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Ann Thorac Surg 2003;75:935-943
© 2003 The Society of Thoracic Surgeons
kovaa
a Department of Pediatric Cardiology, University Hospital, Aachen University of Technology, Aachen, Germany
b Institute For Medical Research and Information Processing, Aachen, Germany
c Department of Thoracic and Cardiovascular Surgery, University Hospital, Aachen University of Technology, Aachen, Germany
Accepted for publication September 5, 2002.
* Address reprint requests to Dr Hövels-Gürich, Department of Pediatric Cardiology, University Hospital, Aachen University of Technology, Pauwelsstrasse 30, D-52057 Aachen, Germany.
e-mail: hhoevels-guerich{at}ukaachen.de
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Abstract |
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METHODS: Sixty unselected children with intact ventricular septum (78.3%) or ventricular septal defect (21.7%) without or with aortic isthmic stenosis (5.1%) were examined 10.5 ± 1.6 (mean ± SD) years after neonatal switch and 5.3 ± 1.6 years after mid-term evaluation. Complete clinical examination, standard and 24-hour Holter electrocardiogram, M-mode, 2D-, Doppler, and color Doppler echocardiography were performed. Results were compared with normal values and to mid-term follow-up results.
RESULTS: Rates of reoperation after arterial switch operation and operation to correct concomitant coarctation were 3.3% and 5.1%, respectively. No patient needed medication, and 93.3% had no limitation of physical activity. All children had normal height and weight; 31.6% had abnormal thoracic configuration after median sternotomy. Most patients (91.7%) were in sinus rhythm. Incidence of complete right bundle branch block (10.0%) was unchanged, as was prevalence of ectopic activity (occasional atrial ectopy 20.0%, ventricular ectopy: occasional 21.7%; frequent 1.7%). Left ventricular dimensions and shortening fraction did not change over time. Diameters of neo-aortic valve annulus and neo-aortic root did not increase, and z-scores decreased between mid-term and present evaluation. Incidence of neo-aortic insufficiency was 13.3% and remained unchanged in comparison with the pre-examination value. Neo-aortic stenosis was not seen. Compared with mid-term follow-up, incidence (41.6%) and degree of supravalvular pulmonary stenosis increased.
CONCLUSIONS: Good cardiac results persist 10 years after neonatal arterial switch operation for transposition of the great arteries. Encouraging findings include preservation of left ventricular function, low incidence of rhythm disturbances, lack of further neo-aortic root dilatation, and unchanged incidence of neo-aortic insufficiency compared with mid-term follow-up. Increased incidence and degree of supravalvular pulmonary stenosis are of concern.
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Introduction |
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Patients and methods |
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TopAbstractIntroductionPatients and methodsResultsCommentAcknowledgmentsReferences |
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Forty-six (76.7%) of the 60 patients included in the present study were male and 14 (23.3%) were female. Birth weight ranged from 2.1 to 5.4 kg (3.5 ± 0.5 kg). Forty-seven patients (78.3%) had a simple TGA, 11 (18.4%) had an unimportant VSD that was not closed surgically, and 2 (3.3%) had a VSD closed through the right atrium during ASO. Three patients (5.1%) had a coarctation of the aorta corrected at a later date. Most of the neonates (82%) had undergone balloon atrioseptostomy, and all had been treated with prostaglandin E1 before surgery.
Coronary artery status according to Gittenberger-de Groot and associates [10] was usual (type A I) in 50 (83.3%) of the studied patients. In 3 cases (5.0%), the circumflex coronary artery arose from the right coronary artery (type AB I); in 3 cases (5.0%) right coronary artery and circumflex coronary artery were inverted (type AB II); in 2 (3.3%) a single ostium for the left and right coronary arteries was noted to arise from the right posterior facing sinus (type B I); and in 2 (3.3%) a single ostium for the left and right coronary arteries was noted to arise from the left anterior facing sinus (type A II).
Surgical management
In the study group, the age at ASO ranged from 2 to 39 days (7.1 ± 5.1 days); 2 patients were older than 12 days. Uniform surgery was performed under deep hypothermic circulatory arrest with an esophageal temperature of 14° to 17°C (15.1 ± 1.0°C) and combined low flow cardiopulmonary bypass, as described previously [4]. The coronary arteries were punched out with a button and transplanted into the neo-aortic root with 7.0 PDS. Reconstruction of the coronary artery excision sites was uniform with insertion of two autologous pericardial patches. Direct anastomosis between the distal pulmonary stump and the neopulmonary trunk was performed with 6.0 PDS.
Follow-up study protocol
The 60 unselected patients were evaluated at an age of 7.9 to 14.3 years (10.5 ± 1.6 years). The protocol included an interview with the child and his or her accompanying persons as well as clinical pediatric and cardiological examination performed by 1 pediatric cardiologist.
