Switch Operation For Complete Transposition Research Articles

Coronary Artery Dimensions on Computed Tomography Following the Neonatal Arterial Switch Operation for the Complete Transposition of the Great Arteries.

Coronary events are life-threatening long-term complications of the arterial switch operation for complete transposition of the great arteries. The aim of our study was to assess the dimensions of the reimplanted coronary arteries and their relationship with the various geometric characteristics to gain a better understanding of the involved mechanisms. Coronary computed tomography angiography (CCTA) scans of 78 asymptomatic pediatric patients were performed at the age of 10.7 (6.3-17.8) years. The position of the ostia, the branching angles, and the diameters of the coronary arteries were determined in a subgroup of 51 patients presenting the usual preoperative coronary anatomy. Mean Z-score of the left main coronary artery (LMCA), left anterior descending coronary artery (LAD), left circumflex coronary artery (LCX), and right coronary artery (RCA) diameters were 0.7 ± 1.2, - 0.4 ± 1.1, - 0.3 ± 1.1, and - 0.3 ± 1.1, respectively. The Z-score of the ostial LMCA diameter had a positive correlation with the remoteness from the main pulmonary artery (p < 0.001) and the branching angle (p = 0.001). The ostial diameter Z-score of the LMCA had a negative correlation with the interval between the arterial switch operation and the CCTA (p = 0.004). Even though most of the coronary diameters fell within the accepted range, which suggests normal overall development, acute branching angle and more anterior origin were associated with smaller ostial coronary artery diameter Z-scores. To prove the clinical relevance of the smaller ostial diameter of high-risk left coronary arteries and the decrease of ostial coronary artery Z-scores over time needs further follow-up studies.

Differential myocardial fibrosis of the systemic right ventricle and subpulmonary left ventricle after atrial switch operation for complete transposition of the great arteries.

This study aimed to assess diffuse myocardial fibrosis of the systemic right ventricle and subpulmonary left ventricle in patients after Senning or Mustard operation for complete transposition of the great artery (TGA) using cardiac magnetic resonance (CMR) T1 mapping. Thirty-one adult TGA patients after Senning (n=24) or Mustard (n=7) operation were studied at the age of 33.3±4.0years. Systemic right ventricular (RV) and subpulmonary left ventricular (LV) volumes, ejection fraction, and myocardial T1 values and extracellular volume fraction (ECV) were determined using CMR. The RV and LV ejection fractions were 47.0±10.9% and 61.3±7.4%, respectively. Compared to published normative values, patients had significantly greater RV and LV native T1 and ECV values (all p<0.001). For each of the basal, mid, and apical segments, the LV native T1 and ECV values were significantly greater in the left than the right ventricle (all p<0.05). There is a significant trend on progressive increase in ECV value from the basal towards the apical segments in both the right (p=0.002) and the left (p<0.001) ventricle. Modestly strong correlations were found between RV and LV native T1 (r=0.60, p<0.001) and ECV (r=0.49, p=0.005) values but not with ejection fractions of the respective ventricles. Differential myocardial fibrosis, with greater involvement of the subpulmonary left ventricle than the systemic right ventricle, is present in patients with TGA after atrial switch operation. Associations between the magnitude of RV and LV fibrosis suggests adverse ventricular-ventricular interaction at the cardiac extracellular matrix level.

Left Ventricular Stiffness in Adolescents and Young Adults After Arterial Switch Operation for Complete Transposition of the Great Arteries.

