Cardiac rhythm disturbances in patients with left atrial isomerism

Reciprocal impulses of junctional origin causing trigeminy

Reciprocal impulses of junctional origin were seen in a patient with left isomerism who had undergone Kawashima repair in infancy. Heterotaxy syndromes are associated with disturbances in sinus node function. Junctional rhythm is hence common in this group. Junctional rhythm can conduct both anterogradely, to the ventricles, and retrogradely, back to the atrium. When it conducts retrogradely, it is termed as atrial echo, which can further conduct back to the ventricle. Our patient had a junctional rhythm with atrial echo beats that conduct to the ventricle, along with an ectopic atrial focus that does not conduct to the ventricle. This is due to variation in the RP interval [between R wave and subsequent P wave] of the echo beat and the atrial ectopic beat with respect to the preceding QRS complex. The timing of the P wave after the QRS complex determines the refractoriness of the atrioventricular node. This exhibits a trigeminal rhythm in our patient.

Perioperative junctional ectopic tachycardia associated with congenital heart disease: risk factors and appropriate interventions

The risk factors and the appropriate interventions for perioperative junctional ectopic tachycardia (JET) in congenital heart disease (CHD) surgery have not been sufficiently investigated despite the severity of this complication. This study aimed to examine the risk factors and interventions for perioperative JET. From 2013 to 2020, 1062 surgeries for CHD (median patient age: 4.3 years, range 0.0-53.0) with or without a cardiopulmonary bypass (CPB) were performed at Hokkaido University, Japan. We investigated the correlation between perioperative JET morbidity factors, such as age, genetic background, CPB/aortic cross-clamp (ACC) time, use of inotropes and dexmedetomidine, STAT score, and laboratory indices. The efficacy of JET therapies was also evaluated. Of the 1062 patients, 86 (8.1%) developed JET. The 30-day mortality was significantly high in JET groups (7% vs. 0.8%). The independent risk factors for JET included heterotaxy syndrome [odds ratio (OR) 4.83; 95% confidence interval (CI) 2.18-10.07], ACC time exceeding 90 min (OR 1.90; CI 1.27-2.39), and the use of 3 or more inotropes (OR 4.11; CI 3.02-5.60). The combination of anti-arrhythmic drugs and a temporary pacemaker was the most effective therapy for intractable JET. Perioperative JET after CHD surgery remains a common cause of mortality. Inotrope use was a risk factor for developing JET overall surgery risk. In short ACC surgeries, heterotaxy syndrome could increase the risk of JET, which could develop even without inotrope use in long ACC surgeries. It is crucial not to delay the treatment in cases with unstable hemodynamics caused by this arrhythmia. It is recommended to reduce numbers not dose of inotropes.

Twin atrioventricular nodes, arrhythmias, and survival in pediatric and adult patients with heterotaxy syndrome

BACKGROUND

Heterotaxy syndrome is likely to involve arrhythmias from associated conduction system abnormalities, which are distinct in different subtypes of isomerism and may change further after interventions and remodeling.

OBJECTIVE

The purpose of this study was to understand the risk of arrhythmias and its relation to isomerism subtypes.

METHODS

Patients diagnosed between 1980 and 2019 as having heterotaxy syndrome were enrolled and grouped as right atrial isomerism (RAI), left atrial isomerism (LAI), or indeterminate isomerism.

RESULTS

Of the 366 patients enrolled, 326 (89.1%) had RAI, 35 (9.6%) LAI, and 5 (1.4%) indeterminate isomerism; 71 (19.4%) patients were adults. Arrhythmias occurred in 37.2% of patients (109 supraventricular tachycardia [SVT], 8 atrial fibrillation/flutter, 12 ventricular tachycardia, and 14 paced bradycardia). Freedom from arrhythmias by the age of 1, 5, 10, 20, and 40 years was 0.849, 0.680, 0.550, 0.413, and 0.053, respectively. Twin atrioventricular nodes were identified in 51.5% of patients with RAI, 8.7% of patients with LAI, and 40.0% of patients with indeterminate isomerism and were the key predictors of SVT. Indeterminate isomerism was also a risk factor for SVT. Other forms of tachycardia appeared relatively late. Sinus bradycardia with junctional rhythm was common in LAI (48.7%) and less in indeterminate isomerism (20.0%), with none occurring in RAI. Only in patients with RAI who showed the poorest survival, ventricular tachycardia worsened the long-term survival.

CONCLUSION

RAI was the predominant subtype of heterotaxy in this cohort. Collectively, the median RAI/LAI ratio was 0.731 and 5.450 in Western and East Asian studies, respectively. Arrhythmias, tachycardia, or paced bradycardia were common, but the spectrum was distinct among subtypes.

