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Pacemaker: Difference between revisions
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In the first example image, the atria are being paced, but not the ventricles, resulting in a '''atrial paced rhythm'''. Accordingly the ventricular beat is delayed until the atrial signal has passed the AV node. In the second image the ventricles are paced directly, resulting in '''ventricular paced rhythm'''. As ventricular pacing occurs exclusively in the right ventricle the ECG shows a left bundle branch pattern. An exception to this rule is left ventricular pacing in patients with congenital anomalies and patients with an epicardial pacemaker that has been placed during surgery. | In the first example image, the atria are being paced, but not the ventricles, resulting in a '''atrial paced rhythm'''. Accordingly the ventricular beat is delayed until the atrial signal has passed the AV node. In the second image the ventricles are paced directly, resulting in '''ventricular paced rhythm'''. As ventricular pacing occurs exclusively in the right ventricle the ECG shows a left bundle branch pattern. An exception to this rule is left ventricular pacing in patients with congenital anomalies and patients with an epicardial pacemaker that has been placed during surgery. | ||
==Pacemaker Coding== | |||
Pacemakers can be categorized according to the NASPE coding system, that usually consists of 3-5 letters. | Pacemakers can be categorized according to the NASPE coding system, that usually consists of 3-5 letters. | ||
* The first letter represents the chamber where the signal is "sensed": O=none, A=atria, V=ventricle, D=dual (atrial and / or ventricle) | * The first letter represents the chamber where the signal is "sensed": O=none, A=atria, V=ventricle, D=dual (atrial and / or ventricle) | ||
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* The fifth letter indicates whether the pacemaker can pace both the atria and right chamber. This letter is seldomly used. | * The fifth letter indicates whether the pacemaker can pace both the atria and right chamber. This letter is seldomly used. | ||
===Commonly Used Pacemakers | {| class="wikitable" style="margin: 1em auto 1em auto" | ||
|+ '''The revised NASPE/BPEG generic code for antibradycardia pacing'''<cite>Bernstein</cite> | |||
! I || II || III || IV || V | |||
|- | |||
| Chamber(s) paced || Chamber(s) sensed || Response to sensing || Rate modulation || Multisite pacing | |||
|- | |||
| O = None || O = None || O = None || O = None || O = None | |||
|- | |||
| A = Atrium || A = Atrium || T = Triggered || R = Rate modulation || A = Atrium | |||
|- | |||
| V = Ventricle || V = Ventricle || I = Inhibited || || V = Ventricle | |||
|- | |||
| D = Dual (A+V) || D = Dual (A+V) || D = Dual (T+I) || || D = Dual (A+V) | |||
|- | |||
|} | |||
==Commonly Used Pacemakers== | |||
The most often used codes are: | The most often used codes are: | ||
* '''AAI''': the atria are paced, when the intrinsic atrial rhythm falls below the pacemakers threshold | * '''AAI''': the atria are paced, when the intrinsic atrial rhythm falls below the pacemakers threshold | ||
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* '''[[ICD]]''' (Internal Cardioversion Device): this device can detect and treat [[Ventricular Tachycardia]] and [[Ventricular Fibrillation]]. Usually the first treatment is anti-tachy pacing (pacing at a rate +- 10% above the ventricular rate in ventricular tachycardia, which can convert the rhythm to sinus rhythm). If this is not effective an defibrillator shock is delivered, usually with 16-36 Joules of energy. ICDs can save lives in patients who have a high risk of ventricular arrhythmias. All ICDs have optional pacemaker activity to treat bradycardias. New biventricular ICDs have 3 leads: an atrial lead, a left ventricular lead and a right ventricular lead. | * '''[[ICD]]''' (Internal Cardioversion Device): this device can detect and treat [[Ventricular Tachycardia]] and [[Ventricular Fibrillation]]. Usually the first treatment is anti-tachy pacing (pacing at a rate +- 10% above the ventricular rate in ventricular tachycardia, which can convert the rhythm to sinus rhythm). If this is not effective an defibrillator shock is delivered, usually with 16-36 Joules of energy. ICDs can save lives in patients who have a high risk of ventricular arrhythmias. All ICDs have optional pacemaker activity to treat bradycardias. New biventricular ICDs have 3 leads: an atrial lead, a left ventricular lead and a right ventricular lead. | ||
==Pacemaker Indications== | |||
A full list of pacemaker indications can be read in the ESC guidelines on cardiac pacing <cite>Vardas</cite>. A selection of class I indications are: chronic symptomatic third- or second degree (Mobtiz I or II) atrioventricular block. Syncope with sinus node disease. Alternating bundle branch block. Persisting AV block after surgery. | A full list of pacemaker indications can be read in the ESC guidelines on cardiac pacing <cite>Vardas</cite>. A selection of class I indications are: chronic symptomatic third- or second degree (Mobtiz I or II) atrioventricular block. Syncope with sinus node disease. Alternating bundle branch block. Persisting AV block after surgery. | ||
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#Vardas pmid=17726042 | #Vardas pmid=17726042 | ||
#Gregoratos pmid=12379588 | #Gregoratos pmid=12379588 | ||
#Bernstein pmid=11916002 | |||
</biblio> | </biblio> | ||
{{clr}} | {{clr}} | ||