ECG library
Atrial flutter with variable block
advancedAn 'irregular rhythm, query AF' referral; the baseline between the QRS complexes repays a second look.
25 mm/s · 10 mm/mV · synthetic tracing
100%
Calipers:2000 ms50.0 small boxes30 bpm if R-RDrag the orange markers. One small box = 40 ms.
Key findings
- Sawtooth baseline at ~300/min
- Irregular ventricular response whose RR intervals are multiples of one atrial cycle
- No true isoelectric baseline in the inferior leads
Learning points
- Variable-block flutter is the classic AF impostor: the giveaway is RR intervals that cluster at multiples of one flutter cycle rather than varying continuously.
- Rates near exactly 150 or an 'irregularity with a pattern' should always raise flutter; slowing AV conduction unmasks the sawtooth.
- Anticoagulation logic is the same as AF: the atria are still not contracting.
Connected