographic examination with assessment of regional myocardial mechanics. Consistent antegrade diastolic pulmonary arterial flow with atrial contraction identified restrictive RV physiology. RESULTS: Twenty-nine patients (median age, 12 years; range, 8-33 years; nine male patients) were studied. Twelve had restrictive RV physiology. The median time since initial TOF repair was 12 years (range, 5-27 years). Restrictive physiology appeared more prevalent after transannular patch repair and was not influenced by other demographic features. The restrictive group had more PI (46% vs 28%, P = .002), larger RV end-diastolic volumes (128 vs 98 mL/m(2), P = .046), but similar ejection fractions, brain natriuretic peptide levels, New York Heart Association classes, and exercise capacity. RV basal and mid free wall peak diastolic strain rate differed between groups, negatively correlating with exercise time and positively correlating with PI in patients with restrictive physiology. CONCLUSIONS: Restrictive RV physiology correlates with a larger right ventricle and increased PI after TOF repair but does not negatively affect other markers of myocardial health. Diastolic regional RV myocardial mechanics, particularly diastolic velocity and peak diastolic strain rate, differ for postoperative TOF patients with restrictive and nonrestrictive RV physiology; longitudinal study is necessary to understand the relationship of regional myocardial mechanics and patients' clinical status.

Restrictive lung disease is an independent predictor of exercise intolerance in the adult with congenital heart disease.

BACKGROUND/OBJECTIVES: Following repair of congenital heart disease (CHD), adult patients are at risk for reduced exercise capacity. Restrictive lung disease (RLD) may contribute to reduced exercise capacity in this population. The aim of this study was to determine the prevalence of RLD and its impact on exercise tolerance in the adult with CHD. METHODS: One hundred consecutive adult patients with CHD, who underwent routine cardiopulmonary exercise testing with spirometry, were evaluated. Clinical data were obtained by retrospective chart review. RESULTS: Patients from 10 major diagnostic groups were identified. The median age for the cohort was 31 years (range 18-63) and included 43 males and 57 females. Most patients, 79%, had at least one previous surgical procedure. Based on spirometry and flow/volume loops, 50 patients were classified as normal pulmonary function, 44 patients had patterns suggestive of RLD, 4 suggestive of mixed (obstructive and restrictive), and 2 indeterminate. Risk factors associated with RLD include history of multiple thoracotomies (odds ratio = 9.01, P =.05) and history of atrial arrhythmias (odd ratio = 4.25, P =.05). Overall, 56% of the patients had abnormal exercise capacity. Spirometry suggestive of RLD was a significant risk factor for decreased exercise capacity (odds ratio = 3.65, P =.03). Patients with spirometry suggesting RLD also had lower exercise duration (P =.004) and a higher New York Heart Association Functional Class (P =.02). History of previous surgery and decreased heart rate reserve were also significant risk factors for decreased exercise capacity. CONCLUSION: Abnormal spirometry suggestive of RLD is common in the adult with CHD and is a significant risk factor for decreased exercise tolerance in this population. Further studies are needed to evaluate the relationship between RLD and exercise intolerance and its relationship to mortality in the adult with CHD.

Near-infrared spectroscopic monitoring during cardiopulmonary exercise testing detects anaerobic threshold.

Cardiopulmonary exercise testing (CPET) provides assessment of the integrative responses involving the pulmonary, cardiovascular, and skeletal muscle systems. Application of exercise testing remains limited to children who are able to understand and cooperate with the exercise protocol. Near-infrared spectroscopy (NIRS) provides a noninvasive, continuous method to monitor regional tissue oxygenation (rSO2). Our specific aim was to predict anaerobic threshold (AT) during CPET noninvasively using two-site NIRS monitoring. Achievement of a practical noninvasive technology for estimating AT will increase the compatibility of CPET. Patients without structural or acquired heart disease were eligible for inclusion if they were ordered to undergo CPET by a cardiologist. Data from 51 subjects was analyzed. The ventilatory anaerobic threshold (VAT) was computed on [Formula: see text] and respiratory quotient post hoc using the standard V-slope method. The inflection points of the regional rSO2 time-series were identified as the noninvasive regional NIRS AT for each of the two monitored regions (cerebral and kidney). AT calculation made using an average of kidney and brain NIRS matched the calculation made by VAT for the same patient. Two-site NIRS monitoring of visceral organs is a predictor of AT.

Near infrared spectroscopy describes physiologic payback associated with excess postexercise oxygen consumption in healthy controls and children with complex congenital heart disease.

Exercise creates a physiologic burden with recovery from such effort crucial to adaptation. Excess postexercise oxygen consumption (EPOC) refers to the body's increased metabolic need after work. This investigation was designed to determine the role of near infrared spectroscopy (NIRS) in the description of exercise recovery in healthy controls (NL) and children with congenital heart disease (CHD). Subjects were recruited with exercise testing performed to exhaustion. Exercise time (EXT), heart rate (HR), and oxygen consumption (VO(2)) were measured. Four-site NIRS (brain, kidney, deltoid, and vastus lateralis) were measured during exercise and into recovery to establish trends. Fifty individuals were recruited for each group (NL = 26 boys and 24 girls; CHD = 33 boys and 17 girls). Significant differences existed between EXT, VO(2), and peak HR (P < 0.01). NIRS values were examined at four distinct intervals: rest, peak work, and 2 and 5 min after exercise. Significant cerebral hyperemia was seen in children with CHD post exercise when compared to normal individuals in whom redistribution patterns were directed to somatic muscles. These identified trends support an immediate compensation of organ systems to re-establish homeostasis in peripheral beds through enhanced perfusion. Noninvasive NIRS monitoring helps delineate patterns of redistribution associated with EPOC in healthy adolescents and children with CHD.

