Postoperative Junctional Ectopic Tachycardia: Risk Factors for Occurrence in the Modern Surgical Era

Epidemiology of Postoperative Junctional Ectopic Tachycardia in Infants Undergoing Cardiac Surgery

BACKGROUND

Junctional ectopic tachycardia (JET) complicates congenital heart surgery in 2% to 8.3% of cases. JET is associated with postoperative morbidity in single-center studies. We used the Pediatric Cardiac Critical Care Consortium data registry to provide a multicenter epidemiologic description of treated JET.

METHODS

This is a retrospective study (February 2019-August 2022) of patients with treated JET. Inclusion criteria were (1) <12 months old at the index operation, and (2) treated for JET <72 hours after surgery. Diagnosis was defined by receiving treatment (pacing, cooling, and medications). A multilevel logistic regression analysis with hospital random effect identified JET risk factors. Impact of JET on outcomes was estimated by margins/attributable risk analysis using previous risk-adjustment models.

RESULTS

Among 24,073 patients from 63 centers, 1436 (6.0%) were treated for JET with significant center variability (0% to 17.9%). Median time to onset was 3.4 hours, with 34% present on admission. Median duration was 2 days (interquartile range, 1-4 days). Tetralogy of Fallot, atrioventricular canal, and ventricular septal defect repair represented >50% of JET. Patient characteristics independently associated with JET included neonatal age, Asian race, cardiopulmonary bypass time, open sternum, and early postoperative inotropic agents. JET was associated with increased risk-adjusted durations of mechanical ventilation (incidence rate ratio, 1.6; 95% CI, 1.5-1.7) and intensive care unit length of stay (incidence rate ratio, 1.3; 95% CI, 1.2-1.3), but not mortality.

CONCLUSIONS

JET is treated in 6% of patients with substantial center variability. JET contributes to increased use of postoperative resources. High center variability warrants further study to identify potential modifiable factors that could serve as targets for improvement efforts to ameliorate deleterious outcomes.

Junctional Ectopic Tachycardia Caused by Junctophilin-2 Expression Silencing Is Selectively Sensitive to Ryanodine Receptor Blockade

Junctional ectopic tachycardia (JET) is a potentially fatal cardiac arrhythmia. Hcn4:shJph2 mice serve as a model of nodal arrhythmias driven by ryanodine type 2 receptor (RyR2)-mediated Ca2+ leak. EL20 is a small molecule that blocks RyR2 Ca2+ leak. In a novel in vivo model of JET, Hcn4:shJph2 mice demonstrated rapid conversion of JET to sinus rhythm with infusion of EL20. Primary atrioventricular nodal cells demonstrated increased Ca2+ transient oscillation frequency and increased RyR2-mediated stored Ca2+ leak which was normalized by EL20. EL20 was found to be rapidly degraded in mouse and human plasma, making it a potential novel therapy for JET.

Clinical risk prediction score for post-operative accelerated junctional rhythm and junctional ectopic tachycardia in children with congenital heart disease

BACKGROUND

Accelerated junctional rhythm (AJR) and Junctional ectopic tachycardia (JET) are common post-operative arrhythmias associated with morbidity/mortality. Studies suggest that pre- or intra-operative treatment may improve outcomes, but patient selection remains a challenge.

OBJECTIVES

Our objective was to describe contemporary outcomes of post-operative AJR/JET and develop a risk-prediction score to identify patients at highest risk.

METHODS

Retrospective cohort study of children 0-18 years undergoing cardiac surgery (2011-2018). AJR was defined as usual complex tachycardia with ≥1:1 ventricular-atrial association and junctional rate >25^th percentile of sinus rate for age but < 170 bpm while JET was defined as a rate >170 bpm. A risk prediction score was developed using random forest analysis and logistic regression.

RESULTS

From 6364 surgeries, AJR occurred in 215 (3.4%) and JET in 59 (0.9%). Age, heterotaxy syndrome, aortic cross-clamp time, ventricular septal defect closure and atrio-ventricular canal repair were independent predictors of AJR/JET on multivariate analysis and included in the risk prediction score. The model accurately predicted the risk of AJR/JET with a C-index of 0.72 [95% CI 0.70, 0.75]. Post-operative AJR and JET was associated with prolonged ICU and hospital length of stay, but not with early mortality.

CONCLUSION

We describe a novel risk prediction score to estimate the risk of post-operative AJR/JET permitting early identification of at-risk patients who may benefit from prophylactic treatment.

