Author: Anna Hartzog MD– Children’s National Hospital, Chinwe Unegbu MD – Children’s National Hospital
A 3-month-old male with Tetralogy of Fallot (TOF) with worsening cyanosis presents for surgical repair with infundibular muscle bundle resection and a transannular patch. Preoperatively, the patient has been on propranolol and his baseline heart rate is 120. Prior to separation from bypass, dopamine is started at 10 mcg/kg/min, the rectal temperature is 35.5 degrees Celsius, and the magnesium level is 2.1 mg/dL. Upon separation from cardiopulmonary bypass (CPB), junctional ectopic tachycardia (JET) is noted with hemodynamic instability. What is the MOST LIKELY contributing factor to JET in this patient?
Correct!
Wrong!
Question of the Week 342
Junctional ectopic tachycardia (JET) is the most common tachyarrhythmia in the postoperative period in children undergoing congenital heart surgery. The reported incidence following pediatric cardiac surgery ranges widely from 2-22%, which is due to differences in study design and the diversity of cardiac lesions represented in those studies.
Congenital heart defects that are known to be major contributors to postoperative JET include ventricular septal defect (VSD), Tetralogy of Fallot (TOF), and complete atrioventricular canal (CAVC). The incidence of JET is greater when the surgical intervention is in close proximity to the atrioventricular (AV) node and bundle of His, as is the case with TOF and CAVC repair. TOF repair is widely recognized as the surgical procedure most likely to be associated with the development of postoperative JET. The reported incidence of JET following TOF repair varies from 4 to 37% in the literature. A 2018 study by Paluszek et al. reported the incidence of JET in pediatric patients following TOF repair to be 13.3%.
Early postoperative JET typically occurs within the first forty-eight hours after pediatric cardiac surgery and is defined as a narrow complex tachycardia with a rate of ≥ 170 bpm. JET originates from the atrioventricular (AV) node or AV junction, which includes the bundle of His. There is often AV dissociation resulting in the ventricular rate exceeding the atrial rate but sometimes there is 1:1 retrograde ventriculoatrial conduction. JET typically manifests with a narrow QRS complex; however, if a bundle branch block is present, then the QRS complex may be wide. The exact etiology of JET is unknown; however, many hypothesize that JET may be the result of direct mechanical trauma (ie surgical sutures) or indirect stretch injury with or without edema to the conduction system which then precipitates automaticity of the AV node/bundle of His.
Despite generally being a self-limiting condition, JET can be associated with postoperative hemodynamic instability and morbidity due to hemodynamic deterioration secondary to extreme tachycardia, loss of AV synchrony, and compromised ventricular filling. In particular, the combination of JET and depressed myocardial function may result in a low cardiac output state and cardiogenic shock.
Risk factors for postoperative JET include an increased baseline preoperative heart rate, cyanotic spells, non-use of beta-blockers in the preoperative period, low intraoperative magnesium and calcium levels, prolonged cardiopulmonary bypass (CPB) and/or aortic cross clamp times, hypothermic circulatory arrest, increased complexity of the surgical procedure, and use of high dose inotropes. Postoperative JET is also associated with a younger age at the time of operation and lower body weight. Younger patients presenting for surgical repair have smaller hearts that are more prone to mechanical or stretch related injury of the conduction system. Both postoperative inotropic score and dopamine use have been independently associated with the occurrence of postoperative JET. This suggests that JET may be triggered by the arrhythmogenic properties of dopamine.
Interventions known to reduce the occurrence of JET after pediatric cardiac surgery include minimization of CPB and aortic cross clamp time, correction of electrolyte imbalances especially magnesium and calcium, use of magnesium sulfate on CPB, optimization/titration of inotropic support with the goal of minimizing exogenous catecholamines, correction of intravascular volume, avoidance of hyperthermia, and adequate use of sedatives and analgesics. Some patients with JET require external pacing to restore AV synchrony. Many antiarrhythmics have been used in the management of JET, including but not limited to digoxin, sotalol, procainamide, and amiodarone. No single antiarrhythmic has been found to be superior. Typically, the antiarrhythmic initiated is simply a matter of institutional preference.
In this question stem, the most likely contributing factor to JET is the use of dopamine. The use of propranolol preoperatively suggests heart rate control and should be preventative against JET. Likewise, the magnesium level prior to separation from CPB was within normal limits and would be preventative as well. The rewarming target temperature of 35.5 is appropriately low and preventative to hyperthermia induced JET.
References
1. Al-Sofyani KA, Jamalaldeen RI, Abusaif SM, Elassal AA, Al-Radi OO. The prevalence and outcome of junctional ectopic tachycardia in pediatric cardiac surgery: Journal of the Egyptian Society of Cardio-Thoracic Surgery. 2017; 25(2): 128-132.
2. Paluszek C, Brenner P, Pichlmaier M, et al. Risk Factors and Outcome of Post Fallot Repair Junctional Ectopic Tachycardia (JET): World J Pediatr Congenit Heart Surg. 2019; 10(1): 50-57. doi: 10.1177/2150135118813124. PMID: 30799715.
3. Dodge-Khatami A, Miller OI, Anderson RH, et al. Surgical substrates of postoperative junctional ectopic tachycardia in congenital heart defects. J Thorac Cardiovasc Surg. 2002; 123(4): 624-630.
4. Ismail MF, Arafat AA, Hamouda TE, et al. Junctional ectopic tachycardia following tetralogy of fallot repair in children under 2 years. J Cardiothorac Surg. 2018; 13(1): 60. doi:10.1186/s13019-018-0749-y
5. Manrique AM, Arroyo M, Lin Y, et al. Magnesium supplementation during cardiopulmonary bypass to prevent junctional ectopic tachycardia after pediatric cardiac surgery: a randomized controlled study. J Thorac Cardiovasc Surg. 2010; 139: 162-169.