A 12-lead standard electrocardiogram (ECG) at rest and a 24-hour Holter ECG were performed and analyzed applying generally accepted criteria [11–13]. M-mode, two-dimensional, Doppler, and color Doppler echocardiography were performed with an ATL-HDI 3000 CV unit (Advanced Technology Laboratories, Solingen, Germany). Standard long-axis and 4-chamber views were used to visualize the aorta and the ventricles. Pulsed and continuous wave Doppler were applied to assess valvular competence and to identify obstructions of the great vessels or their branches. Color Doppler was used to examine neo-aortic and neopulmonary insufficiency or intracardiac shunts.
Left heart dimensions and shortening fraction were compared with those of normal children [14]. Neo-aortic diameters were compared with those of normal children [15] and with those of the previous study. Still frames were taken from the parasternal long-axis view at the end of systole. The internal diameter of the valvular annulus was measured at the hinge point of the valve leaflets, the internal diameter of the neo-aortic root at its maximal width.
Doppler peak instantaneous gradients were calculated using the simplified Bernoulli equation. Supravalvular pulmonary stenosis was classified by Doppler gradients as absent (up to 16 mm Hg), trivial (17 to 24 mm Hg), mild (25 to 39 mm Hg), moderate (40 to 59 mm Hg), and severe (more than 59 mm Hg) [16]. Insufficiency of the neo-aortic and neopulmonary valves was quantified by color Doppler as absent, mild (1 to 3 mm diastolic backflow), moderate (4 to 6 mm diastolic backflow), or severe (more than 6 mm diastolic backflow) [17, 18].
Statistical analysis
Results were expressed by the median value and interquartile ranges, assuming nonnormal distribution of the data, or as percentages. The outcome data included both categorical and continuous variables. Fisher exact tests and 
2 tests were used to analyze categorical variables. For comparison of variables at different times of assessment within the study group, the paired nonparametric Wilcoxon test was used. For comparison of variables between subgroups, the nonparametric Mann-Whitney U-test was administered. Neo-aortic diameters were expressed as z-scores. Statistical analysis was performed using the SPSS for Windows software, version 10.0 (SPSS GmbH Software, Munich, Germany). All statistical tests were performed using a significance level of 0.05.
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Results |
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Fifty-six (93.3%) of the 60 patients had no limitation of physical activity (class I according to the New York Heart Association); 4 patients (6.7%) could not be staged because of neurologic impairment (3 patients) and methylphenidate treatment [1], respectively. All patients were without cardiac medication. A detailed report on neurodevelopmental status of the cohort is available in a separate publication [19].
Height and weight of the 60 patients were normal compared with the general population [20]. In contrast, fronto-occipital head circumference was reduced compared with the normal: microcephaly (< 3rd percentile in 3 patients) was due to velo-facio-cardiac syndrome in 1, to embryo-fetal alcohol syndrome in another, and to harmonic somatic developmental delay in the remaining patient (Fig 1). Systolic and diastolic arterial blood pressures at rest were normal in all children. None of the children had clinical signs of cardiac insufficiency.
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Diastolic heart murmurs grade II were noted in 3 patients (5.0%) who had neo-aortic valve regurgitation of mild (n = 1) or moderate (n = 1) degree, or moderate pulmonary insufficiency (n = 1), respectively.
Asymmetry of the right and left hemithoraces with visible prominence of the left ventral ribs was found in 8 (13.3%) of the patients. Eleven patients (18.3%), all without hereditary taint, showed a mild funnel chest. In total, 19 (31.6%) of the patients had a striking thoracic configuration after neonatal median sternotomy. Thoracic deformities were not related to cardiomegaly or surgical technique which was uniform in all patients. Compared with the study 5 years ago, this frequency was significantly higher (p < 0.05), due to an increased occurrence of mild funnel chest. Thoracic abnormalities were of a mild degree, and no patient needed specific orthopedic treatment or physiotherapy.
Surface electrocardiography at rest
Rhythm
Fifty-five of the study patients (91.7%) were in sinus rhythm, 4 (6.7%) had an ectopic atrial rhythm, and 1 (1.7%) a junctional rhythm. One patient without history of tachycardia showed Wolff-Parkinson-White syndrome. Four patients (6.7%) had first-degree heart block. Statistical analysis showed a significantly increased incidence of first-degree heart block compared with the study 5 years ago (Table 1).
