- Narrow complex tachycardia, rate just under 300/min
- No definite P waves
- Normal QRS complexes
- ST segment depression in leads V4–V6
A regular narrow complex tachycardia at 300/min probably represents atrial flutter with 1 : 1 conduction (i.e. each atrial activation causes ventricular activation).
What to do ?
The cardiovascular collapse results from the rapid heart rate, with a loss of diastolic filling. Carotid sinus pressure may temporarily increase the degree of block and establish the diagnosis, but it is unlikely to convert atrial flutter to sinus rhythm. Intravenous adenosine is likely to have the same effect as carotid sinus pressure.
A patient who is haemodynamically compromised by a tachycardia should be treated with immediate DC cardioversion.
- READ MORE: Atrial Flutter: ECG Interpretation [With Examples]
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