Arrhythmias and intracardiac conduction after the arterial switch operation

Prenatal Delineation of Coronary Anatomy in Dextro-Transposition of Great Arteries

Background

Dextro-transposition of the great arteries (D-TGA) is the second-most common cyanotic congenital heart disease with variable coronary artery anatomy. The arterial switch procedure has revolutionized outcomes for this defect, with coronary anatomy being a key determinant of both short- and long-term outcomes following surgical repair. The assessment of coronary anatomy is usually undertaken in the postnatal period by transthoracic echocardiography, with assessment prenatally not being well studied. We sought to assess the feasibility of delineating the coronary arteries on fetal echocardiograms in a small cohort of patients followed prenatally.

Methods

This was a retrospective review of fetuses with D-TGA from 2008 to 2018. Patients with prenatal diagnosis of D-TGA were reviewed for the assessment of coronary artery anatomy. Details of coronary artery anatomy diagnosed prenatally were compared with postnatal transthoracic echocardiograms and intraoperative findings.

Results

Thirty-four fetuses with findings of D-TGA on prenatal echocardiograms were reviewed. 14/34 fetuses had attempted delineation of coronary artery anatomy, with average gestational age of 28 weeks (range 23-31 weeks) at the time of diagnosis. Two-dimensional and color Doppler imaging of the coronary arteries on both short and long axis images were performed, with complete delineation being possible in ~ 86% of fetuses. These findings were confirmed postnatally.

Conclusions

Fetuses with D-TGA can have variable coronary artery anatomy which drives postnatal outcomes. Our study describes a cohort of patients with D-TGA wherein coronary artery anatomy was assessed. We demonstrate that coronary artery evaluation is feasible prenatally with optimal imaging techniques, being more successful after 25 weeks' gestation. The potential knowledge of dangerous variants can help with referral to centers of excellence for appropriate postnatal management and facilitate prenatal care accordingly.

Tachyarrhythmia as a possible symptom of coronavirus in a neonate diagnosed with transposition of the great arteries

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic poses broad challenges to healthcare systems and providers. The manifestations of this disease are still being described in a variety of different contexts and patient populations.

RESULTS

We report the case of a neonate who demonstrated COVID-19 after surgical correction of transposition of the great arteries. In addition, the patient demonstrated an evolving and persistent tachyarrhythmia consistent with neither the most likely postoperative complications nor typical COVID-19.

DISCUSSION

The patient had negative preoperative testing for the virus and presented with profound oxygen desaturation and respiratory failure several days postoperatively. This raised concern for a complication of his arterial switch operation. It was found that one of the patient's caregivers was an asymptomatic carrier of COVID-19, and imaging ruled out intracardiac shunting. After initiating treatment for COVID-19, the patient's oxygen requirements and need for anti-arrhythmic agents improved.

CONCLUSION

We propose that, despite negative preoperative testing, coronavirus infection may present as refractory tachyarrhythmia, and may be considered along with surgical complications as a cause for unexplained hypoxemia postoperatively.

Management considerations in the adult with surgically modified d-transposition of the great arteries

Dextro-transposition of the great arteries (D-TGA) has undergone a significant evolution in surgical repair, leading to survivors with vastly different postsurgical anatomy which in turn guides their long-term cardiovascular morbidity and mortality. Atrial switch repair survivors are limited by a right ventricle in the systemic position, arrhythmia and atrial baffles prone to obstruction or leak. Functional assessment of the systemic right ventricle is complex, requiring multimodality imaging to include specialised echocardiography and cross-sectional imaging (MRI and CT). In the current era, most neonates undergo the arterial switch operation with increasing understanding of near-term and long-term outcomes specific to their cardiac anatomy. Long-term observations of the Lecompte manoeuvre or coronary stenoses following transfer continue, with evolving understanding to improve surveillance. Ultimately, an understanding of postsurgical anatomy, specialised imaging techniques and interventional and electrophysiological procedures is essential to comprehensive care of D-TGA survivors.

Development of quality metrics for ambulatory pediatric cardiology: Transposition of the great arteries after arterial switch operation

OBJECTIVE

To develop quality metrics (QMs) for the ambulatory care of patients with transposition of the great arteries following arterial switch operation (TGA/ASO).

DESIGN

Under the auspices of the American College of Cardiology Adult Congenital and Pediatric Cardiology (ACPC) Steering committee, the TGA/ASO team generated candidate QMs related to TGA/ASO ambulatory care. Candidate QMs were submitted to the ACPC Steering Committee and were reviewed for validity and feasibility using individual expert panel member scoring according to the RAND-UCLA methodology. QMs were then made available for review by the entire ACC ACPC during an "open comment period." Final approval of each QM was provided by a vote of the ACC ACPC Council.

PATIENTS

Patients with TGA who had undergone an ASO were included. Patients with complex transposition were excluded.

