Cardiorespiratory exercise performance after Senning operation for transposition of the great arteries.

OBJECTIVE: To assess the cardiorespiratory response to graded exercise in patients after the Senning operation for transposition of the great arteries. DESIGN: Cross sectional study. Exercise performance was assessed by determination of the ventilatory anaerobic threshold. This was defined as the exercise intensity at which the ventilatory equivalent for oxygen (VE/VO2) started to increase systematically without a concomitant increase in the ventilatory equivalent for carbon dioxide (VE/VCO2). SETTING: Outpatient department. PATIENTS: Sequential sample of 20 patients studied 5-10 years (mean 7.3 years) after the Senning operation. Age at exercise testing varied from 5 to 11 (mean 7.8) years. RESULTS: The ventilatory threshold in the patients was significantly lower than normal (p < 0.005) and averaged 79.3% (SD 13%) and 80% (12%) of the predicted normal value for age and weight, respectively. Also, the ventilatory threshold was surpassed sooner (mean 3.2 (range 2-5) minutes) in the patients than in normal controls (3.9 (2.6-4.6) minutes). The lower ventilatory threshold was associated with a subnormal oxygen uptake (ml/min/kg) during submaximal exercise, a higher than normal ventilatory equivalent for oxygen ratio, and a lower end tidal carbon dioxide tension in the patients compared with normal controls. In half of the patients heart rate was lower during graded exercise. This relative bradycardia was not associated with a normal ventilatory threshold, as often seen in fit young people. No major disturbances in rhythm were observed during exercise. CONCLUSION: Exercise performance, assessed by respiratory gas exchange, was slightly but significantly lower than normal in patients after the Senning operation. A subnormal ventilatory threshold, associated with a higher than normal ventilatory response during submaximal exercise, supports the hypothesis that oxygen delivery to tissues is slightly impaired in these patients.

Evaluation of breath-by-breath measurement of respiratory gas exchange in pediatric exercise testing.

In adults, breath-by-breath analysis has been used for measuring respiratory gas exchange during exercise. The present study evaluates the validity and reproducibility of this method in children. In 21 patients with various types of congenital heart disease, steady state exercise testing was performed on a motor-driven treadmill. Based on simultaneous measurements of VO2, VCO2, VE and R, comparisons were made between the breath-by-breath and Douglas bag methods. No significant differences were found between both methods for any of the variables. In seven other patients the reproducibility of cardiorespiratory variables during exercise was assessed. No significant difference was found for the cardiorespiratory variables during any of the tests and the coefficients of variation were comparable to data obtained in adults. It is concluded that the breath-by-breath method for measuring respiratory values can be applied in children with an acceptable degree of validity and reproducibility.

Cardiorespiratory exercise capacity after surgical closure of atrial septal defect is influenced by the age at surgery.

To study the influence of age at the time of the operation on long-term functional performance in children undergoing surgery for atrial septal defect (ASD) of the secundum type, exercise tolerance was assessed in 24 patients and values were compared with those of normal subjects. Patients were divided into two groups: 11 patients had surgery before the age of 5 years (group 1) and 13 patients had surgery at a later age (group 2). There were no significant differences between groups 1 and 2 with regard to the pulmonary-to-systemic flow ratio, pulmonary artery pressure, and the interval between surgery and exercise testing. Performance capacity was assessed by determination of the ventilatory threshold during submaximal exercise. The mean value for the ventilatory threshold in group 1 was normal (99.4 +/- 15.1% of the age-predicted normal value). In the children who were more than 5 years of age at the time of the operation, the ventilatory threshold was below normal (84.5 +/- 10.9% of the age-predicted normal value). Furthermore, in group 2 more patients (77%) had values that were below normal (below the 95% confidence limit of the age-predicted normal value) compared with group 1 (27%). It is concluded that functional performance capacity is better when surgical closure of ASD is performed in early childhood and before the age of 5 years rather than at a later age.

Cardiorespiratory response to exercise in congenital complete atrioventricular block.

