Like children, adult patients with active or abandoned epicardial pacing leads are also at risk of developing life-threatening cardiac ischemia due to mechanical compression of the coronary arteries. As this complication is amenable to surgical removal, these patients require periodic evaluation for myocardial ischemia even if they are asymptomatic.

This report describes the occurrence of T wave sensing by the left ventricular (LV) channel of implantable defibrillators with cardiac resynchronization therapy (CRT-D devices) of Biotronik during biventricular pacing. This finding is different from reported cases that involved T-wave wave sensing by the right ventricular channel of CRT devices.

Loss of pacing capture of the right or left ventricle as well as prolongation of the device-defined LV latency can be automatically unmasked in Biotronik CRT-D devices by Home Monitory of the CRT pacing interrupt algorithm. These situations are associated with short intervals from a pacing stimulus to conducted ventricular activation. These intervals are relatively constant with device-defined latency while those from loss of capture are longer and may be more variable. The true LV latency interval should be re-evaluated whenever the device-defined latency is apparent and prolonged.

A fast ventricular tachycardia was apparently induced in a patient with a CRT-D device by the delivery of a pacemaker stimulus whose timing corresponded with the timing of the QRS complex in the far-field electrogram. Appropriate programming of the device might have prevented this complication.

The terminology of second-degree atrioventricular block has evolved over time, thereby creating some confusion and misinterpretations. Strict adherence to standard terminology and the appropriate use of eponyms are important to avoid diagnostic errors.

The duration of the PR intervals in atypical Wenckebach atrioventricular block before and after a non-conducted P wave can exhibit a wide range of values and patterns. Understanding the different or at times puzzling manifestations of Wenckebach atrioventricular block in terms of its PR intervals can avoid diagnostic errors, especially the erroneous more serious diagnosis of Mobitz type II atrioventricular block.

Nonparoxysmal junctional tachycardia with Wenckebach exit block is known to be associated with digitalis toxicity. This report documents the occurrence of this arrhythmia in the absence of digitalis therapy in a patient with structural heart disease.

Mobitz type II second-degree atrioventricular block (AVB) is an electrocardiographic pattern that describes what appears to be an all-or-none conduction without visible changes in the AV conduction time or PR intervals before and after a single non-conducted P wave. An unchanged PR interval after the block is a sine qua non of Mobitz type II block. A 2:1 AVB cannot be classified in terms of type I or type II AVB. The diagnosis of Mobitz type II block AVB requires a stable sinus rate, which is an important criterion because a vagal surge (generally benign) can cause simultaneous sinus slowing and AV nodal block, which can resemble Mobitz type II AVB. Atypical forms of Wenckebach AVB may be misinterpreted as Mobitz type II AVB when a series of PR intervals are constant before the block. Concealed His bundle or ventricular extrasystoles may mimic both Wenckebach and/or type II AVB (pseudo-AVB). Correctly identified Mobitz type II AVB is invariably at the level of the His–Purkinje system and is an indication for a pacemaker.

The year 2024 marks the centenary of Mobitz's description of type II second-degree atrioventricular block. Its definition remains valid to this day with only minor modification for the diagnosis of infranodal conduction block. Mobitz a century ago indicated that his type II atrioventricular block was associated with Stock-Adams attacks and a prolonged duration of the QRS complex before the eventual description of bundle branch block.

A number of publications have claimed that Mobitz type II atrioventricular block (AVB) may occur during sleep. None of the reports defined type II AVB and representative electrocardiograms were either misinterpreted or missing. Relatively benign Wenckebach type I AVB is often misdiagnosed as Mobitz type II which is an indication for a pacemaker. Review of the published reports indicates that Mobitz type II AVB does not occur during sleep when it is absent in the awake state. Conclusion: There is no proof that sleep is associated with Mobitz type II AVB.

Chapman's (electrographic) sign is of a notch on the ascending limb of the R wave in leads I, aVL and V6. It has been used in the diagnosis of myocardial infarction (MI) during left bundle branch block (LBBB) and cardiac pacing. A number of studies have yielded divergent results about its diagnostic usefulness. However, the sign can be helpful in the diagnosis of MI during LBBB or pacing in the absence of other manifestations of MI.

The use of CRT-D devices with left ventricular (LV) sensing has created controversy about programming various parameters especially the left ventricular T wave protection (LVTP) designed to prevent the delivery of a pacing stimulus into the LV vulnerable period. Such devices are available from two manufacturers. This review focuses only on those provided by Biotronik. As the LVTP controls LV sensing, some investigators have advocated turning off the LVTP to prevent episodic desynchronization known a CRT pacing interrupt. However, LVTP off reduces but does not eliminate this type of desynchronization if triggering of an LV stimulus upon right ventricular sensing (RVs) is programmed on. Deactivation of the LVTP incurs loss of diagnostic data provided by CRT pacing interrupt itself. By choice, the occurrence of CRT pacing interrupt can be totally eliminated by appropriate programming of the LV upper rate interval, LVTP and triggering of an LV pacing event upon RVs. Various programmability options are available according to clinical circumstances. As a rule, clinical judgement must weigh the potential diagnostic benefit of preserving the LVTP capable of recording of episodic CRT pacing interrupt against the loss of diagnostic benefit when LVTP is programmed off (with or without triggering of an LV stimulus upon RVs).