β1-receptor polymorphisms and junctional ectopic tachycardia in children after cardiac surgery

Junctional ectopic tachycardia (JET) is a potentially life-threatening postoperative arrhythmia in children with specific congenital heart defects and can contribute significantly to postoperative morbidity for at-risk populations. In adults, β1-adrenergic receptor (ADRB1) and β2-adrenergic receptor (ADRB2) genotypes have been associated with increased risk for arrhythmias. However, their association with arrhythmia risk in children is unknown. We aimed to test associations between ADRB1 and ADRB2 genotypes and postoperative JET in patients with congenital heart defects. Children who underwent cardiac surgery were genotyped for the ADRB1 p.Ser49Gly (rs1801252; c.145A>G), p.Arg389Gly (rs1801253; c.1165C>G), ADRB2 p.Arg16Gly (rs1042713; c.46A>G), and p.Glu27Gln (rs1042714; c.79G>C) polymorphisms. The occurrence of postoperative JET was assessed via cardiologist-interpreted electrocardiograms. Genotype associations with JET were analyzed via logistic regression, adjusted for clinical variables associated with JET, with separate analysis in patients not on a β-blocker. Of the 343 children included (median age 8 months, 53% boys, 69% European ancestry), 45 (13%) developed JET. The Arg389Arg genotype was not significantly associated with JET in the overall population (odds ratio [OR] = 1.96, 95% confidence interval [CI] = 0.96-4.03, p = 0.064), but was nominally associated in patients not taking a β-blocker (n = 324, OR = 2.25, 95% CI = 1.05-4.80. p = 0.034). None of the other variants were associated with JET. These data suggest that the ADRB1 Arg389Arg genotype may predict risk for JET following cardiac surgery in pediatric patients in the absence of β-blockade. Whether treatment with a β-blocker ameliorates this association requires further research.

Sotalol versus amiodarone for postoperative junctional tachycardia after congenital heart surgery

BACKGROUND

Junctional ectopic tachycardia (JET) is a common arrhythmia after congenital heart disease surgery. There is variability in the choice of antiarrhythmic therapy, with amiodarone used commonly. Intravenous (IV) sotalol is a newly available agent that may be useful for JET.

OBJECTIVE

The purpose of this study was to evaluate the safety and efficacy of IV sotalol for postoperative JET and compare outcomes with IV amiodarone.

METHODS

This is a retrospective single-center study of all patients who received IV sotalol or IV amiodarone for postoperative JET at Texas Children's Hospital from December 15, 2015, to December 15, 2020. Data included antiarrhythmic efficacy, hemodynamics, and adverse effects. Successful JET control was defined as a decrease in JET rate to <170 beats/min (or decrease by >20%), or conversion to sinus rhythm, with persistent control over 24 hours without requiring alternative antiarrhythmics or mechanical support.

RESULTS

A total of 32 patients (median age 71 days; interquartile range 17-221 days) received IV amiodarone (n = 20 [62%]) or IV sotalol (n = 12 [38%]) for postoperative JET. Amiodarone was successful in treating JET in 75% of cases; sotalol was successful in 83%. The JET rate decreased faster over the first 90 minutes after a sotalol bolus (25 beats/min per hour) than after an amiodarone bolus (8 beats/min per hour) (P < .01); no heart rate difference was seen after 24 hours. Amiodarone infusion was discontinued early because of hypotension/bradycardia in 2 patients; this was not required in any patients receiving sotalol.

CONCLUSION

For children with postoperative JET, both IV sotalol and amiodarone are safe and efficacious. IV sotalol may lead to a faster improvement in heart rate.

Ivabradine Versus Amiodarone in the Management of Postoperative Junctional Ectopic Tachycardia: A Randomized, Open-Label, Noninferiority Study

OBJECTIVES

This study sought to compare the efficacy of ivabradine and amiodarone in the management of postoperative junctional ectopic tachycardia (JET) after cardiac surgery in children.

BACKGROUND

JET is a serious arrhythmia occurring in children after cardiac surgery and requires aggressive management. Amiodarone has been conventionally used in its treatment. Recent studies have reported the utility of ivabradine in this regard.

METHODS

In this open-label randomized controlled trial, 94 children (age ≤18 years) who developed postoperative JET were allocated to receive either amiodarone or ivabradine. The primary endpoint was restoration of normal sinus rhythm.