In 8 patients aged 8 to 17 years with congenital complete atrioventricular (AV) block, exercise testing was performed on a treadmill. Cardiorespiratory endurance performance was assessed by determination of the ventilatory threshold. The mean value for ventilatory threshold was significantly lower (p less than 0.005) than the normal mean value and averaged 76 +/- 16%, 75 +/- 17% and 75 +/- 16% of the predicted normal value in children of the same sex and comparable age, weight and height, respectively. The ventricular rate at rest varied from 36 to 56 beats/min and increased to a mean value of 106 +/- 25 on exercise. When expressed as a percentage of the normal value, the heart rate was subnormal (below the 95% confidence limit) in all patients, throughout different exercise levels. For the same exercise intensity the oxygen uptake, expressed as ml/min/kg, was significantly lower (p less than 0.02) in patients than in normal individuals. This suggests an inadequate hemodynamic adjustment to the relative exercise bradycardia and a higher than normal anaerobic/aerobic energy supply. Exercise testing was found to be useful in the assessment of congenital AV block, because the resting heart rate did not permit prediction of the relative exercise bradycardia or the degree of exercise intolerance.

Transient neonatal tricuspid regurgitation: a Doppler echocardiographic study of three cases.

Three patients with normal hearts and no pulmonary abnormality had neonatal tricuspid regurgitation causing cardiorespiratory distress and cyanosis. The signs of tricuspid regurgitation resolved over a few weeks. In the acute phase echocardiography showed gross dilatation of the right atrium and ventricle. The interatrial septum bulged into the left atrium during the whole cardiac cycle. Doppler echocardiography showed clinically significant tricuspid regurgitation, a right to left shunt through the foramen ovale, reduced flow through the pulmonary valve, and in two patients ductal flow into the pulmonary artery. In one patient tricuspid regurgitation was so great that it impeded the opening of the pulmonary valve and produced functional "atresia" of the pulmonary valve. The presence of regurgitant blood flow through the pulmonary valve showed that the "atresia" was functional rather than organic. Doppler echocardiographic study is useful in distinguishing functional neonatal tricuspid regurgitation from structural abnormality of the tricuspid valve.

Cardiorespiratory exercise testing after venous switch operation in children with complete transposition of the great arteries.

In 14 children who underwent a venous switch operation for complete transposition of the great arteries, exercise testing was performed 3 to 15 years (mean 8) after the operation. Exercise performance capacity was assessed by the determination of the ventilatory threshold during exercise and by the oxygen uptake (VO2) reached at a heart rate of 170 beats/min (VO2,170). The ventilatory threshold was defined as the highest oxygen uptake (VO2) at which the pulmonary ventilation (VE) stops to increase linearly when related to VO2. During exercise above this threshold a disproportionate increase in VE relative to VO2 is observed. The mean ventilatory threshold was significantly lower (p less than 0.01) than the normal mean value and averaged 72 +/- 15%, 67 +/- 15% and 70 +/- 13% of the predicted normal value for children of comparable age, weight and height, respectively. The mean value for VO2,170 also was significantly lower (p less than 0.05) than the normal mean value for children of comparable age, weight and height, and averaged 81 +/- 20%, 81 +/- 18% and 80 +/- 18%, respectively. Compared with normal control subjects of the same sex and age, the ventilatory threshold was surpassed sooner (p less than 0.001) and reached after 2 +/- 1 min instead of the 4 +/- 1 min required by the controls. In nearly half of the patients, a lower than normal (i.e. below the 95% confidence limit) heart rate response to exercise was observed. Theoretically, this could be interpreted as indicating a normal or high physical performance capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac chamber growth pattern determined by two-dimensional echocardiography.

Two-dimensional echocardiographic measurements of the right and left ventricles from the parasternal long-axis and apical four-chamber views and an estimated right ventricular-left ventricular dimensional ratio were obtained in 173 normal subjects, ranging from 1 day to 15 years of age. The end-diastolic dimensions of both the right and left ventricles increases in proportion to the logarithmic function of body surface area. The right ventricular-left ventricular dimensional ratio decreases immediately after birth and continues to decrease during the first months of life. Newborns have altered ventricular shapes as seen in the pathological conditions of right ventricular volume or pressure overload. After the first months of life, the ventricular shapes remain constant throughout childhood. The 95% prediction intervals for the data were computed, and we suggest that the confidence limits of the normal data may be useful for quantitative echocardiographic evaluation in childhood.