We tested the hypothesis that left ventricular (LV) myocardial stiffness is altered in patients with transposition of great arteries (TGA) after arterial switch operation (ASO) and explored its associations with myocardial calibrated integrated backscatter (cIB) and LV myocardial deformation. Thirty-one patients and twenty-two age-matched controls were studied. LV myocardial stiffness was assessed by diastolic wall strain (DWS) and stiffness indices including (E/e)/LV end-diastolic dimension, (E/LV global longitudinal early diastolic strain rate)/LV end-diastolic volume, and (E/LV global circumferential early diastolic strain rate)/LV end-diastolic volume, where E and e are early diastolic transmitral and mitral annular velocities, respectively. LV myocardial cIB and longitudinal and circumferential myocardial deformation were determined by conventional and speckle tracking echocardiography. Patients had significantly lower DWS, higher stiffness indices, and greater myocardial cIB than controls (all p < 0.05). The LV longitudinal and circumferential systolic strain and systolic and diastolic strain rates were significantly lower in patients than controls (all p < 0.05). Greater average myocardial cIB was associated with lower DWS (r = - 0.44, p = 0.002). Worse DWS and LV stiffness indices were found to correlate with lower mitral annular systolic velocity, mitral annular late diastolic velocity, and LV longitudinal late diastolic strain rate (all p < 0.05). LV longitudinal and circumferential systolic strain and strain rate were also found to correlate with DWS (all p < 0.05). In conclusion, LV myocardial stiffening occurs in adolescents and young adults with TGA after ASO and is associated with impairment of ventricular systolic and diastolic myocardial deformation and myocardial fibrosis.

Mid-Term Follow-Up after Arterial Switch Operation for Complete Transposition of the Great Arteries

Purpose : Transposition of the Great Arteries has to be surgically corrected by an arterial switch operation. This complex surgical procedure has the potential for significant short- and long-term complications like dilation of the neo-aortic root, coronary and pulmonary artery (PA) stenosis. The aim was to determine a suitable follow-up algorithm for mid-term follow-up. Material and Methods : 26 patients (mean age 10±2 years) were examined using echocardiography, ECG-gated Computed Tomography Angiography (CTA) and functional Magnetic Resonance Imaging (MRI) with flow, cine and pulmonary perfusion measurements. Results : CTA was capable to visualize coronary arteries in all cases. Coronary stenosis did not occur. Echocardiography failed to visualize the coronary arteries in 81%. CTA revealed moderate PA stenosis (25-50% lumen reduction) in 41% and severe stenosis (>50%) in10%. Visualization of pulmonary arteries was possible by echocardiography in only 45%. Correlation between MR-pulmonary perfusion abnormalities and PA stenosis were not present. Doppler-echocardiography showed mild flow acceleration in the main PA (mean pressure gradient 34mmHg) in 4 patients, while MRI found an increased velocity in 9 patients. 10 patients had neo-aortic root dilatation detected with CTA. On echocardiography 8 patients had mild, 4 had moderate aortic valve insufficiency. On MRI amount of aortic valve insufficiency was too small to be quantified. Conclusion : Branch stenosis of the PA was the leading complication 10 years after surgery, coronary stenosis did not occur. Value of Echocardiography is minor in the visualization of coronary arteries and PA morphology and it is recommended only for the assessment of cardiac and valvular function. Additionally, CTA is method of choice for visualization of coronary arteries and PA morphology. In this study the value of MRI for assessment of the complete morphology was limited, but improves with technical advance.

Arterial Mechanics at Rest and During Exercise in Adolescents and Young Adults After Arterial Switch Operation for Complete Transposition of the Great Arteries

We sought to determine the arterial mechanics at rest and during exercise in adolescents and young adults with complete transposition of the great arteries after arterial switch operation and their relations with neoaortic complications. Thirty patients (22 men) aged 16.2 ± 2.1 years and 22 controls (15 men) were studied. Central and peripheral arterial pulse wave velocities, carotid and radial augmentation indices, and central systolic blood pressure (cSBP) were determined by oscillometry and applanation tonometry, whereas arterial dimensions were measured by 2-dimensional echocardiography. Arterial strain, distensibility, and stiffness were determined at rest and during supine bicycle exercise testing. At rest, patients had significantly higher heart-carotid pulse wave velocity, carotid and radial augmentation indices, and cSBP than controls. At rest and during submaximal exercise, patients had significantly lower aortic strain and distensibility, greater aortic and carotid stiffness, and higher SBP than controls. Dilated aortic sinus found in 23 (76.7%) patients was associated with lower aortic distensibility, greater aortic stiffness, and higher cSBP at rest and lower aortic distensibility and strain at submaximal exercise. Significant aortic regurgitation found in 20% (6 of 30) of patients was associated with significantly higher neoaortic z scores. Multivariate analysis identified aortic stiffness at rest (β = 0.46, p = 0.003) and age at operation (β = 0.44, p = 0.004) as significant determinants of aortic sinus z scores. In conclusion, altered mechanics of the central arteries are present at rest and during exercise in adolescents and young adults after arterial switch operation. These findings may have important implications on progression of neoaortic root dilation, exercise recommendations, and medical therapy.

