Dexmedetomidine and magnesium sulfate in preventing junctional ectopic tachycardia after pediatric cardiac surgery.

BACKGROUND: Junctional ectopic tachycardia (JET) is a serious tachyarrhythmia following pediatric cardiac surgery. It isn't easy to treat and better to be prevented. This study aimed to examine the prophylactic effects of dexmedetomidine, MgSO4, or their combination in reducing JET following pediatric open cardiac surgery. METHODS: Hundred and twenty children under 5 years, weighing more than 5 kg, who were scheduled for corrective acyanotic cardiac surgeries were randomized into three groups. Group MD (Dexmedetomidine-MgSO4 group): received dexmedetomidine 0.5 µg/kg IV over 20 min after induction, then infusion 0.5 µg/kg/h for 72 h, and 50 mg/kg bolus of MgSO4 with aortic cross-clamp release, then continued administration for 72 h postoperatively at a dose of 30 mg/kg/day. Group D (the dexmedetomidine group) received the same dexmedetomidine as the MD group in addition to normal saline instead of MgSO4. Group C (control group): received normal saline instead of dexmedetomidine and MgSO4. The primary outcome was the detection of JET incidence; the secondary outcomes were hemodynamic parameters, ionized Mg, vasoactive-inotropic score, extubation time, PCCU and hospital stay, and perioperative complications. RESULTS: The incidence of JET was significantly reduced in Group MD and Group D (p = .007) compared to Group C. Ionized Mg was significantly higher in Group MD than in Groups D and C during rewarming and in the ICU (p < .001). Better hemodynamic profile in Group MD compared to Group D and Group C throughout surgery and in the ICU, the predictive indexes were significantly better in Group MD than in Groups D and C (p < .001). Including the extubation time, PCCU, and hospital stay. CONCLUSION: Dexmedetomidine alone or combined with MgSO4 had a therapeutic role in the prevention of JET in children after congenital heart surgery.

A Comparative Effectiveness Systematic Review and Meta-analysis of Drugs for the Prophylaxis of Junctional Ectopic Tachycardia.

BACKGROUND: Junctional Ectopic Tachycardia (JET) is an arrhythmia originating from the AV junction, which may occur following congenital heart surgery, especially when the intervention is near the atrioventricular junction. OBJECTIVE: The aim of this systematic review and meta-analysis is to compare the effectiveness of amiodarone, dexmedetomidine, and magnesium in preventing JET following congenital heart surgery. METHODS: This meta-analysis was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement, where 11 electronic databases were searched from the date of inception to August 2020. The incidence of JET was calculated with the relative risk of 95% Confidence Interval (CI). Quality assessment of the included studies was assessed using the Consolidated Standards of Reporting Trials (CONSORT) 2010 statement. RESULTS: Eleven studies met the predetermined inclusion criteria and were included in this meta-analysis. Amiodarone, dexmedetomidine, and magnesium significantly reduced the incidence of postoperative JET [Amiodarone: risk ratio 0.34; I2= 0%; Z=3.66 (P=0.0002); 95% CI 0.19-0.60. Dexmedetomidine: risk ratio 0.34; I2= 0%; Z=4.77 (P<0.00001); 95% CI 0.21-0.52. Magnesium: risk ratio 0.50; I2= 24%; Z=5.08 (P<0.00001); 95% CI 0.39-0.66]. CONCLUSION: All three drugs have shown promising results in reducing the incidence of JET. Our systematic review found that dexmedetomidine is better in reducing the length of ICU stays as well as mortality. In addition, dexmedetomidine also has the least pronounced side effects among the three. However, it should be noted that this conclusion was derived from studies with small sample sizes. Therefore, dexmedetomidine may be considered as the drug of choice for preventing JET.

Efficacy of dexmedetomidine in prevention of junctional ectopic tachycardia and acute kidney injury after pediatric cardiac surgery: A meta-analysis.