Cross sectional echocardiographic assessment of great artery diameters in infants and children.

The pulmonary trunk and aortic root were measured on cross sectional echocardiograms in 173 normal subjects aged from one day to 15 years. Fifteen neonates were reexamined 3-6 days later. The great vessels were visualised in the parasternal long axis and short axis views. All measurements were made in end diastole and end systole by the leading edge method. The internal diameter (inner surface to inner surface) of the pulmonary trunk was also measured. The diameters of the great vessels correlated best with the square root of body surface area. Individual variability in cardiac growth gave a wide scatter of normal values. This was controlled for by calculating the ratio of the pulmonary trunk to aortic root for each subject. This ratio showed little individual variability and, except for the neonatal period, was remarkably constant throughout infancy and childhood (1.06 (0.06)). In the first 24 hours of life the ratio of the pulmonary trunk to the aortic root was significantly larger (1.29 (0.12)) but within one week it decreased to the "normal" ratio found in the older age groups. These normal data should be useful in assessing patients with congenital heart disease, particularly those in whom pulmonary blood flow is abnormal.

Interrupted right aortic arch in DiGeorge syndrome.

The clinical and necropsy findings in four cases of interrupted right aortic arch and right descending aorta associated with DiGeorge syndrome (congenital absence or hypoplasia of the thymus and parathyroids) are described. All patients had a mirror image of type B interruption, namely a right aortic arch with reversed branching pattern and an interruption between the right common carotid and right subclavian artery. In two patients there was a doubly committed subarterial ventricular septal defect and in the two other patients there was a perimembranous septal defect. Three patients had a bicuspid aortic valve. In a consecutive series of 185 necropsies in infants and children with congenital heart disease there were no cases of interrupted right aortic arch that were not associated with DiGeorge syndrome. These observations and previous reports indicate that the concurrence of these two rare conditions is more than fortuitous. In patients with an interrupted aortic arch the clinician should be aware of the common association with DiGeorge syndrome. If the interruption is associated with a right-sided descending aorta it is highly probable that the patient has DiGeorge syndrome.

Exercise testing after correction of tetralogy of Fallot: the fallacy of a reduced heart rate response.

Thirty-nine patients, 5 to 19 years of age, were studied 1 to 10.5 years (mean 4.5) after surgical correction of tetralogy of Fallot (TF). In 32 of them the results of an exercise performance test based on heart rate response to submaximal exercise (VO2, 170 [bpm]) was compared with another index of physical performance capacity, which is independent from heart rate: the ventilatory threshold. In patients operated for TF, the mean heart rate during exercise was significantly lower than that corresponding to the same level of exercise in normal children (p less than 0.001) and their mean VO2, 170 was normal. Theoretically, these findings could be interpreted as indicating a normal or high physical performance capacity. By contrast, the ventilatory threshold was significantly lower than that in normal children: it averaged 89.3 +/- 15.7%, 79.7 +/- 14.4%, and 88.5 +/- 15.8% of the mean value in normal children matched for age, weight, and height, respectively. More patients had a subnormal value for ventilatory threshold than for VO2, 170: 58% had a ventilatory threshold below the 95% confidence limits for age-matched normal individuals and 75% had a subnormal value when compared to weight-matched normal children. For VO2, 170, these values were 39% and 34%, respectively (p less than 0.05). We recommend the evaluation of the exercise performance capacity in patients operated for TF not only by measuring heart rate response and VO2, 170 which may be misleading because of relative bradycardia, but also by analyzing gas exchange and determining the ventilatory threshold.

Ventilatory anaerobic threshold for evaluating exercise performance in children with congenital left-to-right intracardiac shunt.

