Atrial & SVT · Watch
Atrial Flutter
● Live · lead II25 mm/s · 10 mm/mV
II
10-second rhythm strip · count the boxes
RateAtrial ~300; ventricular 150 (2:1) or 75 (4:1)
RegularityUsually regular (variable block → irregular)
P wavesSawtooth flutter waves, best in II, III, aVF, V1
PR intervalNot measurable
QRSNarrow
Key features
- Sawtooth baseline with no isoelectric segment
- Any regular narrow tachycardia at exactly ~150 bpm → think flutter 2:1
- Adenosine transiently increases block and unmasks flutter waves (shown here at 4:1)