RESULTS

Twelve candidate QMs were generated. Seven metrics passed the RAND-UCLA process. Four passed the "open comment period" and were ultimately approved by the Council. These included: (1) at least 1 echocardiogram performed during the first year of life reporting on the function, aortic dimension, degree of neoaortic valve insufficiency, the patency of the systemic and pulmonary outflows, the patency of the branch pulmonary arteries and coronary arteries, (2) neurodevelopmental (ND) assessment after ASO; (3) lipid profile by age 11 years; and (4) documentation of a transition of care plan to an adult congenital heart disease (CHD) provider by 18 years of age.

CONCLUSIONS

Application of the RAND-UCLA methodology and linkage of this methodology to the ACPC approval process led to successful generation of 4 QMs relevant to the care of TGA/ASO pediatric patients in the ambulatory setting. These metrics have now been incorporated into the ACPC Quality Network providing guidance for the care of TGA/ASO patients across 30 CHD centers.

Adaptation of Radiology Software to Improve Cardiology Results Reporting

Objective: Twenty-four hour ambulatory electrocardiograms (“Holter” monitors) are a key diagnostic test in cardiology. Commercial electronic medical record (EMR) tools have not been designed for pediatric Holter monitor reporting and paper-based methods are inefficient.

Methods: Our tertiary pediatric hospital adapted a radiology EMR tool to a cardiology workflow in order to report Holter monitor results. A retrospective review was performed at 4 time points: prior to intervention, immediately post-intervention, at 6 months and at 12 months post-intervention. The primary outcome variable was time to reporting of Holter findings.

Results: Holter reports were reviewed on 527 studies (patient ages: 1 day to 42 years). The time between the date the patient returned the Holter monitor until the date the referring physician received a final report improved from 19.8 days to 1.5 days (p<0.001). This result was durable over the next 12 months of follow-up. Physician interpretation time improved from 2.1 days to 0.6 days (p=0.01). Transcriptionist time and result scanning time were eliminated (removing 1.9 days and 14 days from the workflow, respectively).

Conclusion: EMR systems are not typically designed for pediatric cardiology, but existing systems can be adapted, yielding important gains for patient care. In specialties like pediatric cardiology, there is insufficient volume nationally to drive development of commercial systems. This study demonstrates the general principle that creative adaptation of EMR systems can improve result reporting in pediatric cardiology and likely in other cardiology practices.

Citation: Webster G, Ward K, Deal BJ, Anderson JB, Tsao S. Adaptation of Radiology Software to Improve Cardiology Results Reporting. Appl Clin Inform 2017; 8: 936–944 https://doi.org/10.4338/ACI-2017-03-RA-0051

Pacing and Defibrillators in Complex Congenital Heart Disease

Device therapy in the complex congenital heart disease (CHD) population is a challenging field. There is a myriad of devices available, but none designed specifically for the CHD patient group, and a scarcity of prospective studies to guide best practice. Baseline cardiac anatomy, prior surgical and interventional procedures, existing tachyarrhythmias and the requirement for future intervention all play a substantial role in decision making. For both pacing systems and implantable cardioverter defibrillators, numerous factors impact on the merits of system location (endovascular versus non-endovascular), lead positioning, device selection and device programming. For those with Fontan circulation and following the atrial switch procedure there are also very specific considerations regarding access and potential complications. This review discusses the published guidelines, device indications and the best available evidence for guidance of device implantation in the complex CHD population.

Outcomes after Arterial Switch Operation for Simple Transposition

Without intervention, babies born with transposed great arteries (TGA) are doomed to a rapid death. Jatene and coworkers deserve the credit for performing the first successful arterial switch operation (ASO) in a patient with TGA and ventricular septal defect (VSD) in 1975. Since then ASO has become the procedure of choice in most medical centers. This review article summarizes the historical aspects of arterial switch operation and assesses this procedure's outcomes.

Arrhythmias in the paediatric intensive care unit: a prospective study of the rates and predictors of arrhythmias in children without underlying cardiac disease

OBJECTIVE

Arrhythmias are common in patients admitted to the paediatric intensive care unit. We sought to identify the rates of occurrence and types of arrhythmias, and determine whether an arrhythmia was associated with illness severity and paediatric intensive care unit length of stay.

DESIGN

This is a prospective, observational study of all patients admitted to the paediatric intensive care unit at the Children's Hospital at Montefiore from March to June 2012. Patients with cardiac disease or admitted for the treatment of primary arrhythmias were excluded. Clinical and laboratory data were collected and telemetry was reviewed daily. Tachyarrhythmias were identified as supraventricular tachycardia, ventricular tachycardia, and arrhythmias causing haemodynamic compromise or for which an intervention was performed.