6. El Amrousy D, Elshehaby W, Elfeky W, Elshmaa N. Safety and efficacy of prophylactic amiodarone in preventing early junctional ectopic tachycardia (JET) in children after cardiac surgery and determination of its risk factor. Pediatr Cardiol. 2016; 37: 734–739.
Congenital heart defects that are known to be major contributors to postoperative JET include ventricular septal defect (VSD), Tetralogy of Fallot (TOF), and complete atrioventricular canal (CAVC). The incidence of JET is greater when the surgical intervention is in close proximity to the atrioventricular (AV) node and bundle of His, as is the case with TOF and CAVC repair. TOF repair is widely recognized as the surgical procedure most likely to be associated with the development of postoperative JET. The reported incidence of JET following TOF repair varies from 4 to 37% in the literature. A 2018 study by Paluszek et al. reported the incidence of JET in pediatric patients following TOF repair to be 13.3%.
Early postoperative JET typically occurs within the first forty-eight hours after pediatric cardiac surgery and is defined as a narrow complex tachycardia with a rate of ≥ 170 bpm. JET originates from the atrioventricular (AV) node or AV junction, which includes the bundle of His. There is often AV dissociation resulting in the ventricular rate exceeding the atrial rate but sometimes there is 1:1 retrograde ventriculoatrial conduction. JET typically manifests with a narrow QRS complex; however, if a bundle branch block is present, then the QRS complex may be wide. The exact etiology of JET is unknown; however, many hypothesize that JET may be the result of direct mechanical trauma (ie surgical sutures) or indirect stretch injury with or without edema to the conduction system which then precipitates automaticity of the AV node/bundle of His.
Despite generally being a self-limiting condition, JET can be associated with postoperative hemodynamic instability and morbidity due to hemodynamic deterioration secondary to extreme tachycardia, loss of AV synchrony, and compromised ventricular filling. In particular, the combination of JET and depressed myocardial function may result in a low cardiac output state and cardiogenic shock.
Risk factors for postoperative JET include an increased baseline preoperative heart rate, cyanotic spells, non-use of beta-blockers in the preoperative period, low intraoperative magnesium and calcium levels, prolonged cardiopulmonary bypass (CPB) and/or aortic cross clamp times, hypothermic circulatory arrest, increased complexity of the surgical procedure, and use of high dose inotropes. Postoperative JET is also associated with a younger age at the time of operation and lower body weight. Younger patients presenting for surgical repair have smaller hearts that are more prone to mechanical or stretch related injury of the conduction system. Both postoperative inotropic score and dopamine use have been independently associated with the occurrence of postoperative JET. This suggests that JET may be triggered by the arrhythmogenic properties of dopamine.
Interventions known to reduce the occurrence of JET after pediatric cardiac surgery include minimization of CPB and aortic cross clamp time, correction of electrolyte imbalances especially magnesium and calcium, use of magnesium sulfate on CPB, optimization/titration of inotropic support with the goal of minimizing exogenous catecholamines, correction of intravascular volume, avoidance of hyperthermia, and adequate use of sedatives and analgesics. Some patients with JET require external pacing to restore AV synchrony. Many antiarrhythmics have been used in the management of JET, including but not limited to digoxin, sotalol, procainamide, and amiodarone. No single antiarrhythmic has been found to be superior. Typically, the antiarrhythmic initiated is simply a matter of institutional preference.
In this question stem, the most likely contributing factor to JET is the use of dopamine. The use of propranolol preoperatively suggests heart rate control and should be preventative against JET. Likewise, the magnesium level prior to separation from CPB was within normal limits and would be preventative as well. The rewarming target temperature of 35.5 is appropriately low and preventative to hyperthermia induced JET.
References
1. Al-Sofyani KA, Jamalaldeen RI, Abusaif SM, Elassal AA, Al-Radi OO. The prevalence and outcome of junctional ectopic tachycardia in pediatric cardiac surgery: Journal of the Egyptian Society of Cardio-Thoracic Surgery. 2017; 25(2): 128-132.
2. Paluszek C, Brenner P, Pichlmaier M, et al. Risk Factors and Outcome of Post Fallot Repair Junctional Ectopic Tachycardia (JET): World J Pediatr Congenit Heart Surg. 2019; 10(1): 50-57. doi: 10.1177/2150135118813124. PMID: 30799715.
3. Dodge-Khatami A, Miller OI, Anderson RH, et al. Surgical substrates of postoperative junctional ectopic tachycardia in congenital heart defects. J Thorac Cardiovasc Surg. 2002; 123(4): 624-630.
4. Ismail MF, Arafat AA, Hamouda TE, et al. Junctional ectopic tachycardia following tetralogy of fallot repair in children under 2 years. J Cardiothorac Surg. 2018; 13(1): 60. doi:10.1186/s13019-018-0749-y
5. Manrique AM, Arroyo M, Lin Y, et al. Magnesium supplementation during cardiopulmonary bypass to prevent junctional ectopic tachycardia after pediatric cardiac surgery: a randomized controlled study. J Thorac Cardiovasc Surg. 2010; 139: 162-169.
6. El Amrousy D, Elshehaby W, Elfeky W, Elshmaa N. Safety and efficacy of prophylactic amiodarone in preventing early junctional ectopic tachycardia (JET) in children after cardiac surgery and determination of its risk factor. Pediatr Cardiol. 2016; 37: 734–739.
