Graphic 71302 Version 7.0 https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 14/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate Electrocardiogram (ECG) showing orthodromic atrioventricular reentrant tachycardia (AVRT) Atrioventricular reentrant tachycardia (AVRT) is a supraventricular tachycardia associated with an accessory pathway connection between the atria and ventricles. The pathway may conduct antegrade only, retrograde only, or both antegrade and retrograde. AVRT is usually initiated by an atrial premature beat (arrow). The most common type of AVRT, termed orthodromic AVRT, uses the AV node and His Purkinje system (which has a relatively short refractory period) for antegrade conduction to the ventricles and the accessory AV pathway (which in these patients has a relatively long antegrade refractory period when compared to the node) for retrograde conduction. During orthodromic AVRT, QRS complexes are narrow. During sinus rhythm, however, wide and bizarre QRS complexes (indicative of the WPW pattern) are caused by conduction over both the accessory and normal pathways, resulting in a fusion beat. Since there is 1:1 retrograde activation of the atrium, a negative P wave may be present following the QRS complex. Graphic 54720 Version 5.0 Sinus rhythm The normal P wave in sinus rhythm is slightly notched since activation of the right atrium precedes that of the left atrium. The P wave is upright in a positive direction in leads I and II. A P wave with a uniform morphology precedes each QRS complex. The rate is between 60 and 100 beats per minute and the cycle length is uniform between sequential P waves and QRS complexes. In addition, the P wave morphology and PR intervals are identical from beat to beat. https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 15/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate Graphic 69872 Version 2.0 https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 16/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate 12-lead electrocardiogram (ECG) showing orthodromic atrioventricular reentrant tachycardia (AVRT) in a patient with an accessory AV pathway The 12-lead ECG from a patient with Wolff-Parkinson-White shows a regular tachycardia. However, in contrast to the QRS pattern during sinus rhythm, the QRS complexes are narrow, without evidence of a delta wave or pre-excitation; this is due to the fact that antegrade ventricular activation occurs via the normal atrioventricular node-His Purkinje pathway, while retrograde atrial activation is via the accessory pathway. Therefore, this is called an orthodromic atrioventricular reentrant tachycardia (OAVRT). Courtesy of Martin Burke, DO. Graphic 68804 Version 5.0 ECG in Wolff-Parkinson-White https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 17/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate The 12-lead ECG shows the typical features of Wolff-Parkinson-White; the PR interval is short (*) and the QRS duration prolonged as a result of a delta wave (arrow), indicating ventricular preexcitation. Courtesy of Martin Burke, DO. Graphic 67181 Version 3.0 https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 18/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate Antidromic atrioventricular reentrant tachycardia (AVRT) in the setting of an accessory AV pathway The rhythm strip shows a sinus (S) beat that has a short PR interval and a wide QRS complex as a result of a delta wave (d). Panel A shows the activation sequence with an atrial premature beat (APB,*). The impulse reaches the atrioventricular node (N) before it has repolarized and hence is blocked in this structure. However, the accessory pathway (AP), which has a short refractory period, is able to conduct the impulse antegradely, resulting in an APB with a widened QRS morphology similar to the sinus beat. As seen in panel B, following myocardial activation, the impulse is conducted retrogradely along the His-Purkinje system and AV node, resulting in retrograde atrial activation, seen on the rhythm strip as an inverted P wave. If this activation sequence repeats itself (panel C), a wide QRS complex antidromic atrioventricular reentrant (or reciprocating) tachycardia (AVRT) is established. Graphic 50433 Version 4.0 https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 19/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate 12-lead electrocardiogram (ECG) showing antidromic atrioventricular reentrant tachycardia (AVRT) in a patient with an accessory AV pathway The 12-lead ECG of a patient with Wolff-Parkinson-White shows a regular tachycardia. The QRS complexes are widened and are identical to the QRS complexes seen in sinus rhythm; the antegrade conduction to the ventricle is via the accessory pathway and retrograde conduction is via the normal His- atrioventricular node pathway. This is, therefore, an antidromic atrioventricular reentrant tachycardia (AVRT). Courtesy of Martin Burke, DO. Graphic 54484 Version 20.0 