Circulating microRNA expression profile and systemic right ventricular function in adults after atrial switch operation for complete transposition of the great arteries

BackgroundData on the use of circulating microRNAs (miRNAs) as biomarkers of cardiovascular diseases are emerging. Little, however, is known on the expression profile of circulating of microRNAs in congenital heart malformations with a systemic right ventricle that is prone to functional impairment. We aimed to test the hypothesis that circulating miRNA profile is altered in patients late after atrial switch operation for complete transposition of the great arteries (TGA) and further explored possible relationships between alteration of circulating miRNAs and systemic ventricular contractility.MethodsCirculating miRNA expression profiling of serum samples from 5 patients and 5 healthy controls was performed. The results were validated in 26 patients and 20 controls using real-time quantitative reverse-transcription polymerase chain reaction for candidate miRNAs with fold changes >3 by expression profiling. Systemic ventricular myocardial acceleration during isovolumic contraction (IVA) was determined by colour tissue Doppler echocardiography.ResultsCompared with controls, patients had significantly lower systemic ventricular IVA (p = 0.002). Of the 23 upregulated miRNAs identified by profiling, 11 were validated to be increased in patients compared with controls: miR-16, miR-106a, miR-144*, miR-18a, miR-25, miR-451, miR-486-3p, miR-486-5p, miR-505*, let-7e and miR-93. Among the validated 11 miRNAs, miR-18a (r = −0.45, p = 0.002) and miR-486-5p (r = −0.35, p = 0.018) correlated negatively with systemic ventricular IVA for the whole cohort.ConclusionsA distinct serum miRNA expression signature exists in adults with complete TGA after atrial switch operation, with serum miR-18a and miR-486-5p being associated with systemic ventricular contractility.

Circulating Annexin A5 Levels after Atrial Switch for Transposition of the Great Arteries: Relationship with Ventricular Deformation and Geometry

BackgroundInflammatory cytokines, cardiomyocyte apoptosis, and altered collagen turnover may contribute to unfavourable ventricular remodeling. This unfavourable ventricular remodelling is well documented in patients after atrial switch operation for complete transposition of the great arteries. We therefore tested if levels of circulating markers of inflammation, apoptosis, collagen synthesis, and extracellular matrix degradation are altered in patients after atrial switch operation for transposition of the great arteries.Methods and ResultsCirculating tumour necrosis factor (TNF)-α, annexin A5 (AnxA5), carboxy-terminal propeptide of type I procollagen (PICP), amino-terminal propeptide of type III procollagen (PIIINP), matrix metalloproteinase-1 (MMP-1), and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels were determined in 27 patients aged 25.2±3.1 years and 20 controls. Ventricular myocardial deformation and left ventricular eccentricity index (EI) were determined by speckle tracking and two-dimensional echocardiography, respectively. Compared with controls, patients had significantly higher circulating AnxA5 (p<0.001) and TNF-α (p = 0.018) levels, but similar PICP, PIIINP, MMP-1 and TIMP-1 levels. For the whole cohort, plasma AnxA5 correlated with serum TNF-α (p = 0.002), systemic ventricular global longitudinal strain (GLS) and systolic and early diastolic strain rate (all p<0.001), and subpulmonary ventricular GLS and early diastolic strain rate (both p<0.001). In patients, plasma AnxA5 level correlated positively with subpulmonary ventricular EI (p = 0.027). Multiple linear regression analysis identified systemic ventricular GLS (β = −0.50, p<0.001) and serum TNF-α (β = 0.29, p = 0.022) as significant correlates of plasma AnxA5.ConclusionsElevated plasma AnxA5 level in patients after atrial switch operation is associated with impaired systemic myocardial deformation, increased subpulmonary ventricular eccentricity, and increased serum TNF-α level.