RESULTS

Sinus rhythm was achieved in 43 out of the 46 patients (93.5%) in the amiodarone group and 46 out of the 48 patients (95.8%) in the ivabradine group (mean difference of treatment effect: 2.3%; 95% confidence interval: -6.7% to 11.5%). The median (interquartile range) time taken to achieve sinus rhythm conversion was similar in both the groups: 21.5 (17-30.2) hours versus 22 (13.4-38.5) hours (p = 0.36)]. The time taken to rate control of JET was significantly less in the amiodarone group: median 7.0 (5.5-9.5) hours versus 8.0 (5.8-10.8) hours (p = 0.02)]. No drug-related adverse events were observed in the ivabradine group.

CONCLUSIONS

Oral ivabradine is not inferior to intravenous amiodarone in converting postoperative JET to sinus rhythm. There was no difference in time taken to sinus rhythm conversion between the groups, although the rate control was earlier in patients who received amiodarone. Monotherapy with ivabradine may be considered as an alternative to amiodarone in the management of postoperative JET. (Comparison of Two Drugs, Ivabradine and Amiodarone, in the Management of Junctional Ectopic Tachycardia, an Abnormality in Cardiac Rhythm in Patients Under 18 years Who Undergo Cardiac Surgery: CTRI/2018/08/015182).

Early postoperative arrhythmias in patients undergoing congenital heart surgery

Background

This study aims to evaluate early postoperative arrhythmias in children undergoing congenital cardiac surgery.

Methods

A total of 670 pediatric patients (355 males, 315 females; median age: 4 months; range, 1 day to 18 years) who underwent cardiac surgery due to congenital heart defects between December 2018 and November 2019 were included. The rate of postoperative arrhythmias, diagnosis, potential risk factors, and management strategies were evaluated. Multivariate regression analysis was used to identify significant factors of development of postoperative arrhythmias.

Results

Tachyarrhythmia was detected in 54 patients (8.1%), and the most common tachyarrhythmia was junctional ectopic tachycardia. Medical treatment was required in 25/38 (66%) of junctional ectopic tachycardia patients. Amiodarone was initiated in 18, dexmedetomidine in five, and flecainide + amiodarone in two of the patients. Different degrees of atrioventricular block were observed in 30 patients (4.5%). In 12 patients, permanent pacemakers were implanted during hospitalization. Age at the time of surgery under one-year-old, high inotropic scores, prolonged operation time, and high Aristotele"s scores were independent risk factors associated with early postoperative arrhythmia (p<0.05). The most common operations associated with early postoperative arrhythmia were left ventricular outflow tract, (6/20, 30%), complete atrioventricular septal defect (13/53, 24%), and tetralogy of Fallot (20/134, 14%) surgeries.

Conclusion

Cardiac arrhythmias are common in the early period after congenital heart surgery in children. The diagnosis and frequency of arrhythmias may vary according to different surgical procedures.

Junctional Ectopic Tachycardia: Recognition and Modern Management Strategies

Junctional ectopic tachycardia is a common dysrhythmia after congenital heart surgery that is associated with increased perioperative morbidity and mortality. Risk factors for development of junctional ectopic tachycardia include young age (neonatal and infant age groups); hypomagnesemia; higher-complexity surgical procedure, especially near the atrioventricular node or His bundle; and use of exogenous catecholamines such as dopamine and epinephrine. Critical care nurses play a vital role in early recognition of dysrhythmias after congenital heart surgery, assessment of hemodynamics affecting cardiac output, and monitoring the effects of antiarrhythmic therapy. This article reviews the underlying mechanisms of junctional ectopic tachycardia, incidence and risk factors, and treatment options. Currently, amiodarone is the pharmacological treatment of choice, with dexmedetomidine increasingly used because of its anti-arrhythmic properties and sedative effect.

Junctional ectopic tachycardia (JET)

Junctional ectopic tachycardia (JET) is a tachyarrhythmia arising from the atrioventricular node and His bundle area. Enhanced normal automaticity has been postulated as the mechanism of JET in the majority of patients. It is more common in children and can be seen as congenital or in postoperative settings. It is often a narrow complex tachycardia but can present as a wide complex tachycardia as a result of aberrant conduction. Its differentiation from other arrhythmias especially atrioventricular nodal reentrant tachycardia (AVNRT) can be challenging. Medical treatment of JET is difficult, and catheter ablation remains the mainstay of treatment in refractory cases with a high risk of atrioventricular block and recurrence.