OBJECTIVE: We conducted a meta-analysis to evaluate the effects of prophylactic perioperative dexmedetomidine administration on postoperative junctional ectopic tachycardia (JET) and acute kidney injury (AKI) in pediatric patients having undergone cardiac surgery. DESIGN: This systematic review was registered with PROSPERO (CRD42017083880). Databases including PubMed, Cochrane Central Register of Controlled Trials, and Web of Science were searched for randomized controlled trials (RCTs) and observational cohort studies from its inception to March 2018. Two reviewers independently screened literature, extracted data, and assessed the quality of included studies using the Jadad scale and Newcastle-Ottawa score. Meta-analysis was then conducted by RevMan 5.3 and Stata 12.0 software. P value < .05 was considered significant. RESULTS: A total of nine eligible studies (5 RCTs and 4 observational studies) comprising 1851 patients were selected for the final analysis. The results of meta-analysis showed that dexmedetomidine significantly reduced the incidence of postoperative JET (OR =0.35, 95% CI: 0.22 to 0.53, P < .00001), but there was no significant difference between groups in AKI (OR =0.44, 95% CI: 0.19 to 1.04, P = .06) and all-cause mortality (OR =0.87, 95% CI: 0.35 to 2.14, P = .77). CONCLUSIONS: The administration of perioperative dexmedetomidine effectively prevents JET in pediatric patients undergoing cardiac surgery but has no significant effect on postoperative renal function. However, the quality of evidence for these findings is low; thus, future larger scale randomized studies are needed to verify the real clinical effects of dexmedetomidine prophylaxis in pediatric patients.

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.

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.

Preincision Initiation of Dexmedetomidine Maximally Reduces the Risk of Junctional Ectopic Tachycardia in Children Undergoing Ventricular Septal Defect Repairs.

OBJECTIVE: To evaluate whether initiation of dexmedetomidine (DEX) infusion before surgical incision and cardiopulmonary bypass (CPB) versus initiation after CPB had an impact on the incidence of junctional ectopic tachycardia (JET). DESIGN: Retrospective cohort study. SETTING: Single tertiary-care cardiac center. PARTICIPANTS: Children undergoing cardiopulmonary bypass for repair of congenital heart disease involving ventricular septal defects between January 2010 and February 2013. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: One hundred thirty-four patients undergoing ventricular septal defect closure were included in the final analysis. Of the 99 patients (74%) exposed to DEX, intraoperative initiation was performed in 73 (pre-CPB, n = 39 patients [29%]; intraoperative post-CPB initiation, n = 34 patients [25%]), and postoperative initiation was performed on arrival to the intensive care unit (ICU) in 26 patients (19%). In 71 of the 73 patients, infusions that were initiated intraoperatively were continued in the postoperative period for up to the first 12 hours. Postoperative JET was observed in 22 of the 134 patients (15%). Of the 99 patients exposed to DEX in the perioperative period, JET was observed in 8 patients (11%). Of the 35 patients not exposed to any DEX, JET was observed in 12 patients (34%). Analysis was performed using DEX exposure and timing as predictor variables. Multivariable analysis modeled with DEX exposure as a predictor variable showed that when initiated preincision and continued through the postoperative period, DEX was associated with significant reduction in postoperative JET (odds ratio [OR] 0.09, 95% confidence interval [CI] 0.02-0.37, p = 0.002). Exposure to DEX in the postoperative period alone did not result in suppression of JET (OR 0.5, 95% CI 0.11-2.17, p = 0.366). When modeled by using timing of DEX initiation as the predictive variable, preincision initiation of DEX infusion resulted in significantly greater suppression of JET (OR 0.04, 95% CI 0.002-0.28, p = 0.006) compared with initiation intraoperatively after CPB (OR 0.16, 95% CI 0.03-0.71, p = 0.024) or on arrival to the ICU (OR 0.504, CI 0.105-2.171, p = 0.365). Use of DEX exclusively in the postoperative period did not demonstrate any significant benefit in reducing JET (OR 0.506, 95% CI 0.106-2.17, p = 0.366). CONCLUSIONS: Preincision initiation of DEX and its continued use during the immediate postoperative period are significantly associated with reduced risk of JET after congenital heart surgeries involving repair of ventricular septal defect.

Management of postoperative junctional ectopic tachycardia in pediatric patients: a survey of 30 centers in Germany, Austria, and Switzerland.

