Bradyarrhythmias are due to sinus nodal disease ( Box 1.1 ) or atrioventricular conduction block ( Box 1.2 ).
Sinus bradycardia
Sinoatrial exit block
Sinus pauses (>3 s)
Sinus node arrest
Tachycardia-bradycardia syndrome
Chronotropic incompetence *
* Maximum predicted heart rate is calculated as 220 – age (y).
First-degree AV block
Second-degree AV block
Type I AV block (Mobitz I or Wenckebach)
Type II AV block (Mobitz II)
Third-degree (complete) AV block.
Tachyarrhythmias are classified as ventricular or supraventricular . The term supraventricular literally indicates tachycardias (atrial rates > 100 beats per minute [bpm] at rest) arising from the His bundle or above. Traditionally, the term supraventricular tachycardia (SVT) has been used to describe all tachycardias that are not solely infra-Hisian in origin, including atrial fibrillation and tachycardias such as atrioventricular reentry as a result of an accessory connection that involves both the atrium and ventricle ( Box 1.3 ). The term narrow QRS tachycardia indicates tachycardia with a QRS duration ≤ 120 milliseconds (ms). A wide QRS tachycardia refers to one with a QRS duration > 120 ms.
Atrial tachycardias
Sinus tachycardia
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Physiologic sinus tachycardia
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Inappropriate sinus tachycardia
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Sinus nodal reentrant tachycardia
Focal atrial tachycardia
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Microreentry
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Automatic
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Multifocal atrial tachycardia
Macroreentrant atrial tachycardia
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Cavotricuspid isthmus dependent
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Typical atrial flutter, counterclockwise (common) or clockwise (reverse)
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Other cavotricuspid isthmus dependent
- •
- •
Noncavotricuspid isthmus dependent
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Right atrial
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Left atrial
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Atrial fibrillation
Atrioventricular junctional tachycardias
Atrioventricular nodal reentrant tachycardia
- •
Typical
- •
Atypical
Nonreentrant junctional tachycardia
- •
Junctional ectopic tachycardia (focal or automatic junctional tachycardia)
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Other nonreentrant variants
Atrioventricular tachycardias
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Orthodromic
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Concealed or manifest atrioventricular accessory pathway conducting in retrograde direction, with anterograde conduction through the atrioventricular node node/His-Purkinje system
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Nodofascicular or nodoventricular bypass tract conducting in retrograde direction, with anterograde conduction through the atrioventricular node/His-Purkinje system
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Antidromic
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Atrioventricular accessory pathway conducting anterograde with retrograde conduction through the AV node or, rarely, over another pathway
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Atriofascicular, atrioventricular, nodofascicular, or nodoventricular bypass tract conducting in the anterograde direction, with retrograde conduction through the AV node or rarely through another pathway
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Ventricular tachycardias
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Monomorphic ventricular tachycardia
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Scar-related reentry
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Bundle branch reentry
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Idiopathic (automatic, reentrant, interfascicular)
- •
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Accelerated idioventricular rhythm
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Polymorphic ventricular tachycardia
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Pleomorphic ventricular tachycardia
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Bidirectional ventricular tachycardia
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Torsades de pointes
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Ventricular flutter
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Ventricular fibrillation
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