Junctional ectopic tachycardia in infants and children

Tachyarrhythmias originating in the atrioventricular (AV) node and AV junction including the bundle of His complex (BH) are called junctional tachycardia (JT) or junctional ectopic tachycardia (JET). Congenital JET (CJET) is a rare arrhythmia that occurs in patients without a preceding cardiac surgery and can be refractory to medical therapy and associated with high morbidity and mortality. CJET has a high rate of morbidity and mortality with death occurring in 35% of cases. JET occurring within 72 hours after cardiac surgery is referred to as postoperative JET (POJET) and caused by direct trauma, ischemic, or stretch injury to the AV conduction tissues during surgical repair of congenital heart defects. Focal junctional tachycardia (FJT) is also known as automatic junctional tachycardia and includes paroxysmal or non-paroxysmal forms. We discuss a staged approach to therapy with improved pharmacological therapies and the use of catheter-based therapies.

Predictors of Early Postoperative Supraventricular Tachyarrhythmias in Children After the Fontan Procedure

Postoperative arrhythmias are a frequent and fatal complication after the Fontan operation. However, clinical evidence demonstrating early postoperative arrhythmias in children undergoing the Fontan operation is limited. This study aimed to evaluate the prevalence of arrhythmias and identify the predictors of early postoperative supraventricular tachyarrhythmias (SVTs) after the Fontan procedure.Data were analyzed from 80 pediatric patients who underwent Fontan procedures between April 2000 and December 2017 in a single-center retrospective study. Early postoperative SVTs were defined as arrhythmias within 30 days after the Fontan procedure. We divided the patients into two groups, with or without early postoperative arrhythmias, and the predictors of early postoperative arrhythmias were analyzed. A multivariate logistic regression analysis was performed to determine independent predictors of early postoperative SVTs after the Fontan procedure.Early postoperative SVTs were observed in 21 patients (26.3%). The most common arrhythmia was junctional ectopic tachycardia. After an adjustment, an atrioventricular valve regurgitation (AVVR) grade of ≥2 (odds ratio 10.54, 95% confidence interval 2.52 to 44.17, P = 0.001) and preoperative arrhythmias (odds ratio 26.49, 95% confidence interval 1.64 to 428.62, P = 0.021) were significant predictors of early postoperative SVTs after the Fontan operation.An AVVR grade ≥2 and preoperative arrhythmia were significant predictors associated with early postoperative SVTs. Intervention for AVVR may provide clinical benefit for preventing early postoperative arrhythmias after the Fontan operation.

Efficacy of prophylactic dexmedetomidine in preventing postoperative junctional ectopic tachycardia in pediatric cardiac surgery patients: A systematic review and meta-analysis

BACKGROUND

Junctional ectopic tachycardia is a serious tachyarrhythmic complication following pediatric cardiac surgery. It is difficult to manage and is associated with significant morbidity and mortality. Conventional nonpharmacological and pharmacological measures have shown limited effects. Dexmedetomidine is an α2 agonist which has recently been shown in multiple studies to be effective.

AIMS

The aim of this systematic review with meta-analysis was to evaluate the efficacy of prophylactic dexmedetomidine administration in the prevention of junctional ectopic tachycardia in pediatric patients following cardiac surgeries.

METHODS

We searched MEDLINE, EMBASE, Cochrane, Web of Science, and relevant references published in English before December 20, 2017 and performed meta-analysis on the selected studies, with one group receiving prophylactic perioperative dexmedetomidine administration and another group receiving placebo. The primary outcome was the incidence of junctional ectopic tachycardia, secondary outcomes included bradycardia, hypotension, intensive care unit stay, total hospital stay, inotropic scores, and total mechanical ventilation time. Odds ratio or mean difference with 95% confidence intervals were calculated using a random effect model.

RESULTS

Seven studies (5 prospective randomized studies and 2 retrospective case-controlled studies) with a total of 1616 patients were analyzed. The incidence of junctional ectopic tachycardia in the dexmedetomidine group was significantly reduced compared to placebo. Similarly, intensive care unit stay, inotropic scores, and total mechanical ventilation time were also significantly decreased in the dexmedetomidine group. No significant increases in adverse events were found. Mortality was low in both groups.

CONCLUSION

Prophylactic dexmedetomidine is effective in reducing the incidence of postoperative junctional ectopic tachycardia without significant increases in adverse events in pediatric patients undergoing surgery for congenital heart diseases.

