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Pacemaker: Difference between revisions
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[[Image:paced2.gif|thumb| Ventricular paced rhythm shows ventricular pacemaker spikes]] | [[Image:paced2.gif|thumb| Ventricular paced rhythm shows ventricular pacemaker spikes]] | ||
[[Image:ddd_paced_12lead.jpg |thumb| DDD paced rhythm]] | [[Image:ddd_paced_12lead.jpg |thumb| DDD paced rhythm]] | ||
[[Image:Pacemaker2.jpg |thumb| | [[Image:Pacemaker2.jpg |thumb| Atrial sensed, ventricular paced rhythm (tracking). Note the LBBB morphology with left axis deviation indicating the pacing lead in the right ventricular apex.]] | ||
[[Image:DVA0838.jpg|thumb|Atrial paced rhythm]] | [[Image:DVA0838.jpg|thumb|Atrial paced rhythm]] | ||
A pacemaker is indicated when the electrical impulse conduction or formation is dangerously disturbed. The paced '''pacemaker rhythm''' can easily be recognized on the ECG as it shows '''pacemaker spikes''': vertical signals that represent the electrical activity of the pacemaker. | A pacemaker is indicated when the electrical impulse conduction or formation is dangerously disturbed. The paced '''pacemaker rhythm''' can easily be recognized on the ECG as it shows '''pacemaker spikes''': vertical signals that represent the electrical activity of the pacemaker. Usually these spikes are more visible in unipolar pacing than in bipolar pacing. | ||
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. Another exception is septal or RVOT placement of the pacinglead which results in a less widened to normal QRS complex. | ||
==Pacemaker Coding== | ==Pacemaker Coding== | ||
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* '''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 | ||
* '''VVI''': the ventricles are paced, when the intrinsic ventricular rhythm falls below the pacemakers threshold | * '''VVI''': the ventricles are paced, when the intrinsic ventricular rhythm falls below the pacemakers threshold | ||
* ''VDD''': the pacemaker senses the atrial en ventriculair events, but can only pace the ventricle. This type of pacemaker is used in patients with a reliable sinus node, but suffering from the results of an AV-block. | |||
* '''DDD''': the pacemaker records both the atrial and ventricular rate and can pace one of each chambers when needed. | * '''DDD''': the pacemaker records both the atrial and ventricular rate and can pace one of each chambers when needed. | ||
* '''DDDR''': as above, but the pacemaker has a sensor that records a demand for higher cardiac output and can adjust the heart rate accordingly. | * '''DDDR''': as above, but the pacemaker has a sensor that records a demand for higher cardiac output and can adjust the heart rate accordingly. | ||
* Biventricular pacemakers ('''CRT-P'''): leads in both ventricles are present to synchronize contraction. This cardiac synchronization therapy can improve symptoms and survival in some heart failure patients. | * Biventricular pacemakers ('''CRT-P'''): leads in both ventricles are present to synchronize contraction. The lead pacing the left ventricle is usually positioned in the sinus coronarius. This cardiac synchronization therapy can improve symptoms and survival in some heart failure patients. Echo-optimizing might be helpful in finding the most effective pacingdelay between left and right ventricle. | ||
* '''[[ICD]]''' (Internal Cardioversion Device): this device can detect and treat [[Ventricular Tachycardia]] and [[Ventricular Fibrillation]]. ICDs are a seperate category and usually not put in the pacemaker category, although they do have a pacing function. 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]]. ICDs are a seperate category and usually not put in the pacemaker category, although they do have a pacing function. 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. | ||
* Biventricular ICDs ('''CRT-D'''): an ICD with biventricular pacing option. | * Biventricular ICDs ('''CRT-D'''): an ICD with biventricular pacing option. | ||