Transseptal puncture and catheter ablation via the superior vena cava approach for persistent atrial fibrillation in a patient with polysplenia syndrome and interruption of the inferior vena cava: contact force-guided pulmonary vein isolation

Aims

We sought to establish the technical feasibility of transseptal puncture and left atrial (LA) ablation through the right internal jugular vein via the superior vena cava (SVC) approach in patients with an interrupted inferior vena cava (IVC).

Methods and results

A 34-year-old man with persistent atrial fibrillation (AF) and polysplenia syndrome (hypoplasia of the left kidney, aplasia of the pancreas tail, bilaterally bilobed lungs, and an interrupted IVC) was referred to our hospital for radiofrequency ablation. Because transseptal puncture and LA ablation would be impossible by a standard IVC approach via the femoral vein, we performed transseptal puncture and LA ablation through the right internal jugular vein via the SVC approach using a manually curved Brockenbrough needle and intracardiac echocardiographic guidance. We accomplished pulmonary vein (PV) isolation using a deflectable guiding sheath and a contact force-sensing ablation catheter to monitor the contact force and the force-time integral of the tip of the ablation catheter. No complications occurred during or after the procedure. The patient was discharged home without recurrence of AF 3 days after the procedure. He had no recurrence of AF and was taking no medication 5 months after ablation.

Conclusions

We successfully performed transseptal puncture in a patient with persistent AF, polysplenia syndrome, and complete interruption of the IVC using the superior route through the internal jugular vein. We also accomplished PV isolation using a deflectable guiding sheath and real-time monitoring of the contact force of the ablation catheter.

Lateral Atrial Tunnel Fontan Operation Predisposes to the Junctional Rhythm

The goal of the study was to compare the early postoperative course after fenestrated lateral atrial tunnel (LT) and non-fenestrated extracardiac conduit (EC) Fontan operation (FO) in a single center where both techniques were parallelly used. Between 2004 and 2012, 56(32.7%) children underwent LT and 113(66.1%) EC FO. The mean age was 3.7 ± 2.9 years and mean weight was 14.6 ± 7.3 kg. The most common malformation was hypoplastic left heart syndrome (50.9%). The general approach was to perform LT in children after hemi-Fontan operation and EC in patients after Glenn anastomosis. Medical records were retrospectively reviewed. The hospital survival was 100%. In EC group, cardiopulmonary bypass time (CPB) was shorter (p = 0.004) and less patients needed aortic cross-clamping (p < 0.001). Children after EC stayed longer in the hospital (p = 0.016) and manifested more often prolonged effusions (p = 0.038). The incidence of all forms of junctional rhythm was higher in the LT group, early postoperatively (p < 0.001), during hospitalization (p = 0.004) and at discharge (p < 0.001). Children after LT required more often temporary pacemaker stimulation (p < 0.001). Patients without postoperative normofrequent sinus rhythm had longer CPB time (p = 0.008) and were more often operated on with aortic cross-clamping (p = 0.028). Lateral atrial tunnel Fontan operation with fenestration facilitates early adaptation to the total passive pulmonary flow, but predisposes the patients to the loss of sinus rhythm. The crucial role in the preservation of sinus rhythm plays the last step of the multistage surgery of the single ventricle malformations, probably not only the surgical technique but also factors associated with the cardiopulmonary bypass.

Electrophysiology Study for Complex Supraventricular Tachycardia in Congenital Heart Disease Patients With Single-Ventricle Physiology

BACKGROUND

Supraventricular tachycardia (SVT) is common in complex congenital heart disease (CCHD) patients with single-ventricle physiology and may cause hemodynamic deterioration. We reported the outcomes of catheter ablation for such complex SVT in these single-ventricle CCHD patients.

METHODS AND RESULTS

Patients with single-ventricle physiology (defined as CCHD patients) who received electrophysiology studies and catheter ablation between 1995 and 2015 were studied. We enrolled 30 CCHD patients (18 with right atrial isomerism, 5 with left atrial isomerism, and 7 with other CCHDs; 17 male, 13 female). The age of onset of clinical SVT was 6.7 years (±4.7 years). Electrophysiology studies and ablation were performed at age 7.1 years (±3.9 years); body weight was 20.7 kg (±10.0 kg). Twin atrioventricular nodes were present in 60% of patients (right atrial isomerism, 72.2%; left atrial isomerism, 40%; other CCHDs, 42.9%). Manifested preexcitation was noted in 10% of patients. SVT was induced in 21 patients. Twin atrioventricular nodal reentrant tachycardia was the most common (57.1%), followed by atrioventricular reentrant tachycardia (28.6%), junctional tachycardia (14.3%), and atrioventricular nodal reentrant tachycardia (9.5%). Multiple arrhythmias were common (33.3%), particularly in patients with atrioventricular reentrant tachycardia (50%). Ablation successfully eliminated SVT in 12 of 14 patients (85.7%), with a recurrence rate of 16.7% during 6 years of follow-up.