Postoperative junctional ectopic tachycardia (JET) is a frequent complication after pediatric cardiac surgery. Current recommendations on how and when to treat JET are inconsistent. We evaluated the management strategies of postoperative JET in German-speaking countries. We sent an online survey to 30 centers of pediatric cardiology that perform surgery for congenital heart defects in Germany (24), Austria (4), and Switzerland (2). The survey asked 18 questions about how and in what treatment sequence postoperative JET was managed. All 30 centers completed the survey (100% return rate). There was general agreement that the management of JET is based on administration of antiarrhythmic drugs, body surface cooling, and temporary pacing. Many centers presented treatment algorithms based on published literature, all centers named amiodarone as the first drug of choice. Significant disagreement was found concerning the timing and sequential order of additional therapeutic measures and particularly about the dosing of amiodarone and the role of R-wave synchronized atrial pacing. CONCLUSION: This survey reveals that from center to center, the treatment of postoperative JET may vary substantially. Future work should focus on those treatment modalities where a high rate of variation is found. Such studies may be of value to achieve commonly adopted treatment recommendations. What is known: • Treatment of postoperative junctional ectopic tachycardia is predominantly based on administration of antiarrhythmic drugs, therapeutic cooling, and temporary pacing. • Amiodarone is the antiarrhythmic drug of choice in this context. What is new: • Dosing and duration of administration of amiodarone differ relevantly from center to center. • The sequential order of drug administration, therapeutic cooling, and pacing is not consistent.

Efficacy of Prophylactic Dexmedetomidine in Preventing Postoperative Junctional Ectopic Tachycardia After Pediatric Cardiac Surgery.

BACKGROUND: Postoperative junctional ectopic tachycardia is one of the most serious arrhythmias that occur after pediatric cardiac surgery, difficult to treat and better to be prevented. Our aim was to assess the efficacy of prophylactic dexmedetomidine in preventing junctional ectopic tachycardia after pediatric cardiac surgery. METHODS AND RESULTS: A prospective controlled study was carried out on 90 children who underwent elective cardiac surgery for congenital heart diseases. Patients were randomized into 2 groups. Group I (dexmedetomidine group): 60 patients received dexmedetomidine; Group II (Placebo group): 30 patients received the same amount of normal saline intravenously. The primary outcome was the incidence of postoperative junctional ectopic tachycardia. Secondary outcomes included bradycardia, hypotension, vasoactive inotropic score, ventilation time, pediatric cardiac care unit stay, length of hospital stay, and perioperative mortality. The incidence of junctional ectopic tachycardia was significantly reduced in the dexmedetomidine group (3.3%) compared with the placebo group (16.7%) with P<0.005. Heart rate while coming off cardiopulmonary bypass was significantly lower in the dexmedetomidine group (130.6±9) than the placebo group (144±7.1) with P<0.001. Mean ventilation time, and mean duration of intensive care unit and hospital stay (days) were significantly shorter in the dexmedetomidine group than the placebo group (P<0.001). However, there was no significant difference between the 2 groups as regards mortality, bradycardia, or hypotension (P>0.005). CONCLUSION: Prophylactic use of dexmedetomidine is associated with significantly decreased incidence of postoperative junctional ectopic tachycardia in children after congenital heart surgery without significant side effects.

The efficacy of pre-emptive dexmedetomidine versus amiodarone in preventing postoperative junctional ectopic tachycardia in pediatric cardiac surgery.

OBJECTIVE: The objective of this study was to assess the effectiveness of pre-emptive dexmedetomidine versus amiodarone in preventing junctional ectopic tachycardia (JET) in pediatric cardiac surgery. DESIGN: This is a prospective, controlled study. SETTING: This study was carried out at a single university hospital. SUBJECTS AND METHODS: Ninety patients of both sexes, American Society of Anesthesiologists Physical Status II and III, age range from 2 to 18 years, and scheduled for elective cardiac surgery for congenital and acquired heart diseases were selected as the study participants. INTERVENTIONS: Patients were randomized into three groups (30 each). Group I received dexmedetomidine 1 mcg/kg diluted in 100 ml of normal saline intravenously (IV) over a period of 20 min, and the infusion was completed 10 min before the induction followed by a 0.5 mcg/kg/h infusion for 72 h postoperative, Group II received amiodarone 5 mg/kg diluted in 100 ml of normal saline IV over a period of 20 min, and the infusion was completed 10 min before the induction followed by a 10-15 mcg/kg/h infusion for 72 h postoperative, and Group III received 100 ml of normal saline IV. Primary outcome was the incidence of postoperative JET. Secondary outcomes included vasoactive-inotropic score, ventilation time (VT), pediatric cardiac care unit stay, hospital length of stay, and perioperative mortality. MEASUREMENTS AND MAIN RESULTS: The incidence of JET was significantly reduced in Group I and Group II (P = 0.004) compared to Group III. Heart rate while coming off from cardiopulmonary bypass (CPB) was significantly low in Group I compared to Group II and Group III (P = 0.000). Mean VT, mean duration of Intensive Care Unit stay, and length of hospital stay (day) were significantly short (P = 0.000) in Group I and Group II compared to Group III (P = 0.000). CONCLUSION: Perioperative use of dexmedetomidine and amiodarone is associated with significantly decreased incidence of JET as compared to placebo without significant side effects.

