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CHAPTER SUMMARY AND CENTRAL ILLUSTRATION
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Chapter Summary
This chapter discusses the mechanisms and treatment of supraventricular tachycardia (SVT), a term that encompasses three distinct arrhythmias: atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reciprocating tachycardia (AVRT), and atrial tachycardia (AT). These arrhythmias, while not life threatening, can cause significant symptoms in afflicted patients including palpitations, dizziness, and syncope. AVNRT accounts for roughly two-thirds and AVRT for nearly one-third of SVT cases. AVNRT and AVRT are reentrant rhythms, while AT can be due to triggering or automaticity (see Fuster and Hurst’s Central Illustration). The reentrant circuit for AVNRT includes pathways with distinct electrophysiological properties within the atrioventricular node, while the circuit for AVRT includes the atrioventricular node and an extranodal accessory pathway. Frequently, SVTs can be terminated acutely with vagal maneuvers. Long-term management options include chronic suppression with antiarrhythmic medications or definitive therapy with catheter ablation.
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Supraventricular tachycardias (SVTs) include all tachyarrhythmias that either originate from supraventricular tissue or that incorporate supraventricular tissue in a reentrant circuit. The ventricular rate may be the same or less than the atrial rate, depending on atrioventricular (AV) nodal conduction. The term paroxysmal supraventricular tachycardia (PSVT) refers to a clinical syndrome characterized by a rapid, regular tachycardia with an abrupt onset and termination. Approximately two-thirds of cases of PSVT result from AV nodal reentrant tachycardia (AVNRT). Orthodromic AV reentrant tachycardia (AVRT), which involves an accessory pathway (AP), is the second most common cause of PSVT, accounting for approximately one-third of cases. The term Wolff-Parkinson-White (WPW) syndrome designates a condition comprising both preexcitation and tachyarrhythmias. Atrial tachycardias, which arise exclusively from atrial tissue, account for approximately 5% of all cases of PSVT.1 The purpose of this chapter is to review the mechanism, clinical features, and approach to diagnosis and treatment of patients with AVNRT and AP-mediated tachycardias (including WPW syndrome). Particular attention is focused on reviewing management guidelines developed by the American Heart Association (AHA), American College of Cardiology (ACC), European Society of Cardiology (ESC), and Heart Rhythm Society (HRS; formerly known as the North American Society of Pacing and Electrophysiology).1,2 We will also provide a brief overview of atrial tachycardia.
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ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA
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AVNRT is an important arrhythmia for several reasons. First, AVNRT is extremely common. The incidence of SVT is approximately 35 cases per 100,000 person-years, and the prevalence is 2.25 per 1000; AVNRT accounts for roughly two-thirds of these cases.3 Although AVNRT can occur at any age, it is extremely uncommon before 5 years of age. The usual age of onset is beyond the fourth decade of life and is later than the usual age of onset of AP-mediated tachycardias. Women are affected twice as often as ...