Standardized training for AVT pacing in paediatric patients with postoperative junctional ectopic tachycardia

BACKGROUND

Junctional ectopic tachycardia is a serious complication of surgery for paediatric congenital heart disease. R-wave synchronized atrial (AVT) pacing, an innovative temporary pacing technique, restores atrioventricular synchrony in these patients. The method is highly effective but technically complex. A standardized training model exists for doctors but not for paediatric intensive care nurses.

AIMS

This study seeks to evaluate whether a standardized programme involving simulation and vignettes increases knowledge of AVT pacing and accuracy of its documentation, as well as recognition and management of specific complications.

STUDY DESIGN

This study was an experimental simulation test with before and after descriptive evaluation.

METHODS

A custom-made simulation model was used in combination with standardized training. Before and after training, 10 paediatric nurse specialists were asked to document pacing, to identify complications and to intervene as necessary. Four clinical scenarios were presented: effective AVT pacing, ineffective AVT pacing, pacing with narrow interval between atrial pacing and ventricular sensing and pacemaker-induced tachycardia. Identification and management of complications were evaluated using a 3-point scale.

RESULTS

Training improved the quality of documentation and complication management. At outset, documentation by 1 of 10 participants was completely correct, and after training, documentation by 8 of 10 participants was completely correct. Before training, 30% of interpretations of the four presented clinical scenarios were correct (12/40) versus 83% (33/40) after training. The decision to notify a doctor of a complication was correct in 83% (33/40) before versus 95% (38/40) after the training.

CONCLUSION

Standardized simulation training improves quality and safety in AVT pacing, with more accurate documentation of the pacing mode and better recognition and management of specific complications during pacing.

RELEVANCE TO CLINICAL PRACTICE

AVT pacing should be performed in conjunction with standardized simulation training in paediatric cardiac intensive care units.

Does dexmedetomidine have an antiarrhythmic effect on cardiac patients? A meta-analysis of randomized controlled trials

Background

Cardiac surgery patients often experience several types of tachyarrhythmias after admission to the intensive care unit (ICU), which increases mortality and morbidity. Dexmedetomidine (DEX) is a popular medicine used for sedation in the ICU, and its other pharmacological characteristics are gradually being uncovered.

Purpose

To determine whether DEX has an antiarrhythmic effect after cardiac surgery.

Methods

The three primary databases MEDLINE, Embase (OVID SP) and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched, and all English-language and randomized control-designed clinical publications comparing DEX to control medicines for sedation after elective cardiac surgery were included. Two colleagues independently extracted the data and performed other quality assessments. A subgroup analysis was performed according to the different medicines used and whether cardiopulmonary bypass (CPB) was applied. All tachyarrhythmias that occurred in the atria and ventricles were analyzed.

Results

A total of 1295 patients in 9 studies met the selection criteria among 2587 studies that were screened. After quantitative synthesis, our results revealed that the DEX group was associated with a lower incidence of ventricular arrhythmia (VA, OR 0.24, 95% CI 0.09–0.64, I² = 0%, P = 0.005) than the control group. Subgroup analysis did not reveal a significant difference between the DEX and propofol subgroups (OR 0.13, 95% CI 0.03–0.56, I² = 0%, P = 0.007). Additionally, no difference in the incidence of atrial fibrillation (AF) was observed regardless of the different control medicines (OR 0.82, 95% CI 0.60–1.10, I² = 25%, P = 0.19) or whether CPB was applied.

Conclusions

This meta-analysis revealed that DEX has an antiarrhythmic effect that decreases the incidence of VA compared to other drugs used for sedation following cardiac surgery. DEX may not have an effect on AF, but cautious interpretation should be exercised due to high heterogeneity.

Risk Factors for Development of Ectopic Atrial Tachycardia in Post-operative Congenital Heart Disease

Ectopic atrial tachycardia (EAT) is common in surgically repaired congenital heart disease (CHD) and carries the potential for significant hemodynamic compromise. Our objective was to determine the incidence, and risk factors of EAT after CHD surgery. Prospective study of patients that underwent surgery for CHD from February to October 2016 was performed. Demographic, perioperative and electrophysiologic data were collected. Sustained EAT (> 30 s) was documented by telemetry or electrocardiogram and confirmed by a pediatric electrophysiologist. All patients were followed through index hospitalization. During the study period, 17/204 (8%) of patients developed EAT with median time-to-event of 14 days. 15/17 (88%) received anti-arrhythmic therapy for sustained EAT. By univariate analysis, younger age (5 vs. 284 days, P < .001), lower weight (3.2 vs. 7.5 kg, P < .001), single ventricle physiology (P = .05), longer cardiopulmonary bypass time (176 vs. 94 min, P < .001), need for delayed sternal closure (P < .001), and higher STAT category (P < .001) were associated with EAT. Incidence among single ventricle patients was 7/44 (16%), and of those 7/13 (54%) were < 30 days of age. Multivariable Cox regression analysis confirmed age at surgery < 30 days (hazard ratio = 11.7, P = .002) and use of milrinone (hazard ratio = 4.4, P = .007) as independent predictors of EAT. Post-operative EAT is frequent following surgery for CHD especially in neonates. Further study is warranted, specifically in the single ventricle population, given the high potential risk for arrhythmia-induced hemodynamic compromise in this vulnerable population.