Ischemia-reperfusion destabilizes rhythmicity in immature atrioventricular pacemakers: A predisposing factor for postoperative arrhythmias in neonate rabbits.

BACKGROUND: Postoperative arrhythmias such as junctional ectopic tachycardia and atrioventricular block are serious postoperative complications for children with congenital heart disease. We hypothesize that ischemia-reperfusion (I/R) related changes exacerbate these postoperative arrhythmias in the neonate heart and administration of postoperative inotropes is contributory. OBJECTIVE: The purpose of this study was to study the effects of I/R and postischemic dopamine application on automaticity and rhythmicity in immature and mature pacemaker cells and whole heart preparations. METHODS: Single pacemaker cells and whole heart models of postoperative arrhythmias were generated in a rabbit model encompassing 3 primary risk factors: age, I/R exposure, and dopamine application. Single cells were studied using current clamp and line scan confocal microscopy, whereas whole hearts were studied using optical mapping. RESULTS: Four responses were observed in neonatal atrioventricular nodal cells (AVNCs): slowing of AVNC automaticity (from 62±10 to 36 ± 12 action potentials per minute, P<.05); induction of arrhythmicity or increased beat-to-beat variability (0.08 ± 0.04 to 3.83 ± 1.79, P<.05); altered automaticity (subthreshold electrical fluctuations); and disruption of calcium transients. In contrast, these responses were not observed in mature AVNCs or neonatal sinoatrial cells. In whole heart experiments, neonatal hearts experienced persistent postischemia arrhythmias of varying severity, whereas mature hearts exhibited no arrhythmias or relatively transient ones. CONCLUSION: Neonatal pacemaker cells and whole hearts demonstrate a susceptibility to I/R insults resulting in alterations in automaticity, which may predispose neonates to postoperative arrhythmias such as junctional ectopic tachycardia and atrioventricular block.

Safety and Efficacy of Prophylactic Amiodarone in Preventing Early Junctional Ectopic Tachycardia (JET) in Children After Cardiac Surgery and Determination of Its Risk Factor.

Postoperative arrhythmia is a common complication after open heart surgery in children. JET is the most common and dangerous arrhythmia. We aimed to assess safety and efficacy of prophylactic amiodarone in preventing JET in children underwent cardiac surgery and to assess risk factors for JET among our patients. In total, 117 children who underwent cardiac surgery for CHD at Tanta University Hospital from October 2011 to April 2015 were divided in two groups; amiodarone group (65 patients) was given prophylactic amiodarone intraoperatively and placebo group (52 patients). Amiodarone is started as loading dose of 5 mg/kg IV in the operating room after induction of anesthesia and continued for 3 days as continuous infusion 10-15 µg/kg/min. Primary outcome and secondary outcomes of amiodarone administration were reported. We studied pre-, intra- and postoperative factors to determine risk factors for occurrence of JET among these children. Prophylactic amiodarone was found to significantly decrease incidence of postoperative JET from 28.9 % in placebo group to 9.2 % in amiodarone group, and symptomatic JET from 11.5 % in placebo group to 3.1 % in amiodarone group, and shorten postoperative intensive care unit and hospital stay without significant side effects. Risk factors for occurrence of JET were younger age, lower body weight, longer cardiopulmonary bypass, aortic cross-clamp time, hypokalemia, hypomagnesemia, acidosis and high dose of inotropes. JET was more associated with surgical repair of right ventricular outlet obstruction as in case of tetralogy of Fallot and pulmonary stenosis. Most of JET 15/21 (71.4 %) occurred in the first day postoperatively, and 6/21 occurred in the second day (28.6 %). Prophylactic amiodarone is safe and effective in preventing early JET in children after open heart surgery.