RESULTS

A total of 278 patients met the inclusion criteria and were analysed. There were 97 incidences of arrhythmia in 53 patients (19%) and six tachyarrhythmias (2%). The most common types of arrhythmias were junctional rhythm (38%), premature atrial contractions (24%), and premature ventricular contractions (22%). Tachyarrhythmias included three supraventricular tachycardia (50%) and three ventricular tachycardia (50%). Of the six tachyarrhythmias, four were related to placement or migration of central venous lines and two occurred during aminophylline infusion. Patients with an arrhythmia had longer duration of mechanical ventilation and paediatric intensive care unit stay (p<0.001). In multivariate analysis, central venous lines (odds ratio 3.1; 95% confidence interval 1.3-7.2, p=0.009) and aminophylline use (odds ratio 5.1; 95% confidence interval 1.7-14.9, p=0.003) were independent predictors for arrhythmias.

CONCLUSIONS

Arrhythmias were common in paediatric intensive care unit patients (19%), although tachyarrhythmias occurred rarely (2%). Central venous lines and use of aminophylline were identified as two clinical factors that may be associated with development of an arrhythmia.

Ablation of Arrhythmias in Patients with Adult Congenital Heart Disease

Arrhythmias in adults with congenital heart disease, most commonly related to previous surgical procedures, are a frequent comorbidity in this growing population thanks to the improved outcome of surgical techniques. Re-entrant circuits around areas of scarring and natural barriers, combined with abnormal haemodynamics and the underlying anatomy, are the most common cause for these arrhythmias. They are often poorly tolerated and medical treatment is frequently inadequate. In recent years, catheter ablation has emerged as a successful therapeutic option. New advanced techniques such as the use of modern three-dimensional (3D) navigation systems have contributed to better understanding of the arrhythmia mechanisms and higher success rates of the ablation procedures. In this article we briefly summarise the characteristics of the most common arrhythmias in this patient population and some key aspects in their treatment by catheter ablation.

Tachyarrhythmias and catheter ablation in adult congenital heart disease

Advances in surgical technique have had an immense impact on longevity and quality of life in patients with congenital heart disease. However, an inevitable consequence of these surgical successes is the creation of a unique patient population whose anatomy, surgical history and haemodynamics result in the development of a challenging and complex arrhythmia substrate. Furthermore, this patient group remains susceptible to the arrhythmias seen in the general adult population. It is through a thorough appreciation of the cardiac structural defect, the surgical corrective approach, and haemodynamic impact that the most effective arrhythmia care can be delivered. Catheter ablation techniques offer a highly effective management option but require a meticulous attention to the real-time integration of anatomical and electrophysiological information to identify and eliminate the culprit arrhythmia substrate. This review describes the current approach to the interventional management of patients with tachyarrhythmias in the context of congenital heart disease.

Adenosine stress myocardial perfusion scintigraphy in pediatric patients after arterial switch operation

Context:

Arterial switch operation (ASO) has become the established treatment for correction of transposition of great arteries (TGA). Despite the immediate correction of abnormal hemodynamics, acute and delayed complications related to the coronaries may cause morbidity and mortality.

Aims:

We evaluated the incidence of perfusion abnormalities and safety of adenosine by stress–rest myocardial perfusion single-photon emission computed tomography (SPECT) [myocardial perfusion scintigraphy (MPS)] using Tc-99m Sestamibi (MIBI) in asymptomatic children post-ASO.

Settings and Design:

Prospective study.

Materials and Methods:

We conducted a prospective, single-institutional study where stress–rest MPS was performed on 10 children of age between 1.25 and 6 years. Two of the patients had additional ventricular septal defect, one patient had left ventricular outflow tract obstruction, and another had Taussig–Bing anomaly. All the patients underwent corrective surgery as a single-stage procedure at the age of 176 ± 212 days (range 9-560 days). Adenosine was administered at a rate of 140 μg/kg/min intravenously as continuous infusion for duration of 6 min.

Statistical Analysis Used:

All the continuous variables were summarized as mean ± standard deviation, or range and median. Mann–Whitney test for unpaired data and Wilcoxon Rank test for paired samples were used.

Results:

The average increase in heart rate over the basal heart rate after adenosine stress was 59.7 ± 17.0%. No acute or remote complications were observed in any case. None of the patients demonstrated myocardial perfusion defects, either at rest or after adenosine stress.

Conclusions:

MPS post-adenosine induced vasodilatation is safe and feasible in patients of ASO for transposition of great arteries. One-stage repair, implantation of excised coronary buttons within neo-aortic sinus, and minimal or no mobilization of proximal coronaries may eliminate the occurrence of perfusion defects in patients of corrected TGA.

Anesthetic management of a child with corrected transposition of great vessels undergoing non-cardiac surgery

We describe the successful anesthetic management of a 14-year-old child, a corrected case of transposition of great vessels in childhood and presently with residual atrial septal defect, peripheral cyanosis, and neurological deficit of lower limb presented for tendoachillis lengthening.