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Ventricular hypertrophy
Two patients, 1 with mild aortic insufficiency and 1 with hemodynamically unimportant VSD, both having normal echocardiographic left ventricular dimensions, met ECG criteria for left ventricular hypertrophy. Fourteen patients (23.3%) had signs of right ventricular hypertrophy: 4 patients had mild, 4 had moderate, and 2 had severe supravalvular pulmonary stenosis; 2 additional patients had pulmonary valve insufficiency; in 2 cases, supravalvular pulmonary stenosis was combined with right ventricular outflow tract obstruction. Frequency of right ventricular hypertrophy increased significantly compared with the study 5 years ago and was significantly correlated to the presence of pulmonary stenosis (p = 0.001).
ST-T wave changes
None of the patients (the 6 with complete right bundle branch block excluded) had evidence of ischemia at rest.
Twenty-four-hour ambulatory electrocardiographic monitoring
Rhythm
Sinus or atrial rhythm was present in 58 of 60 patients (96.7%). Two (3.3%) patients had intermittent periods of atrioventricular dissociation and nodal rhythm at rest. Minimal heart rates in these patients were 30 and 36 beats per minute (bpm), respectively (Table 2).
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Rate
The minimal heart rate ranged from 30 to 66 bpm (median 47, interquartile range 6), the maximal heart rate ranged from 70 to 201 bpm (median 153, interquartile range 40). The mean heart rate at sleep (measured during at least 5 sleeping hours) ranged from 33 to 68 bpm (median 49, interquartile range 7). One patient had short sinus pauses (1.9 to 2.3 seconds) during sinus bradycardia at sleep.
Atrial and ventricular ectopy
The prevalence of atrial and ventricular ectopy was not different from the study 5 years ago. Twelve patients (20.0%) had occasional (fewer than 15 per hour) atrial ectopic beats. Episodes of supraventricular tachycardia were not noticed. Ventricular ectopy was present in 13 patients (21.7%). Occasional ventricular ectopic beats (fewer than 30 per hour) were found in 12 patients (20.0%), whereas 1 (1.7%) had frequent (more than 30 per hour) ventricular ectopic beats during exercise. This patient showed monomorphous premature beats from the right bundle branch block type at heart rates higher than 120 bpm. Cardiac catheterization including coronary angiography at age 9.2 years resulted in mild to moderate insufficiency of the quadricuspid aortic valve with normal left ventricular function and no evidence of stenosis, disruption, or obstruction of the coronary circulation.
Echocardiography
Left ventricle
M-mode recordings showed a normal left ventricular end-diastolic diameter in all patients. The shortening fraction ranged from 27% to 47% (median 38%, interquartile range 8%). In 1 patient the shortening fraction was less than 28%. Values did not differ significantly, as compared with the study 5 years ago (Table 3).
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No patient had neo-aortic valve or root stenosis, whereas 3 patients had mild residual aortic isthmic stenosis after surgical correction.
Pulmonary stenosis
Supravalvular pulmonary stenosis was found in 25 (41.6%) of the patients evaluated: 12 (20.0%) trivial, 6 (10.0%) mild, 5 (8.3%) moderate, and 2 (3.3%) severe. In comparison with the study 5 years ago, incidence of supravalvular pulmonary stenosis increased from 30.0% to 41.6% (p = 0.001). Progressive supravalvular pulmonary stenosis during the follow-up period was found in 7 patients (11.7%), 2 of whom (29%) had combined subvalvular or valvular pulmonary stenosis; 5 patients changed from mild to moderate, and 2 patients changed from moderate to severe supravalvular pulmonary stenosis. Incidence and degree of supravalvular pulmonary stenosis were not statistically different if the 2 patients with VSD patch closure were excluded.
Pulmonary insufficiency
Pulmonary valve insufficiency was present in 7 patients (11.7%). It was mild in 6 and of moderate degree in 1 asymptomatic patient. Compared with the study 5 years ago, the rate of pulmonary valve insufficiency increased significantly (p = 0.01).
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Comment |
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TopAbstractIntroductionPatients and methodsResultsCommentAcknowledgmentsReferences |
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General health status
General pediatric health status was good and not different compared with normal children, with the exception of the 4 handicapped patients mentioned above, whereas neurodevelopmental outcome was recently found to be reduced in the same study group [19]. Thoracic abnormalities were frequent with an increased incidence of funnel chest compared with the study 5 years ago [4]. These abnormalities were, however, mild and did not require orthopedic treatment and physiotherapy.
Standard electrocardiographic and holter monitoring
The advantages of anatomic over atrial repair of TGA with respect to preservation of sinus node function have been well documented [9, 22–26]. Our study presents detailed information concerning long-term longitudinal incidence of significant atrial or ventricular rhythm and conduction disturbances after neonatal ASO, based on systematically evaluated standard ECG and Holter monitoring. Sinus rhythm prevailed in the vast majority of patients without change compared with the mid-term follow-up study [4].
