As with atrial flutter, sometimes the atrioventricular (AV) node can conduct all atrial impulses to the ventricles but frequently there is a degree of AV block. Antiarrhythmic drugs may be effective. Troublesome cases require radiofrequency catheter ablation.
Atrial tachycardia can originate from a focus within either the right or left atrium. It can be sustained or paroxysmal. The practical difference between atrial tachycardia and flutter is that in the former the atrial rate is slower, being between 120 and 240 beats/min. As with atrial flutter, sometimes the atrioventricular (AV) node can conduct all atrial impulses to the ventricles, but often there is a degree of AV block.
ECG characteristics
The atrial rate is slower than in atrial flutter and there is no sawtooth appearance to the baseline (Figures 8.1, 8.2). The ventricular complexes will be narrow unless there is pre-existent bundle branch block, or aberrant intraventricular conduction. Again as for atrial flutter, atrial activity is often best seen in lead V1.
Atrial tachycardia with 1:1 AV conduction may occur (Figure 8.3). Carotid sinus massage is often helpful in the diagnosis (Figure 8.4). Adenosine can also be used to elucidate the diagnosis, but it should be noted that sometimes adenosine will terminate atrial tachycardia without causing transient AV block.
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