ECG in Wolff-Parkinson-White https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 20/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate The 12-lead ECG shows the typical features of Wolff-Parkinson-White; the PR interval is short (*) and the QRS duration prolonged as a result of a delta wave (arrow), indicating ventricular preexcitation. Courtesy of Martin Burke, DO. Graphic 67181 Version 3.0 https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 21/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate 12-lead electrocardiogram (ECG) showing antidromic atrioventricular reentrant tachycardia (AVRT) The 12-lead ECG shows a wide complex tachycardia in a patient with Wolff- Parkinson-White syndrome and a left lateral accessory pathway. The QRS complexes are wide and have a morphology that is similar to that during sinus rhythm, confirming that this is an antidromic atrioventricular reentrant tachycardia. Graphic 71410 Version 5.0 https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 22/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate WPW syndrome with a left posterior accessory pathway The 12 lead ECG from a patient with Wolff-Parkinson-White syndrome (WPW) shows a short PR interval and a delta wave which results in a widened QRS complex. The delta wave is positive in leads I, avL, and V1 to V6 and negative in leads II, III, and avF, compatible with a left posterior accessory pathway. Graphic 80663 Version 2.0 https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 23/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate Permanent form of junctional tachycardia 12-lead ECG and lead II rhythm strip obtained from a patient with junctional tachycardia at a rate of 165 beats/min. The QRS complex is narrow and there are negative P waves with a long RP interval due to slow retrograde conduction via an accessory pathway. The tachycardia tends to terminate spontaneously and recur, as seen in the rhythm strip. Termination is due to retrograde block in the accessory pathway with absence of the retrograde P wave (arrow). An atrial premature beat (*) reinitiates the tachycardia. Graphic 67767 Version 4.0 https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 24/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate Algorithm for the evaluation of narrow QRS complex tachycardias in stable pati AVNRT: atrioventricular nodal reentrant tachycardia; AVRT: atrioventricular reentrant tachycardia (due to an a electrocardiogram; SANRT: sinoatrial nodal reentrant tachycardia. Graphic 76920 Version 3.0 https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 25/26 7/6/23, 11:12 AM Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway - UpToDate Contributor Disclosures Luigi Di Biase, MD, PhD, FHRS, FACC Consultant/Advisory Boards: Abbott [Ablation products and cardiac devices, defibrillators, or pacemakers of left atrial appendage closure]; Baylis Medical [Cardiac devices, defibrillators, or pacemakers of left atrial appendage closure]; Biosense Webster [Ablation products]; Biotronik [Cardiac devices, defibrillators, or pacemakers of left atrial appendage closure]; Boston Scientific [Ablation products and cardiac devices, defibrillators, or pacemakers of left atrial appendage closure]; Medtronic [Ablation products and cardiac devices, defibrillators, or pacemakers of left atrial appendage closure]; Stereotaxis [Ablation products]; Zoll Medical [Cardiac devices, defibrillators, or pacemakers of left atrial appendage closure]. All of the relevant financial relationships listed have been mitigated. Edward P Walsh, MD No relevant financial relationship(s) with ineligible companies to disclose. Samuel L vy, MD No relevant financial relationship(s) with ineligible companies to disclose. Bradley P Knight, MD, FACC Grant/Research/Clinical Trial Support: Abbott [Electrophysiology]; Atricure [Electrophysiology]; Biosense Webster [Electrophysiology]; Biotronik [Electrophysiology]; Boston Scientific [Electrophysiology]; BSCI [Electrophysiology]; MDT [Electrophysiology]; Philips [Electrophysiology]. Consultant/Advisory Boards: Abbott [Electrophysiology]; Atricure [Electrophysiology]; Biosense Webster [Electrophysiology]; Biotronik [Electrophysiology]; Boston Scientific [Electrophysiology]; BSCI [Electrophysiology]; CVRx [Heart failure]; MDT [Electrophysiology]; Philips [Electrophysiology]; Sanofi [Arrhythmias]. Speaker's Bureau: Abbott [Electrophysiology]; Biosense Webster [Electrophysiology]; Biotronik [Electrophysiology]; Boston Scientific [Transeptal catheterization]; BSCI [Electrophysiology]; MDT [Electrophysiology]. All of the relevant financial relationships listed have been mitigated. Susan B Yeon, MD, JD, FACC No relevant financial relationship(s) with ineligible companies to disclose. Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence. Conflict of interest policy https://www.uptodate.com/contents/atrioventricular-reentrant-tachycardia-avrt-associated-with-an-accessory-pathway/print 26/26