Left ventricular contractile reserve after arterial switch operation for complete transposition of the great arteries: an exercise echocardiographic study

This study tested the hypothesis that left ventricular (LV) contractile reserve is altered in patients after arterial switch operation (ASO) for complete transposition of the great arteries (TGA) by non-invasive determination of LV force-frequency relationship (FFR). Thirty-two patients aged 16.2 ± 2.1 years and 22 healthy controls were studied. M-mode parameters, transmitral early (E) and late (A) diastolic velocities, and tissue Doppler-derived systolic (sm), early (em), and late (am) diastolic mitral annular velocities were determined at baseline and during submaximal exercise testing. The LV myocardial isovolumic acceleration (IVA) was measured at different heart rates during exercise for derivation of LV FFR and the average slope of IVA increment with heart rate. At baseline, patients had significantly greater E velocity, E/A and E/em ratios, shorter E deceleration time, and reduced mitral annular sm, em, and am velocities (all P < 0.05), but similar IVA (P = 0.29) compared with controls. During exercise, sm and em remained significantly reduced (P < 0.001), and LV IVA became lower (P < 0.001) in patients. The average FFR slope was significantly lower in patients (0.039 ± 0.019 vs. 0.070 ± 0.024 m/s(2) bpm, P < 0.001). The weighted average FFR curve of patients was flattened compared with the reported positive FFR reference curve based on a healthy paediatric cohort (P < 0.0001). Patients with variant compared with those with usual coronary arterial anatomy had significant flattening of FFR (P < 0.001) and a reduced FFR slope (P = 0.007). In adolescents and young adults after ASO, exercise stress revealed reduced LV contractile reserve, which is worse in those having variant coronary arterial anatomy.

Coronary Diameter and Vasodilator Function in Children Following Arterial Switch Operation for Complete Transposition of the Great Arteries

Coronary Diameter and Vasodilator Function in Children Following Arterial Switch Operation for Complete Transposition of the Great Arteries

Coronary Diameter and Vasodilator Function in Children Following Arterial Switch Operation for Complete Transposition of the Great Arteries

Coronary reimplantation during arterial switch operation (ASO) may affect coronary artery growth and function during childhood. The purpose of this study was to assess coronary artery diameter and regional myocardial blood flow (MBF) and myocardial flow reserve (MFR) in children after neonatal ASO. We measured proximal diameters of left anterior descending (LAD), left circumflex, and posterior descending coronary arteries on coronary angiogram in 12 children (median age 11 years, range 7.6 to 15.1) with a history of neonatal ASO. These children then underwent cardiac positron emission tomographic imaging using nitrogen-13 ammonia to assess MBF at baseline and during intravenous adenosine hyperemia in regions supplied by these 3 coronary arteries. Coronary artery z-scores were within normal range (-2.0 to 2.0) for 32 of 36 coronary arteries. MFR (ratio of hyperemic to basal MBF) was normal (>2.5) in all myocardial regions in 10 of 12 patients. The remaining 2 patients, 1 with a dual LAD and 1 with LAD origin from the right coronary artery, had generalized impairment of hyperemic MBF (<2.0 ml/g/min) and low MFR (<2.5). Coronary artery z-scores and MFR in corresponding myocardial territories were not correlated (r = 0.15, p = 0.36). In conclusion, coronary growth and function appear to be normal in most children after neonatal ASO. Children with anatomic LAD abnormalities may be at increased risk of impaired MFR.

The significance of pulmonary annulus size in the surgical management of transposition of the great arteries with ventricular septal defect and pulmonary stenosis