CONCLUSIONS

Transcatheter ablation of complex SVT substrates, including minor atrioventricular node of twin atrioventricular nodal reentrant tachycardia, accessory pathways of atrioventricular reentrant tachycardia, and a slow pathway of atrioventricular nodal reentrant tachycardia, is effective in CCHD patients. The limitations are limited vascular access and the risk of atrioventricular block.

Arrhythmias in Adult Congenital Patients With Bodily Isomerism

There are an increasing number of adults with congenital heart disease, some of whom have bodily isomerism. Bodily isomerism or heterotaxy is a unique clinical entity associated with congenital malformations of the heart which further increases the risk for future cardiovascular complications. We aimed to investigate the frequency of arrhythmias in adults with bodily isomerism. We utilized the 2012 iteration of the Nationwide Inpatient Sample to identify adult inpatient admissions associated with arrhythmias in patients with isomerism. Data regarding demographics, comorbidities, and various procedures were collected and compared between those with and without isomerism. A total of 6,907,109 admissions were analyzed with a total of 861 being associated isomerism. The frequency of arrhythmias was greater in those with isomerism (20.8 vs. 15.4 %). Those with isomerism were also more five times more likely to undergo invasive electrophysiology studies. Length and cost of hospitalization for patients with arrhythmias also tended to be greater in those with isomerism. Mortality did not differ between the two groups. Arrhythmias are more prevalent in those with isomerism, with a majority of arrhythmias in isomerism being atrial. Those with isomerism and arrhythmias also tended to have greater length and cost of hospitalization.

Fetal Magnetic Resonance Imaging of Malformations Associated with Heterotaxy

Magnetic resonance imaging (MRI) is increasingly used as an investigation during fetal life, particularly for assessment of intracranial masses, congenital diaphragmatic hernia, myelomeningocele, and abdominal masses. As the number of scans increases, so is the variety of congenital malformations being recognized. It is axiomatic that interpretation of the findings is enhanced when attention is paid to the likely findings in the setting of known syndromes, this information then dictating the need for additional acquisition of images. One such syndrome is so-called "visceral heterotaxy", in which there is typically an isomeric, rather than a lateralized, arrangement of the thoracic and abdominal organs. Typically associated with complex congenital cardiac malformations, heterotaxy can also involve the central nervous system, and produce pulmonary, gastrointestinal, immunologic, and genitourinary malformations. In this review, we discuss how these findings can be demonstrated using fetal MRI.

An adult case of polysplenia syndrome associated with sinus node dysfunction, dextrocardia, and systemic venous anomalies

A 54-year-old woman was referred to our hospital for symptomatic sinus bradyarrhythmia with a sinus pause of 8 seconds. She was diagnosed with dextrocardia during childhood and discovered to have heterotaxy syndrome when she had an appendectomy during her teenager years. Chest and abdominal examinations by computed tomography showed multiple spleens located on the right side and abnormal drainages of the superior and inferior vena cava. Left isomerism was diagnosed by bilaterally bilobed lungs. Because of a patent bilateral superior vena cava, pacemaker leads were implanted using the right cephalic vein approach. Her fainting symptoms disappeared after pacemaker implantation.

Permanent epicardial pacing lead implantation for scheduled multistage operations in Fontan candidate

The use of an epicardial pacing lead may be essential in pediatric patients with rhythm disturbances. In patients with single-ventricle physiology who need scheduled multistage operations, the lead could be an obstacle because of the induction of tight adhesions and the need for dissection in the next operation. We propose a novel reproducible technique for the placement of an epicardial pacing lead followed by easy dissection of the entire length of the lead in the next operation in neonates or young infants who need multistage operations.

Magnetic navigation in adults with atrial isomerism (heterotaxy syndrome) and supraventricular arrhythmias

AIMS

We analysed the type and mechanism of supraventricular arrhythmias encountered in a series of symptomatic adults with atrial isomerism undergoing catheter ablation procedures.