Incidence and severity of ventricular ectopy were not significantly increased compared with our results 5 years ago and were less frequent than in children assessed at mean age 2 years after neonatal ASO [2]. Severe ventricular ectopy such as bigeminy, couplets, or runs of ventricular tachycardia may be an indicator for ventricular dysfunction or coronary insufficiency [27].
The persistent low incidence and innocence of atrial arrhythmia in our study underlines the advantages of arterial versus atrial repair in this respect [22–25].
Echocardiography
Left ventricular abnormalities are rare after anatomic correction of TGA. Follow-up periods up to 15 years reveal no evidence of time-related deterioration of left ventricular function [3, 9]. In our series, echocardiographic assessment of left ventricular dimensions and global function confirmed this observation.
Concern has been raised about neo-aortic root dilatation and concomitant aortic regurgitation in children after neonatal ASO [17, 28], as well as about loss of distensibility of the aortic base [29]. A major finding of our present longitudinal study was the observation that neo-aortic valve annulus as well as root diameters did not increase and that their z-scores decreased, compared with the values at mean age 5.3 years. A recent study by Hutter and colleagues [30] provided information about rapid dilatation of the neo-aorta in the first year of life after neonatal ASO, followed by growth toward normalization of the valve and sinus size during childhood, but was not based on repeated echocardiographic measurements in the same patient group. Our results add important information and extend current knowledge with respect to age-dependent development of the neo-aortic root.
In our study group, incidence of neo-aortic valve regurgitation (13.3%) as assessed by color Doppler was similar to that in reports with a mean mid-term follow-up of 5 to 6 years [7, 9]. Compared with the previous mid-term results of the present patient group, rate and degree of neo-aortic valve regurgitation have not significantly increased with age. Mild neo-aortic insufficiency was not found related to the diameter of the neo-aortic valve annulus, but, in contrast to the findings of Hutter and colleagues [30], to the presence of neo-aortic root dilatation. One can speculate that, with further normalization of neo-aortic root diameter with age, incidence of neo-aortic insufficiency might perhaps not increase significantly in the future.
In our study, neo-aortic valve or outflow tract stenoses were not observed, confirming earlier investigations [7, 9, 30]. Until now, reintervention was unnecessary for left ventricular outflow tract stenosis, predicted to occur with a base incidence of 0.1% per year after neonatal ASO [31].
In our study group as in other mid- and long-term reports [1, 9, 31], supravalvular pulmonary stenosis, especially branch pulmonary stenosis, was the most common postoperative complication after ASO. Reintervention rate for right ventricular outflow obstruction (2.6% after 10 years), including stenoses at subvalvular, valvular, and supravalvular sites, however, was less in our patients, compared with other series [7, 20], and comprised half the predicted base incidence of 0.5% reinterventions per year [31]. Supravalvular pulmonary stenosis in our patients is correlated to the prevalence of right ventricular hypertrophy in ECG. As the incidence of supravalvular pulmonary stenosis is dependent on the time of follow-up, on the method of assessment, and also on the definition of "significant" changes, percentages differ considerably in the various studies and range from about 15% to 50%. Although mild systolic gradients in the right ventricular outflow tract are common, the diagnosis of a "severe" supravalvular pulmonary stenosis is rare and ranges from about 2% to 11% [1, 9, 32]. Supravalvular pulmonary stenosis is not uncommonly found associated with growth failure of the valve annulus and pulmonary valve stenosis [32], especially in patients with concomitant aortic isthmic stenosis [33].
Various mechanisms have been implicated in the development of supravalvular pulmonary stenosis. As reported by Williams and coworkers [31] and Wernovsky [33], proximal supravalvular pulmonary stenosis appears to occur early after surgery, related to hypoplasia of the native aortic annulus, and may be reduced by careful sinus reconstruction. However, distal obstruction may occur early and late after surgery, potentially accompanied by growth retardation of the concerned branches, and has been found to be related to certain unusual coronary artery patterns and the technique of surgical coronary sinus reconstruction [33]. In addition, the Lecompte procedure may induce a flattening of the main pulmonary artery with concomitant reduction of its cross-sectional area [34]. In summary, as demonstrated in our study and others, both incidence and severity of supravalvular pulmonary stenosis increase with age; careful further observation is mandatory, especially in the period of rapid somatic growth during adolescence.
In conclusion, the present study highlights persistent encouraging cardiological results 10 years after neonatal ASO for TGA. General health status is excellent in most children. Incidence of surgical or catheter reinterventions and rhythm abnormalities continues to be rare. Late morbidity mainly consists of pulmonary stenosis or neo-aortic insufficiency. Neo-aortic valve and root diameters do not increase and their z-scores decrease in school-aged children, whereas prevalence and degree of neo-aortic valve insufficiency remain stable in our experience. Rate and severity of supravalvular pulmonary stenosis, however, show persistent increase with age and remain a matter of concern.
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