Aortic translocation has received growing attention in the management of complete transposition with ventricular septal defect and pulmonary stenosis, but the criteria regarding pulmonary stenosis for selecting this option have yet to be established. The aim of this study is to evaluate the significance of pulmonary annulus size with the outcome after the arterial switch operation. Between November 1996 and September 2008, 250 patients underwent the arterial switch operation for complete transposition. Among them, 8 patients with a pressure gradient greater than 30 mm Hg, bicuspid pulmonary valve, and an aortic Z-score of the pulmonary annulus less than 0 were included in this retrospective study. The median age was 19.1 months (range, 0.5-80.0 months). The median follow-up was 39.7 months (range 9.1-139.5 months). At latest follow-up, the Z-score of the neoaortic annulus increased from -1.50 + or - 1.13 (range, -3.42 to -0.35) to 1.10 + or - 1.15 (range, -0.8 to 2.10) (P < .01). No patient had a significant pressure gradient across the left ventricular outflow tract. There was 1 early death and there were no late deaths. Two reoperations were performed in 1 patient for neoaortic stenosis at 81 months and 110 months after the operation. Latest echocardiogram revealed grade 0 or 1 neoaortic insufficiency. It was possible to extend the indication for the arterial switch operation with acceptable outcome to the patient with a Z-score of about -3 of the pulmonary annulus despite bicuspid pulmonary valve. Inasmuch as the arterial switch operation has benefits over the other options, a large-scale study is required for more reasonable triage in this group of patients.

Diastolic Biventricular Impairment at Long-term Follow-up After Atrial Switch Operation for Complete Transposition of the Great Arteries: An Exercise Tissue Doppler Echocardiography Study

The aim of this study was to investigate regional myocardial function after atrial switch operation for transposition of the great arteries (TGA) using tissue Doppler echocardiography with strain rate (SR) imaging. In all, 24 patients with TGA aged 12 to 33 years and 10 control subjects underwent tissue Doppler echocardiography/SR imaging at rest and during bicycle exercise at 1 and 2 W/kg. Longitudinal function was quantified by strain, SR, and peak velocities measured in the free wall of the systemic ventricle, in septum and in the lateral wall of the subpulmonary ventricle. In patients with TGA, both ventricles showed reduced peak systolic SR values at rest. The increase in peak early diastolic velocity with exercise was reduced in the systemic ventricle (-47 +/- 23 mm/s at rest to -73 +/- 35 mm/s at 2 W/kg, P < .05) and absent in the subpulmonary ventricle (-78 +/- 38 mm/s at rest to -75 +/- 19 mm/s at 2 W/kg) of patients with TGA. Exercise tissue Doppler echocardiography/SR imaging identified severely reduced relaxation reserve of both ventricles as typical feature of myocardial dysfunction after atrial repair for TGA.

Half-turned truncal switch operation for complete transposition of the great arteries with ventricular septal defect and pulmonary stenosis

J Thorac Cardiovasc Surg 2003;125:966-8

Excellent Survival and Low Complication Rate in Medium-Term Follow-Up after Arterial Switch Operation for Complete Transposition

Objective—To determine medium-term outcome after arterial switch operation for complete transposition in a population-based cohort.Design—Retrospective study of all 86 patients operated on at our institution from 1982 to 2000. Age at operation was 0-256 days (median 6 days); 28 (32%) had closure of a ventricular septal defect, 2 of whom had double outlet right ventricle. Additional surgery included coarctectomy in three, pulmonary artery banding in two and atrial septectomy in one patient.Results—Thirty-day operative mortality was 7/86 (8.1 %), after 1988 mortality was only 3.8% and confined to patients with unusual coronary artery patterns. There was no late mortality; Kaplan-Meier survival was 91 %. Five patients (6% of survivors) were reoperated for right ventricular outflow tract obstruction. At last follow-up, 86% were free from complications; three had neurological complications, two were on treatment for ventricular dysfunction and one had a pacemaker for postoperative atrioventricular block.Conclusion—In this cohort of first-generation patients treated with arterial switch operation, medium-term survival is excellent and the rate of reoperation and sequelae is low.

Late outcome after arterial switch operation for complete transposition of great arteries with left ventricular outflow tract obstruction