METHODS AND RESULTS

The study population included consecutive adults with atrial isomerism who had previously undergone surgical repair or palliation of the associated anomalies. Patients underwent electrophysiological study for symptomatic arrhythmia in our institution between 2010 and 2012 using magnetic navigation in conjunction with CARTO RMT and three-dimensional (3D) image integration. Eight patients (five females) with a median age of 33 years [interquartile range (IQR) 24-39] were studied. Access to the cardiac chambers of interest was obtained retrogradely via the aorta using remotely navigated magnetic catheters in six patients. Radiofrequency ablation successfully targeted twin atrioventricular (AV) nodal reentrant tachycardia in two patients, atrial fibrillation (AF) in three, focal atrial tachycardia (AT) mainly originating in the left-sided atrium in four patients, and macro-reentrant AT dependent on a right-sided inferior isthmus in three patients. The median fluoroscopy time was 3.0 min (IQR 2-11). After a median follow-up of 10 months (IQR 6-21), five of the ablated patients are free from arrhythmia; two patients experienced episodes of self-terminated AF and AT, respectively, within one month post-ablation; the remaining patient had only non-sustained AT during the electrophysiological study and was managed medically.

CONCLUSION

Various supraventricular tachycardia mechanisms are possible in adults with heterotaxy syndrome, all potentially amenable to radiofrequency ablation. The use of remote magnetic navigation along with 3D mapping facilitated the procedures and resulted in a short radiation time.

Outcome of left atrial isomerism at a single institution

Left atrial isomerism includes a complex spectrum of cardiac and extracardiac anomalies. The records of all patients with left isomerism born during the period of 1973-2010 and treated at the Children's Hospital, Helsinki were reviewed. The short- and long-term outcomes were studied. The review included 38 patients (50% females). The overall survival with left atrial isomerism was 63% during a median follow-up time of 16 years (range, 4-30 years). Extracardiac anomalies were noted in 14 (37%) of 38 cases. Cardiac defects included dextrocardia in 26%, partially or totally anomalous pulmonary venous return in 29%, common atrium in 50%, atrioventriculoseptal defect in 73%, single ventricle in 40%, ventriculoseptal defect without atrioventricular defect in 11%, transposition in 21%, double outlet of the right ventricle in 26%, pulmonary stenosis or atresia in 61%, and left ventricular outflow obstruction in 24% of the cases. Cardiac arrhythmias were presented in 71% and pacemaker treatment in 29% of the cases. Of the 38 patients, 33 had cardiac surgery. Simple palliative methods were used in 11 cases, single-ventricle palliation in 12 cases, and operation with a biventricular track in 10 cases. In the groups that had surgery, 3 of 11 patients, 3 of 12 patients, and 3 of 10 patients died, respectively. In this review, 14 deaths occurred, associated with extracardiac anomalies in five cases and with cardiac arrhythmia in four cases. Five postoperative deaths occurred. At this writing, all three patients who had heart transplantation are alive. Complicated heart defects associated with severe arrhythmias and extracardiac anomalies contribute to a high mortality rate with left isomerism. Cardiac transplantation was considered a good option for selected patients.

Perioperative atrial tachycardia is associated with increased mortality in infants undergoing cardiac surgery

OBJECTIVE

Few data are available on the frequency or importance of perioperative atrial tachycardia in infants. We hypothesized that atrial tachycardia in infants undergoing cardiac surgery is not rare and is associated with increased morbidity and mortality.

METHODS

From 2007 through 2010, 777 infants (median age, 1.8 months; interquartile range, 0.33-5.73) underwent cardiac surgery. Their medical records were reviewed for atrial tachycardia during the perioperative period.

RESULTS

Of the 777 patients, 64 (8.2%) developed atrial tachycardia. The independent risk factors for developing atrial tachycardia included surgical age 6 months or younger (odds ratio, 4.4; 95% confidence interval, 1.1-19.15), use of 3 or more inotropes (odds ratio, 2.9; 95% confidence interval, 1.4-6.2), and heterotaxy syndrome (odds ratio, 2.9; 95% confidence interval, 1.1-7.4). All-cause mortality in the atrial tachycardia group was increased (21.9% vs 7.2%, P<.001) during a median follow-up period of 14.6 months (interquartile range, 6.8-24.6), and atrial tachycardia was independently associated with decreased survival (hazard ratio, 1.9; 95% confidence interval, 1.1-3.8). Infants with perioperative atrial tachycardia had a longer hospital length of stay (32 vs 17 days, P<.001) and duration of inotrope use (10.5 vs 3.0 days, P<.001). A total of 57 patients received antiarrhythmic therapy, with propranolol the most common (n=31). Among the survivors, 48 patients received outpatient antiarrhythmic therapy, which was successfully discontinued in 23 patients at a median duration of 14 months (interquartile range, 5.7-18.6) without recurrence.