Effect of dexmeditomidine on postoperative junctional ectopic tachycardia after complete surgical repair of tetralogy of Fallot: A prospective randomized controlled study.

INTRODUCTION: Incidence of junctional ectopic tachycardia (JET) after repair of tetralogy of Fallot (TOF) is 5.6-14%. Dexmeditomidine is a a-2 adrenoceptor agonist modulates the release of catecholamine, resulting in bradycardia and hypotension. These effects are being explored as a therapeutic option for the prevention of perioperative tachyarrhythmia. We undertook this study to examine possible preventive effects of dexmedetomidine on postoperative JET and its impact on the duration of ventilation time and length of Intensive Care Unit stay. METHODS: After obtaining approval from the hospitals ethics committee and written informed consent from parents, this quasi-randomized trial was initiated. Of 94 patients, 47 patients received dexmedetomidine (dexmedetomidine group) and 47 patients did not receive the drug (control group). RESULTS: Dexmedetomidine group had more number of complex variants like TOF with an absent pulmonary valve or pulmonary atresia (P = 0.041). Hematocrit on cardiopulmonary bypass (CPB), heart rate while coming off from CPB and inotrope score was significantly low in the dexmedetomidine group compared to control group. The incidence of JET was significantly low in dexmedetomidine group (P = 0.040) compared to control group. CONCLUSIONS: Dexmedetomidine may have a potential benefit of preventing perioperative JET.

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.

Landiolol hydrochloride infusion for treatment of junctional ectopic tachycardia in post-operative paediatric patients with congenital heart defect.

AIMS: Junctional ectopic tachycardia (JET) after cardiopulmonary bypass surgery for congenital heart defects is often therapy-resistant and associated with high morbidity and mortality. Improvement of pharmacological therapy is needed. METHODS AND RESULTS: We retrospectively analysed the clinical data of four patients with congenital heart defects, who developed post-operative JET and were treated with landiolol hydrochloride, representing all such patients treated at our university. In two patients, landiolol was used after failure of response to anti-arrhythmic therapies, including thermal control, sedation, discontinuation of catecholamines, and pharmacological therapy with nifekalant and amiodarone. Landiolol was used as a first-line therapy in the other two patients. In all patients, landiolol, at a dose ranging from 1.0 to 10.0 µg/kg/min, achieved successful sinus conversion within 15 min. No adverse events, such as bradycardia, hypotension, or hypoglycaemia, were encountered in all four patients. CONCLUSION: Although limited to a small and heterogeneous group of patients, the results suggest that landiolol is a potentially useful therapeutic option for the well-known difficult condition of post-operative JET, and warrant further investigation in large-scale controlled studies.

Prophylactic amiodarone reduces junctional ectopic tachycardia after tetralogy of Fallot repair.

OBJECTIVE: Junctional ectopic tachycardia is common after pediatric heart surgery. After tetralogy of Fallot repair, the incidence of junctional ectopic tachycardia may be as high as 15% to 20%. We introduced prophylactic amiodarone for tetralogy repair. This study was conducted to evaluate the effectiveness of the prophylactic amiodarone. METHODS: A continuous infusion of amiodarone was started in the operating room at the time of rewarming during cardiopulmonary bypass at a rate of 2 mg/kg/d and continued for 48 hours. Between November 2005 and November 2009, 63 consecutive patients underwent primary repair of tetralogy, of whom 20 had prophylactic amiodarone (amiodarone group) and 43 did not (control group). Variables studied included demographic and bypass data, surgical procedure details (transannular or nontransannular patch), preoperative and postoperative echocardiography findings, and postoperative inotropic support. Univariate and stepwise multivariate analyses were conducted to determine factors associated with the occurrence of junctional ectopic tachycardia. RESULTS: The incidence of junctional ectopic tachycardia was 37% in the control group and 10% in the amiodarone group. The groups were similar in age, weight, bypass time, rate of transannular patch usage, and preoperative and postoperative gradient through the right ventricular outflow tract. Prophylactic amiodarone was significantly negatively associated with junctional ectopic tachycardia by both univariate (P = .039) and multivariate (P = .027) analyses. There were no adverse events attributable to prophylactic amiodarone use. CONCLUSIONS: Prophylactic amiodarone is well tolerated and significantly associated with a decreased incidence of junctional ectopic tachycardia after tetralogy repair.