Magnesium supplementation reduces postoperative arrhythmias after cardiopulmonary bypass in pediatrics: a metaanalysis of randomized controlled trials

Postoperative arrhythmia (POA) is the most common complication encountered after cardiopulmonary bypass (CPB). The preventive effect of magnesium in POA has been confirmed by metaanalyses in adults, but less is known in pediatric patients. A metaanalysis of published trials was conducted to examine the efficacy of magnesium supplementation in POA prevention among pediatric patients undergoing CPB. Relevant trials were identified from electronic databases (Medline, Embase, Web of Science, and Cochrane library). Pooled relative risk (RR) and 95 % confidence intervals (CI) were calculated using Mantel-Haenszel random-effects models, and heterogeneity was determined qualitatively according to I (2) and chi-squared statistical analyses. Among 121 potentially relevant studies, five randomized controlled trials met the inclusion criteria, resulting in a pooled total of 348 participants. Compared with placebo, magnesium supplementation decreased the incidence of arrhythmia after CPB in pediatric patients by 66 % (RR, 0.34; 95 % CI, 0.18-0.65; P = 0.001), with no heterogeneity between trials (heterogeneity P = 0.68; I (2) = 0 %). Magnesium supplementation significantly reduces the incidence of postoperative arrhythmias in pediatric patients undergoing CPB. Although the findings encourage the use of magnesium as an alternative to postoperative arrhythmias after CPB in pediatric patients, higher-quality randomized clinical trials are necessary before the findings can be generalized.

Late arrhythmias after surgery for transposition of the great arteries

The evolution of surgical techniques for transposition of the great arteries (TGA) provides a moving target for the assessment of late arrhythmias. Imposed on varying anatomical substrates are progressive surgical interventions, each with its own set of sequelae. Analysis of the risk of arrhythmia development requires division into which arrhythmia is present, for which form of transposition, undergoing what type of surgery, and in which surgical era. For purposes of this review, available data on d-TGA undergoing Senning repairs, Mustard repairs, and arterial switch repairs and congenitally corrected TGA undergoing double switch repairs are reviewed.

Arrhythmia management in patients with a common arterial trunk and d-transposition of the great arteries

Arrhythmias in patients with congenital heart disease present a challenge to the care of these patients and can result in significant morbidity and mortality. Transposition of the great arteries and common arterial trunk are no exceptions. It is important to identify risk factors for arrhythmia development in the peri-operative period. The peri-operative arrhythmia burden may relate to the underlying congenital heart disease, haemodynamic perturbations, operative events, and potential residual lesions. In addition, these patients are at risk for developing arrhythmias later in life, and non-invasive and potentially invasive arrhythmia surveillance should be a routine part of the care of these patients. This article highlights important strategies to manage arrhythmia development and prevention in this patient population.

Managing arrhythmias before and after aortic valve surgery in children

The proximity of the coronary arteries and the bundle of His to the aortic valve may contribute to the pathogenesis of arrhythmias in patients with aortic valve disease. Severe aortic valve disease may also adversely alter left ventricular hemodynamics (end-diastolic dimensions and wall stress) and thus create a substrate for ventricular arrhythmias before any intervention is performed. The severity of these arrhythmias depends on the severity of the underlying substrate (or the specific problem, such as aortic stenosis or aortic regurgitation), the age at which the aortic valve intervention was performed, the type of intervention (i.e. transcatheter aortic valve interventions or open aortic valve replacement or repair), and the reversibility of the altered hemodynamics after surgery. Both bradyarrhythmias and tachyarrhythmias are known complications of aortic valve interventions. Although data are scant, this review summarizes the incidence of arrhythmias before and after aortic valve interventions from a pediatric perspective.

Late Atrio-ventricular Block After Arterial Switch for D-transposition of the Great Vessels With Intact Interventricular Septum

Arterial switch operation for transposition of the great arteries without ventricular septal defect usually does not lead to atrio-ventricular conduction disturbances. We discuss the case of a young boy presenting with first and second degree supra hisian atrio-ventricular block late after switch operation.

Emergency diagnosis and management of pediatric arrhythmias

True emergencies due to unstable arrhythmias in children are rare, as most rhythm disturbances in this age group are well-tolerated. However, presentation to an emergency department with symptoms of palpitations, fatigue and/or syncope is much more common. Sinus tachycardia is by far the most commonly reported arrhythmia, followed by supraventricular tachycardia. Emergency physicians should be prepared for diagnosis and to acutely manage various types of arrhythmias seen in children, to assess the need for further diagnostic testing, and to determine whether cardiology evaluation and follow-up are needed. This article is intended to provide diagnostic and management guidelines of the most common types of arrhythmias seen in children with structurally normal hearts as well as those associated with congenital heart disease and cardiomyopathies.

