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Department of Cardiology, Children's Hospital Boston, 300 Longwood Ave, Boston, MA 02115
(Email: frank.cecchin{at}cardio.chboston.org).
Junctional ectopic tachycardia (JET) is a serious postoperative arrhythmia that occurs in children undergoing palliative or corrective operations for congenital heart disease. A commonly used treatment algorithm for JET was first described by Walsh and colleagues [1] that uses a tiered approach in which general measures are used first, such as AV-synchrony and hypothermia, followed by a combined hypothermic and pharmacologic intervention.
Kovacikova and colleagues [2] evaluated a protocol in which pharmacologic methods were used first. This is a descriptive study in which the authors prospectively treated JET systematically after surgical intervention for congenital heart disease in a single-center cardiac unit. During a 9-year period, 40 patients were recruited with a postoperative diagnosis of JET. Electrolytes, fluid, and temperature homeostasis were checked; then, all patients were treated with a standardized algorithm of 2 mg/kg boluses of amiodarone during a 5- to 10-minute period, up to 10 mg/kg, followed by a discretionary infusion. Second-line therapy was hypothermia to 31° to 35°C. Patients were sedated, intubated, and paralyzed for second-line therapy. The primary outcome measure was restoration of sinus rhythm or "slowing of JET to acceptable heart rate that allows hemodynamic improvement or AV sequential pacing with no recurrence of JET after therapy."
In this study, amiodarone was effective in treatment of postsurgical JET in 45% of patients. They describe hypotension in 70% of patients. One patient required cardiopulmonary resuscitation. Multivariate regression analysis identified higher A-VO2 difference as the most significant predictor of amiodarone failure. This makes sense, because patients with low cardiac output will have high circulating catecholamines, the reduction of which will facilitate JET resolution.
The major limitation to this study is the lack of a control group. However, Batra and colleagues [3] studied the reciprocal approach—hypothermia first, followed by amiodarone. This is essentially the control group for the Kovacikova study [2]. They had the exact same response to therapy: 48% responded to hypothermia and then the rest to the addition of amiodarone. The same result was obtained by Walsh and colleagues [1], who used procainamide instead of amiodarone. Hoffman and colleagues [4] used a tiered approach, but only 39% required any intervention beyond fever reduction, sedation, and minimizing catecholamines.
In summary, it seems that JET resolution is not an adequate therapeutic end point, because all tiered approaches have similar efficacy outcomes and spontaneous resolution rates are high. Side effects related to therapy and time to JET resolution are more appropriate outcome variables. A randomized trial comparing hypothermia or pharmacologic intervention vs combined therapy is needed. Until that trial is performed, a tiered algorithm to the treatment of JET is best with either pharmacologic or hypothermic approach first. Those children with high A-VO2 differences would benefit from a combined hypothermic and pharmacologic approach as first-line therapy.
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