R-wave synchronised atrial pacing in pediatric patients with postoperative junctional ectopic tachycardia: the atrioventricular interval investigated by computational analysis and clinical evaluation

Background

R-wave synchronised atrial pacing is an effective temporary pacing therapy in infants with postoperative junctional ectopic tachycardia. In the technique currently used, adverse short or long intervals between atrial pacing and ventricular sensing (AP–VS) may be observed during routine clinical practice.

Objectives

The aim of the study was to analyse outcomes of R-wave synchronised atrial pacing and the relationship between maximum tracking rates and AP–VS intervals.

Methods

Calculated AP–VS intervals were compared with those predicted by experienced pediatric cardiologist.

Results

A maximum tracking rate (MTR) set 10 bpm higher than the heart rate (HR) may result in undesirable short AP–VS intervals (minimum 83 ms). A MTR set 20 bpm above the HR is the hemodynamically better choice (minimum 96 ms). Effects of either setting on the AP–VS interval could not be predicted by experienced observers. In our newly proposed technique the AP–VS interval approaches 95 ms for HR > 210 bpm and 130 ms for HR < 130 bpm. The progression is linear and decreases strictly (− 0.4 ms/bpm) between the two extreme levels.

Conclusions

Adjusting the AP–VS interval in the currently used technique is complex and may imply unfavorable pacemaker settings. A new pacemaker design is advisable to allow direct control of the AP–VS interval.

Selective autonomic stimulation of the AV node fat pad to control rapid post-operative atrial arrhythmias

Junctional ectopic tachycardia (JET) and atrial fibrillation (AF) occur in patients recovering from open-heart surgery (OHS). Pharmacologic treatment is used for the control of post-operative atrial arrhythmias (POAA), but is associated with side effects. There is a need for a reversible, modulated solution to rate control. We propose a non-pharmacologic technique that can modulate AV nodal conduction in a selective fashion. Ten mongrel dogs underwent OHS. Stimulation of the anterior right (AR) and inferior right (IR) fat pad (FP) was done using a 7-pole electrode. The IR was more effective in slowing the ventricular rate (VR) to AF (52 +/- 20 vs. 15 +/- 10%, p = 0.003) and JET (12 +/- 7 vs. 0 +/- 0%, p = 0.02). Selective site stimulation within a FP region could augment the effect of stimulation during AF (57 +/- 20% (maximum effect) vs. 0 +/- 0% (minimum effect), p<0.001). FP stimulation at increasing stimulation voltage (SV) demonstrated a voltage-dependent effect (8 +/- 14% (low V) vs. 63 +/- 17 (high V) %, p<0.001). In summary, AV node fat pad stimulation had a selective effect on the AV node by decreasing AV nodal conduction, with little effect on atrial activity.

Supraventricular Tachycardia in Adult Congenital Heart Disease: Mechanisms, Diagnosis, and Clinical Aspects

Supraventricular arrhythmias represent a major source of morbidity in adults with congenital heart disease (ACHD). Anatomic variants and post-operative changes contribute to a unique electrophysiologic milieu ripe for the development of supraventricular tachycardia. Intra-atrial reentrant tachycardia is the most prevalent mechanism. Atrioventricular reciprocating tachycardia is common in lesions associated with accessory pathways. Abnormal anatomy complicates the management of atrioventricular nodal reentrant tachycardia. Tachycardia mediated by twin atrioventricular nodes is rare. Focal tachycardias are considerations in the ACHD population. Each of these tachycardia mechanisms is reviewed, focusing on the inherent diagnostic and therapeutic challenges.