CONCLUSIONS

Atrial tachycardia is common in infants undergoing cardiac surgery and is independently associated with decreased survival. Among survivors, antiarrhythmic agents successfully controlled atrial tachycardia in most patients with a low recurrence risk after discontinuation.

The incidence and characteristics of supraventricular tachycardia in left atrial isomerism: a high incidence of atrial fibrillation in young patients

BACKGROUND

In left atrial isomerism (LAI), both atria show left atrial morphology. Although bradyarrhythmias are frequent and highly complex in LAI patients, previous studies have reported a low incidence of supraventricular tachycardia (SVT).

METHODS

To evaluate the incidence and characteristics of SVT in LAI, we retrospectively evaluated the clinical characteristics of SVTs in 83 patients with LAI (age at last follow-up, 15.3±10.5 years).

RESULTS

There were 27 SVTs in 19 patients (23%), including nine episodes of atrial fibrillation (AF) and eight non-reentrant SVTs. Sixteen of the 19 patients with SVT had histories of atriotomy, but the three patients with AF or non-reentrant tachycardia had no history of atriotomy. The rates of freedom from SVT were 66% and 59% at ages of 20 and 30 years, respectively; the corresponding rates for freedom from AF were 89% and 74%. In multivariate analysis, the predictors of SVT were age (OR, 1.14; 95% CI, 1.06-1.26; p=0.003) and sinus node dysfunction (SND) (OR, 3.88; 95% CI, 1.57-13.34; p=0.01).

CONCLUSIONS

In patients with LAI, SVTs are common, and AF and non-reentrant SVTs are the major type of SVTs. The incidence of AF was high in young patients with LAI. The lack of anatomical barriers in the atria that allow the formation of macro-reentrant circuits may account for the higher incidence of AF and non-reentrant SVT than macro-reentrant tachycardia. Moreover, the increasing prevalence of SND with age should contribute to a higher incidence of SVT.

A mouse model of conduction system patterning abnormalities in heterotaxy syndrome

Duplication or absence of parts of the specialized cardiac conduction system in patients with heterotaxy syndrome causes significant clinical disease, but the mechanistic basis by which embryonic disruption of left-right patterning alters conduction system patterning in these patients is not well understood. We sought to determine whether a mouse model of X-linked human heterotaxy recapitulates conduction system abnormalities identified in patients with heterotaxy. Cardiac structure and conduction system patterning were evaluated in Zic3 null embryos from e9.5 to e16.5 using genetic and molecular methods. Severe structural abnormalities involving atrial, ventricular, and conotruncal development were associated with a spectrum of disorganized and ambiguous arrangements throughout the conduction system, including the appearance of duplicated structures. The severity and location of conduction system abnormalities correlated with the severity and location of associated structural heart disease and were identifiable at the earliest stages examined. The Zic3 mouse model provides a novel tool to dissect the mechanistic underpinnings of conduction system patterning and dysfunction and its relationship to cardiovascular malformations, making it a promising model to improve understanding and risk assessment in the clinical arena.

Nodoventricular pathway associated with twin AV nodes: complexity of ablation in single ventricle physiology

We report the case of a patient with heterotaxy syndrome including complex single ventricular morphology and interrupted IVC in association with twin conduction systems and a nodoventricular accessory pathway connection. The presence of 3 distinct QRS morphologies was inadvertently discovered during a hemodynamic catheterization study and prompted formal EP testing prior to hepatic venous inclusion into the Fontan circuit and loss of access to the atrial chamber for testing and therapy. This patient underscores the importance of close surveillance and high index of suspicion of arrhythmia mechanisms in patients with heterotaxy syndrome in conjunction with single ventricle morphology.

Intrapartum fetal heart rate monitoring in cases of congenital heart disease

OBJECTIVE

We evaluated the intrapartum fetal heart rate (FHR) patterns in fetuses with congenital heart disease (CHD).

STUDY DESIGN

One hundred sixteen cases of fetal CHD were identified at our institute between 2000-2007; 464 fetuses without CHD were used as controls. The incidences of abnormal FHR patterns and umbilical blood gases were compared.

RESULTS

More fetuses with CHD showed variant FHR than did control fetuses (46.6% vs 17.7%; P < .01). Cesarean section deliveries that were based on fetal indications were performed more frequently in fetuses with CHD than in control fetuses (12.9% vs 3.2%; P < .01). Isomerism and tetralogy of Fallot were observed frequently with variant FHR. When chromosomal abnormalities and intrauterine growth restriction were excluded, the fetuses with CHD showed more variant FHR than did the control fetuses.

CONCLUSION

Fetuses with CHD are more likely to show abnormal FHR patterns than are control fetuses. We suggest that cardiac abnormalities are associated with abnormalities in FHR patterns.