Background Long-term follow-up of patients who underwent arterial switch operation for complete transposition of great arteries with anatomic left ventricular outflow tract obstruction (LVOTO) has rarely been brought into the focus. Methods Of 299 patients who underwent an arterial switch operation between January 1991 and January 2001, 23 patients had anatomic LVOTO. Age ranged from 4 days to 18 years (median 90 days) and weight ranged from 2.6 to 35 kg (median 4.3 kg). Surgical management included arterial switch operation, closure of ventricular septal defect wherever indicated, and excision of LVOTO. Results Among patients with preoperative LVOTO there were 2 early deaths and 8 patients had mild neoaortic regurgitation at the time of discharge. Follow-up ranged from 8 months to 9 years (mean 60 ± 12 months). In 4 patients who had mild neoaortic regurgitation at discharge, the regurgitation progressed to moderate or severe degree after a follow-up of 22 to 72 months. In 1 patient mild mitral regurgitation present at the time of discharge progressed to severe mitral regurgitation. This patient subsequently underwent double valve replacement. Conclusions Presence of preoperative anatomical LVOTO in patients undergoing arterial switch operation predicts high incidence of postoperative neoaortic regurgitation.

Neurodevelopmental outcome related to cerebral risk factors in children after neonatal arterial switch operation

Background. Neurodevelopmental outcome after neonatal arterial switch operation for complete transposition of the great arteries is an important topic needing prospective assessment. Methods. A group of 33 unselected children (3.0 to 4.6 years) operated on as neonates with combined deep hypothermic circulatory arrest and low flow cardiopulmonary bypass and a control group of 32 age-matched healthy children (3.0 to 4.8 years) underwent evaluation of socioeconomic and clinical neurological status and a standardized test comprising all areas of child development. Results of patients were related to those of the control group, to population norms, and to preoperative, perioperative, and postoperative cerebral risk factors. Results. Clinical neurological status was normal in 26 patients (78.8%) and reduced in 7 (21.2%). Complete developmental score and the subscores for motor function, visual perception, learning and memory, cognitive function, language, and socioemotional functions were not different compared to population norms. Compared to the patients, the children of the control group scored higher on tests of complete development, cognition, and language, but also on socioeconomic status. Complete developmental score and the scores for motor, cognitive, and language functions were weakly inversely related to the duration of circulatory arrest, but not to the duration of bypass. Cerebral risk factors such as serum levels of the neuron-specific enolase, perinatal acidosis, perinatal asphyxia, peri- and postoperative cardiocirculatory insufficiency, or clinical seizures were not correlated to the test results. Conclusions. Neonatal arterial switch operation with combined circulatory arrest and low flow bypass is associated with neurological impairment, but not with reduced development as assessed by formal testing of motor, cognitive, language, and behavioral functions. Perioperative serum level of the neuron-specific enolase is not a valid marker for later developmental impairment.

Long-term assessment and serial evaluation of cardiorespiratory exercise performance and cardiac function in patients with atrial switch operation for complete transposition

At present, a considerable number of patients survive who underwent an atrial switch operation for correction of complete transposition. Our study aimed to assess their long-term exercise performance and the serial evolution of cardiac function. We studied 22 patients 5 to 17 years after an atrial switch operation, and followed them serially for 3.5 +/- 2 years after the first evaluation. Cardiorespiratory exercise function was assessed by analysis of gas exhange and by determination of the ventilatory anaerobic threshold. Echocardiography was performed on all evaluations. All patients were in Class I of the classification of the New York Heart Association at all assessments. Ventilatory anaerobic threshold, however, was significantly lower than normal. It averaged 77.9% +/- 13.7 of the normal mean value at the initial evaluation, and remained stable when re-evaluated later (76.2 +/- 13.7%). At the initial study, the increase in oxygen uptake during graded exercise was below the 95% confidence limit in 6 of the patients, and was below this level in 10 patients at re-assessment. The subnormal values for oxygen uptake during submaximal exercise were associated with moderate to severe haemodynamic dysfunction. At echocardiography, 15 of 17 patients studied twice had mild to moderate right ventricular dilation and tricuspidregurgiation, which remained virtually the same at reasssesment. A stable sinus rhythm was initially present in 17 patients, and persisted in 15 patients during follow-up. At medium term follow-up, cardiorespiratory exercise performance remains stable in patients after atrial switch repair. Serial exercise testing appears useful, because in individual patients in the present study, a decreasing exercise tolerance correlated with development of haemodynamic sequels.

Sympathetic denervation and reinnervation after arterial switch operation for complete transposition.

