Introduction
In patients with sick sinus syndrome and normal atrioventricular conduction, physiological pacing can be accomplished with either a single chamber atrial pacemaker (AOO and AAI).
In AOO mode, the atrium is paced at a set rate regardless of atrial activity; this is asynchronous atrial pacing.
In AAI mode, the atrium is sensed and the pacemaker is inhibited if the native atrial rate rises above the pacemaker set rate; this is demand atrial pacing.
In general AAI is preferred to AOO because with AOO, pacing can occur during atrial repolarization, possibly inducing atrial fibrillation.
Main indications for atrial pacing
- Symptomatic bradycardia
- Brady-tachy syndrome
ECG features
- Pacing spike precedes the p wave
- The morphology of the P wave depends upon the location of the atrial lead; it may be normal, diminutive, biphasic, or negative
- The PR interval and configuration of the QRS complex are similar to those seen in sinus rhythm. They are independent of the atrial pacemaker; thus, the duration and configuration are determined by the intrinsic characteristics of the patient's conduction system
Figure 1 Atrial pacing spike followed by P wave with spontaneous conduction to ventricles
ECG 1 Atrial pacing spike with spontaneous conduction to ventricles - each atrial spike followed by a P wave.
ECG 2 Each atrial pacing spike followed by a small P wave
References
1) El Gamal M. Atrial pacing, the forgotten pacing mode. Neth Heart J. 2008;16(Suppl 1):S25-S27.
2) Dalia T, Amr BS. Pacemaker Indications. [Updated 2020 Aug 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507823/
3) https://www.uptodate.com/contents/ecg-tutorial-pacemakers
4) Brignole M, Auricchio A, Baron-Esquivias G, Bordachar P, Boriani G, Breithardt OA, Cleland J, Deharo JC, Delgado V, Elliott PM, Gorenek B, Israel CW, Leclercq C, Linde C, Mont L, Padeletti L, Sutton R, Vardas PE; ESC Committee for Practice Guidelines (CPG), Zamorano JL, Achenbach S, Baumgartner H, Bax JJ, Bueno H, Dean V, Deaton C, Erol C, Fagard R, Ferrari R, Hasdai D, Hoes AW, Kirchhof P, Knuuti J, Kolh P, Lancellotti P, Linhart A, Nihoyannopoulos P, Piepoli MF, Ponikowski P, Sirnes PA, Tamargo JL, Tendera M, Torbicki A, Wijns W, Windecker S; Document Reviewers, Kirchhof P, Blomstrom-Lundqvist C, Badano LP, Aliyev F, Bänsch D, Baumgartner H, Bsata W, Buser P, Charron P, Daubert JC, Dobreanu D, Faerestrand S, Hasdai D, Hoes AW, Le Heuzey JY, Mavrakis H, McDonagh T, Merino JL, Nawar MM, Nielsen JC, Pieske B, Poposka L, Ruschitzka F, Tendera M, Van Gelder IC, Wilson CM. 2013 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy: the Task Force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Developed in collaboration with the European Heart Rhythm Association (EHRA). Eur Heart J. 2013 Aug;34(29):2281-329. doi: 10.1093/eurheartj/eht150. Epub 2013 Jun 24. PMID: 23801822.
5) https://litfl.com/pacemaker-rhythms-normal-patterns/
Introduction
In patients with sick sinus syndrome and normal atrioventricular conduction, physiological pacing can be accomplished with either a single chamber atrial pacemaker (AOO and AAI).
In AOO mode, the atrium is paced at a set rate regardless of atrial activity; this is asynchronous atrial pacing.
In AAI mode, the atrium is sensed and the pacemaker is inhibited if the native atrial rate rises above the pacemaker set rate; this is demand atrial pacing.
In general AAI is preferred to AOO because with AOO, pacing can occur during atrial repolarization, possibly inducing atrial fibrillation.
Main indications for atrial pacing
- Symptomatic bradycardia
- Brady-tachy syndrome
ECG features
- Pacing spike precedes the p wave
- The morphology of the P wave depends upon the location of the atrial lead; it may be normal, diminutive, biphasic, or negative
- The PR interval and configuration of the QRS complex are similar to those seen in sinus rhythm. They are independent of the atrial pacemaker; thus, the duration and configuration are determined by the intrinsic characteristics of the patient's conduction system
Figure 1 Atrial pacing spike followed by P wave with spontaneous conduction to ventricles
ECG 1 Atrial pacing spike with spontaneous conduction to ventricles - each atrial spike followed by a P wave.
ECG 2 Each atrial pacing spike followed by a small P wave
References
1) El Gamal M. Atrial pacing, the forgotten pacing mode. Neth Heart J. 2008;16(Suppl 1):S25-S27.
2) Dalia T, Amr BS. Pacemaker Indications. [Updated 2020 Aug 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507823/
3) https://www.uptodate.com/contents/ecg-tutorial-pacemakers
4) Brignole M, Auricchio A, Baron-Esquivias G, Bordachar P, Boriani G, Breithardt OA, Cleland J, Deharo JC, Delgado V, Elliott PM, Gorenek B, Israel CW, Leclercq C, Linde C, Mont L, Padeletti L, Sutton R, Vardas PE; ESC Committee for Practice Guidelines (CPG), Zamorano JL, Achenbach S, Baumgartner H, Bax JJ, Bueno H, Dean V, Deaton C, Erol C, Fagard R, Ferrari R, Hasdai D, Hoes AW, Kirchhof P, Knuuti J, Kolh P, Lancellotti P, Linhart A, Nihoyannopoulos P, Piepoli MF, Ponikowski P, Sirnes PA, Tamargo JL, Tendera M, Torbicki A, Wijns W, Windecker S; Document Reviewers, Kirchhof P, Blomstrom-Lundqvist C, Badano LP, Aliyev F, Bänsch D, Baumgartner H, Bsata W, Buser P, Charron P, Daubert JC, Dobreanu D, Faerestrand S, Hasdai D, Hoes AW, Le Heuzey JY, Mavrakis H, McDonagh T, Merino JL, Nawar MM, Nielsen JC, Pieske B, Poposka L, Ruschitzka F, Tendera M, Van Gelder IC, Wilson CM. 2013 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy: the Task Force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Developed in collaboration with the European Heart Rhythm Association (EHRA). Eur Heart J. 2013 Aug;34(29):2281-329. doi: 10.1093/eurheartj/eht150. Epub 2013 Jun 24. PMID: 23801822.
5) https://litfl.com/pacemaker-rhythms-normal-patterns/