The ventilatory response to graded treadmill exercise was studied in 50 children with congenital heart disease (CHD), a left-to-right intracardiac shunt, and compared to that of age and sex-matched healthy children. In all these children, a breakpoint in the minute ventilation (VE) in relation to increasing oxygen uptake (VO2) was detected. Because of the reported coincidence of the nonlinear increase in VE and lactate with increasing VO2, this threshold has been named "ventilatory anaerobic threshold" (VAT), expressed in ml O2 X min-1 X kg-1. VAT correlated well with VO2 (ml X min-1 X kg-1), reached at a heart rate of 170/min (VO2,170). Compared to normal children, however, a significantly (p less than 0.05) larger percentage (56%) of the patients showed a subnormal value (below the 95% confidence limit) for VAT than for VO2,170 (28%). Furthermore, when expressed as a percentage of the mean normal value, the mean VAT (89 +/- 14.4% SD) was significantly (p less than 0.05) lower than the mean VO2,170 (103 +/- 17.2%). VAT (ml O2 X min-1) correlated significantly with body weight and height, even after adjusting for age, and with the percentiles of body weight and height. VAT constitutes a useful noninvasive criterion for evaluating exercise performance in children with CHD, at least those forms with a left-to-right intracardiac shunt, and it is significantly more sensitive than the VO2,170 in detecting decreased cardiorespiratory endurance capacity.

Usefulness of echocardiographic assessment of right ventricular and pulmonary trunk size for estimating magnitude of left-to-right shunt in children with atrial septal defect.

M-mode and 2-dimensional echocardiographic studies were performed in 42 patients, aged 1 to 16 years (mean 6), with a secundum or sinus venosus type atrial septal defect (ASD) and normal pulmonary artery pressure. Twenty normal children served as a control group. In patients with ASD the echocardiographic variables were correlated with the magnitude of the left-to-right shunt (Qp/Qs) calculated by the Fick principle. Although M-mode echocardiograms showed increased right ventricular (RV) dimension in 69% of the patients, the correlation between RV dimension index (RV dimension/body surface area) and Qp/Qs was weak (r = 0.49). When RV dimension was related to left ventricular (LV) dimension and expressed by the RV/LV ratio, 90% of the patients were found to have an abnormally large right ventricle. The correlation between the RV/LV ratio and Qp/Qs was fairly good (r = 0.64). In 33 patients (78%), the pulmonary trunk (PT) was adequately visualized and measured on 2-dimensional echocardiograms. The dimension of the PT was related to the aortic root dimension and expressed by the PT dimension/aortic dimension ratio. This ratio was 0.99 +/- 0.06 in normal children and 1.35 +/- 0.23 in patients with ASD (p less than 0.001). The PT/aortic ratio exceeded the upper limit of normal (the normal mean value + 2 standard deviations) in each of the 27 patients with a Qp/Qs of 1.5 or greater. In 5 of the 6 patients with a Qp/Qs of less than 1.5 the PT/aortic ratio was close to 1 and within the normal range. An excellent correlation (r = 0.89) was found between the PT/aortic ratio and Qp/Qs.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term echocardiographic assessment of dilated cardiomyopathy in children.

Left ventricular (LV) dimensions and function were assessed by echocardiography in 22 children with dilated cardiomyopathy. They had survived an initial episode of congestive heart failure in infancy for greater than or equal to 2 years. At the time of echocardiography, when they were 3 to 16 years old, 8 patients (Group 1) still had signs of dilated cardiomyopathy and 14 (Group 2) had lost all roentgenographic and electrocardiographic evidence of heart disease. All 8 patients in Group 1 (average follow-up 4.5 years) had significantly increased LV dimensions. The end-diastolic dimension averaged 144 +/- 18% of the normal value. Fractional LV shortening with systole was significantly reduced and averaged 23 +/- 3%. The E point-septal separation ranged from 7 to 17 mm (mean 12 +/- 4) and was far above the normal limit in all. Of the 14 patients in Group 2, seven (average follow-up 7 years) had normal ventricular dimensions and 7 (average follow-up 10 years) had LV dimensions larger than the upper range of the 95% prediction limit. In 6 of the latter patients the fractional LV shortening with systole was less than or equal to 31% and the E point-septal separation in excess of the upper limit of normal. These findings indicate that about half of the patients who had apparently recovered still had residual lesions as judged from the echocardiogram. In 6 patients in group 1, two-dimensional echo-cardiography allowed the visualization of a thickened endocardium. One of these 6 patients died. The echocardiographic image correlated well with the process of LV endocardial fibroelastosis found at necropsy.

Congenital atresia of left coronary ostium.