Magnesium supplementation during cardiopulmonary bypass to prevent junctional ectopic tachycardia after pediatric cardiac surgery: a randomized controlled study.

OBJECTIVES: We analyzed the role of magnesium sulfate (MgSO(4)) supplementation during cardiopulmonary bypass in pediatric patients undergoing cardiac surgery, assessing the incidence of hypomagnesemia and the incidence of junctional ectopic tachycardia. METHODS: We performed a randomized, double-blind, controlled trial in 99 children. MgSO(4) or placebo was administered during the rewarming phase of cardiopulmonary bypass: group 1, placebo group (29 patients); group 2, 25 mg/kg of MgSO(4) (30 patients); and group 3, 50 mg/kg of MgSO(4) (40 patients). RESULTS: At the time of admission to the cardiac intensive care unit, groups receiving MgSO(4) had significantly greater levels of ionized magnesium (group 1, 0.51 + or - 0.07; group 2, 0.57 + or - 0.09; group 3, 0.59 + or - 0.09). Hypomagnesemia before bypass was common (75%-86.2%) and not significantly different among the groups. The proportion of hypomagnesemia decreased significantly at admission to the cardiac intensive care unit in groups receiving MgSO(4) (group 1, 77.8%; group 2, 63%; group 3, 47.4%). Patients receiving placebo (group 1) had a significantly greater occurrence of junctional ectopic tachycardia than groups receiving MgSO(4) (group 1, n = 5 [17.9%]; group 2, n = 2 [6.7%]; group 3, n = 0 [0%]). Age (<1 month), Aristotle score (>4), and history of cardiac failure were associated with junctional ectopic tachycardia. None of the patients with those characteristics in group 3 had junctional ectopic tachycardia. No association was found between study groups and the Pediatric Risk of Mortality score or length of stay in the cardiac intensive care unit. CONCLUSIONS: Supplementation with MgSO(4) during cardiopulmonary bypass seems to reduce the incidence of hypomagnesemia and junctional ectopic tachycardia at admission to the cardiac intensive care unit. This effect seems to be dose related.

Propranolol: a new indication for an old drug in preventing postoperative junctional ectopic tachycardia after surgical repair of tetralogy of Fallot.

Junctional ectopic tachycardia (JET) is a major cause of postoperative morbidity after complete repair of tetralogy of Fallot (TOF). Propranolol is a known medication used in patients with TOF to prevent and control hypercyanotic spells. Despite this, there is little information regarding the relation between preoperative use of propranolol and the incidence of postoperative JET. The aim of this study was to examine the effect of preoperative use of propranolol on the incidence of postoperative JET after full surgical repair of TOF. A retrospective analysis of 109 patients in whom 57 patients received preoperative propranolol (propranolol group) was compared with 52 patients who did not receive propranolol preoperatively (control group). The incidence of postoperative JET was significantly higher in the control group (38%) than the propranolol group (21%) P=0.042. The propranolol group had significantly less mechanical ventilation time, less ICU stay and less total hospital stay than the control group (P<0.05). Our findings suggest that the preoperative use of propranolol may decrease the incidence of JET after full surgical repair of TOF. A prospective randomized study may help to elucidate the exact relationship between the preoperative use of propranolol and the incidence of postoperative JET.

Can successful radiofrequency ablation of atrioventricular nodal reentrant tachycardia be predicted by pattern of junctional ectopy?