Objectively assessed physical activity and sedentary behaviour does not differ between children and adolescents with and without a congenital heart defect: a pilot examination.

OBJECTIVES: To objectively evaluate and describe physical activity levels in children with a stable congenital heart defect and compare those levels with children who do not have a congenital heart defect. METHODS: We matched 21 pairs of children for gender and grade in school and gave them an accelerometer-based motion sensor to wear for 7 consecutive days. RESULTS: Physical activity levels did not differ between children with and without a congenital heart defect. During the 7 days of monitoring, children in this study spent most of their time in sedentary behaviours, that is, 6.7 hours of the 13 monitored hours, 54 minutes in moderate-intensity physical activity, and 12 minutes in vigorous-intensity physical activity. Less than one-fifth of all participants, with or without a congenital heart defect, accumulated sufficient physical activity to meet current physical activity recommendations for children and adolescents. CONCLUSION: Children with a stable congenital heart defect have activity behaviours that are similar to children without a congenital heart defect. Habitual physical activity in children with a congenital heart defect should be encouraged early on in life to develop strong physical activity habits that will hopefully follow them across their lifespan.

Near infrared spectroscopy: guided tilt table testing for syncope.

Syncope is transient loss of consciousness. Neurocardiogenic syncope (NCS) is the most common cause of syncope. Head-up tilt-table test (HUTT) has been used to demonstrate physiologic events during graded orthostatic challenge in individuals with significant handicap from NCS. Near-infrared spectroscopy (NIRS) provides a noninvasive, continuous method to monitor trends of regional tissue oxygenation (rSO2). We hypothesize that multisite NIRS monitoring will show differential desaturation patterns in the brain and renal vascular beds during postural stresses. All patients age 7-21 years old scheduled to undergo HUTT were recruited. Two probes for NIRS monitoring were placed on the forehead and above the left paravertebral level at the T10 to L1 space. These leads were attached to the Somanetics monitor (Somanetics, Troy MI). Tissue saturations (rSO2) obtained at two sites were recorded at rest, during the test, and throughout a 5-min recovery period. All data routinely obtained in HUTT were included in the research study database. Thirteen patients were recruited. The average age was 12.9 years. Five patients had a positive tilt-table test. The patients with syncope had rSO2 trends distinctly different from the normal subjects. In these patients, cerebral rSO2 showed a sudden decreasing trend from hypoperfusion, soon followed by various clinical symptoms. The cerebral rSO2 trend, which showed a dramatic increase, was paralleled by renal rSO2. These rSO2 trends were progressive until the patient was brought back to the supine position, which resulted in the rSO2 in both beds returning to baseline. Multisite NIRS-guided HUTT shows differential trends in the different vascular beds during postural gravitational stresses, and these patterns underlie the systemic oxygen consumption to flow-coupling dynamics observed during syncope.

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.

Measurement of regional tissue bed venous weighted oximetric trends during exercise by near infrared spectroscopy.

BACKGROUND: Cardiopulmonary exercise testing (CPET) is limited to children able to tolerate the equipment. Modification of instrumentation to reduce invasiveness will open CPET to a wider population. Near Infrared Spectroscopy (NIRS) devices measure regional oxyhemoglobin saturation (rSO2). We aim to predict anaerobic threshold (AT) during CPET using multiorgan NIRS monitoring. METHODS AND RESULTS: Nineteen subjects were recruited. NIRS probes were placed on the forehead, para vertebral space, vastus lateralis, and deltoid muscle (rSO2 C, rSO2 R, rSO2 L and rSO2 A). rSO2 was recorded at six second intervals at rest, exercise, and through a five minute recovery period. The AT was computed using the v-slope method. AT was also predicted using NIRS data by identifying the inflection point of the rSO2 trends for all the four sites. AT can be estimated by the point of slope change of rSO2 R, rSO2 C and the four-site composite measure. CONCLUSIONS: Multisite NIRS monitoring of visceral organs is a potential predictor of AT. This allows for monitoring in all forms of exercise over a wide age range.

Chest pain: characteristics of children/adolescents.

Chest pain (CP) in children/adolescents is a common referral for the pediatric cardiologist. A group of 263 patients (141 males/122 females, mean age = 13.4 years, range = 5-22 years) with the primary complaint of CP underwent evaluation in the cardiac stress lab at Children's Hospital of Wisconsin. Echocardiograms at rest were obtained in 70% of patients with no significant cardiac abnormalities identified. Endurance time (EXT) and oxygen consumption (VO(2)/kg) were below predicted in 26% and 46%, respectively. Reactive airway disease (RAD) as a preexisting condition was reported in 19% of patients, but abnormal resting pulmonary function (PFTs) were found in 26% (n = 68), with 48/68 never having the diagnosis of RAD. At risk of overweight (BMI >85th percentile), was seen in 28% of the cohort, with 16% identified as being overweight (BMI >95th percentile). A significant difference in RAD (p < 0.01) was seen in African Americans (AA) and decreased EXT (p = 0.01) was seen in Hispanics (H). VO(2)/kg was significantly reduced in both AA and H (p < 0.01). These results identify both racial and age-related differences in the etiology of CP in children. Most importantly, true cardiac pathology is extremely rare. AOW, deconditioning, and respiratory compromise play important roles in CP. The need for comprehensive cardiopulmonary monitoring is emphasized by these findings.

Exercise recommendations and risk factors for sudden cardiac death.

This article reviews the risk factors that are associated with exercise that can lead to sudden cardiac death and what can be done to identify those who are at risk. Additionally, exercise recommendations to reduce the chance of sudden cardiac death and comments about restrictions and quality of life issues are addressed.