Long-term outcome of twin atrioventricular node and supraventricular tachycardia in patients with right isomerism of the atrial appendage

BACKGROUND

Twin AV nodes and resulting supraventricular tachycardia (SVT) have been described in right atrial isomerism (RAI).

OBJECTIVE

We sought to analyze the long-term outcome of patients with RAI with a focus on rhythm disturbances.

METHODS

Retrospective study of 257 patients (152 male and 105 female, 1,171 patient-years) with RAI diagnosed between 1980 and 2005.

RESULTS

SVT in 68 patients (26%) occurred at various ages from the prenatal period to 15 years and was only significantly associated with balanced ventricles (P = .009). Cardioversion was achieved in by verapamil in 6 of 6 cases (100%), adenosine in 18 of 21 cases (88%) and propranolol in 10 of 12 cases (83%). Electrocardiographic evidence of twin AV nodes, as shown by 2 discrete non-pre-excited QRS complexes, was found in 28 of 44 (64%) patients with more than 2 electrocardiograms, and was more frequent in those with balanced ventricles rather than a dominant ventricle and would increase risk of SVT. Recurrence of SVT was documented in 27 (40%) patients 1 day to 4.5 years after the first episode. However, the occurrence or recurrence of SVT was not associated with increased all-cause or surgical mortality or sudden death. Successful catheter ablation of ventriculoatrial pathways with junctional ectopic tachycardia at radiofrequency energy delivery was obtained in 5 of 6 patients.

CONCLUSION

This study showed that twin AV nodes in RAI patients could be disclosed by serial electrocardiograms and that SVT, most likely a twin node tachycardia, was common and tended to recur but could be managed by ablation or medication.

Controversies, genetics, diagnostic assessment, and outcomes relating to the heterotaxy syndrome

How best to analyse and describe the features of the situation commonly known as "visceral heterotaxy" remains controversial. Much of the disagreement devolves on how to deal with the concept of isomerism. In the opinion of some, the concept of bilateral right-sidedness and bilateral left-sidedness, while useful in helping to remember which abnormalities are likely to occur in asplenia or polysplenia, should not be granted the status of a specific "situs", since there are numerous examples of exceptions to these patterns. On the other hand, those who favour the concept of isomerism point out that, when describing only the heart, and taking the structure of the atrial appendages as the starting point for analysis, basing this on the extent of the pectinate muscles relative to the atrioventricular junctions, then the only possible arrangements for the appendages are the usual one, its mirror-image, and the two situations in which appendages of comparable morphology are found on both sides of the heart, these being the arrangements of right or left isomerism. It is certainly the case that the arrangement of the organs is not always in harmony with the arrangement of the atrial appendages, but those circumstances, in which there is disharmony, can readily be described by paying specific attention to each series of organs. On this basis, in this review, we describe the approach to heterotaxy, and isomerism of the atrial appendages, in terms of the genetic background, the diagnosis, and outcomes after cardiac surgery. Attention is given to the various diagnostic modalities, including fetal and postnatal echocardiography, recent tomographic and magnetic resonance imaging techniques, and the time-honoured approach using angiography.

Heart rate dynamics during and after exercise in postoperative congenital heart disease patients. Their relation to cardiac autonomic nervous activity and intrinsic sinus node dysfunction

BACKGROUND

Abnormal exercise-related heart rate (HR) dynamics, that is, blunted exercise HR response, lower peak HR, and delayed HR recovery after exercise, are associated with high morbidity and mortality in adults with acquired and congenital heart disease (CHD). However, the precise mechanisms underlying the abnormal HR dynamics remain unclear.

OBJECTIVES

The purpose of this study is to evaluate the precise contribution of cardiac autonomic nervous activity (CANA) and sinus node function on exercise-related HR dynamics in postoperative patients with CHD.

METHODS

We analyzed our previous data in 53 postoperative patients with CHD who had undergone pharmacologic evaluation, including intrinsic HR, and compared the results with HR dynamics.

RESULTS

Intrinsic HR (84% +/- 11%) was lower than the expected value and independently correlated with resting HR (P < .05). Univariate analysis demonstrated that all CANA indices significantly correlated with most HR dynamic parameters. On multivariate analysis, basal parasympathetic nervous activity significantly influenced all HR dynamics (P < .05-.0001), except for peak HR, whereas postsynaptic beta sensitivity of the sinus node significantly influenced all HR dynamics (P < .05-.001), except for early HR recovery. Resting plasma norepinephrine significantly correlated with all HR dynamics (P < .05-.001), except for resting HR.