Arrhythmias in patients with hypoplastic left heart syndrome

BACKGROUND

Mortality between stage I and II palliation for hypoplastic left heart syndrome (HLHS) has been associated with arrhythmias. The stage-related proportion, associations, and clinical impact of arrhythmias in patients with HLHS have not been evaluated. In addition, arrhythmia subtypes have not been described in this patient group.

METHODS

We performed a retrospective analysis of all patients at Duke University Medical Center who received one or more palliative stages for HLHS from September 2000 to October 2008.

RESULTS

Overall, 49 (57%) of 86 patients had 63 arrhythmias. The majority of arrhythmias occurred between stage I and II, with 44 (51%) of 86 patients manifesting a new arrhythmia. Arrhythmias occurring in this interval tended to be associated with a higher mortality compared with arrhythmias occurring after stage II (odds ratio = 3.2 [95% CI 0.84-12.0], P = .09). Overall mortality was similar in patients with and without arrhythmias (P = .99). Supraventricular tachycardia was the most common arrhythmia (16/63; 25%), but persistent bradycardias (sinus node dysfunction or high-grade atrioventricular block) had the worst clinical outcome with 73% mortality (8/11). There was no association between arrhythmia occurrence and degree of tricuspid regurgitation, left ventricular hypertension, genetic syndrome, type of stage I operation, or need for extracorporeal membrane oxygenation.

CONCLUSIONS

A large proportion of patients with HLHS experience serious arrhythmias requiring therapy, especially between stage I and II. Persistent bradycardia following stage I is associated with a high mortality rate. Considering all arrhythmia patients, overall mortality was not different compared with the arrhythmia-free group.

Late Complications Following the Arterial Switch Operation

The arterial switch operation has been the principal treatment for transposition of the great arteries and its variants for the last 25 years. Early mortality has decreased significantly over time, but long-term complications include pulmonary artery stenosis, coronary artery obstruction, neoaortic valvar insufficiency, arrhythmia, and aortic arch obstruction. This article provides an overview of the history, anatomic patterns, surgical results, and possible operative solutions discussed in the literature for patients with transposition of the great arteries who undergo arterial switch operations that result in late complications. Published journal articles were identified through PubMed literature search. The authors selected 72 articles for analysis. It is concluded that modifications can be made to the arterial switch operation in an effort to meet the challenges presented by late complications.

The changing epidemiology of congenital heart disease

Congenital heart disease is the most common congenital disorder in newborns. Advances in cardiovascular medicine and surgery have enabled most patients to reach adulthood. Unfortunately, prolonged survival has been achieved at a cost, as many patients suffer late complications, of which heart failure and arrhythmias are the most prominent. Accordingly, these patients need frequent follow-up by physicians with specific knowledge in the field of congenital heart disease. However, planning of care for this population is difficult, because the number of patients currently living with congenital heart disease is difficult to measure. Birth prevalence estimates vary widely according to different studies, and survival rates have not been well recorded. Consequently, the prevalence of congenital heart disease is unclear, with estimates exceeding the number of patients currently seen in cardiology clinics. New developments continue to influence the size of the population of patients with congenital heart disease. Prenatal screening has led to increased rates of termination of pregnancy. Improved management of complications has changed the time and mode of death caused by congenital heart disease. Several genetic and environmental factors have been shown to be involved in the etiology of congenital heart disease, although this knowledge has not yet led to the implementation of preventative measures. In this Review, we give an overview of the etiology, birth prevalence, current prevalence, mortality, and complications of congenital heart disease.

Prevalence of early postoperative arrhythmias in children with delayed open-heart surgery for severe congenital heart disease

BACKGROUND; Our aim was to determine the incidence, risk factors and outcome of early postoperative arrhythmias in children with delayed treatment of severe congenital heart disease.

METHODS

A prospective study was conducted in 141 consecutive children with delayed referral from emerging countries, who underwent open-heart surgery.

RESULTS

Sinus node dysfunction was noted in 5 cases. Preoperative moderate extrasystoly was common and its incidence significantly increased in the postoperative phase. Overall, 9 patients required specific antiarrhythmic therapy: 6 for sustained atrioventricular reciprocating tachycardia, and 3 respectively for atrial flutter, atrial fibrillation and junctional ectopic tachycardia. Non-sustained atrioventricular and ventricular tachycardia required no therapy in respectively 6 and 1 case. Postoperative complete atrioventricular block was observed in 6 patients and remained permanent in 3. No major complications resulted from those arrhythmias. Preoperative low oxygen saturation, preoperative arrhythmias, as well as long cardiopulmonary bypass time and aortic cross-clamp time, were risk factors for early postoperative arrhythmias.

CONCLUSIONS

Children with delayed surgery for congenital heart disease are at risk of developing early postoperative arrhythmias depending on the complexity of their disease and of its treatment. However, their prevalence (14%) is not higher than in the general population of cardiac children.