Arrhythmias in Cardiac Critical Care

OBJECTIVES

Here, we characterize the frequency, mechanisms, clinical impact, and potential treatment options for several arrhythmias commonly encountered in pediatric cardiac critical care.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSIONS

Arrhythmias among children in the cardiac critical care setting are common and clinically important, associated independently with prolonged mechanical ventilation, critical care unit stay, and an increase in mortality. The precise characterization of an arrhythmia may provide clues as to an underlying mechanism as well as serve to guide treatment. Arrhythmia therapy, pharmacologic or otherwise, is directed toward addressing the underlying mechanism, and as such may be applicable to the treatment of more than one specific rhythm disturbance. Decisions concerning therapy must call into consideration an arrhythmia's underlying etiology, mechanism, and associated hemodynamic embarrassment, along with the potential for adverse effects of treatment.

Arrhythmia diagnosis and management throughout life in congenital heart disease

Arrhythmias, covering bradycardia and tachycardia, occur in association with congenital heart disease (CHD) and as a consequence of surgical repair. Symptomatic bradycardia can occur due to sinus node dysfunction or atrioventricular block secondary to either unrepaired CHD or surgical repair in the area of the conduction system. Tachyarrhythmias are common in repaired CHD due to scar formation, chamber distension or increased chamber pressure, all potentially leading to abnormal automaticity and heterogeneous conduction properties as a substrate for re-entry. Atrial arrhythmias occur more frequently, but ventricular tachyarrhythmias may be associated with an increased risk of sudden cardiac death, notably in patients with repaired tetralogy of Fallot or aortic stenosis. Defibrillator implantation provides life-saving electrical therapy for hemodynamically unstable arrhythmias. Ablation procedures with 3D electroanatomic mapping technology offer a viable alternative to pharmacologic or device therapy. Advances in electrophysiology have allowed for successful management of arrhythmias in patients with congenital heart disease.

Efficacy of landiolol for the treatment of junctional ectopic tachycardia resulting from sepsis

Junctional ectopic tachycardia, after surgery for CHD, is a serious arrhythmia that can cause increased morbidity and mortality. We report a case of junctional ectopic tachycardia, preceded by sepsis, in a 4-year-old girl, 31 months after open-heart surgery. She was successfully treated using low-dose landiolol hydrochloride.

Magnesium Lowers the Incidence of Postoperative Junctional Ectopic Tachycardia in Congenital Heart Surgical Patients: Is There a Relationship to Surgical Procedure Complexity?

Magnesium sulfate was given to pediatric cardiac surgical patients during cardiopulmonary bypass period in an attempt to reduce the occurrence of postoperative junctional ectopic tachycardia (PO JET). We reviewed our data to evaluate the effect of magnesium on the occurrence of JET and assess a possible relationship between PO JET and procedure complexity. A total of 1088 congenital heart surgeries (CHS), performed from 2005 to 2010, were reviewed. A total of 750 cases did not receive magnesium, and 338 cases received magnesium (25 mg/kg). All procedures were classified according to Aristotle score from 1 to 4. Overall, there was a statistically significant decrease in PO JET occurrence between the two groups regardless of the Aristotle score, 15.3 % (115/750) in non-magnesium group versus 7.1 % (24/338) in magnesium group, P < 0.001. In the absence of magnesium, the risk of JET increased with increasing Aristotle score, P = 0.01. Following magnesium administration and controlling for body weight, surgical and aortic cross-clamp times in the analyses, reduction in adjusted risk of JET was significantly greater with increasing Aristotle level of complexity (JET in non-magnesium vs. magnesium group, Aristotle level 1: 9.8 vs. 14.3 %, level 4: 11.5 vs. 3.2 %; odds ratio 0.54, 95 % CI 0.31-0.94, P = 0.028). Our data confirmed that intra-operative usage of magnesium reduced the occurrence of PO JET in a larger number and more diverse group of CHS patients than has previously been reported. Further, our data suggest that magnesium's effect on PO JET occurrence seemed more effective in CHS with higher levels of Aristotle complexity.

Association between perioperative dexmedetomidine and arrhythmias after surgery for congenital heart disease

BACKGROUND

Dexmedetomidine is commonly used after congenital heart surgery and may be associated with a decreased incidence of postoperative tachyarrhythmias. Using a large cohort of patients undergoing congenital heart surgery, we examined for an association between dexmedetomidine use in the immediate postoperative period and subsequent arrhythmia development.

