By Ahmed Adlan
4 September 2018
A patient attends the pacing clinic for a routine check. She had an episode of palpitations that coincided with the following trace (Figure 1).
Question 1. What is the name of this trace?
Question 2. What is the diagnosis?
Question 3. What type of pacemaker is this from?
Answer 1. Intracardiac electrogram.
Answer 2. Paroxysmal atrial fibrillation.
Answer 3. Dual chamber pacemaker.
Learning points
This trace is called an intracardiac electrogram (EGM). It is a recording of the electrical activity obtained from electrodes placed within the heart. This is different from the commonly used 12 lead electrocardiogram which records electrical activity from electrodes placed on the patient's skin surface. There are three channels seen on the trace (Figure 2). The top channel is called a marker channel and describes the electrical activity for each beat. Common codes include AS (atrial sensed), AP (atrial paced), VS (ventricular sensed) and VP (ventricular paced). The middle channel shows atrial activity (A) while the bottom channel shows ventricular activity (V).
The atrial electrogram shows disorganised activity. Each spike represents atrial activity. The electrical activity is irregular and has varying amplitude. The atrial rate is approximately 380 bpm. The ventricular electrogram is also irregular although the rate is clearly lower than the atrial rate (there are clearly fewer spikes seen in the ventricular EGM compared to the atrial EGM) . The ventricular beats seen are a mixture of native (or sensed, green) and paced (purple) ventricular beats. The paced ventricular beats are preceded by a small pacing spike. The diagnosis is paroxysmal atrial fibrillation.
Given there are both atrial and ventricular electrograms present in this trace we can conclude that this is a dual chamber pacemaker. The electrodes are within the right atrium and right ventricle.
Device deteced atrial high rate episodes
This is a case of device detected atrial fibrillation. Technically cardiac devices cannot definitively distinguish atrial fibrilation from other atrial tachycardias, and hence label such episodes as atrial high rate episodes . The device is programmed with a special algorithm to detect and record such arrhythmias. The management of such a patient with 'device detected atrial fibrillation', in particular anticoagulation for stroke prevention remains controversial. I will be discussing this in a later blog. Follow me on twitter so as to not miss it.
4 September 2018
A patient attends the pacing clinic for a routine check. She had an episode of palpitations that coincided with the following trace (Figure 1).
Question 1. What is the name of this trace?
Question 2. What is the diagnosis?
Question 3. What type of pacemaker is this from?
 |
| Figure 1. Trace obtained from pacemaker. |
Answer 1. Intracardiac electrogram.
Answer 2. Paroxysmal atrial fibrillation.
Answer 3. Dual chamber pacemaker.
Learning points
This trace is called an intracardiac electrogram (EGM). It is a recording of the electrical activity obtained from electrodes placed within the heart. This is different from the commonly used 12 lead electrocardiogram which records electrical activity from electrodes placed on the patient's skin surface. There are three channels seen on the trace (Figure 2). The top channel is called a marker channel and describes the electrical activity for each beat. Common codes include AS (atrial sensed), AP (atrial paced), VS (ventricular sensed) and VP (ventricular paced). The middle channel shows atrial activity (A) while the bottom channel shows ventricular activity (V).
 |
| Figure 2. The atrial electrogram shows disorganised activity. Each spike represents atrial activity. The electrical activity is irregular and has varying amplitude. The atrial rate is approximately 380 bpm. The ventricular electrogram is also irregular although the rate is clearly lower than the atrial rate. The ventricular beats seen are a mixture of native (or sensed, green) and paced (purple) ventricular beats. The paced ventricular beats are preceded by a small pacing spike. The diagnosis is paroxysmal atrial fibrillation. |
The atrial electrogram shows disorganised activity. Each spike represents atrial activity. The electrical activity is irregular and has varying amplitude. The atrial rate is approximately 380 bpm. The ventricular electrogram is also irregular although the rate is clearly lower than the atrial rate (there are clearly fewer spikes seen in the ventricular EGM compared to the atrial EGM) . The ventricular beats seen are a mixture of native (or sensed, green) and paced (purple) ventricular beats. The paced ventricular beats are preceded by a small pacing spike. The diagnosis is paroxysmal atrial fibrillation.
Given there are both atrial and ventricular electrograms present in this trace we can conclude that this is a dual chamber pacemaker. The electrodes are within the right atrium and right ventricle.
Device deteced atrial high rate episodes
This is a case of device detected atrial fibrillation. Technically cardiac devices cannot definitively distinguish atrial fibrilation from other atrial tachycardias, and hence label such episodes as atrial high rate episodes . The device is programmed with a special algorithm to detect and record such arrhythmias. The management of such a patient with 'device detected atrial fibrillation', in particular anticoagulation for stroke prevention remains controversial. I will be discussing this in a later blog. Follow me on twitter so as to not miss it.
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