ECG Case 83: Atrial Tachycardia

ECG Interpretation

• Narrow complex tachycardia at 140/min
• Inverted P waves, most obvious in leads II, III, VF
• Short PR interval (about 100 ms)
• Normal axis
• Normal QRS complexes, ST segments and T waves

Atrial Tachycardia
Atrial Tachycardia

Clinical Interpretation

The story of attacks of palpitations could indicate episodes of sinus tachycardia due to anxiety, but the heart rate of 140/min suggests that a rhythm other than sinus rhythm is likely.

This ECG clearly shows a supraventricular tachycardia of some sort, with one P wave per QRS complex. It could be sinus tachycardia, and the short PR interval could indicate pre-excitation, but the abnormal P waves in the inferior leads show that this is an atrial tachycardia.

What to do ?

Carotid sinus massage may terminate the attack, but if not it will almost certainly respond to adenosine. Further attacks may be prevented by a beta-blocker, but the patient should be referred for an electrophysiological study in the hope that a re-entry pathway can be identified and ablated.