Guidelines for the outpatient management of complex congenital heart disease

An increasingly complex group of children is now being followed as outpatients after surgery for congenital heart disease. A variety of complications and physiologic perturbations, both expected and unexpected, may present during follow-up, and should be anticipated by the practitioner and discussed with the patient and family. The purpose of this position article is to provide a framework for outpatient follow-up of complex congenital heart disease, based on a review of current literature and the experience of the authors.

Cardiac Outcome up to 15 Years After the Arterial Switch Operation

AIMS

To assess the cardiac outcome and risk factors for mortality of infants following the arterial switch operation (ASO).

METHODS

A single-centre retrospective review was conducted. Preoperative assessment, operative management and outcome was detailed for 244 patients undergoing the ASO at Green Lane Hospital for transposition of the great arteries (TGA) or double outlet right ventricle.

RESULTS

The postoperative survival at 1, 5 and 15 years was 85%, 84% and 83%, respectively. The calendar year of ASO and the presence of a ventricular septal defect (VSD) were the primary predictors of early mortality. Late mortality was associated with a side-by-side configuration of the great arteries. Re-intervention following ASO was more common in patients with prolonged cardiopulmonary bypass time.

CONCLUSIONS

Low early and late morbidity and mortality can be obtained in infants with TGA or double outlet right ventricle by definitive repair utilising the ASO.

Factors prolonging length of stay in the cardiac intensive care unit following the arterial switch operation

The arterial switch operation has become the preferred procedure for surgical management of transposition, defined on the basis of concordant atrioventricular and discordant ventriculo-arterial connections. We conducted a retrospective evaluation of our experience in 61 infants with this segmental combination, seen from January, 1997, to July, 2003, in order to determine the factors that are associated with a prolonged postoperative course. Factors independently associated with a prolonged postoperative stay in the cardiac intensive care unit included prematurity, difficulty in feeding, capillary leak, need for preoperative inotropic support, and postoperative infectious complications. Future research is warranted designed to minimize the impact of capillary leak and postoperative infectious complications. In addition, based on these results, our practice has evolved to initiate enteral feedings in the preoperative period if feasible, with such enteral feedings resumed as soon as possible following surgery.

Coronary artery pattern and age impact exercise performance late after the arterial switch operation

OBJECTIVE

The impact of coronary artery pattern on exercise performance after the arterial switch operation is unknown. The purpose of this study was to evaluate the relationship between coronary artery pattern and exercise performance late after the arterial switch operation.

METHODS

Patients who underwent the arterial switch operation and were referred for exercise stress testing between January of 1996 and April of 2005 were included. Univariate and multivariate analyses were performed to identify risk factors for lower maximum heart rate and percent of predicted peak oxygen consumption.

RESULTS

Fifty-three patients were included; 72% were male. The median age at the arterial switch operation was 5 days (1 day to 3.6 years); 32% had concurrent ventricular septal defect repair. The time from the arterial switch operation to exercise stress testing was 14.1 years (7.7-20.6 years). There were 37 patients with the usual coronary artery pattern, and 16 patients (30%) with variant coronary artery patterns. At exercise stress testing, there was no difference in respiratory exchange ratio (1.16 +/- 0.1 for both), indicating similar effort. Compared with patients with the usual coronary artery pattern, patients with variant coronary artery patterns had a significantly lower maximum heart rate (177 +/- 16 beats/min [89% predicted] vs 186 +/- 11 beats/min [93% predicted], respectively, P = .04). Percent of predicted peak oxygen consumption was not significantly different between patients with the usual coronary pattern and patients with variant coronary artery patterns (89% +/- 20% vs 80% +/- 17%, respectively, P = .12). In multivariate analysis, variant coronary artery patterns (P = .03) and ventricular septal defect (P = .004) were predictors of significantly lower maximum heart rate and were associated with a trend toward lower percent of predicted peak oxygen consumption (P < .09). Longer follow-up time was the strongest predictor of lower percent of predicted peak oxygen consumption (P < .001).

CONCLUSIONS

Variant coronary artery patterns are associated with chronotropic impairment, and longer follow-up time is the strongest predictor of diminished aerobic capacity late after arterial switch operation.

Early and mid-term outcome of the arterial switch operation in 114 consecutive patients

BACKGROUND

The arterial switch operation (ASO) has become the treatment of choice in patients with simple or complex transposition of the great arteries (TGA). The purpose of this study was to assess early and mid-term outcome after ASO in a single centre.

PATIENTS AND METHODS

Between 1995 and December 2005, 114 consecutive patients underwent an ASO at our institution, performed by one single surgeon. Patients charts, surgical reports and echocardiograms were retrospectively reviewed. Patients were analyzed in 3 different groups: Group I consisted of 77 neonates with TGA and intact ventricular septum, group II of 13 patients with TGA and ventricular septal defect which had to be closed surgically and group III of 24 patients with various forms of TGA in a complex setting. The patient's median weight was 3.23 kg (1.65-8.30). Twenty-five neonates were born preterm, 18 were diagnosed prenatally. Median follow-up time was 20.7 months (0.3-128.6).

