Surface electrocardiographic recording from leads VI, II, and V5 in a patient with junctional tachycardia. The upper panel shows sinus rhythm. The lower panel shows tachycardia onset with the characteristic finding of dissociation of the QRS and P waves (narrow arrows on P waves). The large arrow signi- fies continuous recording. Reproduced with permission from Blomstr m-Lundqvist et al.11 Figure 21. Ongoing management of junctional tachycardia. Colors correspond to Class of Recommendation in Table 1; drugs listed alphabetically. SHD indicates structural heart disease (including ischemic heart disease). cyanotic heart disease, single or systemic right ventricles, or Ebstein anomaly, is essential to decision making during SVT treatment. In certain conditions, the presence of cyanosis or severe ventricular dysfunction requires consideration of high- risk cardioversion with resuscitation measures at hand; usu- ally, this decision is made at centers with specialized expertise. Management of ACHD patients should be undertaken only in collaboration with a cardiologist who has specialized training or experience in managing such patients. RCTs assessing antiarrhythmic medication efficacy are lacking. Beta-blocking medications offer the advantages of outpatient medication initiation and may provide protection from tachycardia-mediated hypotension or ischemia. Risks of proarrhythmia are increased with the use of sotalol, ibutilide, dofetilide, and particularly flecainide and require in-hospital and is reserved for patients without ventricular dysfunction who do not respond to other therapy. Sinus node dysfunction may contribute to the development of atrial arrhythmias and may become exacerbated with antiarrhythmic medications. 