Sympathetic cardiopulmonary nerves arise from the cervical sympathetic trunks and the stellate ganglia and subsequently course along the origin of the great arteries and the coronary arteries to innervate the ventricles. Therefore, the sympathetic nerves may be obligatorily interrupted by the arterial switch operation (ASO) for complete transposition of the great arteries. To demonstrate and characterize the possible sympathetic denervation, 51 patients after ASO, 4.8 years old (range, 1 month to 10.1 years), underwent [123I]metaiodobenzylguanidine (MIBG) imaging of the sympathetic nerve terminal. MIBG uptake to the heart was graded by quantitative analysis using the heart-to-mediastinum (H/M) ratio of MIBG uptake. A quantitative criterion for absent uptake of MIBG was set to 1.48 in the H/M ratio. Four patients < 1 month after ASO showed complete absence of MIBG uptake, which had been observed preoperatively. In contrast, 47 patients late after ASO (range, 15 months to 10.1 years) showed various degrees of uptake of MIBG. Patients operated on at < or =55 days of age showed positive MIBG uptake much more frequently than those operated on at later ages. Heart rate and rate-pressure product at peak exercise on a treadmill exercise test were significantly greater in patients with positive uptake than in those with absent uptake of MIBG. Cardiac sympathetic nerves were denervated early after and reinnervated late after ASO. Neonatal ASO may be favorable to facilitate sympathetic reinnervation, which may affect exercise tolerance late after surgery.

Follow-up Study after Atrial Switch Operation for Complete Transposition of the Great Arteries

Background:Since the introduction of atrial switch operation, the outlook for patients with complete transposition of the great arteries (TGA) has improved dramatically. However, many survivors are afflicted with postoperative complications and continue to demand medical attention. We therefore performed the study for the evaluation of the clinical course in the patients with complete TGA after atrial switch operation. Methods:We analyzed the data of 51 patients who underwent the atrial switch operation for complete TGA at Seoul National University Hospital between January 1981 and June 1993 retrospectively. Results:The patients were composed of 36 males and 15 females (mean age at operation, 15±30 months, range 2 months18 years). Senning operation was undertaken in 43 and Mustard operation in 8. Among these, 27 had simple and 24 complex complete TGA. The early mortality rate within 1 month postoperatively was 39% and the late mortality rate 16%. The actuarial survival rate after 10 years was 78%. Of these, 17 cases have been followed up so far. Although the significant tricuspid regurgitation was noted in 9, right ventricular systolic function was maintained in all of them. Preoperative sinus node dysfunction was noted in 1 case. Postoperatively, premature ventricular contractions were found in 8 cases, atrial flutter in 4, and sinus node dysfunction in 7. Subclinical pulmonary venous obstruction was found in 2 and systemic venous obstruction in 1. At present, one takes digoxin for prevention of atrial flutter and 7 take digoxin, furosemide, and/or angiotensin-converting enzyme inhibitors for prevention of ventricular functional deterioration. Twelve cases were in New York Heart Association functional class I at the latest follow-up and 5 were in class II. Conclusion:This study revealed that morbidity and mortality were not low after atrial switch operation. However, considering the good longterm functional status in the survivors, atrial switch operation could be an alternative to arterial switch operation in complicated cases of TGA. (Korean Circulation J 1998;28(4):683-690)

Small Left Coronary Arteries After Arterial Switch Operation for Complete Transposition

Background. Myocardial perfusion is not completely normal and ventricular function is depressed in some patients after the arterial switch operation. The basic mechanism has not yet been defined totally. Methods. The diameters of the right, left main trunk, anterior descending, and circumflex coronary arteries were measured by computer-assisted densitometry at 8 to 86 months (mean, 47.5 months) after the arterial switch operation in 86 patients. Results. The Z scores, compared with control, were +2.0 ± 0.3, −1.8 ± 0.3, and −1.5 ± 0.3 for the right, left anterior descending, and circumflex coronary arteries, respectively. The Z score for the total cross-sectional area of the three vessels was −1.5 ± 0.3. These parameters did not correlate with left ventricular ejection fraction. Conclusions. At the midterm follow-up after the arterial switch operation for complete transposition of the great arteries, the left coronary arteries are small. A careful follow-up study is mandatory to clarify the clinical significance of this finding.