METHODS AND RESULTS

A total of 1593 surgical procedures for congenital heart disease were performed. Dexmedetomidine was administered in the immediate postoperative period after 468 (29%) surgical procedures. When compared with 1125 controls, the group receiving dexmedetomidine demonstrated significantly fewer tachyarrhythmias (29% versus 38%; P<0.001), tachyarrhythmias receiving intervention (14% versus 23%; P<0.001), bradyarrhythmias (18% versus 22%; P=0.03), and bradyarrhythmias receiving intervention (12% versus 16%; P=0.04). After propensity score matching with 468 controls, the arrhythmia incidence between groups became similar: tachyarrhythmias (29% versus 31%; P=0.66), tachyarrhythmias receiving intervention (14% versus 17%; P=0.16), bradyarrhythmias (18% versus 15%; P=0.44), and bradyarrhythmias receiving intervention (12% versus 9%; P=0.17). After excluding controls exposed to dexmedetomidine at a later time in the hospitalization, dexmedetomidine was associated with increased odds of bradyarrhythmias receiving intervention (odds ratio, 2.18; 95% confidence interval, 1.02-4.65). Furthermore, there was a dose-dependent increase in the odds of bradyarrhythmias (odds ratio, 1.04; 95% confidence interval, 1.01-1.07) and bradyarrhythmias receiving intervention (odds ratio, 1.05; 95% confidence interval, 1.01-1.08).

CONCLUSIONS

Although dexmedetomidine exposure in the immediate postoperative period is not associated with a clinically meaningful difference in the incidence of tachyarrhythmias after congenital heart surgery, it may be associated with increased odds of bradyarrhythmias.

Anatomical Variations of the Blood Vascular System in Veterinary Medicine: The Internal Iliac Artery of the Dog: Part One

Traditional veterinary anatomical models describe the branches of the caudal gluteal artery as the iliolumbar, cranial gluteal, lateral caudal, satellite of the ischiatic nerve and dorsal perineal arteries. However, some classical veterinary anatomy textbooks often indicate variations the general organization of the arterial tree, without giving any pattern of origin or illustrations of the different branching. The aim of this study was to investigate the presumptive variability of the caudal gluteal artery. Two hundred and thirty-two pelvic halves from 116 adult dogs were examined. Twelve anatomical variations were found, nine occurring in more than 5% of the dogs, and three in <5%. A 'long-type' internal iliac artery, which means short caudal gluteal and internal pudendal arteries, was identified, while a 'perineal trunk' was observed as an interesting arterial variation. If the caudal segment alone is taken into consideration, identical vascular patterns in both hemi-pelvises are found in 17% of the dogs. Significant statistical correlation was found for four different types of anatomic variations and gender, two types of variations and body size, one type of variation for body side and one type of variation for head shape.

A common angiotensin-converting enzyme polymorphism and preoperative angiotensin-converting enzyme inhibition modify risk of tachyarrhythmias after congenital heart surgery

BACKGROUND

The angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism is described in association with numerous phenotypes, including arrhythmias, and may provide predictive value among pediatric patients undergoing congenital heart surgery.

OBJECTIVE

The purpose of this study was to examine the role of a common polymorphism on postoperative tachyarrhythmias in a large cohort of pediatric patients undergoing congenital heart surgery with cardiopulmonary bypass (CPB).

METHODS

Subjects undergoing congenital heart surgery with CPB at our institution were consecutively enrolled from September 2007 to December 2012. In addition to DNA, perioperative clinical data were obtained from subjects.

RESULTS

Postoperative tachyarrhythmias were documented in 45% of 886 enrollees and were associated with prolonged mechanical ventilation (P <.001) and intensive care unit length of stay (P <.001). ACE I/D was in Hardy-Weinberg equilibrium (19% I/I, 49% I/D, 32% D/D). I/D or D/D genotypes were independently associated with a 60% increase in odds of new tachyarrhythmia (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.1-2.3, P = .02). Preoperative ACE inhibitor administration was independently associated with a 47% reduction in odds of postoperative tachyarrhythmia in the entire cohort (OR 0.53, 95% CI 0.32-0.88, P = .01), driven by a 5-fold reduction in tachyarrhythmias among I/I genotype patients (OR 0.19, 95% CI 0.04-0.88, P = .02).

CONCLUSION

The risk of tachyarrhythmias after congenital heart surgery is independently affected by the ACE I/D polymorphism. Preoperative ACE inhibition is associated with a lower risk of postoperative tachyarrhythmias, an antiarrhythmic effect that appears genotype dependent. An understanding of genotype variation may play an important role in the perioperative management of congenital heart surgery.