Atrial loss of capture in the chronic phase after implantation may be permanent due to various causes, e.g. technical lead problems or increased scar tissue formation around the lead tip. However, it may also be transient after atrial ischemia in the context of occlusion of the right coronary artery. In this case, it may be preferable to wait for recovery, which may take up to 45 days, instead of immediately performing an atrial lead revision.

The widespread use of disparate definitions of atrioventricular block has created important diagnostic problems. Adherence to the correct definitions provides a logical and simple framework for clinical evaluation. This review focuses on the clinical importance of the definitions in the diagnosis of the various types of atrioventricular (AV) block and the associated diagnostic pitfalls.

Journal of Cardiovascular ElectrophysiologyVolume 34, Issue 10 p. 2122-2123 EDITORIALS Controversies about the terminology of “trifascicular” block S. Serge Barold, Corresponding Author S. Serge Barold [email protected] orcid.org/0000-0003-4951-6465 Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Correspondence S. Serge Barold, Department of Medicine, University of Rochester School of Medicine and Dentistry, 601 Elmwood Av, Rochester, NY 14642, USA. Email: [email protected]Search for more papers by this author S. Serge Barold, Corresponding Author S. Serge Barold [email protected] orcid.org/0000-0003-4951-6465 Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA Correspondence S. Serge Barold, Department of Medicine, University of Rochester School of Medicine and Dentistry, 601 Elmwood Av, Rochester, NY 14642, USA. Email: [email protected]Search for more papers by this author First published: 13 September 2023 https://doi.org/10.1111/jce.16059 Disclosures: None. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. REFERENCES 1Narula OS. Longitudinal dissociation in the His bundle. Bundle branch block due to asynchronous conduction within the His bundle in man. Circulation. 1977;Dec 56(6): 996-1006. 2Surawicz B, Childers R, Deal BJ, Gettes LS, American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; American College of Cardiology Foundation; Heart Rhythm Society. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology. JACC. 2009; 53: 976-981. 3Gubitosa JC, Xu P, Ahmed A, Pergament K. Incomplete trifascicular block and mobitz type II atrioventricular block in COVID-19. Cureus. 2020; 12(9):e10461. 4de Pádua F, Pereirinha A, Marques N, Lopes MG, Macfarlane PW. Conduction defects in macfarlane PW. Conduction defects. In: A Macfarlane, Oosterom, O Pahlm, P Kligfield, M Janse, J Camm, eds. Comprehensive Electrocardiology. Springer; 2012. 5Bayés de Luna A, Riera AP, Baranchuk A, et al. Electrocardiographic manifestation of the middle fibers/septal fascicle block: a consensus report. J Electrocardiol. 2012; 45: 454-460. 6Pérez Riera AR, Ferreira C, Ferreira Filho C, et al. Electrovectorcardiographic diagnosis of left septal fascicular block: anatomic and clinical considerations. Annals Noninvas Electrocardiol. 2011; 16: 196-207. 7Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. 2019; 140: e382-e482. 8Glikson M, Nielsen JC, Kronborg MB, et al. ESC Scientific Document Group. 2021 ESC guidelines on cardiac pacing and cardiac resynchronization therapy. Eur Heart J. 2021; 42: 3427-3520. 9Barold SS, Herweg B. Alternating bundle branch block during atrial bigeminy. Cardiol J. 2012; 19: 548-549. 10Saini A, Padala SK, Koneru JN, Ellenbogen KA. Alternating bundle-branch block: what is the mechanism? Circulation. 2018; 137: 1192-1194. 11Wellens HJ. A wide QRS tachycardia followed by alternating bundle branch block. Heart Rhythm. 2019; 16: 323-324. 12Iwakawa H, Terata K, Tashiro H, Abe Y, Watanabe H. WideQRScomplex tachycardia and alternating bundle branch block aberration: what is the mechanism? J Arrhythm. 2022; 38: 478-481. 13Pellizzón OA, Nannini S, Gonzalez MD. Alternating bundle branch block in a supraventricular tachycardia: which is the mechanism? Medicina. 2019; 79: 197-200 (Spanish). Volume34, Issue10SPECIAL SECTION: CAST‐AF 2022October 2023Pages 2122-2123 ReferencesRelatedInformation