CONCLUSIONS

Lower resting and peak HRs are independently associated with intrinsic sinus node dysfunction and abnormal sympathetic CANA, respectively. A blunted HR increase and delayed early HR recovery are independently associated with impaired sympathetic and parasympathetic CANAs with the greater influence on a blunted exercise HR increase.

Cardiac perforation 6 weeks after percutaneous atrial septal defect repair using an Amplatzer septal occluder

A 14-year-old boy presented to the emergency department unaccompanied by his parents with a decreased level of consciousness, bradycardia, and hypotension after a syncopal episode. The patient's electronic chart revealed a percutaneous closure of a secundum atrial septal defect using an Amplatzer septal occluder (AGA Medical, Golden Valley, MN) 6 weeks before this presentation. An urgent echocardiogram revealed a moderate pericardial effusion, and 320 mL of fresh blood was evacuated by subxiphoid pericardiocentesis. The child underwent surgical exploration and was found to have a perforation in the superior-posterior aspect of the right atrium, which was corrected. The septal occluder was extracted, and the atrial septal defect was closed with a pericardial patch. This case illustrates a rare but life-threatening complication of percutaneous closure of atrial septal defect using an Amplatzer septal occluder and the importance of timely access to patient records when available history and physical examination are limited.

Late Assessment After Biventricular Repair for Isomerism Heart

BACKGROUND

Although biventricular repair is theoretically ideal for the treatment of isomerism heart, the long-term outcome is unknown. We assessed the outcome of biventricular repair for atrial isomerism.

METHODS

From 1984 to 2002 in our surgical database, 10 of 67 patients with atrial isomerism received biventricular repair. The age at operation was 7.7 +/- 9.1 years. Preoperative ventricular volume was normal in all patients. Left ventricular ejection fraction was 62% +/- 8%. Intra-atrial rerouting was required in 8. The atrioventricular septal defect with double-outlet right ventricle was closed using comma-shaped intraventricular conduit in 8. Other procedures included pulmonary valvotomy and infundibulectomy in 2, transannular patch in 1 and right ventricle to pulmonary artery conduit in 1.

RESULTS

There was one early death due to hemolytic phagocytic syndrome. The other 9 patients are in New York Heart Association class I at 12.7 +/- 5.3 years postoperatively. There was no atrial baffle stenosis except in 1 patient; it was successfully treated by stent placement 10 years after the operation. There was no incidence of left ventricular outflow obstruction. Mitral replacement (4 months postoperatively) or repair (15 years postoperatively) was done in 2 patients. The other 5 patients with atrioventricular septal defect showed trivial to mild regurgitation in the long-term period. Arrhythmia was observed in 5 (left 4, right 1). Catheter ablation was needed in a patient with atrial flutter. Three of 9 patients require diuretics or digitalization, or both.

CONCLUSIONS

The long-term outcome of the biventricular repair for atrial isomerism was excellent. Late development of mitral regurgitation and arrhythmia could be managed adequately.

Late Occurrence of Adenosine-Sensitive Focal Junctional Tachycardia in Complex Congenital Heart Disease

BACKGROUND

Although supraventricular tachycardia in complex congenital heart disease (CHD) has been reported after surgical repair, its exact electrophysiologic identification has been limited to intraatrial reentrant tachycardia (IART). Moreover, junctional tachycardia (JT) has not previously been described as a cause of late postoperative arrhythmia.

METHODS AND RESULTS

Since 1993, a total of 12 patients with congenital heart disease presented with paroxysmal focal JT. The patients with only typical immediate postoperative junctional ectopic tachycardia were excluded. Medical records, standard electrocardiography and Holter monitoring were reviewed. An intracardiac electrophysiologic (EP) study was performed in 11 patients. Ten patients were in post-Fontan status (5.7% of total Fontan survivors). Focal JT occurred more frequently in heterotaxy syndrome among the Fontan survivors (7/52 vs. 3/124; P < 0.05). The commonest anatomy of the atrioventricular (AV) junction was complete AV canal in 8 patients. EP characteristics of focal JT were as follows: (1) various tachycardia mechanisms were identified (increased automaticity or a triggered mechanism in 6/11, and focal reentry in 5/11, including one concealed nodofascicular pathway) (2) ventriculoatrial conduction during tachycardia was either dissociation (7/12) or variable (5/12) (3) All JTs were terminated by adenosine. Class III antiarrhythmic agent was effective in 5/6. His bundle ablation was performed in one Fontan patient, who already had pacemaker because of accompanying intractable IART and sinus node dysfunction.

CONCLUSION

Focal JT may be a source of late term supraventricular tachycardia in patients with complex CHD. The tachycardia mechanism was either automatic/triggered or reentrant. In all patients, JT was effectively terminated by adenosine.