RESULTS

The thirty day mortality was 1.75% (2/114), late mortality 0.88% (1/112) accounting for an overall mortality of 2.63%. There was only one early coronary event and so far no late events. Ten of 111 survivors required reoperation, all but 1 from group III. Prevalence of supravalvular pulmonary stenosis was 4.7%. Freedom from reoperation at 5 years of follow-up time was 87.5%. One patient required permanent pacing, no other late arrhythmias occurred. In our series the only risk factor for increased mortality and morbidity was a body weight of less than 2500 g at the time of operation. No better outcome could be demonstrated in the prenatally diagnosed patients.

CONCLUSION

The ASO can be performed safely and with low mortality and morbidity even in patients with complex TGA. Follow-up of these patients is required to detect residual problems like supravalvular pulmonary stenosis, coronary problems, arrhythmias and aortic valve dysfunction.

Prevalence of arrhythmias and their risk factors mid- and long-term after the arterial switch operation

Early results of the arterial switch operation (ASO) for transposition of the great arteries (TGA) are good, but there are few mid- and long-term data on postoperative arrhythmias, especially in Japan. In this study, clinical data on 624 1-year survivors who had an ASO between 1976 and 1995 were collected from six institutes in Japan up to October 2002. Sixty (9.6%) 1-year survivors had significant arrhythmias. Bradycardia occurred in 22 patients, including complete atrioventricular block (CAVB) in 12, sick sinus syndrome (SSS) in 6, and second-degree atrioventricular block in 4. Syncope developed in 2 with CAVB and 2 with SSS. Ten patients with bradycardia underwent permanent pacemaker implantation. Supraveutricular tachycardia (SVT) was seen in 25 patients, including paroxysmal supraventricular tachycardia in 16, atrial flutter in 7, and atrial fibrillation in 2. Six patients with SVT received antiarrhythmic medication. SVT was transient in 20 and persistent in 5. Ventricular arrhythmias occurred in 13 patients, including nonsustained ventricular tachycardia in 5, paroxysmal ventricular contractions with couplets in 5, ventricular flutter in 2, and sustained ventricular tachycardia in 1. Four patients with ventricular arrhythmias received antiarrhythmic medication. Of the study patients, 8 died 1 year or more after ASO. Death was directly related to arrhythmia in 1 patient and was due to nonsustained ventricular tachycardia with severe congestive heart failure. The presence of a ventricular septal defect (VSD) was a risk factor for postoperative arrhythmia. Patients with TGA and VSD had more arrhythmias than those with TGA and an intact ventricular septum (13.7 vs 8.7%, p < 0.05), and this was especially true for CAVB (3.9% vs 1.0%, p < 0.05). In 36 patients clearly documented time onset of postoperative arrhythmia arrhythmia developed in 18 (50%) after less than 1 year and in 15 (42%) after more than 5 years. In summary serious arrhythmias after ASO were uncommon, but postoperative arrhythmias, such as unpaced CAVB, SSS, and VT, were related to morbidity and mortality. VSD was a risk factor for postoperative arrhythmia, especially CAVB. Approximately half of the arrhythmias developed late. Lifelong monitoring with respect to arrhythmia is needed for patients after ASO.

Superior vena cava stenting and transvenous pacemaker implantation (stent and pace) after the Mustard operation

The Mustard operation for transposition of the great arteries is associated with good long-term survival. Typical complications at follow-up include progressive loss of sinus node function requiring permanent pacemaker implantation, and systemic venous pathway obstruction often precluding a transvenous approach to pacing. We report on 7 patients (median age 14.1; range 5-19) with bradyarrhythmia requiring permanent pacemaker implantation with associated stenosis (n = 6) or occlusion (n = 1) of the superior vena cava, in whom stent implantation relieved the obstruction and facilitated subsequent transvenous permanent pacing. In five of them stenting and pacemaker implantation were performed during a single procedure; two patients underwent elective pacemaker implantation 6 weeks later. In one patient the pacemaker had to be explanted due to pacemaker pocket infection. In the others the follow-up has been uneventful, with excellent chronic pacing thresholds and appropriate sensing. Two patients have had their generator replaced electively.We conclude that stenting of the SVC stenosis allows implantation of transvenous pacemaker leads with good intermediate term results in patients with a Mustard operation for transposition of the great arteries.

Is the arterial switch operation as good over the long term as we thought it would be?