A two-year-old girl, who presented with congestive heart failure and an extensive anterolateral infarction, was thought to have anomalous origin of the left coronary artery from the pulmonary artery. She improved rapidly and remained symptom free until 13 years of age, when she died suddenly. At necropsy the right coronary artery was found to be normal but in the left aortic sinus a dimple was the only remnant of the left coronary ostium. The proximal segment of the left long term follow-up of a patient with this rare anomaly.

Sick sinus syndrome in childhood.

The clinical and electrocardiographic findings in five children with the sick sinus syndrome and an otherwise normal heart are described. There were three boys and two girls. Their age at onset of either bradycardia or symptoms ranged from 1 day to 7 years. In one patient, the youngest ever reported with this syndrome, bradycardia was noted before birth. Four children presented with neurological symptoms--attacks of dizziness, fainting spells, or syncope. One boy, treated for epilepsy before the underlying arrhythmia ws diagnosed, died suddenly while playing. One child had near-fatal syncope caused by ventricular tachycardia. Continuous 24-hour electrocardiographic monitoring is the best method of assessing the severity of the condition. Sinus bradycardia, sinuatrial block, and periods of sinus arrest up to 4.8 seconds were recorded. Two patients had associated atrioventricular block and were therefore presumed to have binodal disease. Atrial fibrillation or flutter occurred in three patients. Isolated sick sinus syndrome may be a life-threatening condition in childhood for which, in selected cases, the insertion of a permanent pacemaker is indicated.

Cardiovascular malformations in DiGeorge syndrome (congenital absence of hypoplasia of the thymus).

Partial or complete absence of the thymus (DiGeorge syndrome, III-IV pharyngeal pouch syndrome) is often associated with agenesis or hypoplasia of the parathyroid glands and, almost invariably, with cardiovascular malformations. The clinical and pathologcial findings in 10 cases proven at necropsy are presented. All patients presented with cardiac symptoms and signs in the first weeks of life and, with one exception, all died of a cardiac cause. Major cardiovascular malformations were found in all 10 cases. Four had, in association with a ventricular septal defect of the infundibular type, an interrupted aortic arch, which was left-sided in two and right-sided in two other cases. Four patients had truncus arteriosus type I, in two of them associated with a right-sided aortic arch. Two patients with tetralogy of Fallot had a right-sided aortic arch. Only two of the 10 had a normally developed left aortic arch. Aberrant subclavian arteries were found in five cases. From our observations and a survey of the previously published patients it appears that 90 per cent of the necropsy-proven cases of DiGeorge syndrome have cardiovascular malformations and that 95 per cent of these malformations can be classified as aortic arch anomalies, truncus ateriosus, or tetralogy of Fallot.

Aneurysm of the left atrial appendage.

A 2-year old asymptomatic girl is presented in whom the chest x-ray film led to the discovery of a grossly distorted cardiac shadow. Angiocardiography showed a giant aneurysm originating from the left atrium. At operation an intrapericardial aneurysm of the left atrial appendage, measuring 12 X 4 X 4 cm, was found. It communicated with the left atrium through an orifice measuring 3 cm. The aneurysm was excised.

Cardiovascular malformations in Turner's and Noonan's syndrome.

The cardiovascular findings in 9 patients with Turner's syndrome and 9 patients with Noonan's syndrome are described. Of the 9 patients with Turner's syndrome, 4 had coarctation of the aorta, 4 aorta stenosis, and the remaining patient both these lesions. All patients with Noonan's syndrome had pulmonary valve stenosis. In addition, 2 children had an atrial septal defect and 1 an atrial septal defect associated with mild supravalvar pulmonary stenosis and anomalous drainage of the right upper pulmonary veins. In the majority of patients the electrocardiogram was different from the pattern usually seen in pulmonary valve stenosis: the QRS axis in the frontal plane was superiorly oriented in 7 out of 9 cases and in 2 patients evidence of right ventricular hypertrophy was lacking in the right praecordial leads; in 5 patients an rS complex was seen in the left praecordial leads. Gross thickening of pulmonary valve cusps was found at operation in 4 of the 8 patients who were operated on. Although phenotypically related, Turner's and Noonan's syndromes are associated with different and distinct cardiovascular anomalies.