Twin AV Node and Induced Supraventricular Tachycardia in Fontan Palliation Patients

INTRODUCTION

The coexistence of two distinct atrioventricular (AV) nodes has been described in congenital heart disease requiring Fontan type palliation. The purpose of this study was to evaluate the occurrence of twin AV node according to anatomical subgroups, and to determine its relation to tachycardia.

METHODS

From 2001 to 2003, we performed an electrophysiologic (EP) study upon 52 consecutive patients who had undergone cardiac catheterization after Fontan completion. Atrial pacing was performed at three or more different atrial sites.

RESULTS

In 10/52 patients, two different QRS complexes were recorded at different pacing sites, suggesting twin AV node (9/20 in right isomerism, 1/8 discordance AV connections, 0/24 other complex anomalies). AV reciprocating tachycardia (AVRT), presumably involving two AV nodes and a connecting sling, was induced in 6 of 10 patients who had twin AV node (4/6 used posterior AV node as an antegrade limb, 2/6 used an anterior AV node as an antegrade limb). Heterotaxy syndrome (P < 0.001) and complete AV septal defect (P = 0.002) were found to be risk factors for twin AV node. Junctional tachycardia (JT; HR > 150/min) with either VA dissociation (7/9) or second degree VA block (2/9) were induced by pacing or isoproterenol infusion in 9/52 patients.

CONCLUSION

JT induction was associated with a twin AV node (P = 0.04), or a history of early postoperative junctional ectopic tachycardia (P = 0.02). A complicated AV node conduction system such as twin AV node was frequent in heterotaxy syndrome. Both AVRT and JT with VA block may be important causes of tachyarrhythmia in this patient group.

Assessment of intracardiac anomalies in two adults with Ivemark's syndrome

Ivemark's syndrome consists of intracardiac anomalies, abnormal lobation of the lungs, and abdominal heterotaxy. A frequent intracardiac anomaly seen in Ivemark's syndrome is a common atrium, which is associated with left-to-right shunting. The increased blood flow and resistance within the pulmonary vasculature creates pulmonary hypertension and eventual reversal of the shunt physiology. In the absence of additional cyanotic malformations, survival into adulthood without prior surgical septation of the common atrium depends on the extent of pulmonary hypertension and intracardiac right-to-left shunting. We present two patients with a common atrium in the setting of Ivemark's syndrome who survived into adulthood without prior operation. Two-dimensional echocardiography assessed their intracardiac structures. One patient had right atrial isomerism manifested by asplenia and a common atrium, into which the hepatic veins drained directly, and the other patient had left atrial isomerism manifested by polysplenia, a common atrium, and a ventricular septal defect with a single atrioventricular valve. Neither patient had additional cyanotic malformations, including obstruction to pulmonary venous return, transposition of the great vessels, or pulmonic valve stenosis. The 2-dimensional echocardiogram guides the clinician to refer patients for surgical septation of the common atrium before the right-to-left shunt physiology predominates. The medical and surgical treatment of these patients is discussed.

Sinus node dysfunction after Fontan modifications--influence of surgical method

BACKGROUND

Sinus node dysfunction (SND) is reported to be a troublesome complication following various types of Fontan operations. The correlation of post-Fontan SND with surgical methods was evaluated in this study.

METHODS

By reviewing the medical records, surface ECGs, and Holter monitoring, the range of heart rate (HR) and the risk of SND at intermediate term after Fontan type operation (follow up: 41.3+/-13.1 months) were analyzed between two age matched groups of patients, consisting of the extracardiac conduit group (EC, n=33) and the lateral tunneling group (LT, n=35).

RESULTS

Junctional rhythm was observed in nine out of 35 patients in LT and five out of 33 patients in EC during the follow-up period. Resting HR was faster in EC than that in LT (108+/-15 vs. 82+/-21, P<0.001). Average and maximal HR in Holter monitoring were also faster in EC than those in LT. SND was found in 13 cases (10 in LT, three in EC) during follow-up and one required pacemaker implantation. In the case of situs solitus heart, SND was less frequent in EC than in LT (0/16 vs. 8/26, P=0.01). In the case of heterotaxy syndrome, SND occurred in similar number of cases (3/17 vs. 2/9). The staged approach to Fontan completion did not influence SND. LT repair was the only factor causing sinus node dysfunction according to multivariate logistic regression (P=0.03, OR 5.96).

CONCLUSIONS

Lateral tunnel type surgical repair was more likely to lead to the development of sinus node dysfunction than extracardiac conduit operation. In the case of heterotaxy syndrome, surgical method had no significant influence.