BACKGROUND: Emergence of junctional rhythm (JR) during radiofrequency (RF) current delivery directed at the periatrioventricular nodal region has been shown to be a marker of success in atrioventricular nodal reentrant tachycardia (AVNRT). Whereas the characteristics of JR during RF ablation of slow pathway have already been studied, the electrophysiologic features of different patterns of JR are yet to be evaluated. The aim of this study was to investigate in detail the characteristics of the JR that develops during the RF ablation of the slow pathway. MATERIALS AND RESULTS: The study population consisted of 95 patients: 56 women and 33 men (mean age, 47.2 +/- 16.3 years) who underwent slow pathway ablation because of AVNRT. A combined anatomical and electrogram mapping approach was used, and AVNRT was successfully eliminated in all patients. This study identified 7 patterns for JR during the RF ablation of slow pathway: junction-junction-junction, sinus-junction-sinus, intermittent burst, sparse, no junction, sinus-junction-junction, and sinus-junction-block . The characteristics of JR, such as mean cycle length and total number, were gathered. The incidence of JR was significantly higher during effective applications of RF energy than during ineffective applications (P = .001). The mean number of junctional ectopy was 19.6 +/- 19. The total number of junctional ectopy was significantly higher during effective applications of RF energy than during ineffective applications (24.6 +/- 18.8 vs 8.4 +/- 13.2; P < .001). We found a significant difference between the effective and ineffective applications of RF energy in the mean cycle length of the junctional ectopy (464.6 +/- 167.5 vs 263.4 +/- 250.2; P < .01). The patterns of JR were compared between effective and ineffective applications. We managed to show a significant correlation between patterns of JR and successful ablation (P = .01). Logistic regression analysis revealed that the presence of sinus-junction-sinus, sinus-junction-junction, and sinus-junction-block patterns of JR was a predictor of a successful RF ablation (confidence interval [CI], 1.67-15.92 [P < .004]; CI, 1.02-85.62 [P = .048]; and CI, 1.06-32.02 [P = .042], respectively). CONCLUSION: This study confirms that JR is often present during successful slow pathway ablation. The pattern of JR is useful as indicator of success.

[Changes in whole blood ionized magnesium concentration during cardiac surgery employing St. Thomas' cardioplegic solution].

BACKGROUND: Although there is growing evidence to suggest that magnesium supplementation to patients undergoing cardiac surgery is beneficial, the way to administer magnesium is not established. Moreover in Japan St Thomas' cardioplegic solution, containing a high level of magnesium is widely used and the effect of such magnesium-rich cardioplegic solutions on blood magnesium concentration has not been well defined. METHODS: We measured ionized magnesium concentrations (iMg) during cardiac surgery employing St Thomas' solution. Patients were divided into four groups. Group 1 patients were adults and group 2 were children, both of whom received St. Thomas' solution. Group 3 patients underwent cardiopulmonary bypass but did not receive any cardioplegic solution. Group 4 patients underwent off-pump coronary artery bypass grafting. RESULTS: In cardioplegia group (group 1 and 2) iMg was higher than the normal reference range at periods of rewarming, immediately postbypass, and at the end of the operation. iMg at immediately postbypass was related to the total amount of cardioplegic solution. In non-cardioplegia group (group 3 and 4) progressive decrease of iMg was observed throughout the operation. CONCLUSION: Because magnesium in cardioplegic solutions has substantial effect on perioperative iMg, it is crucial to measure iMg to avoid overdose of magnesium when magnesium-rich cardioplegic solutions are employed.

Magnesium supplementation in the prevention of arrhythmias in pediatric patients undergoing surgery for congenital heart defects.

BACKGROUND: The efficacy of magnesium in the prevention of arrhythmias in pediatric patients after heart surgery remains unknown. Therefore we prospectively examined the effect of magnesium treatment on the incidence of postoperative arrhythmias in pediatric patients undergoing surgical repair of congenital heart defects. METHODS AND RESULTS: Twenty-eight pediatric patients undergoing heart surgery with cardiopulmonary bypass were prospectively, randomly assigned in a double-blind fashion to receive intravenous magnesium (magnesium group, n = 13; 30 mg/kg) or saline (placebo group, n = 15) immediately after cessation of cardiopulmonary bypass. Magnesium, potassium, and calcium levels were measured at defined intervals during surgery and 24 hours after surgery. Continuous electrocardiographic documentation by Holter monitor was performed for 24 hours after surgery. Magnesium levels were significantly decreased below the normal reference range for patients in the placebo group compared with the magnesium group on arrival in the intensive care unit and for 20 hours after surgery. Magnesium levels remained in the normal range for patients in the magnesium group after magnesium supplementation. In 4 patients in the placebo group (27%), junctional ectopic tachycardia developed within the initial 20 hours in the intensive care unit. No junctional ectopic tachycardia was observed in the magnesium group (P =.026). CONCLUSIONS: Although this study was originally targeted to include 100 patients, the protocol was terminated because of the unacceptable incidence of hemodynamically significant junctional ectopic tachycardia that was present in the placebo group. Thus low magnesium levels in pediatric patients undergoing heart surgery are associated with an increased incidence of junctional ectopic tachycardia in the immediate postoperative period.