Surgical intervention for hearts with transposition, defined as concordant atrioventricular and discordant ventriculo-arterial connections, has been one of the landmark achievements in the field of paediatric cardiac surgery. In the early 1950s, pioneer surgeons attempted to palliate patients with transposed arterial trunks with an early form of the arterial switch operation. As a result of initially dismal outcomes secondary to difficulties with coronary arterial transfer, the unprepared nature of the morphologically left ventricle, and primitive methods for cardiopulmonary bypass, the arterial switch was abandoned in favour of several procedures achieving correction at atrial and venous levels, culminating in the Mustard and Senning operations.1,2These innovative procedures produced the earliest surviving children with transposition. Although the atrial switch procedures achieved widespread acceptance and success during the mid-1960s through the mid-1980s, the search for an operation to return the great arteries to their normal anatomic positions continued. This pursuit was stimulated primarily by the accumulating observations in mid-to-late term follow up studies of: an increasing frequency of important arrhythmic complications, including sinus nodal dysfunction, atrial arrhythmias, and sudden, unexplained death, by the development of late right ventricular dysfunction and significant tricuspid regurgitation in a ventricle potentially unsuited for a lifetime of systemic function by a small but important prevalence of obstruction of the systemic and/or pulmonary venous pathways, and by dissatisfaction with the operative mortality in the subgroup of infants complicated by additional presence of a large ventricular septal defect.3–6As we have already discussed, a number of novel procedures to achieve anatomic correction had been described as early as 1954, but clinical success was not accomplished until 1975, when Jatene and co-workers7astounded the world of paediatric cardiology with their initial description.

Is Preoperative Delineation of Coronary Artery Pattern a Prerequisite for Arterial Switch Operation?

OBJECTIVE

To determine the effect of preoperative echocardiographic delineation of coronary artery pattern on the immediate postoperative result of arterial switch procedures.

METHODS

A retrospective review of a consecutive series of children who underwent the arterial switch operation at a single institution from February 2001 to December 2004.

RESULTS

Sixty-six children underwent an arterial switch operation. The median age at the time of repair was 1.17 months (range 0.2-96 months). Fifty-five patients (83%) were diagnosed to have dextro-transposition of the great arteries, and 11 patients (17%) had double outlet right ventricle of the Taussig-Bing type. Associated left-sided obstructive lesions were present in 12 cases (18.3%). The dominant coronary pattern was 1 LCX; 2R (60.6%), and followed by 1L; 2RCX (24.2%). The techniques used for coronary transfer were the trapdoor flap, circular buttonhole transfer, or combined technique in all patients except for one case. Preoperatively, the coronary artery anatomy was adequately delineated in only 26 cases (39.4%). Forty patients (60.6%) had either different coronary description or non-documented coronary artery pattern. Myocardial ischemia was not observed in any case postoperatively and no patient in the series required reoperation for coronary revision. There were 10 in-hospital deaths (15%) not related to the coronary pattern. Follow-up is available for 49 of the surviving patients (87.5%) at a mean of 10.1 months. There has been no readmission or reintervention for myocardial ischemia.

CONCLUSIONS

The trapdoor flap and circular buttonhole techniques are the most practical and reproducible maneuvers of coronary transfer during arterial switch operation. Both techniques can compensate for inadequate preoperative echocardiographic delineation of coronary artery pattern.

Efficacy of implantable loop recorders in establishing symptom-rhythm correlation in young patients with syncope and palpitations

OBJECTIVE

To evaluate efficacy of the recently introduced implantable loop recorder (ILR) in establishing symptom-rhythm correlation in young patients with syncope, near syncope, palpitations, and acute life-threatening events (ALTEs).

METHODS

A retrospective study was conducted with patients with ILR from 3 pediatric centers. Inclusion criteria were age <or=25 years and a minimum follow-up of 1 month. All ILR-stored events were analyzed regularly for the presence or absence of an arrhythmia at the time of the symptomatic event.

RESULTS

Twenty-one patients (12 male, 9 female) with an average age of 12.3 +/- 5.3 years (range: 0.8-22 years) were included in the study. Five (24%) patients had structural heart disease, 2 (10%) had a family history of sudden cardiac death, 3 (14%) had QT prolongation on electrocardiogram, and 11 had no cardiovascular disease. Indications for ILR were recurrent syncope and near syncope (n = 15), palpitations (n = 2), and ALTE (n = 2). Fourteen (67%) patients continued to have symptoms, and 7 (33%) had no symptoms after ILR over a follow-up period of 8.4 +/- 4.7 months (range: 1.9-16 months). Symptom-rhythm correlation was possible in all 14 patients who continued to have symptoms (supraventricular tachycardia in 4, ventricular tachycardia in 2, torsades de points in 1, asystole in 1, junctional bradycardia in 1, and sinus rhythm in 5).

CONCLUSIONS

ILR is useful in determining the presence or absence of an arrhythmia during symptoms of syncope, near syncope, and palpitations as well as ALTEs in patients with and without structural heart disease when conventional diagnostic testing, such as electrocardiogram, Holter monitoring, and/or external loop recording, is inconclusive.